Large low speed turbocharged two stroke single flow scavenging internal combustion engine and method of operation

Abstract

The present invention provides a large low speed turbocharged two stroke single flow scavenging internal combustion engine and a method of operating the same, the engine having a plurality of cylinders (1) and an exhaust driven turbocharger (5) for pressurizing scavenging air for the cylinders (1), the cylinders 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 certain amount of first fuel to the associated cylinder (1), and a method of operating the same, the method comprising: closed loop control of the fuel amount, the timing of fuel admission / injection start and / or the timing of exhaust valve closing for the cylinders based on the cylinder-specific pressure signal and based on a common set point for all cylinders or based on a set point for each specific cylinder, the set point for each specific cylinder being an adjustment of the common set point for each specific cylinder.

Description

Technical Field

[0001] The present invention relates to a large, low speed, turbocharged, two-stroke, uniflow scavenged internal combustion engine having a crosshead and having a plurality of cylinders, and a method of operating such an engine. Background Art

[0002] Large, low-speed, turbocharged, two-stroke, single-flow scavenged internal combustion engines with a crosshead are often used in propulsion systems for large ships or as prime movers for power plants.

[0003] Modern engines of this type are fully electronically controlled, ie both the admission / injection of fuel and the opening and closing of the exhaust valves can be controlled by an electronic control system during engine operation to ensure that the engine operates optimally under given operating conditions.

[0004] The engine is calibrated before leaving the factory to ensure it meets all performance requirements, such as power, fuel efficiency, emissions, noise / vibration levels and reliability.

[0005] Thus, when leaving the factory, the engine performs optimally and meets performance requirements. However, over time, wear and tear occurs as the engine, or at least the cylinders of the engine, deviate from factory specifications, ie, require recalibration.

[0006] Recently, there has been a need for large turbocharged two-stroke compression ignition engines that are able to handle alternative types of fuels, such as natural gas, petroleum gas, methanol, coal sludge, water-oil mixtures, petroleum coke, and the like.

[0007] Several of these alternative fuels have the potential to reduce costs and emissions.

[0008] Large, low-speed, single-flow, scavenged, turbocharged, two-stroke internal combustion engines are often used to propel large ocean-going cargo vessels, so reliability is of paramount importance. The operation of these engines with alternative fuels is still a relatively recent development and the redundancy of operation with gaseous fuels is at a lower reliability level than when operating with conventional fuels. When gaseous fuels are used intentionally, the uptime of the dual-fuel engine is reduced, which reduces costs. For example, with gaseous fuel systems, redundancy is lower. If a fault is detected on 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 with conventional fuel ensures relevance. It is therefore important to be able to quickly switch from alternative fuels to conventional fuels, as operation with conventional fuels is considered a safe fallback measure.

[0009] Therefore, existing large slow-speed two-stroke diesel engines are dual-fuel engines having a fuel system for running on an alternative fuel such as, for example, gaseous fuel and another fuel system for running on a conventional fuel such as, for example, fuel oil, so that the engine can run at full power using only conventional fuel.

[0010] In the event of problems with operation on alternative fuels, such as insufficient gas pressure when operating on gaseous fuels, it is essential to be able to quickly switch from operation on alternative fuels to operation on conventional fuels. It is also important to be able to quickly and easily switch from conventional fuels back to alternative fuels in order to save costs and reduce emissions.

[0011] However, when the fuel type is changed, the combustion process is no longer the same and the engine must be recalibrated for operation with a different fuel, e.g. the timing and duration of fuel injection, timing of exhaust valve closing, control of scavenging pressure, compression pressure, cylinder maximum (peak) pressure and indicated mean pressure need to be adjusted to the type of fuel used. This means that a new process balance must be achieved, especially since the properties (heating value) of the bulk gaseous fuel delivered by a typical gaseous fuel system can show large fluctuations.

[0012] Known engine control systems are not able to perform such recalibration in a satisfactory manner without human intervention. Known control systems either take too long or are not accurate enough to achieve the optimal operating conditions of the engine immediately after a fuel switch.

[0013] Furthermore, large low-speed turbocharged two-stroke single-flow scavenging internal combustion engines are calibrated before leaving the factory so that the combustion process in each of the cylinders of the engine is performed according to the design standard in the entire operating state of the engine. Before leaving the factory, the cylinders are balanced (load balanced), that is, the cylinder maximum (peak) pressure or average indicated pressure (load) of each cylinder is as uniform as possible. Alternatively, instead of the peak pressure, the average indicated pressure for each cylinder is kept as uniform as possible to ensure the best possible load balance.

[0014] However, after the factory, over time, wear and tear will affect the engine and each of the cylinders differently. During use, the combustion process in the cylinders deviates from the factory specifications and the cylinder balance deteriorates. Over time, such developments lead to reduced performance and increased emissions, which should be counteracted at some point in time by recalibrating the control system.

[0015] Known control systems for large two-stroke internal combustion engines require manual intervention to perform such recalibration. However, manual intervention requires expert skills, since a change in one of the parameters, such as the closing angle of the exhaust valve, will affect other parameter ranges. Typically, the engine operator does not have the skills required to perform a recalibration involving manual intervention, and therefore, such a recalibration does not actually take place. Some of the consequences of this lack of recalibration are increased fuel consumption and emissions.

[0016] Rolle S., Wiesmann A., Combustion control and monitoring for two-stroke engines, Wärtsilä Technology Magazine, 2011, discloses an engine with a closed-loop fuel control system in which a common load set point is provided for all cylinders, cylinder pressure is measured for each cylinder separately and fuel injection timing and exhaust valve closing are adjusted accordingly. Summary of the invention

[0017] Against this background, it is an object of the present application to provide a large, low speed, turbocharged, two-stroke, uniflow scavenged internal combustion engine and a method of operating such an engine which overcomes or at least alleviates the above mentioned problems.

[0018] According to a first aspect, the object is achieved by providing a large, low-speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead, the engine comprising:

[0019] A plurality of cylinders, each cylinder having:

[0020] - Exhaust valve,

[0021] an exhaust valve actuation system for actuating the exhaust valve,

[0022] a fuel delivery system for delivering a quantity of a first fuel to an associated cylinder,

[0023] a pressure sensor for generating a cylinder-specific pressure signal representative of the pressure in the associated cylinder,

[0024] an exhaust-driven turbocharger that pressurizes scavenging air for the cylinders,

[0025] A controller receives the following actual operating state of the engine or is configured to determine the following actual operating state of the engine:

[0026] a common torque signal representative of the torque to be delivered by the engine,

[0027] a common peak pressure signal representing the peak cylinder pressure to be achieved in the cylinder,

[0028] a common compression pressure signal representing the compression pressure to be achieved in the cylinder,

[0029] The controller receives the pressure signal of a specific cylinder.

