JP2022011720A - Propulsion mechanism of electric propulsion ship and electric propulsion ship - Google Patents

Abstract

To provide a propulsion mechanism which is a simpler structure than before and capable of stably operating in a propulsion mechanism of a DF engine driven by selecting a diffusing combustion and a premixed combustion, and of an electric propulsion ship powered by battery.SOLUTION: A propulsion mechanism 3 of an electric propulsion ship 1 comprises a generator 15 to generate electricity with a DF engine 23 driven by selecting diffusion combustion of liquid fuel or by premixed combustion of gas fuel, a battery 13, an electric motor 11 to drive a propeller 17 when power is supplied to the electric motor from the generator 15 or the battery 13, and a switching controller 9 to control the connecting selection of the generator 15, the battery 13, and the electric motor 11, and to control the distribution of power. The electric motor 11 is a DC motor. The switching controller 9 connects the electric motor 11 and the battery 13 when a load change of the electric motor 11 is beyond the predetermined threshold in the case that the motor 11 with the connected state to the generator 15 is in a power running by receiving power supply from the generator 15 while the DF engine 23 is driven by the premixed combustion.SELECTED DRAWING: Figure 1

Description

The present invention relates to a propulsion mechanism of an electric propulsion ship and an electric propulsion ship provided with the propulsion mechanism.

An electric propulsion ship is a ship that obtains propulsive force by driving a propeller with an electric motor. Since electric motors are easier to accelerate / decelerate and start / stop than diesel engines and turbine engines, they are superior in operability to ships propelled by these engines.

A diesel engine that diffuses and burns liquid fuel such as heavy oil is widely used as the power source for the generator that supplies power to the electric propulsion ship, but it is a DF (Dual Fuel) engine that can be driven by both liquid fuel and gas fuel. Has been considered as a power source in recent years.
This is to reduce the navigation cost by using the gas generated by vaporizing the liquefied gas, which is cargo, as gas fuel in the liquefied gas carrier without discarding it. It also has the purpose of reducing the amount of NO _x generated by driving it in a thermal cycle other than the diesel cycle using gas fuel.

On the other hand, when gas fuel is used, if the combustion method is premixed combustion, combustion is delayed as compared with diffusion combustion such as a diesel engine, so that abnormal combustion such as knocking or misfire is likely to occur. Therefore, it is difficult to drive the DF engine with gas fuel, especially when the load fluctuation applied to the electric motor is large, and it is necessary to drive it with liquid fuel.
Therefore, as a power source for the electric motor, a storage battery is provided in addition to the generator, and when the load fluctuation applied to the electric motor becomes large, the storage battery supplies electric power to the electric motor so that it can be driven by gas fuel regardless of the load fluctuation. An institution has been proposed (Patent Document 1).

Special Table 2017-532239

In the configuration of Patent Document 1, since the generator generates AC power and the motor is AC driven, the generator and the motor are connected by an inverter device having an AC / DC converter, a DC bus, and a DC / AC converter. The frequency of the power generated by the generator is adjusted for motor control. On the other hand, since the storage battery is a power source that supplies direct current, the storage battery is connected to the DC bus of the inverter device, and the power supplied by the storage battery is converted into alternating current by a direct current / alternating current converter and supplied to the electric motor.
With this structure, the structure of the inverter device becomes complicated, and since the storage battery is discharged to the DC bus of the inverter device, it is difficult to control the voltage of the DC bus and it is difficult to stabilize the operation of the inverter device. Therefore, the propulsion mechanism of Patent Document 1 has a problem that the structure is complicated and it is difficult to stabilize the operation.
The present invention has been made in view of the above problems, and is conventionally used in a propulsion mechanism of an electric propulsion ship using a storage battery as a power source and a generator that generates electricity with a DF engine that selectively drives diffusion combustion and premix combustion. The purpose is to provide a propulsion mechanism that has a simpler structure and is capable of stable operation.

