Internal combustion engine

Abstract

To provide an internal combustion engine and a method of operating the internal combustion engine that reduce or prevent an imbalance of recirculated exhaust gas.SOLUTION: An internal combustion engine 10 comprises at least one cylinder 11 having an inner diameter 12 of at least 200 mm. The internal combustion engine 10 comprises a system 40 for exhaust gas recirculation with at least two EGR paths 41a, 41b fluidly arranged at least partly in parallel between an exhaust outlet 13 and an air inlet 14 of the cylinder. Each EGR path comprises at least one EGR valve 42a, 42b and / or at least one EGR blower 49, 49a, 49b. Each EGR path is fluidly connected or connectable to a respective sensing path 51a, 51b, which is fluidly connected or connectable to a measuring path 53 with at least one gas sensor device 54 providing values representative of the amount of EGR gas in the respective EGR path.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an internal combustion engine having a system for exhaust gas recirculation, and a method for operating the internal combustion engine.

[0002] The present invention preferably relates to an internal combustion engine such as a large marine engine, a ship engine, or a stationary engine, the cylinder of which has an inner diameter of at least 200 mm. The engine is preferably a two-stroke engine or a two-stroke cross-head engine. The engine can be a diesel engine, a gas engine, a dual-fuel or multi-fuel engine. In such an engine, combustion of liquid fuel and gas fuel is possible, in addition to self-ignition or forced ignition.

Background Art

[0003] The engine has at least one cylinder having a piston inside. The piston is connected to a crankshaft. During operation of the engine, the piston reciprocates between the top dead center (TDC) and the bottom dead center (BDC). The cylinder generally has at least one ventilation opening for intake, particularly an air inlet disposed in the liner of the cylinder, and at least one ventilation opening for exhaust, particularly an exhaust outlet disposed in the cover of the cylinder.

[0004] The internal combustion engine can be a two-stroke engine flushed in the vertical direction.

[0005] The term internal combustion engine also refers to large engines that can operate not only in the diesel mode characterized by self-ignition of fuel, but also in the Otto mode characterized by positive ignition of fuel, or in a mixture of the two. Furthermore, the term internal combustion engine particularly includes dual-fuel engines and large engines in which self-ignition of fuel is used for positive ignition of another fuel.

[0006] The engine speed is preferably less than 800 RPM (4-stroke), which indicates a low-speed engine, and more preferably less than 200 RPM (2-stroke).

[0007] The fuel may be diesel oil, or marine diesel oil, or heavy oil, or emulsion, or slurry, or methanol, or ethanol, or gases such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG).

[0008] Further potential fuels that can be added upon request include LBG (liquefied biogas), biofuels (such as algal fuels and seaweed oil), hydrogen, and synthetic fuels from CO2 (e.g., formed by Power-To-Gas or Power-To-Liquid).

[0009] To reduce the reactivity of the gas / air mixture and methane slip, exhaust gas recirculation (EGR), particularly low-pressure exhaust gas recirculation (EGR) as described in, for example, European Patent Application Publication No. 3722572(A1), is known. A portion of the exhaust gas is recirculated to the cylinder, while the other portion is guided to a funnel and released into the environment.

[0010] For example, according to German Patent No. 4222414(C2) and European Patent Application Publication No. 0896139(A2), an oxygen sensor is provided at least in the intake manifold and connected to a control unit, which determines the actual exhaust gas recirculation rate from the signal generated by the oxygen sensor. The exhaust gas recirculation valve is controlled accordingly.

[0011] U.S. Patent No. 7,783,408 (B2) discloses an engine with multiple cylinders. Each cylinder is supplied with exhaust gas introduced through a common EGR valve. A control unit detects an air-fuel ratio imbalance between cylinders based on the cylinder-specific air-fuel ratio detected by an air-fuel ratio sensor located in the cylinder's exhaust pipe. If there is an air-fuel ratio imbalance between cylinders, the EGR valve is closed. The EGR rate for individual cylinders is not given.

