Engine, method of operating the same and marine vessel

Abstract

A single-flow, large turbocharged two-stroke internal combustion engine (100), a method for operating the engine (100) and a marine vessel (210) comprising the engine (100). The engine (100) is configured to deliver mechanical energy to the marine vessel (210) and to deliver air at a desired pressure to an air lubrication system (200) of the marine vessel (210). The engine (100) comprises an air supply conduit (49) connecting an air intake system of the engine (100) to the air lubrication system (200). The air supply conduit (49) comprises a blower (44) and a throttle valve (48), or the blower is a centrifugal blower adapted to be rotated by wind power. When the air lubrication system (200) is in operation, all air supplied by the engine (100) to the air lubrication system (200) is passed through a compressor.

Description

Technical Field

[0001] This disclosure relates to a large turbocharged two-stroke internal combustion engine configured to deliver mechanical energy for the propulsion of marine vessels and configured to supply pressurized air for use in the air lubrication system of marine vessels. Background Technology

[0002] Large turbocharged two-stroke internal combustion engines are commonly used as the main engines in the propulsion systems of large ships or as prime movers in power plants. The sheer size, weight, and power output of large turbocharged two-stroke internal combustion engines distinguish them entirely from ordinary combustion engines, classifying them as a separate category. The height of these engines is generally not critical, so they are constructed with a crosshead to avoid lateral loads on the piston. Typically, these engines operate on ammonia, natural gas, LPG, methanol, ethane, or fuel oil.

[0003] Large, turbocharged, two-stroke internal combustion engines used for ship propulsion are tuned to support certain fuel-saving systems installed on ships. In particular, waste heat recovery systems are crucial for reducing the overall energy consumption of marine ship engines and reducing emissions from them.

[0004] In some applications, the main engine needs to supply pressurized air in addition to providing mechanical energy (e.g., for propulsion). Air lubrication is one such application. Marine vessels with large, flat bottom areas can utilize air lubrication to reduce drag when moving through water, thereby reducing the main engine power required to propel the vessel at a given speed. The pressurized air outlet of the air lubrication system is connected to one or more chambers in the bottom of the hull, as well as to the engine at the vessel's current draft, supplying air at hydrostatic pressure in each chamber. The air lubrication system pumps a steady stream of air bubbles beneath the hull of the marine vessel to reduce frictional drag between the hull and the surrounding water.

[0005] To reduce the power required for ship propulsion, sufficient pressure and quantity of air / gas need to be supplied to a dedicated bubble generator interface, depending on the ship's draft. Large two-stroke engines often struggle to provide adequate pressurized air / gas at all engine loads, especially at low loads. It is known that, under given operating conditions, when the pressure supplied by the engine is insufficient, an electrically driven blower can be used to increase the air pressure, and when the engine-supplied gas pressure is sufficient, a bypass line can be opened to bypass the blower.

[0006] When load changes are possible, switching the air lubrication flow control from the main engine to the blower (or from the blower to the main engine) will dynamically affect the bypass flow and pressure during the transition and carries the risk of causing uncontrollable pressure fluctuations in the piping system, which could lead to unexpected engine shutdown or even have adverse effects on the operation of the main engine.

[0007] CN115199401A discloses a single-flow, large-scale turbocharged two-stroke internal combustion engine and a method of operating the engine, wherein the engine is configured to supply pressurized scavenging gas and / or exhaust gas to a pressurized gas consumption device. The engine includes: a plurality of cylinders; an air intake system; an exhaust system; one or more turbochargers having turbines; a fuel system; a bypass system for bypassing the engine by drawing a controllable amount of scavenging gas from the intake system to supply bypass pressurized gas to the pressurized gas consumption device, and / or by drawing a controllable amount of pressurized exhaust gas from the exhaust system to supply bypass pressurized gas to the pressurized gas consumption device, thereby bypassing the turbines; and a controller configured to adjust the amount of bypass pressurized gas supplied to the consumer based on sensed scavenging pressure and / or exhaust temperature. The controller is configured to operate the engine in a manner that takes various adjustment measures to maximize scavenging pressure and / or maximize scavenging bypass mass flow rate. Summary of the Invention

[0008] The object of the present invention is to provide a single-flow, large-scale turbocharged two-stroke internal combustion engine that overcomes or at least reduces the problems described above.

[0009] The foregoing and other objectives are achieved by the features of the independent claims. Further implementations are apparent from the dependent claims, the specification, and the figures.

[0010] According to a first aspect, a single-flow, large-scale turbocharged two-stroke internal combustion engine is provided for propelling marine vessels, the engine being configured to supply pressurized scavenging air at a desired mass flow rate and pressure to the air lubrication system of the marine vessel, the engine comprising: Multiple cylinders, each with a scavenging port and a discharge valve. The intake system, through which scavenging air is introduced into the cylinder, includes a scavenging air receiver connected to the cylinder via a scavenging port. The exhaust system, through which exhaust gases generated in the cylinder are discharged, includes an exhaust gas receiver connected to the cylinder via an exhaust valve. At least one turbocharger, the at least one turbocharger having an exhaust gas-driven turbine operably coupled to a compressor, and the turbine being disposed in an exhaust system and the compressor being disposed in an intake system, for delivering a pressurized scavenging air stream at scavenging pressure to a scavenging air receiver. The lubricating air supply line is used to supply pressurized air from the intake system to the air lubrication system. A blower, installed in the supply line and driven by a motor, includes an air inlet and an air outlet, and... Or: i) A throttle valve is located upstream of the blower in the supply line, and the controller is configured to: If the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line, adjust the position of the throttle valve to reduce the pressure at the blower's air inlet to a level lower than the sum of the desired pressure and the pressure loss downstream of the blower along the air supply line. When the air lubrication system is running, the blower is continuously driven by the motor, and all the air supplied from the engine to the air lubrication system passes through the blower. Or: ii) A throttle valve is located downstream of the blower in the supply line, and the controller is configured to: When the air lubrication system is running, the blower is continuously driven by the motor, and all the air supplied from the engine to the air lubrication system passes through the blower, thereby increasing the air pressure in the air supply line. Adjust the position of the throttle valve to obtain the desired mass flow rate.

[0011] By providing an air supply line consisting of only a single line, and a blower and throttle valve that ensure the blower always needs to perform positive pumping action, an air supply from the engine to the air lubrication system is obtained, which does not require bypasses and associated valves with the aforementioned problems.

[0012] According to a possible implementation of the first aspect, the engine includes i), wherein the controller is configured to continuously drive the blower by a motor at a speed sufficient to provide the desired mass flow rate.

[0013] According to a possible implementation of the first aspect, the engine includes i), wherein the controller is configured to adjust the position of the throttle valve to reduce the pressure at the air inlet of the blower to a level below the desired pressure.

[0014] According to a possible implementation of the first aspect, the engine includes i), wherein the controller is configured to receive a setpoint signal representing the desired mass flow rate.

[0015] According to a possible implementation of the first aspect, the engine includes i), and wherein a second pressure P2 is measured by a second sensor, the second sensor being configured to provide a second signal representing the air pressure P2 at the air inlet of the blower, and wherein a controller is configured to receive the second signal of the second pressure P2 measured by the second sensor and a signal of a third pressure P3 measured by a third sensor, the third sensor being configured to provide a third signal representing the air pressure P3 at the air outlet of the blower 44.

[0016] According to a possible implementation of the first aspect, the engine includes i), wherein the controller is configured to cause the blower to operate at at least a minimum operating speed when the air lubrication system is running.

[0017] According to a possible implementation of the first aspect, the engine includes i), wherein the controller is configured to adjust the position of the throttle valve to increase the degree of throttling when the mass flow rate to the air lubrication system is higher than the desired mass flow rate and the blower is running at a minimum operating speed.

[0018] According to a possible implementation of the first aspect, the controller is configured to open the throttle valve to the fully open position when the scavenging pressure is lower than the sum of the desired pressure and the pressure loss along the air supply line.

[0019] According to a possible implementation of the first aspect, the controller is configured to increase the speed of the blower when the throttle valve is in the fully open position and the mass flow rate is lower than the desired mass flow rate.

[0020] According to a possible implementation of the first aspect, the intake system includes an intercooler between the compressor and the scavenging air receiver, and an inlet of a lubricating air supply line connected to the intake system at a location downstream of the intercooler.

[0021] According to a possible implementation of the first aspect, the engine includes only a single lubricating air supply line.

[0022] According to a possible implementation of the first aspect, the engine comprises only a single blower.

