BR102012025551A2 - CYLINDER SHIRT FOR ENGINING ON AN ENGINE BLOCK AND ENGINE BLOCK - Google Patents

Abstract

CYLINDER SHIRT FOR CHAIN ON AN ENGINE BLOCK AND ENGINE BLOCK "The present invention relates to a cylinder liner (10) choked by casting on an engine block (8), the outer surface (2) being circumferential being provided with a coating (5) capable of promoting adhesion between the cylinder liner (10) and the engine block (8) inhibiting the formation of voids (4) and promoting excellent thermal exchange for the engine block (8) The coating (5) as a particular feature consists of a composite material formed of a matrix equipped with a conductive component (6) involving an adhesive component (7) and the conductive component (6) has a melting temperature higher than that of the metal of the engine block (8) and the melting temperature of the adhesive component (7) is equivalent to that of the metal of the engine block (8), the coating (5) comprising 30% to 90% of the conductive component (6) and a thermal conductivity higher than that of the engine block metal (8).

Description

Patent Descriptive Report for "CYLINDER SHEET FOR ENGINE BLOCK AND ENGINE BLOCK".

The present invention relates to an internal combustion engine component, more specifically to at least one cylinder liner set by casting in an engine block, the circumferential outer surface having a coating capable of promoting adhesion between the shirt and the engine block.

Description of the Prior Art Due to the new market demands, the components

Engine internals are subjected to greater demands and, therefore, need to provide solutions capable of ensuring better performance, as well as contributing to greater engine reliability and performance.

Several automotive component manufacturers are looking for different technical solutions, notably for internal combustion engine cylinder liners, among others. Note that the cylinders of internal combustion engines may be formed by cylinder liners which are set into the engine block by casting the engine block around the circumferential outer portion of the liners.

Regardless of the technical solution applied,

Beautiful internal combustion engines are engine components that suffer significant wear due to the type of work they perform. Among the demands on them are the axial stress of the sleeve inside the cylinder bore and the ability to flow combustion heat to the engine block.

Heat flow and jacket wall thickness are important factors in minimizing thermal and mechanical distortion in operation. Higher distortion engines tend to exhibit higher wear on their components as well as higher levels of oil consumption and pollutant emissions. Thus, increasing heat exchange has several beneficial effects as it prevents excessive component wear and improves fuel, oil and emission conditions. In addition, better heat exchange also reduces block dimensions.

As a rule, cylinder liners are made of ferrous material, especially cast iron, and most modern engine blocks are cast with aluminum or an aluminum alloy, usually containing silicon.

In order to solve the problems inherent in cylinder liner internal combustion engine technology, German document DE19729017 discloses a cylinder liner whose outer surface has axial undulation to lock it in the engine block. Additionally, the document points to the use of a thermal spray process for forming a coating on the outer surface of the cylinder liner. Such coating is comprised of an aluminum silicon alloy (AI-Si) having a Si content of less than 15%. 15 According to the German document, the external surface of the

The cylinder shell may receive said AISi layer directly, or alternatively, may have deposited an intermediate bonding layer. In addition, a thin layer of zinc may be deposited after the AISi layer to provide oxidation protection. Thus, this document comprises at least one thermally deposited AISi layer, and several other layers may be applied both before and after the AISi layer.

It should be noted, however, that the solution presented by the German document fails to solve one of the typical problems resulting from the leaking of the engine block alloy over the cylinder liners. Firstly, although there is a concern in trying to find some chemical parity with the engine block alloy coating by using an aluminum layer with up to 15% silicon, the coating is performed in homogeneous layers, each with a 30 distinct thermal expansion coefficient. Such a configuration has the disadvantage that as liquid metal is poured into the engine block mold and surrounds the cylinder liners, it begins to cool causing the shrinkage thereof. Such contraction is naturally distinct from the deposited layer and the cylinder in ferrous material, which eventually causes the presence of casting defects (voids - see reference 4 in figure 5) in the region of the engine block adjacent to the cylinder liners.

These casting defects, hereinafter referred to as or void

The major drawback is that it impairs the correct heat exchange from the combustion that occurs inside the cylinder to the engine block, increasing thermal distortion and leading to early engine wear or even geariness. .

United States patent US7757652 also discloses a single

a solution to the association between a cast iron cylinder liner and an aluminum engine block. This document makes use of a cold spray application of a metal layer of aluminum, aluminum alloy, copper or copper alloy that is deposited on the outer surface of the cylinder liner.

