Combustion control of ammonia-fueled engines

Abstract

The subject matter herein may be embodied, inter alia, in a method performed in connection with an internal combustion engine, the method including the steps of receiving a pressure signal from a combustion chamber pressure sensor while a volume is in a first range, the first range corresponding to a portion of a compression phase, the received pressure being a first pressure; supplying a first pulse of fuel at a first location of the body during the compression phase based on the received pressure signal; and supplying a second pulse of fuel at a second location of the body during the compression phase based on the received pressure signal.

Description

[Technical field]

[0001] This application claims priority to U.S. patent application 63 / 248,877, filed September 27, 2021, and U.S. patent application 17 / 935,495, filed September 26, 2022, and incorporates the entire contents of those U.S. patent applications by reference.

[0002] This disclosure relates to combustion and emissions control for dual fuel engines. [Background technology]

[0003] Internal combustion engines, including diesel and diesel-ammonia dual fuel engines, ignite an air-fuel mixture to produce combustion in one or more engine cylinders. A typical internal combustion engine system injects fuel and air into the engine's combustion chamber (e.g., cylinder) and ignites the fuel-air mixture using an ignition device such as a spark plug, a pilot quantity of diesel fuel for compression ignition, or via volumetric auto-ignition. In response to consumer and regulatory demands, conventional internal combustion engines are pushing the limits of combustion toward more fuel-efficient operating modes, such as using lean, advanced, or low-temperature combustion to reduce fuel combustion. However, diesel-ammonia combustion results in the production of nitrous oxide as an exhaust pollutant and the emission of excess ammonia fuel (i.e., ammonia slip). Summary of the Invention

[0004] Generally, systems and methods for combustion and emissions control in a dual fuel engine are described herein.

[0005] In a first example, an apparatus for controlling operation of an internal combustion engine includes a body sealed to a combustion chamber, the body movable to a top dead center position to compress at least one of a gas or a gas / liquid mixture in a compression phase and movable from the top dead center position by expanding combustion gases in an expansion phase, each position of the body defines a volume of the combustion chamber, the apparatus includes a processor that receives input from a position sensor configured to sense a position of the body corresponding to the volume of the combustion chamber and an input from a combustion chamber pressure sensor, the processor configured to receive a pressure signal from the combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of the compression phase, the received pressure being the first pressure, and based on the received pressure signal, provides a first signal configured to deliver a first pulse of fuel at the first position of the body during the compression phase, and based on the received pressure signal, provides a second signal configured to deliver a second pulse of fuel at a second position of the body during the compression phase.

[0006] In a second example related to the first example, the first signal is further configured to prepare an air / fuel mixture that is near auto-ignition upon compression.

[0007] In a third example related to the first or second examples, the second signal is further configured to initiate combustion in the combustion chamber.

[0008] In a fourth example related to any of the first to third examples, the second signal is further configured to control at least one of CA50 or CA10.

[0009] In a fifth example related to any of the first through fourth examples, the second signal is further configured to control a ratio of NH3 / NOx resulting from combustion of diesel fuel, ammonia fuel and air.

[0010] In a sixth example relative to the fifth example, the ratio is about 1.

[0011] In a seventh example relative to the sixth example, the ratio is less than about 1.2.

[0012] In an eighth example related to any of the first to seventh examples, the apparatus further includes an exhaust aftertreatment system configured to receive free ammonia present in the exhaust gas and catalyze NOx based on the ammonia.

[0013] In a ninth example, a method performed in connection with an internal combustion engine having a body sealed in a combustion chamber, the body being movable to a point position to compress at least one of a gas or a gas / liquid mixture in a compression phase and movable from the point position by expanding combustion gases in an expansion phase, each position of the body defining a volume of the combustion chamber, the method including receiving a pressure signal from a combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of the compression phase, the received pressure being a first pressure, delivering a first pulse of fuel at the first position of the body during the compression phase based on the received pressure signal, and delivering a second pulse of fuel at a second position of the body during the compression phase based on the received pressure signal.

[0014] In a tenth example related to the ninth example, the first pulse of fuel is further configured to prepare an air / fuel mixture close to auto-ignition.

[0015] In an eleventh example related to the ninth or tenth examples, the method further comprises initiating combustion in the combustion chamber based on a second pulse of fuel.

[0016] In a twelfth example relating to any of the ninth to eleventh examples, the method further comprises controlling at least one of CA50 or CA10 based on at least one of the first pulse of fuel or the second pulse of fuel.

[0017] In a thirteenth example related to any of the ninth to twelfth examples, the method further comprises controlling a ratio of NH3 / NOx resulting from combustion of diesel fuel, ammonia fuel, and air based on at least one of the first pulse of fuel or the second pulse of fuel.

[0018] In the fourteenth example, which is related to the thirteenth example, the ratio is about one.

[0019] In a fifteenth example related to the fourteenth example, the ratio is less than about 1.2.

[0020] In a 16th example relating to any of the 9th to 15th examples, the method further includes a step of receiving free ammonia present in the exhaust gas by an exhaust aftertreatment system, and a step of catalyzing NOx based on the free ammonia by the exhaust aftertreatment system.

[0021] In a seventeenth example related to the sixteenth example, the method further includes controlling the amount of free ammonia present in the exhaust gas based on at least one of the first pulse of fuel or the second pulse of fuel.

[0022] In an example embodiment, an apparatus for controlling operation of an internal combustion engine having a body sealed with a combustion chamber, the body movable to a top dead center position to compress at least one of a gas or a gas / liquid mixture in a compression phase and movable from the top dead center position by expanding combustion gases in an expansion phase, each position of the body defining a volume of the combustion chamber, the apparatus comprising a processor receiving input from a position sensor configured to sense a position of the body corresponding to the volume of the combustion chamber and an input from a combustion chamber pressure sensor, the processor being configured to receive a pressure signal from the combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of the compression phase, the received pressure being a first pressure, providing a first signal configured to deliver a first pulse of fuel at the first position of the body during the compression phase based on the received pressure signal, and providing a second signal configured to deliver a second pulse of fuel at a second position of the body during the compression phase based on the received pressure signal.

[0023] Various embodiments may include some, all, or none of the following features: The first signal may be configured to prepare an air / fuel mixture near auto-ignition. The second signal may be further configured to initiate combustion in the combustion chamber. The second signal may be configured to control at least one of the CA50 or CA10. The second signal may be configured to control a ratio of NH3 / NOx resulting from combustion of diesel fuel, ammonia fuel, and air. The ratio may be greater than about 1, 1.2. The apparatus may include an exhaust aftertreatment system configured to receive free ammonia present in the exhaust gas and catalyze NOx based on the ammonia.

[0024] In one implementation, a method is performed in association with an internal combustion engine including a body sealed to a combustion chamber, the body movable to a point location to compress at least one of a gas or a gas / liquid mixture in a compression phase and movable from the point location by expanding the combustion gases in an expansion phase, each position of the body defining a volume of the combustion chamber, the method including receiving a pressure signal from a combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of the compression phase, the received pressure being a first pressure, delivering a first pulse of fuel at the first position of the body during the compression phase based on the received pressure signal, and delivering a second pulse of fuel at a second position of the body during the compression phase based on the received pressure signal.

[0025] Various implementations may include some, all, or none of the following features. The first pulse of fuel may be further configured to prepare an air / fuel mixture close to auto-ignition. The method may include initiating combustion in the combustion chamber based on the second pulse of fuel. The method may include controlling a CA50 based on at least one of the first pulse of fuel or the second pulse of fuel. The method may include controlling a ratio of NH3 / NOx resulting from combustion of diesel fuel, ammonia fuel, and air during the expansion phase based on at least one of the first pulse of fuel or the second pulse of fuel. The ratio may be about 1. The ratio may be between 1.0 and about 1.2. The method may include receiving, by an exhaust aftertreatment system, free ammonia present in the exhaust gas and catalyzing, by the exhaust aftertreatment system, NOx based on the free ammonia. The method may include controlling an amount of free ammonia present in the exhaust gas based on at least one of the first pulse of fuel or the second pulse of fuel.

[0026] The systems and techniques described herein may provide one or more of the following advantages: First, the system may improve the usability of ammonia as a renewable fuel source (e.g., by improving the combustion of NH3, a difficult fuel to burn, which has the benefit of GHG reduction since NH3 itself contains no carbon). Second, the system may improve the emissions resulting from the combustion of the fuel (e.g., by using NH3 slip to reduce NOx in SCR). Third, the system may reduce or eliminate the need for premium urea (e.g., diesel exhaust fluid or "DEF") and associated delivery systems for use in exhaust gas aftertreatment systems.

[0027] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0028] [Figure 1] 1 is a schematic diagram illustrating an example of an internal combustion engine system.

[0029] [Diagram 2] 1 is a schematic cross-sectional view of a cylinder of an internal combustion engine including an engine control system;

[0030] [Diagram 3] FIG. 4 is a cross-sectional view of another cylinder of the internal combustion engine.

[0031] [Figure 4] 4 is a chart showing an example of a cylinder stroke. [Diagram 5] 4 is a chart showing an example of a cylinder stroke.

[0032] [Figure 6] FIG. 1 is a schematic diagram illustrating an example of an engine control system.

[0033] [Figure 7] FIG. 2 is a schematic half-sectional view showing an example of a gas mixer.

[0034] [Figure 8] 1 is a chart showing an example of gas concentrations resulting from in-cylinder combustion of ammonia.

[0035] [Figure 9] FIG. 1 is a schematic cross-sectional view of an example diesel aftertreatment system.

[0036] [Figure 10] 1 is a chart showing an example of exhaust gas products.

[0037] [Figure 11] FIG. 2 is a flow diagram illustrating an example process for controlling an internal combustion engine system.

[0038] [Figure 12] FIG. 1 is a schematic diagram illustrating an example of a general computer system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Low and zero carbon fuels are required for internal combustion engines. A technological goal in engine development is to achieve high efficiency and high power density while achieving it with near zero emissions.