[0023] According to the possible implementation of the first aspect, the engine does not include a blower bypass line.

[0024] According to a possible implementation of the first aspect, the lubricating air supply line includes a water mist trap located between the throttle valve and the blower.

[0025] According to a possible implementation of the first aspect, the engine includes ii, wherein the blower has a minimum operating speed, the throttle valve is movable between a minimum throttle position and a maximum throttle position, in the minimum throttle position the throttle valve applies minimum throttle, and in the maximum throttle position the throttle valve applies maximum throttle, and the controller is configured to: Move the throttle valve to the position where the mass flow rate corresponds to the desired mass flow rate. When the throttle valve applies a greater throttling force than it would at the minimum throttling position, the blower speed is reduced towards the minimum operating speed. When the throttle valve is in the minimum throttle position and the mass flow rate is lower than the desired mass flow rate, increase the speed of the blower.

[0026] According to the second aspect, a marine vessel is provided, comprising an air lubrication system and an engine according to the first aspect or any possible implementation thereof.

[0027] According to a third aspect, a method is provided for operating a single-flow, large-scale turbocharged two-stroke internal combustion engine for propelling marine vessels, the engine being configured to supply pressurized scavenging air at a desired mass flow rate and pressure to the air lubrication system of the marine vessel, the engine comprising: Multiple cylinders, each with a scavenging port and a discharge valve. The intake system, through which scavenging air is introduced into the cylinder, includes a scavenging air receiver connected to the cylinder via a scavenging port. The exhaust system, through which exhaust gases generated in the cylinder are discharged, includes an exhaust gas receiver connected to the cylinder via an exhaust valve. At least one turbocharger, the at least one turbocharger having an exhaust gas-driven turbine operably coupled to a compressor, and the turbine being disposed in an exhaust system and the compressor being disposed in an intake system, for delivering a pressurized scavenging air stream at scavenging pressure to a scavenging air receiver. The lubricating air supply line is used to supply pressurized air from the intake system to the air lubrication system. A blower, installed in the supply line and driven by a motor, includes an air inlet and an air outlet, and Or: A throttle valve is installed upstream of the blower in the supply line, and the method includes: If the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line, the position of the throttle valve is adjusted to reduce the pressure at the blower's air inlet to a level lower than the sum of the desired pressure and the pressure loss downstream of the blower along the air supply line. When the air lubrication system is running, the blower is continuously driven by the motor, and all the air supplied from the engine to the air lubrication system passes through the blower. Or: A throttle valve is installed downstream of the blower in the supply line. When the air lubrication system is running, the blower is continuously driven by the motor, and all the air supplied from the engine to the air lubrication system passes through the blower, thereby increasing the air pressure in the air supply line. Adjust the position of the throttle valve to obtain the desired mass flow rate.

[0028] According to a possible implementation of the third aspect, the method includes: opening the throttle valve to the fully open position when the scavenging pressure is lower than the sum of the desired pressure and the pressure loss along the air supply line.

[0029] According to a possible implementation of the third aspect, the method includes: increasing the speed of the blower when the throttle valve is in the fully open position and the mass flow rate is lower than the desired mass flow rate.

[0030] According to a possible implementation of the third aspect, the engine includes ii), wherein the blower has a minimum operating speed, and the throttle valve is movable between a minimum throttle position and a maximum throttle position, wherein in the minimum throttle position the throttle valve applies minimum throttle, and in the maximum throttle position the throttle valve applies maximum throttle, the method comprising: Move the throttle valve to the position where the mass flow rate corresponds to the desired mass flow rate. When the throttle valve applies a greater throttling force than it would at the minimum throttling position, the blower speed is reduced towards the minimum operating speed. When the throttle valve is in the minimum throttle position and the mass flow rate is lower than the desired mass flow rate, increase the speed of the blower.

[0031] According to a fourth aspect, a single-flow, large-scale turbocharged two-stroke internal combustion engine for propelling marine vessels is provided, the engine being configured to supply pressurized scavenging air at a desired pressure and a desired mass flow rate to the air lubrication system of the marine vessel, the engine comprising: Multiple cylinders, each with a scavenging port and a discharge valve. The intake system, through which scavenging air is introduced into the cylinder, includes a scavenging air receiver connected to the cylinder via a scavenging port. An exhaust system is used to discharge exhaust gases generated in the cylinder. This exhaust system includes an exhaust gas receiver connected to the cylinder via an exhaust valve. At least one turbocharger, the at least one turbocharger having an exhaust gas-driven turbine operably coupled to a compressor, and the turbine being disposed in an exhaust system and the compressor being disposed in an intake system, for delivering a pressurized scavenging air stream at scavenging pressure to a scavenging air receiver. The lubricating air supply line is used to supply pressurized air from the intake system to the air lubrication system. A blower, which is installed in the supply line and driven by a motor, includes an air inlet and an air outlet, and a controller is configured to: When the scavenging pressure is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line, the centrifugal blower is driven by a motor. When the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line, the centrifugal blower is allowed to rotate by airflow.

[0032] By providing an air supply line consisting of only a single conduit and a blower configured to rotate by wind power, an air supply from the engine to the air lubrication system is obtained, which requires no bypass and has associated valves with the problems mentioned above.

[0033] According to a possible implementation of the fourth aspect, the engine includes a throttle valve disposed upstream of the blower in the supply line, wherein the controller is configured to adjust the position of the throttle valve to reduce the mass flow rate when the centrifugal blower is allowed to rotate by air force and the mass flow rate is higher than the desired mass flow rate.

[0034] According to a possible implementation of the fourth aspect, the controller is configured to adjust the position of the throttle valve to the open position when the centrifugal blower is driven by the motor.

[0035] According to a possible implementation of the fourth aspect, the controller is configured to increase the operating speed of the centrifugal blower when the throttle valve is in the open position and the mass flow rate is lower than the desired mass flow rate.

[0036] According to a possible implementation of the fourth aspect, the centrifugal blower includes variable diffuser blades, and the centrifugal blower is configured such that when the centrifugal blower is allowed to rotate by wind power, the position of the diffuser blades is adjusted to obtain the desired mass flow rate.

[0037] According to a possible implementation of the fourth aspect, the centrifugal blower includes an active magnet support.

[0038] According to a possible implementation of the fourth aspect, the controller is configured to adjust the position of the throttle valve to enhance its throttling effect when the centrifugal blower rotates by air force and the mass flow rate is higher than the desired mass flow rate.

[0039] According to a possible implementation of the fourth aspect, the controller is configured to receive a setpoint signal that represents the desired mass flow rate.

[0040] According to a possible implementation of the fourth aspect, the engine includes a first pressure sensor configured to provide a first signal representing the pressure P of the scavenging air supplied to the scavenging air receiver, wherein a controller is configured to receive the first signal, and wherein, preferably, the controller is configured to move the throttle valve to the open position when the pressure P of the scavenging air supplied to the scavenging air receiver is lower than the sum of a desired pressure and pressure loss along the air supply line.

[0041] According to a possible implementation of the fourth aspect, the controller is configured to adjust the position of the throttle valve to increase the degree of throttling when the mass flow rate is higher than the desired mass flow rate and the centrifugal blower is rotating by air force.

[0042] According to a possible implementation of the fourth aspect, the controller is configured to: when the mass flow rate is lower than the desired mass flow rate, move the throttle valve to the minimum throttling position of the throttle valve before increasing the speed of the blower to above the minimum operating speed, in order to obtain the desired mass flow rate.

[0043] According to a possible implementation of the fourth aspect, the controller is configured to increase the operating speed of the centrifugal blower to obtain the mass flow rate when the throttle valve is at its minimum throttling position and the mass flow rate is lower than the desired mass flow rate.

[0044] According to a possible implementation of the fourth aspect, the intake system includes an intercooler between the compressor and the scavenging air receiver, and an inlet of the lubricating air supply line connected to the intake system at a location downstream of the intercooler.

[0045] According to a possible implementation of the fourth aspect, the engine includes only a single lubricating air supply line.

[0046] According to a possible implementation of the fourth aspect, the lubricating air supply line includes only a single centrifugal blower.

[0047] According to the possible implementation of the fourth aspect, the engine does not include a blower bypass line.

[0048] According to a possible implementation of the fourth aspect, the controller is configured to shut off the motor when the centrifugal blower is allowed to rotate by airflow.

