Multi-fuel engine system

Abstract

System (100) exhibiting: an internal combustion engine (104) with several cylinders (200) connected to a crankshaft (208); a crankshaft speed sensor; and a control device (110) which is configured to: to measure a half-order torsional vibration of the internal combustion engine (104) based on signals from the crankshaft speed sensor; to determine the amplitude of the half-order torsional vibration; if the amplitude is greater than a threshold amplitude, indicate a misfire in at least one of the several cylinders (200); to determine a coefficient of variation (COV) of the several cylinders (200) based on the measured half-order torsional vibration; and to adjust a fuel injection duration for one or more of the multiple cylinders (200) based on the coefficient of variation (COV).

Description

AREA

[0001] Embodiments of the subject matter disclosed herein relate, for example, to an internal combustion engine, internal combustion engine components and an internal combustion engine system. STATE OF THE ART

[0002] Given its favorable energy content, natural gas can be used as a fuel source for an internal combustion engine. To achieve low fuel consumption and meet power output requirements across a wide range of operating conditions, some internal combustion engines can be designed to run on both natural gas and liquid fuel, such as diesel. In such multi-fuel engines, the mixture of natural gas and intake air can be combusted in the individual cylinders of the engine in response to the injection of liquid fuel. While some operating conditions may benefit from a relatively high ratio of natural gas to liquid fuel (e.g., 90% natural gas or more), the amount of natural gas used in a given engine cycle may be limited by the smallest possible amount of liquid fuel that can be injected by each fuel injector.

[0003] JP 2001-098999 A discloses a multi-cylinder internal combustion engine equipped with a detection device for acquiring a cam pulse signal from a camshaft and a crank pulse signal from a crankshaft. The internal combustion engine has four calculation devices: one for calculating a 0.5th order frequency component of engine speed fluctuations from at least one of the cam pulse and one of the crank pulse signals; one for calculating a fundamental frequency component of engine speed fluctuations corresponding to the number of cylinders in the engine from at least one of the cam pulse and one of the crank pulse signals; one for calculating a misfire constant by dividing the 0.5th order frequency component by the fundamental frequency component; and one for calculating a misfire frequency based on the presence or absence of a misfire.Furthermore, the internal combustion engine has a determining device for determining the presence or absence of misfire for each cycle from the misfire constant.

[0004] US 2014 / 0074380A1 discloses a gas substitution ratio (GSR) control system that varies the natural gas flow to a bi-fuel engine based on the detected diesel flow to maintain a desired GSR without requiring engine load measurement. The GSR is controlled without monitoring the engine load level. An engine is first calibrated to reflect the actual gas and diesel flows, thus providing the correct GSR for all engine loads. The calibration data is then stored, and the diesel flow rate is monitored. The currently detected diesel flow rate is used to determine the required gas flow rate for the correct GSR. The gas flow to the engine is then adjusted to match the required gas flow rate. SHORT DESCRIPTION

[0005] In one embodiment of the invention, a system comprises an internal combustion engine with multiple cylinders connected to a crankshaft, a crankshaft speed sensor, and a control unit. The control unit is designed to measure half-order torsional vibration of the internal combustion engine based on signals from the crankshaft speed sensor, to determine the amplitude of the half-order torsional vibration, and, if the amplitude exceeds a threshold amplitude, to indicate a misfire in at least one of the multiple cylinders. Furthermore, the control unit is designed to determine a coefficient of variation of the multiple cylinders based on the measured half-order torsional vibration and to adjust the fuel injection duration for one or more of the multiple cylinders based on the coefficient of variation.

[0006] In any embodiment of the system, it may be advantageous for the control device to also be configured to determine, on the basis of a phase of the half-order torsional vibration orders, which of the several cylinders is misfiring when a misfire is indicated.

[0007] In any embodiment of the system, it may be advantageous for the control device to also be configured to increase the amount of fuel injected into the misfiring cylinder when a misfire is indicated.

[0008] In any embodiment of the system, it may be advantageous for the internal combustion engine to be configured to operate with at least one first fuel and one second fuel, and wherein the control device for increasing the amount of fuel injected into the misfiring cylinder is configured to increase the amount of fuel injected of the first fuel relative to the second fuel.

[0009] In any embodiment of the system, it may be advantageous for the first fuel to be a liquid fuel and the second fuel to be a gaseous fuel.

[0010] In any embodiment of the system, it may be advantageous for the control device to be configured to determine, for each of the multiple cylinders, a misfire limit for each of the multiple operating points based on an amplitude of one or more torsional vibration orders measured over the multiple operating points.

[0011] In any embodiment of the system, it may be advantageous for the misfire limit for a particular cylinder of the multiple cylinders to include a minimum opening duration for a liquid fuel injector associated with that particular cylinder.

[0012] In any embodiment of the system, it may be advantageous for the control device to be configured to operate each of the multiple cylinders with a predetermined ratio of gaseous fuel to liquid fuel, each predetermined ratio including a maximum amount of gaseous fuel for delivering a required engine power while remaining above a respective misfire limit.

[0013] In any embodiment of the system, it may be advantageous for the control device to also be configured to determine a measure of combustion variation between the multiple cylinders based on the amplitude.

[0014] In any embodiment of the system, it may be advantageous for the control device to also be configured to adjust a fuel injection quantity for one or more cylinders of the internal combustion engine when the degree of combustion variation is greater than a threshold variation.

[0015] In another embodiment of the invention, a system comprises: an internal combustion engine with multiple cylinders, wherein the internal combustion engine is configured to operate with at least one first fuel and a second fuel; multiple fuel injectors for injecting the first fuel into the multiple cylinders; and a control device configured to: when operating in a tuning mode, operate the internal combustion engine with both the first fuel and the second fuel and determine a minimum opening duration that sustains combustion for each of the multiple injectors;and when operating in a second fuel mode, opening the individual injectors for their determined minimum opening duration to initiate combustion, the minimum opening duration for each of the multiple injectors being determined on the basis of a misfire monitoring device which detects a cylinder misfire based on signals from a crankshaft speed sensor.

[0016] In any embodiment of the system, it may be advantageous for the first fuel to be liquid fuel and the second fuel to be gaseous fuel, and wherein the control device is configured to supply a mixture of gaseous fuel and air to the individual cylinders during the second fuel mode.

[0017] In any embodiment of the system, it may be advantageous for the tuning mode to be performed at a specific internal combustion engine speed and / or load, and wherein the second fuel mode includes subsequent internal combustion engine operation at a specific internal combustion engine speed and / or load.

[0018] In any embodiment of the system, it may be advantageous for each minimum opening duration to include the respective minimum opening duration which does not cause a cylinder misfire, and wherein the control device is designed to detect a cylinder misfire with the misfire monitoring device by detecting a half-order torsional vibration of a crankshaft of the internal combustion engine based on the signals from the crankshaft speed sensor.

[0019] In any embodiment of the system, it may be advantageous for a first injector of the multiple fuel injectors to have a first minimum opening duration and for a second injector of the multiple fuel injectors to have a second minimum opening duration that differs from the first minimum opening duration, and wherein a quantity of fuel supplied by the first injector at the first minimum opening duration is equal to a quantity of fuel supplied by the second injector at the second minimum opening duration.

[0020] In yet another embodiment of the invention, a system comprises: an internal combustion engine with multiple cylinders connected to a crankshaft; a crankshaft speed sensor; and a control device configured to: measure a half-order torsional vibration of the internal combustion engine based on signals from the crankshaft speed sensor; determine a coefficient of variation (COV) of the multiple cylinders based on the measured half-order torsional vibration and based on a peak cylinder pressure for each of the multiple cylinders; and adjust a fuel injection duration for one or more of the multiple cylinders based on the coefficient of variation (COV).

[0021] In any embodiment of the system, it may be advantageous for the coefficient of variation (COV) to comprise a standard deviation of a power output from the multiple cylinders divided by a mean power output.

