CROSS-REFERENCE TO RELATED APPLICATION

[001] The current application claims priority under to U.S. provisional patent application serial number 62/081,949, filed on November 19, 2014 and entitled "Insulated Engine," which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

[002] The subject matter described herein relates to systems, methods, and devices for improving the heating of fluids, such as oil, within an engine.

BACKGROUND

[003] The thermal mass of an engine is generally large compared to the heat flux available that can bring the engine up to a desired temperature (e.g., a temperature that improves the viscosity of oil within the engine). Thus, a relatively long delay can occur between engine start-up under cold start conditions and the oil reaching a steady state operating temperature. When the oil is cold (i.e., at cold start), the viscosity of the oil is high, which can result in increased friction within the engine, which can in turn result in decreased efficiency.

SUMMARY

[004] In one aspect, an internal combustion engine includes an inner space of the internal combustion engine configured to at least temporarily contain a fluid, a high thermal mass component having an internal surface disposed adjacent the inner space, and an intervening material disposed on the internal surface of the high thermal mass component. The intervening material prevents direct contact between a bulk of the fluid and the high thermal mass component to limit transfer of heat from the fluid to the high thermal mass component. [005] In another interrelated aspect, a method includes producing heat as a result of operation of an internal combustion engine, transferring at least some of the heat to a fluid in proximity to a plurality of components of the internal combustion engine, and limiting transfer of heat from the fluid to at least one high thermal mass component of the plurality of components. The limiting includes preventing direct contact of the fluid with the at least one high thermal mass component. The preventing of the direct contact results from presence of an intervening material positioned between the fluid and one or more internal surfaces of the at least one high thermal mass component.

[006] In some variations one or more of the following can optionally be included in any feasible combination. The intervening material can include at least one of an insulating material and a low thermal mass material. The low thermal mass material can has a thermal mass that is lower than that of the high thermal mass component. The intervening material can include at least one of include a plastic, a thermo plastic filled with hollow glass microspheres, a ceramic, fiberglass, a refractory material, alumina silica, alumina, a low thermal mass alloy material, and a microporous insulation materials. The intervening material can include a coating applied to internal surfaces of the at least one high thermal mass component. The intervening material can include a barrier component, which can optionally be not completely bonded to the one or more internal surfaces such that a non-circulating amount of the fluid is positioned in a gap between the barrier component and one or more internal surfaces. The one or more internal surfaces can be internal to an inner space of the internal combustion engine in which the fluid resides. The fluid can include exhaust gas, the at least one high thermal mass component can include a metal intake port, and the intervening material can include a coating of an insulating, low thermal mass material. The fluid can include engine inlet air, the at least one high thermal mass component can include a metal intake port, and the intervening material can include a coating on the metal intake port. The coating can extend from an inlet portion of the metal intake port to at least a proximity of a valve seat against which a valve is urged to close the metal intake port. The limiting of the transfer of heat can further include preventing heat losses from the internal combustion engine to an ambient environment by an outer insulation barrier. A heat exchanger can be configured/used to dissipate heat from the fluid after the internal combustion engine has reached a target operating temperature.

[007] The high thermal mass component can include a structural component of the internal combustion engine configured to bear and/or transmit one or more loads associated with operation of the internal combustion engine. A non-load-bearing component can form an additional surface of the inner volume. The non-load-bearing component can be formed of a non-metallic material with insulating and/or low thermal mass properties. The structural component can include at least one of a cylinder and a structural engine lattice, and the non-load- bearing component can include at least one of an oil pan, a crankcase shroud, and an oil retaining part disposed at least partly around the cylinder.

[008] The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

[009] The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations. In the drawings:

[010] FIG. 1 shows a diagram illustrating features of an insulated engine consistent with implementations of the current subject matter; [Oil] FIG. 2 shows an implementation of an engine including structural parts having a variety of thermal mass; and

[012] FIG. 3 shows a process flow chart illustrating features that can be included in a method consistent with implementations of the current subject matter.

