Methods for operating large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engines

Abstract

This invention provides a method for operating a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine having a crosshead (9). The engine includes: a plurality of cylinders (1), each cylinder having: - an exhaust valve (4), - an exhaust valve actuation system (46) for actuating the exhaust valve (4), - a fuel delivery system (30) for delivering a first amount of fuel to the associated cylinder (1), - a pressure sensor (42) for generating a pressure signal for a specific cylinder representing the pressure in the associated cylinder (1); and an exhaust-driven turbocharger (5) for pressurizing the scavenging air for the cylinders (1). The method includes: performing closed-loop control of at least one combustion process parameter of the cylinder (1) in a cylinder-specific manner based on the pressure signal of the specific cylinder and a setpoint of the specific cylinder, the setpoint of the specific cylinder being a compensation for the specific cylinder of a common setpoint for all cylinders (1).

Description

[0001] This application is a divisional application of the invention patent application filed on November 13, 2020, with application number 202011271040.1 and invention title "Large Low-Speed ​​Turbocharged Two-Stroke Single-Flow Scavenging Internal Combustion Engine and Operating Method". Technical Field

[0002] The present invention relates to a large, low-speed, turbocharged, two-stroke, single-flow scavenging internal combustion engine having a crosshead and multiple cylinders, and a method of operating such an engine. Background Technology

[0003] Large, low-speed turbocharged two-stroke single-flow scavenging internal combustion engines with crossheads are typically used in the propulsion systems of large ships or as prime movers in power plants.

[0004] This type of modern engine is fully electronically controlled, meaning that during engine operation, the electronic control system can control both the fuel intake / injection and the opening and closing of the exhaust valves to ensure that the engine operates optimally under given operating conditions.

[0005] The engine is calibrated before leaving the factory to ensure that it meets all performance requirements, such as power, fuel efficiency, emissions, noise / vibration levels, and reliability.

[0006] Therefore, when an engine leaves the factory, it performs at its best and meets performance requirements. However, because the engine, or at least the engine cylinders, deviates from the factory specifications and requires recalibration, it wears and deteriorates over time.

[0007] Recently, there has been a need for large turbocharged two-stroke compression ignition engines capable of handling alternative fuels, such as natural gas, liquefied petroleum gas, methanol, coal slurry, water-oil mixtures, and petroleum coke.

[0008] Several of these alternative fuels have the potential to reduce costs and emissions.

[0009] Large ocean-going freighters are typically propelled by large, low-speed, single-flow scavenged, turbocharged, two-stroke internal combustion engines, making reliability paramount. The operation of these engines using alternative fuels is still relatively new, and the redundancy of gaseous fuel operation is at a lower level of reliability compared to operation using conventional fuels. When intentionally using gaseous fuels, the uptime of dual-fuel engines is reduced, thus lowering costs. For example, the redundancy is lower with gaseous fuel systems. If a fault is detected in one cylinder, the gaseous fuel supply to all cylinders is stopped. In conventional fuel (oil) mode, only the cylinder affected by the fault is stopped. Operation using conventional fuels ensures relevance. Therefore, it is important to be able to quickly switch from alternative fuels to conventional fuels, as operation using conventional fuels is considered a safe fallback measure.

[0010] Therefore, existing large, low-speed two-stroke diesel engines are all dual-fuel engines. These dual-fuel engines have a fuel system for operating with alternative fuels such as gaseous fuels and another fuel system for operating with conventional fuels such as fuel oil, allowing the engine to operate at full power when using only conventional fuels.

[0011] When problems arise while operating on alternative fuels, such as insufficient gas pressure when using gaseous fuels, it is essential to be able to quickly switch back to conventional fuels. It is also important to be able to quickly and easily switch back to alternative fuels in order to save costs and reduce emissions.

[0012] However, when the fuel type changes, the combustion process is no longer the same, and the engine must be recalibrated to adapt to operation with different fuels. For example, the timing and duration of fuel injection, the timing of exhaust valve closure, scavenging pressure, compression pressure, maximum (peak) cylinder pressure, and mean indicated pressure need to be adjusted to suit the type of fuel being used. This means that a new process balance must be achieved, especially since the characteristics (calorific value) of the large quantities of gaseous fuel delivered by a typical gaseous fuel system can exhibit significant fluctuations.

[0013] Known engine control systems cannot perform this recalibration satisfactorily without human intervention. They either take too long or lack sufficient precision to immediately reach the engine's optimal operating conditions after a fuel switch.

[0014] Furthermore, large, low-speed turbocharged two-stroke single-flow scavenging internal combustion engines are calibrated at the factory to ensure that the combustion process in each cylinder is performed according to design standards throughout the engine's operation. Before leaving the factory, the cylinders are balanced (load-balanced), meaning the maximum (peak) pressure or average indicated pressure (load) of each cylinder is as uniform as possible. Alternatively, instead of peak pressure, the average indicated pressure for each cylinder is kept as uniform as possible to ensure the best possible load balance.

[0015] However, after leaving the factory, wear and tear will have varying effects on the engine and each cylinder over time. During use, the combustion process in the cylinders deviates from factory specifications, and cylinder balance deteriorates. Over time, this development leads to reduced performance and increased emissions, which should be counteracted at some point by recalibrating the control system.

[0016] Known control systems for large two-stroke internal combustion engines require manual intervention for this recalibration. However, manual intervention requires expert skills because a change in one parameter, such as the closing angle of the exhaust valve, will affect the range of other parameters. Typically, engine operators lack the skills required to perform recalibrations involving manual intervention, and therefore, such recalibrations rarely occur. Some consequences of this lack of recalibration include increased fuel consumption and emissions.

[0017] Rolle S. and Wiesmann A. disclosed in Wärtsilä Technical Journal, in 2011, a combustion control and monitoring system for two-stroke engines, which provides a common load setpoint for all cylinders, measures cylinder pressure for each cylinder and adjusts fuel injection timing and exhaust valve closure accordingly. Summary of the Invention

[0018] In this context, the purpose of this application is to provide a large, low-speed turbocharged two-stroke single-flow scavenging internal combustion engine that overcomes or at least mitigates the aforementioned problems, as well as a method for operating such an engine.

[0019] According to the first aspect, this objective is achieved by providing a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine with a crosshead, the engine comprising:

[0020] Multiple cylinders, said cylinders having:

[0021] -Exhaust valve,

[0022] - An exhaust valve actuation system, used to actuate the exhaust valve.

[0023] - A fuel delivery system that delivers a predetermined amount of initial fuel to the relevant cylinder.