[0022] In the embodiment of the system according to the invention, it is advantageous that the control device is also configured to determine the coefficient of variation (COV) based on a peak cylinder pressure for each of the several cylinders.

[0023] In any embodiment of the system, it may be advantageous for the internal combustion engine to be configured to burn at least one first fuel and one second fuel, and wherein the control device for adjusting the fuel injection duration for one or more of the multiple cylinders is designed to adjust the fuel injection duration of the first fuel in relation to the second fuel.

[0024] In any embodiment of the system, it may be advantageous for the first fuel to be a liquid fuel and for the second fuel to be a gaseous fuel.

[0025] Note that the above brief description is given to provide a simplified overview of a selection of concepts that are described in more detail in the full description. It is not intended to identify important or essential features of the claimed subject matter, the scope of which is defined solely by the claims that follow the description. Furthermore, the claimed subject matter is not limited to implementations that address any of the disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be better understood if one reads the following description of non-restrictive embodiments with reference to the accompanying drawings: Fig. Figure 1 shows a sketch of an embodiment of a vehicle with an internal combustion engine. Fig. Figure 2 shows a sketch of a cylinder of the internal combustion engine of Fig. 1. Fig. Figure 3 shows a sketch of an internal combustion engine system that replaces the internal combustion engine of Fig. 1 includes. Fig. Figure 4 is a simplified diagram illustrating a procedure for tuning multiple cylinders. Fig. 5 - Fig. Figure 7 are flowcharts that illustrate a procedure for operating a misfire monitoring device. Fig. 8 - Fig. Figure 9 shows examples of injector delivery curves. Fig. Figure 10 is a graph showing a half-order amplitude as a function of combustion variation. Fig. 11 - Fig. Figure 14 are graphs showing different parameters in an internal combustion engine operating with either a 2% combustion variation or a 10% combustion variation. DETAILED DESCRIPTION

[0027] The following description concerns various embodiments for tuning each liquid fuel injector of an internal combustion engine to enable operation at the highest possible ratio of gaseous fuel to liquid fuel (also known as the substitution ratio) for each cylinder of the internal combustion engine. The tuning of each liquid fuel injector can be based on the detection of misfires in individual cylinders during the tuning process. A misfire in each cylinder can be detected using a misfire monitoring device that detects torsional vibrations using signals from a crankshaft sensor.

[0028] As explained above, controlling the combustion of a multi-fuel engine with high gaseous fuel utilization (e.g., with low liquid fuel utilization) can be challenging because the liquid fuel injectors may exhibit non-linear delivery behavior. When the liquid fuel supply is reduced to allow for greater gaseous fuel utilization, a standard liquid fuel injector may suddenly decrease its flow by approximately 15% of its maximum injection rate, a phenomenon known as the turndown point. Each injector in a multi-cylinder engine may have its own turndown point. If all injectors are treated equally, the overall gaseous fuel utilization will be determined by the injector that shuts off at the highest fuel delivery rate.If the injectors have a turndown point in the range of 5% to 15%, the internal combustion engine can be limited to a substitution ratio of 85% (e.g. 85% gaseous fuel, 15% liquid fuel).

[0029] According to embodiments disclosed herein, a misfire monitoring device can be initiated which detects poor combustion in individual cylinders while the liquid fuel injection quantity is reduced, and then individually adjusts the lowest possible liquid fuel injection rate for each cylinder to provide stable combustion in each cylinder. The multi-fuel engine can be designed to operate at a very high substitution ratio of the gaseous fuel, for example, with 99% gaseous fuel and 1% liquid fuel, based on energy content. During the tuning process, the combustion engine can start its combustion entirely with liquid fuel and then add gaseous fuel to a level safe for all cylinders, for example, to 80% gaseous fuel. The unevenness of the combustion is measured by the misfire monitoring device.In some examples, the misfire monitoring device may be a torsional vibration order monitoring device that monitors one or more torsional vibration orders, such as half an order. When all cylinders are firing evenly, the half-order level is low. The liquid fuel injection quantity for each cylinder is reduced until its misfire is detected by the half-order monitoring device. Then, the liquid fuel injection quantity is increased to achieve proper combustion in that cylinder. This process is repeated for each cylinder to fine-tune the entire internal combustion engine to the lowest safe level of liquid fuel consumption. Combustion stability is monitored by the half-order detection system, and if any cylinder begins to misfire, the liquid fuel injection rate for that cylinder can be increased.

[0030] The method described herein can be used in various types of internal combustion engines and in various machine-driven systems. Some of these systems may be stationary, while others may be mounted on semi-mobile or mobile platforms. Semi-mobile platforms can be repositioned between operating periods, for example, by being mounted on low-loaders. Mobile platforms include self-propelled vehicles. Such vehicles may include road transport vehicles as well as mining equipment, ships, rail vehicles, and other all-terrain vehicles. For the sake of clarity, a locomotive is taken as an example of a self-propelled rail vehicle and, more generally, as an example of a mobile platform carrying a system incorporating an embodiment of the invention.

[0031] Before further discussing the approach for providing liquid fuel injection tuning in a multi-fuel engine, an example of a platform is presented in which an internal combustion engine for a vehicle, such as a rail vehicle, can be configured. For example, it shows Fig. Figure 1 shows a block diagram of an embodiment of a vehicle system 100, which is shown herein as a rail vehicle 106 (e.g., a locomotive) designed to travel on a rail 102 via multiple wheels 112. As shown, the rail vehicle 106 has an internal combustion engine 104. In other non-limiting examples, the internal combustion engine 104 may be a stationary internal combustion engine, for example, in a power plant application, or an internal combustion engine in a watercraft, or another propulsion system for a vehicle not designed for road traffic.

[0032] The cylinder 104 receives intake air for combustion from an intake duct 114. The intake duct 114 receives ambient air from an air filter 160, which filters air from outside the rail vehicle 106. Exhaust gas resulting from combustion in the internal combustion engine 104 is supplied to an exhaust duct 116. Exhaust gas flows through the exhaust duct 116 and out of an exhaust stack of the rail vehicle 106. In one example, the internal combustion engine 104 is a diesel engine that combusts air and diesel fuel by compression ignition. In other non-limiting embodiments, the internal combustion engine 104 can additionally combust fuel containing gasoline, kerosene, natural gas, biodiesel, or other petroleum distillates of similar density by compression ignition.

[0033] In one embodiment, the rail vehicle 106 is a diesel-electric vehicle. As in Fig. As shown in Figure 1, the internal combustion engine 104 is connected to a power generation system that includes an alternator / generator 122 and electric drive motors 124. For example, the internal combustion engine 104 is a diesel and / or natural gas engine that generates a torque output which is transferred to the generator 122, which is mechanically connected to the internal combustion engine 104. In one embodiment herein, the internal combustion engine 104 is a multi-fuel engine that operates on diesel fuel and natural gas, but in other examples, the internal combustion engine 104 can use various combinations of fuels other than diesel and natural gas.

[0034] The generator 122 produces electrical energy that can be stored and subsequently used to power a variety of downstream components. For example, the generator 122 can be electrically connected to several traction motors 124, and the generator 122 can supply electrical power to the multiple traction motors 124. As shown, each of the multiple traction motors 124 is connected to one of several wheels 112 to provide tractive force to propel the rail vehicle 106. One example design includes one traction motor per wheelset. As shown here, six pairs of traction motors correspond to each of the six pairs of wheels of the rail vehicle. In another example, the alternator / generator 122 can be connected to one or more resistive nets 126.The resistive nets 126 can be designed to dissipate excess motor torque via heat generated by the grids from the electricity produced by the alternator / generator.

[0035] In some embodiments, the vehicle system 100 may include a turbocharger 120 arranged between the intake duct 114 and the exhaust duct 116. The turbocharger 120 increases the ambient air charge drawn into the intake duct 114 to provide a greater charge density during combustion, thereby increasing the power output and / or efficiency of the internal combustion engine operation. The turbocharger 120 may include a compressor (not shown) that is at least partially driven by a turbine (not shown). Although a single turbocharger is included in this case, the system may have multiple turbine and / or compressor stages.

