JP2010241160A - Ship propulsion system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent any load fluctuation from being transmitted to an internal combustion engine when short-term disturbance such as waves and swells are applied to a propeller of ship. <P>SOLUTION: A motor generator 14 is provided on a power transmission path 12 for connecting a propeller 11 to a main shaft of an internal combustion engine 13. When the load torque applied to the propeller 11 is less than the output torque of the internal combustion engine 13, the power is supplied to a power-supplied part such as an electric apparatus 17 by the motor generator 14. When the load torque is more than the output torque, the power is supplied from a power source to the motor generator 14 to operate the motor generator 14 and to assist the power to the propeller 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a marine vessel propulsion device that prevents load fluctuations from being applied to an internal combustion engine due to disturbances such as waves on the water surface during vessel navigation.

  An internal combustion engine is usually used as a power source for ships that sail on the water by propeller thrust, and hybrid propulsion devices that have an electric motor as a power source in addition to the internal combustion engine are described in Patent Documents 1 and 2. Has been. This hybrid propulsion device has a generator that is driven by an internal combustion engine to generate electric power, and the battery is charged with electric power by driving the generator while driving the propeller by the internal combustion engine during navigation of the ship, and the electric motor is driven. Power is supplied from the battery to the electric motor. In order to reduce the size of the propulsion device, a motor generator having an electric motor function and a generator function is used.

  In a conventional hybrid type propulsion device, a propeller is driven by an internal combustion engine during steady navigation of a ship, and a propeller is driven by an electric motor during low-speed or very low-speed navigation and backward navigation that is less frequently used. The propeller is driven by an electric motor during slow speed travel or reverse travel to eliminate the noise of the internal combustion engine, and to supply electric power from the battery to the electrical equipment when the ship is stopped and moored.

  As described above, in order to drive the propeller by the electric motor at the time of slow speed travel or reverse travel, the generator is driven by the internal combustion engine during normal travel and the battery is charged in advance.

JP 2001-270495 A Japanese Patent Laid-Open No. 2001-301692

  When navigating the ship, disturbances such as tidal currents, wind pressures, waves and swells are applied to the hull, and the load applied to the propeller is increased or decreased by the disturbances. If the load applied to the propeller fluctuates frequently, the number of revolutions of the internal combustion engine changes frequently and fuel consumption is deteriorated. When the load applied to the propeller increases due to disturbance, the electric motor is driven to assist the drive of the propeller, and when the load decreases, the generator is driven to generate power, thereby preventing fluctuations in the load applied to the internal combustion engine. It is possible to improve the fuel efficiency of the internal combustion engine. In view of this, the present inventor has studied the system for controlling the operation of the motor generator in accordance with the load fluctuation applied to the propeller as follows.

  When a ship such as a cargo ship or a merchant ship sails in the open ocean, the speed of the internal combustion engine is set so that the speed of the propeller is constant. Since the rotation speed of the propeller needs to be different depending on the navigation resistance of the ship, the rotation speed of the main shaft of the internal combustion engine is set by adjusting the fuel supplied to the internal combustion engine according to the navigation resistance. Further, even if the main shaft of the internal combustion engine has the same rotational speed, the amount of propeller slip varies depending on the sea condition, so that the operating device is operated by the occupant so that the ship reaches the target ship speed, and the internal combustion engine is operated according to the sea condition. The rotation speed is set.

  A marine vessel propulsion apparatus is provided with a speed governor, that is, a governor. The governor constantly detects the rotational speed of the internal combustion engine, calculates a deviation from the set rotational speed, and adjusts the fuel supply amount so as to be the set rotational speed. The governor's control frequency is about 20 Hz, but the time lag from the adjustment of the fuel supply amount to the change of the rotation speed of the propeller is from several seconds to several tens of seconds. This is because a marine internal combustion engine has not only its own weight but also the mass of a flywheel and a propeller connected to the main shaft, so that these inertial forces are large. Therefore, there is a large time lag as described above from the start of fuel supply adjustment until the rotational speed changes.

  Among the disturbances applied to the ship, the tidal current and wind pressure are medium- to long-term disturbances that change with a period of several hours, and among the disturbances, waves and swells are short-term disturbances that change with a period of several seconds to several tens of seconds. ing.