[0024] - A pressure sensor that generates a pressure signal for a specific cylinder, representing the pressure in the relevant cylinder.

[0025] An exhaust-driven turbocharger that pressurizes the scavenging air used in the cylinders.

[0026] The controller receives the following actual operating states of the engine or is configured to determine the following actual operating states of the engine:

[0027] A common torque signal representing the torque to be transmitted by the engine.

[0028] The common peak pressure signal represents the peak cylinder pressure to be achieved in the cylinder.

[0029] The common compression pressure signal represents the compression pressure to be achieved in the cylinder.

[0030] The controller receives pressure signals from specific cylinders.

[0031] in:

[0032] a) The controller is configured to: derive an actual torque signal of the specific cylinder, representing the torque transmitted by the relevant specific cylinder, from the pressure signal of the specific cylinder; adjust the common torque signal according to the deviation between the common torque signal and the actual torque signal of the specific cylinder to obtain the torque signal of the specific cylinder; and deliver a certain amount of fuel to the relevant specific cylinder according to the torque signal of the specific cylinder.

[0033] as well as

[0034] b) The controller is configured to: derive an actual peak pressure signal of the specific cylinder (1) representing the peak pressure in the relevant cylinder from the pressure signal of the specific cylinder; adjust the common peak pressure signal according to the deviation between the common peak pressure signal and the actual peak pressure signal of the specific cylinder to obtain the peak pressure signal of the specific cylinder; and determine the start time for delivering the specified amount of fuel to the relevant specific cylinder (1) based on the peak pressure signal of the specific cylinder.

[0035] as well as

[0036] c) The controller is configured to: derive an actual compression pressure signal of the specific cylinder from the pressure signal of the specific cylinder, representing the compression pressure in the relevant cylinder, adjust the common compression pressure signal according to the deviation between the common compression pressure signal and the actual compression pressure signal of the specific cylinder, so as to obtain the compression pressure signal of the specific cylinder; and determine the closing time of the exhaust valve of the relevant specific cylinder according to the compression pressure signal of the specific cylinder.

[0037] By adjusting the corresponding combustion process parameters (one or more) in a cylinder-specific manner—that is, by generating cylinder-specific torque signals, cylinder-specific feed pressure signals, and / or cylinder-specific compression pressure signals in the feedback loop—each cylinder can operate strictly according to factory specifications, even if engine wear and other factors alter the operating state of the relevant cylinder. Simultaneously, it enables control of the combustion process in each cylinder of the engine without considering the overall cylinder load balance or cylinder balancing. This method of engine control ensures that each cylinder operates at its optimal state without concern for cylinder balance (load balance).

[0038] In a possible implementation of the first aspect, the engine is fuel-driven, and the engine includes at least element a).

[0039] In a possible implementation of the first aspect, the engine is air-guided, and the engine includes at least element c).

[0040] In a possible implementation of the first aspect, the engine is partially fuel-driven and partially air-driven, and the engine includes at least element a) and element c).

[0041] In a possible implementation of the first aspect, the engine is a dual-fuel engine, wherein the fuel delivery system is configured to handle at least two different fuels, and each cylinder is provided with at least one fuel valve for delivering the first fuel and at least one fuel valve for delivering the second fuel.

[0042] In a possible implementation of the first aspect, the engine is fuel-guided when running on a first fuel and air-guided when running on a second fuel.

[0043] In a possible implementation of the first aspect, the controller receives a desired engine speed and a measured engine speed, wherein the controller includes a regulator configured to determine a fuel index signal based on the deviation between the desired engine speed and the measured engine speed.

[0044] In a possible implementation of the first aspect, the controller is configured to convert the fuel index signal into a common torque signal by applying the fuel index signal to a first predetermined graph.

[0045] In a possible implementation of the first aspect, the controller includes a power calculation module configured to calculate an engine load signal indicating engine load, the power calculation module preferably receiving a fuel index signal and a measured engine speed.

[0046] In a possible implementation of the first aspect, the controller is configured to:

[0047] - Determine the common peak pressure signal by applying the engine load signal to a second predetermined graph, and / or

[0048] - The common compression pressure is determined by applying the engine load signal to a third predetermined diagram.

[0049] In a possible implementation of the first aspect, the controller includes a fuel index signal to a distributed duration module, which is configured to convert the fuel index signal into a common fuel delivery duration signal.

[0050] In a possible implementation of the first aspect, the controller is configured to adjust the common fuel delivery duration signal based on the deviation between the common fuel delivery duration signal and the torque signal of a specific cylinder to obtain the fuel delivery duration signal of the specific cylinder.

[0051] In a possible implementation of the first aspect, the controller is configured to determine the injection distribution of a particular cylinder based on a torque signal of the particular cylinder or a fuel delivery duration signal of the particular cylinder, and wherein the fuel delivery system delivers a certain amount of fuel to the relevant particular cylinder by opening one or more fuel valves according to the injection distribution of the particular cylinder.

[0052] In a possible implementation of the first aspect, the fuel delivery system begins to deliver a certain amount of fuel to a specific cylinder by opening one or more fuel valves according to a timing determined by the controller.

[0053] In a possible implementation of the first aspect, the controller is configured to:

[0054] - When the adjustment of other cylinders is in the same direction, the amplitude of the adjustment of the common torque signal is limited to a first threshold, and wherein the controller is configured to limit the amplitude of the adjustment of the common torque signal to a second threshold when the adjustment of other cylinders is in the opposite direction.

[0055] and / or

[0056] - When the adjustment of other cylinders (1) is in the same direction, the amplitude of the adjustment of the common peak pressure signal is limited to a first threshold, and wherein the controller (55) is configured to limit the amplitude of the adjustment of the common peak pressure signal to a second threshold when the adjustment of other cylinders (1) is in the opposite direction.

[0057] and / or

[0058] - When the adjustment of other cylinders (1) is in the same direction, the amplitude of the adjustment of the common compression pressure signal is limited to a first threshold, and wherein the controller (55) is configured to limit the amplitude of the adjustment of the common compression pressure signal to a second threshold when the adjustment of other cylinders (1) is in the opposite direction.

[0059] In a possible implementation of the first aspect, the second threshold is lower than the first threshold.

[0060] In a possible implementation of the first aspect, the first predetermined drawing, the second predetermined drawing, and / or the third predetermined drawing are preferably pre-set at the engine factory based on testing of the relevant engine or the same or equivalent engine, and the first predetermined drawing, the second predetermined drawing, and / or the third predetermined drawing preferably include algorithms and / or tables.