DETAILED DESCRIPTION

[013] Oil inside an engine can be heated as it circulates through a part of an engine, such as through bearings, underneath a piston, along other sliding surfaces in the engine, and the like. For example, after oil passes through a bearing or under the piston, it can be thrown against the walls of a crankcase by rotational motion of a crankshaft. The oil can then drain back into a sump (e.g., an oil reservoir) from which it can be recycled. Heat transferred to the oil from combustion of a fuel-air mixture in the cylinder(s) of the engine can be transferred from the moving oil to other parts of the engine, such as engine cases (e.g., the crankcase), thereby heating those other parts of the engine. The amount of heat transferred from the oil to the other parts of the engine in order to warm those parts of the engine to a desired temperature (e.g., a temperature that allows the oil to have a low viscosity) can be relatively high. For example, a first half of the duration of a typical drive cycle of an engine with a 110 cm ^" displacement can be spent warming up oil within the engine. If the oil were heated twice as quickly as in engines using currently available approaches, the fuel efficiency of the whole drive cycle can be improved, possibly by as much as approximately 5% or more based on current calculations. In addition, reductions in heat losses from the engine can advantageously provide more rapid heating of a catalyst for treating exhaust gas constituents as less of the heat generated by fuel combustion is lost to the ambient environment. A catalyst is generally ineffective at converting unburned hydrocarbons, carbon monoxide, and nitrogen oxides to less reactive compounds such as carbon dioxide, water, and nitrogen gas until it reaches a target operating temperature. [014] The present disclosure describes systems, methods, and devices for improving the heating of fluids, such as oil, within an engine. In some implementations, an intervening material (e.g. an insulation layer, a low thermal mass material, a coating, etc. as discussed in more detail below) can be included in the engine that can reduce the heat transfer from the oil to at least some parts of the engine that have a higher thermal mass, such as an engine casing made out of metal. The intervening material can optionally have insulating properties and/or be of a relatively lower thermal mass, for example a thermal mass that is less than the thermal mass of a metal or other material from which the engine part or component is constructed. As such, the intervening material can allow the oil to retain relatively more of the heat transferred to the oil from fuel combustion in the cylinder(s) of the engine rather than allowing this heat to be transferred from the oil to other parts of the engine having the higher thermal mass and/or to the ambient environment.

[015] An intervening material consistent with implementations of the current subject matter can be disposed in one or more of a variety of positions relative to the oil in the engine, such as directly in contact with the oil (e.g., as a coating applied to or otherwise associated with a part of the inside of the engine) or along an outer surface of the engine. In addition, although oil is referred to in various illustrative examples herein, the insulating features of the current subject matter can improve retention of heat by other engine fluids in addition to oil (such as for example water, air, a fuel-air mixture, or the like). Furthermore, although a crankcase is referred to in the described examples, features of the current subject matter can be applied in association with other engine components containing a fluid to which it is desirable to add and within which it is desirable to retain engine heat.

[016] FIG. 1 shows a diagram illustrating an example implementation of an internal combustion engine 100 including an engine component 102, such as, for example a crankcase, having an intervening material that includes an intervening material 104. The intervening material 104 can surround or form a barrier to fluid contact with or circulation near at least a part of an inner space 106 (e.g. a volume containing a fluid) of the engine component 102 in which oil 108 or some other fluid can reside.

[017] The inner insulation layer 104 can have a thermal mass that is lower than that of the engine component 102. The oil 108 can directly contact the inner insulation layer 104 instead of the engine component 102 as the oil 108 flows within (or past, against, etc.) the engine component 102. The presence of the inner insulation layer 104 can reduce the transfer of heat from the oil 108 and can thereby allow the oil 108 to heat faster and more efficiently compared to if the oil 108 were allowed to directly contact the engine component 102. FIG. 1 also shows an optional outer insulation barrier, such as for example outer insulation layer 110, which can optionally be disposed on outer surfaces of the engine component 102 to reduce heat losses from the engine component 102 to the ambient environment 112. It will be understood that some implementations of the current subject matter can include only the inner intervening material 104, while others can include both the inner intervening material 104 and an outer insulation layer 110, or even only the outer insulation layer 110. The retention of heat in the oil by action of the inner insulation layer 104 and/or the outer insulation barrier can allow the oil 108 to be more rapidly and more efficiently heated to a temperature that lowers its viscosity and reduces friction within the engine 100, among possible advantages of the current subject matter.

[018] Consistent with implementations of the current subject matter, the inner insulation layer 104 can be configured and positioned in a variety of ways to realize one or more advantages. In one example, the inner insulation layer 104 can be positioned between the engine component 102 and the oil 108, such as along an inner wall of the engine component 102 (e.g. a crankcase or other engine structure that contains oil or some other fluid). The intervening material 104 can include a coating along an inner wall of the engine component 102. One example approach for creating the inner insulation layer 104 that includes a coating can include coating a casting surface used to form the engine component 102 before machining. Alternatively or in addition, the inner insulation layer 104 can include one or more inserts that are molded and assembled into the engine 100 during assembly of the engine. An insulating coating can optionally be applied to certain engine components either before or after assembly of the engine, for example by a spray process, a dipping or immersion process, or the like.