  For this reason, when the spindle speed changes due to a short-term disturbance, the governor cannot stably control the spindle speed in response to the disturbance even though the governor control frequency is high. . This is because the governor monitors the rotational speed with a time lag, and when the sign of the rotational speed change is seen, the load torque may have already changed, and the load torque may already be in a different state. Because. In addition, there is a time lag of several seconds to several tens of seconds until the governor adjusts the fuel supply amount after detecting the change in the rotation speed and the effect occurs, so that the influence will affect the input signal of the next control It becomes. Therefore, it is difficult to adjust the fuel for short-term disturbances that change from moment to moment according to the characteristics of the governor. As described above, the governor contributes to the control of the spindle speed for medium- to long-term disturbances, but is considered to be an unstable factor in controlling the spindle speed for short-term disturbances. In the actual ship measurement results, the energy-saving effect is recognized by reducing the governor control frequency.

  In this way, for medium- to long-term disturbances, the governor can adjust the fuel supply amount to the internal combustion engine and control the output torque of the internal combustion engine against the load fluctuation of the propeller. When a disturbance is applied, the load applied to the internal combustion engine cannot be suppressed depending on the governor.

  An object of the present invention is to prevent load fluctuations from being transmitted to an internal combustion engine when a short-term disturbance such as a wave or swell is applied to a propeller of a ship.

  Another object of the present invention is to improve the fuel consumption of an internal combustion engine by preventing load fluctuations from being applied to the internal combustion engine.

  A marine vessel propulsion device according to the present invention is a marine vessel propulsion device having a power transmission path that connects a propeller that applies thrust to the marine vessel and a main shaft of an internal combustion engine, and is provided in the power transmission path and driven by the internal combustion engine Generated to generate electric power, an electric power supplied portion to which electric power generated by the generator is supplied, load torque detecting means for detecting load torque applied to the propeller, and detected by the load torque detecting means A control means for comparing a load torque with an output torque of the internal combustion engine, and when the load torque is less than the output torque, operating the generator by the internal combustion engine to supply electric power to the power supplied portion; It is characterized by having.

  A marine vessel propulsion device according to the present invention is a marine vessel propulsion device having a power transmission path that connects a propeller that applies thrust to the marine vessel and a main shaft of an internal combustion engine, and is provided in the power transmission path, and provides power to the propeller. An electric motor to be applied; an electric power source that supplies electric power to the electric motor; load torque detection means that detects load torque applied to the propeller; load torque detected by the load torque detection means; and output torque of the internal combustion engine And control means for assisting power to the propeller by operating the electric motor with the power from the power source when the load torque exceeds the output torque.

  A marine vessel propulsion device according to the present invention is a marine vessel propulsion device having a power transmission path that connects a propeller that applies thrust to the marine vessel and a main shaft of an internal combustion engine, and is provided in the power transmission path and driven by the internal combustion engine A motor generator that generates power while supplying power to the propeller, a power supplied unit that is supplied with power generated by the motor generator, a power source that supplies power to the motor generator, and the propeller Load torque detecting means for detecting a load torque applied to the load torque, and comparing the load torque detected by the load torque detecting means with the output torque of the internal combustion engine, and when the load torque is lower than the output torque, the motor A generator is operated by the internal combustion engine to supply power to the power supplied portion, and the load torque is When it exceeds the serial output torque is characterized by having a control means for assisting the motive power to the propeller by running the motor generator with electric power from the power source. In the marine vessel propulsion device according to the present invention, the power supplied unit and the power source are batteries, and when the load torque is lower than the output torque, the battery is charged with power generated by the motor generator, and the load When the torque exceeds the output torque, the motor generator is operated by the power of the battery to assist the propeller with power.

  According to the present invention, when a short-term disturbance such as a wave or swell generated on the water surface is applied to the ship and the load torque applied to the propeller during the navigation of the ship is lower than the output torque of the internal combustion engine, the generator is operated. As a result, when the load torque applied to the propeller is reduced, power is generated using the output torque of the internal combustion engine, so that load fluctuations can be prevented from being transmitted to the internal combustion engine. On the other hand, when the load torque applied to the propeller exceeds the output torque of the internal combustion engine, the electric motor is operated to assist the propeller with power, so that it is possible to prevent load fluctuation from being transmitted to the internal combustion engine. it can. Since transmission of load fluctuations to the internal combustion engine is prevented, the rotational speed of the internal combustion engine can always be kept constant even when a disturbance is applied to the ship, and the fuel consumption of the internal combustion engine can be improved.

  By charging the battery with the power generated by the generator and supplying the power from the battery when operating the electric motor, the power generated by waves on the water surface can be assisted to the propeller power. Compared with the case where the output torque of the internal combustion engine is changed in response to the fluctuation of the engine, the fuel consumption of the internal combustion engine can be improved.

