Patent Grant
7290506
The invention generally relates to cooling or preheating internal combustion engines, and more particularly to cooling or preheating cylinder liners by passing fluids through internal passages in the cylinder liners.
A direct result of the increased horsepower of modern automotives engines is the proportional increase in the heat generated by these engines. The heat generated by internal combustion engines tends to degrade many of the components of the engine. The high heat at which these engines run also tends to increase emissions, especially of nitrogen oxide. The Environmental Protection agency and the Corporate Average Fuel Efficiency (“CAFE”) standards adopted by the Department of Transportation has identified the reduction of nitrogen oxide as one of their goals. In order to address the CAFE standards and the negative impact of the increased heat generation in today's high horsepower engines, automotive manufacturers have had to resort to increasingly complex cooling systems for these engines. The complexity of these cooling systems has increased not only the expense of manufacturing these engines, but also their weight and the potential for flaws in the cooling system—both during manufacture and while in use.
Three components or regions of the internal combustion engine where heat is concentrated are the combustion chambers, cylinder bores, and pistons. To cool these regions or components, internal combustion engines are designed with numerous passages through which fluids—oil, water, coolants, or gases (e.g., air)—are circulated to draw heat away from the engine block. Furthermore, engine designs incorporate cylinder liners to avoid degradation of the cylinder bores caused by heating and cooling. A cylinder liner, typically made of ductile iron, is a hollow cylinder whose outside diameter is close to the internal diameter of the cylinder bore, so that the liner fits inside the cylinder bore snugly. The piston travels inside the cylinder liner, thus heating up the cylinder liner first instead of directly transferring its heat to the cylinder bore and the engine block itself. The use of cylinder liners helps alleviate degradation of the cylinder bore due to the heat, but in turn creates problems related to degradation of the cylinder liners due to excessive heating. Thus, cylinder liners are a fourth component of internal combustion engines that are subject to degradation and failure due to excessive heating. Because cylinder liners are such an integral part of the design of internal combustion engines and because they play such a crucial role in avoiding degradation of the engine block itself, various techniques have been developed expressly to address the cooling of cylinder liners in today's high horsepower engines.
Cylinder liners can be either of the dry-sleeve or wet-sleeve design. In a wet-sleeve design, a cooling medium is present between at least part of the interior surface of the cylinder bore and the outer surface of the liner. The engine block is designed with a complex series of passages for this cooling medium to be brought in contact with the liner and then removed to a heat exchange location (e.g., a radiator) where the medium can release the heat it drew from the cylinder liner and cylinder bore. In a dry-sleeve design, the outer surface of the liner and the interior surface of the cylinder bore are for the most part in direct contact. Although there is no fluid present between the interior surface of the cylinder bore and the outer surface of the cylinder liner, fluids are still circulated within the engine block, through a complex series of passages, to draw heat away from the cylinder bore and the cylinder liner. The complexity of the layout of the passages and process of circulating the cooling medium uniformly round all of the cylinder bores is especially accentuated in engines where the cylinder bores are arranged in a “V”-formation (e.g., V-8s and V-12s) because these engines tend to have reservoirs for the cooling medium arranged on one-side of the engine; necessitating a complex series of passages to circulate fluids to the other side.
In some engines, oil is squirted through a small tube or plurality of tubes into the bottom of the cylinder bore and allowed to hit the bottom of the piston. The oil that is squirted in, using these “oil squirters” or “piston squirters,” cools down the piston and increases lubrication. Piston squirters are not incorporated as part of the system of passages that carry the cooling medium but instead are incorporated as separate systems dedicated only to transporting oil from the oil-pan to the bottom of the cylinder bore.
