BR102017004555A2 - ? CYLINDER HOLE PROVIDED WITH VARIABLE COATING? - Google Patents

Description

Descriptive Report of the Invention Patent for: "VARIABLE COATED CYLINDER HOLE".

[001] DECLARATION ON FEDERAL SPONSORSHIP

[002] RESEARCH AND DEVELOPMENT

The invention was conceived with government support under the Cooperation Agreement DE-EE0006901 granted by the Ministry of Energy. The Federal Government has certain rights in the invention.

[004] TECHNICAL FIELD

This disclosure relates to cylinder bores provided with variable coatings, for example, variable porosity.

[006] BACKGROUND OF THE INVENTION

Engine blocks (cylinder blocks) may include one or more cylinder holes housing pistons of an internal combustion engine. The engine blocks may be cast, for example, from cast iron or aluminum. Aluminum is lighter than cast iron, and can be chosen to reduce a vehicle's weight and improve fuel economy. Aluminum engine blocks may include a liner, such as a cast iron jacket. If it is shirtless, the aluminum engine block may include a liner over the bore surface. Cast iron liners generally increase weight and may result in incompatible thermal properties between the aluminum block and cast iron liners. The shirtless blocks may be coated (e.g., a plasma coated hole process) to reduce wear and / or friction.

[008] SUMMARY OF THE INVENTION

In at least one embodiment, an engine block is provided. The motor block may include a body including at least one cylindrical motor bore wall having a longitudinal axis and including a casing extending along the longitudinal axis and having a casing thickness; the coating is provided with a central region and first and second end regions, and a plurality of pores dispersed within the coating thickness, the central region is provided with a different average porosity from one or both end regions.

[010] The central region may have a greater average porosity than one or both end regions. In one embodiment, one of the end regions extends along a portion along at least one engine bore wall that includes an upper neutral position (TDC) or a lower neutral position (BDC) to the along at least one motor bore wall and the central region extends along a portion along at least one motor bore wall between the TDC position and the BDC position along at least one bore wall engine One or both of the end regions may have an average porosity of 0.1% to 3%. The central region may have an average porosity of at least 5%. One or both of the end regions and the central region may each have an average pore size of 10 to 300 µm. In one embodiment, the coating further includes an intermediate porosity region provided with an average porosity between the central region and one or both of the end regions.

[011] In one embodiment, one of the end regions extends along a portion along at least one engine bore wall that includes an upper dead position (TDC) or a lower dead position ( (BDC) along at least one motor bore wall, the central region extends along a portion along at least one motor bore wall between the TDC position and the BDC position over at least one portion. motor bore wall, and the intermediate porosity region extends along a portion along at least one motor bore wall between said end region and the central region. The central region may extend within a portion along at least one motor bore wall that corresponds to a crankshaft angle of 30 to 150 degrees. The central region may extend along a portion along at least one motor bore wall that includes a maximum piston speed region.

[012] In at least one embodiment, an engine block is provided. The engine block may include a body including a bore wall and a liner overlapping the bore wall having a thickness and pores dispersed within the thickness; the liner including a first depth region disposed adjacent an interface of the liner with the bore wall and a second depth region disposed adjacent an exposed surface of the liner, the second depth region having an average porosity greater than that of the first deep region.

[013] The first depth region may have an average porosity of 0.3% to 2% and the second depth region may have an average porosity of at least 5%. In one embodiment, the coating includes a third depth region disposed between the first and second depth regions within the coating thickness, the third depth region provided with an average porosity between that of the first and second depth regions. The first and second depth regions may be located within a longitudinal portion of the bore wall that corresponds to a crankshaft angle of 30 to 150 degrees.

In at least one embodiment, a method is provided, including spraying a donated coating of a first average porosity onto an engine bore wall in a central longitudinal region; and spraying a coating having a second average porosity onto the motor bore wall at one or more end regions. The first average porosity may be greater than the second average porosity and the first and second average porosities are formed during the spraying steps.

[015] The method may also include spraying a coating having a third average porosity over the motor bore wall into a third longitudinal region, the third average porosity being smaller than the first average porosity. The central longitudinal region may include a longitudinal portion of the bore wall that corresponds to a crankshaft angle of 80 to 100 degrees. Said one or more end regions may include an upper neutral position (TDC) or a lower neutral position (BDC) of the engine bore wall. In one embodiment, the first average porosity is at least 5% and the second average porosity is 0.1% to 3%. The first medium porosity coating and the second medium porosity coating may each have an average pore size of from 10 to 300 µm and the average pore sizes may be formed during the spraying steps.

[016] In at least one embodiment, an article is provided. The article may include a body including at least one sliding surface wall provided with a longitudinal axis. A coating may extend along the longitudinal axis and has a coating thickness. The coating may have a central region and an end region, and a plurality of pores dispersed within the coating thickness. The central region may have a different average porosity than the end region.