[0061] In a possible implementation of the first aspect, the common torque signal corresponds to the average indicated cylinder pressure for all cylinders, and wherein the torque signal for a particular cylinder corresponds to the average indicated cylinder pressure for the relevant particular cylinder.

[0062] In a possible implementation of the first aspect, the controller includes a cylinder compensation module for each cylinder, the cylinder compensation module being configured to compensate for a common torque signal, a common peak pressure signal, and / or a common compression pressure signal of the associated cylinder.

[0063] In a possible implementation of the first aspect, the compensation module for a particular cylinder is either manually or automatically controlled.

[0064] In a possible implementation of the first aspect, the controller is configured to control the engine cylinders individually without taking into account cylinder balance.

[0065] In the possible implementation of the first aspect,

[0066] The controller is configured to continuously calculate the error value based on the difference between the torque of a specific cylinder and the actual torque of the specific cylinder, and, in the case of the engine having component a), apply a correction based on a proportional term and an integral term.

[0067] The controller is configured to continuously calculate the error value based on the difference between the peak pressure of a specific cylinder and the actual peak pressure of that specific cylinder, and, in the case of the engine having element b), apply a correction based on a proportional term and an integral term.

[0068] The controller is configured to continuously calculate the error value based on the difference between the compression pressure of a specific cylinder and the actual compression pressure of the specific cylinder, and, in the case of the engine having element c), apply correction based on proportional and integral terms.

[0069] In a possible implementation of the first aspect, the fuel delivery system is configured to deliver a quantity of first fuel and / or a quantity of second fuel to the relevant cylinder.

[0070] According to a second aspect, a method is provided for operating a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine with a crosshead, the engine comprising:

[0071] Multiple cylinders, said cylinders having:

[0072] -Exhaust valve,

[0073] - An exhaust valve actuation system, used to actuate the exhaust valve.

[0074] - A fuel delivery system that delivers a predetermined amount of initial fuel to the relevant cylinder.

[0075] - A pressure sensor that generates a pressure signal for a specific cylinder, representing the pressure in the relevant cylinder.

[0076] An exhaust-driven turbocharger that pressurizes scavenging air for use in the cylinders.

[0077] The method includes:

[0078] Closed-loop control is performed on at least one combustion process parameter of a cylinder in a cylinder-specific manner based on the pressure signal and setpoint of a specific cylinder. The setpoint of a specific cylinder is a compensation for the common setpoint of all cylinders.

[0079] By adjusting specific combustion process parameters (one or more) on a cylinder-specific basis—that is, generating cylinder-specific torque signals, cylinder-specific feed pressure signals, and / or cylinder-specific compression pressure signals in the feedback loop—each cylinder can operate strictly according to factory specifications, even if engine wear and other factors alter the operating state of the relevant cylinder. Simultaneously, it achieves control of the combustion process in each cylinder of the engine without considering the overall cylinder load balance or cylinder balancing. This method of engine control ensures that each cylinder operates at its optimal state without concern for cylinder balance (load balance).

[0080] In a possible implementation of the second aspect, the at least one combustion process parameter includes:

[0081] - Fuel quantity,

[0082] - Timing of fuel injection initiation, and / or

[0083] - When to close the exhaust valve.

[0084] In a possible implementation of the second aspect, closed-loop control is performed without considering maintaining cylinder balance.

[0085] In a possible implementation of the second aspect, closed-loop control applies corrections based on proportional and integral terms.

[0086] In a possible implementation of the second aspect, the common setpoint is:

[0087] - A common torque signal representing the torque to be transmitted by the engine, and / or

[0088] - A common peak pressure signal representing the peak cylinder pressure to be achieved in the cylinder, and / or

[0089] - This represents a common compression pressure signal that indicates the compression pressure to be achieved in the cylinder.

[0090] In a possible implementation of the second aspect, the closed-loop control uses the measured cylinder pressure of a specific cylinder as a reference value.

[0091] In a possible implementation of the second aspect, the average indicated cylinder pressure of a particular cylinder is derived from the measured cylinder pressure of that particular cylinder, and / or the peak pressure of that particular cylinder is derived from the measured cylinder pressure of that particular cylinder, and / or the compression pressure of that particular cylinder is derived from the measured pressure of that particular cylinder.

[0092] According to a third aspect, a method is provided for operating a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine with a crosshead, the engine comprising:

[0093] Multiple cylinders, said cylinders having:

[0094] -Exhaust valve,

[0095] - An exhaust valve actuation system, used to actuate the exhaust valve.

[0096] - A fuel delivery system that delivers a predetermined amount of initial fuel to the relevant cylinder.

[0097] - A pressure sensor that generates a pressure signal for a specific cylinder, representing the pressure in the relevant cylinder.

[0098] An exhaust-driven turbocharger that pressurizes the scavenging air used in the cylinders.

[0099] The controller receives the following actual operating states of the engine or is configured to determine the following actual operating states of the engine:

[0100] A common torque signal, which represents the torque to be transmitted by the engine.

[0101] The common peak pressure signal represents the peak cylinder pressure to be achieved in the cylinder.

[0102] The common compression pressure signal represents the compression pressure to be achieved in the cylinder.

[0103] The controller receives pressure signals from specific cylinders.

[0104] The method includes:

[0105] The torque signal of the actual specific cylinder, representing the torque transmitted by the relevant specific cylinder, is derived from the pressure signal of the specific cylinder. The common torque signal is then adjusted based on the deviation between the common torque signal and the actual specific cylinder torque signal to obtain the torque signal of the specific cylinder.

[0106] And deliver a certain amount of fuel to the relevant specific cylinder based on the torque signal of the specific cylinder, and / or

[0107] b) Derive the actual peak pressure signal of the specific cylinder, representing the peak pressure in the relevant cylinder, from the pressure signal of the specific cylinder. Adjust the common peak pressure signal according to the deviation between the common peak pressure signal and the actual peak pressure signal of the specific cylinder to obtain the peak pressure signal of the specific cylinder.

[0108] The timing for initiating the delivery of the specified amount of fuel is determined based on the peak pressure signal of a particular cylinder, and / or

[0109] c) Derive the actual compression pressure signal of the specific cylinder from the pressure signal of the specific cylinder, representing the compression pressure in the relevant cylinder; adjust the common compression pressure signal according to the deviation between the common compression pressure signal and the actual compression pressure signal of the specific cylinder to obtain the compression pressure signal of the specific cylinder; and

[0110] The timing of exhaust valve closure is determined based on the compression pressure signal of a specific cylinder.