The major focus of the technology presented by the US document concerns the formation of a specific roughness in the deposited layer for better adhesion with the engine block. Although the document states that the deposited layer is highly thermally conductive, this solution, as in the above-mentioned German document, makes use of a layered coating with different rates of thermal expansion, which will also cause voids in the molten metal and therefore a less efficient heat exchange. Thus, patent technology US7757652, while achieving adhesion between the cylinder liner and the engine block, cannot guarantee good heat exchange also due to defects appearing at or near the interface between the molten material and the liner.

Japanese prior art document JP2008008209 discloses a hybrid jacket that receives a thermal spray-sprayed AISi layer. The production of the engine block containing one of these liners (coated only with AISi) occurs through a pressure casting method, ie there is a press that promotes the pressurization of the liquid metal. Thus, this (liquid) metal is cast at a melting temperature close to the 'Iiquidus' line of the AISi phase diagram, as the time for solidification of the liquid metal must be greatly reduced. Otherwise, the thermal sprinkling layer would be all liquid and the benefits of applying an AISi layer would be lost by appearing the typical defects that impair the heat exchange required for the engine to function properly. In any case, by making use of a solid layer of AISi, this document cannot promote a good thermal expansion gradient nor guarantee an excellent anchorage that allows for greater heat exchange, as it will be seen that a spongy structure '(composite) can achieve. In addition, the technology revealed by this Japanese document only allows high pressure die cast production and does not allow the use of gravity casting. It should also be noted that this technology does not allow temperature flexibility of the block forming molten metal as compared to the composite matrix of the present invention, which has a considerably higher melting point than the temperature of the liquid material added to the casting mold.

Whatever the state of the art solution using deposited layers may improve the anchor condition of the cast iron cylinder compared to a solution without any material. However, a better result will be obtained by using specific materials with adequate thermal expansion coefficients to avoid voids during cooling and shrinkage of the engine block molten metal.

Note that this problem will occur to a greater or lesser extent,

even with the selection of materials with suitable thermal expansion coefficients. Thus, the technical solution is not just a proper choice of the chemical composition of the coating. Furthermore, any of the coatings presented by the prior art makes use of a metal or alloy comprising several elements in different amounts. Coating with such layers also does not contribute to a void-free engine block as the alloy or metal behaves homogeneously across the entire outer surface of the cylinder. In other words, when the liquid metal of the engine block contacts the surface of the liner, a temperature gradient occurs inside the liner to the jacket and such a gradient has a homogeneous behavior because it is the same material throughout the liner. . In turn, the liquid metal on finding a cooler surface initiates the solidification cycle, first around the cylinder liner and then toward the outer portion of the engine block. As cooling takes place and the mold cavity is already filled with the molten metal, the shrinkage generates voids in the regions with the highest cooling gradient and interface with other elements, ie the cylinder liners.

Because of this, although it is possible to ensure a good adhesion of the cylinder liner with the engine block, heat exchange problems still occur due to the voids present in the engine block, as shown in figures 2, 3, 4 and 5

Therefore, a technical solution has not yet been found that is capable of providing excellent adhesion between the cylinder liner and the engine block, without the presence of voids that prevent a good heat exchange with the engine block and ensuring high durability. internal combustion engines.

Objectives of the Invention

It is therefore an object of the present invention to provide a cylinder liner with a coating capable of inhibiting the formation of voids in the engine block due to its solidification, ensuring excellent adhesion and consequently good heat exchange between the combustion chamber and the engine block.

It is also an object of the invention to provide a cast iron cylinder liner provided with a copper (Cu) -containing composite material and a solid-state silicon aluminum alloy (AISi) coating, which is cold-sprayed { cold spray).

It is a further object of the invention to provide a cylinder liner having a thickness of between 20 and 300 microns, comprising 30% to 90% of a conductive component having a higher melting temperature than the engine block molten metal and remaining amount of the melting point equivalent to that of the engine block molten metal.