[017] In at least one embodiment spray coating equipment is provided. The apparatus may include a spray torch having variable coating parameters and a controller configured to vary variable coating parameters to produce a coating having variable porosity over a coating length and / or depth.

[018] BRIEF DESCRIPTION OF DRAWINGS

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

Figure 2 is a perspective view of a cylinder liner according to one embodiment.

[3] Figure 3 is a cross section of a coated motor bore according to one embodiment.

Figure 4 is a cross section of a coated motor bore according to another embodiment.

Figure 5 is an example of a flow diagram for forming a cylinder bore provided with a variable porosity coating according to one embodiment.

Figure 6 is a cross section of a PTWA coating having a relatively intermediate porosity level, according to one embodiment.

Figure 7 is a cross section of a PTWA coating having a relatively high porosity level, according to one embodiment.

[026] DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosed herein. However, it should be understood that the disclosed embodiments are simple examples of the invention, which may be incorporated in a varied and alternative manner. The figures are not exactly to scale. Some features may be maximized or minimized for the purpose of showing details of particular components. Accordingly, specific and functional details disclosed herein should not be construed as limiting, but simply as a representative basis for teaching a person skilled in the art how to variously employ the present invention.

[028] With reference to fig. 1, an engine or cylinder block 10 is shown. Engine block 10 may include one or more cylinder holes 12, which may be configured to house pistons of an internal combustion engine. The engine block body may be formed of any suitable material, such as aluminum, cast iron, magnesium, or their alloys. In at least one embodiment, the engine block 10 is a linerless engine block. In these embodiments, the holes 12 may have a coating thereon. In at least one embodiment, the engine block 10 may include cylinder liners 14, as shown in Figure 2, inserted into or fused into holes 12. Liners 14 may be a hollow cylinder or hollow tube provided with an outer surface 16 , an inner surface 18, and a wall thickness 20.

[029] If the engine block base material is aluminum, then the cast iron jacket or sleeve may be provided in the cylinder holes to provide the cylinder bore with greater strength, hardness, wear resistance or other properties. . For example, a cast iron liner may be molded into the engine block or compressed into the cylinder holes after the engine block has been formed (e.g. by casting). In another example, the aluminum cylinder holes may be shirtless, but may be coated with a coating after the engine block has been formed (for example, by casting). In another embodiment, the base material of the engine block may be aluminum or magnesium, and an aluminum or magnesium jacket may be inserted or molded into the motor holes. The casting of an aluminum jacket on an aluminum engine block is described in US Patent Application No. 14 / 972,144 filed December 17, 2015, the disclosure of which is incorporated herein in its entirety and by reference herein.

[030] Therefore, the borehole surface of the cylinder holes can be formed in various ways and from a variety of materials. For example, the bore surface may be an iron cast surface (for example, a cast iron motor block or a cast iron liner) or an aluminum surface (for example, a bare liner Al block or a cast iron Al shirt). The disclosed variable coating may be applied to any suitable bore surface, therefore, the term bore surface may apply to a surface of a cylinder liner or sleeve that has been disposed within the cylinder bore (e.g. interference or molding).

Referring to Figure 3, a cylinder bore 30 provided with a variable liner 32 is disclosed. Although a cylinder bore is shown and described, the present disclosure may apply to any article comprising a body including at least one sliding surface wall provided with a longitudinal axis. Prior to the application of the coating 32, the bore surface 34 may be wrinkled. The wrinkling of the hole surface 34 can improve the adhesion or bonding strength of the liner 32 to the hole 30. The wrinkling process can be a mechanical wrinkling process, for example using a cutting edge, grit blasting or grinding tool. Water. Other wrinkling processes may include pickling (e.g., chemical or plasma stripping), spark / electric discharge, or the like. In the embodiment shown, the wrinkling process may be in multiple steps. In the first step, the material may be removed from the hole surface 34 such that projections 36 are formed (in dashed lines). In the second step, projections may be altered to form pending projections 38 with cutouts 40. Projections may be altered using any suitable process such as lamination, cutting, milling, compression, grit blasting, or the like.

Coating 32 may be applied to the wrinkled hole surface. In one embodiment, the coating may be a spray coating, such as a thermally spray coating. Non-limiting examples of thermal spray techniques that may be used to form coating 32 may include plasma spraying, detonation spraying, wire arc spraying (e.g., wire transfer plasma arc, or PTWA), flame spraying , high speed oxy-fuel spray (HVOF), hot spray, or cold spray. 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 the transfer wire arc-plasma spray (PTWA) coating.

[033] A coating spraying equipment 32 may be provided. The equipment may be thermal spray equipment including a spray torch. The spray torch may include torch parameters such as atomizing gas pressure, electric current, plasma gas flow rate, wire feed rate, and torch transverse speed. Torch parameters can be variable such that they are adjustable or variable during torch operation. The apparatus may include a controller which may be programmed or configured to control and vary torch parameters during torch operation. As described in more detail below, the controller may be programmed to vary the torch parameters to suit the porosity of the liner 32 in a longitudinal and / or deep direction. The controller may include a system of one or more computers that may be configured to perform specific operations or actions by virtue of having software, firmware, hardware, or a combination of those installed in the system that, in operation, causes or causes the system performs the disclosed actions. One or more computer programs may be configured to perform specific operations or actions by including instructions that, when performed by the controller, cause the equipment to perform the actions.

