Device and method for managing self-ignition in injector and combustion chamber in cylinder

Abstract

An apparatus for managing ignition in a chamber of an in-cylinder injector that introduces fuel directly into a combustion chamber of an internal combustion engine. The chamber includes an injection hole in fluid communication with the combustion chamber. A controller connected to the in-cylinder injector is programmed to: actuate the in-cylinder injector to inject fuel; determining whether self-ignition is possible in the chamber according to the operating parameters; and when self-ignition is possible, performing a mitigation strategy to prevent self-ignition within the chamber.

Description

Technical Field

[0001] The present application relates to a device and method for managing the self-ignition state in the cylinder injector and combustion chamber of an internal combustion engine, and more specifically, to a device and method for reducing and preferably preventing the possibility of self-ignition in the cylinder injector and selectively increasing the possibility of self-ignition in the combustion chamber. Background Art

[0002] The following discussion of the background of the invention is intended only to facilitate understanding of the invention. It should be understood that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge of a person skilled in the art in any jurisdiction at the priority date of the present invention.

[0003] Late cycle injection of gaseous fuel directly into the combustion chamber of an internal combustion engine, where the fuel burns in a diffusion combustion mode (also known as a diesel cycle engine), provides multiple benefits over premixed gaseous fuel engines, including high thermal efficiency, combustion stability, and knock-free operation. As used herein, a gaseous fuel is any fuel that is in a gaseous state under standard temperature and standard pressure conditions, where standard temperature is a temperature of zero degrees Celsius (0°C) and standard pressure is an absolute pressure of 1 bar. An in-cylinder injector is used to inject the gaseous fuel directly into the corresponding combustion chamber because, in a late cycle engine, the gaseous fuel is injected after the intake valve is closed. The nozzle of the in-cylinder injector extends into the combustion chamber and is therefore exposed to the elevated temperatures that exist during combustion of the gaseous fuel.

[0004] The thermal efficiency of an internal combustion engine can be improved by increasing the compression ratio. The compression ratio is defined as the ratio between the volume of the combustion chamber at its maximum volume (specifically at the point where the intake valve is closed during or after the intake stroke) and its minimum volume (specifically at top dead center at the end of the compression stroke). As the compression ratio increases, both the temperature and pressure in the combustion chamber at the end of the compression stroke increase, and, all other conditions remaining the same, the peak combustion temperature and peak cylinder pressure (PCP) will also increase.

[0005] For a diesel cycle engine operating at a high compression ratio, the temperature and pressure environment inside the capsule of an in-cylinder injector may be such that any residual fuel and charge mixture in the capsule may reach autoignition conditions before normal injection begins. The capsule is a chamber within the in-cylinder injector between the injection valve and one or more injection holes in the nozzle. Combustion of residual fuel within the capsule may produce a rapid increase in pressure and temperature within the capsule volume, which may result in increased stress and wear on the nozzle of the in-cylinder injector, thereby potentially shortening the useful life of the injector.

[0006] The type of fuel also affects the thermal load on the in-cylinder injector. For example, due to the high flame speed of hydrogen, the flame lift distance of a hydrogen jet emanating from the injection hole of the nozzle is shorter than the flame lift distance of a natural gas jet or a diesel spray. In this regard, the thermal load on the in-cylinder injector tip, especially around the injection hole, is significantly higher than that of natural gas or diesel. The high thermal load may lead to a reduction in the strength of the metal, which contributes to a shortened injector service life.

[0007] The prior art lacks techniques for thermal management of nozzles for in-cylinder injectors, particularly for those operating in high compression ratio environments and / or injecting fuels with high flame speeds. The present apparatus and method provide techniques for thermal management of nozzles for in-cylinder injectors, particularly for managing auto-ignition conditions in the chamber and combustion chamber of an in-cylinder injector of an internal combustion engine. Summary of the invention

[0008] An improved apparatus for managing ignition in a chamber within an in-cylinder injector that introduces fuel directly into a combustion chamber of an internal combustion engine. The chamber may include at least one injection hole and may be in fluid communication with the combustion chamber through the at least one injection hole. The apparatus includes a controller operably connected to the in-cylinder injector and programmed to: selectively actuate the in-cylinder injector to inject fuel directly into the combustion chamber; determine whether auto-ignition is likely in the chamber based on engine operating parameters; and when auto-ignition is likely, execute a mitigation strategy to prevent auto-ignition in the chamber of the in-cylinder injector.

[0009] The controller may also be programmed to use a standard engine control parameter map when auto-ignition is not possible and to use a modified engine control parameter map when auto-ignition is possible. The engine operating parameters may be one or more of a geometric compression ratio, an effective compression ratio, a fuel type, a fuel composition, an intake charge temperature, an inlet manifold pressure, an inlet manifold temperature, an exhaust gas recirculation concentration, an engine speed, and an engine load. The fuel may be hydrogen, natural gas, a mixture of hydrogen and natural gas, or a mixture of hydrogen and other gaseous fuels.

[0010] When executing the mitigation strategy, the controller can be programmed to: determine a critical crank angle during the compression stroke when self-ignition in the chamber becomes possible; determine a mitigation amount of fuel that needs to be injected before the critical crank angle to prevent self-ignition in the chamber; and actuate the in-cylinder injector to perform a mitigation injection of the mitigation amount of fuel before the piston traveling in the combustion chamber reaches the critical crank angle during the compression stroke. The mitigation amount of fuel reduces the possibility of self-ignition in the chamber and preferably prevents self-ignition in the chamber at least before the main injection of fuel occurs later during the compression stroke. Alternatively or additionally, when executing the mitigation strategy, the controller can be programmed to: determine a critical compression ratio that produces a pressure and temperature environment in the chamber suitable for self-ignition; and adjust the effective compression ratio so that the effective compression ratio is less than the critical compression ratio. The critical compression ratio may be calculated as a function of at least one engine operating parameter selected from the group consisting of fuel type, fuel composition, intake charge temperature, inlet manifold pressure, inlet manifold temperature, exhaust gas recirculation concentration, engine speed, and engine load. Alternatively or additionally, when executing the mitigation strategy, the controller may be programmed to increase coolant flow through the charge air cooler to reduce the inlet manifold temperature or the intake charge temperature at the beginning of the compression stroke.

[0011] The controller may also be programmed to execute a second mitigation strategy when auto-ignition of the fuel in the combustion chamber is not possible. When executing the second mitigation strategy, the controller may be programmed to: determine a critical compression ratio that produces a pressure and temperature environment in the combustion chamber suitable for auto-ignition; and adjust the effective compression ratio so that the effective compression ratio is greater than or equal to the critical compression ratio. Alternatively or additionally, when executing the second mitigation strategy, the controller may be programmed to reduce coolant flow through the charge air cooler to increase the inlet manifold temperature or the intake charge temperature at the beginning of the compression stroke.

