Single-flow large turbocharged two-stroke internal combustion engine and method of operating the same

Abstract

The present disclosure provides a single-flow large turbocharged two-stroke internal combustion engine (100) and a method of operating such an engine (100) configured to supply pressurized scavenge and / or exhaust gas to a pressurized gas consumer (200). The engine includes a plurality of cylinders, an intake system, an exhaust system, one or more turbochargers having a turbine, a fuel system, a bypass system for supplying bypassed pressurized gas to the pressurized gas consumer by taking a controlled amount of scavenge from the intake system to bypass the engine and / or by taking a controlled amount of pressurized exhaust from the exhaust system to bypass the turbine, and a controller configured to adjust the amount of bypassed pressurized gas supplied to the consumer in accordance with sensed scavenge pressure and / or exhaust temperature. The controller is configured to operate the engine in a manner that makes various adjustments to maximize scavenge pressure and / or to maximize scavenge bypass mass flow.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method and a large turbocharged two-stroke internal combustion engine configured to produce pressurized gas for use in another application in addition to mechanical energy, e.g. for propulsion or driving a generator, and to a method of operating such an engine. BACKGROUND

[0002] Large turbocharged two-stroke self-igniting internal combustion engines are commonly used in propulsion systems for large vessels or as prime movers in power plants. The enormous size, weight and power output of these engines makes them completely different from ordinary combustion engines and sets the large two-stroke turbocharged compression ignition internal combustion engines apart. The height of these engines is not critical and therefore they are built with crossheads to avoid side loads on the pistons. Typically, these engines are operated on natural gas, oil gas, methane, ethane or fuel oil.

[0003] Large turbocharged two-stroke natural internal combustion engines for vessel propulsion (marine engines) are adapted to support certain fuel saving system arrangements on board the vessel. In particular, waste heat recovery systems are associated with reducing the overall energy consumption and reducing emissions from the marine engine.

[0004] In certain applications, the engine needs to provide pressurized gas, e.g. pressurized air, pressurized exhaust gas or a mixture of pressurized air and pressurized exhaust gas, in addition to providing mechanical energy, e.g. for propulsion. One such application is air lubrication. Ocean going vessels with a large flat bottom area can utilize the reduction of resistance when moving in water by air lubrication, thereby reducing the main engine power needed to propel the vessel at a given speed. The air lubrication system pumps a steady stream of air bubbles under the hull to lubricate the flat bottom area of the hull.

[0005] To achieve the desired reduction of the power needed for vessel propulsion, it is necessary to deliver a sufficient amount of air / gas to the dedicated bubble generator at a sufficient pressure depending on the draft of the vessel. Large two-stroke engines with standard adaptations are often limited to provide sufficient pressurized air / gas at all required engine loads.

[0006] JP2010228679A discloses a conventionally adapted engine with an output from the scavenge system for use by a consumer of pressurized gas. SUMMARY

[0007] It is an object of the present invention to provide a large turbocharged two-stroke internal combustion engine of uniflow type that overcomes or at least reduces the above-identified problems.

[0008] To avoid or at least reduce the installation and operation of expensive air compressor units, a suitable two-stroke engine is presented.

[0009] The foregoing and other objects are achieved by the aspects of the present disclosure. Further implementation forms are evident from the description and drawings.

[0010] According to a first aspect, there is provided a single-flow large turbocharged two-stroke combustion engine configured to supply a pressurized scavenge and / or exhaust gas to a pressurized gas consuming device, the engine comprising:

[0011] a plurality of cylinders having a scavenge port at a lower end portion of the cylinder and an exhaust valve at an upper end portion of the cylinder,

[0012] an intake system through which scavenge is introduced into the cylinder, the intake system comprising a scavenge receiver connected to the cylinder via the scavenge port,

[0013] an exhaust system through which exhaust gas produced in the cylinder is discharged, the exhaust system comprising an exhaust receiver connected to the cylinder via the exhaust valve,

[0014] at least one turbocharger having an exhaust driven turbine operably coupled to a compressor, an inlet of the turbine connected to the exhaust system, and an outlet of the compressor connected to the intake system for delivering a pressurized scavenge flow to the intake system,

[0015] a fuel system for delivering fuel to the cylinder,

[0016] a bypass system for supplying a bypassed pressurized gas to the pressurized gas consuming device by taking a controlled amount of scavenge from the intake system thereby bypassing the engine and / or by taking a controlled amount of pressurized exhaust gas from the exhaust system thereby bypassing the turbine, and

[0017] a controller coupled to the pressure sensor and / or the temperature sensor, the controller configured to adjust the amount of bypassed pressurized gas supplied to the consuming device in dependence of the sensed scavenge pressure and / or exhaust temperature,

[0018] wherein the controller is configured to operate the engine in one or more of the following ways to maximize the scavenge pressure and / or to maximize the scavenge bypass mass flow:

[0019] - increasing the power output of the turbocharger provided with a turbo hydraulic system arrangement,

[0020] - increasing the speed of an auxiliary blower in the intake system of the engine,