In addition to the increased cost of engine block design and manufacture necessitated by the current dry-sleeve or wet-sleeve design, a primary shortcoming of the wet-sleeve design is the non-uniform distribution of the cooling fluid surrounding the cylinder liner. The non-uniform distribution leads to uneven cooling of the liner, the development of hot spots, and the eventual cracking or failure of the liner. Prior art wet-sleeve designs have attempted to address this problem by changing the shape and structure of the outer surface of the cylinder liner (e.g., U.S. Pat. No. 6,675,750 to Wagner). However, while this design increases the surface area of the liner that is exposed to the cooling medium, it fails to address the problem of non-uniform distribution of the cooling fluid because the fluid is not in contact with the entire axial length of the liner.
This design also does not reduce the requirement for a complex series of passages within the engine block for circulating the cooling medium to and from the area between the cylinder bore and the cylinder liner. Furthermore, the design increases the complexity and manufacturing cost of producing cylinder liners by changing the typically planar outer surface of the liner to “an outer surface with a plurality of peaks and valleys” (see U.S. Pat. No. 6,675,750 patent, at col. 2, 11, 15-16).
Additionally, while the above-described designs and approaches are directed at cooling the cylinder areas, they do not address the problem presented by engine ‘cold-start’ and idle periods; during which times substantial excessive pollution/emissions are generated because the cylinders are not at an appropriate temperature to provide for optimally efficient combustion. This is a serious problem in the trucking industry, and has led to increasingly more stringent regulations regarding idling periods. Therefore, the above-described prior art efforts to improve cooling of cylinder liners actually create additional problems from the standpoint of pollutants being generated during cold-starting and idling.
There is, therefore, a pronounced need in the art for cylinder liners that are cost effective and easy to manufacture, allow uniform distribution of cooling fluids along their axial length, and facilitate the design of simpler engine blocks with less complicated passages for circulating cooling fluids. There is also a pronounced need in the art for piston squirters integrated into the circulation system for cooling the cylinder liner and cylinder bore, to preclude the need for an entirely separate squirter circulation system. Moreover, there is a pronounced need for cylinder liners that allow for different cooling fluids (e.g., oil and water, or oil and ethylene-glycol, or water and a compressed inert gas such as nitrogen) to be independently circulated through the liner. Where oil is used as the liner cooling medium, there is also a need for cylinder liners that allow for the oil to circulate within a closed loop, thus avoiding directing oil on to the crankshaft. Oil directed (e.g., dripped) on the crankshaft leads to increased emissions and peristaltic drag, thus a design that eliminates direction of oil onto the crankshaft decreases emissions as well as peristaltic drag. Furthermore, there is a pronounced need in the art for cylinder liners with enhanced thermal conductivity to improve heat transfer/dissipation. Finally, there is a pronounced need in the art for cylinder liners that have enhanced electrical conductivity to allow for thermoelectric heating of the cylinder liners during engine warm-up, particularly in larger engines such as, but not limited to diesel engines of, for example, trucks and the like. There is a need to shorten warm-up periods and reduce pollution, while still providing for cooling and enhanced engine life.
Particular embodiments of the present invention provide for novel fluid-cooled cylinder liners, comprising a generally annular cylindrical member having top and bottom cylinder ends, and having parallel or generally parallel inner and outer surfaces. The cylinder member comprises a fluid channel integrated within and between the surfaces of the member, wherein the channel has a first and a second ends. Additionally, there are first and second channel openings at or near the first and second channel ends, respectively, wherein one channel opening opens to at least one of a cylinder end and the outer cylinder surface, wherein the other channel opening opens to at least one of a cylinder end, the other cylinder end, the outer cylinder surface, and the inner cylinder surface, and wherein the channel and channel openings define a fluid passageway. Preferably, the cylinder liner comprises a plurality of separate fluid channels. Preferably, the cylinder liners further comprise a flange at the top cylinder end, the flange suitable to be received into a counterbore in a cylinder bore. Preferably the cylinder liner comprises at least one of aluminum and aluminum alloy, or consists of or comprises at least one material selected from the group consisting of: aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALCAN®, containing silicon carbide, and manufactured by Alcan Aluminum Limited); superalloys; ceramic matrix composite (CMC); ‘carbon graphite foam’; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%). Preferably, the cylinder liner comprises MMC, CMC or carbon graphite foam, with at least one of silicon carbide, and silicon nitrate. The cylinder liners can manufactured by standard casting methods. Preferably, infusion casting is used; for example, aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a porous ‘preform’ (e.g., MMC, CMC, ceramic, or carbon graphite foam ‘preform’).