Coating 32 can be any suitable coating that provides sufficient strength, stiffness, density, wear properties, friction, fatigue strength, and / or thermal conductivity for a motor block cylinder bore. In at least one embodiment, the coating may be an iron or steel coating. Non-limiting examples of suitable steel compositions may include any grades of AISI / SAE steel from 1010 to 4130 steel. The steel may also be stainless steel, such as those from the AISI / SAE 400 series (e.g. 420). However, other steel compositions may also be used. The coating is not limited to irons or steels, and may also be formed from or include other metals or nonmetals. For example, the coating may be a ceramic coating, a polymeric coating, or an amorphous carbon coating (e.g. DLC or the like). The type and composition of the coating may thus vary based on the desired application and properties. In addition, there may be multiple types of casing in cylinder bore 30. For example, different types of casing (e.g. compositions) may be applied to different regions of the cylinder bore (described in more detail below) and / or the type of casing. coating may change depending on the depth of the entire coating (eg layer by layer).

[035] During the stroke of the piston within the cylinder bore, the friction condition may change based on crank angle or piston location and / or speed. For example, when the piston is in the other near top dead center (TDC) 42 and / or bottom dead center (BDC) 44, the piston speed may be small or zero at the highest and lowest part of the stroke (eg (near the 0 and 180 degree crank angles). When the piston is at or near TDC 42 or BDC 44, the friction condition may be contour friction, where there is roughness contact between the piston and the bore surface (or coating surface when coated). When the piston is moving at relatively high speeds in a central section of the bore length / height (eg crank angle between approximately 35 to 145 degrees), the friction condition may be hydrodynamic friction, where there is little or no no rough contact. When the piston is between these two regions (for example, crank angle between about 10 to 35 or about 145 to 170), either moving to or against TDC 42 or BDC 44, the piston speed is relatively moderate and the Friction condition can be a mix of contour or hydrodynamic friction (eg, some roughness contact). Of course, the crank angles disclosed here are examples, and the transition to different friction conditions (eg, contour to blend) will depend on engine speed, engine architecture, and other factors.

Therefore, the lubrication properties or requirements may differ in different regions of the cylinder bore 30. In at least one embodiment, the porosity of the liner 32 may vary along the height of the bore 30. As used herein, the porosity may refer to pores that are formed during deposition of coating 32 or to pores that are formed in coating 32 after deposition (e.g., by mechanical or chemical texturing). The pores in the liner 32 can act as oil / lubricant holding reservoirs, thereby providing lubrication under severe operating conditions or improving the thickness of the lubricating film. Accordingly, regions having different porosity levels may have different effects on the lubrication of cylinder bore 30. In at least one embodiment, there may be at least two different porosity levels along the height of bore 30. There may be a relatively low porosity region 46 and a relatively high porosity region 48. In the embodiment shown in Figure 3, there may be two low porosity regions 46 and a high porosity region 48 therebetween (e.g., separating regions 46).

A low porosity region 46 may extend over a height of cylinder bore 30 including TDC 42. Region 46 may extend below TDC 42 to a certain extent. For example, region 46 may comprise a certain height of the cylinder bore according to the crank angle of the piston. In one embodiment, region 46 may extend from TDC 42 to a height corresponding to a crank angle of up to 35 degrees. In another embodiment, region 46 may extend from TDC 42 to a height corresponding to a crank angle of up to 30, 25, 20, 15, or 10 degrees. For example, the region may extend from 0 to 35, 0 to 30, 0 to 25, 0 to 20, 0 to 15, 0 to 10, or 0 to 5 degrees.

Another region of low porosity 46 may extend over a height of cylinder bore 30 including BDC 44. Region 46 may extend over BDC 44 to a certain extent. For example, region 46 may comprise a certain height of the cylinder bore according to the crank angle of the piston. In one embodiment, region 46 may extend from BDC 44 to a height corresponding to a crank angle of at most 145 degrees. In another embodiment, region 46 may extend from BDC 44 to a height corresponding to a crank angle of at most 150, 155, 160, 165, or 170 degrees. For example, the region may extend from 145 to 180, 150 to 180, 155 to 180, 160 to 180, 165 to 180, 170 to 180, or 175 to 180 degrees.