[0040] Hydrogen is considered to be a leading candidate as a fuel to achieve these goals. Hydrogen is an excellent combustion fuel with low ignition energy, a wide AFR (air-fuel ratio), and a fast burning speed. However, pure hydrogen (H2) is energetically expensive to produce, and its natural state is a gas at standard conditions. Therefore, to be used for transportation, hydrogen must be pressurized (e.g., 10,000 psi) or liquefied (e.g., below -250°C), making it difficult to handle safely (due to leakage, explosiveness, etc.).

[0041] An alternative to pure H2 is to add nitrogen molecules to make ammonia (NH3). Ammonia has a higher energy density relative to H2 because it can be stored as a liquid at only about 15 psi gauge pressure. Ammonia can be used as a fuel, but it has almost the opposite properties to hydrogen. Ammonia is difficult to ignite, burns slowly, burns at a low temperature, and almost always requires some kind of combustion promotion. A practical method of introducing ammonia into the fuel is to vaporize the liquid ammonia in a suitable water-circulating heat exchanger and port inject it as a vapor. This is also known as port fuel injection (PFI), which creates a premixture of air and ammonia. It is also possible to inject the ammonia directly into the cylinder using a high-pressure direct injector, or in the case of dual fuel, a high-pressure dual fuel (HPDF) injector.

[0042] To improve the ignition of ammonia, diesel fuel can be used to improve the initiation and burn rate. Ammonia combustion in diesel can produce suboxides (NOx) and unburned ammonia (NH3), two emissions that have regulatory standards in addition to N2O, and can be produced if the catalyst is insufficient. NOx can result from the high temperature diesel-driven diffusion flame and available nitrogen in the atmosphere (e.g., 79% N2, 21% O2). Unburned ammonia results from a process similar to that known to cause methane slip (direct combustion short circuit, piston / cylinder wall gap area quench, bulk flame quench, etc.) in natural gas-fueled dual fuel engines, also referred to as ammonia slip. The systems and methods described herein control the combustion of ammonia in dual fuel applications such that both NOx emissions and ammonia slip (NH3) are reduced or eliminated in a controlled manner. Although described herein in the context of a diesel dual fuel application, similar concepts can be applied to other dual fuel applications that burn ammonia.

[0043] FIG. 1 illustrates an example of an engine system 100. The engine system 100 includes an intake manifold 104 combined with diesel fuel (e.g., via direct injection) and ammonia fuel (e.g., via port or direct injection) and fluidly coupled to an oxygen source (e.g., air). The engine system 100 is configured as a four-stroke (intake, compression, combustion, exhaust, etc.) engine. The engine system 100 includes a cylinder bank 102a with four cylinders and a cylinder bank 102b with four cylinders. The illustrated embodiment includes an eight-cylinder engine having two banks of four cylinders, although the engine system 100 may have any suitable number of banks with any suitable number of cylinders. Additionally, while the illustrated embodiment is depicted and described as a piston engine, aspects of the present disclosure may be applied to other types of internal combustion engines, such as rotary engines.

[0044] In a particular embodiment, a throttle 112 is positioned in an intake plenum 103 upstream of the intake manifold 104 to regulate the pressure in the intake manifold 104, for example, to control exhaust gas recirculation (EGR).

[0045] The exhaust manifold 106a is configured to receive combustion products (exhaust) from the combustion chambers of the cylinder bank 102a. That is, the exhaust manifold 106a is fluidly coupled to the outlets of the combustion chambers of the cylinder bank 102a. An EGR flow passage 108a or conduit fluidly couples the exhaust manifold 106a to an ammonia gas injector 114 configured to supply ammonia gas fuel to the intake manifold 104 (e.g., port injection of ammonia gas fuel). In some implementations, the ammonia gas injector 114 can be configured as a direct injection system configured to supply ammonia gas fuel directly to the combustion chambers. In the illustrated embodiment, an EGR throttle valve 126a is disposed in the gas flow passage 108a between the exhaust manifold 106a and the ammonia gas injector 114 and is used to regulate the EGR flow. In certain embodiments, an exhaust gas cooler 110a is positioned in the EGR flow passage 108a between the exhaust manifold 106a and the ammonia gas injector 114. The exhaust gas cooler 110a is operable to reduce the temperature of the exhaust gas before it enters the ammonia gas injector 114. The exhaust gas cooler 110a is a heat exchanger, such as an air-to-air exchanger or an air-to-water exchanger. In some implementations, the EGR flow may be recirculated to the intake manifold 104 upstream of the ammonia gas injector 114, downstream of the ammonia gas injector 114, or at the location of the ammonia gas injector 114.

[0046] The exhaust manifold 106b is configured to receive combustion products (exhaust) from the combustion chambers of the cylinder bank 102b. That is, the exhaust manifold 106b is fluidly coupled to the outlets of the combustion chambers of the cylinder bank 102b. An EGR flow passage 108b or conduit fluidly couples the exhaust manifold 106b to the intake manifold 104. In the illustrated embodiment, an EGR throttle valve 126b is disposed in the EGR flow passage 108b between the exhaust manifold 106b and the ammonia gas injector 114 and is used to regulate the EGR flow. The EGR throttle valve 126b regulates the EGR flow by adjusting the cross-sectional area of ​​the EGR flow passage 108b through the EGR throttle valve 126b.

[0047] The exhaust gas cooler 110b is positioned in the EGR flow path 108b between the exhaust manifold 106b and the ammonia gas injector 114. The exhaust gas cooler 110b is operable to reduce the temperature of the exhaust gas before it enters the ammonia gas injector 114. The exhaust gas cooler 110b is a heat exchanger, such as an air-to-air exchanger or an air-to-water exchanger.

[0048] In some implementations, the engine system 100 includes a compressor 118 upstream of the throttle 112. In an engine that has a compressor 118 but no throttle, such as an unthrottled diesel engine, the throttle 112 is not needed and the ammonia gas injector 114 may be downstream of the compressor 118. The compressor 118 may include a centrifugal compressor, a positive displacement compressor, or another type of compressor for increasing the pressure in the air in the intake plenum 103 during engine operation.

[0049] In the illustrated embodiment, the compressor 118 is part of a turbocharger; that is, a turbine 122 is located downstream of the exhaust manifolds 106a and 106b and rotates as the exhaust gases expand through the turbine 122. The turbine 122 is coupled to the compressor 118, for example via a shaft, to provide rotation to the compressor 118. Although the illustrated example depicts and describes a turbocharger to increase intake manifold pressure, other compression methods may be used, such as, for example, an electric or engine-driven compressor (e.g., a supercharger).

[0050] The engine system 100 includes an intercooler 120 configured to cool the compressed air in the intake plenum 103 before the compressed air enters the ammonia gas injector 114 and the intake manifold 104. The intercooler may operate to reduce the temperature of the compressed air before the intake manifold 104. The intercooler is a heat exchanger, such as an air-to-air exchanger or an air-to-water exchanger.

[0051] The fuel supply 130 is configured to provide fuel for combustion in the engine system 100 (e.g., the cylinders of the cylinder blocks 102a and 102b). In the illustrated example, the fuel supply 130 is configured to supply ammonia gas as fuel to the ammonia gas injector 114. An example of such a configuration is described in more detail in the description of FIG. 2. In some implementations, the fuel supply 130 can be configured to supply fuel to the intake plenum 103 (e.g., upstream of the throttle 112). In some implementations, the fuel supply 130 can be configured to supply fuel downstream from the ammonia gas injector 114 (e.g., to the intake manifold 104, into the cylinder via direct injection).

[0052] In some implementations, the fuel supply 130 may be a high pressure fuel supply. For example, the fuel supply may be configured to supply pressurized gaseous ammonia, hydrogen, methane, or other suitable flammable gas. In another example, the fuel supply may be configured to supply liquefied ammonia, hydrogen, methane, or other suitable flammable gas that may be stored and / or supplied in liquefied form.

[0053] An exhaust after-treatment system 150 (e.g., a catalytic converter) is coupled to exhaust manifolds 106a and 106b and configured to reduce the amount of regulated emissions exiting exhaust pipe 160. An example of an exhaust after-treatment system is further described in the description of FIG.

[0054] Lean fuel-air mixtures are used in many of today's internal combustion engines to reduce regulated emissions, and recent cuts in emissions regulations have pushed NOx limits to the lower end of 1, 1 / 2, 1 / 4, and 1 / 8 TA Luft (where 1 TA Luft is 1.0 gm / kw-hr of NOx emissions). As fuel quality and atmospheric conditions change, engine controllers can have difficulty maintaining the proper air / fuel ratio (AFR is richer than necessary). Additionally, fuel injectors are subject to wear, eventually resulting in inconsistent operating performance.

[0055] Currently, combustion monitoring via cylinder pressure is used in almost all engines in research and development environments to develop engine combustion strategies and their control. However, cylinder pressure-based monitoring systems in production engines are underdeveloped and underpowered due to the slow processors typically available in current production ECUs. They are expensive and unreliable, limiting their applicability to only the most power-dense and most efficient applications where the benefits may justify the cost. With the emergence of new capable ECUs and improved reliability of pressure sensors, widespread use of pressure sensing is expected to be on the horizon. However, even if ECU capabilities and sensor reliability reach their goals, "efficient and meaningful algorithms" remain necessary. In this disclosure, one example of such an efficient and meaningful algorithm is the ability to control fuel delivery and combustion to control and ultimately reduce or eliminate exhaust emissions of NOx and NH3. Some exemplary methods described herein can control combustion by sampling cylinder pressure during each combustion event and delivering certain precisely timed fuel pulses accordingly. In this embodiment, the sensing information is immediately forwarded to the ECU and corrective action is taken.