[0049] According to a possible implementation of the fourth aspect, the controller is configured to: when the centrifugal blower rotates by wind power, use the motor as a generator to generate a load on the centrifugal blower, thereby increasing the pressure difference on the centrifugal blower to obtain the desired mass flow rate.

[0050] According to the fifth aspect, a marine vessel is provided, comprising an air lubrication system and an engine according to the fourth aspect or any possible implementation thereof.

[0051] According to a sixth aspect, a method is provided for operating a single-flow, large-scale turbocharged two-stroke internal combustion engine for propelling a marine vessel, the engine being configured to supply pressurized scavenging air at a desired mass flow rate and pressure to the air lubrication system of the marine vessel, the engine comprising: Multiple cylinders, each with a scavenging port and a discharge valve. The intake system, through which scavenging air is introduced into the cylinder, includes a scavenging air receiver connected to the cylinder via a scavenging port. An exhaust system is provided for discharging exhaust gases generated in the cylinder. This exhaust system includes an exhaust gas receiver connected to the cylinder via an exhaust valve. At least one turbocharger, the at least one turbocharger having an exhaust gas-driven turbine operably coupled to a compressor, and the turbine being disposed in an exhaust system and the compressor being disposed in an intake system, for delivering a pressurized scavenging air stream at scavenging pressure to a scavenging air receiver. The lubricating air supply line is used to supply pressurized air from the intake system to the air lubrication system. A blower, installed in the supply line and driven by a motor, includes an air inlet and an air outlet, and The methods include: When the scavenging pressure is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line, the centrifugal blower is driven by a motor. When the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line, the centrifugal blower is allowed to rotate by airflow.

[0052] According to a possible implementation of the sixth aspect, the engine includes a throttle valve disposed upstream of the blower in the supply line, and the method includes adjusting the position of the throttle valve to reduce the mass flow rate when the centrifugal blower is rotating by air force and the mass flow rate is higher than the desired mass flow rate.

[0053] According to a possible implementation of the sixth aspect, the method includes: when the centrifugal blower is driven by a motor, adjusting the position of the throttle valve to the open position.

[0054] According to a possible implementation of the sixth aspect, the method includes: increasing the operating speed of the centrifugal blower when the throttle valve is in the open position and the mass flow rate is lower than the desired pressure.

[0055] According to a possible implementation of the sixth aspect, the method includes: when the centrifugal blower rotates by wind power, the motor operates as a generator to generate a load on the centrifugal blower, thereby increasing the pressure difference on the centrifugal blower to obtain the desired mass flow rate.

[0056] These and other aspects of the invention will become apparent from the embodiments described below. Attached Figure Description

[0057] In the following detailed sections of this disclosure, the invention will be described in more detail with reference to the exemplary embodiments shown, wherein: Figure 1 This is a front top view of a large two-stroke internal combustion engine according to an exemplary embodiment.

[0058] Figure 2 yes Figure 1 A top-side view of a large two-stroke internal combustion engine.

[0059] Figure 3 It is based on Figure 1 A schematic diagram of a large two-stroke internal combustion engine.

[0060] Figure 4 It has air supply lines and an air lubrication system. Figures 1 to 3 A schematic diagram illustrating the implementation of a large two-stroke internal combustion engine.

[0061] Figure 5a and Figure 5b This is a diagram showing the pressure P along the length L of the air supply line from the engine's intake system to the air lubrication system.

[0062] Figure 6 It shows including Figures 1 to 4 Marine vessels with engines and air lubrication systems.

[0063] Figure 7It has air supply lines and an air lubrication system. Figures 1 to 3 A schematic diagram of another embodiment of a large two-stroke internal combustion engine, and Figure 8a and Figure 8b A diagram showing the pressure P along the length L of the air supply line from the engine's intake system to the air lubrication system is presented. Detailed Implementation

[0064] Figures 1 to 4 A first embodiment of a large, low-speed turbocharged two-stroke internal combustion engine 100 with a crankshaft 8 and a crosshead 9 is shown. Figure 3 A schematic diagram of a large, low-speed, turbocharged two-stroke internal combustion engine and its intake and exhaust systems is shown. Figure 4 A schematic diagram of a large, low-speed, turbocharged, two-stroke internal combustion engine, its intake and exhaust systems, and an air supply line 49 connecting the engine 100's intake system and air lubrication system 200 is shown.

[0065] In this exemplary embodiment, engine 100 has six inline cylinders 1. Large, low-speed, turbocharged two-stroke diesel engines typically have between four and fourteen inline cylinders 1, which are supported by cylinder banks 23, which in turn are supported by engine frames 11. Engine 100 can be used, for example, as a main engine in marine vessels or as a stationary engine operating a generator in a power plant. For example, the total output power of engine 100 can be in the range of 1,000 kW to 110,000 kW.

[0066] In this example, engine 100 is a two-stroke, single-flow compression-ignition engine, which has a scavenging port 18 in the lower region of cylinder liner 1 and a central exhaust valve 4 located at the top of each cylinder liner 1. However, it should be understood that engine 100 is not necessarily compression-ignition, or could alternatively be spark-ignition. Therefore, in this embodiment, the compression pressure of engine 100 will be sufficiently high for compression ignition, but it should be understood that engine 100 can be operated with lower compression pressures and ignited by spark or similar means.

[0067] The intake system of engine 100 includes a scavenging air receiver 2. Scavenging air is delivered from the scavenging air receiver 2 to the scavenging ports 18 of each cylinder 1. The scavenging air is compressed by a piston 10 reciprocating between bottom dead center (BDC) and top dead center (TDC) in the cylinder liner 1. Fuel is injected via a fuel valve 55 located in the cylinder cover 22. Combustion then occurs, producing exhaust gases.

[0068] An exhaust valve 4 is positioned at the center of the cylinder cover 22, and multiple fuel valves 55 are distributed around the central exhaust valve 4. The exhaust valve 4 is actuated by an electro-hydraulic exhaust valve actuation system (not shown) controlled by a controller 50 (electronic control unit). Fuel is supplied to the fuel valves 55 via a fuel supply system 30. The controller 50 is also configured to control the operation of the fuel valves 55.

[0069] When the exhaust valve 4 is open, the exhaust gas flows through the exhaust system, which includes an exhaust pipe associated with the cylinder 1, to the exhaust gas receiver 3, and flows forward through the first exhaust pipe 19 to the turbine 8 of the turbocharger 5 (in an embodiment, the engine 100 is provided with a plurality of turbochargers 5). The exhaust gas flows out of the turbine 8 through the second exhaust pipe via the economizer 20 to the outlet 21 and flows into the atmosphere.

[0070] The turbine 8 drives the compressor 7 via a shaft, and the compressor 7 is supplied with fresh air through the air inlet 12. The compressor 7 delivers the pressurized scavenging air to the scavenging air duct 13 leading to the scavenging air receiver 2. The scavenging air in the scavenging air duct 13 passes through an intercooler 14 for cooling.

[0071] The cooled scavenging air passes through an auxiliary blower 16 driven by an electric motor 17. This auxiliary blower 16 pressurizes the scavenging air stream when the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging receiver 2, i.e., under low or partial load conditions of the engine 100. Under higher load conditions, the compressor 7 delivers fully compressed scavenging air, and then the stopped auxiliary blower 16 passes through a check valve 15.

[0072] The first pressure sensor 34 sends a signal representing the pressure P1 supplied to the scavenging receiver 2 to the controller 50.

[0073] The large marine engine 100, namely the single-flow large turbocharged two-stroke internal combustion engine 100, is configured to supply pressurized scavenging air to the air lubrication system 200.

[0074] 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 port 18.

[0075] The exhaust gas generated by the cylinder is discharged through an exhaust system, which includes an exhaust gas receiver 3 connected to the cylinder 1 via an exhaust valve 4.

[0076] Air supply line 49 bypasses engine 100 by drawing a controllable amount of scavenging air from the intake system to supply pressurized air at a desired pressure and desired mass flow rate to air lubrication system 200. Here, air supply line 49 is connected to the intake system downstream of the compressor 7 outlet; preferably, air supply line 49 is also connected to the intake system downstream of intercooler 14, as... Figure 4 As shown. However, supply line 49 is also connected to scavenging air receiver 2.

[0077] Air supply line 49 includes a blower 44 and a throttle valve 48 and is connected to air lubrication system 200. Blower 44 is driven by electric drive motor 41. The operating speed of AC drive motor 41 is controlled by variable frequency drive (VFD) 40 in response to a signal from controller 50. Blower 44 is preferably a centrifugal blower, but it can also be a different type of blower, such as a positive displacement blower, Roots blower, rotary screw blower, or spiral screw blower.