[0012] An improved method for managing ignition in a chamber within an in-cylinder injector that introduces fuel directly into a combustion chamber of an internal combustion engine. The chamber may include at least one injection hole and may be in fluid communication with the combustion chamber through the at least one injection hole. The method includes: determining whether auto-ignition is likely in the chamber based on engine operating parameters; and when auto-ignition is likely, executing a mitigation strategy to reduce the likelihood of auto-ignition in the chamber of the in-cylinder injector and preferably prevent auto-ignition in the chamber of the in-cylinder injector. When auto-ignition is not likely, a standard engine control parameter map may be used, and when auto-ignition is likely, a modified engine control parameter map may be used. The engine operating parameters may be one or more of a geometric compression ratio, an effective compression ratio, a fuel type, a fuel composition, an intake charge temperature, an inlet manifold pressure, an inlet manifold temperature, an exhaust gas recirculation concentration, an engine speed, and an engine load.

[0013] The mitigation strategy may include: determining a critical crank angle during the compression stroke when self-ignition in the chamber becomes possible; determining a mitigation amount of fuel that needs to be injected before the critical crank angle to prevent self-ignition in the chamber; and performing a mitigation injection of the mitigation amount of fuel before the piston traveling in the combustion chamber reaches the critical crank angle during the compression stroke. The mitigation amount of fuel reduces the possibility of self-ignition in the chamber and preferably prevents self-ignition in the chamber at least before the main injection of fuel occurs later during the compression stroke. Alternatively or in addition, the mitigation strategy may include: determining a critical compression ratio that produces a pressure and temperature environment suitable for self-ignition in the chamber; and adjusting the effective compression ratio so that the effective compression ratio is less than the critical compression ratio. The critical compression ratio can be calculated as a function of at least one engine operating parameter, the engine operating parameter selected from the group consisting of fuel type, fuel composition, intake charge temperature, inlet manifold pressure, inlet manifold temperature, exhaust gas recirculation concentration, engine speed and engine load. Alternatively or additionally, mitigation strategies may include increasing coolant flow through the charge air cooler to reduce inlet manifold temperature or intake charge temperature at the start of the compression stroke.

[0014] In the method, a second mitigation strategy may be implemented when auto-ignition of the fuel in the combustion chamber is not possible. The second mitigation strategy may include: determining a critical compression ratio that produces a pressure and temperature environment in the combustion chamber suitable for auto-ignition; and adjusting the effective compression ratio so that the effective compression ratio is greater than or equal to the critical compression ratio. Alternatively or additionally, the second mitigation strategy may include reducing coolant flow through a charge air cooler to increase an inlet manifold temperature or an intake charge temperature at the beginning of a compression stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate specific embodiments of the devices, systems and methods and, together with the above general description and detailed description of the specific embodiments, serve to explain the principles of the devices, systems and methods.

[0016] Figure 1 is a cross-sectional view of a combustion chamber of an internal combustion engine according to an embodiment.

[0017] Figure 2 is Figure 1 A partial cross-sectional view of a prior art nozzle for an in-cylinder injector used in an internal combustion engine.

[0018] Figure 3 is a cross-sectional view of a combustion chamber of an internal combustion engine according to another embodiment.

[0019] Figure 4 is Figure 3A partial cross-sectional view of a prior art nozzle for an in-cylinder injector used in an internal combustion engine.

[0020] Figure 5 is a graphical view showing that for fuel-air equivalence ratios of 0.5, 1.0, 1.5, and 2.0, Figure 1 and Figure 3 The 500 microsecond delay limit of the main fuel used in the internal combustion engine is shown, and the pressure state and temperature state at the end of compression are shown for normalized compression ratios of 1.0, 0.913, 0.826 and 0.739, wherein for each normalized compression ratio, a common compression start temperature and a compression start pressure range between 0.5 and 3.0 bar are used.

[0021] Figure 6 It is used to ease Figure 2 and Figure 4 Flow chart of the algorithm for self-ignition in the primary pocket of an in-cylinder injector.

[0022] Figure 7 is used for Figure 6 A flowchart of the algorithm of the mitigation strategy of the algorithm, which mitigation strategy adopts mitigation injection.

[0023] Figure 8 is for Figure 1 of internal combustion engines Figure 7 A graphical view of the injection flows for the mitigation injection, pilot injection, and main injection used in the algorithm.

[0024] Fig. 9 is for Figure 3 Internal combustion engine Figure 7 A graphical view of the injection flow rates of the mitigation injection and the main injection used in the algorithm.

[0025] Fig.10 is used for Figure 6 Flowchart of an algorithm for a mitigation strategy employing a change in the effective compression ratio.

[0026] Fig.11 is used for Figure 6 Flowchart of the algorithm for the mitigation strategy of the algorithm which employs changes in inlet manifold temperature.

[0027] Fig.12 are used to prevent Figure 2 and Figure 4 Self-ignition in the main chamber of the in-cylinder injector and enhanced Figure 1 and Figure 3 Flow chart of an algorithm of auto-ignition in a combustion chamber of an internal combustion engine.

[0028] Fig.13 is used for Fig.12 Flowchart of an algorithm for a self-ignition enhancement mitigation strategy employing a change in the effective compression ratio.

[0029] Fig.14 is used for Fig.12 Flowchart of an algorithm for an auto-ignition enhancement mitigation strategy that employs changes in inlet manifold temperature.

[0030] Fig.15 Is used to determine whether to operate in single fuel auto-ignition mode or forced ignition mode Figure 1 and Figure 3 Flowchart of the algorithm of an internal combustion engine. DETAILED DESCRIPTION

[0031] refer to Figure 1, an internal combustion engine 10 is shown in simplified form to facilitate understanding of the present technology. In the illustrated embodiment, the engine 10 is shown as having one cylinder, in other embodiments, there may be more than one cylinder. A combustion chamber 20 is formed by a cylinder wall 30, a cylinder head 40, and a piston 50. The piston 50 reciprocates within a cylinder 60, whereby a piston rod 70 connects the piston 50 to a crankshaft (not shown) and converts the reciprocating motion of the piston 50 into a circular motion of the crankshaft. The cylinder wall 30 forms a bore in an engine block 80, which may be any size (diameter) suitable for an internal combustion engine. For example, in light-duty engine applications, the bore diameter is typically less than 100 mm, in medium-duty and heavy-duty engine applications, the bore diameter may be in the range of 100 mm to 180 mm, and in high horsepower engine applications, the bore diameter is greater than 180 mm. Generally, as the bore diameter increases, the maximum engine speed decreases, primarily due to the increase in the momentum of the piston, which is accompanied by an increase in the mass and velocity of the piston, thereby exerting increased stress on engine components, as known to those skilled in the art. The piston 50 includes a piston bowl 90 in its top portion facing the cylinder head 40. The air handling system includes an intake port 100 and an intake valve 110 configured to cooperate with the cylinder 60, the cylinder head 40 and the piston 50 to allow intake air to enter the combustion chamber 20 and establish a main body movement of the intake charge therein. The main body movement of the intake charge (also referred to as the main charge movement) can be a swirl motion of the intake charge rotating around the longitudinal axis 120, a tumble motion of the intake charge rotating around an axis orthogonal to the longitudinal axis 120, or a combination of swirl motion and tumble motion. For a diesel cycle engine, the main charge motion is usually a swirl, because a diesel cycle engine generally has a flat cylinder head and piston bowl shape that does not support tumble motion. Alternatively, a static combustion chamber can be established, where a static combustion chamber refers herein to a combustion chamber in which there is negligible swirl or tumble of the intake charge, preferably no swirl or tumble of the intake charge. The air handling system also includes an exhaust port 130 and an exhaust valve 140, and as known to those skilled in the art, may include other components common in air handling systems that are not shown in the figure, such as: a turbocharger including a turbine in fluid communication with the exhaust gas for driving a compressor to selectively compress the intake air; a charge air cooler for cooling the intake air compressed by the turbine; and an aftertreatment system for reducing pollutants coming out of the tail pipe. The intake valve 110 and the exhaust valve 140 may be actuated in various ways, such as by a cam driven by the engine 10, or may be electronically actuated by an electronic controller 150. In some embodiments, the intake valve 110 and the exhaust valve 140 are actuated by a variable valve timing (VVT) system or a variable valve actuation (VVA) system (neither of which is shown), whereby the timing of the opening and closing of the valves 110 and 140 may be adjusted.At the top dead center (TDC) position, there is a small gap (not shown) between the top land surface 160 of the piston 50 and the flame stop 170. In this position of some embodiments, valves 110 and 140 can align with recessed portions (not shown) in the piston 50 so that the valves can be in an open position without interfering with the piston.