[0056] Some of the concepts described herein include controlling an engine using in-cylinder pressure measurements processed by an engine control unit (ECU). The concepts disclosed herein may provide the ability to control combustion and / or emissions without the need for a high-powered processor, and in certain examples, without the need for a separate high-powered ECU to process pressure signals into combustion metrics, such as heat release derived parameters, separate from the ECU for determining and controlling ignition timing and fueling. Using in-cylinder pressure measurements may, in some cases, eliminate the need to use multiple other sensors for engine control. For example, mass airflow sensors, NOx (oxides of nitrogen) sensors, knock sensors, or exhaust temperature sensors may be eliminated. Additionally, in certain examples, the concepts herein may be better able to accommodate variations in fuel quality (e.g., variations in energy content (MBTU / m3)).

[0057] The ECU, in a particular example, has the capability to process high speed cylinder pressure data with 0.25° crank resolution and has an embedded processor that can generate a comprehensive set of diagnostics to monitor cylinder pressure as well as filter and average the combustion diagnostics in real time, i.e., simultaneously with engine operation, with sufficient current for use in a control loop to control the engine. In some cases, the processing and control is done within a single cycle for each cylinder. In some cases, the ECU can process up to 20 cylinders in real time with a total processing time for each cylinder of about 2.5 milliseconds. Real-time combustion metrics calculated by the ECU include the location of peak pressure (Ploc) and maximum pressure (Pmax) at crank angle or time, pressure at a particular fixed crank angle or volume in one or more cylinders, etc.

[0058] Conventional on-board pressure monitoring systems can be found in the closed loop control of modern 4-cylinder reciprocating diesel engines in both conventional natural gas-diesel dual fuel mode and reaction controlled compression ignition (or RCCI), gas-diesel mode in laboratory environments. However, these concepts are not general and do not translate well to other engine configurations such as engines with fewer or more cylinders, different fuel types, and non-reciprocating engines. The concepts disclosed herein go beyond the laboratory environment and are implemented in an on-board ECU.

[0059] In accordance with the concepts herein, combustion can be controlled on a cylinder by cylinder and engine cycle basis by monitoring engine cylinder pressure and engine shaft position (e.g., by crank angle sensor and / or otherwise), smoothing and averaging the pressure in the cylinder at positions before and after the ignition event that represent equal combustion chamber volumes (e.g., positions on the same cylinder before and after top dead center), and comparing the averaged before and after pressure difference to a predetermined threshold from a particular measured volume that indicates negative combustion quality. In some cases, the cylinder pressure measured at the compression and / or combustion stroke can be used by the ECU to modify fuel timing and amount of fuel delivery at a subsequent (e.g., next cycle) compression and / or combustion stroke.

[0060] In some implementations, the sensed pressures are processed with vector central average smoothing before being used in an algorithm to identify poor combustion events. According to embodiments herein, the algorithms compare exhaust stroke pressure to compression stroke pressure at the same cylinder volume (see PV diagram), typically, but not necessarily, an equal volume condition can be characterized as equal absolute values ​​of engine crank angle relative to TDC (e.g., smoothed pressure at 90° after TDC on the exhaust stroke compared to 90° before TDC on the compression stroke, and / or otherwise).

[0061] According to embodiments herein, a calculation of the pressure difference between the expansion stroke and the compression stroke is input into an algorithm used to determine whether each combustion event is "good" or "bad."

[0062] Some aspects of the embodiments herein include a method using continuous monitoring of cylinder pressure for each cylinder. The method compares the pressure of the combustion stroke to the pressure of the compression stroke at the same engine crank angle. Aspects of the embodiments herein include a method of selecting 1-5 key crank angles for comparison. In some cases, the key crank angles are preset and in some cases, the key crank angles vary during operation. Aspects of the embodiments herein include using appropriate smoothing and averaging of the pressure signal to reduce the effect of noise on the pressure trace. Aspects of the embodiments herein include triggering an alarm condition signal when a poor combustion event is detected by the ECU that can be utilized by the main ECU or main engine control algorithms to shut off the fuel and ignition combustion to protect the engine and avoid engine ignition exhaust explosion.

[0063] In some cases, the concepts herein include a dual fuel diesel-ammonia gas engine that uses cylinder pressure monitoring to determine IMEP and center of combustion gravity (CA50) as the primary method based on novel features such as heat release, while also monitoring and controlling more traditional pressure-only methods such as peak pressure magnitude and location, adjusting ignition and fuel delivery to balance the cylinder while keeping the peak pressure safely below the engine design limits. One such in-cylinder pressure measurement and combustion metrics calculation system is disclosed in U.S. Application No. 15 / 099,486 entitled "Combustion Pressure Feedback Based Engine Control with Variable Resolution Sampling Window." Combustion parameters such as start of combustion location (SOC or CA10), center of combustion (CA50), rate of pressure rise (RPR), and maintaining Pmax below engine limits can be provided to the engine controller and then controlled.

[0064] In conventional ECU systems, in some cases, memory or processor limitations may limit analysis of pressure traces to information customized to directly align with engine control strategies, and the processor for identifying combustion metrics is integrated into the same device as the remainder of the engine control unit. In memory or processor limited implementations, conventional ECU systems may select a small subset of combustion metrics and use surrogate analysis that serves only one type of pre-designed engine control objective, but this is uncommon.

[0065] In some examples of the present ECU system, the system converts high speed cylinder pressure data into meaningful low speed data, notifies the user of engine operating conditions (such as full or poor combustion) within a small number of engine cycles, even within a single cycle, and provides a stable and reliable smart sensor input to the ECU to achieve the following benefits: In some cases, the pressure data provided to the ECU system also enables engine protection via appropriate actuator modifications, providing overpressure (Pmax) protection, rate of pressure rise (RPR) protection, and knock detection. In some cases, the ECU system calculates combustion quality metrics and identifies modifications to the above actuators (e.g., ignition timing, in-cylinder and port injection timing and duration, AFR control, throttle position).

[0066] In some instances, an on-board controller is incorporated into the system that communicates with the main controller directly or via a controller area network (CAN) link without significant time delay. Alternatively, in some cases, one or more of the combustion quality detection methods described above may be executed directly on the main processor of the ECU, assuming adequate computing power is available.

[0067] In some cases, the engine control system is configured to improve knock margins in ammonia engines, improve maximum displacement of ammonia to diesel fuel in ammonia-diesel dual fuel applications, and precisely control combustion phasing for low temperature combustion (LTC) strategies such as homogenous charge compression ignition (HCCI), reactivity controlled compression ignition (RCCI), and homogenous charge compression ignition (PCCI), improving efficiency with equal emissions or engine reliability within all engine protection limits.

[0068] Referring first to FIG. 2, an example of the present system is shown as an engine system 200. In some implementations, the engine system 200 can be an example of the engine system 100 of FIG. 1. The engine system 200 includes an engine control unit 202, an air / fuel module 204, an ignition module 206, and an engine (shown here as a reciprocating engine) 201. FIG. 2 shows, for example, an internal combustion engine 200. For purposes of this disclosure, the engine system 200 is described as a gas-fueled reciprocating piston engine. In a particular example, the engine runs on ammonia fuel. The engine may be any other type of combustion engine, both in terms of fuel type (gas (e.g., ammonia, natural gas, hydrogen), liquid (e.g., gasoline, diesel fuel, and / or other), single-phase or mixed-phase multi-fuel, and / or other configurations), and the physical configuration of the engine (e.g., reciprocating, Wankel rotary, and / or other configurations). Although the engine control unit 202, air / fuel module 204, and ignition module 206 are shown separately, the modules 202, 204, 206 may be combined into a single module or may be part of an engine controller having other inputs and outputs.

[0069] The reciprocating engine 201 includes an engine cylinder 208, a piston 210, an intake valve 212, and an exhaust valve 214. The engine 201 includes an engine block that includes one or more cylinders 208 (only one is shown in FIG. 2). The engine 200 includes a combustion chamber 260 formed by the cylinder 208, the piston 210, and a head 230. The ignition device 220 is positioned within the head 230, allowing the ignition device 220 access to the combustible mixture. In general, the term "ignition device" can refer to a direct fuel injector in a pre-chamber and / or a spark plug or other ignition device. In the case of a spark plug, a spark gap 222 of the spark plug 220 is positioned within the combustion chamber 260. Other types of ignition devices can be used, such as compression ignition, laser igniters, hot surface igniters, and / or other types of igniters. A piston 210 in each cylinder 208 is movable between a top dead center (TDC) position and a bottom dead center (BDC) position to compress a charge of combustible mixture as a gas or a gas / liquid mixture during a compression phase and from a top dead center position by expanding the combustion gases during an expansion phase. The engine 200 includes a crankshaft 240 that couples each piston 210 such that the piston 208 in each cylinder 208 moves between the TDC position and the BDC position to rotate the crankshaft 240. The TDC position is the position of the piston 210 where the combustion chamber 260 has the smallest volume (i.e., the piston 210 is closest to the spark plug 220 and the top of the combustion chamber 260) and the BDC position is the position of the piston 210 where the combustion chamber 260 has the largest volume (i.e., the piston 210 is furthest from the ignition device 220 and the top of the combustion chamber 260).

[0070] The cylinder head 230 defines an intake passage 231 and an exhaust passage 232. The intake passage 231 channels air or an air-fuel mixture from the intake manifold 216 to the combustion chamber 260. The exhaust passage 232 channels exhaust gases from the combustion chamber 260 to the exhaust manifold 218. The intake manifold 216 communicates with the cylinders 208 via the intake passage 231 and the intake valve 212. The exhaust manifold 218 receives exhaust gases from the cylinders 208 via the exhaust valve 214 and the exhaust passage 232. The intake valves 212 and exhaust valves 214 are controlled via a valve actuation assembly for each cylinder, which may be electronically, mechanically, hydraulically or pneumatically controlled, or via a camshaft (not shown).