[0111] According to the fourth aspect, a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine with a crosshead is provided, the engine comprising:

[0112] Multiple cylinders, said cylinders having:

[0113] -Exhaust valve,

[0114] - An exhaust valve actuation system, which is used to actuate the exhaust valve.

[0115] - A fuel delivery system, wherein the fuel delivery system is used to deliver a certain amount of first fuel to the relevant cylinder.

[0116] - A pressure sensor that generates a pressure signal for a specific cylinder, representing the pressure in the relevant cylinder.

[0117] An exhaust-driven turbocharger that pressurizes the scavenging air used in the cylinders.

[0118] A controller configured to perform closed-loop control of one or more combustion process parameters of a cylinder in a cylinder-specific manner based on the following:

[0119] - Pressure signal for a specific cylinder, and

[0120] o For the common setpoint of all cylinders, or

[0121] The setpoint of a specific cylinder is a compensation for a specific cylinder based on a common setpoint.

[0122] According to a fifth aspect, a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine with a crosshead is provided, the engine comprising:

[0123] - Multiple cylinders, said cylinders having:

[0124] Exhaust valve,

[0125] An exhaust valve actuation system, used to actuate the exhaust valve.

[0126] A fuel delivery system (30) is used to deliver a certain amount of first fuel to the relevant cylinder.

[0127] - An exhaust-driven turbocharger that pressurizes the scavenging air used in the cylinders.

[0128] - A controller configured to control at least one of the following in a cylinder-specific manner: combustion process parameters (one or more), fuel quantity, timing of fuel injection initiation, and timing of exhaust valve closure.

[0129] The controller (55) is configured to:

[0130] Depending on the engine's operating status, the combustion process parameters of cylinder (1) are controlled by cyclically adjusting the common setpoint or the setpoint of a specific cylinder of the combustion process parameters (one or more) in a cylinder-specific manner.

[0131] The average value of the adjustments to the combustion process parameters (one or more) of a specific cylinder is calculated.

[0132] The adjustment of a specific cylinder in a cycle of combustion process parameters (one or more) is limited to the average of the calculated adjustments of the relevant combustion process parameters plus or minus the maximum predetermined deviation.

[0133] By providing a limiter function that ensures that adjustments, especially for specific cylinders, do not exceed the range, sufficient flexibility can be provided to accommodate large adjustments that occur under normal circumstances, while suppressing large adjustments caused by errors, thereby ensuring that damage or interruption of operation is avoided.

[0134] According to a possible implementation of the fifth aspect, the controller is configured to limit the range to the average value of the calculated adjustments of the relevant combustion process parameters plus or minus a maximum predetermined deviation, and to limit the adjustment of a particular cylinder in a cycle of the combustion process parameters (one or more) to the adjustment within the range.

[0135] According to a possible implementation of the fifth aspect, the range is a range with a first positive range and a second negative range relative to the average value of the adjusted relevant combustion process parameters.

[0136] According to the possible implementation of the fifth aspect, this range is specific to the combustion process parameters.

[0137] According to a possible implementation of the fifth aspect, the positive range has a first predetermined amplitude, and the negative range has a second predetermined amplitude, wherein the first predetermined amplitude need not be the same as the second predetermined amplitude.

[0138] According to a possible implementation of the fifth aspect, the controller is configured to calculate the average value of the adjustment of a particular cylinder for the combustion process parameter (one or more) for one or more cycles of cyclic adjustment of the relevant combustion process parameter.

[0139] According to the possible implementation of the fifth aspect, the adjustment of the combustion process parameters (one or more) is an adjustment for a single cycle.

[0140] According to a possible implementation of the fifth aspect, the at least one combustion process parameter includes:

[0141] - Fuel quantity,

[0142] - Timing of fuel injection initiation, and / or

[0143] - When to close the exhaust valve.

[0144] According to a possible implementation of the fifth aspect, the setpoint for a specific cylinder for combustion process parameters (one or more) is a compensation for a common setpoint for combustion process parameters (one or more).

[0145] According to the possible implementation scheme of the fifth aspect, the engine operating state is one or more of the following: engine speed, engine load, cylinder peak pressure, cylinder combustion pressure, cylinder average indicated pressure, scavenging pressure, fuel type, ambient humidity, and ambient temperature.

[0146] According to a sixth aspect, a method is provided for operating a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine with a crosshead, the engine comprising:

[0147] - Multiple cylinders, said cylinders having:

[0148] Exhaust valve,

[0149] An exhaust valve actuation system, used to actuate the exhaust valve.

[0150] A fuel delivery system is used to deliver a certain amount of first fuel to the relevant cylinder.

[0151] - An exhaust-driven turbocharger that pressurizes the scavenging air used in the cylinders.

[0152] The method includes:

[0153] At least one of the following parameters—combustion process parameters (one or more), fuel quantity, timing of fuel injection initiation, and timing of exhaust valve closure—is controlled in a cylinder-specific manner.

[0154] Depending on the engine's operating status, the combustion process parameters (one or more) of cylinder (1) are controlled by cyclically adjusting the common setpoint or the setpoint of a specific cylinder in a cylinder-specific manner.

[0155] Calculate the average value of the adjustments made to a specific cylinder for one or more combustion process parameters.

[0156] The range around the calculated average value of the adjustments for one or more combustion process parameters is determined, and

[0157] The adjustment of a specific cylinder in a cycle of combustion process parameters (one or more) is limited to the average of the calculated adjustments of the relevant combustion process parameters plus or minus the maximum predetermined deviation.

[0158] Other purposes, features, advantages, and characteristics of the fuel valve and engine according to this disclosure will become apparent from the detailed description. Attached Figure Description

[0159] In the following detailed sections of this specification, the invention will be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which:

[0160] Figure 1 This is a front view of a large two-stroke diesel engine according to an example embodiment.

[0161] Figure 2 yes Figure 1 A side view of a large two-stroke engine.

[0162] Figure 3 It is based on Figure 1 A schematic diagram of a large two-stroke engine.

[0163] Figure 4 It is used for Figure 1 A schematic diagram of an implementation method for an engine controller, and

[0164] Figure 5 It is used for Figure 1 A schematic diagram of another embodiment of the engine controller, and

[0165] Figure 6 It is used for Figure 1 A schematic diagram of another embodiment of the engine controller. Detailed Implementation

[0166] In the following detailed description, compression ignition internal combustion engines will be described with reference to a large two-stroke low-speed turbocharged internal combustion (diesel) engine in an example embodiment. Figure 1 , Figure 2 and Figure 3 A large, low-speed turbocharged two-stroke diesel engine with a crankshaft 8 and a crosshead 9 is shown. Figure 3 A large, low-speed turbocharged two-stroke diesel engine with an intake and exhaust system is shown. In this example embodiment, the engine has six cylinders 1 arranged in a row. Large, low-speed turbocharged two-stroke diesel engines typically have between four and fourteen cylinders arranged in a row, carried by an engine frame 11. This engine can be used, for example, as the main engine of an ocean-going vessel or as a stationary engine to power generators in a power plant. The total output of the engine can be, for example, in the range of 1,000 kW to 110,000 kW.

