Patent Application
20180094570
The present disclosure generally relates to internal combustion engines and, more particularly, relates to pistons for internal combustion engines.
Internal combustion engines typically contain one or more pistons. The pistons reciprocate up and down in corresponding and complementarily shaped cylinders present within the internal combustion engines. Such engines are often Otto cycle engines which employ a spark plug or the like for ignition, or Diesel cycle engines which rely on compression ignition. After ignition, (wherein the ignition may occur prior to the top dead center (TDC)) the piston descends within the cylinder in a power stroke before ascending for exhaust and then back down for intake in a repeating sequence.
The pistons of such engines typically include a cylindrical base that has a bottom portion connected to a crank shaft by a connecting rod or the like, and a top portion or piston crown opposite the bottom portion. The piston crown cooperates with the cylinder head to define a combustion chamber. It is within the combustion chamber that the air and fuel are mixed and ignited.
The piston crown is typically bowl-shaped and defined by a circumferential wall that extends from the cylindrical base of the piston. The circumferential wall of the piston may also be known as the piston bowl wall. A fuel injector is typically mounted in the cylinder head and extended into the combustion chamber to communicate fuel to the combustion chamber prior to ignition. Upon ignition, the resulting flame jets flow radially outward and impinge against the piston bowl wall. When the flames collide with the piston bowl wall, a stagnation point is created around the point where jet flames hit the piston bowl wall. Such stagnation points cause the momentum of the jet flames to be reduced.
A problem associated with such phenomena is that the lost momentum of the jet flames detrimentally affects mixing of air and fuel within the piston bowl. In other words, the jet flames within the piston bowl that lose momentum are also not able to reach a region of the piston bowl with a level of oxygen that would allow for a beneficial mixing of air and fuel within the piston bowl. Consequently, a significant amount of unused fuel or slow burning fuel may be present in piston bowls with stagnation points as the jet flames will continuously lose momentum as a result of the collisions. The jet flames will also continuously lose the opportunity to travel to a region of the piston bowl with a higher oxygen level, thereby not allowing for beneficial mixing of air and fuel, and ultimately making for a less efficient, more pollutant forming, engine.
Various engine configurations exist to purportedly improve fuel and air mixing prior to and during combustion. However, such configurations face the common challenge that the piston bowl wall is a fixed structure which continuously obstructs the jet flames and creates stagnation points. In one example, U.S. Pat. No. 4,898,135, discloses an internal combustion engine provided with a reaction chamber within its piston bowl wall to generate radical fuel species during combustion for use during a next succeeding combustion cycle. However, such a system does not have the capacity of allowing the jet flames to avoid collisions with the piston bowl walls. As a result, such systems do not reduce momentum loss of the jet flames within each piston and such systems create stagnation points relative to the piston bowl wall.
In view of the foregoing disadvantages associated with known pistons of internal combustion engines, a need exits for a cost effective solution which would not drastically alter the physical structure of the piston, and yet still allow jet flames travelling within the piston to preserve their momentum. In addition, a need exits for the jet flames to not only preserve their momentum while travelling within the piston bowl, but also be able to travel to an area of the piston bowl with a greater oxygen level to allow for a more beneficial mixing of air and fuel and thus less formation of soot and other pollutants. A still further need also exits for the jet flame to avoid contact with other jet flames. The present disclosure is directed at addressing one or more of the deficiencies and disadvantages set forth above. However, it should be appreciated that the solution of any particular problem is not a limitation on the scope of the disclosure or of the attached claims except to the extent expressly noted.
In one aspect of the present disclosure, an internal combustion engine is provided. The internal combustion engine may include an engine block having a plurality of cylinders therein, a piston reciprocatingly mounted in each cylinder and defining a combustion chamber, with the fuel being ignited in the combustion chamber and generating a plurality of flames. The internal combustion engine may also include a fuel injector communicating fuel to the combustion chamber and a piston crown extending from each piston and defining a piston bowl. The piston bowl has a plurality of stagnation points and mixing zones. The engine also includes a plurality of passageways in the piston crown to guide flames away from stagnation points and to mixing zones.
In another aspect of the present disclosure, a piston is provided. The piston may include a cylindrical base, a circumferential wall extending from the cylindrical base, a piston bowl defined by the cylindrical base and circumferential wall, and a passageway in the circumferential wall adapted to receive a flame and communicate the flame back to the piston bowl wherein the passageway guides the flame to a region with a higher oxygen level.
In yet another aspect of the present disclosure, a method of operating an internal combustion engine is provided. The method may include providing a piston within a cylinder with the piston having a crown with a plurality of flame guiding passageways therein. The piston crown defines a piston bowl and the method may also include injecting fuel into the piston bowl and then igniting the fuel to generate a plurality of flames. The method may also include receiving the flames within each passageway and guiding the flames within the passageways to exit in the piston bowl between other flames travelling within the piston bowl. Oxygen rich zones within the piston bowl may also be regions not configured between the flames.
These and other aspects and features will be more readily understood when reading the following detailed description in conjunction with the accompanying drawings.
While the following detailed description is given with respect to certain illustrative embodiments, it is to be understood that such embodiments are not to be construed as limiting, but rather the present disclosure is entitled to a scope of protection consistent with all embodiments, modifications, alternative constructions, and equivalents thereto.