[019] In addition, insulation layer castings and other engine parts can be designed so that as the engine is assembled, insulation layers can become trapped within the engine and positioned to reduce (or optionally eliminate) oil contact with engine components having a greater thermal mass than the insulation layers. In some implementations, bonding between the intervening material 104 and an associated engine component 102 (e.g. a crankcase or the like) is not required. As such, the intervening material 104 can be either bonded directly against the crankcase 102 (e.g. as a coating or the like) or positioned a distance away from an inner (e.g. oil contacting) surface of the engine component 102 (e.g. as a barrier component). In one example, a gap or cavity can be formed between an internal surface of the engine component 102 and a barrier component of the intervening material 104. Oil 108 (or some other fluid) can be allowed to enter the gap or cavity between the engine component 102 and the barrier component. Oil itself can serve as an insulating layer, such as for example oil that is trapped in a relatively narrow cavity where it is unable to efficiently circulate (and thereby unable to provide convective heat transfer). In this manner, an intervening material 104 that is not perfectly bonded or otherwise sealed to an internal surface of an engine component 102 can include additional insulating features due to oil that becomes trapped in any gaps resulting between the intervening material 104 and the internal surface of the engine component 102.

[020] As noted above, in some implementations an outer insulation layer 110 can be positioned along an outer part of an engine component 102, such as along an outer wall of the crankcase (not shown). Placement of the outer insulation layer 110 along an outer surface of the engine can improve the time and energy required to bring either the oil 108 or the engine itself up to a desired temperature (e.g., where the oil has a lower viscosity) compared to a conventional engine (e.g. one having no insulation layers), for example due to reduced heat losses to the ambient environment 112. Use of an intervening material 104 along or within an internal surface of an engine component 102 can be advantageous in speeding and improving the efficiency of heating of the oil 108 compared to only an outer insulation layer 110 positioned along an outer surface of the engine component 102. The intervening material 104 can reduce heat transfer to the thermal mass of the engine component 102 and to the ambient environment 112. As noted above, both an intervening material 104 and an outer insulation layer 110 can be used in various implementations of the current subject matter.

[021] An intervening material 104 and/or an outer insulation layer 110 consistent with implementations of the current subject matter can be made out of a variety of materials, such as one or more materials having a thermal mass that is less than metal. For example, either the outer insulation later 110 or the inner insulation layer 104 can include plastics, thermo plastics filled with hollow glass microspheres, ceramics, fiberglass, refractory materials, alumina silica, alumina, low thermal mass alloy materials, microporous insulation materials, and the like.

[022] In another implementation of an insulated engine 100, at least a part of an engine block can be made out of non-metal materials or materials having a lower thermal mass than metal, including any of the outer or inner insulation layer materials disclosed herein. For example, one or more of a variety of materials having a relatively lower thermal mass, such as for example ceramics, carbon fiber, plastics, etc., can be used to form one or more oil-containing surfaces or walls within an engine structure. Engine components constructed from such low thermal mass materials can allow oil that comes in contact with these engine components to lose relatively less heat and therefore more rapidly and efficiently reach a desired temperature (e.g. a temperature at which the viscosity of the oil is within an acceptable operating range for reducing engine friction).

[023] An engine structure consistent with implementations of the current subject matter can include a lattice of interconnected structural parts, which can generally be formed of metal or some other high thermal mass material, that bear and/or transmit the loads (torsional, compressive, expansive, etc.) associated with engine operation. Such an engine structure can also include non-metallic, or otherwise low thermal mass materials used in non-load bearing components that form at least one internal surface of the inner volume (e.g. that contain the fluid). For example, walls of the engine that contain the oil inside and keep the air and dirt outside can be made of low thermal mass materials (e.g., any of the outer or inner insulation layer materials disclosed herein). In some implementations, a cylinder block can include a metal cylinder having a nylon (or other insulating or low thermal mass material) molding disposed at least partially around it (i.e., an insulation layer) to form an oil retaining part including a cooling jacket and a connection down to an oil pan. Main load bearing structural elements can be cast with the cylinder and an insulation layer (e.g., including nylon) can be molded onto such parts in a secondary operation. Cylinder head bolts can also attach to the metal cylinder as well.

[024] In some implementations, once the oil 108 has reached a desired temperature or temperate range, the temperature of the oil 108 can be maintained at the desired temperature or within the desired temperature range. For example, once at the desired temperature or within the desired temperature range, the oil 108 can be circulated through an external cooler (not shown) that can either maintain or reduce a temperature of the oil. The external cooler can have a large heat transfer surface area for efficient cooling.

[025] An additional optional advantage of the system and methods described herein can include readily controllable center-to-center distances for an opposed piston engine while using reduced weight materials for those engine components that are not structural. For example, an entire engine made out of an iron casting can be too heavy for a light vehicle application. However, an iron or steel connection between crankshafts can allow the lash on the crank connection gears to remain constant over the changes in operating temperature, such as when the gears are also made of iron. Other engine components that do not bear structural loads can be formed of lighter weight, lower thermal mass materials. In a typical opposed piston engine formed entirely of metal, aluminum can be used for the engine block to save weight. However, aluminum has a different thermal expansion coefficient than cast iron, so as the engine block expands with heating, the spacing between cast iron or steel gears mounted to the engine body can change, thereby causing gear lash, which can lead to increased noise, vibration, or even wear. Use of a cast-iron structural engine lattice with lighter weight, non-structural oil-retaining parts can save weight while minimizing thermal expansion effects on the gear train of the engine.