[0167] In this example embodiment, the engine is a two-stroke, single-flow scavenging diesel (compression ignition) engine or an Otto (spark ignition) engine, having a scavenging port 18 in the lower region of cylinder 1 and a central exhaust valve 4 at the top of cylinder 1. Scavenging air is delivered from the scavenging receiver 2 to the scavenging port 18 of each cylinder 1. The piston 10 in cylinder 1 compresses the scavenging air, fuel is injected from fuel valves 50, 51 in cylinder head 22, and then combusted to produce exhaust gas. When exhaust valve 4 is open, exhaust gas flows through the exhaust pipe associated with cylinder 1 to exhaust receiver 3, and forward through the first exhaust pipe 19 to the turbine 6 of turbocharger 5. Exhaust gas from turbine 6 flows through the second exhaust pipe via economizer 20 to outlet 21 and into the atmosphere. Turbine 6 drives compressor 7, which is supplied with fresh air via intake port 12, via a shaft. The compressor 7 delivers pressurized scavenging air to the scavenging air pipe 13, which leads to the scavenging air receiver 2.

[0168] The scavenging gas in pipe 13 passes through an intercooler 14 for cooling the scavenging gas. In the example embodiment, the scavenging gas leaves the compressor at approximately 200°C and is cooled to a temperature between 36°C and 80°C by the intercooler.

[0169] When the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging receiver 2, i.e., under low or partial engine load, the cooled scavenging air passes through an auxiliary fan 16 driven by an electric motor 17, which pressurizes the scavenging airflow. Under higher engine load, the turbocharger compressor 7 delivers sufficient compressed scavenging air, and then the auxiliary fan 16 is bypassed via a check valve 15.

[0170] The piston is connected to the crosshead 9 via a piston rod. The crosshead 9 is connected to the crankshaft 8 via a connecting rod. The rotational speed and position of the crankshaft 8 are measured by a sensor 40. The engine speed signal measured by the sensor 40 is transmitted to the controller 55, for example, via a signal line.

[0171] Each cylinder 1 is equipped with an exhaust valve 4, and each cylinder 1 is also equipped with a pressure sensor 42 and two or more fuel valves 50. The pressure signal of a specific cylinder from the pressure sensor 42 is sent to the controller 55.

[0172] In one embodiment, the engine is a dual-fuel engine, and in this embodiment, two or more fuel valves 50 are dedicated to a first fuel, while two or more fuel valves 50 are dedicated to a second fuel. Alternatively, two or more fuel valves may be shared by both fuels.

[0173] Fuel valve 50 is controlled by controller 55, which determines, for example, when and for how long the fuel valve opens, and in some embodiments, also determines the opening distribution of fuel valve 50. Fuel valve 50 is part of fuel supply system 30. The signals used to open and close fuel valve 50 can be fluid or hydraulic signals. In embodiments where the signals used to open and close fuel valve are fluid signals such as hydraulic signals, controller 55 can send electronic signals to an electronically controlled valve or pump, from which the hydraulic signals are sent to fuel valve 55.

[0174] In one embodiment, the fuel supply system 30 is configured to supply at least two different fuels. In another embodiment, one of the fuels is fuel oil, such as heavy fuel oil or methanol. In yet another embodiment, one of the fuels is a gaseous fuel such as petroleum gas or natural gas. In yet another embodiment, the gaseous fuel enters or is injected into the cylinder in a gaseous state. In yet another embodiment, the gaseous fuel enters or is injected into the cylinder in a liquid state.

[0175] In this implementation, the engine is a fuel-guided engine. In a fuel-guided or gas-guided combustion process, the amount of fuel to be metered is determined based on the operating point of the internal combustion engine and a specified target value for the engine's speed and / or power. Fuel-guided combustion is particularly applicable during the variable-speed operation of an internal combustion engine, in isolated operation, during engine startup, or when the engine is idling. The deployed engine controller includes a power controller and / or a speed controller. Engines specifically designed for diesel engine processes are fuel-guided engines, regardless of whether the fuel is liquid or gaseous. Typically, the fuel is injected shortly after top dead center (TDC) and ignited immediately upon injection. Therefore, the amount of fuel to be injected is a key control parameter of a fuel-guided engine.

[0176] In this implementation, the engine is an air-guided engine. To avoid knocking problems (premature combustion) or specific scavenging pressures, especially specific compression pressures, the amount of fuel to be metered is determined during air-guided combustion, for example, based on the operating point of the internal combustion engine and a specifyable target value for the fuel-air ratio. Therefore, the deployed engine control unit typically includes a compression pressure controller. Engines specifically operating according to the Otto process are air-guided engines, regardless of the type of fuel. Therefore, compressed air pressure is the primary control parameter for air-guided engines.

[0177] In this implementation, the engine is a combination of an intake port and a fuel-guided engine. An example of such an engine is one in which a first quantity of fuel is introduced into the combustion chamber before the compression stroke, and a second quantity of fuel is injected near top dead center (TDC). The injection of the second quantity of fuel initiates the ignition of both the second and first quantities of fuel in the combustion chamber. In large two-stroke engines, the injection near TDC typically occurs shortly after TDC. In this engine, both the amount of fuel to be injected and the compression pressure are key control parameters, and the importance of each parameter can depend on engine load and speed.

[0178] In this implementation, the internal combustion engine is a dual-fuel engine, which is fuel-driven when running on a first fuel and air-driven when running on a second fuel.

[0179] Each exhaust valve 4 is provided with an exhaust valve actuator 46. In an embodiment, the exhaust valve actuator 46 is a hydraulic actuator, which is commanded by an electronic signal from a controller 55.

[0180] Another combustion process parameter in cylinder 1 is controlled by controller 55. These parameters include, for example, at least one of the following: fuel quantity, timing of fuel injection initiation, and timing of exhaust valve closure. The fuel quantity parameter relates to the contribution of the relevant cylinder 1 to the torque transmitted by the engine. The timing of fuel injection initiation relates to the peak pressure in the relevant cylinder (this is particularly relevant to engines operating on diesel principles, and less relevant to engines operating on the Otto principle, where fuel is introduced rather than injected). The timing of exhaust valve closure relates to the combustion pressure in the relevant cylinder 1.