[0030] in:

[0031] a) the controller is configured to: derive an actual cylinder-specific torque signal representing the torque delivered by the associated specific cylinder from the cylinder-specific pressure signal; and adjust the common torque signal according to a deviation of the common torque signal from the actual cylinder-specific torque signal to obtain the cylinder-specific torque signal; and deliver a certain amount of fuel to the associated specific cylinder according to the cylinder-specific torque signal,

[0032] as well as

[0033] b) the controller is configured to: derive an actual specific cylinder peak pressure signal representing the peak pressure in the relevant cylinder (1) from the specific cylinder pressure signal, adjust the common peak pressure signal according to the deviation between the common peak pressure signal and the actual specific cylinder peak pressure signal to obtain the specific cylinder peak pressure signal; and determine the start time of delivering the certain amount of fuel to the relevant specific cylinder (1) according to the specific cylinder peak pressure signal,

[0034] as well as

[0035] c) The controller is configured to: derive an actual specific cylinder compression pressure signal representing the compression pressure in the relevant cylinder from the pressure signal of the specific cylinder, to adjust the common compression pressure signal according to the deviation between the common compression pressure signal and the actual specific cylinder compression pressure signal, to obtain the specific cylinder compression pressure signal; and to determine the closing time of the exhaust valve of the relevant specific cylinder according to the specific cylinder compression pressure signal.

[0036] By adjusting the corresponding combustion process parameter(s) in a cylinder-specific manner, i.e. generating a cylinder-specific torque signal, a cylinder-specific feed pressure signal and / or a cylinder-specific compression pressure signal in a feedback loop, it is possible to achieve that each cylinder operates strictly in accordance with factory specifications, even if wear and tear of the engine or other factors change the operating state of the relevant cylinder. At the same time, it is achieved that the combustion process of the cylinders in the engine is controlled without taking into account the load balance of the cylinders or the cylinders of the entire engine. This way of controlling the engine ensures that each cylinder is in an optimal operating state without having to worry about cylinder balance (load balance).

[0037] In a possible implementation of the first aspect, the engine is fuel-guided and the engine comprises at least element a).

[0038] In a possible implementation of the first aspect, the engine is air-guided and the engine comprises at least element c).

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

[0040] In a possible implementation of the first aspect, the engine is a dual fuel engine and wherein the fuel delivery system is configured to handle at least two different fuels and the cylinders are each provided with at least one fuel valve for delivering the first fuel and at least one fuel valve for delivering the second fuel.

[0041] In a possible implementation of the first aspect, the engine is fuel-guided when operating on the first fuel and air-guided when operating on the second fuel.

[0042] In a possible implementation of the first aspect, the controller receives a desired engine speed and receives a measured engine speed, and wherein the controller includes a regulator configured to determine the fuel indicator signal based on a deviation of the desired engine speed from the measured engine speed.

[0043] In a possible implementation of the first aspect, the controller is configured to convert the fuel index signal into the common torque signal by applying the fuel index signal to a first predetermined map.

[0044] In a possible implementation of the first aspect, the controller comprises a power calculation module configured to calculate an engine load signal indicative of engine load, the power calculation module preferably receiving a fuel indicator signal and a measured engine speed.

[0045] In a possible implementation of the first aspect, the controller is configured to:

[0046] - determining the common peak pressure signal by applying the engine load signal to a second predetermined map, and / or

[0047] - Determining the common compression pressure by applying the engine load signal to a third predetermined map.

[0048] In a possible implementation of the first aspect, the controller includes a fuel indicator signal to profile duration module configured to convert the fuel indicator signal to a common fuel delivery duration signal.

[0049] In a possible implementation of the first aspect, the controller is configured to adjust the common fuel delivery duration signal according to a deviation of the common fuel delivery duration signal and the cylinder-specific torque signal to obtain the cylinder-specific fuel delivery duration signal.

[0050] In a possible implementation of the first aspect, the controller is configured to determine an injection distribution of a specific cylinder based on a torque signal of the specific cylinder or based on a fuel delivery duration signal of the specific cylinder, and wherein the fuel delivery system delivers the amount of fuel to the relevant specific cylinder by opening one or more fuel valves based on the injection distribution of the specific cylinder.

[0051] In a possible implementation of the first aspect, the fuel delivery system starts delivering the amount of fuel to the associated specific cylinder by opening one or more fuel valves according to a start timing of delivery of the amount of fuel determined by the controller.

[0052] In a possible implementation of the first aspect, the controller is configured to:

[0053] - limiting the amplitude of the adjustment of the common torque signal to a first threshold when the adjustment for the other cylinders is in the same direction, 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 for the other cylinders is in the opposite direction,

[0054] and / or

[0055] - limiting the amplitude of the adjustment of the common peak pressure signal to a first threshold value when the adjustment for the other cylinders (1) is in the same direction, and wherein the controller (55) is configured to limit the amplitude of the adjustment of the common peak pressure signal to a second threshold value when the adjustment for the other cylinders (1) is in the opposite direction,

[0056] and / or

[0057] - when the adjustments for the other cylinders (1) are in the same direction, the amplitude of the adjustments of the common compression pressure signal is limited to a first threshold value, and wherein the controller (55) is configured to limit the amplitude of the adjustments of the common compression pressure signal to a second threshold value when the adjustments for the other cylinders (1) are in the opposite direction.

[0058] In a possible implementation of the first aspect, the second threshold is lower than the first threshold.

[0059] In a possible implementation scheme of the first aspect, the first predetermined map, the second predetermined map and / or the third predetermined map are preferably pre-set in the engine factory based on tests of related engines or the same or equivalent engines, and the first predetermined map, the second predetermined map and / or the third predetermined map preferably include algorithms and / or tables.

[0060] In a possible implementation of the first aspect, the common torque signal corresponds to an average indicated cylinder pressure for all cylinders and wherein the cylinder-specific torque signal corresponds to an average indicated cylinder pressure for the associated specific cylinder.

[0061] In a possible implementation of the first aspect, the controller includes a cylinder-specific cylinder compensation module for each cylinder, and the cylinder-specific cylinder compensation module is configured to compensate for the common torque signal, common peak pressure signal and / or common compression pressure signal of the relevant specific cylinder.

[0062] In a possible implementation of the first aspect, the cylinder-specific compensation module is manually controlled or automatically controlled.

[0063] In a possible implementation of the first aspect, the controller is configured to control the cylinders of the engine individually without considering cylinder balance.

[0064] In a possible implementation of the first aspect,

[0065] the controller being configured to continuously calculate an error value based on the difference between the cylinder-specific torque and the actual cylinder-specific torque and to apply a correction based on a proportional term and an integral term in the case of an engine having element a),

[0066] the controller being configured to continuously calculate an error value based on the difference between the cylinder-specific peak pressure and the actual cylinder-specific peak pressure and, in the case of an engine having element b), apply a correction based on a proportional term and an integral term,

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

[0068] In a possible implementation of the first aspect, the fuel delivery system is configured for delivering an amount of the first fuel and / or an amount of the second fuel to the associated cylinder.

[0069] According to a second aspect, there is provided a method of operating a large, low speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead, the engine comprising:

[0070] A plurality of cylinders, each cylinder having:

[0071] - Exhaust valve,

[0072] an exhaust valve actuation system for actuating the exhaust valve,

[0073] a fuel delivery system for delivering a quantity of a first fuel to an associated cylinder,

[0074] a pressure sensor for generating a cylinder-specific pressure signal representative of the pressure in the associated cylinder,

[0075] an exhaust-driven turbocharger that pressurizes scavenging air for the cylinders,

[0076] The method includes:

[0077] At least one combustion process parameter of a cylinder is closed-loop controlled in a cylinder-specific manner based on the cylinder-specific pressure signal and a cylinder-specific setpoint that is a cylinder-specific offset to a common setpoint for all cylinders.