[026] For example, as shown in FIG. 2, an implementation of an engine 300 can include structural parts 302 constructed of one or more first materials having a first, relatively higher, thermal mass and sufficient structural strength, rigidity, durability, etc. to allow the structural parts to retain their shapes and relative positions under engine operation loads (e.g. compression, expansion, rotational, torsional, etc. loads typically experienced during operation of the engine 300. For example, these structural parts 302 can be constructed, formed, etc. of iron, steel, aluminum, etc. Other, non-structural parts 304 of the engine 300 can be constructed or otherwise formed of a one or more second materials having a second, relatively lower, thermal mass. The second materials need not have as high a structural strength, rigidity, durability, etc. as the structural parts 302. The non-structural parts 304 can include parts that surround a portion of the interior of the engine 300 (e.g. an oil pan, a crankcase shroud, etc.). Additional active components 306 of the engine 300 can also be made out of various materials, which can optionally have range of thermal mass. [027] FIG. 3 shows a process flow chart 300 illustrating features of a method consistent with implementations of the current subject matter. Some or all of the listed features can be included in an implementation. At 302, an engine fluid is heated, for example as a result of heat produced due to operation of an engine (e.g., due to combustion of fuel-air mixtures in one or more cylinders or other combustion chambers of the engine). Heat transfer from the fluid to an engine component is limited at 304, for example due to the engine component being formed of or coated with a material having a lower thermal mass and greater insulating properties than structural (e.g., load-bearing) components of the engine. At 306, heat can optionally be transferred from the engine fluid through one or more heat exchangers (e.g., to transfer heat to the ambient environment) to maintain the engine fluid within a target operating temperature range.

[028] Consistent with implementations of the current subject matter, insulating coatings can be applied to engine components, or engine components can be formed out of insulating material, for a variety of reasons, including but not limited to those discussed above. For example, it can be advantageous to insulate intake air from the metal of the intake port. Volumetric efficiency of the engine can be increased if heating of the inlet air is reduced or otherwise limited. Heating of the intake air can decrease the volumetric concentration of oxygen molecules (e.g., per the ideal gas law). In some implementations of the current subject matter, some or all of the intake port can be formed of an insulating, low thermal mass material, such as for example plastic. In other variations, a metal intake port can be coated with plastic or some other low thermal mass or insulating material. The insulating material can optionally extend from the inlet portion of the intake port to at least the proximity of a valve seat against which a valve (e.g. a poppet valve or a sleeve valve) is urged to close the intake port. In some examples, a process for applying the low thermal mass, insulating coating to other parts of an engine can concurrently (or as part of the same process) be applied to coat the intake port. If a dipping, immersion, spray, or other similar process is used in applying the coating, certain engine components such as cooling jackets or the exhaust port, which are exposed to higher temperatures that might damage such a coating, can be protected during application of the coating so that they are not coated. Additionally, since the shape of the intake port can have a relatively large impact on engine performance, it can be desirable to apply the insulation to the forms that make up the internal shapes in the casting process. Among other options, the casting form can be sprayed with a ceramic / aluminum mix or dipped in ceramic slurry that contains some metallic particles. Once coated, the form can be inserted into the mold and molten aluminum pored around it. During this process, the molten aluminum can bond to the ceramic so that when the form is removed, the insulator remains structurally attached to the casting.

[029] Approaches consistent with implementations of the current subject matter can be applied in the exhaust port as well. For example, the fluid whose heat transfer is limited can be exhaust gas, and the high thermal mass component can be or include a metal exhaust port. The intervening material can includes a coating on internal surfaces (e.g. in contact with the exhaust gases) of the metal exhaust port. By limiting the heat transfer to the metal exhaust port walls, the exhaust gases remain at a higher temperature, which can be advantageous in enabling faster heating of the catalyst for early catalyst light off.

[030] In the descriptions above and in the claims, phrases such as "at least one of or "one or more of may occur followed by a conjunctive list of elements or features. The term "and/or" may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases "at least one of A and Β;" "one or more of A and Β;" and "A and/or B" are each intended to mean "A alone, B alone, or A and B together." A similar interpretation is also intended for lists including three or more items. For example, the phrases "at least one of A, B, and C;" "one or more of A, B, and C;" and "A, B, and/or C" are each intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together." Use of the term "based on," above and in the claims is intended to mean, "based at least in part on," such that an unrecited feature or element is also permissible.

[031] The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail herein, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and sub-combinations of the disclosed features and/or combinations and sub-combinations of one or more features further to those disclosed herein. In addition, the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. The scope of the following claims may include other implementations or embodiments.