[0181] Figure 4 A first embodiment of the controller 55 is shown. In this embodiment, the controller 55 includes an engine controller and a plurality of cylinder controllers.

[0182] The controller 55 receives, for example, a speed setting from the cab, i.e., the desired engine speed. The controller 55 receives engine speed signals from sensor 40 and compares the desired engine speed with the measured engine speed to obtain a speed deviation signal. The controller 55 includes a regulator fed with the speed deviation signal. This regulator is configured to determine a fuel index based on the deviation between the desired engine speed and the measured engine speed; that is, the regulator is configured to determine the fuel index based on the speed deviation signal. The fuel index signal is a signal indicating the amount of fuel to be injected to achieve the desired engine speed. The amount of fuel to be injected is directly related to the amount of torque to be transmitted by the engine.

[0183] The controller 55 includes a specification for a common torque signal module configured to convert a fuel specification into a common torque signal by applying a fuel specification to a first predetermined graph. The common indicated torque / specification can be considered proportional to the common average indicated pressure.

[0184] In this document, "common" means: applies to all cylinders.

[0185] The first predetermined graph is established through testing, such as testing conducted on a test bench at a factory where the engine is developed and / or manufactured. In an implementation, the first predetermined graph includes a table or algorithm that correlates fuel parameters with commonly indicated torque.

[0186] The cylinder controller is associated with each cylinder in cylinder 1. A common torque signal is sent to each cylinder controller in the cylinder controller.

[0187] The controller 55 includes a power calculation module (load calculation) configured to calculate an engine load signal indicating engine load. In one embodiment, the engine load signal is a representation of the actual engine load relative to the maximum engine load, such as the maximum continuous rating. The power calculation module receives an index signal and a measured engine speed. In one embodiment, the load calculation module multiplies the engine speed by a fuel index and multiplies the result by a predetermined factor established by test or empirical values ​​to obtain a percentage of the engine load, i.e., the maximum continuous rating.

[0188] The controller 55 includes an engine operating mode module configured to determine a common peak pressure signal by applying an engine load signal to a second predetermined graph, and the engine operating mode module is also configured to determine a common compression pressure by applying the engine load signal to a third predetermined graph.

[0189] The second and third predetermined graphs are established based on tests, such as those conducted on test benches at a factory where the engine is developed and / or manufactured. In one embodiment, the second predetermined graph includes a table or algorithm that correlates peak pressure with engine load, and in another embodiment, the third predetermined graph includes a table or algorithm that correlates compression pressure with engine load. The second and third graphs may take into account many other parameters such as ambient pressure, ambient temperature, and engine speed, and may include compensations such as friction losses.

[0190] The common peak pressure signal and the common compression pressure signal are sent to all cylinder controllers.

[0191] Each cylinder controller receives a specific measured cylinder pressure from the pressure sensor 42 dedicated to the cylinder 1 for that cylinder controller.

[0192] The cylinder controller is configured to calculate the maximum pressure, compression pressure, and average indicated pressure of the actual specific cylinder based on the pressure signal received from the pressure sensor 42 of the associated cylinder 1. The average indicated pressure of the specific cylinder is hereinafter referred to as the torque of the actual specific cylinder.

[0193] Preferably, the actual pressure value of a particular cylinder is determined by, for example, the arithmetic mean of multiple consecutive pressure measurements over 5 to 50 engine cycles, preferably about 10 engine cycles, and particularly preferably the median.

[0194] In order to obtain better signal quality and thus higher control performance, the pressure signal of a specific cylinder is the first pressure signal of the specific cylinder obtained by temporary filtering measurement after 5 to 50 engine cycles, preferably 7 to 15 combustion cycles.

[0195] Therefore, the actual pressure of a specific cylinder is the result of a statistical evaluation of the pressure measurement performed by the pressure sensor 42 of the relevant cylinder 1.

[0196] The cylinder controller is configured to adjust the common torque signal based on the deviation between the common torque signal and the actual torque signal of a specific cylinder to obtain the torque signal of the specific cylinder. Therefore, the cylinder controller continuously (or intermittently) calculates the error value based on the difference between the torque of the specific cylinder and the actual torque of the specific cylinder, and applies corrections based on proportional and integral terms (PI regulator) to obtain the torque signal of the specific cylinder and form a closed-loop control for the associated specific cylinder 1.

[0197] In one embodiment, the controller 55 receives adjustments for the common torque, the common peak pressure, and / or the common compression pressure. In this embodiment, the controller 55 is configured to determine an average for the adjustment of the common torque for all cylinders, an average or mean for the adjustment of the common peak pressure for all cylinders, and / or an average or mean for the adjustment of the compression pressure for the cylinders.

[0198] In this embodiment, controller 55 is configured to allow each cylinder controller to set the maximum adjustment range of the torque, peak pressure, and / or compression pressure of a particular cylinder within a window defined by an adjustment of a corresponding average value plus or minus a predetermined amount. For example, the adjustment window is the calculated average value plus or minus 5 bar. In this example, when the average adjustment of the peak pressure of a particular cylinder for all cylinders is +2 bar, each cylinder controller will be allowed to adjust the peak pressure of the particular cylinder between -3 bar and +7 bar.

[0199] The limiter restricts the maximum correction to the common torque signal. If the correction of the common torque signal points in the same direction for all cylinders 1, the limiter allows the maximum correction to reach a first threshold. If the correction of the common torque signal does not point in the same direction for all cylinders 1, the limiter allows the maximum correction to reach a second threshold, which is lower than the first threshold. Therefore, erroneous signals are prevented from compromising system stability, and if all cylinders 1 have the same configuration, a larger correction is allowed.

[0200] Therefore, the controller 55 calculates the average value of the adjustment of a specific cylinder for the torque signal of all cylinders, and limits the adjustment of a specific cylinder in the cycle of the torque signal to the calculated average value of the adjusted torque signal plus or minus a maximum predetermined deviation.

[0201] The controller 55 is configured to limit the range to the average value of the calculated torque signal adjustment plus or minus a maximum predetermined deviation, and is configured to limit the adjustment of a particular cylinder in the torque signal cycle to adjustment within the range. This range is a range having a first positive range and a second negative range relative to the average value of the calculated torque signal adjustment. The range is specific to the torque signal and other combustion process parameters (pressure and combustion pressure). The positive range has a first predetermined amplitude, and the negative range has a second predetermined amplitude. These amplitudes can be determined, for example, at the factory through test runs. The range should be large enough to accommodate the maximum adjustment that would typically occur, but small enough to exclude adjustments that might be caused by errors, such as erroneous sensor signals.