The high porosity region 48 may be disposed between the low porosity regions 46. In one embodiment, the high porosity region 48 may extend across the whole height between the low porosity regions 46 as shown in the figure. 3. Similar to the low porosity regions 46, the high porosity region 48 may comprise a certain height of the cylinder bore according to the piston crank angle. The range of crank angles may be any range between those disclosed above for the upper and lower bay porosity regions 46. For example, the high porosity region may extend from the crank angle from 10 to 170 degrees, 15 to 165 degrees, 20 to 160 degrees, 25 to 155 degrees, 30 to 150 degrees, or 35 to 145 degrees, or it may extend at least a portion within any of the above ranges. The lower and lower porosity regions 46 may or may not have the same height. Therefore, the crank angle ranges may be asymmetrical and may extend to any value set forth above for the upper region 46 to any region for the lower region 46. For example, the high porosity region 48 may extend from a crank angle of 15 to 160 degrees.

Similar to the crank angle, the low porosity region (s) 46 and the high porosity region 48 may encompass areas (e.g., height ranges) of the bore surface corresponding to where the piston has a certain velocity. . Low porosity region (s) 46 may correspond to relatively low (or not) areas or velocity, while high porosity region 48 may correspond to relatively high (or maximum) velocity areas. Piston speed may change depending on engine design or configuration. Therefore, areas of the high or low porosity regions can be described in terms of a percentage of the maximum piston speed (max.).

[041] In one embodiment, the low porosity region (s) 46 may encompass a hole area of the cylinder bore surface that corresponds to a piston speed of up to 30% of the maximum speed (including zero speed), for example. , up to 25%, 20%, 15%, 10 %%, or 5% of top speed. As described above, the lower speeds may occur at or near TDC 42 and / or BDC 44. The high porosity region 48 may encompass the equilibrium of the cylinder bore area. For example, the high porosity region 48 may encompass a cylinder bore surface area that corresponds to a piston speed of at least 5%, 10%, 15%, 20%, 25%, or 30% of the maximum speed. . In another embodiment, the high porosity region 48 may encompass an area of the cylinder bore surface that corresponds to a piston speed of 50% to 100% of the maximum speed, or any sub-range between them, such as 60% to 100%. , 70% to 100%, 80% to 100%, 90% to 100%, or 95% to 100 of full speed.

[042] In one embodiment, the porosity (e.g., average porosity) of low porosity regions 46 may be up to 3%. For example, the low porosity region 46 may have a porosity of up to 2.5%, 2% or 1.5%. In one embodiment, the low porosity regions 46 may have a porosity of 0.1% to 3%, or any sub-range between them, such as 0.5% to 3%, 0.5% to 2.5%, 0 , 5% to 2%, 1% to 2.5%, or 1% to 2%. As described herein, "porosity" may refer to a surface porosity, or a percentage of the coating surface that is made up of pores (e.g., void or air, prior to the introduction of lubricant).

The porosity of the high porosity region 48 may be greater than the porosity of the low porosity region (s) 46. In one embodiment, the high porosity region 48 may have a porosity (e.g., medium porosity) of at least at least 2%, for example at least 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. In another embodiment, the high porosity region 48 may have a porosity of 2% to 15%, or any sub-range thereof, such as 2% to 12%, 2% to 10%, 2% to 8%, 3% to 10%, 3% to 8%, 4% to 10%, 4% to 8%, 5% to 10%, or 5% to 8%.

Pore size or diameter, pore depth, and / or pore distribution in the low and high porosity regions may be the same or may be different. In one embodiment, the medium or medium pore sizes of the low porosity regions 46 and the high porosity region 48 may be the same or similar. In this embodiment, the average pore sizes of the low porosity regions 46 and the high porosity region 48 may be from 0.1 to 500 pm, or any sub-range thereof, such as 0.1 to 250 pm, 0.1 to 200 pm, 1 to 500 pm, 1 to 300 pm, 1 to 200 pm, 10 to 300 pm, 10 to 200 pm, 20 to 200 pm, 10 to 150 pm, or 20 to 150 pm.

In another embodiment, the average pore sizes, pore depth, and / or pore distribution of the low porosity regions 46 and the high porosity region 48 may be different. For example, the average pore size of the high porosity region 48 may be larger than the average pore size of the low porosity regions 46, or vice versa. Average pore sizes may be within the ranges disclosed above, but with one being larger than the other within the range. The porosity of each region may be a function of pore size and number of pores. Therefore, for a given medium pore size, a large number of pores will result in a higher porosity, and vice versa. If the average pore size differs between regions, then the relationship between porosity and number of pores may be more complex. For example, the high porosity region 48 may have the same number of pores as the low porosity region 46, but may have a larger number of pores. Alternatively, the high porosity region 48 may have smaller pores, but may have a larger number of pores as long as the total porosity is even greater than in the low porosity region 46. Of course the high porosity region 48 may have both larger pores as a higher number of pores.