[0012] U.S. Patent No. 6,382,198 (B1) discloses an internal combustion engine fuel control system in which a single oxygen sensor responds to the combined exhaust gas flow of several engine cylinders. The oxygen sensor output is sampled in synchronization with engine ignition events and serves as an indicator of air-fuel ratio imbalance over time. Because sampling must be synchronized with engine ignition events, a considerable computational load is placed on the engine controller. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] European Patent Application Publication No. 3722572(A1) [Patent Document 2] German Patent No. 4222414 (C2) [Patent Document 3] European Patent Application Publication No. 0896139(A2) [Patent Document 4] US Patent No. 7783408(B2) [Patent Document 5] U.S. Patent No. 6,382,198 (B1) [Overview of the project] [Problems that the invention aims to solve]

[0014] The object of the present invention is to avoid the drawbacks of the prior art, and in particular to provide an internal combustion engine and a method for operating an internal combustion engine that reduce or prevent imbalances in recirculated exhaust gases. [Means for solving the problem]

[0015] According to the present invention, the internal combustion engine is a large engine, such as a marine engine or a stationary engine. The internal combustion engine is preferably a two-stroke engine or a two-stroke cross-head engine. The internal combustion engine has at least one cylinder having a bore of at least 200 mm.

[0016] Generally, a cylinder has at least one air inlet and at least one exhaust outlet. Preferably, the internal combustion engine is a vertically-flushed reciprocating piston combustion engine with a scavenging port at the lower part of the cylinder wall and an exhaust outlet at the cylinder cover.

[0017] The internal combustion engine can have a plurality of cylinders supplied from a common scavenging receiver and discharging exhaust gas into a common exhaust manifold.

[0018] Preferably, the internal combustion engine has at least one turbocharger with a turbine and a compressor.

[0019] [[ID=q12]] The internal combustion engine has a system for exhaust gas recirculation with at least two EGR paths fluidly arranged at least partially in parallel between the exhaust outlet and the air inlet of the cylinder.

[0020] A common EGR pipe may be divided into parallel lines, and the exhaust gas in each line is mixed with fresh air.

[0021] For example, when there are a plurality of scavenging lines supplying fresh air or a mixture of fresh air and exhaust gas to the scavenging receiver or the air inlet of the cylinder, and / or when there is an enlarged scavenging receiver, a plurality of EGR paths may be required. A plurality of scavenging lines and / or an enlarged scavenging receiver may generally be required for an internal combustion engine with a plurality of cylinders that also have a plurality of turbochargers.

[0022] The scavenging line guiding the mixture of fresh air and exhaust gas may be understood as part of an EGR path downstream of the mixing zone where fresh air and exhaust gas are mixed.

[0023] Each EGR path has at least one EGR valve and / or at least one EGR blower. Preferably, each EGR path also has an EGR cooler, an EGR demister, an EGR scrubber, and / or an EGR economizer.

[0024] Preferably, each EGR path is fluidly connected to or connectable to each sensing path.

[0025] Alternatively, only at least two selected EGR paths out of the plurality of EGR paths are fluidly connected to or connectable to each sensing path.

[0026] Being fluidly connected generally means that a fluid, which is generally EGR gas or a mixture of EGR gas and fresh air, can be guided from the EGR path to the sensing path. The fluid connection can be prevented, for example, by a closed valve between the EGR path and the sensing path or a closed valve within the sensing path.

[0027] The sensing path is fluidly connected to or connectable to a measurement path. The measurement path has at least one gas sensor device that provides a value representing the amount of EGR gas within each EGR path.

[0028] The sensing path may be established by a sensing path pipe that is connected to each EGR path, for example, a pipe of each EGR path, or an inlet air cooler arranged in each EGR path.

[0029] Since only a small amount of gas is required for measurement, the sensing path may have a pipe diameter smaller than the pipe diameter of the EGR path pipe. For example, the sensing path may have a pipe diameter of 8 - 25 mm, while the pipe diameter of the EGR path pipe is 360 - 800 mm.

[0030] The sensing path conducts only a very small part of the total mass flow rate of the EGR path.

[0031] The sensing path can have at least one sensing valve for establishing fluid connection to the EGR path and / or the measurement path.

[0032] The gas sensor device can provide a value representing the concentration of EGR gas in each EGR path, preferably in the portion of the EGR path that includes fresh air and exhaust gas, when exhaust gas recirculation is in operation. The value representing the concentration of EGR gas is considered to be a value representing the amount of EGR gas.

[0033] Gas sensor devices include O2 sensors and NO sensors. x The system may have at least one gas sensor for evaluating the type of EGR amount or EGR concentration, such as a sensor and / or a CO2 sensor.

[0034] Each sensing path can branch off from its respective EGR path downstream of the mixing zone where fresh air and exhaust gases mix. In the low-pressure EGR path, the sensing path can branch off downstream of the turbocharger compressor, as will be further explained below.