[0032] In-cylinder injector 180 is shown mounted in cylinder head 40 and introduces the main fuel directly into combustion chamber 20. As used herein, the main fuel may be hydrogen, natural gas, a mixture of hydrogen and natural gas, or a mixture of hydrogen and other gaseous fuels. Although in-cylinder injector 180 is shown as being centrally mounted, in other embodiments, it is possible that the injector may be mounted offset from the longitudinal axis 120 of cylinder 60, or mounted through cylinder wall 30 instead of cylinder head 40. That is, this particular location of the fuel injector is not necessary for the disclosed arrangement, and the mounting location may be determined by the specific structure and available space of the engine. In the illustrated embodiment, in-cylinder injector 180 also introduces a pilot fuel, such as diesel, into combustion chamber 20, which is compressibly ignitable due to the temperature and pressure generated during the compression stroke of piston 50. The pilot fuel serves as a high energy ignition source to ignite the main fuel and is a type of forced ignition. Main fuel is supplied from main fuel supply 12 to in-cylinder injector 180 via conduit 16, and pilot fuel is supplied from pilot fuel supply 14 to in-cylinder injector 180 via conduit 18. In the illustrated embodiment, in-cylinder injector 180 is a concentric needle fuel injector that can introduce pilot fuel separately and independently from the main fuel. In alternative embodiments, in-cylinder injector 180 can include a body having side-by-side main fuel injection assemblies and pilot fuel injection assemblies, or separate fuel injectors can be used to introduce main fuel and pilot fuel directly into combustion chamber 20. Controller 150 is operably connected to in-cylinder injector 180 to actuate the in-cylinder injector via connection 152 to introduce main fuel directly into combustion chamber 20, and to actuate the in-cylinder injector via connection 154 to introduce pilot fuel directly into combustion chamber 20. In-cylinder injector 180 is actuatable to introduce pilot fuel independently and separately from the main fuel, and the injection timing of the pilot fuel and the main fuel is determined based on the engine operating state and may or may not overlap. In other embodiments, the main fuel may be ignited by another type of forced ignition rather than by the pilot fuel, such as a spark plug, glow plug or other heating surface, microwave ignition device, and laser igniter. When the fuel is ignited by forced ignition, the ignition source is also referred to as a forced ignition source. The pilot fuel typically contains significantly more energy and is distributed to various locations in the combustion chamber by injection. In contrast, a spark plug or glow plug is a low-energy, single-point ignition source.

[0033] Reference now Figure 2 , in-cylinder injector 180 is described in more detail. Injection nozzle 190 extends into combustion chamber 20, and injection nozzle 190 includes a main injection hole 200 for introducing main fuel and a pilot injection hole 210 for introducing pilot fuel through a concentric needle arrangement. Figure 2Only the nozzle 190 of the in-cylinder injector 180 is shown, and a more detailed description of similar dual fuel injectors can be found in the applicant's U.S. Patents 10,294,908 issued on May 21, 2019 and 10,502,169 issued on December 10, 2019, both of which are incorporated herein by reference. The valve body 220, which may include one or more components, encapsulates the fuel injector 180, and the valve body 220 includes known structures for accommodating corresponding actuator assemblies for the main valve member 230 and the pilot valve member 240, inlets for receiving the main fuel and the pilot fuel, and conduits for delivering the main fuel and the pilot fuel to the nozzle portion of the valve body 220 shown. The main valve member 230, also known as a hollow needle or hollow barrel, is actuatable to reciprocate within the valve body 220. Main valve member 230 is reciprocated to open and close main injection valve 250, wherein in the closed position, main valve member 230 abuts main valve seat 260, and in the open position, main valve member 230 is spaced apart from main valve seat 260. When main injection valve 250 is opened, main fuel stored in pressurizing chamber 270 flows through main injection valve into main bag 280a, and is introduced into combustion chamber 20 through main injection hole 200 formed in valve body 220. Main bag 280a is a chamber in in-cylinder injector 180, located downstream of main injection valve 250, and is in fluid communication with combustion chamber 20 through at least one main injection hole 200. Although in Figure 2 Only one main injection hole 200 is shown in the cross section shown, but it will be understood by those skilled in the art that there are typically multiple main injection holes, such as spaced around the periphery of the nozzle 190. In the illustrated in-cylinder injector 180, the boost chamber 270 and the main pocket 280a are annular cavities formed between the valve body 220 and the main valve member 230. The pilot valve member 240, also referred to as a needle, is actuatable to reciprocate within the hollow interior of the main valve member 230. The pilot valve member 240 is reciprocated to open and close the pilot injection valve 290, wherein in the closed position, the pilot valve member 240 abuts the pilot valve seat 300, and in the open position, the pilot valve member 240 is spaced from the pilot valve seat 300. When the pilot injection valve 290 is opened, the pilot fuel stored in the plenum chamber 310 flows through the pilot injection valve into the pilot bladder 320 and is introduced into the combustion chamber 20 through the pilot injection hole 210 formed in the tip wall 330, which in the illustrated embodiment is part of the main valve member 230. Figure 2Only one pilot injection hole 210 is shown in the cross section shown, but it will be understood by those skilled in the art that there are typically multiple pilot injection holes, spaced, for example, around the perimeter. In the illustrated in-cylinder injector 180, the boost chamber 310 is an annular cavity formed between the main valve member 230 and the pilot valve member 240, and the pilot pocket 320 is a chamber defined by the main valve member 230 and the pilot valve member 240 and located downstream of the pilot injection valve 290. In an exemplary embodiment, the main valve member 230 and the pilot valve member 240 of the in-cylinder injector 180 are each hydraulically actuated, and the pilot fuel performs a dual function as a hydraulic fluid. In an alternative embodiment, the main valve member 230 and the pilot valve member 240 may also be electrically actuated and may be directly moved by magnetic force.