[0021] - increasing the speed of an EGR blower in an EGR device of the engine,

[0022] - starting an additional turbocharger device of the engine,

[0023] - opening a cylinder bypass valve in a cylinder bypass device of the engine,

[0024] - opening an exhaust bypass to a power turbine device of the engine for driving a dedicated electrically driven compressor,

[0025] - starting a hydraulically driven compressor powered by a hydraulic system device of the engine,

[0026] - adjusting the geometry of one or more variable geometry turbines of the turbochargers and thus the turbine flow area of the variable geometry turbines to maximize the pressure delivered by the compressors in actual operating conditions of the engine, preferably by reducing the turbine flow area to maximize the pressure delivered by the compressors in actual operating conditions of the engine,

[0027] - cutting off one or more of the turbochargers to maximize the pressure delivered by the compressors in partial load conditions of the engine, preferably cutting off one or more of the turbochargers as a function of the engine load to maximize the pressure delivered by the compressors in partial load conditions of the engine,

[0028] - starting one turbocharger below a first cut-off engine load threshold, two turbochargers in an interval between the first and a second cut-off engine load threshold, and three turbochargers above the second cut-off engine load threshold.

[0029] By providing a controller configured to apply various adjustment measures that increase the pressure available in the engine for supplying gas to the pressurized gas consumer, the amount of pressurized gas delivered by the engine for the pressurized gas consumer can be maximized without risking the engine to be operated in a suboptimal state. Considering that the bypass gas taken out of the engine cycle inherently leads to an increase of the engine fuel consumption, the engine according to the first aspect greatly enhances the commercial potential of ocean-going vessels with air lubrication. Moreover, by adjusting the engine with one or more of the listed measures to provide the highest possible scavenging pressure or the highest possible exhaust pressure, the engine can be turned into a pressurized gas supplier for delivering pressurized gas to an external pressurized gas consumer, such as an air lubrication system of an ocean-going vessel, which is much more efficient compared to using an air compressor driven by an electric motor, for example. Moreover, by adjusting the engine to provide the highest possible scavenging pressure or the highest possible exhaust pressure, the engine can be turned into a pressurized gas supplier for delivering pressurized gas to an external pressurized gas consumer, such as an air lubrication system of an ocean-going vessel, which is much more efficient compared to using an air compressor driven by an electric motor, for example.

[0030] In a first possible implementation form of the first aspect, the controller is configured to limit the amount of bypass pressurized gas supplied to the consumer when the sensed or observed scavenging pressure is below a scavenging pressure threshold and / or the sensed or observed exhaust gas temperature is above an exhaust gas temperature threshold.

[0031] In a further possible implementation form of the first aspect, the controller is configured to determine an actual engine turbocharging effect from the sensed or observed scavenging pressure and / or the sensed or observed exhaust gas temperature. The term "engine turbocharging effect" refers to the turbocharging effect experienced or felt by the engine, independent of ambient conditions.

[0032] In a further possible implementation form of the first aspect, the controller is configured to limit the amount of bypass pressurized gas supplied to the consumer in dependence on the determined actual engine turbocharging effect.

[0033] In a further possible implementation form of the first aspect, the controller is configured to determine an excess of the actual available effect of the one or more turbochargers compared to a predetermined minimum engine turbocharging effect threshold.

[0034] In a further possible implementation form of the first aspect, the controller is configured to limit the amount of bypass pressurized gas supplied to the consumer in dependence on the determined excess of the available effect of the one or more turbochargers.

[0035] In a further possible implementation form of the first aspect, the control unit is configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consuming device in dependence of a demand of the pressurized gas consuming device for pressurized gas, preferably in response to a signal from the pressurized gas consuming device, preferably while avoiding exceeding a threshold value.

[0036] In a further possible implementation form of the first aspect, the one or more turbochargers have a turbocharger effect exceeding a predetermined minimum required engine turbocharging effect at least in a given engine load range.

[0037] In a further possible implementation form of the first aspect, the one or more turbochargers have a turbo with a variable geometry turbine allowing to adjust the turbo flow area, the control unit is coupled to the one or more turbochargers for controlling the variable geometry of the turbine, and the control unit is configured to adjust the geometry of the turbine to maximize the pressure delivered by the compressor in the actual operating state of the engine, preferably by reducing the turbo flow area.

[0038] In a further possible implementation form of the first aspect, the engine comprises two or more turbochargers, wherein the control unit is configured to switch off one or more of the two or more turbochargers to maximize the pressure delivered by the compressor in a partial load state of the engine, the control unit preferably being configured to switch off one or more of the two or more turbochargers in dependence of the engine load.

[0039] In a further possible implementation form of the first aspect, a switching point for switching off one or more of the two or more turbochargers is placed in a range of 60% to 80% of the engine load, and the controller is configured to switch off one or more of the two or more turbochargers when the engine load is below the switching point. Additional turbochargers can be added similarly.