  By disposing the motor generator having the functions of the electric motor and the generator in the power transmission path, the propulsion device can be made smaller than when the electric motor and the generator are separately provided.

It is a block diagram which shows the propulsion apparatus of the ship which is one embodiment of this invention. It is a schematic diagram which shows the state which the ship is navigating the water surface which the wave has generate | occur | produced. (A) is a schematic diagram showing a state in which the water surface is changed with respect to the standard water level due to the generation of waves, (B) is a schematic diagram showing changes in ship speed due to the waves, (C) is a diagram showing the change in the waves It is a schematic diagram which shows the change of the load torque added to a propeller, (D) is a schematic diagram which shows the rotation speed of an internal combustion engine in case the load torque fluctuates by a wave compared with a prior art. It is a time chart which shows the control mode of the propulsion apparatus at the time of ship navigation. FIG. 6 is a characteristic diagram showing the relationship between the engine output torque and the rotational speed of the main shaft under a condition where the fuel supply amount to the engine is constant. It is a block diagram which shows the propulsion apparatus which is other embodiment of this invention. It is a block diagram which shows the propulsion apparatus which is further another embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a propeller shaft 12 a provided with a propeller 11 that applies thrust to a ship is connected to a main shaft 12 b of an engine, that is, an internal combustion engine 13. The propeller shaft 12 a and the main shaft 12 b constitute a power transmission path 12, and the net output of the engine, that is, the output torque is transmitted to the propeller 11 via the power transmission path 12. A motor generator 14 is provided in the power transmission path 12, and the motor generator 14 has a function as an electric motor that applies power to the propeller 11 and a function as a generator that generates power by being driven by the internal combustion engine 13. is doing.

  In order for the occupant to set the engine speed, the operation device 15 is provided with an operation handle 15a, and an engine speed command signal input by the occupant operating the operation handle 15a is sent to the governor 16. It is like that. The governor 16 sends a fuel supply amount command signal to the internal combustion engine 13 so that the main shaft 12b of the internal combustion engine 13 has a rotational speed corresponding to the command signal. From the internal combustion engine 13, the actual rotational speed signal of the main shaft 12b and the actual fuel supply amount signal are sent to the governor 16, and the internal combustion engine 13 is feedback-controlled so that the main shaft 12b has the set rotational speed.

  In order to satisfy the power demand of various electrical devices 17 provided in the ship, a generator 18 is provided in the ship, and the electric power generated by the generator 18 is supplied to the electrical device 17 via the inboard bus 19. Sent to. The electric device 17 in the ship is a power supplied unit that functions when supplied with power, and the generator 18 is a power source that supplies power to the power supplied unit.

  The motor generator 14 is connected to the inboard bus 19 via an inverter 21. Thereby, the electric power generated by operating the motor generator 14 as a generator can be supplied to the electric power demand of the electric device 17 through the inverter 21. On the other hand, when the motor generator 14 is operated as an electric motor to assist the propeller 11 with power, electric power can be supplied to the motor generator 14 from the generator 18. Further, a secondary battery, that is, a battery 22 is mounted in the ship, and the electric power of the battery 22 can be supplied to the motor generator 14 to operate the motor generator 14 as an electric motor. The charged electric power can be charged in the battery 22. Thus, by providing the battery 22 in the propulsion device, the battery 22 constitutes a power source and a power supplied portion.

  The propulsion device shown in FIG. 1 can supply electric power to the motor generator 14 from either the generator 18 or the battery 22, and the electric power generated by the motor generator 14 can be supplied to either the electric device 17 or the battery 22 in the ship. It is a form that can also be supplied. As a form of the propulsion device, an electric power can be supplied to the motor generator 14 from either the generator 18 or the battery 22, and the electric power generated by the motor generator 14 can be supplied to either the electric device 17 or the battery 22 in the ship. There is a form that can be supplied.

  As another form of the propulsion device, there are a form in which electric power is supplied to the motor generator 14 only from the generator 18 and a form in which electric power is supplied to the motor generator 14 only from the battery 22. Similarly, there are a mode in which the electric power generated by the motor generator 14 is supplied only to the electric device 17 in the ship and a mode in which only the battery 22 is supplied.