[0078] The air supply line 49 is also equipped with a water mist trap 43, which is preferably located between the throttle valve 48 and the blower 44.

[0079] A check valve is installed downstream of the blower 44 to prevent air from flowing from the air lubrication system 200 to the intake system.

[0080] The second pressure sensor 42 sends a signal representing the pressure P2 downstream of the throttle valve 48 and upstream of the blower 44 to the controller 50. The third pressure sensor 47 sends a third signal representing the pressure P3 downstream of the blower 44 to the controller 50. This figure illustrates the pressure loss along the air supply line, but for practical reasons and simplicity, only the pressure at one location—between the throttle valve 48 and the blower 44—is measured, and the pressure at the air lubrication system 200 and the blower 44. For example, the pressure at the outlet of the air supply line 49 can be derived from the dimensions of the air supply line 49 and the amplitude of the airflow. Similarly, the pressure at the inlet of the blower 44 can be derived or estimated.

[0081] The second pressure sensor 42 and the third pressure sensor 47 on both sides of the blower 44 allow the controller 50 to determine how much boost pressure the blower 44 is generating. If the pressure ratio on the blower 44 is less than 1.0, that is, when the pressure ratio of P3 divided by P2 on the blower 44 is less than 1, where P2 is the pressure measured upstream of the blower 44 and P3 is the pressure measured downstream of the blower 44, then the blower is rotating by airflow, which is undesirable in this embodiment. Therefore, the controller 50 is configured in this embodiment to ensure that the pressure difference on the blower 44 is greater than 1.0.

[0082] A mass flow meter 46 is disposed in the air supply line 49, preferably downstream of the blower 44 and the throttle valve 48. The mass flow meter senses the mass flow rate of air flowing to the air lubrication system through the air supply line 49. The mass flow meter 46 generates a signal representing the mass flow rate, and the controller 50 receives this mass flow rate signal. The controller 50 also receives a signal from the air lubrication system 200 indicating the desired mass flow rate for the air lubrication system 200. The controller 50 is configured to compare the desired mass flow rate with the measured (actual) mass flow rate for closed-loop control of the mass flow rate and adjust the position of the throttle valve 48 and the speed of the blower 44 accordingly (explained in detail below).

[0083] The position of the throttle valve 48 is controlled by the controller 50 via an actuator coupled to the throttle valve 48. The cross-sectional area of ​​the opening in the throttle valve 48 is adjustable. The throttle valve 48 has an open position and a maximum closed position. In the open position, the cross-sectional area is at its maximum and the throttling rate applied by the throttle valve 48 is at its minimum and close to zero. In the maximum closed position, the cross-sectional area is at its minimum and the throttling rate applied by the throttle valve 48 is at its maximum. The controller 50 can move the position of the throttle valve 48 between these extreme positions to adjust the throttling volume applied by the throttle valve 48 to the airflow passing through the throttle valve 48.

[0084] When the air lubrication system 200 is running, the blower 44 is always running, and all the air supplied from the engine to the air lubrication system 200 passes through a single air supply line 49 and then through the blower 44.

[0085] When the pressure in the intake system is relatively high, for example when the engine has a relatively high engine load, the pressure P1 in the intake system (sensed by the first sensor 34) is higher than the pressure P3 required at the inlet of the air lubrication system 200. Figure 5a This operation is illustrated. Figure 5a The pressures at various locations in the air supply line 49 are shown. It should be noted that the pressures P1, P2, and P3 in the supply line 49 are slightly simplified because the relatively small pressure drops that occur along the length of the air supply line 49 due to frictional losses are not taken into account.

[0086] In this operating state, it is necessary to reduce the pressure P2 at the air inlet of the blower 44 (sensed by the second pressure sensor 42) to ensure that the pressure P2 at the air outlet of the blower 44 is lower than the pressure P3 at the air outlet of the blower 44 again, that is, to ensure a positive pressure difference on the blower 44 so that the blower 44 delivers a positive pumping action.

[0087] This is achieved by using a controller 50 of a throttle valve 48 that applies a throttling rate, resulting in a lower pressure P2 at the inlet of the blower 44. Preferably, the pressure P2 at the inlet of the blower 44 is a predetermined pressure difference lower than the pressure at the outlet of the blower.

[0088] Therefore, the controller 50 is configured to continuously drive the blower 44 via the motor 41 when the air lubrication system 200 is running and all air supplied from the engine 100 to the air lubrication system 200 passes through the blower 44; and the controller 50 is configured to adjust the position of the throttle valve 48 to reduce the pressure at the air inlet of the blower 44 to a level below the desired pressure, preferably, reducing the pressure at the air inlet of the blower 44 by a predetermined pressure difference.

[0089] The controller 50 is configured to cause the blower 44 to operate at at least the minimum operating speed when the air lubrication system 200 is running.

[0090] Therefore, the controller 50 is configured to adjust the position of the throttle valve 48 to enhance the throttling effect of the throttle valve 48 when the pressure in the air inlet of the blower is higher than or equal to the desired pressure or when the pressure in the air inlet of the blower is higher than the desired pressure minus a predetermined difference.

[0091] The controller 50 is configured to receive a first setpoint signal representing a desired mass flow rate for the air lubrication system 200. Optionally, the controller 50 is configured to receive a second setpoint signal representing a desired pressure for the air lubrication system 200.

[0092] The controller 50 is configured to compare the first setpoint signal with the actual mass flow rate measured by the mass flow meter 46.

[0093] The controller 50 is configured to adjust the position of the throttle valve 48 based on a comparison between the first setpoint signal and the actual mass flow rate; preferably, the controller 50 is configured to adjust the position of the throttle valve 48 based on a comparison between the first setpoint signal and the actual mass flow rate in closed-loop control. Therefore, the controller 50 continuously drives the blower 44 by driving the motor 41 at a speed sufficient to provide the desired mass flow rate.

[0094] The controller 50 is configured to adjust the position of the throttle valve 48 when the pressure ratio P3 / P2 on the blower 44 is less than 1, so as to enhance the throttling effect of the throttle valve 48.

[0095] The controller 50 is configured to adjust the position of the throttle valve 48 to increase the throttling degree when the mass flow rate to the air lubrication system is above the desired mass flow rate and the blower 44 is running at the minimum operating speed.

[0096] The controller 50 is configured to open the throttle valve 48 to the fully open position when the intake pressure is lower than the sum of the desired pressure and the pressure loss along the air supply line 49.

[0097] The controller 50 is configured to increase the speed of the blower 44 when the throttle valve 48 is in the fully open position and the mass flow rate is lower than the desired mass flow rate.

[0098] As the pressure P1 in the intake system increases, the controller 50 will selectively apply an increased throttling flow using the throttle valve 48 to ensure that the pressure P2 at the inlet of the blower 44 is sufficiently low, and vice versa: when the pressure in the intake system decreases, the controller 50 will move the throttle valve 48 toward its fully open position. When the pressure in the intake system has decreased sufficiently, the controller 50 will no longer need to reduce the pressure at the air inlet of the blower 44, and the throttle valve 48 will be in its fully open position.

[0099] Figure 5b This illustrates a situation where the first pressure P1 in the intake system is lower than the desired pressure. Under these operating conditions, since the second pressure P2 at the air inlet of blower 44 will be lower than the pressure downstream of blower 44, no throttling is required using throttle valve 48.

[0100] Therefore, the controller 50 is configured to: move the throttle valve 48 to the open position when the pressure P1 of the scavenging air supplied to the scavenging air receiver 2 is lower than the desired pressure, and move the throttle valve 48 to the throttle position when the pressure P1 of the scavenging air supplied to the scavenging air receiver 2 is higher than the desired pressure.

[0101] The controller 50 is configured to move the throttle valve 48 to the open position when the pressure downstream of the blower 44 is lower than the sum of the desired pressure and the pressure loss along the air supply line 49; and the controller 50 is configured to increase the speed of the blower 44 when the throttle valve 48 is in the open position and the mass flow rate is lower than the desired mass flow rate.

[0102] The controller 50 is configured to adjust the position of the throttle valve 48 to increase the throttling degree when the mass flow rate is higher than the desired mass flow rate and the blower 44 is running at the minimum operating speed.

[0103] The controller 50 is configured to move the throttle valve 48 to its minimum throttling position to obtain the desired mass flow rate before increasing the speed of the blower 44 above the minimum operating speed when the mass flow rate is lower than the desired mass flow rate.