[0040] In a further possible implementation form of the first aspect, the controller is operably coupled to a first electronically controlled valve for controlling the amount of scavenging air taken from the intake system, and / or the controller is operably coupled to a second electronically controlled valve for controlling the amount of exhaust gas taken from the exhaust system.

[0041] In a further possible implementation form of the first aspect, the partial engine load covers a range of 20% to 80% of a maximum continuous rating of the engine.

[0042] In a further possible implementation form of the first aspect, the controller is configured to reduce the amount of bypass pressurized gas supplied to the consumer device when the sensed scavenging pressure is below a scavenging pressure threshold, the scavenging pressure threshold being preferably adjusted in dependence of ambient conditions.

[0043] In a further possible implementation form of the first aspect, the controller is configured to reduce the amount of bypass pressurized gas supplied to the consumer device when the sensed exhaust gas temperature is above an exhaust gas temperature threshold, the exhaust gas temperature threshold being preferably adjusted in dependence of ambient conditions.

[0044] In a further possible implementation form of the first aspect, the partial engine load covers a range of 20% to 800% of a maximum continuous rating of the engine.

[0045] In a further possible implementation form of the first aspect, the engine comprises a pressure sensor for sensing a scavenging pressure in the intake system, preferably in or immediately upstream of the scavenging receiver, and / or a temperature sensor in the exhaust system for sensing an exhaust gas temperature in the exhaust system, preferably in or immediately downstream of the exhaust receiver, and / or an observer for estimating a scavenging pressure in the intake system, preferably in or immediately upstream of the scavenging receiver, and / or an observer for estimating a temperature in the exhaust system, preferably in or immediately downstream of the exhaust receiver.

[0046] According to a second aspect, there is provided a method of operating a single-flow large turbocharged two-stroke internal combustion engine for supplying pressurized scavenging and / or exhaust gas from the engine to a pressurized gas consumer device, the engine comprising:

[0047] a plurality of cylinders having a scavenging port at a lower end of the cylinder and an exhaust valve at an upper end of the cylinder,

[0048] an intake system through which scavenging is introduced into the cylinder, the intake system comprising a scavenging receiver connected to the cylinder via the scavenging port,

[0049] an exhaust system through which exhaust gas produced in the cylinder is discharged, the exhaust system comprising an exhaust receiver connected to the cylinder via the exhaust valve,

[0050] at least one turbocharger having an exhaust driven turbine with an inlet connected to the exhaust system and a compressor with an outlet connected to the intake system for delivering a pressurized scavenging flow to the intake system,

[0051] a bypass system for supplying a bypassed pressurized gas to the pressurized gas consuming device,

[0052] wherein the bypassed controlled amount of scavenging gas from the intake system or the controlled amount of pressurized exhaust gas from the exhaust system, and

[0053] maximizing the scavenging gas pressure by one or more of:

[0054] maximizing the scavenging gas bypass mass flow:

[0055] - increasing the power output of a turbocharger provided with a turbo hydraulic system,

[0056] - increasing the speed of an auxiliary blower in the intake system of the engine,

[0057] - increasing the speed of an EGR blower in an EGR device of the engine,

[0058] - starting an additional small turbocharger device of the engine,

[0059] - opening a cylinder bypass valve in a cylinder bypass device of the engine,

[0060] - opening an exhaust bypass to a power turbine device of the engine for driving a dedicated electrically driven compressor,

[0061] - starting a hydraulically driven compressor powered by a hydraulic system device of the engine,

[0062] - adjusting the geometry of a variable geometry turbine and thus the turbine flow area of the variable geometry turbine to maximize the pressure delivered by the compressor in the actual operating state of the engine, preferably by reducing the turbine flow area to maximize the pressure delivered by the compressor in the actual operating state of the engine,

[0063] - cutting off one or more of the one or more turbochargers to maximize the pressure delivered by the compressor in a partial load state of the engine, preferably cutting off one or more of the one or more turbochargers depending on the engine load to maximize the pressure delivered by the compressor in a partial load state of the engine,

[0064] - starting one turbocharger below a first cut-off engine load threshold, two turbochargers in an interval between the first and a second cut-off engine load threshold, and three turbochargers above the second cut-off engine load threshold.

[0065] In a possible implementation of the second aspect, the method includes: sensing the scavenging pressure in the intake system, preferably in or immediately upstream of the scavenging receiver; and / or sensing the exhaust temperature in the exhaust system, preferably in or immediately downstream of the exhaust receiver; and adjusting the amount of bypass pressurized gas supplied to the consumption device based on the sensed scavenging pressure and / or exhaust temperature.

[0066] In a possible implementation of the second aspect, the method includes: estimating the scavenging pressure in the intake system, preferably in or immediately upstream of the scavenging receiver; and / or estimating the exhaust temperature in the exhaust system, preferably in or immediately downstream of the exhaust receiver; and adjusting the amount of bypass pressurized gas supplied to the consumption device based on the sensed scavenging pressure and / or exhaust temperature.