[0035] On the one hand, the measurement path may be connectable to the EGR path, and on the other hand, the measurement path may be connected directly to any suitable path for guiding the exhaust gas, or to the funnel. Preferably, in the suitable path for guiding the exhaust gas, the pressure is lower than in the portion of the EGR path where the sensing path branches off.

[0036] The internal combustion engine may have a first control unit, which is configured to receive a value provided by at least one gas sensor device and to operate an EGR valve and / or EGR blower after mixing with fresh air to provide essentially the same EGR concentration to all EGR paths.

[0037] Equal EGR concentration in the downstream EGR path of the mixing zone results in a balanced EGR concentration at all air inlets and / or a uniform EGR concentration at the scavenging receiver, and therefore can also result in an equal EGR concentration at all cylinders.

[0038] The first control unit balances the EGR concentration for all air inlets or scavenging lines. The EGR concentrations in different EGR paths downstream of the mixing zone where exhaust gas is mixed with fresh air must not deviate by more than ±1% from the mean of each other and / or all EGR paths.

[0039] The overall EGR rate is generally not affected by the operation of the first control unit.

[0040] However, the first control unit may also be part of an engine control unit that controls the overall EGR rate according to ambient conditions, load, cylinder temperature and / or cylinder pressure, preferably determined by a closed-loop controller in gas mode or diesel mode.

[0041] Preferably, the first control unit operates at least one flow control valve in each of the at least one EGR paths. The setting of the flow control valve can be varied in steps of 0.5% to 1% or 0.45° to 0.9° for a butterfly valve. 100% opening may correspond to a valve setting of 90°.

[0042] Generally, the flow control valves of two or more of the multiple EGR pathways must be operated to balance the concentration without changing the overall EGR rate.

[0043] If the value determined by the sensor in each EGR path is less or more than the average value of all EGR paths by a predetermined value or percentage, the EGR valve in that EGR path can be further opened or closed.

[0044] In addition to or instead of this, if the value determined by the sensor is less or more than the average value of all EGR paths by a predetermined value or percentage, the EGR blower of the EGR path can be accelerated or decelerated.

[0045] A predetermined value or percentage can be stored in the control unit. This predetermined value or percentage can be determined based on shop tests.

[0046] The first control unit may activate the EGR valve and / or EGR blower as soon as the internal combustion engine reaches a stable operating point. For example, the stable operating point is reached when the load, ambient conditions, and / or cylinder pressure conditions no longer change and an overall EGR rate is selected.

[0047] For example, if the load is constant and the respective closed-loop controllers in gas mode or diesel mode do not change the settings of the back pressure valve and flow control valve, the settings remain constant during measurement. In this case, it can be assumed that the EGR rate is approximately constant during measurement.

[0048] The measurement time is preferably within a few minutes.

[0049] As soon as the internal combustion engine reaches its stable operating point, measurements of the amount of EGR gas in the EGR path can be taken continuously or periodically at specific time intervals, for example, every few minutes.

[0050] Preferably, two or more EGR paths can be connected to a common measurement path.

[0051] More preferably, the internal combustion engine has only one measurement path, and all EGR paths are connectable to the measurement path. Each sensing path branching off from each EGR path may be fluid-connected to or connectable to the measurement path.

[0052] Since the values ​​representing the amount of EGR in the EGR path are given by the same gas sensor device, and only the difference between the respective measurements is important, calibration of the gas sensor system for absolute values ​​is not necessary.

[0053] Each sensing path may have a sensing valve to establish and prevent fluid connections between its respective EGR path and measurement path.

[0054] The sensing valve can be switched quickly and reliably to prevent cross-contamination of various EGR pathways. Preferably, a magnetic valve is used as the sensing valve.

[0055] The internal combustion engine may have a second control unit configured to operate a sensing valve to connect the measurement path to each EGR path in a continuous manner.

[0056] The second control unit may be part of the first control unit and / or part of the engine control unit.

[0057] A second control unit may be configured to perform a measurement cycle. The measurement cycle may have at least the following steps:

[0058] First, all sensing valves are opened to heat the gas sensor device, especially the gas sensor itself.

[0059] All sensor valves can be closed, and the first sensor valve can be opened.

[0060] Alternatively, all sensing valves except the first sensing valve may be closed, the first EGR path may be connected to the measurement path, and all other sensing valves may be closed.