[0036] In some embodiments, the vehicle system 100 may also include an aftertreatment system (in Fig. 3 shown as an aftertreatment device 314) which is connected in the exhaust gas duct upstream and / or downstream of the turbocharger 120. In one embodiment, the aftertreatment system may include a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF). In other embodiments, the aftertreatment system may also or alternatively include one or more emission control devices. Such emission control devices may include a selective catalytic reduction (SCR) catalyst, a three-way catalyst, a NOₓ catalyst, or a diesel particulate filter (DPF) catalyst. x -Trap or various other devices or systems.

[0037] The vehicle system 100 may further comprise an exhaust gas recirculation (EGR) system 130, which is connected to the internal combustion engine 104 and directs exhaust gas from an exhaust port 116 of the internal combustion engine 104 to the intake port 114 downstream of the turbocharger 120. In some embodiments, the exhaust gas recirculation system 130 may be connected exclusively to a group of one or more donor cylinders of the internal combustion engine (also referred to as a donor cylinder system). As in Fig. As shown in Figure 1, the EGR system 130 has an EGR channel 132 and an EGR cooler 134 to reduce the temperature of the exhaust gas before it enters the intake channel 114. By introducing exhaust gas into the combustion engine 104, the amount of oxygen available for combustion is reduced, thereby lowering the combustion flame temperatures and the formation of nitrogen oxides (e.g., NOₓ). x ) is reduced.

[0038] In some embodiments, the EGR system 130 may further comprise an EGR valve for controlling the amount of exhaust gas that is recirculated from the exhaust port 116 of the internal combustion engine 104 to the intake port 114 of the internal combustion engine 104. The EGR valve may be an on / off valve controlled by the control unit 110, or it may, for example, control a variable amount of EGR. As in the non-restrictive embodiment of Fig. As shown in Figure 1, the EGR system 130 is a high-pressure EGR system. In other embodiments, the vehicle system 100 may additionally or alternatively have a low-pressure EGR system that directs EGR from below the turbine to above the compressor.

[0039] As in Fig. As shown in Figure 1, the vehicle system 100 further comprises a cooling system 150. The cooling system 150 circulates coolant through the internal combustion engine 104 to absorb engine waste heat and deliver the heated coolant to a heat exchanger, for example, a heat sink 152. A fan 154 may be connected to the heat sink 152 to maintain an airflow through the heat sink 152 when the vehicle 106 is moving slowly or is stopped while the internal combustion engine is running. In some examples, the speed of the fan may be controlled by a control device, for example, the control device 110. Coolant cooled by the heat sink 152 enters a tank 156. The coolant may then be pumped by a water or coolant pump (not shown) back to the internal combustion engine 104 or to another component of the vehicle system, for example, the EGR cooler.

[0040] The rail vehicle 106 further comprises an internal combustion engine control unit 110 (hereinafter referred to as the control unit) for controlling various components related to the rail vehicle. For example, various components of the vehicle system can be connected to the control unit via a connection channel or data bus. In one example, the control unit 110 comprises a computer control system. The control unit 110 can additionally or alternatively comprise a memory comprising a non-volatile, computer-readable storage medium (not shown) containing code that enables onboard monitoring and control of the rail vehicle's operation.

[0041] The control unit 110 can receive information from multiple sensors and can send control signals to multiple actuators. The control unit 110 controls and monitors the entire rail vehicle 106 and can be configured to receive signals from various internal combustion engine sensors, as described in more detail herein, in order to determine operating parameters and conditions and, accordingly, to adjust various internal combustion engine actuators to control the operation of the rail vehicle 106.For example, the combustion engine control unit 110 can receive signals from various combustion engine sensors, including, among other things, combustion engine speed, combustion engine load, intake manifold pressure, boost pressure, exhaust pressure, ambient pressure, ambient temperature, exhaust gas temperature, particulate filter temperature, particulate filter back pressure, engine coolant pressure, gas temperature in the EGR cooler, and the like. Accordingly, the control unit 110 can control the rail vehicle 106 by sending commands to various components, such as the traction motors 124, the alternator / generator 122, cylinder valves, fuel injectors, a throttle, and the like. Other actuators can be connected to various locations in the rail vehicle.

[0042] Fig. Figure 2 shows an embodiment of a combustion chamber or cylinder 200 of a multi-cylinder internal combustion engine, for example the internal combustion engine 104, which is referred to above. Fig. The cylinder 200 can be defined by a cylinder head 201, which houses the intake and exhaust valves and a fuel injector, which is described below, and by a cylinder block 203. In some examples, each cylinder of the multi-fuel engine can have a separate cylinder head connected to a common cylinder block.

[0043] The internal combustion engine can be controlled, at least in part, by a control system that includes a control unit 110, which is further connected to a vehicle system, for example, the one referred to above. Fig. The vehicle system 100 described in section 1 communicates with the control unit 110. As described above, the control unit 110 can also receive signals from various sensors, including, among others, an internal combustion engine speed from a crankshaft speed sensor 209, an internal combustion engine load, a boost pressure, an exhaust gas pressure, an ambient pressure, a CO2 level, an exhaust gas temperature, and an NOₓ level. xThis includes emissions, an engine coolant temperature (ECT) from a temperature sensor 230 connected to a coolant sleeve 228, etc. For example, a crankshaft speed sensor could be a Hall effect sensor, a variable reluctance sensor, or a linear variable differential transducer designed to determine crankshaft speed based on the speed of one or more teeth on a crankshaft gear. Accordingly, the control unit 110 can control the vehicle system by sending commands to various components such as an AC generator or alternator, cylinder valves, a throttle, fuel injectors, or the like.

[0044] The cylinder (i.e., the combustion chamber) 200 can have combustion chamber walls 204 within which a piston 206 is arranged. The piston 206 can be connected to a crankshaft 208 such that a reciprocating motion of the piston is converted into a rotary motion of the crankshaft. In some embodiments, the internal combustion engine can be a four-stroke engine in which each of the cylinders fires in a firing sequence during two revolutions of the crankshaft 208. In other embodiments, the internal combustion engine can be a two-stroke engine in which each of the cylinders fires in a firing sequence during one revolution of the crankshaft 208.

[0045] Cylinder 200 receives intake air for combustion from an intake manifold that includes an intake manifold 210. The intake manifold 210 receives intake air via an intake trailing arm. The intake manifold 210 can communicate with other cylinders of the internal combustion engine in addition to cylinder 200, or it can communicate exclusively with cylinder 200.

[0046] Exhaust gas resulting from combustion in the internal combustion engine is delivered to an outlet which includes an outlet pipe 212. Exhaust gas flows through the outlet pipe 212, in some embodiments to a turbocharger (in Fig. (2 not shown) and into the atmosphere via an exhaust manifold. The exhaust pipe 212 can also receive exhaust gases from other cylinders of the internal combustion engine, for example in addition to cylinder 200.

[0047] Each cylinder of the internal combustion engine can have one or more intake valves and one or more exhaust valves. For example, the illustrated cylinder 200 has at least one intake poppet valve 214 and at least one exhaust poppet valve 216, which are arranged in an upper region of the cylinder 200. In some embodiments, each cylinder of the internal combustion engine, including cylinder 200, can have at least two intake poppet valves and at least two exhaust poppet valves, which are arranged on the cylinder head.

[0048] The intake valve 214 can be controlled by the control unit 110 via an actuator 218. Likewise, the exhaust valve 216 can be controlled by the control unit 110 via an actuator 220. Under certain conditions, the control unit 110 can modify the signals output to the actuators 218 and 220 to control the opening and closing of the respective intake and exhaust valves. The positions of the intake valve 214 and the exhaust valve 216 can be determined by the respective valve position sensors 222 and 224. The valve actuators can be, for example, of the electric valve actuation type, the cam actuation type, or a combination thereof.