  In order to detect the load torque applied to the propeller 11 during navigation of the ship, the propeller shaft 12a is provided with a strain gauge 23, and a detection signal is transmitted from the strain gauge 23 to the load torque detector 24 by a radio signal. It has become so. The strain gauge 23 transmits a detection signal corresponding to the torsional stress applied to the propeller shaft 12a to the load torque detector 24 at a cycle of, for example, 500 Hz. Under the state in which the propeller 11 is rotating at a substantially constant rotation speed, when a disturbance such as a wave on the water surface or undulation is applied to the propeller 11 and the load torque varies, the torsional stress of the propeller shaft 12a changes. A load torque applied to the propeller 11 can be detected by a signal from the strain gauge 23. However, in order to detect the load torque, an optical shaft torque meter may be used instead of the strain gauge 23.

  The governor 16 sends a rotational speed signal corresponding to the actual rotational speed of the main shaft 12b and a supply amount signal corresponding to the fuel supply amount actually supplied to the internal combustion engine 13 to the controller 25 as control means. It is supposed to be. Based on these signals sent from the governor 16 to the controller 25, the controller 25 calculates the net output torque of the internal combustion engine 13. Therefore, the controller 25 has a function of calculating the output torque of the internal combustion engine 13, but an output torque signal may be sent to the controller 25 from an engine controller (not shown) that controls the internal combustion engine 13. The net output torque is torque that is output from the main shaft 12b of the internal combustion engine 13 by subtracting friction loss in the cylinder, and is also called braking torque. As a calculation method of the output torque of the internal combustion engine 13, the output torque of the main shaft 12b may be obtained by a shaft torque meter.

  A detection signal from the load torque detector 24 is sent to the controller 25, and the controller 25 compares the output torque of the internal combustion engine 13 with the load torque applied to the propeller shaft 12a. Based on the comparison result, an assist mode in which the motor generator 14 is operated as an electric motor to assist the propeller 11 and power is generated, and a generation mode in which the motor generator is operated as a generator and is supplied to a power supply unit such as the electric device 17. And can be switched.

  FIG. 2 is a schematic diagram showing a state where a ship is navigating the water surface where waves are generated. As shown in FIG. 2, assuming that the ship is navigating in the direction indicated by the arrow on the water surface, the ship is in a state S2 in which the wave goes up from a state S1 in which the wave goes up, and a state S3 in which the wave goes down Then, the wave reaches the lowest point state S4. When a ship navigates under a state where periodic waves are generated, such a navigation state is periodically repeated.

  3A is a schematic diagram showing a state in which the water surface is changing with respect to the standard water level due to the generation of waves, and FIG. 3B is a schematic diagram showing changes in ship speed due to the waves. FIG. 3C is a schematic diagram showing a change in load torque applied to the propeller 11 by the wave, and FIG. 3D is a schematic diagram showing the rotational speed of the internal combustion engine when the load torque fluctuates due to the wave as compared with the conventional one. It is.

  When the ship is in a state S1 where the ship reaches the wave and rises, the navigation resistance applied to the hull increases and the ship speed decreases. Since the inflow speed of the water flowing toward the propeller 11 is also decreased due to the decrease in the ship speed, the load torque applied to the propeller shaft 12a via the propeller 11 is increased. The load torque becomes maximum in the vicinity of the state S2 in which the ship navigates the peak of the wave where the boat speed is the lowest. On the other hand, after passing the top of the wave, the navigation resistance caused by the wave decreases at a stretch, the gravitational acceleration is also added, the ship speed increases rapidly, and the load torque decreases. Therefore, when a wave is generated on the water surface while the ship is navigating, the ship speed and the load torque change as shown in FIGS. 3 (B) and 3 (C). However, changes in ship speed and load torque are schematically shown in FIGS. 3B and 3C, and the phases of ship speed and load torque with respect to actual wave changes are shown in the figure. More complicated phase difference.

  FIG. 4 is a time chart showing the control mode of the propulsion device when navigating the ship. When a constant amount of fuel is supplied to the internal combustion engine 13, the target output torque of the main shaft 12b becomes constant. As shown in FIG. 2, when the ship navigates the water surface where waves are generated, the load torque applied to the propeller 11 when the ship sails from the state S1 where the waves rise in FIG. 2 to the peak state S2 of the waves. Increases from the target output torque of the internal combustion engine 13. When an increase in load torque is detected by the load torque detector 24, the signal is sent to the controller 25, and the propulsion device is set to the assist mode. In this assist mode, the motor generator 14 is operated as an electric motor to assist the propeller 11 with power. The assist amount is set to a value corresponding to the load torque. The assisted motor torque is indicated by hatching in FIG.