[0078] By adjusting the corresponding combustion process parameter(s) in a cylinder-specific manner, i.e. generating a cylinder-specific torque signal, a cylinder-specific feed pressure signal and / or a cylinder-specific compression pressure signal in a feedback loop, it is possible to achieve that each cylinder operates strictly in accordance with factory specifications, even if wear and tear of the engine or other factors change the operating state of the relevant cylinder. At the same time, control of the combustion process of the cylinders in the engine is achieved without taking into account the load balance of the cylinders or the cylinders of the entire engine. This way of controlling the engine ensures that each cylinder is in optimal operating condition without having to worry about cylinder balance (load balance).

[0079] In a possible implementation of the second aspect, the at least one combustion process parameter comprises:

[0080] - amount of fuel,

[0081] - the timing of the start of fuel injection, and / or

[0082] -Timing of exhaust valve closing.

[0083] In a possible implementation of the second aspect, closed-loop control is instead performed without regard to maintaining cylinder balance.

[0084] In a possible implementation of the second aspect, the closed loop control applies a correction based on a proportional term and an integral term.

[0085] In a possible implementation of the second aspect, the common set point is:

[0086] - a common torque signal representative of the torque to be delivered by the engine, and / or

[0087] - a common peak pressure signal representative of the peak cylinder pressure to be achieved in the cylinder, and / or

[0088] - a common compression pressure signal representative of the compression pressure to be achieved in the cylinder.

[0089] In a possible implementation of the second aspect, the closed-loop control uses a measured cylinder pressure of a specific cylinder as a reference value.

[0090] In a possible implementation of the second aspect, an average indicated cylinder pressure of the specific cylinder is derived from the measured cylinder pressure of the specific cylinder, and / or wherein a peak pressure of the specific cylinder is derived from the measured cylinder pressure of the specific cylinder, and / or wherein a compression pressure of the specific cylinder is derived from the measured pressure of the specific cylinder.

[0091] According to a third aspect, there is provided a method of operating a large, low speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead, the engine comprising:

[0092] A plurality of cylinders, each cylinder having:

[0093] - Exhaust valve,

[0094] an exhaust valve actuation system for actuating the exhaust valve,

[0095] a fuel delivery system for delivering a quantity of a first fuel to an associated cylinder,

[0096] a pressure sensor for generating a cylinder-specific pressure signal representative of the pressure in the associated cylinder,

[0097] an exhaust-driven turbocharger that pressurizes scavenging air for the cylinders,

[0098] A controller receives the following actual operating state of the engine or is configured to determine the following actual operating state of the engine:

[0099] a common torque signal representing the torque to be delivered by the engine,

[0100] a common peak pressure signal representing a peak cylinder pressure to be achieved in the cylinder,

[0101] a common compression pressure signal representing the compression pressure to be achieved in the cylinder,

[0102] A controller receives a pressure signal from a specific cylinder.

[0103] The method includes:

[0104] deriving an actual cylinder-specific torque signal representing the torque delivered by the associated specific cylinder from the cylinder-specific pressure signal, and adjusting the common torque signal according to a deviation of the common torque signal from the actual cylinder-specific torque signal to obtain the cylinder-specific torque signal,

[0105] and delivering a certain amount of fuel to the relevant specific cylinder according to the torque signal of the specific cylinder,

[0106] and / or

[0107] b) deriving an actual cylinder-specific peak pressure signal representing the peak pressure in the associated cylinder from the cylinder-specific pressure signal, adjusting the common peak pressure signal according to a deviation between the common peak pressure signal and the actual cylinder-specific peak pressure signal to obtain the cylinder-specific peak pressure signal, and

[0108] determining the timing of starting to deliver the certain amount of fuel according to the peak pressure signal of the specific cylinder,

[0109] and / or

[0110] c) deriving an actual cylinder-specific compression pressure signal representing the compression pressure in the associated cylinder from the cylinder-specific pressure signal, adjusting the common compression pressure signal according to a deviation of the common compression pressure signal from the actual cylinder-specific compression pressure signal to obtain the cylinder-specific compression pressure signal, and

[0111] The timing of exhaust valve closing is determined based on the compression pressure signal for a specific cylinder.

[0112] According to a fourth aspect, there is provided a large, low speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead, the engine comprising:

[0113] A plurality of cylinders, each cylinder having:

[0114] - Exhaust valve,

[0115] an exhaust valve actuation system for actuating the exhaust valve,

[0116] a fuel delivery system for delivering a quantity of a first fuel to an associated cylinder,

[0117] a pressure sensor for generating a cylinder-specific pressure signal representative of the pressure in the associated cylinder,

[0118] an exhaust-driven turbocharger that pressurizes scavenging air for the cylinders,

[0119] A controller configured to perform closed-loop control of one or more combustion process parameters of the cylinder in a cylinder-specific manner based on:

[0120] - the pressure signal of a specific cylinder, and

[0121] oa common set point for all cylinders, or

[0122] oCylinder-specific setpoints. The cylinder-specific setpoint is a cylinder-specific offset of the common setpoint.

[0123] According to a fifth aspect, there is provided a large, low speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead, the engine comprising:

[0124] - a plurality of cylinders, each cylinder having:

[0125] Exhaust valve,

[0126] an exhaust valve actuation system, the exhaust valve actuation system being used to actuate the exhaust valve,

[0127] a fuel delivery system (30) for delivering a quantity of a first fuel to an associated cylinder,

[0128] an exhaust-gas-driven turbocharger which pressurizes the scavenging air for the cylinders,

[0129] a controller configured to control at least one of the combustion process parameter(s), the fuel quantity, the timing of the start of fuel injection and the timing of exhaust valve closing in a cylinder-specific manner,

[0130] The controller (55) is configured to:

[0131] The combustion process parameters of the cylinders (1) are controlled individually by adjusting a common set point or a cylinder-specific set point of the combustion process parameter(s) in a cyclical, cylinder-specific manner, depending on the operating state of the engine,

[0132] calculating a cylinder-specific adjusted average value of the combustion process parameter(s) of the cylinder,

[0133] The cylinder-specific adjustments in a cycle of the combustion process parameter(s) are limited to a calculated average of the adjustments of the associated combustion process parameter plus or minus a maximum predetermined deviation.

[0134] By providing a limiter function which ensures that adjustment of a particular cylinder in particular is not out of range, it can be ensured that sufficient flexibility is provided to accommodate large adjustments that normally occur, while large adjustments due to errors are suppressed, thereby ensuring that damage or interrupted operation is avoided.

[0135] According to a possible implementation scheme of the fifth aspect, the controller is configured to limit the interval 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 adjustments of a specific cylinder in a cycle of the combustion process parameter (one or more) to adjustments within the interval.

[0136] According to a possible implementation of the fifth aspect, the interval is a range having a first range in a positive direction and a second range in a negative direction relative to the calculated adjusted mean value of the relevant combustion process parameter.

[0137] According to a possible implementation of the fifth aspect, the interval is combustion process parameter specific.

[0138] According to a possible implementation of the fifth aspect, the positive range has a first predetermined amplitude, and wherein the negative range has a second predetermined amplitude, the first predetermined amplitude not necessarily being the same as the second predetermined amplitude.