[0071] Movement of the piston 210 between the TDC and BDC positions in each cylinder 208 defines an intake stroke, a compression stroke, a combustion or power stroke, and an exhaust stroke. The intake stroke is the movement of the piston 210 away from the ignition device 220 with the intake valve 212 open, drawing a fuel / air mixture into the combustion chamber 260 via the intake passage 231. The compression stroke is the movement of the piston 210 towards the ignition device 220 with the air / fuel mixture entering the combustion chamber 260, with both the intake valve 212 and exhaust valve 214 closed, allowing movement of the piston 210 to compress the fuel / air mixture in the combustion chamber 260. The combustion or power stroke is the movement of the piston 210 away from the ignition device 220, which occurs after the combustion stroke, in which the combustible air / fuel mixture is ignited. The ignited fuel / air mixture burns, rapidly increasing the pressure in the combustion chamber 260 and exerting an expansion force on the movement of the piston 210 away from the ignition device 220. The exhaust stroke is the movement of the piston 210 towards the ignition device 220 after the combustion stroke, opening the exhaust valve 214 and allowing the piston 210 to expel the burned gases through the exhaust passage 218 and into the exhaust manifold 218.

[0072] Engine 200 includes a fuel supply 224, such as a fuel injector, gas mixer, or other fuel supply, to direct ammonia fuel to intake manifold 216 or directly to combustion chamber 260. In some cases, engine system 200 may include another type of internal combustion engine 201 without pistons / cylinders, such as a Wankel engine (i.e., an engine with a rotor within the combustion chamber).

[0073] During engine operation, i.e., during a combustion event in the combustion chamber 260, the air / fuel module 204 supplies ammonia fuel to the flow of air entering the intake manifold before entering the combustion chamber 260. The ignition module 206 controls the ignition of the air / fuel in the combustion chamber 260 by timing the injection of diesel fuel into the combustion chamber 260, thereby initiating the combustion of the fuel / air mixture in the combustion chamber 260 during a series of ignition events between each successive compression and combustion stroke of the piston 210. During each ignition event, the ignition module 206 controls the ignition timing and provides power to the ignition device 220. The air / fuel module 204 can control the fuel injectors 224 and control the throttle valve 226 to supply air and fuel to the engine cylinders 208 in a target ratio. The air / fuel module 204 receives feedback from the engine control module 202 and adjusts the air / fuel ratio. The ignition module 206 controls the ignition device 220 by controlling the flow of current from a power source (e.g., alternator, battery). The ECU 202 regulates the operation of the ignition module 206 based on engine speed and load, in addition to aspects of the system disclosed below.

[0074] In some cases, the ECU 202 includes the ignition module 206 and the fuel / air module 204 as an integrated software algorithm executed by a processor of the ECU 202 to operate the engine as a single hardware module in response to inputs received from one or more sensors (not shown) that may be located throughout the engine. In some cases, the ECU 202 includes separate software algorithms corresponding to the described operation of the fuel / air module 204 and the ignition module 206. In some cases, the ECU 202 includes individual hardware modules that help achieve or control the described functions of the fuel / air module 204 and the ignition module 206. For example, the ignition module 206 of the ECU 202 may include an ASIC for regulating the current supply to the ignition device 220. There are multiple sensor systems for monitoring the operating parameters of the engine 200, including, for example, a crankshaft sensor, an engine speed sensor, an engine load sensor, an intake manifold pressure sensor, an in-cylinder pressure sensor, and the like. Generally, these sensors generate signals in response to the operating parameters of the engine. For example, crankshaft sensor 271 reads and generates a signal indicative of the angular position of crankshaft 240. In an exemplary implementation, high-speed pressure sensor 272 measures cylinder pressure during engine 200 operation. Sensors 271, 272 may be directly connected to ECU 202 to facilitate sensing, or in some cases may be integrated with a Real-Time Combustion Diagnostics and Control (RT-CDC) unit configured to obtain high-speed data from one or more sensors and provide low-speed data output to ECU 202. In some cases, the ignition control described herein is a standalone ignition control system that provides operation of ECU 202 and ignition module 206. The sensors may be integrated into ECU 202 or one of the control modules, such as RT-CDC. Other sensors are possible, and the systems described herein may include multiple sensors to facilitate sensing of the engine operating parameters listed above.

[0075] 3 is an enlarged cross-sectional view of a cylinder 308 of an internal combustion engine 301. In some implementations, the engine 301 can be a modification of the engine 201 illustrated in FIG.

[0076] Engine 301 includes an engine cylinder 308, a piston 310, an intake valve 312, and an exhaust valve 314. Engine 301 includes an engine block that includes one or more cylinders 308 (only one is shown in FIG. 3). Engine 301 includes a combustion chamber 360 formed by cylinder 302, piston 310, and head 330.

[0077] Port fuel injectors (not shown) supply ammonia gas fuel to intake plenum 313 upstream from cylinders 308. Direct fuel injectors 320 are positioned in head 330 and supply diesel fuel for combustion. In some implementations, direct fuel injectors 320 may also include direct injectors of ammonia fuel, such as when direct injection is used instead of port injection. A piston 310 in each cylinder 308 moves between a top dead center (TDC) position and a bottom dead center (BDC) position. The pistons 308 move between the TDC and BDC positions in each cylinder 308 to rotate a crankshaft. The TDC position is the position of the piston 310 where the combustion chamber 360 has its smallest volume (i.e., the position where the piston 310 is closest to the direct fuel injector 320 and the top of the combustion chamber 360), and the BDC position is the position of the piston 310 where the combustion chamber 360 has its largest volume (i.e., the position where the piston 310 is farthest from the spark plug 320 and the top of the combustion chamber 360).

[0078] The piston 310 has a face 390. A piston bowl 392 having a predetermined shape is defined in the piston 310 and opens at the face 390. A shoulder 394 is defined at the interface of the piston face 390 and the piston bowl 392. A crevice 396 is defined between the piston 310 and the cylinder 308.

[0079] The direct fuel injector 320 is configured to spray a conical jet 380 of fuel (e.g., diesel) into the combustion chamber 360. The direct fuel injector 320 is configured to distribute the conical jet 380 at an angle 382 of about 50° to about 70°. This differs from conventional spray patterns that typically have a distribution angle of 120° to 140°. In some implementations, the direct fuel injector 320 may include one or more nozzles (e.g., 4-8 individual nozzles) configured to spray the diesel fuel into the combustion chamber 360. In some implementations, the conical jet 380 may be provided by multiple injector nozzles, with each of the multiple nozzles configured to spray a portion of the conical jet 380.

[0080] The conical jet 380 is configured to direct fuel toward the shoulder 394 when the piston is in position during the compression stroke. In some implementations, fuel impingement on the shoulder 394 may improve diesel particle distribution. For example, diesel particles in the gap region may help burn ammonia in the gap region and reduce ammonia slip (e.g., by combustion initiation starting from diesel vapors from vaporized diesel droplets in the gap region). In another example, diesel particles in the piston bowl 392 may help improve combustion rate, for example, by adding highly reactive diesel vapors to a less reactive ammonia-air mixture. In another example, the injection time and angle 382 may be configured to bring the resulting air / fuel mixture closer to a mixture auto-ignition condition at the TDC position. In another example, auto-ignition may be controlled by injection time. Early injection may vaporize diesel droplets to mix with ammonia, and late injection may provide a more stratified lambda. During compression, diesel droplets evaporate and the vapor mixes with the air to provide a spectrum of air-fuel mixtures (e.g., lambda distribution) where the zone most likely to ignite is close to stoichiometric (e.g., lambda 1.0) and surrounded by other regions that are too rich or too lean. If early injection is used, the majority will be well mixed and thus lean, while later injection will result in more zones that are not well mixed (e.g., stratified) and auto-ignition is more likely to occur. In another example, the spark and angle 382 can be configured to allow the engine 301 to run at a high compression ratio and high efficiency.

[0081] 4 illustrates an example cylinder stroke chart 400. Chart 400 shows a line 410 that represents an example combustion chamber pressure versus crank angle for an engine configured with direct injection of ammonia fuel and diesel fuel. In some implementations, chart 400 may represent an example cylinder pressure for an example engine system 100 of FIG. 1, an example engine system 200 of FIG. 2, or an example engine 301 of FIG. 3.

[0082] At approximately -360° crank angle before top dead center (TDC), exhaust valve closing (EVC) 420 occurs and the intake stroke 422 begins. As air is drawn into the cylinder, pressure 410 remains low. At approximately -320° crank angle, ammonia injection 424 begins. Bottom dead center (BDC) 426 occurs at -180°, ending the intake stroke 422 and beginning the compression stroke 440. Intake valve closing (IVC) also occurs near BDC, essentially sealing off the compression chamber.

[0083] As the compression stroke 440 begins, the pressure 410 slowly begins to rise. At a predetermined crank angle (e.g., about -70° in the illustrated example), a first pulse 442 of diesel fuel is injected into the combustion chamber to prepare an air / fuel mixture that is close to auto-ignition. In some implementations, the timing and / or placement of the first pulse 442 can be based on variable inputs such as pressure 410 (e.g., measured by fast pressure sensor 272 in the cylinder), measured air pressure / density, measured air temperature, fuel parameters, or combinations thereof, and / or other suitable variables or parameters that may affect combustion. In some implementations, the predetermined crank angle can be based on engine operating parameters, such as engine load, engine speed, or combinations thereof, and other suitable operating conditions.

[0084] As the compression stroke 440 continues, the pressure 410 continues to rise. At a given crank angle (e.g., approximately −8° in the illustrated example, and / or may be a function of engine load and / or speed), a second pulse 444 of diesel fuel is injected into the combustion chamber to initiate combustion and control the CA50 (e.g., the crank angle at which 50% of combustion has occurred), CA10 (e.g., the start of combustion), and / or NH3 / NOx ratio of the combustion cycle. In some implementations, the timing and / or placement of the second pulse 444 can be based on variable inputs such as pressure 410 (e.g., measured by the example high speed pressure sensor 272), measured air pressure / density, measured air temperature, fuel parameters, and combinations thereof, and / or other suitable variables or parameters that may affect combustion. Depending on the implementation, changing the combustion phasing (e.g., characterized by either CA10 or CA50) may change the NH3 / NOx ratio exiting the engine. In some implementations, such functionality may be implemented using a feedback mechanism that monitors NOx or NH3 exiting the catalyst and adjusts combustion phasing accordingly to achieve target ratios.