[0061] Alternatively, the first sensing valve may be opened without opening all the sensing valves beforehand.

[0062] When the first sensing valve opens, a value representing the amount of EGR gas in the first EGR path can be determined.

[0063] Preferably, the first sensing valve is open for a first time interval, for example 30 seconds, to flush the measurement path with the exhaust gas of the first EGR path, and the first sensing valve remains open for the immediately following second time interval, for example 60 seconds, in which case the gas sensor device collects data and provides a value representing the amount and / or concentration of EGR gas in the first EGR path.

[0064] During the second time interval, the average values ​​for the amount and / or concentration of EGR gas in the first EGR pathway can be determined. The first sensing valve is then closed.

[0065] The second sensing valve is opened after or before the first sensing valve is closed in order to connect the second EGR path to the measurement path while all other sensing valves remain closed.

[0066] The second sensing valve may be open for a time interval as described for the first sensing valve. The second time interval may begin after the first sensing valve has been closed.

[0067] When the second sensing valve opens, a value representing the amount of EGR gas in the second EGR path can be determined.

[0068] The average value of the amount and / or concentration of EGR gas in the second EGR pathway can be determined. Then, the second sensing valve is closed.

[0069] Preferably, if available and / or selected, additional sensing valves are opened and closed in succession as described above for the second sensing valve. A value representing the amount of EGR gas in the additional EGR path can be determined.

[0070] To ensure the gas sensor remains at a high temperature, there may be overlapping opening times for continuously opened sensing valves.

[0071] Finally, the overall average of the values ​​determined for each EGR path can be determined.

[0072] The first control unit may be configured to determine the average value and the overall average value after receiving the values ​​provided by the gas sensor device.

[0073] If the value of each EGR path differs from the overall average value by a predetermined limit value or predetermined limit percentage, the first control unit can activate the respective EGR valve and / or EGR blower for each EGR path.

[0074] The second control unit may be configured to immediately execute at least two consecutive measurement cycles so that the average value representing the amount of EGR gas in each EGR path can be determined over two or more measurement cycles.

[0075] The second control unit may be configured to perform measurement cycles repeatedly or periodically after a predetermined time interval so that the amount of EGR gas in each EGR path or a value representing the average value of each can be continuously determined.

[0076] An internal combustion engine may have a low-pressure system for exhaust gas recirculation.

[0077] An internal combustion engine with a low-pressure system has a low-pressure EGR path. The internal combustion engine may have at least one turbocharger, which includes a turbine and a compressor.

[0078] In a low-pressure EGR system, exhaust gas can be guided through the turbocharger turbine, and at least a portion of the exhaust gas can be diverted downstream of the turbine and guided to the cylinder air inlet via the turbocharger compressor.

[0079] An internal combustion engine may have at least one turbocharger for each EGR path. In each low-pressure EGR path, exhaust gas may be guided through the respective compressors of the respective turbochargers.

[0080] An internal combustion engine with a low-pressure EGR system may have an inlet air cooler downstream of the compressor. The sensing path may branch upstream or downstream of the inlet air cooler.

[0081] If the sensing path branches upstream of the inlet air cooler, warmer gas will be guided to the gas sensor device. Otherwise, colder gas may have a higher moisture content, and the gas sensor device may need to be warmed to prevent condensation.

[0082] Alternatively, an internal combustion engine may have a high-pressure EGR system.

[0083] An internal combustion engine may have at least one turbocharger, which includes a turbine and a compressor. In a high-pressure system for exhaust gas recirculation, the exhaust gas can be diverted upstream of the turbine of the turbocharger, and at least a portion of the exhaust gas can be guided to the air inlet of the cylinder. The recirculated exhaust gas can be mixed with scavenging gas downstream of the compressor of the turbocharger.

[0084] An internal combustion engine may have two or more turbochargers. The exhaust gas from each upstream turbine can be branched for recirculation. Downstream of each compressor, the exhaust gas can be mixed with fresh air in its respective mixing zone.

[0085] According to the present invention, the method for starting the aforementioned internal combustion engine comprises the following steps.

[0086] The EGR pathway is continuously fluidly connected to a measurement pathway equipped with a gas sensor device. For each EGR pathway, the gas sensor device provides a value representing the amount of EGR gas in that pathway and / or the concentration of the exhaust gas downstream of each mixing zone.