Brief Description of the Invention

The objects of the present invention are achieved by forming a crimping cylinder liner in an internal combustion engine block, the cylinder liner comprising a cylindrical metal body provided with a circumferential outer surface surrounded by a coating deposited on the outer surface. circumferential of the cylindrical body, the coating comprising a cold spray solid state composite material for forming a matrix composed of a conductive component and an adhesive component, the conductive component having a melting temperature greater than that of the engine block metal and the melting temperature of the adhesive component is equivalent to that of the engine block metal, the coating comprising 30% to 90% of the conductive component and a higher thermal conductivity than the engine block metal .

The objects of the present invention are further achieved by providing an engine block for internal combustion comprising at least one cylinder liner as defined above.

Brief Description of the Drawings

The present invention will hereinafter be described in more detail based on the exemplary embodiments shown in the drawings. The figures show:

Figure 1 is a perspective illustration of a

cylinder;

Figure 2 is a photograph of a circumferential section of a cylinder liner set in a prior art engine block;

Figure 3 - is a photograph of a section of a city shirt.

lindro set in a state of the art engine block showing in detail the formation of casting defects (voids) in the region adjacent to the liner liner;

Figure 4 is a photograph of a section of a cylinder liner set in a prior art engine block showing in detail the formation of casting (void) defects in the region adjacent to the liner liner;

Figure 5 is a photograph of a section of a cylinder liner set in a prior art engine block showing in detail the formation of casting (void) defects in the region adjacent to the liner liner;

Figure 6 is an illustration of the coating of the present invention.

dog;

Figure 7 is an illustration of the coating of the present invention comparing the thermal expansion, thermal conductivity and melting point values of its elements; and Figure 8 - is a graph illustrating the required weighting of the

composite material to achieve an optimal compromise between adhesion and heat exchange.

Detailed Description of the Figures

In order to correctly understand the present invention, it is necessary to clarify the difference between a metal material, or metal alloy, and a composite material.

In a metallic material, such as aluminum or an aluminum alloy (eg aluminum silicon - AISi), there is always a homogeneous material. In other words, it means that the elements have been merged into a component that can be applied as needed.

Conversely, in the case of a composite material, at least two separate solid state components must coexist, that is, the mixture of the two components forms a matrix comprising the characteristics of component A plus the characteristics of component B. If the composite material is heated above the melting point of both components, there is now an alloy formed by A and B, and the same composite material as defined above is no longer. It should be noted that the composite material is to be understood as a heterogeneous mixture of materials, in which one of the materials is not in solid solution, ie that this material participates in the crystal structure of one second.

Such composite material can be obtained by a cold spray process, and it is possible to obtain the phase mixture without solid solution, due to the reduced working temperature.

Due to the characteristics of a composite material, special attention must be paid to the process of obtaining it. Thus, the process in question cannot make use of a temperature that underlies one of the components, which could give rise, for example, to a ternary alloy if one works with two compounds, one pure metal and one binary alloy.

Of all known thermal spray processes, it has only recently been possible to achieve a spray temperature of less than 15 600 ° C by the cold spray method. This is, of course, one of the reasons why it would not be possible previously to conduct research in the present technological field, more particularly in the possibility of creating composites for the deposition of cylinder liners 10.

The present invention thus makes use of a thermal spray process, more particularly cold spray, also known as metallization, whose processing temperatures are guaranteed to be below 600 ° C.

Having understood the formation of a composite material, it is necessary to explore the features of the present invention. As explained, the field of the present invention relates to internal combustion engines, more particularly the interaction between cylinder liners 10 and respective engine block 8 in which they are set by pouring liquid metal around cylinder liners. previously arranged in the respective mold. Typically, the engine block metal is a lightweight metal, such as aluminum or an aluminum alloy.

The cylinder liner 10, as stated, needs to ensure its adhesion to the engine block 8, as well as to ensure that, after cooling of the molten liquid metal in the mold, no metal-free voids 4 (casting defects) appear. As explained in the prior art, ensuring this combination is complex.

As shown in Figure 1, a cylinder liner 10 is provided with a hollow tube or cylindrical body 1, generally consisting of a ferrous alloy such as cast iron or gray cast iron. This cylindrical body 1 imparts two particular surfaces, the inner surface 3 where axial movement of a piston will occur and the circumferential outer surface 2. It is this outer region that will be surrounded by the liquid metal of the engine block 108, but only after the outer surface 2 has been coated 5, the present invention being configured.