Although coating 32 in cylinder bore 30 has been described with two different porosity regions, there may be more than two porosity regions, such as 3, 4, 5, or more different regions. In some embodiments, instead of distinct regions, there may be a porosity gradient along the height of the cylinder bore 30. For example, instead of distinct regions of low porosity 46 and region of high porosity 48, the porosity of the coating 32 may increase from TDC 42 to a peak at a center hole region height and then decrease to BDC 44. Therefore, there may be a minimum relative porosity at or near TDC 42, a maximum relative porosity near a region height bore (eg at a crank angle around 90 degrees, such as 80 to 100 degrees), and a minimum relative bore at or near BDC 44. The change in porosity may be continuous and may be linear / constant. , increase / decrease or it can be a curve. The change in porosity may also be comprised of a plurality of small porosity steps provided with two or more regions (e.g., 2 to N regions). In addition to or instead of the porosity levels of the regions changing as a gradient or a plurality of steps, pore sizes may also change in a similar manner.

Another example of a cylinder bore 30 provided with the liner 32 is shown in FIG. 4. Similar to the embodiment shown in FIG. 3, the liner shown in FIG. 4 also has a relatively low porosity region 46 and a relatively porosity region. In addition, the coating shown in Figure 4 may also have an intermediate porosity region 50, which may have a porosity level that is between that of the low porosity region and the high porosity region 48. In the example shown In Figure 4, there may be two Low Porosity Regions 46 and a High Porosity Region 48, similar to Figure 3. However, there may be two Intermediate Porosity Regions 50, one located or arranged between the Low and High Porosity Regions at Therefore, from TDC 42 to BDC 44, the order of regions can be as follows: low-intermediate-high-intermediate-low.

In one embodiment, the low porosity region (s) 46 and the high porosity region 48 in Figure 4 may have the same or similar porosity values as described above for Figure 3. However, the regions of low and high porosity in Figure 4 may have different values, for example, the bands may be narrowed to provide a porosity level gap for the intermediate porosity regions 50. In one embodiment, the porosity (e.g. average porosity) of the intermediate porosity regions 50 may be from 2% to 7%, or any sub-range thereof, such as 2% to 6%, 3% to 7%, 3% to 5%, 4% to 7%, or 4% to 6%. Similar to the description in Figure 3, the size or diameter of the pores in the low, intermediate and high regions may be the same or may be different. The average pore sizes may be the same or similar to those described above. In embodiments where the average pore sizes of the low porosity regions 46, the intermediate porosity regions 50, and the high porosity regions 48 are different, the average pore sizes of the intermediate porosity regions 50 may be between the pore size average of the high porosity region 48 and low porosity regions 46. Similar to the above, the porosity of intermediate region (s) 50 may be a function of pore size and / or number. For example, the number of pores may be the same as the low and high porosity regions, but the size may be intermediate. Alternatively, the pore sizes may all be the same, but the intermediate region may have an intermediate number of pores. Of course, there may be other pore size and number combinations that also result in an intermediate total porosity.

In the embodiment shown in Figure 4, the high porosity region 48 may extend over a central or middle portion of the cylinder bore height. For example, the high porosity region 48 may extend over the height of the cylinder bore corresponding to a 90 degree crank angle. In one embodiment, the high porosity region 48 may extend over the height of the cylinder bore corresponding to a crank angle of 60 to 120 degrees, or any sub-range thereof, such as 70 to 110 degrees or 80 to 100 degrees. , or extend over at least a portion of the above bands. The low porosity regions 46 may extend over the same or similar crank angle ranges as described in Figure 3. Therefore, the crank angle ranges of the intermediate porosity regions 50 may be between the ranges for the angle ranges. low and high porosity.

Similar to the above, areas of low, intermediate and high porosity may be described in terms of the cylinder area or height corresponding to a piston speed. Therefore, the low porosity region (s) 46 may comprise an area of the cylinder bore surface that corresponds to a relatively low piston velocity (e.g. including zero), the high porosity region (s) 48 may encompass a cylinder bore surface area that corresponds to a relatively high piston speed (e.g., including maximum speed), and intermediate porosity region (s) 50 may comprise a cylinder bore surface area that corresponds to a piston speed between that of the low and high speed areas (for example, not including zero or maximum).

[051] In one embodiment, the low porosity region (s) 46 may encompass a cylinder bore surface area that corresponds to a piston speed of up to 30% of the maximum speed (including zero speed), for example up to 25%, 20%, 15%, 10 %%, or 5% of top speed. As described above, the lower speeds may occur at or near TDC 42 and / or BDC 44. The intermediate porosity region (s) 50 may encompass a cylinder bore surface area that corresponds to a piston speed of 5 % to 80% of top speed, or any under range in between. For example, intermediate porosity region (s) 50 may cover an area corresponding to 10% to 80%, 15% to 80%, 20% to 80%, 30% to 80%, 40% to 80%, 30% 70%, 30% to 60%, 20% to 50%, or 10% to 50% of full speed, or others. In one embodiment, the high porosity region (s) 48 may encompass a cylinder bore surface area that corresponds to a piston speed of at least 30%, 40%, 50%, 60%, 70%, or 80. % of maximum speed (including maximum). In another embodiment, the high porosity region 48 may encompass a cylinder bore surface area that corresponds to a piston speed of 50% to 100% of the maximum speed, or any sub-range thereof, such as 60% to 100%. , 70% to 100%, 80% to 100%, 90% to 100%, or 95% to 100 of full speed. In one embodiment, the percentage of maximum velocity of intermediate porosity regions 50 may be between and / or form the equilibrium of the bands for the high and low porosity bands.