[0067] These and other aspects of the invention will become apparent from the embodiments described below. Attached Figure Description

[0068] In the following detailed description of this disclosure, the invention will be described in more detail with reference to the exemplary embodiments shown in the accompanying drawings, in which:

[0069] Figure 1 This is a front view of a large two-stroke internal combustion engine according to an example embodiment.

[0070] Figure 2 yes Figure 1 A side view of a large two-stroke internal combustion engine.

[0071] Figure 3 It is based on Figure 1 A schematic diagram of a large two-stroke internal combustion engine.

[0072] Figure 4 This is a schematic diagram of an embodiment of a large two-stroke internal combustion engine having multiple turbochargers configured for turbocharger cutoff, and

[0073] Figure 5 This is a schematic diagram of an implementation of a large two-stroke internal combustion engine with a variable geometry turbocharger. Detailed Implementation

[0074] Figure 1 , Figure 2 and Figure 3 A large, low-speed turbocharged two-stroke diesel engine 100 with a crankshaft 8 and a crosshead 9 is shown. Figure 3A schematic view of 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 100 has six in-line cylinders. Large, low-speed, turbocharged, two-stroke diesel engines typically have four to fourteen in-line cylinders 1 carried by a cylinder frame 23, which is carried by an engine frame 11. The engine 100 can for example be used as a main engine in a marine vessel or as a stationary engine in a power plant for operating a generator. The total output of the engine 100 can for example be in the range of 1,000 kW to 110,000 kW.

[0075] The engine 100 is in this example embodiment a two-stroke uniflow type compression ignition engine 100 with scavenge ports 18 at the lower region of the cylinder liner 1 and a central exhaust valve 4 at the top of each cylinder liner 1. However, it is understood that the engine 100 does not need to be compression ignited, but can alternatively be spark ignited. Thus, in the present embodiment the compression pressure of the engine 100 will be sufficiently high for compression ignition, but it is understood that the engine 100 can be operated at a lower compression pressure and ignited by a spark or similar.

[0076] The intake system of the engine 100 comprises a scavenge receiver 2. Scavenge is transferred from the scavenge receiver 2 to the scavenge ports 18 of the individual cylinders 1. The scavenge is compressed by the pistons 10 reciprocating in the cylinder liner 1 between bottom dead center (BDC) and top dead center (TDC). Fuel is injected through fuel valves 50 arranged in the cylinder head 22. Subsequently, combustion occurs and exhaust is produced.

[0077] The exhaust valve 4 is arranged centrally in the cylinder head 22, with a plurality of fuel valves 55 distributed around the central exhaust valve 4. The exhaust valve 4 is actuated by an electric hydraulic exhaust valve actuation system (not shown) controlled by a controller 50. The fuel valves 55 are part of a fuel supply system. The controller 50 can also be configured to control operation of the fuel valves 55.

[0078] When the exhaust valve 4 opens, exhaust flows through the exhaust system, including the exhaust conduits associated with the cylinders 1, into the exhaust receiver 3, and continues through a first exhaust conduit 19 to the turbine 8 of a turbocharger 5 (in embodiments, the engine 100 is provided with a plurality of turbochargers 5), from which the exhaust flows through a second exhaust conduit via an economizer 20 to an outlet 21, and then into the atmosphere.

[0079] The turbine 8 drives, through a shaft, a compressor 7 supplied with fresh air via an air inlet 12. The compressor 7 delivers pressurized scavenge to a scavenge conduit 13 leading to the scavenge receiver 2. The scavenge in the scavenge conduit 13 is passed through an intercooler 14 for cooling the scavenge.

[0080] The cooled scavenging air is passed through an auxiliary blower 16 driven by an electric motor 17. This auxiliary blower 16 pressurizes the scavenging air stream when the turbocharger 5 compressor 7 does not deliver sufficient pressure to the scavenging air receiver 2, i.e., when the engine 100 is under low or partial load. Under higher engine load conditions, when the turbocharger compressor 7 delivers sufficient compressed scavenging air, the stopped auxiliary blower 16 is bypassed via a one-way valve 15.

[0081] Reference Figure 4 and Figure 5 In this embodiment, the large marine engine 100, i.e., the single-flow large turbocharged two-stroke internal combustion engine 100, is configured to supply pressurized scavenging air and / or exhaust gas to the pressurized gas consumption device 200. In this embodiment, for simplicity, corresponding structures and features that are identical or similar to those previously described or shown herein are indicated by the same reference numerals as previously used. The compressed air consumption device 200 may, for example, be an air lubrication system for a marine vessel in which the large marine engine 100 is installed to reduce drag when the vessel moves in water.

[0082] Scavenging air is introduced into cylinder 1 through an intake system, which includes a scavenging air receiver 2 connected to cylinder 1 via a scavenging air port 18.

[0083] The exhaust gas generated in the cylinder is discharged through an exhaust system, which includes an exhaust receiver 3 connected to the cylinder 1 via an exhaust valve 4.