[0139] According to a possible implementation of the fifth aspect, the controller is configured to calculate a cylinder average value of a cylinder-specific adjustment of the combustion process parameter(s) for one or more cycles of the cyclic adjustment of the relevant combustion process parameter.

[0140] According to a possible implementation of the fifth aspect, the adjustment of the combustion process parameter(s) is an adjustment for a single cycle.

[0141] According to a possible implementation of the fifth aspect, the at least one combustion process parameter comprises:

[0142] - amount of fuel,

[0143] - the timing of the start of fuel injection, and / or

[0144] -Timing of exhaust valve closing.

[0145] According to a possible implementation of the fifth aspect, the cylinder-specific setpoint for the combustion process parameter(s) is a compensation for the common setpoint for the combustion process parameter(s).

[0146] According to a possible implementation scheme of the fifth aspect, the operating state of the engine 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.

[0147] According to a sixth aspect, there is provided a method of operating a large, low speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead, the engine comprising:

[0148] - a plurality of cylinders, each cylinder having:

[0149] Exhaust valve,

[0150] an exhaust valve actuation system, the exhaust valve actuation system being used to actuate the exhaust valve,

[0151] a fuel delivery system for delivering a quantity of a first fuel to an associated cylinder,

[0152] an exhaust-gas-driven turbocharger which pressurizes the scavenging air for the cylinders,

[0153] The method includes:

[0154] controlling at least one of the combustion process parameter(s), fuel quantity, timing of start of fuel injection and timing of exhaust valve closing in a cylinder-specific manner,

[0155] Depending on the operating state of the engine, the combustion process parameter(s) of the cylinder(s) are controlled individually by adjusting a common set point or a cylinder-specific set point of the combustion process parameter(s) in a cyclical, cylinder-specific manner,

[0156] calculating a cylinder-specific adjusted average for the combustion process parameter(s),

[0157] determining an interval around the calculated average value adjusted for the combustion process parameter(s), and

[0158] The cylinder-specific adjustments of the combustion process parameter(s) in a cycle are limited to a calculated average of the adjustments of the associated combustion process parameter plus or minus a maximum predetermined deviation.

[0159] Other objects, features, advantages and properties of the fuel valve and engine according to the present disclosure will become apparent from the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0160] In the following detailed portion of the specification, the invention will be explained in more detail with reference to example embodiments shown in the accompanying drawings, in which:

[0161] Figure 1 is a front view of a large two-stroke diesel engine according to an example embodiment,

[0162] Figure 2 yes Figure 1 Side view of a large two-stroke engine.

[0163] Figure 3 is based on Figure 1 Schematic diagram of a large two-stroke engine.

[0164] Figure 4 is used for Figure 1 A schematic diagram of an embodiment of a controller of an engine, and

[0165] Figure 5 is used for Figure 1 A schematic diagram of another embodiment of a controller of an engine, and

[0166] Figure 6 is used for Figure 1 Schematic diagram of another embodiment of a controller for an engine. DETAILED DESCRIPTION

[0167] In the following detailed description, a compression ignition internal combustion engine 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 is shown having a crankshaft 8 and a crosshead 9 . Figure 3 A large, low-speed, turbocharged, two-stroke diesel engine with an intake system and an 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. The engine may, for example, be used as a main engine for an ocean-going vessel or as a stationary engine for operating a generator in a power station. The total output of the engine may, for example, be in the range of 1,000 kW to 110,000 kW.

[0168] In this example embodiment, the engine is a two-stroke single-flow scavenging type diesel (compression ignition) engine or Otto (spark ignition) engine having a scavenging port 18 at the lower region of the cylinder 1 and a central exhaust valve 4 at the top of the cylinder 1. The scavenging air is delivered from the scavenging air receiver 2 to the scavenging port 18 of each cylinder 1. The piston 10 in the cylinder 1 compresses the scavenging air, and the fuel is injected from the fuel valves 50, 51 in the cylinder head 22, then burns, and produces exhaust gas. When the exhaust valve 4 is opened, the exhaust gas flows through the exhaust pipe associated with the cylinder 1 to the exhaust gas receiver 3, and forwards through the first exhaust pipe 19 to the turbine 6 of the turbocharger 5, and the exhaust gas flows from the turbine 6 through the second exhaust pipe via the economizer 20 to the outlet 21 and flows into the atmosphere. The turbine 6 drives the compressor 7 supplied with fresh air via the intake port 12 through the shaft. The compressor 7 delivers pressurized purge air to a purge air duct 13 which leads to the purge air receiver 2 .

[0169] The purge gas in duct 13 passes through an intercooler 14 for cooling the purge gas. In an example embodiment, the purge gas leaves the compressor at approximately 200°C and is cooled to a temperature between 36°C and 80°C by the intercooler.

[0170] When the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging air receiver 2, i.e. at low or partial load of the engine, the cooled scavenging air passes via an auxiliary fan 16 driven by an electric motor 17, which pressurizes the scavenging air flow. At higher engine loads, the turbocharger compressor 7 delivers sufficient compressed scavenging air, and the auxiliary fan 16 is then bypassed via the non-return valve 15.

[0171] The piston is coupled to a crosshead 9 via a piston rod. The crosshead 9 is connected to a 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 sent to a controller 55, for example, via a signal line.

[0172] Each cylinder 1 is provided with an exhaust valve 4, and each cylinder 1 is provided with a pressure sensor 42 and two or more fuel valves 50. A cylinder-specific pressure signal of the pressure sensor 42 is sent to a controller 55.

[0173] In an embodiment, the engine is a dual fuel engine and in this embodiment, two or more fuel valves 50 are dedicated to the first fuel and two or more fuel valves 50 are dedicated to the second fuel. Alternatively, two or more fuel valves are shared by both fuels.

[0174] The fuel valve 50 is controlled by a controller 55, for example, the controller 55 determines when the fuel valve is opened and how long the fuel valve is opened, and in an embodiment, the controller 55 also determines the opening profile of the fuel valve 50. The fuel valve 50 is part of the fuel supply system 30. The signal for opening and closing the fuel valve 50 can be a fluid signal or a hydraulic signal. In an embodiment where the signal for opening and closing the fuel valve is a fluid signal such as a hydraulic signal, the controller 55 can send an electronic signal to an electronically controlled valve or pump, and the hydraulic signal is sent from the electronically controlled valve or pump to the fuel valve 55.

[0175] In an embodiment, the fuel supply system 30 is configured to be able to supply at least two different fuels. In an embodiment, one of the two fuels is fuel oil, such as fuel oil or heavy fuel oil or methanol. In an embodiment, one of the two fuels is a gaseous fuel such as petroleum gas or natural gas. In an embodiment, the gaseous fuel enters or is injected into the cylinder in a gaseous state. In another embodiment, the gaseous fuel enters or is injected into the cylinder in a liquid state.

[0176] In an embodiment, 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 predeterminable target value for the speed and / or power of the internal combustion engine. The fuel-guided combustion process is particularly used during variable speed operation of the internal combustion engine, in an isolated internal combustion engine, during engine start-up or when the internal combustion engine is idling. The deployed engine controller includes a power controller and / or a speed controller. An engine that operates specifically according to a diesel engine process is a fuel-guided engine, regardless of whether the fuel is a liquid fuel or a gaseous fuel. Typically, the fuel is injected shortly after the top dead center (TDC) and is ignited immediately upon injection. Therefore, the amount of fuel to be injected is the main control parameter of a fuel-guided engine.