[0049] The intake and exhaust valve timing can be controlled simultaneously, or any possible variable intake cam timing, variable exhaust cam timing, dual independent cam timing, or fixed cam timing can be used. In other embodiments, the intake and exhaust valves can be controlled by a common valve actuator or actuation system, or by a variable valve timing system. Furthermore, the intake and exhaust valves can be controlled by the control device based on operating conditions to exhibit a variable lift.

[0050] In some embodiments, each cylinder of the internal combustion engine can be designed to be equipped with one or more fuel injectors that supply it with fuel. As a non-limiting example, [reference to relevant example] Fig. 2 the cylinder 200, which has a fuel injector 226. The fuel injector 226 shown is directly connected to the cylinder 200 to inject fuel directly into it. In this way, the fuel injector 226 provides so-called direct injection of fuel into the combustion cylinder 200. The fuel can be supplied to the fuel injector 226 from a high-pressure fuel system comprising a fuel tank 232, fuel pumps, and a fuel line (not shown). In one example, the fuel is diesel fuel, which is combusted in the combustion engine by compression ignition. In other non-limiting embodiments, the fuel can be gasoline, kerosene, biodiesel, or other petroleum distillates of similar density, combusted by compression ignition (and / or spark ignition).As described in more detail below, each cylinder of the internal combustion engine can also be designed to receive gaseous fuel (e.g., natural gas) as an alternative or in addition to diesel fuel. The gaseous fuel can be supplied to cylinder 200 via the intake manifold, as explained below, or via another suitable supply mechanism.

[0051] Fig. Figure 3 shows a sketch of an internal combustion engine system 300, which includes an internal combustion engine 104 with several cylinders 200. Thus, the internal combustion engine system 300 has the above with reference to Fig. The combustion engine 104 described in section 1 is used. The combustion engine 104 receives intake air for combustion from an intake manifold 302. The intake manifold 302 receives intake air from an intake duct 114, which draws ambient air from a (in Fig. The air filter (shown in Figure 1) receives air from outside a vehicle in which the internal combustion engine 104 may be located. The flow of intake air into the intake manifold 302 can be controlled by a throttle 312, the position of which can be controlled by the control device 110.

[0052] In the Fig. In the embodiment shown in Figure 3, the internal combustion engine 104 is a V-12 engine with twelve cylinders. For example, the internal combustion engine could be a V-6, V-8, V-10, V-16, I-4, U-6, I-8, or another type. Due to the design of the internal combustion engine, it has a first cylinder bank with six cylinders (e.g., cylinders 1-6) and a second cylinder bank with six cylinders (e.g., cylinders 7-12). The intake manifold 302 is arranged between the two cylinder banks and is designed to supply intake air to the individual cylinders of each bank via several intake pipes. Even if this is in Fig. As shown in Figure 3, each intake manifold is connected to a separate cylinder head, which at least partially defines a cylinder. Thus, intake air flowing through the intake manifold is distributed to multiple intake manifolds, each of which is in fluid contact with a separate cylinder head of the internal combustion engine.

[0053] The intake manifold 302 is designed to supply intake air to the cylinders of the internal combustion engine as described above. However, the intake manifold 302 also has additional passages for draining coolant from the internal combustion engine and for supplying gaseous fuel to the engine. Thus, the intake manifold 302 has a first channel 304 designed for an intake air flow. The first channel 304 is connected to the multiple intake pipes. The first channel 304 receives intake air from intake duct 114.

[0054] To allow coolant to drain from the internal combustion engine, the intake manifold 302 has a second channel 306. The second channel 306 receives, for example, coolant that is routed to the outside from the individual cylinder heads, and the second channel returns the coolant to the general engine coolant system 318. The engine coolant system 318 can have one or more cooling components, for example, a heat sink (e.g., the heat sink 152 of Fig. 1) a coolant tank (e.g., tank 156), coolant lines, pumps, and / or other components. Thus, coolant is pumped from the engine coolant system to the internal combustion engine 104, where it flows through one or more jackets of the cylinder block and / or cylinder head (e.g., coolant sleeve 228) to cool the internal combustion engine. The coolant then drains via outlet lines leading from each cylinder head to the second channel 306, and the coolant is returned to the engine coolant system.

[0055] In some operating modes, the 104 internal combustion engine can operate on both liquid fuel combustion (i.e., diesel fuel) and gaseous fuel combustion (i.e., natural gas). While liquid fuel, as described above with reference to... Fig. As described in section 2, gaseous fuel can be supplied to the individual cylinders via a third channel 308 of the intake manifold 302. Fig. As shown in Figure 3, the third channel 308 of the intake manifold 302 can receive a supply of gaseous fuel from a fuel gas tank 316 via one or more fuel gas lines, pumps, pressure regulators, etc. In some embodiments, the fuel gas tank 316 can be located remotely from the internal combustion engine 104, for example, on another railway car (e.g., on a fuel tender car), and the gaseous fuel can be supplied to the internal combustion engine 104 via one or more fuel lines running through the separate cars. However, in other embodiments, the fuel gas tank 316 can be located in the same vehicle as the internal combustion engine 104. The third channel 308 can have several gas inlet valves, each configured to supply gaseous fuel from the third channel 308 to a corresponding cylinder head.

[0056] Exhaust gas resulting from combustion in the internal combustion engine 104 is supplied to an exhaust gas channel 116, where the exhaust gas is treated by the aftertreatment device 314 and / or flows through one or more turbochargers before being released into the atmosphere. In the Fig. In the design shown in Figure 3, each cylinder bank has an exhaust manifold. For example, in Fig. Figure 3 shows exhaust manifolds 310a and 310b. Each exhaust manifold receives exhaust gas emitted from the individual cylinders of a respective cylinder bank (via an exhaust pipe of the respective cylinder head, for example exhaust pipe 212 of Fig. 2) Each exhaust manifold 310a, 310b directs exhaust gas to the common exhaust channel 116.

[0057] Thus, the internal combustion engine systems described above supply multiple cylinders, each cylinder having a liquid fuel injector designed to inject a liquid fuel (e.g., diesel). Furthermore, each cylinder is designed to receive gaseous fuel (e.g., natural gas). A mixture of gaseous fuel and air can be combusted via injection of liquid fuel from a liquid fuel injector. The internal combustion engine can be designed to operate over a wide range of quantities of gaseous and liquid fuel, referred to herein as the substitution ratio. For example, under certain conditions it may be desirable to operate the internal combustion engine with a substitution ratio of zero, where all combustion energy is obtained from the combustion of liquid fuel.Under other conditions, it may be desirable to operate the internal combustion engine with a substitution ratio greater than zero, whereby at least part of the combustion energy is obtained from gaseous fuel.

[0058] As explained above, under certain conditions it may be desirable to operate the internal combustion engine with a substitution ratio close to 100%. Since the combustion of the gaseous fuel relies on the injection of at least some liquid fuel, the liquid fuel injectors can also be operated at high substitution ratios to provide some liquid fuel to the individual cylinders. However, each liquid fuel injector may have a minimum amount of liquid fuel injection, known as the turn-down point, below which the injection quantity is not linearly correlated with the duration the injector is open (also known as the opening time). Fig. Figure 8 is a diagram 800, which presents an example of an injector delivery curve 802 for a liquid fuel injector and shows that the fuel injection quantity (e.g., the volume, plotted on the vertical axis) increases linearly with increasing duration above a first injector opening duration d1 (where the duration is plotted on the horizontal axis). However, below this point, which is referred to as the turn-down point 804, the fuel delivery quantity may not change linearly with a change in duration; for example, the quantity may decrease faster than the duration. As shown by the combustion curve 806, at a second duration d2 below the turn-down point, stable combustion may no longer occur due to the small amount of injected fuel, and misfiring may occur.The misfire can be detected based on the level of a half-order frequency component, which is determined by a half-order misfire monitoring device described below.