As explained, the coating 5 of the present invention is applied directly to the outer surface 2 without special preparation, being made of a composite material comprising at least two distinct compounds and at least one of these materials may be an alloy. The combination of compounds is weighted according to the behavior shown in Figure 8. Thus, it is ideal that a compound promotes good adhesion (behavior identified by the letter B) between the pair, cylinder liner 1 and engine block 8. , called the adhesive component 7, 20 and the other compound has good thermal conduction (behavior identified by the letter A), called the conductive component 6. The void problem 4, as will be seen below, is solved by the composite formation of the coating 5.

The best relationship between conductive component 6 and adhesive component 7 is achieved when the conductive component is present in coating 5 in a ratio of 30% to 90%, preferably 55% to 90%. The remainder will be filled in by the adhesive component 7. It should be noted that one or more conductive components 6 and adhesives 7 may be used, provided that the mentioned ratio is maintained. In turn, each component may consist of a metal or alloy.

Preferably, but not obligatory, the present invention is represented by FIG. 6 showing a cylinder liner 10 in section. The cylinder liner 10 of the present invention thus comprises a gray cast iron cylinder body 1 provided with a coating 5 composed of a copper (Cu) conductive component 6 or its alloys and an aluminum adhesive component 7 or its alloys, such as cold spray aluminum silicon alloy (AISi), the cylinder liner 10 being enclosed by the engine block 8 consisting of an aluminum alloy such as, for example, an alloy aluminum silicon (AISi).

As is readily apparent, the adhesive component 7 guarantees its adhesion function on account of the chemical parity with the alloy of the engine block 8. On the other hand, the conductive component 6 drains the heat from combustion easily because it is composed of the copper metal, famously known as a thermally conductive material. Of course, depending on the alloy of the engine block 8, the composite material of the cladding 5 may be comprised of other materials, since what is desired here is the relationship between chemical parity and heat transfer.

It should also be noted that the composite material of the present invention (formed, for example, by the conductive and adhesive components 6,7 Cu and AISi, respectively) has an intermediate thermal expansion coefficient 20 to that of the cylinder liner material 10 (e.g. iron) and that of the engine block alloy 8 (eg AISi) - see Figure 8. Gradation of the coefficient of expansion prevents defects (cracks and voids 4) due to cooling in the region adjacent to the material interface of the cast engine block 8 (AISi). This beneficial effect is enhanced by improved heat transfer due to the presence of copper matrix in the composite. This better heat transmission minimizes the thermal gradient, which in turn eliminates shrinkage defects (cracks and voids 4) during solidification and subsequent cooling of the material. Note that the thermal conductivity of coating 5 should be considered to be at least 250 W / (mK).

For a better understanding, figure 7 illustrates the different values

thermal expansion, thermal conductivity and melting point of the engine block 8, jacket 10 and liner. With a similar distribution as noted, the thermal expansion of the conductive member 6 minimizes fractures and defects adjacent to the jacket 10 cast iron substrate. In turn, the engine block metal 8 generates localized fusion of the adhesive member 7 of the jacket 5 , which promotes an increase in surface area 5 for heat exchange. Accordingly, composite liner 5 improves adhesion and thermal conduction due to the integration of interfaces between cylinder liner 10 and liner 5.

As discussed above, there is a balance between the quantities of each component 6, 7 used and this relationship is deeply rooted in the formation of the composite material.

The formation of the composite material occurs by particle bombardment of each of the components on the outer surface 2 of the cylinder liner 10 provided by the spray method. When each particle reaches the outer surface, it undergoes a very high deformation and must remain in a solid state. This is a limiting factor in the choice of components 6, 7 as they need to have high ductility and plasticity.

As shown in the graph of figure 8, the conductive component 6 is preferably deposited in greater quantity, the adhesive component 20 being located within the conductive component 6. For a better understanding of what the composite material looks like if possible removing all the adhesive component 7 would have a porous structure formed by the conductive component 6 which would allow communication between its voids. In addition, the conductive component 6 must have a melt temperature higher than that of the engine block metal 8 and the melt temperature of the adhesive component 7 should be substantially equivalent to that of the engine block metal 8.

Understanding the composite structure is of the utmost importance as it allows one to understand what occurs during the casting of the liquid metal of the engine block 8 containing at least one jacket of the present invention. Thus, there are two metals with similar melting points, they are the adhesive component 7 and the liquid metal of the engine block 8, both in an aluminum silicon alloy (AISi). In turn, the conductive component 6, being copper (Cu), has a melting temperature higher than aluminum silicon alloy (AISi). This respects the conditions of the present invention.