In particular embodiments, the cylinder member comprises a single continuous, integrated, serpentine channel with the channel ends subtended by two openings, wherein the channel traverses substantially throughout the interior surface of the cylinder liner and the channel openings open to at least one of: the same cylinder end; opposite cylinder ends; the outer cylinder surface (both); and to one end (one opening) and the outer surface (the other opening).
In preferred embodiments, the channels comprise a third opening positioned along the channel somewhere between the first and second openings, wherein the third opening opens to the outer cylinder surface. Preferably, such embodiments further comprise a fluid-directing tube connected to a channel opening in the bottom cylinder end.
Preferably, the cylinder liners comprise a plurality of channels all having one channel opening at the same cylinder end, and all having one channel opening at the outer cylinder surface near the other cylinder end, and positioned in a circular arrangement running parallel to the cylinder ends. Preferably, such embodiments further comprise two circular groves on the outer surface of the cylinder liner parallel to the arrangement of openings on the outer surface suitable to receive sealing means (e.g., O-rings).
In yet further embodiments, the cylinder liners further comprising a plurality of channels and a circular trough perpendicular to the cylinder axis and recessed into the outer cylinder surface, wherein a plurality of channel openings open into the trough to form a circular arrangement of channel openings within the trough.
In particularly preferred embodiments, the cylinder liner comprises ‘carbon graphite foam’. Preferably, infusion casting is used. For example, an aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a ‘preform’ of porous ‘carbon graphite foam’ (with or without particulate reinforcement, such as silicon carbide). Carbon graphite foam (developed at Oak Ridge National Laboratory, USA) has high thermal conductivity and also acts as super-conductor (see, e.g., U.S. Pat. Nos. 6,673,328, 6,663,842, 6,656,443, 6,398,994, 6,387,343 and 6,261,485, all of which are incorporated by reference herein in their entirety). Preferably the silicon carbide volume should be from about 10% to 35% to provide desired friction at wear plate rubbing surface. Infiltration of un-reinforced or reinforced alloy into carbon graphite foam ‘preform’ is during a suitable casting procedure including, but not limited to die casting, high-vacuum permanent mold casting, squeeze casting, or centrifugal casting. According to the present invention, carbon graphite foam can be included in the compositions of at least one of the cylinder liner, and any parts in contact therewith. According to the present invention, the use of carbon graphite foam ‘preforms’ not only substantially reduces manufacturing costs (e.g., relative to the use of ceramic ‘preforms’), but provides an environmentally responsible cylinder liner, because carbon graphite foam is manufactured from a by-product of coal fabrication.
In preferred embodiments the cylinder liner comprises carbon graphite foam, and additionally comprises, or is in communication with at least one heating element (e.g., electrical resistive element), which is optionally in communication with external controller means, to allow for heating, or regulated heating of the cylinder liner (e.g., prior to or during engine cold-start periods, and/or idling periods).