[0104] The controller 50 is configured to increase the operating speed of the blower 44 to obtain the desired mass flow rate when the throttle valve 48 is at its minimum throttle position and the mass flow rate is lower than the desired mass flow rate.

[0105] The controller 50 is configured to reduce the operating speed of the blower 44 when the operating speed of the blower 44 is higher than the minimum operating speed and the throttle valve 48 is in the minimum throttling position of the throttle valve 48 and the mass flow rate is higher than the desired mass flow rate, in order to obtain the desired pressure for air in the supply line 49 downstream of the blower 44.

[0106] In one embodiment, the engine 100 includes only a single lubricating air supply line 49, and the lubricating air supply line 49 includes only a single blower 44.

[0107] In this embodiment, the engine 100 does not include a blower bypass line.

[0108] like Figure 6 As shown, the air lubrication system is part of the marine vessel 210, which houses a large marine engine 100 to reduce drag when the vessel moves through water. The marine vessel includes a hull 202 with a flat bottom 204. The waterline is indicated by line 220. The engine 100 is connected to a propeller 208. The air lubrication system 200 delivers pressurized air to a cavity located in the bottom of the hull 202 facing the bow of the marine vessel 210. The air cavity 201 injects a stream of air bubbles 206 below the hull 202, forming a layer of bubbles along the length of the flat bottom 204 of the hull 202. The pressure required by the air lubrication system 200 will depend on the draft of the marine vessel and is substantially equal to the hydrostatic pressure at the bottom 204 of the hull 202. In this embodiment, the air lubrication system sends a signal indicating the required pressure to a controller 50.

[0109] In this embodiment, the controller 50 is configured to adjust the position of the throttle valve 48 to reduce the mass flow rate when the centrifugal blower 44 is allowed to rotate by air force and the mass flow rate is higher than the desired mass flow rate.

[0110] In addition, the controller 50 is configured to adjust the position of the throttle valve 48 to the open position when the blower 44 is driven by the motor 41.

[0111] The controller 50 is also configured to increase the operating speed of the blower 44 when the throttle valve 49 is in the open position and the mass flow rate is lower than the desired mass flow rate.

[0112] The controller 50 can also be configured to adjust the position of the throttle valve 48 when the blower 44 rotates by air force and the mass flow rate is lower than the expected mass flow rate, so as to enhance the throttling effect of the throttle valve 48.

[0113] The controller 50 can also be configured to adjust the position of the throttle valve 48 to increase the throttling degree when the mass flow rate is higher than the desired mass flow rate and the blower 44 is rotated by air force.

[0114] The controller 50 can be configured to move the throttle valve 48 to its minimum throttling position to obtain the desired mass flow rate before increasing the speed of the blower 44 above the minimum operating speed when the mass flow rate is lower than the desired mass flow rate.

[0115] The controller 50 can also be configured to increase the operating speed of the blower 44 when the throttle valve 48 is in its minimum throttle position and the mass flow rate through the air supply line 49 is lower than the desired mass flow rate, in order to obtain the desired mass flow rate through the supply line 49 downstream of the blower 44.

[0116] In this embodiment, the blower 44 is a centrifugal blower with variable geometry, meaning the diffuser (stator) after the impeller (rotor) can be adjusted to increase the applicable flow range (operating range between surge and blockage) required for the air lubrication operating point. This is advantageous for wind-driven rotation because the flow area of ​​the diffuser can be fully opened, thereby minimizing pressure loss. Furthermore, this centrifugal blower 44 is suitable for wind-driven rotation. Wind-driven rotation means that even when the drive motor 41 is turned off, the airflow passing through the centrifugal blower 44 causes the blower 44 to continue rotating. This phenomenon is sometimes referred to as "free rotation." In this embodiment, the centrifugal blower 44 is preferably provided with an active magnet support.

[0117] When the pressure in the intake system is sufficient and there is no need to increase the blower pressure, the centrifugal blower 44 is driven entirely by the airflow through the air supply line 49, without any increase in motor power.

[0118] This embodiment can be implemented without the throttle valve 48 (which can be replaced by an on / off valve (not shown)).

[0119] In this embodiment, the blower 44 has a minimum operating speed, the throttle valve 48 is movable between a minimum throttle position and a maximum throttle position, in which the throttle valve 48 applies minimum throttle, and in the maximum throttle position, the throttle valve 48 applies maximum throttle, and the controller 50 is configured to: When the pressure in the intake system is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line 49, the centrifugal blower 44 is driven by the motor 41. And when the pressure in the intake system is higher than the sum of the desired pressure and the pressure loss along the air supply line 49, the centrifugal blower 44 is allowed to rotate by air force.

[0120] Preferably, the blower 44 includes variable diffuser blades, and the centrifugal blower 44 is configured to move the centrifugal blower 44 to an open diffuser flow area when the centrifugal blower 44 is allowed to rotate by wind power, thereby minimizing pressure loss.

[0121] In a variation of this embodiment, there is no throttling valve (or at least it is not required), and the position of the diffuser blades is used to adjust the throttling effect on the airflow in the air supply line 49. When the mass flow rate is higher than the desired mass flow rate, the controller 50 moves the diffuser blades to a position where the centrifugal blower 44 applies a greater throttling effect to the air passing through the centrifugal blower, and when the mass flow rate is lower than the desired mass flow rate, the controller 50 moves the diffuser blades to a position where the centrifugal blower 44 applies a smaller throttling effect to the air passing through the centrifugal blower.

[0122] Alternatively, or in conjunction with adjustments to the position of the diffuser blades, the controller 50 is configured to cause the motor 41 to operate as a generator when the centrifugal blower 44 is rotated by airflow, thereby generating a load on the centrifugal blower to increase the pressure difference on the centrifugal blower 44 to obtain the desired mass flow rate.

[0123] Figure 7 Another embodiment of the engine 100 is shown. In this embodiment, the reference numerals for corresponding elements are the same as those in the above embodiment. The engine according to this embodiment is basically the same as the engine in the above embodiment, except that the throttle valve 48 is located downstream of the blower 44, and the operation of the blower 44 and the throttle valve 48 differs due to the different position of the throttle valve 48.

[0124] Figure 8a and Figure 8b The pressure along air supply line 49 is shown under two different operating conditions. The pressure upstream of the blower is P1'. The pressure downstream of the blower 44 and upstream of the throttle valve 48 is P2', and the pressure downstream of the throttle valve is P3'.

[0125] exist Figure 8a Under the operating conditions, the pressure P1' in the engine's intake system is higher than the desired pressure for the air lubrication system 200. Figure 8b Under the operating conditions, the pressure P1' in the engine's intake system is lower than the desired pressure for the air lubrication system 200.

[0126] In this embodiment, the controller 50 is configured to: When the air lubrication system 200 is in operation and all the air supplied from the engine 100 to the air lubrication system 200 passes through the blower 44, the motor 41 continuously drives the blower 44, thereby increasing the air pressure in the air supply line 49. Adjust the position of the throttle valve 48 to obtain the desired mass flow rate.

[0127] The controller 50 is also configured to open the throttle valve 48 to the fully open position when the scavenging pressure is lower than the sum of the desired pressure and the pressure loss along the air supply line.

[0128] The controller is also configured to increase the speed of the blower 44 when the throttle valve 48 is in the fully open position and the mass flow rate is lower than the desired mass flow rate.

[0129] This document describes methods, engines, and marine vessels in conjunction with various embodiments. However, by studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "the" do not exclude multiple. A single controller or other unit can perform the functions of multiple items described in the claims. The fact that certain measures are described in different dependent claims does not in itself indicate that these measures cannot be combined to achieve better results. Reference numerals used in the claims should not be construed as limiting the scope.

[0130] Furthermore, the technical solution of this application can also be constructed in the following manner.