In order to solve the above problems, the propulsion mechanism of the electric propulsion vessel of the present invention includes a generator, a storage battery, and a storage battery that generate power with a DF engine that is driven by selecting diffusion combustion of liquid fuel or premixed combustion of gas fuel. Electric propulsion including an electric motor that drives a propeller when power is supplied from the generator or the storage battery, and a switching control unit that controls connection selection and power distribution of the generator, the storage battery, and the electric motor. The electric motor is a DC motor, which is a propulsion mechanism of the ship, and the switching control unit generates the power while the DF engine is being driven by premixed combustion and the electric motor is connected to the generator. It is characterized in that when the load fluctuation of the electric motor exceeds a predetermined threshold value, the electric motor and the storage battery are connected when power is supplied from the machine.
Further, the electric propulsion vessel of the present invention has a propulsion mechanism of the electric propulsion vessel described above, a liquefied gas tank for storing liquefied gas, and the gas generated by vaporizing or forcibly vaporizing the liquefied gas. It is characterized by comprising a supply means for supplying the DF engine as fuel.

In this configuration, the load fluctuation of the DC motor becomes large while the DF engine is being driven by gas fuel, and when a predetermined threshold is exceeded, the switching control unit supplies DC current from the storage battery to the DC motor to drive the DC motor.
Therefore, when the DC motor is connected to the storage battery, a converter that converts DC power to AC power becomes unnecessary, and the structure is simpler than before and stable operation is possible.

According to the present invention, the structure of the propulsion mechanism of an electric propulsion ship powered by a DF engine that selectively drives diffusion combustion and premixed combustion and a storage battery is simpler and more stable than before. It is possible to provide a propulsion mechanism capable of operation.

It is a functional block diagram which shows the outline of the electric propulsion ship provided with the electric propulsion mechanism which concerns on this embodiment. It is a modification which shows the case where the generator of FIG. 1 is an AC generator. FIG. 1 is a diagram showing power supply when an electric motor is driven by a generator that generates electricity with the driving force of a DF engine. FIG. 1 is a diagram showing an electric power supply when an electric motor is driven by a storage battery. FIG. 1 is a diagram showing a case where an electric motor is regeneratively driven. It is a flow chart which shows an example of the navigation procedure of a ship using the electric propulsion mechanism which concerns on this embodiment.

Hereinafter, embodiments suitable for the present invention will be described in detail with reference to the drawings.
First, the configuration of the electric propulsion vessel 1 provided with the propulsion mechanism 3 according to the present embodiment will be described with reference to FIGS. 1 to 5.
Here, as the electric propulsion ship 1, it is a cargo ship that carries LNG (liquefied natural gas) as cargo, and is a propeller with an electric motor 11 that uses two power sources, a generator 15 that generates power with a DF engine 23 and a storage battery 13. An example is a cargo ship provided with a propulsion mechanism 3 for driving 17.
As shown in FIG. 1, the electric propulsion ship 1 includes a hull 5, a fuel tank 19, a liquefied gas tank 21, and a propulsion mechanism 3.

The hull 5 is a structure that becomes the hull of the electric propulsion ship 1, and is configured to surround the inside of the ship with a ship bottom, side walls, and an exposed deck. The specific hull shape, hull structure, arrangement of watertight bulkheads, etc. are appropriately designed according to the application of the electric propulsion ship 1.

The fuel tank 19 is a tank for storing the fuel of the electric propulsion vessel 1. The shape, structure, capacity, and installation position of the fuel tank 19 are appropriately set in consideration of the cruising range required for the electric propulsion ship 1, the displacement and stability of the hull 5, and the load weight of the cargo.
The fuel stored in the fuel tank 19 is a liquid fuel. The liquid fuel here means the fuel supplied to the DF engine 23 in a liquid state. In the electric propulsion vessel 1, petroleum-based liquid fuel such as heavy oil is mainly used as the liquid fuel. C heavy oil is mainly used for large vessels that carry LNG as cargo, but A heavy oil may be used for small vessels.

The liquefied gas tank 21 is a tank for storing LNG as a liquefied gas. Liquefied gas is a gas that is cooled or compressed to a liquid at normal temperature and pressure.
Since the liquefied gas is cargo in the electric propulsion ship 1, the shape, structure, capacity and installation position of the liquefied gas tank 21 are the displacement and stability of the hull 5, the load weight of the liquefied gas, and the temperature and pressure of the liquefied gas at the time of loading. It is set appropriately in consideration of. In FIG. 1, a spherical tank independent of the hull 5 such as an independent spherical tank is schematically shown, but a structure such as a membrane type in which the pressure and weight of the liquefied gas are held by the hull 5 may be used.
Although liquefied gas is cargo, it is also used as gas fuel in the electric propulsion ship 1. The gas fuel means a fuel supplied to the DF engine 23 in a gaseous state. The reason why the liquefied gas, which is cargo, can be used as gas fuel is that a part of the liquefied gas is vaporized by the invading heat due to the temperature difference between the inside of the liquefied gas tank 21 during navigation and the outside air, and the temperature rise due to the kinetic energy due to the movement of the hull, and the BOG. This is because it becomes a gas fuel called (Boil Off Gas). This is also because the liquefied gas may be forcibly vaporized using a vaporizer (not shown) and used as a gas fuel.
The liquefied gas tank 21 is provided with a pipe for supplying the BOG vaporized from the LNG as gas fuel to the DF engine 23 and a supply means 61 provided with a pressurizing mechanism for adjusting the pressure of the gas fuel, if necessary.