[0059] The turn-down point can be different for each individual injector. As an example, it shows... Fig. Figure 9 shows a diagram 900 that displays several injector delivery curves 902 for multiple liquid fuel injectors. As illustrated by the multiple injector delivery curves 902, the turn-down points within a given set of injectors can differ considerably. To ensure stable combustion, each fuel injector can typically be operated based on the highest turn-down point of all cylinders or based on the longest injector opening duration that ensures stable combustion. As illustrated by the curves 902, if the individual injectors are operated for the same duration (for example, the duration required to ensure stable combustion in the injector with the highest turn-down point, as shown in Figure 902), the injector will have a different turn-down point. Fig. 9 through line 904), a highly variable amount of liquid fuel is delivered to the individual injectors. Such operation can reduce the amount of gaseous fuel that can be used to run the internal combustion engine. For example, the injector with the lowest turn-down point may be operated for a duration much longer than the minimum duration required to sustain combustion in that cylinder.

[0060] As described in more detail below, the shortest duration for which each injector can be operated while maintaining stable combustion can be determined during a tuning routine. The fuel delivery quantity of each injector can be based on the duration for which each injector remains open. Thus, both the fuel quantity and the opening duration can be referenced when describing the tuning routine. To simplify the description, the opening duration will be used from now on.

[0061] The tuning routine can involve successively shortening the opening duration for each injector and monitoring for misfires. Once a misfire is detected, the opening duration of the misfiring cylinder's injector can be lengthened until the misfire ceases. This opening duration can then be set as the shortest duration at which that injector can operate reliably. If very high proportions of gaseous fuel are required (e.g., 99%), this injector can then be operated at its shortest opening duration. This process can be repeated for each cylinder individually. Consequently, if very high proportions of gaseous fuel are required (e.g., 99% gaseous fuel), each injector can be operated at a different duration, resulting in the same quantity of liquid fuel being delivered in each. This is represented by the multiple injector delivery curves 906 in Fig. Figure 9 shows where each injector is operated for a different duration, resulting in an equal fuel delivery volume of 908.

[0062] It will now be on Fig. 4 Reference is made to a method 400 for tuning several liquid fuel injectors of an internal combustion engine (for example, the internal combustion engine 104 of Fig. 1 - Fig. 3) is shown. The procedure 400 can be carried out by a control unit, for example the control unit 110 of Fig. 1 - Fig. 3, according to non-volatile instructions stored therein. In 402, procedure 400 involves determining internal combustion engine operating parameters. The determined operating parameters may include, among others, the internal combustion engine speed, the internal combustion engine torque requirement, the internal combustion engine temperature, and other operating parameters. In 404, procedure 400 involves determining whether conditions for performing the injector tuning are met. The conditions for performing the injector tuning may include that the routine has not been performed previously (e.g., during the first operating period after the internal combustion engine was manufactured or following maintenance), or that a threshold period (age, internal combustion engine cycles, distance traveled by the vehicle, etc.) has elapsed since a previously performed routine.

[0063] The conditions for entering the tuning routine can also include operating conditions that allow the use of a high proportion of gaseous fuel (e.g., close to 100%). Internal combustion engines designed to run on both liquid and gaseous fuels can operate on as much gaseous fuel as possible while still maintaining the required engine power. For example, in standard liquid-fueled internal combustion engines, such as diesel engines, 100% of the engine's power output can be derived from the combustion of diesel fuel. In multi-fuel engines, some of the engine's power can be derived from gaseous fuel, while the remaining power can be derived from liquid fuel.For example, as much as 99% of the power produced by an internal combustion engine can be derived from the combustion of gaseous fuel, with the remaining 1% coming from the combustion of diesel fuel. The amount of gaseous fuel that is "substituting" for liquid fuel can be referred to as the substitution ratio. The substitution ratio indicates the proportion of the internal combustion engine's power derived from gaseous fuel. For example, a substitution ratio of 80 indicates that 80% of the power is derived from gaseous fuel, while a substitution ratio of 50 indicates that 50% of the power is derived from gaseous fuel. A substitution ratio of 0 indicates purely liquid operation.

[0064] The substitution ratio can be adjusted based on the combustion engine temperature, the desired fuel type, the throttle position, the relative fuel levels in the individual fuel tanks (e.g., more liquid fuel can be used if the gaseous fuel level is below a certain threshold), the vehicle's location (e.g., whether the vehicle is in a tunnel), and / or other parameters. Thus, the entry conditions can include the combustion engine temperature, throttle position, vehicle location, etc., each within a range that allows operation using a large quantity of gaseous fuel (e.g., 99%).

[0065] If the entry conditions are not met, procedure 400 continues to 402 to monitor the operating conditions. If the conditions are met, procedure 400 continues to 406 to operate all cylinders of the internal combustion engine with a substitution ratio of zero (e.g., no use of gaseous fuel). Then, at 408, all cylinders are operated with a predetermined safe substitution ratio, for example, 80. The predetermined safe substitution ratio may involve the use of gaseous fuel in a proportion known to produce stable combustion (i.e., without misfires).

[0066] At 410, a misfire monitoring device is initiated to monitor for cylinder misfires. The misfire monitoring device is described in more detail below with reference to Fig. 5 described. In short, the misfire monitoring device can detect a misfire in one or more cylinders based on half-order or higher torsional vibrations generated by the internal combustion engine and measured by a crankshaft speed sensor.

[0067] In 412, procedure 400 involves shortening the opening duration of the injector of the first cylinder of the internal combustion engine. The opening duration can be shortened continuously or incrementally, each at a suitable rate. During the shortening of the injector's open duration, the misfire monitoring device is operated to determine whether a misfire occurs in the first cylinder, which may indicate that the liquid fuel injection quantity has dropped to a level insufficient to sustain combustion.

[0068] Thus, procedure 400 at 414 includes a determination of whether a misfire is detected in the first cylinder. If no misfire is detected, procedure 400 returns to 412 to continue shortening the injector opening duration. If a misfire is detected, procedure 400 continues to 416 to lengthen the opening duration of the first cylinder's injector. The injector opening duration can be lengthened until the misfire monitoring device no longer detects a misfire in the first cylinder. At 418, the first cylinder's injector opening duration at which the misfire ceases is stored, and at 420, the tuning process is repeated for the remaining cylinders (e.g.,The opening duration of an injector in a second cylinder is shortened, while the substitution ratio of the remaining cylinders is kept constant at the predetermined safe level; the misfire monitoring device indicates when a misfire is detected in the second cylinder; the opening duration of the injector of the second cylinder is extended until the misfire stops; and the duration at which the misfire stops is stored for the injector of the second cylinder.

[0069] After the tuning routine for all injectors of all cylinders has been executed, each injector will operate with an opening duration determined by the tuning routine, provided the operating conditions allow the internal combustion engine to run almost exclusively on gaseous fuel (e.g., with only enough liquid fuel to sustain combustion). In some examples, this may involve each injector delivering the same amount of liquid fuel. The misfire monitoring device can continue its operation to detect whether a misfire is occurring in any of the cylinders. If a misfire is detected, the opening duration of the injector in the misfiring cylinder can be extended to stop the misfire.

[0070] In some examples, the stored minimum opening duration for this injector can be adjusted if a misfire is later detected for this cylinder.