[0085] The compression stroke 440 ends at TDC 450 (e.g., 0°). In some implementations, selective catalytic reduction (SCR) can be used to reduce NH3 so that the NH3 / NOx ratio can be maintained slightly above 1 (e.g., >1 (plus or minus about 0.3), from about 1 to about 1.2).

[0086] In some implementations, the predetermined crank angle may be based on engine operating parameters, such as engine load, engine speed, or a combination thereof, and other suitable operating conditions. In some implementations, the crank angle, fueling settings, and cylinder pressures used and identified in a combustion cycle may be processed to modify the crank angle and fueling settings used in a subsequent (e.g., next) combustion cycle.

[0087] 5 illustrates an example cylinder stroke chart 500. Chart 500 shows a line 510 that represents an example combustion chamber pressure versus crank angle for an engine configured with port injection of ammonia gas fuel. In some implementations, chart 500 may represent example cylinder pressure for example engine system 100 of FIG. 1, example engine system 200 of FIG. 2, or example engine 301 of FIG. 3.

[0088] At approximately -360° crank angle before TDC, exhaust valve closing (EVC) 520 occurs and the intake stroke 522 begins. As air is drawn into the cylinder, pressure 510 remains low. At approximately -320° crank angle, ammonia injection 524 begins. BDC 526 occurs at -180°, ending the intake stroke 522 and beginning the compression stroke 540. IVC also occurs near BDC, essentially sealing off the compression chamber.

[0089] As the compression stroke 540 begins, the pressure 510 slowly begins to rise. At a predetermined crank angle (e.g., about -70° in the illustrated example), a first pulse 542 of diesel fuel is injected into the combustion chamber to prepare an air / fuel mixture that is close to auto-ignition. In some implementations, the timing and / or placement of the first pulse 542 can be based on variable inputs such as (e.g., pressure 510 measured by fast pressure sensor 272), measured air pressure / density, measured air temperature, fuel parameters, and combinations thereof, and / or other suitable variables or parameters that may affect combustion. In some implementations, the predetermined crank angle can be based on engine operating parameters such as engine load, engine speed, or combinations thereof, and other suitable operating conditions.

[0090] As the compression stroke 540 continues, the pressure 510 continues to rise. At a predetermined crank angle (e.g., approximately −8° in the illustrated example, and / or which may be a function of engine load and / or speed), a second pulse 544 of diesel fuel is injected into the combustion chamber to initiate combustion and control the CA50 and NH3 / NOx ratio of the combustion cycle. In some implementations, the timing and / or placement of the second pulse 544 may be based on variable inputs, such as the pressure 510 (e.g., measured by the high speed pressure sensor 272), measured air pressure / density, measured air temperature, fuel parameters, and combinations thereof, and / or other suitable variables or parameters that may affect combustion.

[0091] The compression stroke 540 ends at TDC 550 (e.g., 0°). In some implementations, selective catalytic reduction (SCR) can be used to reduce NH3 so that the NH3 / NOx ratio can be maintained slightly above 1 (e.g., >1, about 1 to about 1.2).

[0092] In some implementations, the predetermined crank angle may be based on engine operating parameters, such as engine load, engine speed, or a combination thereof, and other suitable operating conditions. In some implementations, the crank angle, fueling settings, and cylinder pressures used and identified in a combustion cycle may be processed to modify the crank angle and fueling settings used in a subsequent (e.g., next) combustion cycle.

[0093] FIG. 6 is a schematic diagram of an example of an engine control system 600. In some implementations, the engine control system 600 may be all or part of an example of the engine control system 202 of FIG. 2. FIG. 6 shows an ECU 602 in the engine control system 600 configured to control an engine 601. As described above, high speed pressure data 672 is generated by pressure sensors 672, each mounted with direct access to the combustion chamber. Pressure signals 673 are captured at a high crank synchronous rate, for example, with a resolution of 0.25° or 2880 samples per cycle of the engine 601. In some implementations, this composite crank angle signal can be generated from a lower resolution crank position signal. For example, in a typical crank angle encoder 671 that generates a crank angle signal 615 by sensing the passage of a tooth edge on a disk, the disk is mounted to rotate with the crank, and the crank position resolution is based on the number of teeth. A typical 60-2 tooth wheel has a resolution of 6°. However, in some cases, interpolation can be used to identify the crank angle in the space between the edges. In this way, the spacing between edges can be the previously observed tooth period divided by the number of edges required to achieve the desired angular sampling resolution, and the encoder system can be resynchronized at each edge to account for slight variations between crank teeth that may be observed even at a constant average engine speed.

[0094] In some cases, the resulting high resolution pressure signal 673 can be used by the ECU 602 combustion analysis routines to generate combustion analysis 619, e.g., IMEP, Pmax, CA50, NOx emissions, NH3 emissions, and combustion quality (e.g., good combustion, poor combustion, misfire) on a cylinder-by-cylinder, cycle-by-cycle basis. The metrics 619 are then used by the ECU 102 as feedback signals to adjust key combustion performance characteristics by adjusting engine control actuator settings 619. In an exemplary embodiment, the crank angle signal 615 is used to analyze the pressure signal 673 at crank angles before and after TDC (e.g., two equal main combustion chamber volumes) during each combustion event to determine whether a combustion event in the main combustion chamber of the engine 601 indicates poor combustion or misfire based on a comparison of the difference between the two pressure signals to a threshold value associated with the sampled crank angle or range of crank angles.

[0095] In conventional (non-LTC) dual fuel operation, combustion phasing is a critical factor for efficiency, emissions, and knock margins. Good control of combustion phasing can significantly improve maximum gas displacement rates. Because not all variables in an engine (e.g., Manifold Absolute Temperature (MAT), Manifold Absolute Pressure (MAP), and injection rail pressure) can be maintained within tight tolerances, the typical open-loop method of controlling combustion phasing can be significantly enhanced with some feedback mechanism.

[0096] Reactivity Controlled Compression Ignition (RCCI) is one of many LTC strategies to dramatically reduce NOx formation and simultaneously achieve rapid combustion of lean mixtures to improve efficiency. In RCCI, two fuels of different reactivity are introduced early into the combustion chamber to adjust the phasing and burn rate of combustion. In gas-diesel RCCI, natural gas is injected into the intake port and diesel fuel is injected directly into the combustion chamber. With a diesel common rail, it is possible to inject diesel fuel at various times and amounts up to the limits of the injection system. Typically, diesel fuel is injected much earlier than normal diesel or gas-diesel dual fuel, from just after intake valve closure (IVC) to 70° before top dead center (BTDC, where TDC is the crank position where the piston is at its highest point in the cylinder). Additionally, the sign of the "gain" switch is reversed in RCCI to diesel and dual fuel combustion, where earlier diesel fuel timing results in later combustion phasing and earlier diesel fuel timing results in earlier combustion phasing.

[0097] 7 is a schematic half-sectional view of an example gas mixer 700. In some implementations, the gas mixer 700 may be an example of the ammonia gas injector 114 of FIG. 1. The gas mixer 700 includes a gas housing 702 that defines a mixing chamber 704 having an air flow passage 705. The mixing chamber 704 is configured as a converging-diverging nozzle 706 having a converging conical portion 708a where the air flow passage 705 contracts and a diverging conical portion 708b where the air flow passage 705 expands to an outlet 710. In some implementations, the outlet 710 may be fluidly coupled to an intake manifold, such as an example of the intake manifold 104 of FIG. 1.

[0098] The gas mixer 700 includes an air inlet 712 to the converging-diverging nozzle 706. In some implementations, the air inlet 712 can be fluidly coupled to an intake plenum, such as the example intake plenum 103 of FIG. 1. The conical converging portion 708a defines an air nozzle for the incoming air flow. In general, air flows along the air flow path 705 through the air inlet 712 upstream of the converging-diverging nozzle 706, converges into the conical converging portion 708a, expands at the conical diverging portion 708b, and exits through the outlet 710. The conical converging portion 708a converges in the direction of flow toward the converging end. That is, the downstream end (outlet) of the conical converging portion 708a has a smaller cross-sectional area (e.g., smaller flow area) than the upstream end (air inlet 712). Conical diverging portion 708b diverges in the direction of flow toward a diverging end proximal to outlet 710. That is, the downstream end of conical diverging portion 708b (outlet 710) has a larger cross-sectional area (e.g., smaller flow area) than the upstream end.

[0099] The narrowing of the conical converging section 708a increases the flow velocity of the airflow as it passes along the airflow passage 705. At the conical diverging section 708b, the cross-sectional area of ​​the flow passage increases along the airflow passage 705. The increase in cross-sectional area slows the flow velocity and increases the pressure of the fluid flow. In certain examples, the increase in cross-sectional area can be sized to increase the pressure within the gas mixer 700 such that there is no, only a small, or otherwise small pressure drop across the gas mixer 700. In some implementations, the converging-diverging nozzle 706 can include threads or another form of removable attachment (e.g., a hose clamped around a flange) at the inlet 712, the outlet 710, or both, which attaches to and fluidly couples with the remainder of the intake of the engine system 100. Similarly, in some implementations, the conical converging portion 708a and the conical diverging portion 708b may be modularly interchangeable with each other and / or with gas nozzles 730 of different shapes and configurations to allow the system to be easily modified to suit multiple engine applications.

[0100] The gas mixer 700 includes a gas nozzle 720 and a gas inlet 722. The gas inlet 722 is configured to receive a flow of secondary gas (such as EGR gas) and define a secondary gas flow path 726 through the gas nozzle 720. The gas nozzle 720 is configured to be positioned parallel and centrally to the air flow path 705 and to supply secondary gas (e.g., flowing along the secondary gas flow path 726) to the air flow path 705 in the converging portion 708a, upstream from the diverging portion 708b, of the converging-diverging nozzle 706. The gas nozzle is configured to define a flow of secondary gas that is complementary (e.g., cooperative, substantially parallel) to the flow of air along the air flow path 705.