[0034] Reference now Figure 3 , an internal combustion engine 11 according to another embodiment is shown in simplified form, wherein components identical to the previous and all other embodiments are given the same reference numerals and may not be described in detail again, generally only the differences are discussed. In-cylinder injector 181 is a single fuel injector that introduces only main fuel directly into combustion chamber 20. Reference Figure 4 , showing in more detail nozzle 191 of in-cylinder injector 181. In the illustrated embodiment, main valve member 231 is a needle, and although main valve member 231 may be a hollow needle main valve member 230 in in-cylinder injector 180, this need not be done because there is no pilot valve member in in-cylinder injector 181 that is concentrically aligned with main valve member 231. Figure 4 The main capsule 280b is not like Figure 2 Although the two chambers are of different geometric shapes, for ease of reference, they are referred to herein as the main bladder 280a.

[0035] Under some conditions, any main fuel present in main pocket 280a and main injection hole 200 in in-cylinder injector 180 or in main pocket 280b and main injection hole 200 in in-cylinder injector 181 may be ignited prior to main fuel injection, which may produce a rapid increase in pressure and temperature inside nozzles 190 and 191, respectively, and result in increased stress and wear on the nozzles, which in a worst case may result in failure of in-cylinder injectors 180 and 181. As used herein, chamber 285 refers to main pocket 280a and main injection hole 200 in in-cylinder injector 180 and main pocket 280b and main injection hole 200 in in-cylinder injector 181. A computational fluid dynamics model of engine 10 was established and evaluated to determine the concentration of remaining main fuel (e.g., hydrogen) within chamber 285. As the piston 50 moves upward toward TDC, it is determined that any residual main fuel remaining in the chamber 285 at the beginning of the compression stroke diffuses from the chamber 285 into the combustion chamber 20, such that the fuel-air mixture within the chamber 285 becomes too lean to ignite during the pre-ignition window in the compression stroke, when conditions are favorable for auto-ignition. As used herein, the pre-ignition window associated with the chamber 285 is a period of time during the compression stroke (defined by a starting crank angle and an ending crank angle) during which the pressure and temperature environment within the chamber 285 can maintain the ignitable mixture at the auto-ignition temperature for a period of time equal to or longer than the ignition delay associated with the main fuel. The pre-ignition window can extend into the expansion stroke, where the pressure and temperature conditions at the end of compression begin to drop during the expansion stroke in the absence of combustion, such that favorable auto-ignition conditions can exist for a brief period of time at the beginning of the expansion stroke. This allows for an understanding that the source of the main fuel within the chamber 285 is not primarily residual fuel from a previous combustion cycle. It is noteworthy that the source of the main fuel in the chamber 285 that causes self-ignition before fuel injection is determined to be the main fuel leaking through the main injection valve 250, which has a sufficient leakage flow to produce a mixture that can be ignited in the chamber 285 during the pre-ignition window. For conventional gaseous fuels used in late-cycle direct-injection diesel cycle engines, such as natural gas, when the injection valve 250 is closed, the leakage flow through the injection valve 250 is below the level required to produce an ignitable mixture in the chamber 285. However, when using a gaseous fuel such as hydrogen, it is more difficult to seal hydrogen under high pressure conditions because the size of the hydrogen diatomic molecule (H2) is significantly smaller than that of the methane molecule (CH4), where methane is the most abundant component in natural gas. Therefore, when the injection valve 250 is closed, the leakage flow of hydrogen through the injection valve 250 is more likely to exceed the level that prevents the formation of an ignitable mixture in the chamber 285, which can be ignited during the pre-ignition window. It is noteworthy that the ignitable mixture in the chamber 285 includes fuel and an oxidant, such as oxygen.

[0036] The main factors that determine whether auto-ignition occurs in chamber 285 are compression ratio, intake charge temperature (ICT) and intake charge pressure (ICP) at the beginning of the compression stroke, and fuel type or fuel composition. ICT and compression ratio together determine the compression end temperature, ICP and compression ratio together determine the compression end pressure, and the temperature and pressure conditions of the entire compression stroke determine whether there is a self-ignition condition. A higher compression ratio results in a higher compression end temperature and compression end pressure, which increases the heat load on the nozzles 190 and 191, thereby raising the temperature and pressure conditions in chamber 285. The compression ratio can be a geometric compression ratio or an effective compression ratio. The geometric compression ratio is the maximum compression ratio that can be achieved in a specific internal combustion engine, and is defined as the ratio between the maximum volume of the combustion chamber 20 when the piston 50 is at or near the bottom dead center when the intake valve is closed (during the intake stroke or compression stroke) and the volume of the combustion chamber 20 when the piston 50 is at the top dead center. The effective compression ratio is less than or equal to the geometric compression ratio, which can be achieved by adjusting the intake valve closing timing using VVT or VVA, and can be defined as the ratio between the volume of the combustion chamber 20 when the intake valve 110 is closed (where the exhaust valve 140 is already closed) during the intake stroke or compression stroke and the volume of the combustion chamber 20 when the piston 50 is at top dead center. The effective compression ratio can also take into account the blowby of the charge through the piston ring (not shown), which is disposed between the piston 50 and the cylinder 60 and seals the combustion chamber 20. The geometric compression ratio value and the available effective compression ratio value are programmed in the controllers 150 and 151 herein, so that these controllers know the current compression ratio. The higher the ICT and ICP, the higher the temperature and pressure in the combustion chamber throughout the compression stroke, respectively. Some fuels have a higher flame speed, so the fuel jets of these fuels, compared with fuels with lower flame speeds, exhibit shorter flame lift distances from the nozzle 190 of the in-cylinder injector 180 and the nozzle 191 of the in-cylinder injector 181, respectively. As used herein, the flame lift distance of a fuel jet refers to the shortest distance between the opening of the jet hole from which the fuel jet originates and the location where the fuel jet burns, measured along the path of the fuel jet (i.e., the closest distance of the flame of the burning fuel jet to the jet hole). A shorter lift distance may result in an increased thermal load on the nozzles 190 and 191, thereby increasing the temperature of the nozzles 190 and 191, including the internal temperature within the chamber 285. The fuel type or fuel composition may also be programmed into the controllers 150 and 151; however, in some embodiments, more than two types of fuels or fuels with different compositions may be employed in the internal combustion engines 10 and 11, thereby possibly requiring the fuel type or fuel composition to be determined during operation.In these cases, various techniques may be employed to determine the heating value of the fuel, and the heating value may be used to determine the fuel type or fuel composition by inference, such as using an oxygen sensor to detect residual oxygen in the exhaust, using a hot wire sensor in the fuel conduit to detect the thermal properties of the fuel, and using an accelerometer to detect the ignition properties and combustion properties in the combustion chamber, to name just a few examples. It should be understood that the controllers 150 and 151 also know the fuel type and / or fuel composition that the internal combustion engines 10 and 11 are currently being supplied with fuel. Secondary factors that affect the self-ignition in the chamber 285 include the inlet manifold pressure (IMP), the inlet manifold temperature (IMT), the exhaust gas recirculation (EGR) concentration, the engine speed, and the engine load. The higher the IMP and IMT, the greater the likelihood that self-ignition will occur in the chamber 285, while the higher the EGR concentration, the less likely pre-ignition will occur. Typically, the EGR concentration has a smaller effect on the ignition delay, and significantly more influences the flame temperature and flame speed. These engine operating state parameters (IMP, IMT, EGR concentration, engine speed, engine load) are conventional parameters that are measured and available to electronic controllers in conventional internal combustion engines, and may be used in controllers 150 and 151 herein.