[0087] The EGR valve and / or EGR blower are operated to balance the amount of EGR gas in the EGR path and / or the values ​​representing the concentration of exhaust gas downstream of each mixing zone.

[0088] It is not necessary to explicitly determine the amount and / or concentration of EGR gas in the EGR path and / or the concentration of exhaust gas downstream of each mixing zone. For example, it is sufficient to simply compare the measured values ​​with each other and / or with the overall average.

[0089] In particular, this method includes the following steps:

[0090] First, all sensing valves can be opened to heat the gas sensor device. Then, all sensing valves can be closed, and the first sensing valve can be opened.

[0091] Alternatively, all sensing valves except the first sensing valve may be closed.

[0092] Alternatively, the first sensing valve may be opened without opening all the sensing valves beforehand.

[0093] Therefore, while all other sensing valves are closed, the first EGR path is connected to the measurement path.

[0094] A value is given representing the amount of EGR gas in the first EGR path and / or the concentration of exhaust gas downstream of each mixing zone. The first sensing valve may remain open over the first and second time intervals. Preferably, a value is given only in the second time interval, and / or an average value over the second time interval is determined.

[0095] The first sensing valve is closed. The second sensing valve is opened either before or after the first sensing valve is closed in order to connect the second EGR path to the measurement path while all other sensing valves are closed.

[0096] A value is given representing the amount of EGR gas in the second EGR path and / or the concentration of the exhaust gas downstream of each mixing zone. The second sensing valve may remain open over the first and second time intervals, during which all other sensing valves, including the first sensing valve, are closed, a value is given, and / or the average value over the second time interval is determined. The first time interval may be 30 seconds, and the second time interval may be 60 seconds.

[0097] The second sensing valve is closed.

[0098] Preferably, if available and / or selected, additional sensing valves are successively opened and closed to provide values ​​representing the amount of EGR gas in further EGR paths and / or the concentration of exhaust gas downstream of each mixing zone.

[0099] All EGR paths, or only selected EGR paths, may be continuously connected to the measurement path.

[0100] Optionally, to improve measurement quality, several measurements are taken sequentially for each connected EGR path, and the average value for each EGR path or selected EGR path is determined.

[0101] The connection between each EGR path and the measurement path may remain established for at least several seconds. During this time, each sensing path may remain open.

[0102] The overall average value can be determined from the values ​​of all EGR paths. The difference between the overall average value and the values ​​of individual EGR paths can be determined, and the EGR valves and / or EGR blowers can be operated so that the difference is small enough that it does not deviate from the overall average value by more than ±1%.

[0103] The embodiments of the present invention will be further described below with reference to the figures. The same reference numerals refer to functionally corresponding features. [Brief explanation of the drawing]

[0104] [Figure 1] This is a schematic diagram of the first example of an internal combustion engine. [Figure 2] This is a schematic diagram of a second example of an internal combustion engine. [Figure 3] This is a schematic diagram of a third example of an internal combustion engine. [Figure 4] This is a schematic diagram of a fourth example of an internal combustion engine. [Figure 5] This is a schematic diagram of a fifth example of an internal combustion engine. [Figure 6] This is a schematic diagram of the sixth example of an internal combustion engine. [Figure 7] This is a schematic diagram of the seventh example of an internal combustion engine. [Figure 8] This is a schematic diagram of the eighth example of an internal combustion engine. [Figure 9] This is a schematic diagram of the ninth example of an internal combustion engine. [Modes for carrying out the invention]

[0105] Figure 1 shows a schematic diagram of a first example of an internal combustion engine 10. The internal combustion engine 10 has a cylinder 11 having a bore diameter 12 of at least 200 mm.

[0106] The internal combustion engine 10 has two turbochargers 30a, 30b, along with turbines 31a, 31b and compressors 32a, 32b.

[0107] The internal combustion engine 10 has a system 40 for exhaust gas recirculation, which includes two low-pressure EGR paths 41a and 41b fluidly arranged in parallel between the exhaust outlet 13 of the cylinder 10 and the air inlet 14 of the cylinder 10.

[0108] The exhaust gas can be guided through the turbines 31a and 31b of the turbochargers 30a and 30b. In each EGR path 41a and 41b, the recirculated exhaust gas can be guided to the air inlet 14 of the cylinder 11 through the compressors 32a and 32b of the turbochargers 30a and 30b, which form mixing zones 46a and 46b where the exhaust gas is mixed with fresh air.