[0101] In some implementations, the gas nozzle 706 is modularly interchangeable with differently shaped gas nozzles 706, allowing the system to be easily modified to accommodate multiple engine applications. For example, the gas nozzle 706 may include threads or another form of removable attachment to the remainder of the gas housing 702. While the illustrated example shows the converging cone portion 708a, the diverging cone portion 708b, and the gas nozzle 706 aligned on the same central axis, in some implementations, these elements may not be aligned or parallel. For example, space constraints may require the gas mixer 700 to have an angle between the axes of the converging cone portion 708a and the diverging cone portion 708b. In some implementations, rather than having a substantially straight flow path as shown in FIG. 7, the flow path may be curved.

[0102] The gas mixer includes a fuel inlet 730 configured to receive fuel (e.g., ammonia) from a fuel supply, such as the exemplary fuel supply 130 of FIG. 1. The fuel inlet 730 is fluidly coupled to a set of fuel inlet tubes 732a and 732b. The fuel inlet tubes 732a and 732b are configured as fuel nozzles that supply fuel into a second flow passage upstream of a convergent nozzle and supply fuel to a secondary gas flow passage 726. The fuel inlet tube 732a is positioned parallel to and centrally located in the second flow passage. The fuel inlet tube is configured to supply fuel to the secondary gas flow passage 726 upstream of the gas nozzle 720. The fuel inlet tube 732b is positioned near an inner circumference of the gas nozzle 720 and configured to supply fuel to the secondary gas flow passage 726 near an outlet of the gas nozzle 720. The fuel inlet tubes 732a and 732b are configured to define a fuel flow that is complementary (e.g., coordinated, substantially parallel) to the flow of secondary gas along the secondary gas flow passage 726. In some implementations, the fuel may be received at high pressure (e.g., liquefied natural gas at 4-12 bar). As the fuel exits the fuel inlet tubes 732a, 732b, the flow of fuel drives the flow of the secondary gas.

[0103] In some implementations, the fuel inlet 730 may be a gas fuel inlet coupled to a source of gas fuel. However, the fuel provided by the fuel inlet 730 includes a combustible fluid, such as natural gas, gasoline, or diesel. While the fuel inlet 730 is shown as a single tube, it may be configured, for example, as a through-pass that intersects the mixer flow field, as fuel supply holes along the perimeter of the flow field, or in another manner. The illustrated example shows the fuel inlet tubes 732a, 732b configured to inject fuel upstream of the diverging portion 708b, but fuel may also be added using fuel supply ports upstream of the air inlet 712 or the secondary gas inlet 722. Such ports may include gas fuel supply ports. In some cases, fuel may be provided at high velocity, up to and including sonic flow velocity, at the exit of the fuel inlet tubes 732a, 732b such that a fuel-gas jet pump is created, and the fuel may provide additional momentum to the secondary gas flow 726 entering and passing through the nozzle 720. In such instances, the higher pressure can produce a sonic jet that can further enhance the fuel-air mixture. Depending on the implementation, this may reduce the need for a fuel pressure regulator. Additionally, if the fuel jet cools due to the Joule-Thomson effect, this cooling effect can cool the air / fuel flow, thus reducing the size and / or need for intake cooling (e.g., intercooler 120).

[0104] In some implementations, the fuel inlet 730 may be a high pressure fuel inlet. For example, to help accelerate the airflow, high pressure gaseous fuel (e.g., NH3, H2, or methanol or other low carbon fuels at gas pressures of 10 to 500 bar) may be fed through the fuel inlet tubes 762a, 762b. In another embodiment, liquefied gaseous fuel (e.g., NH3, liquefied natural gas, H2) may be heated under liquid conditions and then fed through the fuel inlet tubes 762a, 762b, where the liquefied gaseous fuel may be injected into the air or EGR stream and "flashed" to form a very high velocity (e.g., sonic) jet, thus increasing the pumping effect.

[0105] Depending on the implementation, the gas mixer 700 can be used in alternative configurations. For example, EGR is not typically used in diesel engine applications. However, other gases, such as ammonia, can be provided as a secondary gas at the gas inlet 722 and combined with the diesel fuel flowing through the fuel inlet tubes 732a, 732b to promote air intake. In a particular example, ammonia can be provided at 50 bar and mixed in the gas mixer 700 to create a stoichiometric mixture (e.g., 15% ammonia and 85% air).

[0106] The gas mixer 700 also includes a check valve 760 with two gas inlets. The check valve 760 includes a gas inlet 762a and a gas inlet 762b. The gas inlet 762a is configured to receive a secondary gas (e.g., EGR) from a first source, such as the exemplary EGR flowpath 108a. The gas inlet 762b is configured to receive a secondary gas (e.g., EGR) from a different second source, such as the exemplary EGR flowpath 108b. In some implementations, the gas inlets 762a, 762b may include threads or another form of removable attachment (e.g., a hose clamped around a flange) on the gas inlets 762a, 762b, the gas inlet 722, or any of these to allow the check valve 760 to be mounted and fluidly coupled to the remainder of the EGR system of the engine system 100.

[0107] In some implementations, the gas mixer 760 can be fluidly coupled to an engine system configured to have a secondary gas (e.g., EGR) flow in pulses alternating between gas inlets 762a and 762b, such as where gas inlet 762a is in fluid communication with a first cylinder and gas inlet 762b is in fluid communication with a different second cylinder, with the first cylinder configured to exhaust and the second cylinder configured not to exhaust, or vice versa.

[0108] Check valve 760 also includes valve 764. Valve 764 is configured as a flapper valve in that gas flow through one of gas inlets 762a and 762b pushes the valve body open against the flowing gas inlet, while a pivot valve blocking the other prevents backflow from gas inlet 762a to gas inlet 762b, and prevents backflow from gas inlet 762b to gas inlet 762a. Valve 764 is a flapper valve in the illustrated example, but other types of backflow prevention valves, such as check valves, can be used.

[0109] The gas nozzle 720 is configured to provide a high velocity gas path. The second gas flow passage 726 is aerodynamically efficient to maintain high velocity (e.g., from the exhaust manifolds 106a, 106b). This allows full total pressure on the secondary gas flow (e.g., static pressure + dynamic pressure due to velocity). The fuel flow through the fuel inlet tubes 732a, 732b adds additional momentum to the secondary gas flow along the secondary gas flow passage 726. The secondary gas (e.g., EGR) and fuel combine together into a combined primary jet, creating an aspiration of air flowing along the air flow passage 705. This is the reverse of a conventional jet pump where air and fuel are combined as a primary flow to induce a secondary (e.g., EGR) gas flow. An advantage of the illustrated example is that the pulsating motion of the secondary gas along the secondary gas flow passage 726 accelerates the intake of air from the air inlet 712. In implementations where the air flow is also pumped at its own high velocity, such as by the example compressor 122 of FIG. 1, the air flow can also provide a complementary drop in suction pressure as seen by the gas path, and both flows can help promote the other flow.

[0110] In some implementations, the gas mixer 700 can improve engine performance. For example, by using the fuel stream and secondary gas stream to accelerate, pump, or otherwise enhance the air flow, less compressor work is required from the turbine 122 to move the same amount of air. Reducing the work required by the turbine 122 can reduce the amount of backpressure in the exhaust manifolds 106a, 106b, reducing power losses due to the pumping work done by the piston during the exhaust stroke. The gas mixer 700 allows for the use of higher levels of EGR, up to about 30%. The use of the gas mixer 700 allows the efficiency of a stoichiometric EGR engine to approach a lean engine, while allowing the use of TWC, resulting in near zero emissions.

[0111] In use, the gas nozzle 720 and conical converging section 708a increase velocity and decrease air pressure along the air flow passage 705 in the gas mixer 700. Air is drawn along the air flow passage 705 through the air inlet 712 into the gas mixer 700 in response to (e.g., due to) the pressure drop of the secondary gas jet exiting the gas nozzle 720. Secondary gas is directed along the secondary gas flow passage 726 (e.g., from the exhaust manifolds 106a and 106b) eventually to a point downstream of the conical converging section 708a. The air stream, secondary gas stream, and fuel stream mix to form a combusted mixture. The pressure of the combusted mixture increases and the velocity of the combusted mixture decreases in the conical diverging section 708b.

[0112] 8 illustrates an example chart 800 of gas concentrations resulting from in-cylinder combustion of ammonia. In some implementations, chart 800 may be a chart of gas concentrations resulting from combustion by the example engine system 100 of FIG.

[0113] Chart 800 shows gas concentrations by weight compared to the crank angle of the engine. The illustrated gas concentrations include NH3 (ammonia), represented by line 810, nitric oxide (NO), represented by line 820, and nitrogen dioxide (NO2), represented by line 830. As chart 800 shows, when ammonia is used as a fuel, NH3 levels start at high pre-combustion levels (e.g., 0.001 kg) while NO and NO2 levels are close to zero. At the start of combustion, near -8° TDC in the illustrated example, the level of NH3 begins to decrease as it burns with oxygen, as represented by arrow 850, resulting in a simultaneous increase in the level of NO, a combustion by-product.

[0114] As combustion continues, the available oxygen is depleted, the burn rate slows, and the rate of change of the amounts of NH3 and NO in the cylinder also slows, eventually stabilizing at approximately 0.0003 kg of NO and 0.0008 kg of NH3. These gases, in the resulting concentrations, are eventually released from the cylinder during the exhaust stroke as exhaust gases. The remaining NH3 in the exhaust gases is commonly referred to as "ammonia slip". Both NO and NH3 are generally considered pollutants, and many jurisdictions have regulations that limit the amount of gases that are permitted in tailpipe emissions.

[0115] 9 is a schematic cross-sectional view of an example diesel aftertreatment system 900. In some implementations, exhaust aftertreatment system 900 may be an example of exhaust aftertreatment system 150 of FIG 1. In some implementations, exhaust aftertreatment system 900 may be a catalytic converter system.