[0131] Item 1. A single-flow, large-scale turbocharged two-stroke internal combustion engine 100 for propelling a marine vessel 210, said engine 100 being configured to supply pressurized scavenging air at a desired mass flow rate and pressure to an air lubrication system 200 of said marine vessel 210, said engine 100 comprising: Multiple cylinders 1, each cylinder 1 having a scavenging port 18 and a discharge valve 4, The intake system introduces scavenging air into the cylinder 1. The intake system includes a scavenging air receiver 2 connected to the cylinder 1 via the scavenging port 18. An exhaust system is provided through which exhaust gases generated in the cylinder are discharged. The exhaust system includes an exhaust gas receiver 3 connected to the cylinder 1 via the exhaust valve 4. At least one turbocharger 5, the at least one turbocharger 5 having an exhaust gas driven turbine 8 operably coupled to a compressor 7, and the turbine 8 being disposed in the exhaust system and the compressor 7 being disposed in the intake system for delivering a pressurized scavenging airflow at scavenging pressure to the scavenging air receiver 2, and Lubricating air supply line 49, which is used to supply pressurized air from the intake system to the air lubrication system 200. Blower 44, which is disposed in the supply line 49 and driven by motor 41, includes an air inlet and an air outlet. Or: (i) a throttle valve 48 disposed in the supply line 49 upstream of the blower 44, and a controller 50 configured to: If the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line 49, the position of the throttle valve 48 is adjusted to reduce the pressure at the air inlet of the blower 44 to a level lower than the sum of the desired pressure and the pressure loss downstream of the blower 44 along the air supply line 49. When the air lubrication system 200 is running, the blower 44 is continuously driven by the motor 41, and all the air supplied by the engine 100 to the air lubrication system 200 passes through the blower 44. Or: (ii) A throttle valve 48 is disposed in the supply line 49 downstream of the blower 44, and the controller 50 is configured to: When the air lubrication system 200 is running, the blower 44 is continuously driven by the motor 41, and all the air supplied by the engine 100 to the air lubrication system 200 passes through the blower 44, thereby increasing the air pressure in the air supply line 49. The position of the throttle valve 48 is adjusted to obtain the desired mass flow rate.

[0132] Item 2. The engine 100 according to Item 1, the engine 100 including (i), wherein the controller 50 is configured to continuously drive the blower 44 via the motor 41 at a speed sufficient to provide the desired mass flow rate.

[0133] Item 3. The engine 100 according to item 1 or 2, wherein the engine 100 includes the (i) wherein the controller 50 is configured to adjust the position of the throttle valve 48 to reduce the pressure at the air inlet of the blower 44 to a level below the desired pressure.

[0134] Item 4. The engine 100 according to any of the preceding items, wherein the engine 100 includes the (i) wherein the controller 50 is configured to receive a setpoint signal representing the desired mass flow rate.

[0135] Item 5. The engine 100 according to any one of the preceding items, the engine 100 comprising (i), wherein the second pressure P2 is measured by a second sensor 42, the second sensor 42 being configured to provide a second signal representing the air pressure P2 at the air inlet of the blower 44, and wherein the controller 50 is configured to receive the signal of the second pressure P2 measured by the second sensor 42 and the signal of a third pressure P3 measured by a third sensor 47, the third sensor 47 being configured to provide a third signal representing the air pressure P3 at the air outlet of the blower 44.

[0136] Item 6. The engine 100 according to any of the preceding items, wherein the engine 100 includes the (i) wherein the controller 50 is configured to cause the blower 44 to operate at at least a minimum operating speed when the air lubrication system 200 is running.

[0137] Item 7. The engine 100 according to Item 6, the engine 100 including (i), wherein the controller 50 is configured to: adjust the position of the throttle valve 48 to increase the throttling degree when the mass flow to the air lubrication system is higher than the desired mass flow and the blower 44 is running at a minimum operating speed.

[0138] Item 8. The engine 100 according to any of the preceding items, wherein the controller 50 is configured to open the throttle valve 48 to the fully open position when the scavenging pressure is lower than the sum of the desired pressure and the pressure loss along the air supply line 49.

[0139] Item 9. The engine 100 according to Item 8, wherein the controller 50 is configured to increase the speed of the blower 44 when the throttle valve 48 is in the fully open position and the mass flow rate is lower than the desired mass flow rate.

[0140] Item 10. The engine 100 according to any of the preceding items, wherein the intake system includes an intercooler 14 located between the compressor 7 and the scavenging air receiver 2, and wherein the inlet of the lubricating air supply line 49 is connected to the intake system at a location downstream of the intercooler 14.

[0141] Item 11. The engine 100 according to any of the preceding items, the engine 100 including only a single lubricating air supply line 49.

[0142] Item 12. The engine 100 according to Item 11, wherein the lubricating air supply line 49 includes only a single blower 44.

[0143] Item 13. The engine 100 according to item 11 or 12, wherein the engine 100 does not include a blower bypass line.

[0144] Item 14. The engine 100 according to any of the preceding items, wherein the lubricating air supply line 49 includes a water mist trap 43 located between the throttle valve 48 and the blower 44.

[0145] Item 15. The engine 100 according to Item 1, the engine 100 comprising (ii), wherein the centrifugal blower 44 has a minimum operating speed, the throttle valve 48 is movable between a minimum throttle position and a maximum throttle position, wherein the throttle valve 48 applies minimum throttle in the minimum throttle position and applies maximum throttle in the maximum throttle position, and the controller 50 is configured to: Move the throttle valve 48 to a position that corresponds to the desired mass flow rate. When the throttle valve 48 applies a greater throttle than at the minimum throttle position, the speed of the blower 44 is reduced towards the minimum operating speed. When the throttle valve 48 is in the minimum throttle position and the mass flow rate is lower than the desired mass flow rate, the speed of the blower 44 is increased.

[0146] Item 16. A marine vessel 210, the marine vessel 210 comprising an air lubrication system 200 and an engine 100 according to any of the preceding items.

[0147] Item 17. A method of operating a single-flow, large-scale turbocharged two-stroke internal combustion engine 100 for propelling a marine vessel 210, said engine 100 being configured to supply pressurized scavenging air at a desired mass flow rate and at a desired pressure to an air lubrication system 200 of said marine vessel 210, said engine 100 comprising: Multiple cylinders 1, each cylinder 1 having a scavenging port 18 and a discharge valve 4, The intake system introduces scavenging air into the cylinder 1. The intake system includes a scavenging air receiver 2 connected to the cylinder 1 via the scavenging port 18. An exhaust system is provided through which exhaust gases generated in the cylinder are discharged. The exhaust system includes an exhaust gas receiver 3 connected to the cylinder 1 via the exhaust valve 4. At least one turbocharger 5, the at least one turbocharger 5 having an exhaust gas driven turbine 8 operably coupled to a compressor 7, and the turbine 8 being disposed in the exhaust system and the compressor 7 being disposed in the intake system for delivering a pressurized scavenging airflow at scavenging pressure to the scavenging air receiver 2. A lubricating air supply line 49 is provided for supplying pressurized air from the intake system to the air lubrication system 200. Blower 44, which is disposed in the supply line 49 and driven by motor 41, includes an air inlet and an air outlet, wherein: Or: (i) a throttle valve 48 disposed in the supply line 49 upstream of the blower 44, and the method comprising: If the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line 49, the position of the throttle valve 48 is adjusted to reduce the pressure at the air inlet of the blower 44 to a level lower than the sum of the desired pressure and the pressure loss downstream of the blower 44 along the air supply line 49. When the air lubrication system 200 is running, the blower 44 is continuously driven by the motor 41, and all the air supplied by the engine 100 to the air lubrication system 200 passes through the blower 44. Or: (ii) A throttle valve 48, which is disposed in the supply line 49 downstream of the blower 44, and When the air lubrication system 200 is running, the blower 44 is continuously driven by the motor 41, and all the air supplied by the engine 100 to the air lubrication system 200 passes through the blower 44, thereby increasing the air pressure in the air supply line 49. The position of the throttle valve 48 is adjusted to obtain the desired mass flow rate.

[0148] Item 18. The method according to Item 17, the method comprising: opening the throttle valve 48 to the fully open position when the scavenging pressure is lower than the sum of the desired pressure and the pressure loss along the air supply line 49.

[0149] Item 19. The method according to Item 18, the method comprising: increasing the speed of the blower 44 when the throttle valve 48 is in the fully open position and the mass flow rate is lower than the desired mass flow rate.

[0150] Item 20. The method according to Item 19, the method comprising (ii), wherein the blower 44 has a minimum operating speed, the throttle valve 48 is movable between a minimum throttle position and a maximum throttle position, wherein in the minimum throttle position the throttle valve 48 applies minimum throttle, and in the maximum throttle position the throttle valve 48 applies maximum throttle, the method comprising: Move the throttle valve 48 to a position that corresponds to the desired mass flow rate. When the throttle valve 48 applies a greater throttle than at the minimum throttle position, the speed of the blower 44 is reduced towards the minimum operating speed. When the throttle valve 48 is in the minimum throttle position and the mass flow rate is lower than the desired mass flow rate, the speed of the blower 44 is increased.