[0037] Reference now Figure 5, a graphical view 400 shows the auto-ignition limits of 500 microseconds (μs) delay for various fuel / air equivalence ratios (also referred to as φ) plotted against normalized values ​​of temperature and pressure. Lines 410, 420, 430, and 440 represent the 500 microsecond delay limits for fuel-air mixtures having fuel / air equivalence ratios (φ) of 0.5, 1.0, 1.5, and 2.0, respectively. A fuel / air equivalence ratio below 1.0 represents a lean fuel-air mixture (where there is more oxygen than is required to burn all of the fuel), a fuel / air equivalence ratio equal to 1.0 represents a stoichiometric fuel-air mixture (where there is just enough oxygen to burn all of the fuel), and a fuel / air equivalence ratio above 1.0 represents a rich fuel-air mixture (where there is not enough oxygen to burn all of the fuel). For each fuel / air equivalence ratio, the area above lines 410, 420, 430 and 440 represents conditions that are more favorable to self-ignition, the area below lines 410, 420, 430 and 440 represents less favorable conditions, and these less favorable conditions ultimately prevent self-ignition. More specifically, for temperature and pressure points that are further below the corresponding lines 410, 420, 430 and 440, the self-ignition delay increases. It should be understood that in an internal combustion engine, in the absence of combustion, the temperature and pressure in the combustion chamber 20 (and chamber 285) rise during the compression stroke and then begin to decrease during the expansion stroke (after the piston 50 passes TDC at the end of the compression stroke), the opportunity for ignition to occur is limited (during the pre-ignition window). At least a portion of the main fuel in the combustion chamber 20 or chamber 285 must reach temperature and pressure conditions suitable for self-ignition, and then maintain the conditions during the self-ignition delay before it can ignite. As an example, in a four-stroke engine running at 2000 rpm, the compression stroke lasts 15 milliseconds (ms); however, the pre-ignition window is a fraction of that time because the temperature and pressure must first increase to conditions that make auto-ignition possible, and then those conditions must be maintained during the auto-ignition delay before ignition can occur. Typically, the maximum auto-ignition delay in a heavy-duty internal combustion engine is about 1-2 ms, depending on the engine speed. Figure 5As shown, as the fuel / air equivalence ratio increases (becomes richer), the temperature required for self-ignition decreases for a given pressure. However, at a certain point, the mixture becomes too rich to burn, and similarly, as the mixture gradually becomes leaner, it eventually becomes too lean to burn. It is conjectured that in the case where the fuel-air mixture is too rich to burn in chamber 285, before the fuel-air mixture reaches the upper flammability limit, the temperature of the fuel-air mixture in chamber 285 decreases due to the cooling effect of the main fuel leaking through main injection valve 250, thereby creating a condition where self-ignition is impossible. Each horizontal line 450, 460, 470 and 480 represents the temperature state and pressure state of the compression end of a unique compression ratio (each compression ratio is represented by a normalized value in the graph), where the compression ratios of the lines are line 450, line 460, line 470 and line 480 in descending order. Each horizontal line 450, 460, 470 and 480 has one compression end temperature, but has a range of compression end pressures. In this regard, each horizontal line 450, 460, 470, and 480 represents one in-cylinder temperature (inside the combustion chamber 20) at the beginning of compression and a plurality of in-cylinder pressures at the beginning of compression. For each horizontal line 450, 460, 470, and 480, the initial combustion chamber pressure increases from left to right, with three cases (P O =0.5 bar, 1 bar and 3 bar), so that the compression end pressure also increases from left to right. It can be seen that the pressure and temperature conditions along line 450 present multiple possible conditions that allow auto-ignition in chamber 285 for richer equivalence ratios (φ=1.0, 1.5 and 2.0) because the area above the line 420, line 430 and part of the line 440 includes the part of the line 450. On the other hand, the pressure and temperature conditions along lines 460, line 470 and line 480 do not present multiple possible conditions that allow auto-ignition in chamber 285 for the equivalence ratios shown because the area above the line 410, line 420, line 430 and line 440 does not include (at least substantially does not include) the part of the line 460, line 470 and line 480.

[0038] Reference now Figure 6 , a flow chart of an algorithm 500 for mitigating auto-ignition within chamber 285 is shown. Algorithm 500 and all other algorithms disclosed herein may be implemented by Figure 1 The controller 150 in the engine 10 and Figure 3The controller 151 in the engine 11 is executed. One or more engine operating state parameters are collected in step 510 and input into step 520, and it is determined in step 520 whether auto-ignition is possible in the chamber 285. The engine operating state parameters used in step 520 can be selected from the group consisting of compression ratio, fuel type or fuel composition, ICT, IMP, IMT, EGR concentration, engine speed and engine load. When auto-ignition is not possible in the chamber 285, fuel injection is performed according to the standard engine control parameter map 530, wherein the standard engine control parameter map may include any one of the following injection parameters: injection timing, injection amount, injection pressure, number of injection pulses, pulse width of each pulse, and interval between pulses, wherein these injection parameters may be based on the engine operating state. More specifically, the standard engine control parameter map 530, when used for engine 10, includes pilot fuel injection timing information and pilot fuel injection amount information and main fuel injection timing information and main fuel injection amount information based on the engine operating state; and the standard engine control parameter map 530, when used for engine 11, includes main fuel injection timing information and main fuel injection amount information based on the engine operating state. When auto-ignition is possible in chamber 285, a mitigation strategy 540 is executed, wherein the mitigation strategy reduces the possibility of auto-ignition in chamber 285 and preferably prevents auto-ignition in chamber 285. After or during the mitigation of auto-ignition, fuel injection is performed using the modified engine control parameter map 550. Similarly, the modified engine control parameter map 550 may include the same injection parameter information as the standard engine control parameter map 530, such as injection timing and injection amount information of the pilot fuel and / or the main fuel, depending on which engine 10 or 11 the modified engine control parameter map 550 is used for. The injection parameter information may change between the standard engine control parameter map 530 and the modified engine control parameter map 550, particularly when the mitigation strategy 540 includes injection of the main fuel (as discussed in more detail below), but for the same engine operating state, there may be circumstances where some or all of the injection parameter information does not change.