Particular embodiments of the present invention provide novel fluid-cooled cylinder liners. Preferred liners are generally in the shape of annular cylinders and contain a plurality of passages; arranged parallel to the axis of the cylinder, between the inner and outer surfaces of the cylinders. Preferred passages are arranged so that they are typically closer to the outer surface of the cylinder than the inner surface. Each passage has at least two openings. Openings that appear at either end of the cylinder are referred to herein as “ports,” whereas those that appear along the inner or outer surface of the cylinder are referred to herein as “windows.” Thus, a passage with two ports (with one on either end of the cylinder) would run the entire length of the cylinder, while a passage with a port and a window or a passage with two windows would run only for a fraction of the cylinder length. Although windows can be arranged at any position along the outer or inner surfaces of the cylinder liner, in the preferred embodiments windows will be arranged along the outer surface of the cylinder liner, in a circle lying on a plane perpendicular to the axis of the liner, and close to either end of the liner; ensuring that each passage with windows traverses the majority of the length of the cylinder. Other embodiments of the invention contain a plurality of passages parallel to each other but traveling in a spiral path within the cylinder surfaces. Embodiments could also include a plurality of “short” passages aligned along a line parallel to the axis of the cylinder with each passage covering only a short fraction of the length, but the plurality of passages lying along one such line serving the role of one of the longer passages in the preferred embodiments. Further embodiments incorporate windows within the inner surface of the cylinder liner, allowing for the cooling medium (possibly oil) to drain into the cylinder bore below the piston rings.
Ports along the “top” of in the cylinder liner, that is, along the end of the cylinder liner closest to the combustion chamber, would be aligned with conforming openings in the cylinder head. Ports along the “bottom” of the cylinder liner would either open into the cylinder bore or be aligned with openings along a “step” in the cylinder bore on which the cylinder liner would sit. As is true in the prior art, the cylinder head and the top of the cylinder liner would be preferably separated by a gasket and in embodiments incorporating a step, the cylinder liner bottom and the step would preferably be separated by a gasket. Such gaskets have gasket windows appropriately aligned to create passages from the cylinder head into the cylinder liner or the cylinder liner into the engine block respectively.
In preferred embodiments, cylinder liners with windows along the outer surface are aligned with openings into passages within the engine block. Preferably, each circular arrangement of windows along the outer liner surface is located between two circular groves on the outer surface of the cylinder liner, the groves being parallel to the circular arrangement of windows. Preferably, O-rings are inserted into these groves, with part of the O-ring extending beyond the outer surface of the cylinder liner, so that when the liner is inserted into a cylinder bore a sealed, annular region is formed; bound by the O-rings, the outer surface of the cylinder liner, and the interior surface of the cylinder bore.
A different embodiment of the invention includes a shallow, circular trough along the outer surface of the cylinder liner, lying on a plane perpendicular to the axis of the cylinder. Windows are arranged in a circle along the center of the trough, and a band containing a plurality of openings each opening surrounded on each side of the band by O-rings would fit therein. Preferably, the band is the same width as the width of the trough, and has the same thickness as the depth of the trough, so when the band is placed within the trough its outer surface coincides with the outer surface of the cylinder liner. The plurality of band openings are equal in number to the windows within the trough, and are arranged so that an opening (which could be slightly larger than a window) fits over each of the windows. In this embodiment, the windows are aligned with openings for passages within the engine block with the gaskets on the band creating a seal for each window-passage opening alignment, thus creating separate, sealed passages between the cylinder liner and the engine block. In particular embodiments, different fluids are transported by different passages without the fluids intermingling.
Passages allow cooling media to circulate through the cylinder liner. Depending on the direction of flow, the cooling media could: enter or exit into the cylinder head (in embodiments in which ports on top of the cylinder liner are aligned with openings for passages within the cylinder head); enter or exit into the engine block (in embodiments in which windows are aligned with openings for passages in the engine block or in which the cylinder liner has ports along the bottom aligned with openings in a step on which the cylinder liner sits); or drain into the cylinder bore and eventually into the oil-pan (in embodiments in which the cylinder liner has ports along the bottom and the cylinder liner is not sitting on a step). Depending on the configuration of passages, the cooling media could be oil, water, ethylene-glycol, or gas (including air or a compressed inert gas such as nitrogen) or a combination of media carried in different passages separated from one another by appropriate sealed regions.
In preferred embodiments, one or more of the ports along the bottom of the cylinder liners are configured to receive generally U-shaped tubes that direct oil towards the interior of the cylinder bore. In such embodiments, the cylinder liner incorporates one or more piston squirters that do not rely on a separate circulation system.