[0109] Each EGR path 41a, 41b has an EGR valve 42a, 42b. All EGR paths 41a, 41b have a common shut-off valve 44. The pressure in the EGR paths 41a, 41b can be adjusted by a back pressure valve 43 located between the EGR paths 41a, 41b and the funnel 47.

[0110] Each of the EGR paths 41a and 41b is fluidly connected to the measurement path 53 via its respective sensing path 51a and 51b. Each sensing path 51a and 51b has sensing valves 52a and 52b for fluidly connecting the measurement path 53 to its respective EGR paths 41a and 41b. Each sensing path 51a and 51b branches off from its respective EGR paths 41a and 41b downstream of the mixing zones 46a and 46b, which are located downstream of the compressors 32a and 32b.

[0111] Each sensing path 51a, 51b is fluidly connected to a measurement path 53, which is accompanied by at least one gas sensor device 54. The gas sensor device 54 provides values ​​representing the amount of EGR gas in each EGR path 41a, 41b and / or the EGR concentration in each EGR path 41a, 41b downstream of the mixing zones 46a, 46b.

[0112] All EGR paths 41a and 41b can be connected to the same measurement path 53.

[0113] The internal combustion engine 10 has a first control unit 50 configured to receive values ​​provided by a gas sensor device 54. The first control unit 50 is configured to operate EGR valves 42a, 42b to provide essentially the same EGR concentration downstream of the mixing zones 46a, 46b to all EGR paths 41a, 41b.

[0114] The internal combustion engine 10 further includes a second control unit 60 configured to operate sensing valves 52a and 52b to connect a measurement path 53 to the respective EGR paths 41a and 41b.

[0115] The first control unit 50 and the second control unit 60 form an integrated control unit.

[0116] The measurement path 53 is fluidly connected to the second EGR path 41b upstream of the compressor 32b. Therefore, when connected to the respective EGR paths 41a and 41b, the measurement path 53 upstream of the gas sensor device 54 has the pressure level of the EGR path downstream of the compressors 32a and 32b, i.e., a higher pressure level, and the measurement path 53 downstream of the gas sensor device 54 has the pressure level of the EGR path upstream of the compressor 32b, i.e., a lower pressure level.

[0117] Figure 2 shows a schematic diagram of a second example of an internal combustion engine 10 similar to the first example. The EGR paths 41a and 41b are located between the exhaust manifold 15 and the scavenging receiver 25.

[0118] Before the recirculated exhaust gas is distributed to the first EGR path 41a and the second EGR path 41b, the exhaust gas is guided through the EGR cooler 45 and the EGR demister 48.

[0119] In this example, the measurement path is fluidly connected to the first EGR path 41a upstream of the compressor 32a.

[0120] The internal combustion engine 10 has inlet air coolers 33a and 33b downstream of each compressor 32a and 32b.

[0121] In principle, the sensing paths 51a and 51b can be branched from their respective EGR paths 41a and 41b upstream of the inlet air coolers 33a and 33b so that high-temperature air is guided to the gas sensor device 54.

[0122] Alternatively, the sensing paths 51a and 51b can branch off from their respective EGR paths 41a and 41b downstream of the inlet air coolers 33a and 33b, which are indicated by dashed lines (see also Figures 3 to 5).

[0123] Figure 3 shows a schematic diagram of a third example of an internal combustion engine 10, similar to the second example.

[0124] Figure 4 shows a schematic diagram of a fourth example of an internal combustion engine similar to the third example.

[0125] Instead of the back pressure valve 43 shown in Figures 1 to 3, an exhaust gas blower 49 is provided to establish sufficient pressure in the EGR paths 41a and 41b.

[0126] Figure 5 shows a schematic diagram of a fifth example of an internal combustion engine 10, similar to the fourth example.

[0127] Instead of the common EGR blower 40 shown in Figure 4, each EGR path 41a, 41b has its own EGR blower 49a, 49b.

[0128] In this case, the first control unit 50 is configured to operate the EGR valves 42a, 42b and / or EGR blowers 49a, 49b to supply essentially the same EGR concentration downstream of the mixing zones 46a, 46b to all EGR paths 41a, 41b.

[0129] Figure 6 shows a schematic diagram of a sixth example of the internal combustion engine 10.