[0071] The tuning routine described above determines the minimum duration for which each injector can remain open during a fuel injection event while maintaining combustion during operation under a predefined set of parameters (e.g., an operating point of the internal combustion engine where the use of a large quantity of gaseous fuel is permissible). However, if the internal combustion engine operates at other speed / load points, misfiring may occur if the liquid fuel injectors are each operated with the minimum opening duration determined above. Therefore, the tuning process described above can be performed for a range of different speed / load points, and the minimum opening duration for each injector at each respective speed / load point can be determined.In this way, each cylinder can have an individual misfire limit, which is determined for each operating point of the internal combustion engine. Under some conditions, the misfire limit may be above the absolute shortest time for which each injector must be open, while under other conditions, the misfire limit may be at or below the shortest time for which each injector must be open.After the tuning routine has been executed for each speed / load point, when the internal combustion engine enters a specific speed / load range, the shortest opening duration of the liquid fuel injector for that speed / load range can be determined for each injector, and each cylinder can be operated with a substitution ratio that delivers the greatest possible amount of gaseous fuel while still enabling the desired power output and the shortest opening duration of the liquid fuel injector.

[0072] As explained above, a misfire monitoring device can be used in the tuning routine to detect misfiring cylinders. The misfire monitoring device can also be run during other internal combustion engine operating events, and in some examples, it can be run during all internal combustion engine operating events. Fig. Figure 5 is a flowchart illustrating a procedure 500 for operating a misfire monitoring device. The procedure 500 can be executed by a control unit, for example, a control device 110, according to non-volatile instructions stored therein. In some examples, the control device 110 may have multiple nodes, be hierarchically organized, be multi-threaded, and / or have another configuration that allows part of the procedure 500 to be executed by a first level of the control device, while another part of the procedure 500 is executed by a second, different level of the control device. Further details of the hierarchical process are described below. The procedure 500 can detect half-order or higher torsional vibrations, alone or in combination.In one example, Method 500 can only detect half-order torsional vibrations, for instance, if the internal combustion engine is a four-stroke engine. In other examples, Method 500 can detect first-order torsional vibrations, for instance, if the internal combustion engine is a two-stroke engine. The detection of torsional vibrations of other orders is within the scope of this disclosure.

[0073] In procedure 502, procedure 500 involves determining a time interval (X). nThe time interval between the passage of each tooth of a crankshaft sprocket past a crankshaft sensor for a full internal combustion engine cycle (e.g., two crankshaft revolutions). For example, the crankshaft sprocket can have multiple teeth, and the time interval between when a first tooth and a second, adjacent tooth pass the crankshaft sensor can be determined for each tooth of the sprocket. For example, the sprocket might have 90 teeth, and thus approximately 180 x n Sample values ​​are recorded during an internal combustion engine cycle.

[0074] In 504, each value of X n inserted into a recursive summation algorithm, for example a Goertzel sum. Further details regarding the Goertzel sum are given below with reference to Fig. As described in section 6. In short, the Goertzel sum calculates a term (Sn) for each X. n based on two preceding X n-terms and a calibratable coefficient. At 506, the last two terms of the Goertzel sum, S N and S N-1 , output and passed to a model at 508, where they are used to determine an amplitude and a phase. Further details regarding this model are given below with reference to Fig. 7 is specified. In short, the multiple X n Sample values ​​acquired during the combustion engine cycle represent a signal that can be processed to determine its amplitude and phase. Based on the amplitude, it can be determined whether a misfire is present, and if a misfire is present, the signal phase can be used to determine which cylinder is misfiring.

[0075] Thus, procedure 500 at 510 includes determining whether the amplitude is greater than a threshold amplitude. The threshold amplitude can be a suitable amplitude, for example, an amplitude specified when no cylinder misfires. If the amplitude is greater than the threshold, procedure 500 proceeds to 512 to indicate that a misfire has been detected. At 514, procedure 500 optionally includes determining which cylinder is misfiring, based on the signal phase calculated above. At 516, one or more operating parameters of the internal combustion engine can be adjusted and / or a misfire message can be issued. For example, in response to a detected misfire, a liquid fuel injection rate can be increased, fuel injection timing can be adjusted, or other parameters can be modified.Furthermore, the issued message may, for example, include a notification to the operator of the vehicle in which the combustion engine is installed, via a warning light or the display of a diagnostic code. In this case, procedure 500 returns to the beginning.

[0076] If the amplitude at 510 is not greater than the threshold, the procedure continues from 500 to 518 to indicate that no misfire is detected, and at 520 to maintain the current operating parameters. Then the procedure returns to the beginning at 500.

[0077] Thus, Method 500 monitors for misfiring cylinders by analyzing crankshaft torsional vibrations generated by the combustion cylinders. During operation without misfiring, the torsional vibrations are relatively low. However, if a cylinder misfires and therefore does not contribute to the crankshaft torque, higher-order torsional vibrations can increase. These can be detected based on an output from the crankshaft speed sensor.

[0078] As described above, the misfire monitoring device comprises two sections: a first section in which the Goertzel sum is calculated using the acquired output from the crankshaft sensor to output two terms. These terms are then fed into the second section of the misfire monitoring device, where they are used to calculate a phase and amplitude to detect a misfire and the cylinder in which it occurred. Each section of the monitoring device can be executed at a different logical level of the control device. For example, the first section can be executed at a lower level, and the second section at a higher level. This might involve executing the two sections on different nodes or in different threads or subprocesses of a multi-threaded processor.

[0079] Fig. 6 - Fig. Figure 7 shows in more detail the recursive Goertzel algorithm described above, which uses the variation of the existing time intervals between the teeth of the crankshaft position sensor to calculate the orders of the crankshaft torsional vibrations of the internal combustion engine in order to measure internal combustion engine operation. The recursive Goertzel sum is calculated between the passage of timing and control teeth in the lower level of the control unit. After an internal combustion engine cycle, the last two terms of the sum are reported to the higher-level control unit for use in calculating the order and phase, which can be used to detect weak and misfiring cylinders. In a four-stroke engine, individual weak or misfiring cylinders exhibit enhanced half-order torsional vibrations, and multiple misfiring cylinders exhibit enhanced first and higher orders.

[0080] Now, first, we will turn to procedure 600 of Fig. Reference is made to Figure 6, which illustrates the acquisition of sample values ​​and the recursive summation performed with the signal from the crankshaft sensor. As previously explained, the crankshaft of the internal combustion engine has a timing gear with evenly spaced teeth to control the injection of fuel at the correct angular position of the engine. The passage of each tooth is read by the control unit. Although the teeth are evenly spaced, the time between the teeth varies, D(T). n ) (also known as X) n(designated as) due to the torsional vibration of the crankshaft, caused by the pulsating nature of the ignition in the individual cylinders and the elastic properties of the crankshaft. When all cylinders fire simultaneously, their torque pulses applied to the crankshaft are nearly equal, and the phase differences between the cylinders result in a low net value for the lower vibration orders. If the torque of one cylinder is lower or higher, the other torque values ​​are not balanced, and a higher net value for the crankshaft vibration orders can be calculated. It can be more efficient to calculate the terms of the recursive Goertzel sum between the passage of each timing tooth in the lower part of the timing device.

[0081] Therefore, procedure 600 in 602 involves querying a value X. n, which has been calculated as described above (e.g., the time interval between when the crankshaft speed sensor detects a first tooth, and when the sensor detects a second tooth, where the second tooth is the tooth immediately following the first tooth). At 604, a first term S n based on X n , S n-1 and S n-2 determined. To S n To determine the queried value X n into the equation S n = X n + Coeff·S n-1 - S n-2 entered, where the value for coeff depends on the calculated order (e.g. half order, first order, etc.), and where S n-1 and S n-2 the two previously calculated S n are. After S n has been calculated, S n-1 on S n-2 set up, S n will be on S n-1The number of samples is incremented by one at 606. Then, at 608, it is determined whether the sample count is at least as high as a threshold count. The threshold count can be the number of teeth detected by the sensor in one full combustion engine cycle (e.g., during two crankshaft revolutions, and thus twice the number of teeth on the wheel), or any other suitable count indicating that sufficient data has been acquired to allow a determination of the torsional vibration order(s). In an example where the wheel has 90 teeth, the count can be 180. If the count is not greater than the threshold count, procedure 600 returns to 602, and S n will be for the next X n calculated. If the count value is equal to or greater than the count value of the threshold, the last two terms, S N and S N-1The result is output at 610, and all values ​​are reset at 612 to start the next combustion engine cycle. In this way, the sum for all teeth is performed in two crankshaft revolutions, and then the amplitude is calculated (described below).