[0039] Reference now Figure 7 , shows a flow chart of an algorithm 560, which can be used to Figure 6The mitigation strategy 540 in the algorithm 500 of . The critical crank angle is calculated in step 562. The critical crank angle is the earliest crank angle at which auto-ignition may occur during the compression stroke. As described above, the ignitable fuel-air mixture in the chamber 285 must be maintained at the auto-ignition temperature (in a pressure and temperature environment suitable for auto-ignition) during a period of time, which is equal to the auto-ignition delay of igniting the ignitable fuel-air mixture. The critical crank angle represents the point during the compression stroke at which this state becomes possible, and marks the beginning of the pre-ignition window, which can end at the latest during the expansion stroke (as discussed in more detail above). The critical crank angle can be calculated as a function of an engine operating state parameter, which is used to determine whether auto-ignition is possible in the chamber 285, and the engine operating state parameter can include one or more of the following parameters, which include compression ratio, fuel type or fuel composition, IMP, IMT, EGR concentration, engine speed and engine load. In step 564, a mitigation amount of main fuel is calculated, which represents the amount of main fuel required to be injected into the combustion chamber 20 through the chamber 285 before the critical crank angle to prevent self-ignition in the chamber 285. Self-ignition in the chamber 285 can be prevented for the remainder of the current engine cycle. Alternatively, self-ignition in the chamber 285 can be prevented at least until the main injection of the main fuel occurs later during the current compression stroke. The injection of the mitigation amount of main fuel makes the fuel-air mixture in the chamber 285 (if there is any air remaining) unable to be ignited. The fuel-air mixture becomes unable to be ignited for various reasons. Preferably, by the injection of the mitigation amount of main fuel, the oxidant in the chamber 285 is flushed out of the main bag and into the combustion chamber 20, so that there is no oxidant in the main bag after the injection. It is also possible that a new fuel-air mixture is formed in the chamber 285, which is too rich to burn (that is, some oxidant remains in the chamber 285). Alternatively, the injection of the moderate amount of main fuel may cool the fuel-air mixture so that the new fuel-air mixture formed is below the auto-ignition temperature. The injection of the moderate amount of main fuel is performed in step 566 before the piston 50 reaches the critical crank angle. In other embodiments, there may be more than one moderate injection of main fuel before the main injection of main fuel occurs.

[0040] refer to Figure 8 , the chart view 570 shows that for Figure 1 An internal combustion engine 10, Figure 7 The algorithm 560 is used for Figure 6The fuel injection flow rate when in the algorithm 500 of . A moderate injection 572 of a moderate amount of main fuel is performed before the piston 50 reaches the critical crank angle 574 to clear oxygen in the chamber 285, thereby forming a fuel-air mixture that is too rich to burn (and preferably does not contain an oxidizer) to prevent self-ignition in the main bag. The moderate injection 572 of the main fuel also reduces the temperature in the chamber 285 by cooling the fuel-air mixture in the chamber 285, which also reduces the possibility of self-ignition in the main bag. The critical crank angle 574 is the crank angle during the compression stroke at which point forward self-ignition in the chamber 285 is possible when both fuel and oxidizer are present in the chamber 285 and no measures are taken to prevent self-ignition, and wherein self-ignition does not occur in the chamber 285 before the critical crank angle when an ignitable fuel-air mixture is present in the chamber 285. The critical crank angle 574 may be a function of primary factors (compression ratio and fuel type or fuel composition) and may additionally be a function of secondary factors (IMP, IMT, EGR concentration, engine speed, engine load). After the mitigation injection 572 and typically after the critical crank angle 574, a pilot injection 576 of the pilot fuel and a main injection 578 of the main fuel are performed. In the illustrated embodiment, the pilot injection 576 precedes the main injection 578; however, this is not required and various timings of the pilot and main injections may be employed. Return Figure 6 The standard engine control parameter map 530 also includes the amount of main fuel to be injected and to be ignited by the pilot injection, which is related to Figure 8 The amount of main fuel injected in the standard engine control parameter map 530 is substantially equal to the amount of main fuel injected by the softening injection 572 and the main injection 578 in the modified engine control parameter map 550 (see Figure 8 )The sum of the main fuel injected.

[0041] refer to Fig. 9 , the chart view 580 shows that for Figure 3 The internal combustion engine 11, Figure 7 The algorithm 560 is used for Figure 6The fuel injection flow rate when in the algorithm 500. The engine 11 is a single fuel engine, so the combustion of the pilot fuel is not used to ignite the main fuel. Instead, when a suitable pressure and temperature environment is generated in the combustion chamber 20, the ignition of the main fuel is achieved by the self-ignition of the main fuel in the combustion chamber 20. In order to ensure that the fuel-air mixture in the chamber 285 is not pre-ignited before the main fuel is injected, a moderate injection 582 of a moderate amount of the main fuel is performed before the critical crank angle 584 (calculated in the same manner as above) to exhaust oxygen from the chamber 285 and / or cool the fuel-air mixture in the chamber 285. The portion of the fuel from the moderate injection 582 of the moderate amount of the main fuel that enters the combustion chamber 20 can automatically ignite and improve the pressure and temperature environment in the combustion chamber 20 to ignite the main fuel introduced by the main injection 586. That is, the moderate injection 582 can operate as a pilot injection of the main fuel, and the combustion of the moderate injection improves the ability of the main fuel introduced by the main injection 586 to ignite. However, it is not required that the combustion of the mild injection requires the ignition of the main fuel for the main injection. Figure 6 The standard engine control parameter map 530 also includes the amount of main fuel to be injected and to be ignited by auto-ignition, which is related to Fig. 9 586. Generally, when auto-ignition is possible in combustion chamber 20, auto-ignition is also possible in chamber 285. In this regard, a mitigation injection 582 is generally used, but there may be engine operating conditions where auto-ignition is not possible in chamber 285 before main injection 586. Generally, the amount of main fuel injected in the standard engine control parameter map 530 is substantially equal to the amount of main fuel injected in the modified engine control parameter map 550 by mitigation injection 582 and main injection 586 (see Fig. 9 )The sum of the main fuel injected.

[0042] Reference now Fig.10 , showing a flow chart of an algorithm 590, which can be used to Figure 6The mitigation strategy 540 in the algorithm 500 is used. In step 594, the critical compression ratio is calculated using one or more engine operating state parameters collected in step 592. The critical compression ratio is the minimum compression ratio required for auto-ignition to occur in the chamber 285 and is a function of one or more engine operating state parameters, such as one or more of the fuel type or fuel composition, ICT, IMP, IMT, EGR concentration, engine speed and engine load. In step 596, the effective compression ratio of the internal combustion engine 10 or 11 is adjusted so that the effective compression ratio is less than the critical compression ratio, thereby preventing auto-ignition from occurring in the chamber 285. By reducing the effective compression ratio, the pressure and temperature conditions in the chamber 285 are no longer suitable for auto-ignition of the fuel-air mixture therein. The effective compression ratio can be changed by adjusting the valve timing of the intake valve 110 by the VVT ​​or VVA system. The amount by which the intake valve timing is adjusted is a function of the critical compression ratio. Return Figure 6 , the standard engine control parameter map 530 is included in Fig.10 The amount of main fuel to be injected and ignited (by forced ignition of a pilot fuel or by auto-ignition, for example) is shown in the context of an algorithm 590 that adjusts the effective compression ratio. Since the thermal efficiency of the engines 10 and 11 changes when the effective compression ratio changes, the amount of main fuel injected and / or the timing of the main fuel injection in the modified engine control parameter map 550 may be adjusted compared to the standard engine control parameter map 530. For example, when the effective compression ratio decreases, the fuel supply of the main fuel is increased to compensate for the decrease in power output. When the effective compression ratio changes, the ignition delay may also change, so that the start of the injection timing may need to be corrected to maintain the preferred combustion timing.