[0151] Item 21. A single-flow, large-scale turbocharged two-stroke internal combustion engine 100 for propelling a marine vessel 210, said engine 100 being configured to supply pressurized scavenging air at a desired mass flow rate and at a desired pressure to an air lubrication system 200 of said marine vessel 210, said engine 100 comprising: Multiple cylinders 1, each cylinder 1 having a scavenging port 18 and a discharge valve 4, The intake system introduces scavenging air into the cylinder 1. The intake system includes a scavenging air receiver 2 connected to the cylinder 1 via the scavenging port 18. An exhaust system is provided through which exhaust gases generated in the cylinder are discharged. The exhaust system includes an exhaust gas receiver 3 connected to the cylinder 1 via the exhaust valve 4. At least one turbocharger 5, the at least one turbocharger 5 having an exhaust gas driven turbine 8 operably coupled to a compressor 7, and the turbine 8 being disposed in the exhaust system and the compressor 7 being disposed in the intake system for delivering a pressurized scavenging airflow at scavenging pressure to the scavenging air receiver 2. A lubricating air supply line 49 is provided for supplying pressurized air from the intake system to the air lubrication system 200. A centrifugal blower 44 is disposed in the supply line 49 and driven by a motor 41. The centrifugal blower 44 includes an air inlet and an air outlet. The controller 50 is configured to: When the scavenging pressure is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line 49, the centrifugal blower 44 is driven by the motor 41. When the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line 49, the centrifugal blower 44 is allowed to rotate by airflow.

[0152] Item 22. The engine 100 according to Item 21, the engine 100 including a throttle valve 48 disposed in the supply line 49 upstream of the blower 44, wherein the controller 50 is configured to adjust the position of the throttle valve 48 to reduce the mass flow rate when the centrifugal blower 44 is allowed to rotate by air force and the mass flow rate is higher than the desired mass flow rate.

[0153] Item 23. The engine 100 according to item 21 or 22, wherein the controller 50 is configured to adjust the position of the throttle valve 48 to the open position when the centrifugal blower 44 is driven by the motor 41.

[0154] Item 24. The engine 100 according to Item 23, wherein the controller 50 is configured to increase the operating speed of the centrifugal blower 44 when the throttle valve 48 is in the open position and the mass flow rate is lower than the desired mass flow rate.

[0155] Item 25. The engine 100 according to any one of items 21 to 24, wherein the centrifugal blower 44 includes variable diffuser blades, and the centrifugal blower 44 is configured to adjust the position of the diffuser blades to obtain the desired mass flow rate when the centrifugal blower 44 is allowed to rotate by wind power.

[0156] Item 26. The engine 100 according to any one of items 21 to 25, wherein the centrifugal blower 44 includes an active magnet support.

[0157] Item 27. The engine 100 according to any one of items 21 to 26, wherein the controller 50 is configured to adjust the position of the throttle valve 48 to enhance the throttling effect of the throttle valve 48 when the centrifugal blower 44 rotates by air force and the mass flow rate is higher than the desired mass flow rate.

[0158] Item 28. The engine 100 according to any one of items 21 to 27, wherein the controller 50 is configured to receive a setpoint signal representing the desired mass flow rate.

[0159] Item 29. An engine 100 according to any one of items 21 to 28, the engine 100 including a first pressure sensor 34 configured to provide a first signal representing the pressure P1 of the scavenging air supplied to the scavenging air receiver 2, wherein a controller 50 is configured to receive the first signal, and wherein, preferably, the controller 50 is configured to move the throttle valve 48 to the open position when the pressure P1 of the scavenging air supplied to the scavenging air receiver 2 is lower than the sum of the desired pressure and the pressure loss along the air supply line 49.

[0160] Item 30. The engine 100 according to any one of items 21 to 29, wherein the controller 50 is configured to adjust the position of the throttle valve 48 to increase the degree of throttling when the mass flow rate is higher than the desired mass flow rate and the centrifugal blower 44 rotates by air force.

[0161] Item 31. The engine 100 according to item 30, wherein the controller 50 is configured to: when the mass flow rate is lower than the desired mass flow rate, move the throttle valve 48 to the minimum throttling position of the throttle valve 48 to obtain the desired mass flow rate before increasing the speed of the blower 44 above the minimum operating speed.

[0162] Item 32. The engine 100 according to Item 31, wherein the controller 50 is configured to increase the operating speed of the centrifugal blower 44 to obtain the mass flow rate when the throttle valve 48 is at its minimum throttling position and the mass flow rate is lower than the desired mass flow rate.

[0163] Item 33. The engine 100 according to any one of items 21 to 32, wherein the intake system includes an intercooler 14 between the compressor 7 and the scavenging air receiver 2, and wherein the inlet of the lubricating air supply line 49 is connected to the intake system at a location downstream of the intercooler 14.

[0164] Item 34. The engine 100 according to any one of items 21 to 33, wherein the engine 100 includes only a single lubricating air supply line 49.

[0165] Item 35. The engine 200 according to Item 34, wherein the lubricating air supply line 49 includes only a single centrifugal blower 44.

[0166] Item 36. The engine according to Item 33 or 35, wherein the engine 100 does not include a blower bypass line.

[0167] Item 37. The engine 100 according to any one of items 21 to 36, wherein the controller 50 is configured to shut off the motor 41 when the centrifugal blower 44 is allowed to rotate by air force.

[0168] Item 38. The engine 100 according to Item 21, wherein the controller 50 is configured to: when the centrifugal blower 44 rotates by wind power, cause the motor 41 to operate as a generator, thereby generating a load on the centrifugal blower to increase the pressure difference on the centrifugal blower 44, thereby obtaining the desired mass flow rate.

[0169] Item 39. A marine vessel 210, the marine vessel 210 comprising an air lubrication system 200 and an engine 100 according to any one of items 21 to 38.

[0170] Item 40. A method of operating a single-flow, large-scale turbocharged two-stroke internal combustion engine 100 for propelling a marine vessel 210, said engine 100 being configured to supply pressurized scavenging air at a desired mass flow rate and at a desired pressure to an air lubrication system 200 of said marine vessel 210, said engine 100 comprising: Multiple cylinders 1, each cylinder 1 having a scavenging port 18 and a discharge valve 4, The intake system introduces scavenging air into the cylinder 1. The intake system includes a scavenging air receiver 2 connected to the cylinder 1 via the scavenging port 18. An exhaust system is provided through which exhaust gases generated in the cylinder are discharged. The exhaust system includes an exhaust gas receiver 3 connected to the cylinder 1 via the exhaust valve 4. At least one turbocharger 5, the at least one turbocharger 5 having an exhaust gas driven turbine 8 operably coupled to a compressor 7, and the turbine 8 being disposed in the exhaust system and the compressor 7 being disposed in the intake system for delivering a pressurized scavenging airflow at scavenging pressure to the scavenging air receiver 2. A lubricating air supply line 49 is provided for supplying pressurized air from the intake system to the air lubrication system 200. Blower 44, which is disposed in the supply line 49 and driven by motor 41, includes an air inlet and an air outlet. The method includes: When the scavenging pressure is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line 49, the centrifugal blower 44 is driven by the motor 41. When the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line 49, the centrifugal blower 44 is allowed to rotate by airflow.

[0171] Item 41. The method according to Item 40, the method comprising a throttle valve 48 disposed in the supply line 49 upstream of the blower 44, and the method comprising: adjusting the position of the throttle valve 48 to reduce the mass flow rate when the centrifugal blower 44 is rotating by air force and the mass flow rate is higher than the desired pressure.

[0172] Item 42. The method according to Item 41, the method comprising: adjusting the position of the throttle valve 48 to the open position when the centrifugal blower 44 is driven by the motor 41.

[0173] Item 43. The method according to Item 42, the method comprising: increasing the operating speed of the centrifugal blower 44 when the throttle valve 48 is in the open position and the mass flow rate is lower than the desired pressure.

[0174] Item 44. The method according to Item 40, the method comprising: when the centrifugal blower 44 rotates by wind power, causing the motor 41 to operate as a generator, thereby generating a load on the centrifugal blower to increase the pressure difference on the centrifugal blower, thereby obtaining the desired mass flow rate.