[0084] The bypass system supplies bypassed pressurized gas to the pressurized gas consumer 200 by taking a controlled amount of scavenging gas from the intake system, thereby bypassing the engine 100. Here, the first bypass conduit 43 is connected to the intake system at a location downstream of the outlet of the compressor 7, e.g. at the location shown on the scavenging receiver 2. In embodiments, the first bypass conduit 43 comprises a first bypass control valve 41 and is connected to the pressurized gas consumer 200. In embodiments, the first bypass conduit 43 comprises a first bypass blower 47 (compressor). The first bypass blower 47 is activated when the amount of pressurized air supplied by the engine 100 without the support of the first bypass blower 47 is insufficient to meet the demand of the pressurized gas consumer 200. Preferably, both or either of the first bypass control valve 41 and the first bypass blower 47 are controlled by the controller 50. The bypass conduit comprising the first one-way valve 45 allows bypassing the first bypass blower 47 when the support of the first bypass blower 47 is not needed. A pressure sensor 34 for sensing the pressure in the intake system downstream of the compressor 7 is arranged in the intake system and a signal from the pressure sensor 34 is transmitted to the controller 50, e.g. via a signal line. The pressure sensor 34 can also be located in or immediately upstream of the scavenging receiver 2. Alternatively, an observer (not shown in the figures, in embodiments can be part of the controller 50) for estimating the pressure in the intake system, e.g. the pressure in the scavenging receiver, can be used to determine the pressure for use by the controller 50.

[0085] Alternatively or in combination, the bypass system withdraws a controlled amount of pressurized exhaust gas from the exhaust system, thereby bypassing the turbine. Here, the second bypass conduit 49 is connected to the exhaust system at a location upstream of the inlet of the turbine 8, for example as shown at the exhaust receiver 3. In embodiments, the second bypass conduit 49 comprises a second bypass control valve 42 and is connected to the pressurized gas consumer 200. In embodiments, the second bypass conduit 49 comprises a second bypass blower 46 (compressor). The second bypass blower 46 is activated when the amount of pressurized air supplied by the engine 100 without the support of the second bypass blower 46 is insufficient to meet the demand of the pressurized gas consumer 200. The bypass conduit comprising a second one-way valve 44 allows bypassing the second bypass blower 46 when the support of the second bypass blower 46 is not needed. Preferably, both or either of the second bypass control valve 42 and the second bypass blower 46 are controlled by the controller 50. A temperature sensor 33 for sensing the temperature upstream of the turbine 8 in the exhaust system is arranged in the exhaust system and a signal from the temperature sensor 33 is transmitted to the controller 50, for example over a signal line. The temperature sensor 33 can be arranged such that it senses the temperature in the exhaust receiver 3 or immediately downstream of the exhaust receiver 3. Alternatively, an observer (not shown in the figures, in embodiments can be part of the controller 50) configured to estimate the temperature in the exhaust system can be used to determine the exhaust temperature for use by the controller 50.

[0086] The controller 50 is configured to apply the mentioned adjustment measures to maximize the scavenging pressure supplied by the turbine(s) 7 of the turbocharging system 5.

[0087] The controller 50 is configured to adjust the amount of bypass pressurized gas supplied to the consumer 200 in dependence of the sensed or observed scavenging pressure and / or exhaust temperature, in particular to limit the amount of bypass pressurized gas when the adjustment measures have been applied and the scavenging pressure is below a threshold value and / or the exhaust temperature is above a threshold value.

[0088] The controller 50 is thus configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consumer 200 when the sensed scavenging pressure is below a scavenging pressure threshold value and / or the sensed exhaust temperature is above an exhaust temperature threshold value.

[0089] In one embodiment, the controller 50 is configured to: determine the actual engine turbocharging effect based on the sensed scavenging pressure and / or the sensed exhaust temperature; and limit the amount of bypass pressurized gas supplied to the pressurized gas consumption device 200 based on the determined actual engine turbocharging effect. Preferably, the controller 50 is configured to: limit the amount of bypass pressurized gas supplied to the pressurized gas consumption device 200 when the determined actual engine turbocharging effect is lower than an actual engine turbocharging effect threshold.

[0090] The controller 50 is preferably configured to determine an excess of actual available effect of one or more turbochargers 5 compared to a predetermined minimum engine turbocharge effect threshold, and the controller 50 is also preferably configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consumption device 200 based on the determined excess of available effect of the one or more turbochargers 5.

[0091] In an embodiment, the controller 50 is configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consumption device 200 according to the pressurized gas demand of the pressurized gas consumption device 200. Preferably, the amount of bypass pressurized gas supplied to the pressurized gas consumption device 200 is adjusted in response to a signal from the pressurized gas consumption device 200, provided that the determined available excess does not overflow.

[0092] Preferably, at least within a given engine load range, the one or more turbochargers 5 have a turbocharger effect exceeding a predetermined minimum desired engine turbocharging effect.