[0082] The last two sum terms, S N and S N-1These values ​​are reported to a higher logical level of the control unit, where the amplitude and phase of the torsional vibration order frequency for that combustion engine cycle are calculated. The amplitude and / or phase can be used to measure the overall unevenness of the combustion engine or to detect individual defective, weak, or misfiring cylinders. Although the procedures described herein involve determining the at least two sum terms at the lower logical level and communicating them to the higher logical level for further processing, other configurations are also possible. For example, the gear tooth data (e.g., the time interval between the passage of each tooth on the gear) can be passed from the lower level to the higher level, and all calculations can be performed at the higher level.

[0083] Fig. Figure 7 is a flowchart that describes procedure 700 for determining the amplitude and phase of the frequency analyzed in procedure 600. In figure 702, procedure 700 involves retrieving S N and S N-1 from the lower logical level of the control unit. As above with reference to Fig. As explained in section 6, S N and S N-1 the last two terms output by the recursive Goertzel algorithm. Thus, S N and S N-1 The desired frequency component (e.g., half the order) for the entire sampled signal is represented by these two terms, which include real and imaginary frequency components. The signal's amplitude and phase can be determined from these two terms. Thus, in the case of 704, the amplitude is determined based on a single signal strength measurement. The last two terms are then entered into the equation to calculate the amplitude. Amp=((SN⋅wr−SN−1)2+(SN⋅wi)2)1 / 2⋅2 / N

[0084] In the equation above, W represents r represents a real value of w (e.g., the cosine of w), where w = (2π / N)·k and k is a constant based on a sampling length, a target frequency, and a sampling frequency. In the equation above, W represents i represents an imaginary value of w (e.g., the sine of w).

[0085] For 706, the phase can be calculated according to the following equation: Phase=720−MOD(ATAN2(SN⋅wr−SN−1,SN⋅wi)⋅2+Off,720).

[0086] In the equation above, MOD can denote a modulo function, ATAN2 can denote an arctangent with a two-argument function, and Off can be an offset, for which an example might be based on the position of the internal combustion engine at the beginning of the combustion cycle. As described above, the amplitude can be compared to a threshold value to determine whether a misfire is present. If a misfire is present, the phase can indicate which cylinder misfired. In an example, the phase calculated above could be zero if a misfire is present. If a misfire is present, the phase relative to the initial position of the internal combustion engine can be used to determine which cylinder misfired.

[0087] In some cases, variations in combustion can occur between individual cylinders. These variations are caused by differences in the compression ratio, a ring seal, the air-fuel ratio, deposits, etc., resulting in vibrations greater than half the order. The variation between individual cylinders contributes to the variation caused by injector variation; therefore, the crankshaft vibration monitoring system may be unable to identify the cause of the variation, but the remedy is similar in each case. For example, the proportion of liquid fuel to individual cylinders or to the engine as a whole can be increased.

[0088] There may come a point where the injector or cylinder conditions are so unfavorable that the internal combustion engine must revert to 100% liquid fuel, reduce power, or shut down to protect itself from further damage.

[0089] Furthermore, the crankshaft torsional vibration monitoring system can also detect a gradual deterioration in combustion quality. If the ignition of the gaseous fuel becomes less efficient, the variation in power output between individual cycles and between all cylinders in a multi-cylinder engine can increase. The term "coefficient of variation" (COV) is the standard deviation of the cylinder's power output divided by the mean power output. The COV value can be monitored and optimized by adjusting the fuel delivery time for individual cylinders or for the entire engine.

[0090] As shown in diagram 1000 of Fig. As shown in Figure 10, the first / second order reaction is directly proportional to the combustion variation (e.g., linearly proportional). As shown by Fig. 11 - Fig. As shown in Figure 14, the amplitude of the first / second order is greater the larger the COV is. As an example, diagram 1100 of Fig. 11 the cylinder peak pressure for six cylinders of a 12-cylinder engine operating at 2% COV, and diagram 1200 of Fig. Figure 12 shows the peak cylinder pressure for each of the six cylinders when the internal combustion engine is operating at 10% COV. At 2% COV, the first-order amplitude is 0.025, while at 10% COV, the first-order amplitude is 0.120. As can be seen from... Fig. 13 - Fig. As can be seen from Figure 14, the crankshaft vibration varies from combustion engine cycle to combustion engine cycle (e.g., cases 1-6) when the combustion engine operates at 10% COV (shown in diagram 1400 of Figure 1400). Fig. 14), to a greater extent than when the internal combustion engine operates at 2% COV (shown by diagram 1300 of Fig. 13).

[0091] One embodiment of the system comprises an internal combustion engine with multiple cylinders connected to a crankshaft, a crankshaft speed sensor, and a control unit. The control unit is designed to measure a half-order torsional vibration of the internal combustion engine based on a signal from the crankshaft speed sensor, to determine the phase and amplitude of the half-order torsional vibration, and, if the amplitude exceeds a threshold value, to indicate a misfire in at least one of the multiple cylinders. In the event of a misfire being indicated, the control unit may further be designed to determine, based on the phase, which of the multiple cylinders is misfiring. Alternatively, the control unit may also be designed to increase the fuel injection quantity for the misfiring cylinder in the event of a misfire being indicated.The control device can additionally or alternatively be designed to determine a degree of combustion variation between the multiple cylinders based on the amplitude.

[0092] One embodiment relates to a method comprising: measuring one or more torsional vibration orders of a multi-cylinder internal combustion engine based on signals from a crankshaft speed sensor; determining the amplitude of one or more torsional vibration orders; and, if the amplitude is greater than a threshold amplitude, indicating a misfire in at least one of the multiple cylinders. In the event of a misfire being indicated, the method may further comprise determining, based on the phase, which of the multiple cylinders is misfiring. The method may also, or alternatively, in the event of a misfire being indicated, further comprise increasing the fuel injection quantity for the misfiring cylinder. The method may additionally, or alternatively, comprise determining the degree of combustion variation between the multiple cylinders based on the amplitude.In one example, one or more torsional vibration orders can include a half-order torsional vibration.

[0093] One embodiment relates to a system comprising: an internal combustion engine with multiple cylinders, wherein the internal combustion engine is capable of receiving at least one first fuel and one second fuel; multiple fuel injectors for injecting the first fuel into the multiple cylinders; and a control device. The control device is designed, when operating in a tuning mode, to operate the internal combustion engine on both the first fuel and the second fuel and to determine a minimum opening duration for each of the multiple injectors to maintain combustion; and, when operating in a second fuel mode, to open each injector beyond its minimum opening duration to initiate combustion.The minimum opening duration for each of the multiple injectors can be determined based on a misfire monitoring device that detects cylinder misfires based on signals from a crankshaft speed sensor. The system may additionally or alternatively include the first fuel being liquid fuel and the second fuel being gaseous fuel, and the control unit may additionally or alternatively be designed to deliver a mixture of gaseous fuel and air to the individual cylinders during the second fuel mode. The system may additionally or alternatively include the tuning mode being performed at a specific internal combustion engine speed and / or load, and the second fuel mode comprising internal combustion engine operation at that specific internal combustion engine speed and / or load.The system may additionally or alternatively include the control unit being designed to detect a cylinder misfire using the misfire monitoring device by determining a half-order torsional vibration of a crankshaft of the internal combustion engine based on the signals from the crankshaft speed sensor.