Preferably the cylinder liner comprises at least one of aluminum and aluminum alloy, or consists of or comprises at least one material selected from the group consisting of: aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALCAN®, containing silicon carbide, and manufactured by Alcan Aluminum Limited); superalloys; ceramic matrix composite (CMC); ‘carbon graphite foam’; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%). Preferably, the cylinder liner comprises MMC, CMC or carbon graphite foam, with at least one of silicon carbide, and silicon nitrate. The cylinder liners can manufactured by standard casting methods. Preferably, infusion casting is used; for example, aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a porous ‘preform’ (e.g., MMC, CMC, ceramic, or carbon graphite foam ‘preform’). Alternatively, embodiments could be made of other materials including ductile iron.
In particular embodiments, the cylinder liners consist of, comprise, or substantially comprise a material selected from the group consisting of carbon graphite foam, ceramic matrix composite (“CMC”) having a two- or three-dimensionally interconnected crystalline ceramic phase and a non-contiguous metal phase dispersed within the interconnected ceramic phase (see, e.g., U.S. Pat. Nos. 5,620,791, 5,878,849 and 6,458,466, all of which incorporated herein by reference in their entirety), and combinations thereof.
The ceramic phase of the CMC may be a boride, oxide, carbide, nitride, silicide or combination thereof. Combinations include, for example, borocarbides, oxynitrides, oxycarbides and carbonitrides. The ceramic may include various dopant elements to provide a specifically desired microstructure, or specifically desired mechanical, physical, or chemical properties in the resulting composite. The metal phase of the CMC may be a metal selected from the Periodic Table Groups 2, 4-11, 13 and 14 and alloys thereof.
In particular embodiments, the CMC is produced by infiltrating a porous ceramic body with a metal, thus forming a composite. Such infiltration involves, for example, forming a porous ceramic ‘preform’ prepared from ceramic powder, such as in slip casting (e.g., a dispersion of the ceramic powder in a liquid, or as in pressing (e.g., applying pressure to powder in the absence of heat), and then infiltrating a liquid metal into the pores of said preform.
In particular embodiments, the material comprises a ceramic-metal composite comprised of a metal phase and a ceramic phase dispersed within each other, wherein the ceramic phase is present in an amount of at least 20 percent by volume of the ceramic-metal composite. In particular embodiments, the braking component is a metal substrate, such as aluminum, having laminated thereto a ceramic metal composite of a dense boron carbide-aluminum composite having high specific heat and low density.
In particularly preferred embodiments, the cylinder liner comprises ‘carbon graphite foam’. Preferably, infusion casting is used. For example, an aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a ‘preform’ of porous ‘carbon graphite foam’ (with or without particulate reinforcement, such as silicon carbide). Carbon graphite foam (developed at Oak Ridge National Laboratory, USA) has high thermal conductivity and also acts as super-conductor (see, e.g., U.S. Pat. Nos. 6,673,328, 6,663,842, 6,656,443, 6,398,994, 6,387,343 and 6,261,485, all of which are incorporated by reference herein in their entirety). Preferably the silicon carbide volume should be from about 10% to 35% to provide desired friction at wear plate rubbing surface. Infiltration of un-reinforced or reinforced alloy into carbon graphite foam ‘preform’ is during a suitable casting procedure including, but not limited to die casting, high-vacuum permanent mold casting, squeeze casting, or centrifugal casting. According to the present invention, carbon graphite foam can be included in the compositions of at least one of the cylinder liner, and any parts in contact therewith. According to the present invention, the use of carbon graphite foam ‘preforms’ not only substantially reduces manufacturing costs (e.g., relative to the use of ceramic ‘preforms’), but provides an environmentally responsible cylinder liner, because carbon graphite foam is manufactured from a by-product of coal fabrication.