[0116] The illustrated exhaust aftertreatment system 900 is configured to receive exhaust 901 from an engine (e.g., gases discharged from an engine cylinder on the exhaust stroke) and reduce the amount of various pollutant gases before exiting as tailpipe exhaust 902. The exhaust 901 from the engine includes gases such as carbon monoxide (CO), hydrocarbons (HC), NOx, particulate matter (PM), carbon dioxide (CO2), water (H2O), diatomaceous nitrogen (N2), etc. The objective of the operation of the exhaust aftertreatment system 900 is to remove substantially all but CO2, H2O, and N2 before exiting as tailpipe exhaust 902.

[0117] The exhaust aftertreatment system 900 includes several treatment sections. A diesel oxidation catalyst (DOC) filter 910 is provided to reduce CO, HC, and PM emissions. For example: 2CO2+O2→2CO2 [HC]+O2→CO2+H2O 2NO2+O2→NO2

[0118] A Catalyzed Soot Filter (CSF) 920 is provided to collect PM and suppress CO emissions during combustion of the collected PM. Cleaning of carbon PM from the SCF 920 (e.g., regeneration of a diesel particulate filter (DPF)) can be performed actively and / or passively. For example: (active)C+O2→CO2 (passive)C+2NO2→CO2+2NO

[0119] The selective catalytic reduction (SCR) filter 930 uses a reducing agent (e.g., ammonia) and a catalyst to create a chemical reaction that converts NOx into nitrogen, water, and small amounts of CO2. For example: 4NH3+4NO+O2→4N2+6H2O 4NH3+2NO+2NO2→4N2+6H2O 8NH3+6NO2→7N2+12H2O

[0120] An ammonia slip catalyst (ASC) filter 940 is provided to convert residual ammonia (e.g., ammonia slip) into nitrogen and water. For example: [NH3]→N2+H2O NOx+NH3→N2+H2O

[0121] In a typical (e.g., non-dual fuel) diesel application, the reductant used in the SCR filter 930 is a high grade urea, commonly known as diesel exhaust stream (DEF), which must be provided to the SCR filter 930. When the DEF is heated by the hot exhaust gases, it vaporizes and breaks down into ammonia and carbon dioxide. The ammonia acts as a reductant to reduce NO and NO2 levels. However, excess ammonia (e.g., ammonia slip) is also typically regulated as a pollutant gas. The excess ammonia provided by the DEF is then reduced by the ASC filter 940. For example: 4NH3+3O2→2N2+6H2O

[0122] Notable in the illustrated example of diesel aftertreatment system 900 is the omission of a urea (e.g., DEF) mixer at location 950. The diesel aftertreatment system 900 is configured without a urea mixer 950 because the ammonia required for the SCR filter 930 can be obtained from the exhaust 901 from the engine. In a dual fuel ammonia-diesel engine, such as the example of engine system 100 in FIG. 1, the use of ammonia as a fuel can inherently leave ammonia slip in the exhaust gas, as previously discussed in the description of FIG. 8. Such inherent ammonia slip can be used as some or all of the reductant required for the SCR filter 930, reducing or eliminating the need for a DEF and / or urea mixer in the diesel aftertreatment system 900. Excess ammonia remaining after processing by the SCR filter 930 is reduced by the ASC filter 940. The ASC filter is included and appropriately sized to reduce or eliminate NH3 remaining after use in the NOx reaction.

[0123] Additionally, the combustion can be controlled (e.g., by the ECU 202 and / or the air / fuel module 204 illustrated in FIG. 2) to generate a predetermined amount of ammonia slip to allow the SCR to reduce NOx levels below a target amount (e.g., as established by government regulations). For example, in some cases, the amount of ammonia slip in the exhaust 901 from the engine may be insufficient for the full operation of the SCR filter 930. This can result in excess NO and NO2 emissions. In such cases, the mixing and combustion of ammonia and diesel can be purposefully controlled to increase the amount of ammonia slip, if necessary, to provide a sufficient amount of ammonia for use in the SCR filter 930. In other words, the ammonia fuel can be used as a reductant in the catalytic process, reducing or eliminating the need for a DEF and / or urea mixer in the diesel aftertreatment system 900. Excess ammonia remaining after processing by the SCR filter 930 is reduced by the ASC filter 940. The ASC filter can be included and appropriately sized to reduce or eliminate the NH3 remaining after use in the NOx reaction.

[0124] 10 is a chart 1000 illustrating an example of NOx formation from fuel combustion in air (e.g., example NOx in example exhaust 901 from an example engine of FIG. 9 from example engine 201 of FIG. 2). NOx production from combustion is a function of both lambda (e.g., excess air ratio) and temperature. NOx concentration is represented by line 1010 and temperature is represented by line 1020.

[0125] It is possible to directly control NOx levels in at least two ways. For example, lambda can be controlled by controlling the air-fuel ratio (AFR) provided to the combustion process. In another example, combustion phasing can be controlled (e.g. more advanced for more NOx, more retarded for less NOx).

[0126] In the illustrated example, it can be seen that there is a region 1050 where minimum NOx production 1010 occurs when the mixture is rich (e.g., lambda < about 1.0). In a second region 1060, maximum NOx production 1010 is at or near a lambda of about 1.25, where the temperature 1020 is high and there is excess oxygen due to the lean AFR mixture. In a third region 1070, the effect of excess air reduces the effect of temperature faster than the excess O2 effect, exponentially decreasing NOx production from lambdas of about 1.25 and above, and in the region where lambda is greater than about 1.75, lean combustion reduces NOx production 1010 to below stoichiometry.

[0127] In some implementations, control strategies can be implemented to control combustion phasing. For example, example engine system 100 can use in-cylinder pressure sensing, real-time combustion, diagnostic control (such as active combustion control), and air-fuel ratio control to regulate NOx production. In some embodiments, control strategies can be configured to maintain the NH3 to NOx ratio in a high efficiency range for the exhaust aftertreatment system (e.g., lambda is about 1.0 to about 1.2).

[0128] In some implementations, NOx and NH3 sensors can be used at the inlet and / or outlet of the engine exhaust aftertreatment system 900 (e.g., engine exhaust aftertreatment system 900) as controller feedback in a closed-loop control strategy to adjust in-cylinder NOx production to manage the effectiveness of the engine exhaust aftertreatment system. For example, the ECU 202 and / or the air / fuel module 204 can be configured to receive sensor feedback from the engine exhaust aftertreatment system 900 to measure the efficiency and effectiveness of the engine exhaust aftertreatment system 900 and adjust engine operation to reduce NOx production (e.g., about 90% or more) and / or NH3 consumption (e.g., reducing the requirements of the ASC filter 940). In some implementations, the strategy can be configured to control in-cylinder combustion to produce an NH3 to NOx ratio of between about 1.0 and about 1.2, such that both are reduced by the combination of the SCR filter 930 and the ASC filter 940 without the use of a urea doser (e.g., without a DEF system).

[0129] 11 is a flow diagram of an example process 1100 for controlling an internal combustion engine system. The process 1110 is performed in association with an internal combustion engine having a body sealed in a combustion chamber, the body being movable to a center position for compressing gases in a compression phase and from the center position by expanding the combustion gases in an expansion phase. Each position of the body defines a volume of the combustion chamber. Depending on the implementation, the example process 1100 can be performed by a front or portion of the example engine system 100 of FIG. 1 and / or the example engine system 200 of FIG. 2.

[0130] At 1110, a pressure signal is received from a combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of the compression phase, and the received pressure is a first pressure. For example, an example ECU 202 can receive an in-cylinder pressure feedback signal from an example high speed pressure sensor 272 during a first range of crank angles and / or piston positions.

[0131] At 1120, a first pulse of fuel is delivered at a first position of the body during the compression phase based on the received pressure signal. For example, the air / fuel module 204 and / or the ignition module 206 can deliver a first pulse of fuel to the engine cylinder 208 based on pressure feedback from the fast pressure sensor 272. In some implementations, the pressure signal can be received during a previous combustion cycle and used to configure the first pulse during a subsequent (e.g., next) combustion cycle. In some implementations, the pressure signal can be received and used within the same combustion cycle. In some implementations, the first pulse of fuel can be further configured to prepare an air / fuel mixture close to auto-ignition in the combustion chamber. For example, the first pulse of fuel can be configured such that there is an almost insufficient amount of fuel to cause auto-ignition during the compression stroke. In some implementations, the first pulse can be delivered at example points 442 and / or 542 of FIGS. 4 and 5.

[0132] At 1130, a second pulse of fuel is delivered at a second location of the body during the compression phase based on the received pressure signal. For example, the air / fuel module 204 and / or the ignition module 206 can deliver a second pulse of fuel to the engine cylinder 208 based on pressure feedback from the fast pressure sensor 272. In some implementations, the pressure signal can be received during a previous combustion cycle and used to configure the second pulse during a subsequent (e.g., next) combustion cycle. In some implementations, the pressure signal can be received and used within the same combustion cycle. In some implementations, this process can operate by monitoring the previous cycle with pressure sensing and crank angle position (e.g., converted to volume) and looking for key combustion indicators such as "start of combustion" (e.g., CA10 or 10% MFB or 10% of combustion) and center of combustion (e.g., CA50, 50% MFB (mass fraction of combustion)). From the previous cycle, this cycle can be adjusted to control these parameters to target values. Target values ​​can be set by good combustion phasing, safe operation, and / or NH3 to NOx ratio.

[0133] Some implementations of RCCI (e.g., Advanced Low Temperature Combustion - also known as Reactivity Controlled Compression Ignition) can use: (a) a supply of air and a primary fuel (e.g., NH3), (b) compression to a level after the intake valve closes, (c) a secondary fuel (e.g., diesel fuel) is directly injected early in the cycle (e.g., when the temperature is too low to ignite the diesel fuel), (d) further compression occurs, causing the diesel fuel droplets to break up, vaporize, and mix with the primary fuel, (e) further compression reaches the autoignition temperature of the diesel vapors mixed near the stoichiometric range (e.g., lambda ≈ 1.0), and (f) volumetric autoignition occurs, volumetrically igniting the mixture. The heat release spreads through a wave of precursors to autoignition (e.g., rather than a traditional flame front). In some implementations, volumetric ignition can be triggered using a second injection of secondary fuel to assist or anchor the autoignition event (e.g., "ignition-assisted HCCI / RCCI").