[0202] The controller 55 is configured to calculate the average value of the cylinder's adjustment to the torque signal for a specific cylinder in one or more cycles of cyclic adjustment for the torque signal. In an embodiment, the adjustment of the combustion process parameters (one or more) is an adjustment for a single cycle.

[0203] The injection distribution module converts the torque signal of a specific cylinder into a fuel valve distribution signal for that specific cylinder. The injection distribution module associates the torque signal of a specific cylinder with the injection distribution by applying the specific torque signal to a fourth predetermined diagram. The fourth diagram may include an algorithm and / or lookup table established based on testing. The fuel valve distribution signal for a specific cylinder is sent to the fuel valve 50 of the relevant cylinder, and the fuel valve 50 is indicated according to the distribution of when the fuel valve 50 should be open and closed, i.e., the fuel valve opening duration and distribution shape. The fuel valve 50 delivers the required amount of fuel to the relevant specific cylinder 1 in response to the fuel valve distribution signal from the cylinder controller associated with the relevant cylinder 1.

[0204] The cylinder controller is configured to adjust the common peak pressure signal based on the deviation between the common peak pressure signal and the actual peak pressure signal of a specific cylinder to obtain the peak pressure signal of the specific cylinder. Therefore, the cylinder controller continuously (or intermittently) calculates the error value based on the difference between the torque of the specific cylinder and the pressure of the actual specific cylinder, and applies corrections based on proportional and integral terms (PI regulator) to obtain the peak pressure signal of the specific cylinder and form closed-loop control for the associated specific cylinder 1.

[0205] In the same manner, as described above regarding the torque signal, the limiter for the peak pressure signal limits the maximum correction to the common peak pressure signal. If the correction of the common peak pressure signal points in the same direction for all cylinders 1, the limiter allows the maximum correction to reach a first threshold. If the correction of the common peak pressure signal does not point in the same direction for all cylinders 1, the limiter allows the maximum correction to reach a second threshold, which is lower than the first threshold. Therefore, erroneous signals are prevented from disrupting system stability, and if all cylinders 1 have the same configuration, a larger correction is allowed.

[0206] The peak pressure module converts the peak pressure signal of a specific cylinder into a fuel injection timing signal for that specific cylinder. At this point, the peak pressure module applies the peak pressure signal of the specific cylinder to a fifth predetermined graph. The fifth predetermined graph may include an algorithm and / or lookup table that associates pressure with the start of fuel entry / injection. The algorithm and / or lookup table for the fifth predetermined graph can be established through testing.

[0207] A fuel injection timing signal for a specific cylinder is sent to the fuel valve 50 of the associated cylinder 1, and the fuel valve 50 is instructed when it should begin to open (i.e., the time (angle) at which fuel begins to enter / inject). In response to the injection timing signal from the cylinder controller associated with the associated cylinder 1, the fuel valve 50 of the associated cylinder 1 begins to allow the amount of fuel from the specific cylinder to enter / inject into the associated specific cylinder 1.

[0208] The cylinder controller is configured to adjust the common compression pressure signal based on the deviation between the common compression pressure signal and the actual compression pressure signal of a specific cylinder to obtain the compression pressure signal of the specific cylinder. Therefore, the cylinder controller continuously (or intermittently) calculates the error value based on the difference between the compression signal of the specific cylinder and the actual compression pressure of the specific cylinder, and applies corrections based on proportional and integral terms (PI regulator) to obtain the compression pressure signal of the specific cylinder, thus forming a closed-loop control for the associated specific cylinder 1.

[0209] In the same manner, as described above regarding the torque signal and peak pressure signal, the limiter for the compression pressure signal limits the maximum correction to the common compression pressure signal. If the correction of the common compression pressure signal points in the same direction for all cylinders 1, the limiter allows the maximum correction to reach a first threshold. If the correction of the common compression pressure signal does not point in the same direction for all cylinders 1, the limiter allows the maximum correction to reach a second threshold, which is lower than the first threshold. Therefore, erroneous signals are prevented from disrupting system stability, and if all cylinders 1 have the same configuration, a larger correction is allowed.

[0210] The compression pressure module converts the compression pressure signal of a specific cylinder into a signal indicating when the exhaust valve of that specific cylinder will close. At this point, the compression pressure module applies the compression pressure signal of the specific cylinder to a sixth predetermined diagram. The sixth predetermined diagram may include an algorithm and / or lookup table that correlates the compression pressure with the closing timing of the exhaust valve 4. The algorithm and / or lookup table for the sixth predetermined diagram can be established through testing.

[0211] A signal indicating when the exhaust valve of a specific cylinder should close is sent to the fuel valve 50 of the associated cylinder 1, and the exhaust valve actuator 46 is instructed when the exhaust valve 4 should close, i.e., at the time (angle) of closing the exhaust valve 4. In response to the exhaust valve closing signal from the cylinder controller associated with the associated cylinder 1, the exhaust valve actuator 46 of the associated cylinder 1 closes.

[0212] In this implementation, the torque signal (mean indicated pressure) adjustment, peak pressure adjustment, and combustion pressure adjustment for a specific cylinder are sent back to the controller 55, and an average "mean indicated pressure adjustment," average peak pressure adjustment, and average combustion pressure adjustment are calculated. This adjustment is performed cyclically, for example, for every single, two, five, or ten engine revolutions. The average value of the combustion process parameters for all cylinders is also calculated cyclically, preferably at the same cycle frequency as the adjustment cycle. The controller 55 sets a cylinder-specific adjustment limit for the corresponding combustion process parameter relative to the calculated average value of the relevant combustion process parameters. This limit can be in the form of adding or subtracting a maximum predetermined deviation from the calculated average value. The predetermined positive deviation can differ from the predetermined negative deviation. Thus, a range is formed around the calculated average value of the relevant process parameters. The predetermined positive and negative deviations are process parameter-specific. Integrator saturation will be variable, allowing for larger adjustments when the average adjustments of torque, peak pressure, and combustion pressure are large.

[0213] The cylinder controller is configured to control each cylinder 1 of the engine individually, without considering cylinder balancing; that is, there is no cylinder balancing. Therefore, each cylinder 1 operates according to design specifications by providing a specific cylinder feedback loop control that provides the average indicated pressure (torque) for a particular cylinder, and / or providing a specific cylinder feedback loop control that provides the peak pressure for a particular cylinder, and / or providing a specific cylinder feedback loop control that provides the compression pressure for a particular cylinder. Since all cylinders 1 will operate according to design specifications, cylinder balancing is unnecessary. This is particularly advantageous for dual-fuel engines after changing fuel from one type to another. In conventional engines, such fuel changes require manual recalibration to ensure optimal engine operation after a fuel change. Using the controller according to this document, no manual recalibration is required after a fuel change. Peak pressure and torque are especially critical during the transition from fuel oil to a secondary fuel (e.g., gas), and this will be automatically ensured / regulated by this controller.