  On the other hand, in FIG. 2, when the ship sails from the wave peak state S2 to the wave bottom point state S4 through the wave descending state S3, the load torque applied to the propeller 11 is smaller than the target output torque. Will do. When a decrease in load torque is detected by the load torque detector 24, the signal is sent to the controller 25, and the propulsion device is set to the generating mode. In the generating mode, the motor generator is operated as a generator to generate power. The generated power is supplied to an electric power supply unit including the electric device 17 and the battery 22. The power generation amount is set to a value corresponding to the reduced load torque. The torque applied to the motor generator 14 by the internal combustion engine 13 for power generation is shown with dots in FIG.

  Accordingly, when the ship sails on the surface of the water where disturbances such as waves and swells that fluctuate in a short-term cycle occur, if the load torque applied to the propeller 11 increases above the target output torque, the propeller is driven by the motor generator 14. Since the driving torque is assisted by the shaft 12a, the ship can be navigated without increasing the fuel supplied to the internal combustion engine 13, that is, without increasing the target output torque of the internal combustion engine 13. On the other hand, when the load torque applied to the propeller 11 decreases below the target output torque, the motor generator 14 is driven by the internal combustion engine 13 and the output torque of the internal combustion engine 13 is used as power generation energy. The marine vessel can be navigated without decreasing the target fuel and reducing the target output torque of the internal combustion engine 13. In this way, even on the water surface where waves and undulations are generated, a constant amount of fuel is supplied to the internal combustion engine 13, and the rotational speed of the internal combustion engine 13 is changed as shown in FIG. Therefore, the ship can be navigated while maintaining the output torque of the internal combustion engine constant. That is, navigation with a constant output horsepower is possible. In this way, even if load torque is periodically applied, the output torque of the internal combustion engine 13 can be kept constant, so that it is compared with a case where the rotational speed of the internal combustion engine 13 is changed periodically. Can improve fuel efficiency.

  FIG. 5 is a characteristic diagram showing the relationship between the output torque of the internal combustion engine 13 and the rotational speed of the main shaft 12b under the condition that the fuel supply amount to the internal combustion engine 13 is constant. This characteristic diagram shows the characteristics of a diesel engine used as the internal combustion engine 13. In the internal combustion engine 13, the relationship between the output torque and the rotational speed is as shown in FIG. It has characteristics. In FIG. 5, reference signs “a” to “e” indicate fuel supply amounts, respectively, and the fuel supply amount decreases from the reference sign “a” to the reference sign “e”. The diesel engine has an output characteristic that the output torque increases as the rotational speed increases, and the output torque decreases to the right when the rotational speed becomes higher than a predetermined rotational speed P that is the maximum output torque, that is, the maximum horsepower. . At the time of steady navigation of the ship, the main shaft 12b is driven in a region where the rotational speed is lowering to the right.

  For example, when the ship is navigating in the state of point A in FIG. 5, conventionally, if the load torque applied to the propeller 11 increases due to waves and undulations, the rotational speed of the main shaft 12 b decreases, so the governor The fuel supply amount is increased by 16, and the output torque is increased to meet the increase in load torque. On the other hand, when the load torque decreases, the rotational speed increases, so the fuel supply amount is decreased by the governor 16 and the output torque is decreased to meet the decrease in the load torque.

  Therefore, if the fuel supply amount is controlled by the governor 16 for short-term disturbance as in the prior art, the engine speed changes frequently as shown in FIG. Will worsen. Moreover, when the fuel supply amount is controlled by the governor 16, there is a time lag T as shown in FIG. 3D until the control is completed. Therefore, the rotational speed of the main shaft 12b can be stably accommodated to short-term disturbances. Can not control. On the other hand, in the present invention, the rotational speed of the spindle 12b is maintained constant as shown in FIG. 3 (D) by operating the motor generator 14 against a short-term disturbance even under the disturbance. can do.

  As shown in FIG. 1, a motor generator 14 having an electric motor function and a generator function is provided in the power transmission path 12, but the electric motor and the generator may be provided in the power transmission path, respectively. . If only the electric motor is provided in the power transmission path 12, when the load torque increases, the motor power is assisted by the propeller shaft 12a, and the rotation speed of the main shaft 12b is prevented from decreasing when the load torque increases. can do. On the other hand, if only the generator is provided in the power transmission path 12, when the load torque decreases, the generator can generate power. However, as shown in FIG. 1, when the motor generator 14 is arranged in the power transmission path 12, the propulsion device can be reduced in size.