[0177] In an embodiment, the engine is an air-guided engine. In order to avoid knock problems (premature combustion) or a specific scavenging pressure, in particular a specific compression pressure, the amount of fuel to be metered is determined in an air-guided combustion process, for example as a function of the operating point of the internal combustion engine and a predeterminable target value for the fuel-air ratio. Therefore, the deployed engine control device usually includes a compression pressure controller. Engines that are operated exclusively according to the Otto process are air-guided engines, regardless of the type of fuel. Therefore, the compressed air pressure is the main control parameter of air-guided engines.

[0178] In an embodiment, the engine is a combination of a port and fuel guided engine. An example of such an engine is an engine in which a first amount of fuel is admitted to the combustion chamber prior to the compression stroke, while an additional second amount of fuel is injected near top dead center (TDC). The injection of the second amount of fuel initiates ignition of both the second amount of fuel and the first amount of fuel in the combustion chamber. In large two-stroke engines, the injection near TDC typically occurs shortly after TDC. In such an engine, both the amount of fuel to be injected and the compression pressure are major control parameters, and the importance of each parameter may depend on the engine load and speed.

[0179] In an embodiment, the internal combustion engine is a dual fuel engine and is fuel directed when operating on a first fuel and air directed when operating on a second fuel.

[0180] 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 .

[0181] A further combustion process parameter of the combustion process in cylinder 1 is controlled by the controller 55. The combustion process parameter is, for example, at least one of the fuel quantity, the timing of the start of fuel admission / injection and the timing of exhaust valve closing. The combustion process parameter fuel quantity is related to the contribution of the relevant cylinder 1 to the torque delivered by the engine. The combustion process parameter of the timing of the start of fuel injection is related to the peak pressure in the relevant cylinder (this applies in particular to engines operating according to the diesel principle, but less so to engines operating according to the Otto principle, in which the fuel is admitted instead of being injected). The combustion process parameter of the timing of exhaust valve closing is related to the combustion pressure of the relevant cylinder 1.

[0182] Figure 4 A first embodiment of the controller 55 is shown. In the embodiment, the controller 55 includes an engine controller and a plurality of cylinder controllers.

[0183] The controller 55 receives a speed setting, i.e. a desired engine speed, for example, from the cab. The controller 55 receives an engine speed signal from the sensor 40, and the controller 55 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. The regulator is configured to determine a fuel index based on a deviation between the desired engine speed and the measured engine speed, i.e. 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 admitted / injected to achieve the desired engine speed. The amount of fuel to be injected is directly related to the amount of torque to be delivered by the engine.

[0184] The controller 55 includes an index to a common torque signal module configured to convert the fuel index to a common torque signal by applying the fuel index to a first predetermined map.The common indicated torque / index may be considered to be proportional to the common indicated mean pressure.

[0185] "Common" in this document means: applies to all cylinders.

[0186] The first predetermined map is established by tests, for example carried out on a test bench at a factory where the engine is developed and / or manufactured. In an embodiment, the first predetermined map comprises a table or algorithm relating fuel indicators to a common indicated torque.

[0187] A cylinder controller is associated with each of the cylinders in cylinder 1. A common torque signal is sent to each of the cylinder controllers.

[0188] The controller 55 includes a power calculation module (load calculation) configured to calculate an engine load signal indicative of the engine load. In an embodiment, the engine load signal is a representation of the actual engine load relative to a maximum engine load, such as a maximum continuous rating. The power calculation module receives the index signal and a measured engine speed. In an embodiment, the load calculation module multiplies the engine speed by the fuel index and multiplies the result by a predetermined factor that has been established by testing or empirical values ​​to derive a relative engine load, i.e., a percentage of the maximum continuous rating.

[0189] The controller 55 includes an engine operating mode module configured to determine the common peak pressure signal by applying the engine load signal to the second predetermined map, and the engine operating mode module configured to determine the common compression pressure by applying the engine load signal to the third predetermined map.

[0190] The second and third predetermined maps are established based on tests, for example, tests conducted on a test bench at a factory where the engine is developed and / or manufactured. In an embodiment, the second predetermined map comprises a table or algorithm relating peak pressure to engine load, and in an embodiment, the third predetermined map comprises a table or algorithm relating compression pressure to engine load. The second and third maps may take into account many other parameters such as ambient pressure, ambient temperature and engine speed, and may include compensation for, for example, friction losses.

[0191] A common peak pressure signal and a common compression pressure signal are sent to all cylinder controllers.

[0192] Each cylinder controller receives a specific measured cylinder pressure from the pressure sensor 42 of the cylinder 1 to which the associated cylinder controller is dedicated.

[0193] The cylinder controller is configured to calculate the actual cylinder-specific maximum pressure, the actual cylinder-specific compression pressure, and the actual cylinder-specific average indicated pressure based on the cylinder-specific pressure signal received from the pressure sensor 42 of the associated cylinder 1. The cylinder-specific average indicated pressure is hereinafter referred to as the actual cylinder-specific torque.

[0194] Preferably, the actual pressure value for a specific cylinder is determined from an arithmetic mean, particularly preferably a median, of a plurality of consecutive pressure measurements, for example over between 5 and 50 engine cycles, preferably approximately 10 engine cycles.

[0195] To achieve better signal quality and thus higher control performance, the cylinder-specific pressure signal of the cylinder is a temporarily filtered measured cylinder-specific first pressure signal obtained over 5 to 50 engine cycles, preferably 7 to 15 combustion cycles.

[0196] The actual cylinder-specific pressure is therefore the result of a statistical evaluation of the pressure measurements made by the pressure sensor 42 of the associated cylinder 1 .

[0197] The cylinder controller is configured to adjust the common torque signal according to the deviation between the common torque signal and the actual specific cylinder torque signal to obtain the specific cylinder torque signal. Therefore, the cylinder controller continuously (or intermittently) calculates the error value according to the difference between the specific cylinder torque and the actual specific cylinder torque, and applies correction based on the proportional term and the integral term (PI regulator) to obtain the specific cylinder torque signal and form a closed-loop control for the relevant specific cylinder 1.

[0198] In an embodiment, the controller 55 receives an adjustment of the common torque, an adjustment of the common peak pressure, and / or an adjustment of 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 of the cylinders.

[0199] In this embodiment, the controller 55 is configured to allow each cylinder controller to set the range of maximum adjustment of the torque of a specific cylinder, the peak pressure of a specific cylinder and / or the compression pressure of a specific cylinder within a window defined by the corresponding average value plus or minus an adjustment of a predetermined amount. For example, the adjustment window is plus or minus 5 bar of the calculated average value. In this example, when the average value of the adjustment of the peak pressure of a specific cylinder for all cylinders is positive 2 bar, each cylinder controller will be allowed to adjust the peak pressure adjustment of the specific cylinder between negative 3 bar and positive 7 bar.

[0200] The limiter limits 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. Thus, false signals are avoided from destabilizing the system and larger corrections are allowed if all cylinders 1 have the same deployment.

[0201] Therefore, the controller 55 calculates an average of the cylinder-specific adjustments to the torque signals for all cylinders and limits the cylinder-specific adjustments in a cycle of the torque signal to the calculated average of the adjusted torque signals plus or minus a maximum predetermined deviation.