[0214] However, in certain situations, it may be necessary to operate one or more cylinders that differ from their design specifications. For example, when cylinder 1 is in a state where a significant risk of cylinder liner wear (adhesion) is determined, cylinder liner wear (adhesion) is sometimes caused by insufficient cylinder lubrication. It may be necessary to reduce the load on cylinders that indicate wear is occurring or will soon occur if the load is not reduced.

[0215] Therefore, in Figure 5 In the embodiment of the controller shown in the implementation, each cylinder controller includes a cylinder compensation module for a specific cylinder of each cylinder 1. In this embodiment, for simplicity, structures and features identical or similar to those previously described or shown herein are indicated by the same reference numerals as previously used. Except for the addition of a specific cylinder compensation module, this embodiment of controller 55 is similar to... Figure 4 The implementation methods are basically the same.

[0216] A cylinder-specific compensation module is configured to compensate for common torque signals, common peak pressure signals, and / or common compression pressure signals relative to the relevant cylinder 1. For example, compensation can be automatically introduced based on a signal from a sensor inducing the cylinder controller or the controller to introduce compensation settings for the specific cylinder 1, or it can be introduced manually. For example, knock detection within a specific cylinder can be performed by a sensor. In response to such a knock sensor, the compression pressure of that specific cylinder is reduced by the controller 55 to lower the temperature in the combustion chamber, thereby reducing the risk of knock. Therefore, cylinder-specific compensation is introduced for the relevant cylinder. Furthermore, in an embodiment, the controller 55 is configured to increase the air-fuel ratio by reducing the fuel quantity through cylinder-specific compensation for the amount of fuel to be injected.

[0217] Therefore, the cylinder compensation module outputs the torque setpoint, peak pressure setpoint, and compression pressure setpoint for a specific cylinder. This is consistent with the above... Figure 4 In the same manner as the implementation method, the set point of the specific cylinder is adjusted according to the difference between the torque of the specific cylinder, the peak pressure of the specific cylinder and the compression pressure of the specific cylinder, so as to obtain the torque of the specific cylinder, the peak pressure of the specific cylinder and the compression pressure of the specific cylinder respectively.

[0218] Figure 6 Another embodiment of the controller 55 is shown. In this embodiment, for simplicity, structures and features that are the same or similar to those previously described or shown herein are indicated by the same reference numerals used previously. Except for adding a fuel index to the distributed duration module, this embodiment of the controller 55 is similar to... Figure 5 The implementation methods are basically the same. The fuel index of the distributed duration module is configured to convert the fuel index signal into a common distributed duration signal.

[0219] Each cylinder controller receives a common fuel delivery duration signal. The cylinder controller adjusts the common fuel delivery duration signal based on the deviation between the common fuel delivery duration signal and the torque signal of a specific cylinder to obtain the fuel distribution duration signal for that specific cylinder.

[0220] The addition of a common distribution duration signal makes the engine more robust to fluctuations in fuel quality. This is especially true for gaseous fuels, whose properties tend to vary; for example, the LCV (lower calorific value) of gaseous fuels can vary by as much as 30% to 50%.

[0221] In one implementation, the common torque signal corresponds to the average indicated cylinder pressure of all cylinders, and wherein the torque signal of a particular cylinder corresponds to the average indicated cylinder pressure of the relevant particular cylinder.

[0222] Various aspects and embodiments have been described in conjunction with the various implementations described herein. However, those skilled in the art who study the accompanying drawings, disclosure, and appended claims will understand and implement other variations of the disclosed embodiments. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single processor, controller, or other unit may perform the functions of several items recited in the claims. The fact that certain measures are recited in different dependent claims does not mean that combinations of these measures cannot be advantageously used.

[0223] The reference numerals used in the claims should not be construed as limiting the scope. Unless otherwise stated, the drawings (e.g., shading lines, arrangement of parts, scale, extent, etc.) are intended to be read in conjunction with the specification and should be considered as part of the entire written description of this disclosure.

Claims

1. A method of operating a large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine having a crosshead (9), said engine comprising: A plurality of cylinders (1), said cylinder (1) having: -Exhaust valve (4), - An exhaust valve actuation system (46) for actuating the exhaust valve (4). - A fuel delivery system (30) for delivering a certain amount of first fuel to the associated cylinder (1), - Pressure sensor (42), the pressure sensor (42) being used to generate a pressure signal for a specific cylinder representing the pressure in the associated cylinder (1), An exhaust-driven turbocharger (5) pressurizes the scavenging air for the cylinder (1). A controller (55) includes a common setpoint for all cylinders (1) and a setpoint for a specific cylinder, wherein the setpoint for the specific cylinder is a compensation for the common setpoint for all cylinders (1). The method includes: Based on the pressure signal of the specific cylinder and the set point of the specific cylinder, which serves as compensation for the common set point of all cylinders (1), at least one combustion process parameter of the cylinder (1) is controlled in a cylinder-specific manner in a closed-loop manner.

2. The method according to claim 1, wherein, At least one combustion process parameter includes: - Fuel quantity, - Timing of fuel injection initiation, and / or - When to close the exhaust valve.

3. The method according to claim 1 or 2, wherein, The closed-loop control is performed without considering maintaining cylinder balance.

4. The method according to claim 1 or 2, wherein, The closed-loop control applies corrections based on proportional and integral terms.

5. The method according to claim 1 or 2, wherein, The common setting point is: - A common torque signal representing the torque to be transmitted by the engine, and / or - A common peak pressure signal representing the peak cylinder pressure to be achieved in the cylinder, and / or - This represents a common compression pressure signal indicating the compression pressure to be achieved in the cylinder.

6. The method according to claim 1 or 2, wherein, The closed-loop control uses the measured cylinder pressure of a specific cylinder as a reference value.

7. The method according to claim 6, wherein, The average indicated cylinder pressure of the specific cylinder is derived from the measured cylinder pressure of the specific cylinder, and / or wherein, The peak pressure of the particular cylinder is derived from the measured cylinder pressure of the particular cylinder, and / or the compression pressure of the particular cylinder is derived from the measured cylinder pressure of the particular cylinder.

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