[0043] Reference now Fig.11 , shows a flow chart of an algorithm 600, which can be used to Figure 6 The mitigation strategy 540 in the algorithm 500 of FIG. 6 is shown. At step 604, the coolant flow through the charge air cooler (CAC) is increased to reduce the IMT (and therefore reduce the ICT) so that the temperature within the chamber 285 is reduced to below the auto-ignition temperature. In the context of the algorithm 600, when the IMT is reduced, the ICT at the beginning of the compression stroke is reduced, and when the IMT is increased, the ICT at the beginning of the compression stroke is increased. The coolant flow increase can be a function of one or more of the critical crank angle, compression ratio, current IMT, current ICT, current IMP, engine speed, and engine load. The charge air cooler is a heat exchanger that cools the intake air compressed by the turbocharger ( FIG. 10 ) before it flows into the intake manifold (not shown) and the intake port 100. Figure 1 or Figure 3(not shown). The response time to reduce the IMT and ICT by increasing the coolant flow through the CAC may require multiple combustion cycles to complete. Therefore, the technique of algorithm 600 can operate in a predictive manner by reducing the IMT before auto-ignition in chamber 285 becomes a problem. The prediction of when to begin reducing the IMT can be based on current and historical values ​​of one or more of the engine operating state parameters. In contrast, any of the techniques of injecting a moderate amount of main fuel and adjusting the intake valve timing can prevent auto-ignition within the combustion cycle where these techniques are first used. When the IMT is adjusted, it can be periodically updated in step 520 (see Figure 6 ), used to determine whether auto-ignition is possible in chamber 285. Return Figure 6 , the standard engine control parameter map 530 is included in Fig.11 The amount of main fuel to be injected and ignited (either by forced ignition like a pilot fuel or by self-ignition) in the context of the algorithm 600 for adjusting the IMT is shown. The amount of main fuel injected and / or the timing of the main fuel injection in the modified engine control parameter map 550 can be adjusted compared to the standard engine control parameter map 530 to compensate for the different pressure and temperature environment in the combustion chamber 20 caused by the change in IMT. For example, a higher IMT generally results in faster ignition and lower thermal efficiency, so that in order to maintain the same engine power output, it is necessary to increase the fuel supply of the main fuel and delay the start of injection timing.

[0044] In other embodiments, the mitigation strategies disclosed in algorithms 560, 590, and 600 for reducing the likelihood of, and preferably preventing, self-ignition in chamber 285 may operate in concert to increase the effectiveness of preventing self-ignition in chamber 285. As an example, Fig.10 Algorithm 590 (adjusting the effective compression ratio) in Fig.11 Algorithm 600 (adjusting IMT) in is executed in parallel. As another example, Fig.10 The algorithm 590 in can be compared with Figure 7560 (perform mild injection) in 600. One advantage of combining algorithm 590 with another, algorithm 560 or algorithm 600 is that reducing the effective compression ratio of internal combustion engines 10 and 11 also reduces the thermal efficiency of these engines, thereby reducing fuel economy and reducing peak power. By combining algorithm 590 with algorithm 560 or algorithm 600, the effective compression ratio does not have to be reduced too much to prevent auto-ignition in chamber 285. In some cases, the effective compression ratio may not be reduced enough to prevent auto-ignition, and in these cases, it is advantageous to combine algorithm 590 (reducing the effective compression ratio) with algorithm 560 (perform mild injection) or algorithm 600 (reducing IMT) to reduce and preferably prevent auto-ignition in chamber 285.

[0045] Reference now Fig.12 , an algorithm 700 for reducing and preferably preventing auto-ignition in chamber 285 is shown, which can be used to operate the internal combustion engine 10 in a single fuel mode where no pilot fuel is required to ignite the main fuel, or can be used to operate the internal combustion engine 11 as a single fuel engine. In step 720, one or more engine operating state parameters 710 including compression ratio, fuel type or fuel composition, ICT, IMT, IMP, EGR concentration, engine speed and engine load are used to determine whether auto-ignition is possible in the combustion chamber 20. In the event that auto-ignition is not possible, control is transferred to step 730, where an auto-ignition enhancement mitigation strategy is executed to create a condition in the combustion chamber 20 where auto-ignition is possible. In the event that auto-ignition is possible in the combustion chamber 20, control is transferred to step 560 (in Figure 7 Detailed description can be seen in ), wherein a mitigation injection strategy is executed to prevent self-ignition from occurring in chamber 285, the mitigation injection strategy including calculating a critical crank angle, calculating a mitigation injection amount, and executing mitigation injection. Generally, when self-ignition is possible in combustion chamber 20, self-ignition is possible in chamber 285. Therefore, steps are taken in algorithm 700 to reduce and preferably prevent self-ignition from occurring in chamber 285, while allowing self-ignition to occur in combustion chamber 20. This is achieved by executing a mitigation injection strategy (i.e., Figure 7 The amount of main gas injection is determined by taking into account the amount of the mitigation injection. The mitigation injection can also perform the function of igniting and burning in the combustion chamber 20 to create a more optimal environment (in terms of pressure and temperature) in the combustion chamber 20 for igniting the main fuel from the main gas injection.

[0046] refer to Fig.13 , the algorithm 800 for adjusting the effective compression ratio to produce conditions that allow autoignition can be used Fig.12The auto-ignition enhancement mitigation strategy 730 shown in FIG. 804 is used to calculate the critical compression ratio using one or more engine operating state parameters 802, such as fuel type or fuel composition, ICT, IMT, IMP, EGR concentration, engine speed, and engine load, and if possible, the effective compression ratio is adjusted to be equal to or greater than the critical compression ratio in step 806. In some cases, the critical compression ratio may be greater than the geometric compression ratio, making it impossible to increase the effective compression ratio beyond the geometric compression ratio. In this case, different techniques or auxiliary measures are required to produce the conditions required for auto-ignition in the combustion chamber 20. Reference Fig.14 , algorithm 810 may alternatively or additionally be used as Fig.12 800 (increasing the effective compression ratio) and the techniques of algorithm 810 (increasing IMT and ICT) may be used together, and are typically used in parallel.

[0047] Reference now Fig.15 , shows an algorithm 900 for determining whether to operate the engine 10 in a single fuel auto-ignition mode or a forced ignition mode. In step 920, one or more engine operating state parameters 910, such as fuel type or fuel composition, IMT, IMP, EGR concentration, engine speed and engine load, are used to determine the critical compression ratio CRc, which is then compared with the geometric compression ratio CR in step 930. G When the critical compression ratio is not greater than the geometric compression ratio, the single fuel auto-ignition mode 940 is selected, and when the critical compression ratio is greater than the geometric compression ratio, the forced ignition mode 950 is selected. In the forced ignition mode, another means is used to ignite the main fuel, such as a pilot fuel in an embodiment of the engine 10, or a spark plug, glow plug or other heating surface in other embodiments. The pilot fuel, such as diesel fuel, has a higher cetane number than the main fuel and is therefore ignitable under temperature and pressure conditions where the main fuel is not ignitable.