[0130] The internal combustion engine 10 has two turbochargers 30a and 30b. The exhaust gas recirculation system 40 is a high-pressure system, and the exhaust gas can be diverted upstream of the turbines 31a and 31b of the turbochargers 30a and 30b.

[0131] A portion of the exhaust gas is guided to the scavenging receiver 25 via exhaust paths 41a and 41b, where it can be mixed with the scavenging gas in the respective mixing zones 46a and 46b located downstream of the compressors 32a and 32b of the turbochargers 30a and 30b.

[0132] Downstream of the mixing zones 46a and 46b, the respective sensing paths 51a and 51b branch off from the EGR paths 41a and 41b. Each sensing path 51a and 51b has sensing valves 52a and 52b for connecting the EGR paths 41a and 41b to the measurement path 53.

[0133] The measurement path 53 is fluid-connected to the funnel 47.

[0134] The integrated first and second control units 50 and 60 are -In order to continuously connect the EGR paths 41a and 41b to the measurement path 53, the sensing valves 52a and 52b are activated. - Receiving data representing the EGR concentration in the downstream EGR pathways 41a and 41b of the mixing zones 46a and 46b, -Operate the EGR valves 42a and 42b to balance the EGR concentrations in the downstream EGR paths 41a and 41b of the mixing zones 46a and 46b, and to bring a uniform EGR concentration into the scavenging receiver 25. It is configured in this way.

[0135] The first turbine 31a can be bypassed via a bypass 35 when the waste gate 34 is open. A back pressure valve 43 is located upstream of the bypass.

[0136] Figure 7 shows a schematic diagram of a seventh example of an internal combustion engine 10, similar to the sixth example. In this example, the bypass 35 branches upstream of the back pressure valve 43.

[0137] Figure 8 shows a schematic diagram of an eighth example of the internal combustion engine 10, similar to the sixth and seventh examples. Instead of a back pressure valve 43 (see Figures 6 and 7), an EGR blower 49 guides the exhaust gas to a first EGR path 41a and a second EGR path 41b. The first EGR path 41a and the second EGR path 41b have a common EGR cooler 45.

[0138] Figure 9 shows a schematic diagram of a ninth example of an internal combustion engine 10 similar to the eighth example. Instead of a common EGR blower 49 and a common EGR cooler 45 (see Figure 8), in this example each EGR path 41a, 41b has its own EGR blower 49a, 49b and its own EGR cooler 45a, 45b.

[0139] All figures show an example of an internal combustion engine 10 with two turbochargers and two parallel EGR paths 41a, 41b. However, the internal combustion engine 10 may have additional turbochargers and / or more parallel EGR paths (not shown).

[0140] Similarly, the internal combustion engine 10 may have two or more cylinders.

Claims

1. An internal combustion engine (10), that is, a large marine engine or a stationary engine, The internal combustion engine (10) has at least one cylinder (11) having an inner diameter (12) of at least 200 mm, The internal combustion engine (10) has an exhaust gas recirculation system (40) comprising at least two EGR paths (41a, 41b) fluidly arranged at least partially in parallel between the exhaust outlet (13) and the air inlet (14) of the cylinder (10), Each EGR path (41a, 41b) has at least one of at least one EGR valve (42a, 42b) and at least one EGR blower (49, 49a, 49b), An internal combustion engine (10) characterized in that each EGR path (41a, 41b) is fluidly connected to or connectable to its respective sensing path (51a, 51b), and the sensing paths (51a, 51b) are fluidly connected to or connectable to a measurement path (53) which has at least one gas sensor device (54) that provides a value representing the amount of EGR gas in each of the EGR paths (41a, 41b).

2. The internal combustion engine (10) according to claim 1, wherein each sensing path (51a, 51b) branches off from the respective EGR paths (41a, 41b) downstream of the mixing zone (46a, 46b) where fresh air and exhaust gas mix.

3. The internal combustion engine (10) according to claim 1, comprising a first control unit (50) configured to receive the values ​​provided by the at least one gas sensor device (54) and to operate at least one of the EGR valves (42a, 42b) and the EGR blowers (49a, 49b) to provide essentially the same EGR concentration to all EGR pathways (41a, 41b) after mixing with fresh air.

4. The internal combustion engine (10) according to claim 1, wherein the internal combustion engine has only one measurement path (53) and all EGR paths (41a, 41b) are connectable to the measurement path (53).