[0093] exist Figure 5 In the illustrated embodiment, the one or more turbochargers 5 have turbines 5 with variable geometry turbines 8 that allow adjustment of the turbine flow area. A controller 50 is coupled to the one or more turbochargers 5 for controlling the variable geometry of the turbine 8, and the control unit 50 is configured to adjust the geometry of the turbine 8 to maximize the pressure delivered by the compressor 7 under actual operating conditions of the engine 100, preferably by reducing the turbine flow area to maximize the pressure delivered by the compressor 7 under actual operating conditions of the engine 100.

[0094] exist Figure 4 In one embodiment, the engine 100 includes two or more turbochargers 5, and a controller 50 is configured to shut off one or more of the two or more turbochargers 5 to maximize the pressure delivered by the compressor 7 under partial load conditions of the engine 100. The control unit 50 is preferably configured to shut off one or more of the two or more turbochargers 5 according to the engine load.

[0095] The switching point for turning off one or more of the two or more turbochargers 5 is placed in the range of 60% to 80% of the engine load, and the controller 50 is configured to turn off one or more of the two or more turbochargers 5 when the engine load is below the switching point. The switching point for turbocharger turn off can be optimized (shift to higher engine load) by using different mounting parts or different frame sizes for the turbochargers 5.

[0096] In an embodiment (not shown), the engine 100 comprises two or more turbochargers 5, and the controller 50 is configured to activate one turbocharger 5 when below a first cut-off engine load threshold, so that only one turbocharger 5 with a suitable flow area is running at low engine load. The controller 50 is further configured to activate two turbochargers 5 when in the interval between the first cut-off engine load threshold and a second cut-off engine load threshold, so that the combined flow area of the active turbochargers 5 is suitable for running at medium engine load, and the controller 50 is further configured to activate three turbochargers 5 when above the second cut-off engine load threshold, so that the combined flow area of the active turbochargers 5 is suitable for the operating condition. The sequential activation can be optimized by using turbochargers 5 with different flow areas, and is not limited to 3 turbochargers 5, there can be 4 or more turbochargers 5. The engine operation can be optimized by switching on and off the turbochargers 5 in a certain order, so that only the turbocharger 5 or combination of turbochargers 5 with the most suitable flow area is running at a given load. For example, as the load increases, the turbochargers 5 are switched on respectively, to gradually increase the total turbocharger flow area, until close to maximum engine load, when all turbochargers are active.

[0097] The controller 50 is operably coupled to the first electronically controlled valve 41 for controlling the amount of scavenging air taken from the intake system, and / or the controller 50 is operably coupled to the second electronically controlled valve 42 for controlling the amount of exhaust gas taken from the exhaust system.

[0098] In an embodiment, the controller 50 is configured to reduce the amount of bypass pressurized gas supplied to the consumer 200 when the sensed scavenging pressure is below a scavenging pressure threshold. The scavenging pressure threshold is preferably adjusted according to ambient conditions, with the lowest threshold applied in arctic conditions and the highest scavenging pressure threshold applied in tropical conditions. The appropriate level of scavenging pressure threshold and adjustment of the scavenging pressure threshold is an embodiment based on testing or simulation of the engine 100.

[0099] In an embodiment, the controller 50 is configured to reduce the amount of bypass pressurized gas supplied to the consumer 200 when the sensed exhaust gas temperature is higher than an exhaust gas temperature threshold. The exhaust gas temperature threshold is preferably adjusted according to the ambient temperature, with the lowest exhaust gas temperature applied in arctic conditions and the highest threshold applied in tropical conditions. The appropriate level of the exhaust gas temperature threshold and adjustment of the exhaust gas temperature threshold are based on an embodiment of a test or simulation of the engine 100.

[0100] In Figure 5 In an embodiment, the engine 100 comprises a turbocharger 5 with a variable geometry turbine allowing adjustment of the turbine flow area. The controller 50 is configured to adjust the turbine flow area to maximize the pressure delivered by the compressor 7 in actual operating conditions of the engine 100, preferably by reducing the turbine flow area of all turbochargers in the turbocharger 5 to maximize the pressure delivered by the compressor 7 in partial load conditions of the engine 100. In this embodiment, the engine 100 is configured with an optional exhaust gas recirculation (EGR) system comprising an EGR unit 60, an EGR blower 29 and an EGR valve 32. The EGR blower 29 and the EGR valve 32 are electronically controlled under the instructions of the controller 50. The EGR unit 60 comprises elements for processing the recirculated exhaust gas, such as an EGR cooler 62 and / or a scrubber and water mist trap 63.

[0101] In an embodiment, the controller 50 is configured to operate the engine 100 in such a way that the PTI (Power Take In) function of the THS (Turbine Hydraulic System) device on the one or more turbochargers 5 is controlled to maximize the scavenge pressure and / or to maximize the scavenge bypass mass flow.

[0102] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that the auxiliary blower device 16 is controlled to perform additional pressurization at higher than usual loads, to maximize the scavenge pressure and / or to maximize the scavenge bypass mass flow.

[0103] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that the high turbocharging effect of a two-stage turbocharger device is used, to maximize the scavenge pressure and / or to maximize the scavenge bypass mass flow.