In preferred embodiments the cylinder liner comprises carbon graphite foam, and additionally comprises, or is in communication with at least one heating element (e.g., electrical resistive element), which is optionally in communication with external controller means, to allow for heating, or regulated heating of the cylinder liner (e.g., prior to or during engine cold-start periods, and/or idling periods).
These cylinder liners, and particularly those comprising carbon graphite foam, allow for more efficient cooling over prior art liners by allowing the cooling media to be in direct contact with the engine components where there is the greatest heat concentration; that is, in the cylinder liner. Preferably, the passages run the entire, or almost the entire length of the cylinder liners, and the inventive designs facilitate uniform cooling of the cylinder liners; avoiding hot spots that can lead to cracking and degradation of cylinder liners.
Additionally, by creating passages for the cooling media to pass through in direct contact with the cylinder liner, these cylinder liners reduce or eliminate the need for a complex series of passages within the engine block; a concomitant feature of prior art wet-sleeve and dry-sleeve cylinder liners. This reduction in passages within the engine block has a number of advantages, including but not limited to, ease and cost effectiveness of manufacture of engine blocks, the ability to cast more compact and lighter engine blocks and pistons, and lessening of the potential of failure of the cooling system during manufacture or during its operation.
By including the passages for the cooling media within the cylinder liner itself, this innovation overcomes the absence of uniform cooling present in prior art wet-sleeve design, and particularly in “V”-formation engines where the cooling medium reservoir is typically asymmetrically located.
The presence of the cooling media where it is most efficient in reducing overall engine heat means that a engine will run cooler and there will be fewer emissions, especially of nitrogen oxide.
The increased efficiency in cooling allows automotive manufacturers to utilize less cooling media—not only reducing the space needed to store the cooling media but also significantly decreasing overall weight (an important goal in the race to increase fuel-efficiency in automobiles with high horsepower engines). Unlike traditional wet-sleeve designs, particular inventive embodiments provide for simultaneous use of different cooling media, because the inventive cylinder liners allow for a plurality of independent passages. And, by varying the construction of the passages (two ports, one port and a window, or two windows), the cooling media can be: oil draining into a oil pan; water or coolant under pressure running through the cylinder liner and up through passages in the cylinder head; compressed inert gases such as nitrogen circulating within a closed loop; oil under pressure coming down through the cylinder head and being squirted on to the underside of the piston using a piston squirter, or combinations thereof.
In particular closed loop embodiments, a series of one-way check valves is used to exploit the property of fluids that they expand when heated and contract when cooled, to implement a cooling circuit that does not depend on external forces to circulate the cooling media through the passages.
In particular embodiments, stored heat, or battery—or electrically-driven heating elements in communication with the fluids circulating through the passages in the cylinder liner can also be utilized to pre-warm the liners before the automobile is started; leading to increased fuel efficiency and decreased emissions from not having to “warm up” the engine. In preferred embodiments the cylinder liner comprises carbon graphite foam, and additionally comprises, or is in communication with at least one heating element (e.g., electrical resistive element), which is optionally in communication with external controller means, to allow for heating, or regulated heating of the cylinder liner (e.g., prior to or during engine cold-start periods, and/or idling periods). Therefore, unlike prior art designs directed only at cooling the cylinder areas, aspects of the present invention additionally address the problem presented by engine ‘cold-start’ and idle periods. According to the present invention, the ability to warm or heat, or prewarm or preheat the cylinder liners substantially reduces excessive emissions and pollution otherwise generated because the cylinders are not at an appropriate temperature to provide for optimally efficient combustion. Therefore, not only do the inventive cylinder liners contribute to cooler engines and extended cylinder and engine life, but also address a serious problem in the transportation/trucking industry, and in the environment, and will significantly enable the transportation industry to operate within an increasingly more stringent regulatory environment.
Other embodiments incorporate sensor materials or devices (e.g., magnetic resistive devices) to monitor and manage the flow and temperature of the fluids circulating through the passages in the cylinder liner to optimize the temperature of the cylinder liner and decrease degradation of engine components and lower emissions.