[0202] The controller 55 is configured to define an interval as the average value of the calculated adjustments of the torque signal plus or minus a maximum predetermined deviation, and is configured to limit adjustments of a particular cylinder in a torque signal cycle to adjustments within the interval. The interval is a range having a first range in a positive direction and a second range in a negative direction relative to the average value of the calculated adjustments of the torque signal. The interval is specific to the torque signal and other combustion process parameters (pressure and combustion pressure). The positive range has a first predetermined amplitude, and wherein the negative range has a second predetermined amplitude. These amplitudes can be determined, for example, at the factory through test runs. The interval should be large enough to accommodate the maximum adjustment that will normally occur, but small enough to exclude adjustments that may be caused by errors, such as, for example, erroneous sensor signals.

[0203] The controller 55 is configured to calculate a cylinder-specific average of the adjustments to the torque signal for one or more cycles of the cyclic adjustment of the torque signal. In an embodiment, the adjustment of the combustion process parameter(s) is an adjustment for a single cycle.

[0204] The injection distribution module converts the torque signal of the specific cylinder into a fuel valve distribution signal for the specific cylinder. The injection distribution module associates the torque signal of the specific cylinder with the injection distribution by applying the specific torque signal to a fourth predetermined map. The fourth map may include an algorithm and / or a lookup table that has been established based on testing. The fuel valve distribution signal for the specific cylinder is sent to the fuel valve 50 of the relevant cylinder, and the fuel valve 50 is instructed according to the distribution that the fuel valve 50 should be opened and closed, that is, the fuel valve opening duration and the distribution shape. The fuel valve 50 delivers the fuel amount of the specific cylinder to the relevant specific cylinder 1 in response to the fuel valve distribution signal of the cylinder controller associated with the relevant cylinder 1.

[0205] The cylinder controller is configured to adjust the common peak pressure signal according to the deviation between the common peak pressure signal and the peak pressure signal of the actual specific cylinder to obtain the peak pressure signal of the specific cylinder. Therefore, the cylinder controller continuously (or intermittently) calculates the error value according to the difference between the torque of the specific cylinder and the pressure of the actual specific cylinder, and applies correction based on the proportional term and the integral term (PI regulator) to obtain the peak pressure signal of the specific cylinder and form a closed-loop control for the relevant specific cylinder 1.

[0206] In the same way, as described above for 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. Thus, erroneous signals are avoided from destabilizing the system, and larger corrections are allowed if all cylinders 1 have the same deployment.

[0207] The peak pressure module converts the peak pressure signal for the specific cylinder into a fuel injection timing signal for the specific cylinder. To this end, the peak pressure module applies the peak pressure signal for the specific cylinder to a fifth predetermined map. The fifth predetermined map may include an algorithm and / or a lookup table that correlates pressure to the start of fuel admission / injection. The algorithm and / or the lookup table of the fifth predetermined map may be established through testing.

[0208] The fuel injection timing signal of the specific cylinder is sent to the fuel valve 50 of the relevant cylinder 1, and indicates to the fuel valve 50 when the fuel valve should start to open (i.e., the time (angle) to start the fuel admission / injection). In response to the injection timing signal of the cylinder controller associated with the relevant cylinder 1, the fuel valve 50 of the relevant cylinder 1 starts to allow the specific cylinder amount of fuel to enter / inject into the relevant specific cylinder 1.

[0209] The cylinder controller is configured to adjust the common compression pressure signal according to the deviation between the common compression pressure signal and the actual specific cylinder compression pressure signal to obtain the specific cylinder compression pressure signal. Therefore, the cylinder controller continuously (or intermittently) calculates the error value according to the difference between the specific cylinder compression signal and the actual specific cylinder compression pressure, and applies correction based on the proportional term and the integral term (PI regulator) to obtain the specific cylinder compression pressure signal, and form a closed-loop control for the relevant specific cylinder 1.

[0210] In the same way, as described above with respect to the torque signal and the 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. Thus, erroneous signals are avoided from destabilizing the system, and larger corrections are allowed if all cylinders 1 have the same deployment.

[0211] The compression pressure module converts the compression pressure signal of the specific cylinder into an exhaust valve closing timing signal of the specific cylinder. At this point, the compression pressure module applies the compression pressure signal of the specific cylinder to a sixth predetermined map. The sixth predetermined map may include an algorithm and / or a lookup table that associates the compression pressure with the closing timing of the exhaust valve 4. The algorithm and / or the lookup table of the sixth predetermined map may be established through testing.

[0212] The exhaust valve closing timing signal of a specific cylinder is sent to the fuel valve 50 of the relevant cylinder 1, and instructs the exhaust valve actuator 46 when the exhaust valve 4 should be closed, that is, the time (angle) to close the exhaust valve 4. In response to the exhaust valve closing timing signal of the cylinder controller associated with the relevant cylinder 1, the exhaust valve actuator 46 of the relevant cylinder 1 is closed.

[0213] In an embodiment, the torque signal (mean indicated pressure) adjustment for a specific cylinder, the peak pressure adjustment for a specific cylinder, and the combustion pressure adjustment for a specific cylinder are sent back to the controller 55, and the average "mean indicated pressure adjustment", the average peak pressure adjustment, and the average combustion pressure adjustment are calculated. The 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, the average value of the combustion process parameters for all cylinders is calculated at the same cycle frequency as the adjustment cycle. The controller 55 sets limits for the adjustment of the specific cylinder of the corresponding combustion process parameter relative to the average value of the calculated relevant combustion process parameter. The limit can be in the form of a maximum predetermined deviation plus or minus the calculated average value. The predetermined positive deviation can be different from the predetermined negative deviation. Therefore, an interval is formed around the average value of the calculated relevant process parameters. The predetermined positive and negative deviations are process parameter specific. The integrator saturation will be variable, so that a larger adjustment is allowed when the average adjustment of torque, peak pressure, and combustion pressure is larger.

[0214] The cylinder controller is configured to control the cylinder 1 of the engine individually without considering maintaining cylinder balance, that is, without cylinder balance. Therefore, each cylinder 1 is operated according to the design specifications by providing a specific cylinder feedback loop control for the average indicated pressure (torque) of the specific cylinder, and / or providing a specific cylinder feedback loop control for the peak pressure of the specific cylinder, and / or providing a specific cylinder feedback loop control for the compression pressure of the specific cylinder. Since all cylinders 1 will operate according to the design specifications, there is no need for cylinder balancing. This is particularly advantageous for dual-fuel engines after changing the fuel from one fuel to another. In conventional engines, this fuel change requires manual recalibration to enable the engine to operate optimally after the fuel change. Using the controller according to this document, there is no need for manual recalibration after changing the fuel. Peak pressure and torque are particularly important during the transition from fuel oil to S secondary fuel (such as gas), and this will be automatically ensured / regulated by this controller.

[0215] However, in some cases it may be necessary to operate one or more cylinders to different design specifications. For example, when cylinder 1 is in a state where it is determined that there is a significant risk of cylinder liner wear (sticking), which is sometimes caused by insufficient cylinder lubrication. It may be necessary to reduce the load on a cylinder that gives a signal that wear is occurring or will occur soon if the load is not reduced.