The coating 32 may be a single layer or may be formed of multiple layers. For example, if coating 32 is applied using a thermal spray method (e.g. PTWA), there may be multiple layers sprayed onto the bore surface to constitute coating 32 to its final thickness. Thermal spray can be applied by a rotating nozzle or by rotating the bore surface around a stationary nozzle. Therefore, with each revolution of the nozzle and / or bore surface a new layer may be deposited on the coating formation 32.

As described above, porosity levels (for example, low, intermediate or high porosity regions) may be surface porosity levels. However, there may also be variation in porosity as a function of coating depth 32.

[053] In one embodiment, coating 32 may have a burnished thickness of 25 to 500 μιτι, for example, 25 to 250 pm, 50 to 500 pm, 50 to 250 pm, 25 to 100 pm, or 25 to 75 pm. It has been found that the porosity of the liner 32 may affect the adhesion or bonding of the liner 32 to the bore surface (e.g., bore or aluminum jacket). In general, the adhesion of the liner 32 to the bore surface may increase with reduced porosity. Therefore, in at least one embodiment, the average porosity of the liner 32 may be smaller at the interface between the liner 32 and the bore surface than at the liner surface 32 (e.g., the exposed surface making contact with the piston).

Similar to surface porosity regions, there may be two or more distinct porosity regions along the thickness of the coating or there may be a gradient or porosity that changes constantly over the thickness. The porosity of coating 32 at the interface with the bore surface may be up to 2%, for example 0.1% to 2%, 0.3% to 2%, 0.5% to 2%, 0.1%. 1.5%, 0.1% to 1%, 0.5% to 2%, or 0.5% to 1.5%. The porosity of the coating 32 on the surface is described above, and may vary depending on the location of the coating along the height of the cylinder bore 30. Therefore, there may be variations in porosity along both the height and depth of the coating 32 along the cylinder bore 30.

The change in porosity along the coating thickness may be comprised of a plurality of small porosity steps provided with two or more regions (e.g., 2 to N regions). In one embodiment, the regions may correspond to the thickness of a single layer of the coating as it is applied. For example, if five layers of PTWA are deposited and each has a thickness of 10 pm, the total coating thickness may be 50 pm. Porosity can be adjusted during each, some, or all layer depositions. For example, the porosity may increase in each subsequent layer such that the porosity continuously increases from the interface to the surface of the coating 32. Alternatively, some layers may be formed with the same porosity, such that there are steps in porosity of the surface. interface to the coating surface.

[056] In addition to variations in porosity and / or pore size in liner 32 as a function of cylinder bore height and / or depth, variations in other properties may also exist. In one embodiment, the microhardness of the coating may vary depending on the height within the cylinder bore. For example, microhardness may vary in a similar manner to porosity such that there are regions or zones within the engine bore with different microhardnesses. Therefore, regions of low, high and / or intermediate porosity may also have different levels of microhardness. Similar to porosity, there may be two, three, four or more different microhardnesses. Microhardnesses may change in stages or may be continuous or substantially continuous (for example, many very small distinct changes). Similar to porosity, microhardness can be altered by adjusting coating deposition process parameters such as torch parameters.

[057] In one embodiment, the microhardness of the coating 32 may be higher in lower porosity regions than in higher porosity regions. For example, in some embodiments, lower porosity regions 46 may also be regions of high microhardness. Regions including and adjacent to TDC 42 and BDC 44 may have higher microhardness than regions where the piston travels at relatively high speed (e.g., crank angle approximately 90 degrees). Microhardness in high microhardness regions can be from 150 to 600 HV, or any sub-range between it. For example, microhardness in the high microhardness regions may be from 200 to 500 HV, 200 to 400 HV, 250 to 500 HV, or 250 to 400 HV. In some embodiments, the microhardness of the entire coating may be within the above ranges, however, the high microhardness regions may have a higher microhardness within the range.

Referring to Figures 3-5, methods of forming the disclosed variable porosity coatings are described. Figure 5 shows a flow chart 100 of a method for forming a cylinder bore liner having variable porosity. As described above, however, the method may apply to forming the coating having variable porosity in any article body, including at least one sliding surface wall provided with a longitudinal axis. In step 102, the bore surface may be prepared to receive the coating. As described above, the bore surface may be a fused motor bore or a sleeve (molded or interference fit). Surface preparation may include wrinkling and / or surface washing to improve adhesion / bonding of the coating.

[059] At step 104, coating deposition can begin. As described above, the coating may be applied in any suitable manner, such as by spraying. In one example, the coating may be applied by thermal spraying, such as PTWA spraying. The coating may be applied by rotary spraying of the coating onto the bore surface. The spray nozzle, bore surface, or both can be rotated for coating application. As disclosed above, the coating portion at the interface with the bore surface may have low porosity to promote bonding / adhesion. Therefore, the initial layer of the lining may be the same over the entire height of the lining cylinder bore. However, in other embodiments, there may be variation in initial coating porosity based on height.