Further, because the inventive cylinder liners are fundamentally cylindrical in shape and do not have complicated outer surface structures, they can be easily manufactured employing commonly-used manufacturing techniques, including die-casting, extrusions, the lost-foam method, or a combination thereof.
Preferably the cylinder liner 222 comprises at least one of aluminum and aluminum alloy, or consists of or comprises at least one material selected from the group consisting of: aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALCAN®, containing silicon carbide, and manufactured by Alcan Aluminum Limited); superalloys; ceramic matrix composite (CMC); ‘carbon graphite foam’; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%). Preferably, the cylinder liner comprises MMC, CMC or carbon graphite foam, with at least one of silicon carbide, and silicon nitrate.
Although slightly more complicated to manufacture than cylinder liner 122 (with reference to
The cylinder liner embodiment of
Preferably the cylinder liner 322 comprises at least one of aluminum and aluminum alloy, or consists of or comprises at least one material selected from the group consisting of: aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALCAN®, containing silicon carbide, and manufactured by Alcan Aluminum Limited); superalloys; ceramic matrix composite (CMC); ‘carbon graphite foam’; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%). Preferably, the cylinder liner comprises MMC, CMC or carbon graphite foam, with at least one of silicon carbide, and silicon nitrate.
Cylinder liner 322 is preferably manufactured by die-casting, the lost-foam method, or a combination thereof. Even more preferably, it is manufactured using infiltration casting of ‘preforms’ comprising or consisting of carbon graphite foam.
This embodiment of the cylinder bore 168 includes a step 164 on which the cylinder liner 422 sits. In order to provide a sealing fit and to prevent wear and tear, a gasket 160 is optionally placed between the bottom 130 of cylinder liner 422 and the step 164.
A passage 146 has an opening in a port 134 along the top 132 of the cylinder liner 422 and another opening in a port 138 along the bottom 130 of the cylinder liner 422. The port 138 is aligned with an opening in the gasket 160 and an opening for fluid passage 180 within the body of the engine block 190. This arrangement creates a passage that incorporates port 134, passage 146, port 138, and passage 180, and runs from the top 132 of cylinder block 422 into the engine block 190. When port 134 is aligned with a opening for a passage in the cylinder head, this arrangement would allow cooling media to flow through the cylinder head, within the surfaces of the cylinder line 422, and into the engine block 190. Or by reversing the flow, it would carry cooling media through the engine block 190, through the surfaces of the cylinder liner 422, and into passages within the cylinder head.
Cylinder liner 422, includes another passage 148 that has one opening in a port 135 along the top 132 of cylinder liner 422 and another opening in a window 140 on the outer surface 124 of cylinder liner 422. Because window 140 is towards the bottom 130 of cylinder liner 422, passage 148 runs almost the entire length of cylinder liner 422, facilitating uniform cooling of the cylinder liner 422 when a cooling medium is circulated through passage 148. Note that there are O-rings 156 and 158 arrayed on either side of 148 and running along the entire outer surface 124 of the cylinder liner 422 parallel or generally parallel to the bottom 130 of cylinder liner 422. O-rings 156 and 158 create a sealed annular region between the outer surface 124 of cylinder liner 422 and interior surface 166 of the cylinder bore. The window 140 is aligned with an opening for a fluid passage 184 that runs within the engine block 190. Because any cooling media circulated through passage 148 would be contained in the sealed, annular region formed by O-rings 156 and 158, the outer surface 124 of cylinder liner 422, and the interior surface 166 of the cylinder bore, the cooling media in passage 148 is optionally different from the cooling media circulated through passage 146.