Referring now to the drawings and with specific reference to
The internal combustion engine 100 also includes a plurality of pistons 200 reciprocating within the plurality of cylinders 114. Each of the pistons 200 is movable to, among other things, increase cylinder pressures to a pressure sufficient to cause ignition of fuel as is well known in Diesel engines. Each piston 200 is coupled to a crankshaft 230 via a connecting rod 233 to cause rotation of the crankshaft 230. The internal combustion engine 100 may also include a fuel source 237. The fuel source 237 may be connected with each of the fuel injectors 116 by a common rail 239 or the like and a plurality of supply passages 246. Other configurations are possible. The internal combustion engine 100 may also comprise one or more sensors 247 to sense values indicative of engine speed or engine load or the like. The internal combustion engine 100 may also include a controller 250 hereinafter referred to as an engine control module (ECM) 250.
In operation, when fuel is injected and ignited, a plurality of distinct jet flames 300 extend radially outward from each injection orifice 121 toward the circumferential wall 262 as shown in the top view of
Turning to
To be clear, however, each piston bowl 264 for each piston 200 may contain more than one stagnation point 350 as there will likely be more than one jet flame 300 travelling within the piston bowl 264 and each jet flame 300 creates its own stagnation point 350 when colliding with the circumferential wall 262. In addition, the entire jet flame 300 travelling within the piston bowl 264 may not generate one of the stagnation points 350. However, whether complete or partial, when the jet flame 300 collides with the circumferential wall 262, a stagnation point 350 is created and the jet flame 300 is less likely to travel to a region within the piston 200 that may have a greater level of oxygen. Further, the collision between the portion or entire jet flame 300 and the circumferential wall 262 causes momentum loss, whereas the inclusion of the flame guiding passageways 370 reduces momentum loss relative to not having the flame-guiding passageways 370.
To allow one or more of the jet flames 300 to preserve their momentum and travel to a region of the piston 200 with greater oxygen, the circumferential wall 262 of the present disclosure is configured with the one or more flame-guiding passageways 370. In doing so, a route away from the stagnation point 350 is provided for at least a portion of each jet flame 300. Further, each piston bowl 264 may contain a number of passageways 370 corresponding to the number of jet flames 300 to thereby enable each jet flame 300 to travel away from each potential stagnation point 350 with reduced momentum loss. More specifically, any portion of the jet flame 300 which enters the passageway 370 without collision maintains its momentum. After the jet flame 300 enters the passageway 370, the passageway 370 guides the jet flame 300 in a path away from the stagnation point 350. A curved path is illustrated in
In the depicted embodiment, when the jet flame 300 has entered the passageway 370, the jet flame may complete a 180° turn away from the stagnation point 350 within the passageway 370. However, the jet flame 300 is not limited to completing a 180° turn within the passageway 370. For example, the jet flame 300 may undergo a variety of angular turns and a number of paths while within the passageway 370. Accordingly, the jet flame 300 is not limited to completing a turn at specific angles while travelling within the passageway 370. Importantly, by avoiding contact with the circumferential wall 262, a portion of the jet flame 300 does not suffer a loss of momentum and thus improves mixing and efficient engine operation.
Referring still to
Turning now to
In actual operation, multiple passageways 370 will likely be provided, and all jet flames 300 that, but for the present invention, may have completely collided with the circumferential wall 262 and generated stagnation points 350, now enter the passageways 370. While unlikely that an entire portion of the jet flames 300 enter the flame-guiding passageways 370, the jet flames 300 thus maintain a greater portion of their momentum by avoiding contact with the circumferential wall 262. Upon exiting the passageways 370 with preserved momentum, they enter mixing zones 382 having greater oxygen levels. As mentioned above, the greater oxygen levels therein enable for a greater mixing of air and fuel and thus more and complete combustion, with less soot emissions.
In general, the present disclosure may find applicability in various industrial applications such as but not limited to internal combustion engines such as Diesel and Otto cycle engine. Such engines may be employed as prime movers, earth movers, rail, marine, and power generation equipment or the like to improve combustion efficiency. The present disclosure does so by improving mixing of air and fuel, and preserving the momentum of jet flames 300 moving through the piston bowl 264. The present disclosure also enables the jet flames 300 to avoid collisions with the circumferential wall 262 and with other jet flames 300. More specifically, the present disclosure provides passageways 370 within pistons 200 that allow the momentum of a plurality of jet flames 300 travelling therethrough to be largely preserved and to travel to mixing zones 382 of the piston 200 with greater oxygen levels. This avoids unnecessary contact with other jet flames 300 within the piston 200 which may have lost more momentum as a result of colliding with the circumferential wall 262 and creating one or more stagnation points 350 within the piston 200. By using passageways 370 within the circumferential wall 262 of the piston 200, the present application provides a simplified and cost effective means of allowing for greater mixing of air and fuel within a piston 200 without compromising the structure of the piston 200.
Turning now to
The method of
Block 606 also exits the jet flames 300 into mixing zones 382 of the piston bowl 264 with a greater oxygen level than the stagnation point 350. Accordingly, the jet flame 300 entering into the mixing zone 382 with a greater oxygen level allows for an increased mixing of air and fuel as a result. The operation of the engine 100 thus is more efficient and produces less soot and other pollutants as well.
The method of
While the preceding text sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of protection is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the scope of protection.