What occurs during casting is that the liquid metal of the engine block 8, upon contact with the casing 5, promotes its heating, causing at least partially the melting of the adhesive component 7, either by direct contact or by by the high heat transfer that copper allows. Since the adhesive component alloy 7 has high chemical parity with the engine block alloy 8, the adhesion is very high. At the same time, the adhesive component alloy 7 communicates with each other, which allows the liquid metal adhesion of the motor block 8 to be rooted within the structure of the conductive component 6, i.e. throughout its thickness. This double adhesion (chemical parity and rooting in the structure of the composite material) ensures very high adhesion by making a combined use not previously experienced.

With respect to the thickness of the coating 5 of the present invention, it may range from 20 to 300 microns. In addition, the coating 5 will have a roughness as deposited.

Contrary to the prior art which was concerned only with chemical parity or roughness, the presence of a composite coating 5 of the present invention allows to control the anchoring process of the liners along the depth of the block casting by allowing the study of a coating. as a function of the quantity of each component 6,7, its deformability, thermal conduction and chemical parity with the engine block metal 8.

The state of the art has never worked with this tripartite relationship, much less when such relationship converges to the formation of a composite liner 8, the characteristics of which allow perfectly to accommodate the contractions resulting from the cooling of the liquid metal of the 30 motor block 8 without formation occurring. Thus, not only is this disadvantage overcome, but the jacket itself is able to better flow heat during engine operation by the engine block 8 by having a more conductive coating that acts as a heatsink between the different materials that make up the set in comment.

The technical solution of the present invention, by contributing to a better heat flow and reducing the wall thickness of the jacket, allows the minimization of thermal and mechanical distortions in the operation of the engine. 8. Higher distortion motors tend to have higher wear of its components as well as higher levels of oil consumption and pollutant emissions. Thus, increasing heat exchange has several beneficial effects as it avoids excessive component wear and improves fuel, oil and emission conditions. In addition, better heat exchange also reduces block dimensions (interbore), resulting in more compact and therefore lighter motor blocks.

Having described examples of preferred embodiments, it should be understood that the scope of the present invention encompasses other possible variations, being limited only by the content of the appended claims, including the possible equivalents thereof.

Claims (10)

1. Cylinder sleeve (10) for engagement in an internal combustion engine block (8), the cylinder sleeve (10) comprising a cylindrical metal body (1) provided with a circumferential outer surface (2) surrounded by a liner (5) deposited on the circumferential outer surface (2) of the cylindrical body (1), the cylinder liner (10) being characterized by the fact that the coating (5) comprises a cold spray applied solid state composite material spray) for forming a matrix composed of a conductive component (6) and an adhesive component (7), the conductive component (6) having a melting temperature higher than that of the engine block metal (8) and the temperature The melt of the adhesive component (7) is equivalent to that of the engine block metal (8), the coating (5) comprising 30% to 90% of the conductive component (6) and a higher thermal conductivity than the engine block metal. (8). Cylinder jacket (10) according to claim 1, characterized in that the spraying occurs at a temperature of a maximum of 600 ° C. Cylinder liner (10) according to claim 1, characterized in that the thermal conductivity of the liner (5) is at least 250 W / (mK). Cylinder sleeve (10) according to claim 1, characterized in that the shell (5) has an adhesive force on the cylinder sleeve (10) and the engine block (8) of more than 10 MPa. Cylinder sleeve (10) according to Claim 1, characterized in that the conductive component (6) is formed of copper (Cu) and its alloys, the adhesive component (7) is formed of aluminum and its alloys. and the engine block (8) is formed of aluminum or an aluminum alloy. Cylinder jacket (10) according to claim 1, characterized in that the coating (5) comprises 55% to 90% of the conductive component (6), preferably 60% to 85% of the conductive component (6). 6). Cylinder jacket (10) according to claim 1, characterized in that the coating (5) comprises a thickness ranging from 20 to 300 microns. Cylinder jacket (10) according to claim 1, characterized in that the coating (5) has a roughness as deposited. Cylinder sleeve (10) according to Claim 1, characterized in that the cylindrical body (1) is of a ferrous alloy, preferably of gray cast iron. An internal combustion engine block, characterized in that it comprises at least one cylinder liner as defined in claim 1.