[0104] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that the cylinder bypass valve device is controlled to be pressurized, to maximize the scavenge pressure.

[0105] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that the function of the EGR blower 29 in the EGR device on a Tier 3 EGR engine 100 is controlled to add boost in Tier 2 mode, maximizing exhaust bypass pressure.

[0106] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that an additional turbocharger device is controlled to add boost to additional ambient air or bypass scavenging, maximizing delivered gas pressure.

[0107] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that an exhaust bypass to the power turbine device is controlled for driving a dedicated additional electric compressor, maximizing delivered gas pressure.

[0108] In another embodiment, the controller 50 is configured to operate the engine 100 in such a way that a hydraulic drive compressor powered by the engine's hydraulic system device is controlled to maximize delivered gas pressure and / or mass flow.

[0109] The engine 100 is operated according to a method comprising bypassing a controlled amount of scavenging air from the intake system or a controlled amount of pressurized exhaust gas from the exhaust system. The scavenging air pressure in the intake system is sensed, and / or the exhaust gas temperature in the exhaust system is sensed. The amount of bypass pressurized gas supplied to the consumer 200 is adjusted according to the sensed scavenging air pressure and / or exhaust gas temperature.

[0110] The various measures to optimize engine performance shown in the above embodiments can be combined, for example by combining sequential turbocharging (turbo cut-off) with adjustment of the turbine flow area of one or more variable geometry turbochargers.

[0111] The methods and engines have been described in connection with various embodiments herein. However, persons skilled in the art will recognize immediately upon consideration of the drawings, this disclosure and the appended claims that changes and modifications of the disclosed embodiments can be understood and effected. 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 controller or other unit can carry out the functions of several items listed in the claims. The combination of measures recited in mutually different dependent claims do not exclude that each of the measures can be used independently. The reference signs in the claims should not be construed as limiting the scope.

Claims

1. A single-flow large turbocharged two-stroke internal combustion engine (100) configured to supply a pressurized charge of scavenging and / or exhaust gas to a pressurized gas consumer (200), the engine (100) comprising: - a plurality of cylinders (1) having a scavenging port (18) at a lower end of the cylinder (1) and an exhaust valve (4) at an upper end of the cylinder (1), - an intake system through which scavenging is introduced into the cylinder (1), the intake system comprising a scavenging receiver (2) connected to the cylinder (1) via the scavenging port (18), - an exhaust system through which exhaust gas produced in the cylinder is discharged, the exhaust system comprising an exhaust receiver (3) connected to the cylinder (1) via the exhaust valve (4), - one or more turbochargers (5) each having an exhaust-driven turbine (8) operatively coupled to a compressor (7), an inlet of the turbine (8) being connected to the exhaust system, and an outlet of the compressor (7) being connected to the intake system for delivering a pressurized scavenging flow to the intake system, - a fuel system for delivering fuel to the cylinder (1), - a bypass system for supplying a bypassed pressurized gas to the pressurized gas consumer (200) by taking a controlled amount of scavenging from the intake system, bypassing the engine (100), and / or by taking a controlled amount of pressurized exhaust gas from the exhaust system, bypassing the turbine (8), - a controller (50) coupled to a pressure sensor (34) and / or a temperature sensor (33), the controller (50) being configured to adjust the amount of bypassed pressurized gas supplied to the pressurized gas consumer (200) as a function of the sensed scavenging pressure and / or exhaust temperature, - wherein the controller (50) is configured to operate the engine (100) in one or more of the following ways to maximize the scavenging bypass mass flow: - increasing the speed of an auxiliary blower (16) in the intake system of the engine (100), - increasing the speed of an exhaust gas recirculation blower (29) in an exhaust gas recirculation device of the engine (100), - starting an additional small turbocharger device of the engine (100), - opening a cylinder bypass valve in a cylinder bypass device of the engine (100), - opening an exhaust gas bypass to a power turbine device of the engine (100) for driving a dedicated electrically driven compressor, - starting a hydraulically driven compressor located in the intake system, the hydraulically driven compressor being powered by a hydraulic system of the engine (100), - cutting off one or more of the turbochargers (5) to maximize the pressure delivered by the compressor (7) in a partial load state of the engine (100). - starting one turbocharger (5) below a first cut-off engine load threshold, starting two turbochargers (5) in an interval between the first cut-off engine load threshold and a second cut-off engine load threshold, and starting three turbochargers (5) above the second cut-off engine load threshold.

2. The engine (100) of claim 1, wherein, The controller (50) is configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) when the sensed or observed scavenging pressure is below a scavenging pressure threshold and / or the sensed exhaust gas temperature is above an exhaust gas temperature threshold.

3. The engine (100) of claim 1 or 2, wherein, The controller (50) is configured to determine an actual engine turbocharging effect from the sensed or observed scavenging pressure and / or the sensed / observed exhaust gas temperature.

4. The engine (100) of claim 3, wherein, The controller (50) is configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) from the determined actual engine turbocharging effect.