  FIG. 6 is a block diagram showing a marine vessel propulsion apparatus according to another embodiment of the present invention. This propulsion device is a uniaxial type in which the power transmission path 12 of the propulsion apparatus shown in FIG. 1 is in a line, but is a gear box type in which a gear box 26 is provided in the power transmission path 12. The main shaft 12 b of the internal combustion engine 13 is connected to the propeller shaft 12 a via a gear box 26, and the main shaft 14 a of the motor generator 14 is also connected to the propeller shaft 12 a via the gear box 26. In this case, by incorporating a reverse rotation mechanism in the gear box 26, the rotation of the main shaft 12b of the internal combustion engine 13 and the main shaft 14a of the motor generator 14 can be reversed and transmitted to the propeller shaft 12a.

  FIG. 7 is a block diagram showing a marine vessel propulsion apparatus according to still another embodiment of the present invention. In this propulsion device, a waste heat recovery device 31 is provided as a power supply source in addition to the generator 18 in the propulsion device shown in FIG. The waste heat recovery device 31 has a function of generating electric power by using the energy of the exhaust gas discharged from the internal combustion engine 13, and the exhaust gas that has been used by the waste heat recovery device 31 and has become low pressure and low temperature is discharged to the outside. Is done.

  As the waste heat recovery device 31, a type that generates power by rotating the turbine with the flow velocity and pressure energy of the exhaust gas, and a boiler that is heated by the heat energy of the exhaust gas and drives the steam turbine with steam obtained by the boiler to generate power There are types. Thus, by using the energy of the exhaust gas of the internal combustion engine 13 as a power supply source, the fuel efficiency of the internal combustion engine can be further improved.

  FIG. 7 shows a single-shaft type propulsion device similar to that in FIG. 1, but it may be a type having a gear box similar to that in FIG. 6 and 7, members that are the same as those shown in FIG. 1 are given the same reference numerals.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 11 Propeller 12 Power transmission path 12a Propeller shaft 12b Main shaft 13 Internal combustion engine 14 Motor generator 15 Operation device 16 Governor 17 Electric equipment 18 Generator 21 Inverter 22 Battery 24 Load torque detector 25 Controller (control means)
26 Gearbox 31 Waste heat recovery device

Claims (4)

A propulsion device for a ship having a power transmission path that connects a propeller that applies thrust to the ship and a main shaft of an internal combustion engine,
A generator provided in the power transmission path and driven by the internal combustion engine to generate electric power;
An electric power supply unit to which electric power generated by the generator is supplied;
Load torque detection means for detecting load torque applied to the propeller;
The load torque detected by the load torque detecting means is compared with the output torque of the internal combustion engine, and when the load torque is lower than the output torque, the generator is operated by the internal combustion engine and the power supplied portion A ship propulsion device, characterized by comprising control means for supplying electric power to the ship. A propulsion device for a ship having a power transmission path that connects a propeller that applies thrust to the ship and a main shaft of an internal combustion engine,
An electric motor that is provided in the power transmission path and applies power to the propeller;
A power source for supplying power to the electric motor;
Load torque detection means for detecting load torque applied to the propeller;
The load torque detected by the load torque detection means is compared with the output torque of the internal combustion engine. When the load torque exceeds the output torque, the electric motor is operated by the electric power from the power source, and A propulsion device for a ship having control means for assisting power to a propeller. A propulsion device for a ship having a power transmission path that connects a propeller that applies thrust to the ship and a main shaft of an internal combustion engine,
A motor generator that is provided in the power transmission path and is driven by the internal combustion engine to generate electric power, while applying power to the propeller;
An electric power supply unit to which electric power generated by the motor generator is supplied;
A power source for supplying power to the motor generator;
Load torque detection means for detecting load torque applied to the propeller;
The load torque detected by the load torque detecting means is compared with the output torque of the internal combustion engine. When the load torque is lower than the output torque, the motor generator is operated by the internal combustion engine to supply the power And control means for assisting power to the propeller by operating the motor generator with power from the power source when the load torque exceeds the output torque. Ship propulsion device.   The marine vessel propulsion device according to claim 3, wherein the power supplied portion and the power source are batteries, and when the load torque is lower than the output torque, the power generated by the motor generator is charged to the battery, A marine vessel propulsion device, wherein when the load torque exceeds the output torque, the motor generator is operated by electric power of the battery to assist the propeller with power.

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