Claims

1. A single-flow, large-scale turbocharged two-stroke internal combustion engine (100) for propelling a marine vessel (210), said engine (100) being configured to supply pressurized scavenging air at a desired mass flow rate and at a desired pressure to an air lubrication system (200) of said marine vessel (210), said engine (100) comprising: Multiple cylinders (1), each cylinder (1) having a scavenging port (18) and a discharge valve (4). The intake system is used to introduce scavenging air into the cylinder (1). The intake system includes a scavenging air receiver (2) connected to the cylinder (1) via the scavenging port (18). The exhaust system, through which exhaust gases generated in the cylinder are discharged, includes an exhaust gas receiver (3) connected to the cylinder (1) via the exhaust valve (4). At least one turbocharger (5), the at least one turbocharger (5) having an exhaust gas driven turbine (8) operably coupled to a compressor (7), and the turbine (8) being disposed in the exhaust system and the compressor (7) being disposed in the intake system for delivering a pressurized scavenging airflow at scavenging pressure to the scavenging air receiver (2), and Lubricating air supply line (49) is used to supply pressurized air from the intake system to the air lubrication system (200). A blower (44), said blower (44) being disposed in said supply line (49) and driven by a motor (41), said blower (44) including an air inlet and an air outlet, characterized in that, Or: (i) a throttle valve (48) disposed in the supply line (49) upstream of the blower (44), and a controller (50) configured to: If the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line (49), the position of the throttle valve (48) is adjusted to reduce the pressure at the air inlet of the blower (44) to a level lower than the sum of the desired pressure and the pressure loss along the air supply line (49) downstream of the blower (44), and When the air lubrication system (200) is running, the blower (44) is continuously driven by the motor (41), and all the air supplied by the engine (100) to the air lubrication system (200) passes through the blower (44). Or: (ii) A throttle valve (48) is disposed in the supply line (49) downstream of the blower (44), and a controller (50) is configured to: When the air lubrication system (200) is running, the blower (44) is continuously driven by the motor (41), and all the air supplied by the engine (100) to the air lubrication system (200) passes through the blower (44), thereby increasing the air pressure in the air supply line (49), and The position of the throttle valve (48) is adjusted to obtain the desired mass flow rate.

2. The engine (100) according to claim 1, wherein the engine (100) comprises the (i) wherein, The controller (50) is configured to continuously drive the blower (44) via the motor (41) at a speed sufficient to provide the desired mass flow rate.

3. The engine (100) according to claim 1 or 2, wherein the engine (100) comprises (i), The controller (50) is configured to adjust the position of the throttle valve (48) to reduce the pressure at the air inlet of the blower (44) to a level below the desired pressure.

4. The engine (100) according to any one of the preceding claims, wherein the engine (100) comprises (i), The controller (50) is configured to receive a setpoint signal representing the desired mass flow rate.

5. The engine (100) according to any one of the preceding claims, the engine (100) comprising (i), and wherein, The second pressure (P2) is measured by a second sensor (42), which is configured to provide a second signal representing the air pressure (P2) at the air inlet of the blower (44), and wherein the controller (50) is configured to receive the signal of the second pressure (P2) measured by the second sensor (42) and the signal of the third pressure (P3) measured by a third sensor (47), which is configured to provide a third signal representing the air pressure (P3) at the air outlet of the blower (44).

6. A marine vessel (210) comprising an air lubrication system (200) and an engine (100) according to any one of the preceding claims.

7. A method of operating a single-flow, large-scale turbocharged two-stroke internal combustion engine (100) for propelling a marine vessel (210), said engine (100) being configured to supply pressurized scavenging air at a desired mass flow rate and at a desired pressure to an air lubrication system (200) of said marine vessel (210), said engine (100) comprising: Multiple cylinders (1), each cylinder (1) having a scavenging port (18) and a discharge valve (4). The intake system is used to introduce scavenging air into the cylinder (1). The intake system includes a scavenging air receiver (2) connected to the cylinder (1) via the scavenging port (18). The exhaust system, through which exhaust gases generated in the cylinder are discharged, includes an exhaust gas receiver (3) connected to the cylinder (1) via the exhaust valve (4). At least one turbocharger (5), the at least one turbocharger (5) having an exhaust gas driven turbine (8) operably coupled to a compressor (7), and the turbine (8) being disposed in the exhaust system and the compressor (7) being disposed in the intake system for delivering a pressurized scavenging air flow at scavenging pressure to the scavenging air receiver (2). A lubricating air supply line (49) is provided for supplying pressurized air from the intake system to the air lubrication system (200), and A blower (44), which is disposed in the supply line (49) and driven by a motor (41), the blower (44) includes an air inlet and an air outlet, characterized in that: Or: (i) a throttle valve (48) disposed in the supply line (49) upstream of the blower (44), and the method comprising: If the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line (49), the position of the throttle valve (48) is adjusted to reduce the pressure at the air inlet of the blower (44) to a level lower than the sum of the desired pressure and the pressure loss along the air supply line (49) downstream of the blower (44), and When the air lubrication system (200) is running, the blower (44) is continuously driven by the motor (41), and all the air supplied by the engine (100) to the air lubrication system (200) passes through the blower (44). Or: (ii) A throttle valve (48) disposed in the supply line (49) downstream of the blower (44), and When the air lubrication system (200) is running, the blower (44) is continuously driven by the motor (41), and all the air supplied by the engine (100) to the air lubrication system (200) passes through the blower (44), thereby increasing the air pressure in the air supply line (49), and The position of the throttle valve (48) is adjusted to obtain the desired mass flow rate.

8. A single-flow, large-scale turbocharged two-stroke internal combustion engine (100) for propelling a marine vessel (210), said engine (100) being configured to supply pressurized scavenging air at a desired mass flow rate and at a desired pressure to an air lubrication system (200) of said marine vessel (210), said engine (100) comprising: Multiple cylinders (1), each cylinder (1) having a scavenging port (18) and a discharge valve (4). The intake system is used to introduce scavenging air into the cylinder (1). The intake system includes a scavenging air receiver (2) connected to the cylinder (1) via the scavenging port (18). The exhaust system, through which exhaust gases generated in the cylinder are discharged, includes an exhaust gas receiver (3) connected to the cylinder (1) via the exhaust valve (4). At least one turbocharger (5), the at least one turbocharger (5) having an exhaust gas driven turbine (8) operably coupled to a compressor (7), and the turbine (8) being disposed in the exhaust system and the compressor (7) being disposed in the intake system for delivering a pressurized scavenging air flow at scavenging pressure to the scavenging air receiver (2). A lubricating air supply line (49) is provided for supplying pressurized air from the intake system to the air lubrication system (200), and A centrifugal blower (44), which is disposed in the supply line (49) and driven by a motor (41), the centrifugal blower (44) including an air inlet and an air outlet, characterized in that a controller (50) is configured to: When the scavenging pressure is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line (49), the centrifugal blower (44) is driven by the motor (41), and When the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line (49), the centrifugal blower (44) is allowed to rotate by air force.

9. A marine vessel (210) comprising an air lubrication system (200) and an engine (100) according to claim 8.

10. A method of operating a single-flow, large-scale turbocharged two-stroke internal combustion engine (100) for propelling a marine vessel (210), said engine (100) being configured to supply pressurized scavenging air at a desired mass flow rate at a desired pressure to an air lubrication system (200) of said marine vessel (210), said engine (100) comprising: Multiple cylinders (1), each cylinder (1) having a scavenging port (18) and a discharge valve (4). The intake system is used to introduce scavenging air into the cylinder (1). The intake system includes a scavenging air receiver (2) connected to the cylinder (1) via the scavenging port (18). The exhaust system, through which exhaust gases generated in the cylinder are discharged, includes an exhaust gas receiver (3) connected to the cylinder (1) via the exhaust valve (4). At least one turbocharger (5), the at least one turbocharger (5) having an exhaust gas driven turbine (8) operably coupled to a compressor (7), and the turbine (8) being disposed in the exhaust system and the compressor (7) being disposed in the intake system for delivering a pressurized scavenging air flow at scavenging pressure to the scavenging air receiver (2). A lubricating air supply line (49) is provided for supplying pressurized air from the intake system to the air lubrication system (200), and A blower (44), said blower (44) being disposed in said supply line (49) and driven by a motor (41), said blower (44) including an air inlet and an air outlet, characterized in that, The method includes: When the scavenging pressure is equal to or lower than the sum of the desired pressure and the pressure loss along the air supply line (49), the centrifugal blower (44) is driven by the motor (41). When the scavenging pressure is higher than the sum of the desired pressure and the pressure loss along the air supply line (49), the centrifugal blower (44) is allowed to rotate by air force.

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