[0216] Therefore, in Figure 5In the embodiment of the controller shown in the embodiment, each cylinder controller includes a cylinder-specific cylinder compensation module for each cylinder 1. In this embodiment, for simplicity, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are represented by the same reference numerals as used previously. This embodiment of the controller 55 is similar to the embodiment of the controller 55 except that the cylinder-specific compensation module is added. Figure 4 The implementation methods are basically the same.

[0217] The cylinder-specific compensation module is configured to compensate for a common torque signal, a common peak pressure signal and / or a common compression pressure signal relative to the associated specific cylinder 1. For example, compensation can be introduced automatically or by a manual operator based on a signal from a sensor that causes a cylinder controller or controller to introduce a compensation setting for a specific cylinder 1. For example, the detection of knock in a specific cylinder can be detected by a sensor. In response to such a knock sensor, the compression pressure of the specific cylinder is reduced by the controller 55 to reduce the temperature in the combustion chamber, thereby reducing the risk of knock. Therefore, cylinder-specific compensation will be introduced for the associated cylinder. In addition, in an embodiment, the controller 55 is configured to increase the air-fuel ratio by compensating for the cylinder-specific compensation for the amount of fuel to be injected and by reducing the amount of fuel.

[0218] Therefore, the cylinder compensation module outputs a cylinder-specific torque set point, a cylinder-specific peak pressure set point, and a cylinder-specific compression pressure set point. Figure 4 In the same manner as the implementation method of the embodiment, the set point of the specific cylinder is adjusted according to the difference between the corresponding actual specific cylinder torque, the specific cylinder peak pressure and the specific cylinder compression pressure, thereby respectively obtaining the specific cylinder torque, the specific cylinder peak pressure and the specific cylinder compression pressure.

[0219] Figure 6 Another embodiment of the controller 55 is shown. In this embodiment, for simplicity, structure and features that are the same or similar to corresponding structure and features previously described or shown herein are represented by the same reference numerals used previously. This embodiment of the controller 55 is similar to the above except that a fuel indicator is added to the profile duration module. Figure 5 The implementation of the invention is substantially the same. The fuel indicator of the profile duration module is configured to convert the fuel indicator signal into a common profile duration signal.

[0220] Each cylinder controller receives the common profile duration signal and adjusts the common fuel delivery duration signal according to a deviation between the common fuel delivery duration signal and the torque signal of the specific cylinder to obtain a fuel profile duration signal of the specific cylinder.

[0221] The addition of a common profile duration signal makes the engine more robust to fluctuations in fuel quality. In particular the properties of gaseous fuels tend to vary, for example the gas LCV (lower heating value) can vary by up to 30% to 50%.

[0222] In an embodiment, the common torque signal corresponds to an average indicated cylinder pressure of all cylinders and wherein the cylinder-specific torque signal corresponds to an average indicated cylinder pressure of the associated specific cylinder.

[0223] Various aspects and embodiments have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments may be understood and implemented by those skilled in the art who practice the claimed subject matter by studying the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor, controller or other unit may perform the functions of several items recited in a claim. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0224] Reference signs used in the claims should not be construed as limiting the scope. Unless otherwise noted, the drawings (e.g., hatching, arrangement of components, proportions, extent, etc.) are intended to be read together with the specification and should be considered part of the entire written description of the present disclosure.

Claims

1. A large, low-speed, two-stroke, single-flow scavenging turbocharged internal combustion engine having a crosshead (9), the engine comprising: A plurality of cylinders (1), each 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 quantity of a first fuel to the associated cylinder (1), a pressure sensor (42) for generating a cylinder-specific pressure signal, the cylinder-specific pressure signal being representative of the pressure in the associated cylinder (1), an exhaust-driven turbocharger (5) which pressurizes scavenging air for the cylinder (1), A controller (55) receives the following actual operating state of the engine, or the controller (55) is configured to determine the following actual operating state of the engine: a common torque signal representative of the torque to be delivered by said engine, a common peak pressure signal representative of the peak cylinder pressure to be achieved in said cylinder (1), a common compression pressure signal indicative of the compression pressure to be achieved in the cylinder (1), the controller (55) receiving the pressure signal of the specific cylinder, in: a) the controller (55) is configured to: derive from the cylinder-specific pressure signal an actual cylinder-specific torque signal representing the torque delivered by the associated cylinder-specific pressure signal; and adjusting the common torque signal according to a deviation between the common torque signal and the actual torque signal of the specific cylinder to obtain a torque signal of the specific cylinder; and delivering a certain amount of fuel to the specific cylinder according to the torque signal of the specific cylinder, as well as b) the controller (55) is configured to: derive an actual specific cylinder peak pressure signal representing the peak pressure in the associated cylinder (1) from the pressure signal of the specific cylinder; adjust the common peak pressure signal according to a deviation between the common peak pressure signal and the actual specific cylinder peak pressure signal to obtain a specific cylinder peak pressure signal; and determine a time to start delivering the certain amount of fuel to the associated specific cylinder according to the peak pressure signal of the specific cylinder, as well as c) The controller (55) is configured to: derive an actual compression pressure signal of the specific cylinder representing the compression pressure in the associated cylinder (1) from the pressure signal of the specific 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 determine the time to close the exhaust valve of the associated specific cylinder according to the compression pressure signal of the specific cylinder.

2. The engine according to claim 1, wherein: The engine is either fuel driven or air driven.

3. The engine according to claim 1, wherein: The engine is partly fuel driven and partly air driven.

4. The engine according to any one of claims 1 to 3, wherein: The engine is a dual fuel engine and wherein the fuel delivery system (30) is configured to handle at least two different fuels and the cylinders (1) are each provided with at least one fuel valve (50) for delivering a first fuel and at least one fuel valve (50) for delivering a second fuel.

5. The engine according to claim 4, wherein: The engine is fuel-driven when operating on the first fuel and is air-driven when operating on the second fuel.

6. The engine according to any one of claims 1 to 3, wherein: The controller (55) receives a desired engine speed and receives a measured engine speed, and wherein the controller (55) includes a regulator configured to determine a fuel indicator signal based on a deviation of the desired engine speed from the measured engine speed.

7. The engine according to claim 6, wherein: The controller (55) is configured to convert the fuel indicator signal into the common torque signal by applying the fuel indicator signal to a first predetermined map.

8. The engine according to claim 7, wherein: The controller (55) includes a power calculation module configured to calculate an engine load signal indicative of engine load, the power calculation module receiving the fuel indicator signal and the measured engine speed.

9. The engine according to claim 8, wherein: The controller (55) is configured to: - determining said common peak pressure signal by applying said engine load signal to a second predetermined map, and / or - determining said common compression pressure by applying said engine load signal to a third predetermined map.

10. The engine according to any one of claims 1 to 3, wherein: The controller (55) includes a fuel indicator signal to profile duration module configured to convert the fuel indicator signal to a common fuel delivery duration signal.

11. The engine according to claim 10, wherein: The controller (55) is configured to adjust the common fuel delivery duration signal according to a deviation of the common fuel delivery duration signal from the torque signal of the specific cylinder to obtain a fuel delivery duration signal of the specific cylinder.

12. The engine according to claim 11, wherein: The controller (55) is configured to determine an injection profile of a specific cylinder based on a torque signal of the specific cylinder or based on a fuel delivery duration signal of the specific cylinder, and wherein the fuel delivery system (30) delivers the amount of fuel to the associated specific cylinder by opening one or more fuel valves (50) based on the injection profile of the specific cylinder.