[0048] The boost pressure from the turbocharger affects the inlet manifold pressure. The boost pressure can have a mild effect on the ignition delay time, and therefore can affect the self-ignition of the main fuel, wherein increasing the boost pressure increases the possibility of self-ignition in the combustion chamber 20 and chamber 285, and reducing the boost pressure reduces the possibility of self-ignition in the combustion chamber 20 and chamber 285. Reducing the boost pressure can lead to higher exhaust temperature and lower efficiency. The upper limit of the boost pressure is controlled by the turbo compressor efficiency, the peak cylinder pressure and the available enthalpy in the exhaust gas, so the range in which the boost pressure can be changed is very limited. On the other hand, the intake manifold temperature has a stronger effect on the self-ignition of the main fuel.

[0049] While particular elements, embodiments, and applications of the present invention have been shown and described, it should be understood that the invention is not limited thereto since modifications may be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.

Claims

1. An apparatus for managing ignition in a chamber within an in-cylinder injector, the in-cylinder injector introducing fuel directly into a combustion chamber of an internal combustion engine, the chamber including at least one injection hole and the chamber being in fluid communication with the combustion chamber through the at least one injection hole, the apparatus comprising a controller operatively connected to the in-cylinder injector and programmed to: selectively actuating the in-cylinder injector to inject the fuel directly into the combustion chamber; determining whether auto-ignition is likely in the chamber based on engine operating parameters; and When auto-ignition is possible, a mitigation strategy is implemented to prevent auto-ignition within the chamber of the in-cylinder injector.

2. The device according to claim 1, wherein: The controller is also programmed to use a standard engine control parameter map when auto-ignition is not possible and to use a modified engine control parameter map when auto-ignition is possible.

3. The device according to claim 1, wherein: The engine operating parameters are one or more of geometric compression ratio, effective compression ratio, fuel type, fuel composition, intake charge temperature, inlet manifold pressure, inlet manifold temperature, exhaust gas recirculation concentration, engine speed, and engine load.

4. The device according to claim 1, wherein: In executing the mitigation strategy, the controller is programmed to: determining a critical crank angle during a compression stroke when auto-ignition becomes possible in the chamber; determining a mitigating amount of fuel that needs to be injected prior to the critical crank angle to prevent auto-ignition in the chamber; and The in-cylinder injector is actuated to perform moderate injection of the moderate amount of fuel before the piston traveling in the combustion chamber during the compression stroke reaches the critical crank angle.

5. The device according to claim 4, wherein: The moderated amount of fuel prevents auto-ignition in the chamber at least until a main injection of fuel occurs later during the compression stroke.

6. The device according to claim 1, wherein: In executing the mitigation strategy, the controller is programmed to: determining a critical compression ratio that produces a pressure and temperature environment in the chamber suitable for auto-ignition; and The effective compression ratio is adjusted so that the effective compression ratio is less than the critical compression ratio.

7. The device according to claim 6, wherein: The critical compression ratio is calculated as a function of at least one engine operating parameter selected from the group consisting of fuel type, fuel composition, intake charge temperature, inlet manifold pressure, inlet manifold temperature, exhaust gas recirculation concentration, engine speed, and engine load.

8. The device according to claim 1, wherein: When executing the mitigation strategy, the controller is programmed to increase coolant flow through the charge air cooler to reduce inlet manifold temperature or intake charge temperature at the beginning of the compression stroke.

9. The device according to claim 1, wherein: The controller is also programmed to execute a second mitigation strategy when auto-ignition of fuel within the combustion chamber is not possible.

10. The device according to claim 9, wherein: When executing the second mitigation strategy, the controller is programmed to: determining a critical compression ratio that produces a pressure and temperature environment in the combustion chamber suitable for auto-ignition; and The effective compression ratio is adjusted so that the effective compression ratio is greater than or equal to the critical compression ratio.

11. The device according to claim 9, wherein: When executing the second mitigation strategy, the controller is programmed to reduce coolant flow through the charge air cooler to increase inlet manifold temperature or intake charge temperature at the beginning of the compression stroke.

12. A method for managing ignition in a chamber within an in-cylinder injector that introduces fuel directly into a combustion chamber of an internal combustion engine, the chamber including at least one injection hole and the chamber being in fluid communication with the combustion chamber through the at least one injection hole, the method comprising: determining whether auto-ignition is possible in the chamber based on engine operating parameters; and When auto-ignition is possible, a mitigation strategy is implemented to prevent auto-ignition within the chamber of the in-cylinder injector.

13. The method according to claim 12, wherein: When auto-ignition is not possible, a standard engine control parameter map is used, and when auto-ignition is possible, a modified engine control parameter map is used.

14. The method according to claim 12, wherein: The engine operating parameters are one or more of geometric compression ratio, effective compression ratio, fuel type, fuel composition, intake charge temperature, inlet manifold pressure, inlet manifold temperature, exhaust gas recirculation concentration, engine speed, and engine load.

15. The method according to claim 12, wherein: The mitigation strategies include: determining a critical crank angle during a compression stroke when auto-ignition becomes possible in the chamber; determining a mitigating amount of fuel that needs to be injected prior to the critical crank angle to prevent auto-ignition in the chamber; and A moderate injection of the moderate amount of fuel is performed before the piston traveling in the combustion chamber during the compression stroke reaches the critical crank angle.

16. The method according to claim 15, wherein: The moderated amount of fuel prevents auto-ignition in the chamber at least until a main injection of main fuel occurs later during the compression stroke.

17. The method according to claim 12, wherein: The mitigation strategies include: determining a critical compression ratio that produces a pressure and temperature environment in the chamber suitable for auto-ignition; and The effective compression ratio is adjusted so that the effective compression ratio is less than the critical compression ratio.

18. The method according to claim 17, wherein: The critical compression ratio is calculated as a function of at least one engine operating parameter selected from the group consisting of fuel type, fuel composition, intake charge temperature, inlet manifold pressure, inlet manifold temperature, exhaust gas recirculation concentration, engine speed, and engine load.

19. The method according to claim 12, wherein: The mitigation strategy includes increasing coolant flow through the charge air cooler to reduce the inlet manifold temperature or intake charge temperature at the beginning of the compression stroke.

20. The method according to claim 12, wherein: When auto-ignition of the fuel within the combustion chamber is not possible, a second mitigation strategy is implemented.

21. The method according to claim 20, wherein the second mitigation strategy comprises: determining a critical compression ratio that produces a pressure and temperature environment in the combustion chamber suitable for auto-ignition; and The effective compression ratio is adjusted so that the effective compression ratio is greater than or equal to the critical compression ratio.

22. The method of claim 20, the second mitigation strategy comprising reducing coolant flow through a charge air cooler to increase inlet manifold temperature or intake charge temperature at the beginning of a compression stroke.

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