5. The engine (100) of claim 4, wherein, The controller (50) is configured to reduce the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) when the determined actual engine turbocharging effect is below an actual engine turbocharging effect threshold.

6. The engine (100) of claim 1, wherein, The controller (50) is configured to determine an actual available effect excess of the one or more turbochargers (5) compared to a predetermined minimum engine turbocharging effect threshold.

7. The engine (100) of claim 6, wherein, The controller (50) is configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) from the determined actual available effect excess of the one or more turbochargers (5).

8. The engine (100) of claim 1, wherein, The controller (50) is configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) from a pressurized gas demand of the pressurized gas consuming device (200).

9. The engine (100) of claim 1, wherein, The one or more turbochargers (5) have a turbocharger effect exceeding a predetermined minimum required engine turbocharging effect at least in a given engine load range.

10. The engine (100) of claim 1, wherein, A switching point for cutting off one or more of the two or more turbochargers (5) is placed in a range of 60% to 80% of an engine load, and the controller (50) is configured to cut off one or more of the two or more turbochargers (5) when the engine load is below the switching point.

11. The engine (100) of claim 1, wherein, The controller (50) is operatively coupled to a first electronically controlled valve (41) for controlling an amount of scavenging air taken from the intake system and / or the controller (50) is operatively coupled to a second electronically controlled valve (42) for controlling an amount of exhaust gas taken from the exhaust system.

12. The engine (100) of claim 1, wherein, The controller (50) is configured to reduce the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) when the sensed scavenging pressure is below a scavenging pressure threshold.

13. The engine (100) of claim 1, wherein, The controller (50) is configured to reduce the amount of bypassed pressurized gas supplied to the pressurized gas consuming device (200) when the sensed exhaust gas temperature is higher than an exhaust gas temperature threshold.

14. The engine (100) of claim 1, wherein, The engine (100) comprises a pressure sensor (34) for sensing the scavenge pressure in the intake system and / or a temperature sensor (33) in the exhaust system for sensing the exhaust gas temperature in the exhaust system and / or an observer for estimating the scavenge pressure in the intake system and / or an observer for estimating the temperature in the exhaust system.

15. A method of operating a single-flow large turbocharged two-stroke internal combustion engine (100) for supplying pressurized scavenge gas and / or exhaust gas from the engine (100) to a pressurized gas consuming device (200), the engine (100) comprising: a plurality of cylinders (1) having scavenge ports (18) at a lower end of the cylinders (1) and exhaust valves (4) at an upper end of the cylinders (1), an intake system through which scavenge gas is introduced into the cylinders (1), the intake system comprising a scavenge receiver (2) connected to the cylinders (1) via the scavenge ports (18), an exhaust system through which exhaust gas produced in the cylinders is discharged, the exhaust system comprising an exhaust receiver (3) connected to the cylinders (1) via the exhaust valves (4), one or more turbochargers (5) having an exhaust driven turbine (8) operatively coupled to a compressor (7), an inlet of the turbine (8) being connected to the exhaust system and an outlet of the compressor (7) being connected to the intake system for delivering a pressurized scavenge gas flow to the intake system, a bypass system for supplying bypassed pressurized gas to the pressurized gas consuming device (200), wherein a bypass controlled amount of scavenge gas from the intake system or a controlled amount of pressurized exhaust gas from the exhaust system, and maximizing the scavenge gas bypass mass flow by one or more of: - increasing the speed of an auxiliary blower (16) in the intake system of the engine (100), - increasing the speed of an exhaust gas recirculation blower (29) in an exhaust gas recirculation device of the engine (100), - activating an additional small turbocharger device of the engine (100), - opening a cylinder bypass valve in a cylinder bypass device of the engine (100), - opening an exhaust gas bypass to a power turbine device of the engine (100) for driving a dedicated electrically driven compressor, - increasing the speed of an electrically driven compressor of the engine (100). - starting a hydraulic drive compressor located in the intake system, the hydraulic drive compressor being powered by a hydraulic system of the engine (100), - cutting off one or more of the turbochargers (5) to maximize the pressure delivered by the compressor (7) in partial load conditions of the engine (100), - starting one turbocharger (5) below a first cut-off engine load threshold, two turbochargers (5) in an interval between the first cut-off engine load threshold and a second cut-off engine load threshold, and three turbochargers (5) above the second cut-off engine load threshold.

16. The method of claim 15, wherein, The method comprises sensing a scavenge pressure in the intake system and / or sensing an exhaust temperature in the exhaust system, and adjusting the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) as a function of the sensed scavenge pressure and / or exhaust temperature.

17. The method of claim 16, wherein, The method comprises estimating a scavenge pressure in the intake system and / or estimating an exhaust temperature in the exhaust system, and adjusting the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) as a function of the sensed scavenge pressure and / or exhaust temperature. The method comprises sensing a scavenge pressure in the intake system and / or sensing an exhaust temperature in the exhaust system, and adjusting the amount of bypass pressurized gas supplied to the pressurized gas consuming device (200) as a function of the sensed scavenge pressure and / or exhaust temperature.

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