13. An engine according to any one of claims 1 to 3, wherein: The fuel delivery system (30) starts delivering the quantity of fuel to the associated specific cylinder by opening one or more fuel valves (50) according to the start timing of delivery of the quantity of fuel determined by the controller (55).

14. An engine according to any one of claims 1 to 3, wherein: The controller (55) is configured to: - limiting the amplitude of the adjustment of the common torque signal to a first threshold value when the adjustment for the other cylinders (1) is in the same direction, and wherein the controller (55) is configured to limit the amplitude of the adjustment of the common torque signal to a second threshold value when the adjustment for the other cylinders (1) is in the opposite direction, and / or limiting the amplitude of the adjustment of the common peak pressure signal to a first threshold value when the adjustment for the other cylinders (1) is in the same direction, and wherein, in the case where the engine has element b), the controller (55) is configured to limit the amplitude of the adjustment of the common peak pressure signal to a second threshold value when the adjustment for the other cylinders (1) is in the opposite direction, and / or The amplitude of the adjustment of the common compression pressure signal is limited to a first threshold value when the adjustment for the other cylinders (1) is in the same direction, and wherein, in the case where the engine has element c), the controller (55) is configured to limit the amplitude of the adjustment of the common compression pressure signal to a second threshold value when the adjustment for the other cylinders (1) is in the opposite direction.

15. The engine according to claim 14, wherein: The second threshold is lower than the first threshold.

16. The engine according to claim 9, wherein: The first predetermined map, the second predetermined map and / or the third predetermined map are preset at an engine factory based on tests of the relevant engine or an identical or equivalent engine.

17. An engine according to any one of claims 1 to 3, wherein: The common torque signal corresponds to an average indicated cylinder pressure for all of the cylinders, and wherein the cylinder-specific torque signal corresponds to an average indicated cylinder pressure associated with the specific cylinder.

18. An engine according to any one of claims 1 to 3, wherein: The controller (55) includes a cylinder-specific cylinder compensation module for each cylinder, the cylinder-specific cylinder compensation module being configured to compensate the common torque signal, the common peak pressure signal, and / or the common compression pressure signal relative to the associated specific cylinder.

19. The engine of claim 18, wherein: The cylinder compensation module for the specific cylinder is manually controlled or automatically controlled.

20. An engine according to any one of claims 1 to 3, wherein: The controller (55) is configured to control the cylinders (1) of the engine individually without considering cylinder balance.

21. An engine according to any one of claims 1 to 3, wherein: The controller (55) is configured to continuously calculate an error value based on the difference between the cylinder-specific torque and the actual cylinder-specific torque and to apply a correction based on a proportional term and an integral term if the engine has element a), The controller (55) is configured to continuously calculate an error value based on the difference between the peak pressure of the specific cylinder and the actual peak pressure of the specific cylinder, and to apply correction based on proportional terms and integral terms when the engine has element b). The controller (55) is configured to continuously calculate an error value based on the difference between the compression pressure of the specific cylinder and the actual compression pressure of the specific cylinder, and to apply correction based on proportional terms and integral terms when the engine has element c).

22. An engine according to any one of claims 1 to 3, wherein: The fuel delivery system (30) is also configured to deliver a quantity of a second fuel to the associated cylinder (1).

23. A large, low-speed, two-stroke, single-flow scavenged, turbocharged internal combustion engine having a crosshead (9), the engine comprising: - A plurality of cylinders (1), each cylinder (1) having: Exhaust valve (4), an exhaust valve actuation system (46) for actuating the exhaust valve (4), and a fuel delivery system (30) for delivering a quantity of a first fuel to the associated cylinder (1), - an exhaust-gas-driven turbocharger (5) which pressurizes scavenging air for the cylinder (1), a controller (55) configured to control at least one of one or more combustion process parameters, fuel quantity, timing of start of fuel injection and timing of exhaust valve closing in a cylinder-specific manner, The controller (55) is configured to: The engine is characterized in that the controller is configured to: calculating an average of cylinder-specific adjustments of the one or more combustion process parameters for the cylinder, and Adjustments of the particular cylinder in a cycle of the one or more combustion process parameters are limited to a calculated average of the adjustments of the relevant combustion process parameters plus or minus a maximum predetermined deviation.

24. The engine of claim 23, wherein: The controller (55) is configured to define an interval as an average of the calculated adjustments of the relevant combustion process parameters plus or minus a maximum predetermined deviation, and to limit adjustments of the particular cylinder in a cycle of the one or more combustion process parameters to adjustments within the interval.

25. The engine of claim 24, wherein: The interval is a range having a first range in a positive direction and a second range in a negative direction relative to the calculated adjusted mean value of the relevant combustion process parameter.

26. The engine of claim 25, wherein: The intervals are specific to the combustion process parameters.

27. The engine of claim 26, wherein: The first range has a first predetermined magnitude, and wherein the second range has a second predetermined magnitude.

28. An engine according to any one of claims 23 to 27, wherein The controller (55) is configured to calculate an average value of cylinder-specific adjustments to one or more combustion process parameters for the cylinders for one or more cycles of cyclic adjustments of the associated combustion process parameters.

29. An engine according to any one of claims 23 to 27, wherein The adjustment of the one or more combustion process parameters is an adjustment for a single cycle.

30. An engine according to any one of claims 23 to 27, wherein The at least one combustion process parameter includes: - amount of fuel, - the timing of the start of fuel injection, and / or -Timing of exhaust valve closing.

31. An engine according to any one of claims 23 to 27, wherein: The cylinder-specific setpoint for the one or more combustion process parameters is an offset to a common setpoint for the one or more combustion process parameters.

32. An engine according to any one of claims 23 to 27, wherein: The operating conditions of the engine are one or more of: engine speed, engine load, cylinder peak pressure, cylinder combustion pressure, cylinder indicated mean pressure, scavenging pressure, fuel type, ambient humidity, and ambient temperature.

33. A method of operating a large, low speed, two-stroke, uniflow scavenged, turbocharged internal combustion engine having a crosshead (9), the engine comprising: - A plurality of cylinders (1), each cylinder (1) having: Exhaust valve (4), an exhaust valve actuation system (46), the exhaust valve actuation system (46) being used to actuate the exhaust valve (4), a fuel delivery system (30) for delivering a quantity of a first fuel to the associated cylinder (1), - an exhaust-gas-driven turbocharger (5) which pressurizes scavenging air for the cylinder (1), The method comprises: controlling at least one of one or more combustion process parameters, fuel quantity, timing of start of fuel injection and timing of exhaust valve closing in a cylinder-specific manner, The method is characterized in that the one or more combustion process parameters of the cylinder (1) are individually controlled according to the operating state of the engine by cyclically adjusting a common set point or a cylinder-specific set point for the one or more combustion process parameters in a cylinder-specific manner, calculating a mean value for said cylinder-specific adjustments of said one or more combustion process parameters, determining an interval around the calculated average value adjusted for the one or more combustion process parameters, and Adjustments of the particular cylinder in a cycle of the one or more combustion process parameters are limited to a calculated average of the adjustments of the associated combustion process parameters plus or minus a maximum predetermined deviation.

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