[0134] In some implementations, the process 1100 can also include initiating combustion in the combustion chamber based on the second pulse of fuel. For example, the second pulse of fuel can be configured such that an additional amount of fuel triggers auto-ignition during the compression stroke. In some implementations, the second pulse can be provided at points 444 and / or 544 illustrated in FIGS. 4 and 5.

[0135] In some implementations, process 1100 can also include controlling CA50 with at least one of the first pulse of fuel or the second pulse of fuel. For example, ECU 202 can be configured to deliver fuel at a timing and amount that allows 50% of the fuel to be burned by the time the piston reaches a predetermined position or the crank reaches a predetermined crank angle.

[0136] In some implementations, the process 1100 can include using at least one of the first pulse of fuel or the second pulse of fuel to control the NH3 / NOx ratio resulting from the combustion of diesel fuel, ammonia fuel, and air during the expansion phase. For example, as shown in Figures 4, 5, 8, and 10, the timing and amount of the fuel pulses can be selected to control the amount of NOx and NH3 remaining in the exhaust gas from the engine. In some implementations, the NH3 / NOx ratio can be selected to be greater than 1. In some implementations, the NH3 / NOx ratio can be selected to be less than about 1.2.

[0137] In some implementations, the process 1100 can include receiving free ammonia present in the exhaust gas by an exhaust aftertreatment system and catalyzing NOx based on the free ammonia by the exhaust aftertreatment system (e.g., this is common in current SCR (selective catalytic reaction) systems). For example, an example engine system 100 can include an exhaust aftertreatment system 150 for treating the exhaust gas before it exits the exhaust pipe 160. In another example, an example exhaust aftertreatment system 900 of FIG. 9 can be used to catalyze the exhaust gas as it passes from the exhaust 901 from the engine to the exhaust pipe 902.

[0138] In some implementations, the process 1100 can include controlling the amount of free ammonia present in the exhaust gas based on at least one of the first pulse of fuel or the second pulse of fuel. In particular, the center of combustion (CA50) can be adjusted to an advanced phase to increase NOx and reduce NH3 slip, thereby reducing the NH3 / NOx ratio, or the CA50 set point can be retarded to increase the NH3 to NOx ratio. For example, an example ECU 202 can control one or more of the air / diesel fuel ratio, the air / ammonia fuel ratio, the diesel fuel / ammonia ratio, the first pulse fuel amount, the second pulse fuel amount, the timing of the first pulse fuel, and / or the timing of the second pulse fuel to cause a predetermined amount of ammonia slip at the end of combustion. The free ammonia of the ammonia slip can then be used by an example SCR filter 930 to reduce NOx emissions, and the ASC filter 940 can be used to reduce the amount of free ammonia remaining after the catalytic reaction.

[0139] Figure 12 is a schematic diagram of an example of a general computer system 1200. According to one implementation, system 1200 may be used for the operations described in connection with the example method 1100 of Figure 11. For example, system 1200 may be included in any or all of ECU 202, air / fuel module 204, ignition module 206, RT-CDC 611, or ECU 602.

[0140] The system 1200 includes a processor 1210, a memory 1220, a storage device 1230, and an input / output device 1240. Each of these components 1210, 1220, 1230, and 1240 are interconnected using a system bus 1250. The processor 1210 can process instructions for execution within the system 1200. In one implementation, the processor 1210 is a single-threaded processor. In another implementation, the processor 1210 is a multi-threaded processor. The processor 1210 can process instructions stored in the memory 1220 or the storage device 1230 to display graphical information for a user interface on the input / output device 1240.

[0141] The memory 1220 stores information within the system 1200. In one implementation, the memory 1220 is a computer-readable medium. In one implementation, the memory 1220 is a volatile memory unit. In another implementation, the memory 1220 is a non-volatile memory unit.

[0142] The storage device 1230 can provide mass storage for the system 1200. In one implementation, the storage device 1230 is a computer-readable medium. In various different implementations, the storage device 1230 can be a floppy disk device, a hard disk device, an optical disk device, or a tape device.

[0143] The input / output device 1240 provides input / output operations for the system 1200. In one implementation, the input / output device 1240 includes a keyboard and / or a pointing device. In another implementation, the input / output device 1240 includes a display unit for displaying a graphical user interface.

[0144] The described features can be implemented in digital electronic circuitry, computer hardware, firmware, software, or combinations thereof. The apparatus can be implemented in a computer program product tangibly embodied in an information carrier, e.g. a machine-readable storage device, for execution by a programmable processor, the method steps being performed by the programmable processor executing a program of instructions performing the functions of the described implementation by operating on input data and generating output. The described features can be advantageously implemented in one or more computer programs executable on a programmable system including at least one programmable processor coupled to receive data and instructions from a data storage system, at least one input device, and at least one output device, and to transmit data and instructions to the data storage system, at least one input device, and at least one output device. A computer program is a sequence of instructions that can be used, directly or indirectly, by a computer to perform a particular activity or bring about a particular result. Computer programs can be written in any type of programming language, including compiled and interpreted languages, and can be deployed in any form, such as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0145] Processors suitable for executing a program of instructions include, by way of example, both general and special purpose microprocessors, the sole processor or one of multiple processors of any kind of computer. Typically, a processor receives instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memories for storing instructions and data. Typically, a computer includes, or is in operative communication with, one or more mass storage devices for storing data files. Such devices include magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include, by way of example, any of the following forms of non-volatile memory: semiconductor memory devices, such as EPROM, EEPROM, flash memory devices, for example; magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by, or incorporated in, an ASIC (Application Specific Integrated Circuit).

[0146] To provide for interaction with a user, the features can be implemented in a computer that has a display device, such as a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user, and a keyboard and a pointing device, such as a mouse or trackball, by which the user can provide input to the computer.

[0147] This feature may be implemented in a computer system that includes back-end components such as a data server, or in a computer system that includes middleware components such as an application server or an Internet server, or in a computer system that includes a front-end component such as a client computer with a graphical user interface or an Internet browser, or any combination thereof. The components of the system may be connected by any form or medium of digital data communication, such as a communications network. Examples of communications networks include, for example, a LAN, a WAN, and the computers and networks forming the Internet.

[0148] The computer system may include clients and servers. Clients and servers are generally remote from each other and typically interact through a network, such as that illustrated. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

[0149] Although several implementations have been described in detail above, other variations are possible. For example, the logic flows depicted in the figures do not require the particular order or sequential order shown to achieve desirable results. Additionally, other steps may be provided or removed from the described flows, and other components may be added or removed from the described systems. Accordingly, other implementations are within the scope of the following claims.

Claims

1. 1. An apparatus for controlling the operation of an internal combustion engine, the internal combustion engine comprising a body sealed to a combustion chamber, the body being movable to a top dead center position to compress at least one of a gas or a gas / liquid mixture in a compression phase and movable from said top dead center position by expanding combustion gases in an expansion phase, each position of the body defining a volume of the combustion chamber; a processor that receives input from a position sensor configured to sense a position of the body relative to the volume of the combustion chamber and an input from a combustion chamber pressure sensor, the processor comprising: receiving a pressure signal from the combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of the compression phase, the received pressure being a first pressure; providing a first signal configured to deliver a first pulse of fuel at a first location of the body during the compression phase based on the received pressure signal; and providing a second signal configured to provide a second pulse of fuel at a second location of the body during the compression phase based on the received pressure signal. A device for controlling the operation of an internal combustion engine.

2. the first signal is further configured to prepare an air / fuel mixture that is near auto-ignition upon compression.

10. The apparatus of claim 1.

3. the second signal is further configured to initiate combustion in the combustion chamber.

10. The apparatus of claim 1.

4. The second signal is further configured to control at least one of CA50 or CA10.

10. The apparatus of claim 1.

5. The second signal is NH3 produced from the combustion of diesel fuel, ammonia fuel and air. ３ / NOx ratio, 10. The apparatus of claim 1.

6. the ratio is about 1; 6. The apparatus of claim 5.

7. the ratio is less than about 1.2; 7. The apparatus of claim 6.

8. an exhaust aftertreatment system further configured to receive free ammonia present in the exhaust gas and catalyze NOx based on the ammonia; 10. The apparatus of claim 1.

9. 1. A method carried out in connection with an internal combustion engine comprising a body sealed in a combustion chamber, the body being movable to a point position to compress at least one of a gas or a gas / liquid mixture in a compression phase and movable from the point position by expanding combustion gases in an expansion phase, each position of the body defining a volume of the combustion chamber; receiving a pressure signal from a combustion chamber pressure sensor while the volume is in a first range, the first range corresponding to a portion of a compression phase, the received pressure being a first pressure; delivering a first pulse of fuel at a first location of the body during the compression phase based on the received pressure signal; and delivering a second pulse of fuel at a second location of the body during the compression phase based on the received pressure signal. method.

10. the first pulse of fuel is further configured to prepare an air / fuel mixture near auto-ignition.

10. The method of claim 9.

11. and initiating combustion in the combustion chamber based on the second pulse of fuel.

10. The method of claim 9.

12. Further comprising controlling at least one of CA50 or CA10 based on at least one of the first pulse of fuel or the second pulse of fuel.

10. The method of claim 9.

13. NH produced from combustion of diesel fuel, ammonia fuel, and air based on at least one of the first pulse of fuel or the second pulse of fuel. ３ Further comprising controlling the ratio of NOx to CO2.

10. The method of claim 9.

14. the ratio is about 1; The method of claim 13.

15. the ratio is less than about 1.2; 15. The method of claim 14.

16. receiving free ammonia present in the exhaust gas by an exhaust aftertreatment system; catalyzing NOx based on free ammonia with the exhaust aftertreatment system.

10. The method of claim 9.

17. controlling the amount of free ammonia present in the exhaust gas based on at least one of the first pulse of fuel or the second pulse of fuel.

17. The method of claim 16.

Images