Preferably the cylinder liners 122, 222, 322 and 422 comprise at least one of aluminum and aluminum alloy, or consists of or comprises at least one material selected from the group consisting of: aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALCAN®, containing silicon carbide, and manufactured by Alcan Aluminum Limited); superalloys; ceramic matrix composite (CMC); ‘carbon graphite foam’; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%). Preferably, the cylinder liner comprises MMC, CMC or carbon graphite foam, with at least one of silicon carbide, and silicon nitrate. The cylinder liners can manufactured by standard casting methods (e.g., by die-casting, the lost-foam method, or a combination thereof). Preferably, infusion casting is used; for example, aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a porous ‘preform’ (e.g., MMC, CMC, ceramic, or carbon graphite foam ‘preform’). Alternatively, embodiments could be made of other materials including ductile iron.
Casting. In particular aspects, the cylinder liners are cast in a mold, by any suitable casting process, including but not limited to die casting, sand casting, permanent mold casting, squeeze casting, or lost foam casting. Preferably, casting is by die-casting. Alternatively, casting of the cylinder liners is by spin-casting, such as that generally described in U.S. Pat. No. 5,980,792 to Chamlee (incorporated herein by reference in its entirety). For example, aluminum-based metal matrix composite (MMC) comprising a particulate reinforcement (e.g., Duralcan®) containing silicon carbide) is centrifugally spin-casted to cause and create functionally beneficial particulate (sic) distributions (gradients). In the present instance such casting methods increase particle density at friction surfaces.
Alternatively, aluminum-based alloys, including eutectic and hypereutectic alloys such as 380, 388, 398, 413, or others such as 359-356-6061, optionally containing particulate reinforcement such as silicon carbide, or aluma oxides, ceramic powders or blends, can be cast into (e.g., by infiltration casting) a ceramic fiber-based porous ‘preform’ of desired specification using discontinuous alumina-silicate (e.g., Kaowool Saffil Fibers), silicon carbide, ceramic powders, or blends of the preceding. Reinforced or non-reinforced aluminum-based alloys infiltrate the ‘preform’ during the casting procedure, making a MMC with selective reinforcement. Preferably, casting process is performed by a suitable method, including, but not limited to die casting. Alternatively, permanent mold high-vacuum, squeeze casting, lost foam, or centrifugal casting (e.g., U.S. Pat. No. 5,980,792) can be employed.
In particularly preferred embodiments, the cylinder liners 122, 222, 322 and 422 comprise ‘carbon graphite foam’. Preferably, infusion casting is used. For example, an aluminum-based alloys (e.g., eutectic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a ‘preform’ of porous ‘carbon graphite foam’ (with or without particulate reinforcement, such as silicon carbide). Carbon graphite foam (developed at Oak Ridge National Laboratory, USA) has high thermal conductivity and also acts as super-conductor (see, e.g., U.S. Pat. Nos. 6,673,328, 6,663,842, 6,656,443, 6,398,994, 6,387,343 and 6,261,485, all of which are incorporated by reference herein in their entirety). Preferably the silicon carbide volume should be from about 10% to 35% to provide desired friction at wear plate rubbing surface. Infiltration of un-reinforced or reinforced alloy into carbon graphite foam ‘preform’ is during a suitable casting procedure including, but not limited to die casting, high-vacuum permanent mold casting, squeeze casting, or centrifugal casting. According to the present invention, carbon graphite foam can be included in the compositions of at least one of the cylinder liner, and any parts in contact therewith. According to the present invention, the use of carbon graphite foam ‘preforms’ not only substantially reduces manufacturing costs (e.g., relative to the use of ceramic ‘preforms’), but provides an environmentally responsible cylinder liner, because carbon graphite foam is manufactured from a by-product of coal fabrication.
While various embodiments and preferred embodiments of the present invention have been illustrated and described herein, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.
This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 60/542,955 filed 9 Feb. 2004 and entitled FLUID-COOLED CYLINDER LINER, and to U.S. Provisional Patent Application Ser. No. 60/646,239, filed 21 Jan. 2005 of same title, both of which are incorporated by reference herein in their entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4050421 | Cendak | Sep 1977 | A |
| 4172435 | Schumacher | Oct 1979 | A |
| 4662321 | Devaux | May 1987 | A |
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