5. The internal combustion engine (10) according to claim 4, wherein each sensing path (51a, 51b) has a sensing valve (52a, 52b), and the internal combustion engine (10) has a second control unit (60) configured to operate the sensing valves (52a, 52b), thereby continuously connecting the measurement path (53) to the respective EGR paths (41a, 41b).

6. The second control unit (60) performs the following measurement cycle, i.e. The steps include opening all sensing valves (52a, 52b) to heat the gas sensor device (54), The steps include: closing all but one of the sensing valves (52a, 52b) so that the first EGR path (41a) is connected to the measurement path (53), enabling the determination of a value representing the amount of EGR gas in the first EGR path (41a) while all other sensing valves (52b) are closed, and closing the first sensing valve (51a); The steps are to open the second sensing valve (51b) to connect the second EGR path (41b) to the measurement path (53), at which point all other sensing valves (52a) are closed, enabling the determination of a value representing the amount of EGR gas in the second EGR path (41b), and then close the second sensing valve (51b). An internal combustion engine (10) according to claim 5, configured to perform a measurement cycle including the following:

7. The second control unit (60) is If available, the step involves continuously opening and closing additional sensing valves to enable the determination of values ​​regarding the amount of EGR gas in further EGR pathways. An internal combustion engine (10) according to claim 6, configured to perform a measurement cycle including the following:

8. The internal combustion engine (10) according to claim 6, wherein the second control unit (60) is configured to perform the measurement cycle at least twice, thereby determining a value relating to the average amount of EGR gas in each EGR path (41a, 41b).

9. The internal combustion engine has a low-pressure EGR path (41a, 41b), and the internal combustion engine (10) has at least one turbocharger (30a, 30b), and the turbocharger (30a, 30b) has a turbine (31a, 31b) and a compressor (32a, 32b), An internal combustion engine (10) according to claim 1, wherein exhaust gas can be guided through the turbines (31a, 31b) of the turbochargers (30a, 30b), and at least a portion of the exhaust gas can be guided through the compressors (32a, 32b) of the turbochargers (30a, 30b) to the air inlet (14) of the cylinder (11).

10. The internal combustion engine (10) according to claim 9, wherein the internal combustion engine has at least one turbocharger (30a, 30b) for each EGR path.

11. The internal combustion engine (10) according to claim 8, wherein the internal combustion engine has an inlet air cooler (33a, 33b) downstream of the compressor (32a, 32b), and the sensing path (51a, 51b) branches upstream or downstream of the inlet air cooler (33a, 33b).

12. The internal combustion engine (10) has at least one turbocharger (30a, 30b) having a turbine (31a, 31b) and a compressor (32a, 32b), The internal combustion engine (10) according to claim 1, wherein the exhaust gas recirculation system (40) is a high-pressure system, the exhaust gas can be branched upstream of the turbines (31a, 31b) of the turbochargers (30a, 30b), at least a portion of the exhaust gas can be guided to the air inlet (14) of the cylinder (11), and can be mixed with scavenging air downstream of the compressors (32a, 32b) of the turbochargers (30a, 30b).

13. The internal combustion engine (10) according to claim 1, wherein the internal combustion engine (10) is a two-stroke engine or a two-stroke cross-head engine.

14. A method for operating an internal combustion engine according to any one of claims 1 to 12, The steps include: connecting a plurality of EGR paths in a continuous manner to the measurement path; The steps include providing a value representing the amount of EGR gas in each of the aforementioned EGR pathways, The steps include operating at least one of the EGR valve and the EGR blower so that the values ​​representing the amounts of EGR gas in the multiple EGR paths are balanced, and Methods of including.

15. The steps include opening all sensing valves (52a, 52b) to heat the gas sensor device (54), A step of closing all sensing valves (52a, 52b) except for the first sensing valve (52a), thereby connecting the first EGR path (41a) to the measurement path (53) while all other sensing valves (52b) are closed. The steps include providing a value representing the amount of EGR gas in the first EGR path (41a) and closing the first sensing valve (51a), A step in which a second sensing valve (51b) is opened to connect a second EGR path (41b) to the measurement path (53), and all other sensing valves (52a) are closed at the same time, further a step in which a value representing the amount of EGR gas in the second EGR path (41b) is determined, and the second sensing valve (51b) is closed, and The method according to claim 14, including the method described in claim 14.

16. The method according to claim 15, further comprising the step of continuously opening and closing an additional sensing valve, if available, to determine a value relating to the amount of EGR gas in an additional EGR path.

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