[060] At step 106, deposition parameters can be adjusted (for example, by a controller) to produce varying levels of porosity in the coating. Adjustments can be made while the coating is being applied or the application can be stopped to adjust the parameters. The parameters may be adjusted to form the coating structure (s) described above. For example, the parameter may be adjusted to form regions of low, intermediate and / or high porosity on the coating surface at the disclosed locations. Parameters can also be adjusted to form porosity changes as a function of coating depth as described. The parameters to be adjusted may vary based on the type of deposition and the type of specific equipment used. In the example where PTWA spraying is used, the torch, or other operating parameters may be adjusted to change the porosity. For example, it has been found that parameters such as atomizing gas pressure, electric current, plasma gas flow rate, wire feed rate and torch cross-speed can be adjusted to increase or decrease the porosity of the coating. By adjusting these parameters one can change the size, temperature and velocity of the metal particles and consequently change the microstructure and / or coating composition in favor of higher or lower porosity levels.

[061] In step 108, additional coating layers can be applied using the set deposition parameters. While steps 104, 106, and 108 are shown as separate steps, in practice two or all three can be combined into one step. The parameters can be adjusted during a deposition process such that the layers are formed with varying porosities at different heights / thicknesses. In addition, if there are multiple layers within the entire coating, the layers may have the same or different thicknesses. For example, each layer may have the same thickness, such as 5, 10, 15, or 20 μιη, or there may be two or more different layer thicknesses within the entire coating.

[062] In step 110, the finished liner can be honed to a final bore diameter according to the specified motor bore dimensions. In some embodiments, an optional mechanical machining operation such as boring, cubing, etc. may be performed prior to honing to reduce the amount of material removal during honing. In general, the honing process includes a rotary tool provided with abrasive particles in the cylinder bore to remove material to a controlled diameter. In the embodiments shown in Figures 3 and 4, the liner 32 may initially be deposited to a thickness 52, shown in a dashed line. The honing process can remove material from the liner 32 and provides a highly cylindrical bore wall 54 with the final bore diameter. As described herein, the porosity coating surface may be the surface resulting from the honing process, not the initial surface after deposition (e.g. the bore wall 54, not the initial thickness 52).

[063] After the honing step, post-clearance machining can be performed at step 112. This step may include additional conventional machining processes to finish the cylinder bore. In addition, step 112 may include machining processes for opening or creating additional pores on the surface of liner 32. For example, there may be an additional wash step, such as a high pressure wash (for example, with water or other fluid ), a brushing step, or a dry ice blasting step.

[064] Referring to Figures 6 and 7, the cross sections of two examples of PTWO coatings are shown showing different porosities. Figure 6 shows a PTWO coating having a relatively medium or moderate porosity of 6.73%. Figure 7 shows a PTWO coating having a relatively high porosity of 8.65%.

Therefore, the coatings in figures 6 and 7 could be used as regions of intermediate and high porosity, respectively, as described above. As shown, the pores are dispersed within and throughout the coating, including at the interface with the cylinder wall (e.g., an unfinished jacket or block), the volume of the coating, and / near the surface of the coating.

[065] It has been found that the disclosed cylinder bore with a variable coating can improve cylinder lubrication as well as reduce friction and wear. As described above, when the piston is at or near TDC 42 or BDC 44, the friction condition may be boundary friction, where there is roughness contact between the piston and the bore surface (or coating surface when coated ). This friction condition may not require large amounts of lubrication to fill the small gaps between the piston and the bore / casing surface. Accordingly, the coating may have relatively low porosity in regions where contour friction occurs (e.g. at zero and low piston speeds and corresponding to crank angles).

[066] When the piston is traveling at relatively high speeds in a central section of the hole length / height, the friction condition may be hydrodynamic friction, where there is little or no roughness contact and a larger clearance between the piston. and the surface of the hole / casing. This friction condition may require larger amounts of lubrication to fill larger gaps between the piston and the bore / casing surface. Accordingly, the coating may have relatively high porosity in regions where hydrodynamic friction occurs (e.g., at maximum and near maximum piston speeds and corresponding to crank angles).

[067] When the piston is between these two regions, or moving towards or against TDC 42 or BDC 44, the piston speed is relatively moderate and the friction condition may be a mixture of contour and hydrodynamic friction (eg , some rough contact). This friction condition may require moderate amounts of lubrication to fill the moderate clearances between the piston and the bore / casing surface. Accordingly, the coating may have relatively intermediate porosity in regions where frictional mixing occurs (e.g. at intermediate piston speeds and corresponding to crank angles).