[0094] One embodiment relates to a method for a system comprising: an internal combustion engine with multiple cylinders, wherein the internal combustion engine is capable of receiving at least one first fuel and one second fuel; multiple fuel injectors for injecting the first fuel into the multiple cylinders; and a control device. The method comprises, in a tuning mode, operating the internal combustion engine with both the first fuel and the second fuel and determining a minimum opening duration for each of the multiple injectors to maintain combustion; and, in a second fuel mode, opening each injector beyond its minimum opening duration to initiate combustion.The minimum opening duration for each of the multiple injectors can be determined based on a misfire monitoring device that detects cylinder misfires based on signals from a crankshaft speed sensor. The method may additionally or alternatively include the first fuel being liquid fuel and the second fuel being gaseous fuel, and that during the second fuel mode, a mixture of gaseous fuel and air is supplied to the individual cylinders. The method may additionally or alternatively include the tuning mode being performed at a specific engine speed and / or load, and the second fuel mode comprising engine operation at that specific engine speed and / or load.The procedure can additionally or alternatively include determining a cylinder misfire by determining a half-order torsional vibration of a crankshaft of the internal combustion engine based on the signals from the crankshaft speed sensor.

[0095] One embodiment relates to a system comprising a multi-cylinder internal combustion engine connected to a crankshaft, a crankshaft speed sensor, and a control unit. The control unit is designed to measure the half-order torsional vibration of the internal combustion engine based on signals from the crankshaft speed sensor, to determine a coefficient of variation (COV) of the multi-cylinder system based on the measured half-order torsional vibration, and to adjust the fuel delivery time for one or more of the multi-cylinder system based on the COV. The COV may include a standard deviation of a power output of the multi-cylinder system divided by a mean power output.

[0096] As used herein, an element or step that is referred to in the singular and preceded by the word "a" or "an" is not to be construed as excluding the plural of such elements or steps unless expressly stated. Furthermore, references to "an embodiment" of the present invention are not to be interpreted as excluding the existence of additional embodiments that also possess the aforementioned features. Unless expressly stated otherwise, embodiments that "comprise," "include," or "have" an element or a plurality of elements with a particular property may include additional such elements that do not have that property. The terms "including" and "in which" are used as colloquial equivalents of the respective terms "comprising" and "whereby."Furthermore, the terms "first", "second" and "third", etc. are used only for differentiation and are not intended to impose any numerical requirements or a specific local order on their objects.

[0097] Various methods and systems are described for an internal combustion engine capable of running on both liquid and gaseous fuels. For example, a cylinder misfire can be detected using a misfire monitoring device. This device can detect a misfire based on signals from a crankshaft sensor. Reference symbol list 100 vehicle systems 102 rail 104 Internal combustion engine 106 Rail vehicle 110 Control unit 112 wheels 114 Intake manifold 116 Exhaust duct 120 turbochargers 122 Alternator / Generator 124 drive motors 126 resistive networks 130 EGR system 132 EGR channel 134 EGR cooling 150 Cooling system 152 heat sinks 154 blowers 156 Tank 160 air filters 200 cylinders 201 Cylinder head 202 rail 203 cylinder block 204 combustion chamber walls 206 pistons 208 Crankshaft 209 Crankshaft speed sensor 210 Intake manifold 212 Outlet pipe 214 Intake valve 216 Exhaust valve 218 Actuator 220 Actuator 222 valve position sensors 224 valve position sensors 226 Fuel injector 228 Coolant sleeve 230 temperature sensor 232 Fuel tank 300 internal combustion engine system 302 Intake manifold 304 first channel 306 second channel 308 third channel 310a Exhaust manifold 310b Exhaust manifold 312 Throttle 314 Post-treatment device 316 Fuel gas tank 318 Engine cooling system 400 procedures 402 Procedure step 404 Procedure step 406 Procedure step 408 Procedure step 410 Procedure step 412 Procedure step 414 Procedure step 416 Procedure step 418 Procedure step 420 Process step 500 procedures 502 Procedure step 504 Procedure step 506 Procedure step 508 Procedure step 510 Procedure step 512 Procedure step 514 Procedure step 516 Procedure step 518 Procedure step 520 Procedure step 600 procedures 602 Procedure step 604 Procedure step 606 Procedure step 608 Procedure step 610 Procedure step 612 Procedure step 700 procedures 702 Procedure step 704 Procedure step 706 Procedure step 800 diagram 802 Injector delivery curve 804 Turn-down point 806 Combustion curve 900 diagram 902 Injector Delivery Curves Line 904 906 Injector Delivery Curves 908 Fuel delivery volume 1000 diagram 1100 Diagram 1200 Diagram 1300 Diagram 1400 diagram d1 Injector opening duration d2 second duration

Claims

[1] System (100) exhibiting: an internal combustion engine (104) with several cylinders (200) connected to a crankshaft (208); a crankshaft speed sensor; and a control device (110) which is configured to: to measure a half-order torsional vibration of the internal combustion engine (104) based on signals from the crankshaft speed sensor; to determine the amplitude of the half-order torsional vibration; if the amplitude is greater than a threshold amplitude, indicate a misfire in at least one of the several cylinders (200); to determine a coefficient of variation (COV) of the several cylinders (200) based on the measured half-order torsional vibration; and to adjust a fuel injection duration for one or more of the multiple cylinders (200) based on the coefficient of variation (COV). [2] System (100) according to claim 1, wherein the control device (110) is further configured to determine, on the basis of a phase of the half-order torsional oscillation, which cylinder (200) of the several cylinders (200) is misfiring when a misfire is indicated. [3] System (100) according to claim 1 or 2, wherein the control device (110) is further configured to increase the amount of fuel injected into the misfiring cylinder (200) when a misfire is indicated. [4] System (100) according to one of the preceding claims, wherein the control device (110) is configured to determine for each cylinder (200) of the multiple cylinders (200) a misfire limit for each operating point of multiple operating points, based on an amplitude of the half-order torsional vibration measured over the multiple operating points. [5] System (100) according to claim 4, wherein the misfire limit for a specific cylinder (200) of the multiple cylinders (200) includes a minimum opening duration for a liquid fuel injector connected to the specific cylinder (200). [6] System (100) according to claim 4 or 5, wherein the control device (110) is further configured to operate the individual cylinders (200) of the multiple cylinders (200) with a respective predetermined ratio of gaseous fuel to liquid fuel, wherein each predetermined ratio includes a maximum amount of gaseous fuel for delivering a required engine power while remaining above a respective misfire limit. [7] System (100) exhibiting: an internal combustion engine (104) with several cylinders (200), wherein the internal combustion engine (104) is configured to operate with at least one first fuel and one second fuel; multiple fuel injectors (226) to inject the initial fuel into the multiple cylinders (200); and a control device (110) which is configured to: during operation in a tuning mode, to operate the internal combustion engine (104) with both the first fuel and the second fuel and to determine a minimum opening duration for each of the multiple injectors (226) with which combustion is maintained; and When operating in a second fuel mode, each injector (226) is opened for its specified minimum opening duration to initiate combustion, the minimum opening duration for each of the multiple injectors (226) being determined on the basis of a misfire monitoring device that detects cylinder misfire based on signals from a crankshaft speed sensor. [8] System (100) exhibiting: an internal combustion engine (104) with several cylinders (200) connected to a crankshaft (208); a crankshaft speed sensor; and a control device (110) which is configured to: to measure a half-order torsional vibration of the internal combustion engine (104) based on signals from the crankshaft speed sensor; to determine a coefficient of variation (COV) of the multiple cylinders (200) based on the measured half-order torsional vibration and on the basis of a peak cylinder pressure for each of the multiple cylinders (200); and to adjust a fuel injection duration for one or more of the multiple cylinders (200) based on the coefficient of variation (COV). [9] System (100) according to claim 1, wherein the coefficient of variation (COV) comprises a standard deviation of a power output from the multiple cylinders (200) divided by a mean power output. [10] System (100) according to claim 1 or 9, wherein the internal combustion engine (104) is configured to burn at least one first fuel and one second fuel, and wherein the control device (110) for adjusting the fuel injection duration for one or more of the multiple cylinders (200) is configured to adjust the fuel injection duration of the first fuel in relation to the second fuel.

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