[068] In addition to the friction condition, the piston speed also changes as a function of the piston position in the cylinder bore. At TDC and BDC, the speed is zero or substantially zero and is relatively low at crank angles near TDC / BDC. Speed increases as the piston travels toward the middle / center of the cylinder and can reach a maximum at or near the middle / center (for example, at or about 90 degrees crank angle). Frictional forces may change as a function of velocity, generally increasing as velocity increases. Therefore, it has been found that providing higher porosity levels in the cylinder bore liner in the maximum speed regions can improve lubrication and reduce friction. As described above, the porosity may vary along the hole height to match the friction condition, piston speed, and / or crank angle to provide a certain amount of lubrication in each area. There may be two or more regions of different porosities (e.g. 2, 3, 4, 5, or more) or the porosity may be adjusted continuously or in very small discrete steps.

Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. On the contrary, the words used in the report are words of description, not limitation, and it is understood that various changes can be made without departing from the spirit and scope of the invention. Additionally, the features of various implementation embodiments may be combined to form other embodiments of the invention.

Claims (22)

An engine block comprising: a body including at least one cylindrical motor bore wall having a longitudinal axis and including a covering extending along the longitudinal axis and having a coating thickness; the coating is provided with a central region and first and second end regions, and a plurality of pores dispersed within the coating thickness, the central region is provided with a different average porosity from one or both end regions. Motor block according to Claim 1, characterized in that the central region has an average porosity greater than one or both end regions. Engine block according to Claim 2, characterized in that one of the end regions extends along a portion along at least one engine bore wall including an upper dead center position (TDC). or a lower dead center position (BDC) along at least one engine bore wall and the central region extending along a portion along at least one engine bore wall between the TDC position and the position BDC along at least one motor bore wall. Motor block according to Claim 2, characterized in that one or both of the end regions have an average porosity of 0.1% to 3%. Motor block according to Claim 2, characterized in that the central region has an average porosity of at least 5%. Motor block according to Claim 2, characterized in that one or both of the end regions and the central region each have an average pore size of 10 to 300 µm. Motor block according to Claim 2, characterized in that the coating further includes an intermediate porosity region having a medium porosity between the central region and one or both of the end regions. Engine block according to claim 7, characterized in that one of the end regions extends along a portion along at least one engine bore wall including an upper dead center position (TDC). or a lower dead center position (BDC) along at least one engine bore wall, the central region extending along a portion along at least one engine bore wall between the TDC position and the position BDC along at least one motor bore wall, and the intermediate porosity region extending along a portion along at least one motor bore wall between said one end region and the central region . Motor block according to Claim 2, characterized in that the central region extends within a portion along at least one motor bore wall corresponding to a crankshaft angle of 30 to 150 degrees. . Motor block according to Claim 2, characterized in that the central region extends along a portion along at least one motor bore wall including a maximum piston speed region. An engine block comprising: a body including a bore wall and a liner overlapping the bore wall having a thickness and pores dispersed within the thickness; the coating including a first depth region adjacent an interface of the coating with the bore wall and a second depth region disposed adjacent an exposed surface of the coating, the second depth region having an average porosity greater than that of the first region. deep. Motor block according to Claim 11, characterized in that the first depth region has an average porosity of 0.3% to 2% and the second depth region has an average porosity of at least 5%. Motor block according to Claim 11, characterized in that the coating includes a third depth region disposed between the first and second depth regions within the coating thickness, the third depth region having an average porosity between that of the first and second deep regions. Motor block according to Claim 11, characterized in that the first and second depth regions are located within a longitudinal portion of the bore wall which corresponds to a crankshaft angle of 30 to 150 degrees. A method comprising: spraying a coating having a first average porosity on an engine bore wall in a central longitudinal region; and spraying a coating having a second average porosity onto the motor bore wall at one or more end regions; wherein the first average porosity is greater than the second average porosity and the first and second average porosities are formed during the spraying steps. A method according to claim 15 further comprising spraying a coating having a third average porosity over the motor bore wall into a third longitudinal region, the third average porosity being less than the first average porosity. . A method according to claim 15, characterized in that the central longitudinal region includes a longitudinal portion of the bore wall that corresponds to a crankshaft angle of 80 to 100 degrees. Method according to claim 15, characterized in that said one or more end regions include an upper dead position (TDC) or a lower dead position (BDC) of the engine bore wall. Method according to claim 15, characterized in that the first average porosity is at least 5% and the second average porosity is from 0.1% to 3%. Method according to claim 15, characterized in that the coating having the first medium porosity and the coating having the second medium porosity each have an average pore size of 10 to 300 pm and the average pore sizes. formed during the spraying steps. An article comprising: a body including at least one sliding surface wall having a longitudinal axis and including a covering extending along the longitudinal axis and having a coating thickness; the coating is provided with a central region and an end region, and a plurality of pores dispersed within the coating thickness, the central region is provided with a different average porosity from the end region. Spray coating equipment comprising: a spray torch having variable coating parameters; a controller configured to vary variable coating parameters to produce a coating having variable porosity over a coating length and / or depth.