The propulsion mechanism 3 is a mechanism for propelling the electric propulsion ship 1, and includes a DF engine 23, a generator 15, a storage battery 13, an electric motor 11 which is a DC motor, a speed reducer 7, a propeller 17, and a switching control unit 9.

The DF engine 23 is an internal combustion engine that selectively drives diffuse combustion of liquid fuel or premixed combustion of gas fuel.
Liquid fuel is supplied to the DF engine 23 from the fuel tank 19, and BOG generated by vaporizing the liquefied gas stored inside the liquefied gas tank 21 is supplied as gas fuel.

When the DF engine 23 is driven by diffusion combustion of liquid fuel, the combustion method is compression ignition, and the combustion cycle is a diesel cycle.
When the DF engine 23 is driven by liquid fuel, the thermal efficiency is superior to that when gas fuel is used because it is a diesel cycle, and knocking and misfire do not occur, so that it is resistant to load fluctuations of the electric motor 11.

When the DF engine 23 is driven by premixed combustion of gas fuel, the gas fuel is mixed with intake air in the front chamber of a combustion chamber such as an intake manifold (not shown in advance) and then introduced into the combustion chamber. The combustion method is an ignition type, and the combustion cycle is mainly the Otto cycle.
When driving the DF engine 23 with gas fuel, it is advantageous that the BOG can be effectively used.

The DF engine 23 can be driven by selecting diffusion combustion of liquid fuel or premixed combustion of gas fuel, can obtain the power required for propulsion of the electric propulsion ship 1, and has a structure and shape within a range that can be mounted on the electric propulsion ship 1. , Dimensions and installation position are set appropriately. Normally, the size is determined within the range that can be mounted in the engine room of the hull 5. Since the combustion gas and the intake air are mixed in the 2-stroke engine during scavenging, it is not suitable for premixing the gas fuel, and the DF engine 23 is preferably a 4-stroke engine.
Switching between liquid fuel and gas fuel is, for example, manual or automatic. Normally, it is driven by liquid fuel when the engine is started and when the engine is stopped, and either liquid fuel or gas fuel is selected when sailing.

The generator 15 is one of the power sources of the electric motor 11, and is a generator that generates electricity by transmitting the power of the DF engine 23. The generated electric power is supplied to the electric motor 11 and used for propulsion of the electric propulsion ship 1.
The generator 15 is provided with an input shaft to which the power of the DF engine 23 is transmitted, can generate the electric power required for propulsion of the electric propulsion ship 1, and appropriately sets the structure, shape, dimensions, and installation position within the range that can be stored in the hull 5. can. Normally, it is arranged in the engine room of the hull 5 adjacent to the DF engine 23.

The generator 15 is preferably a DC generator. A DC generator means a generator whose generated power is DC.
Since the electric motor 11 of the propulsion mechanism 3 is also DC, when the generator 15 is a DC generator, the power generated by the generator is supplied to the electric motor 11 as DC.
Therefore, when the electric power generated by the generator 15 is supplied to the electric motor 11, a converter for AC / DC conversion becomes unnecessary, and the structure becomes simple as compared with the case where the generator 15 generates AC electric power.

The generator 15 may be an alternator. The alternator means an alternator whose generated power is an alternating current.
Since the electric motor 11 of the propulsion mechanism 3 is a direct current, when the generator 15 is an alternating current generator, the power output unit of the generator 15 is connected to the converter 25 as shown in FIG. The converter 25 is a converter that converts AC power into DC power, and the AC power generated by the generator 15 is output to the converter 25, converted into DC power, and supplied to the electric motor 11.
When the generator 15 is an AC generator, the existing ship's generator is mainly an AC generator, which is advantageous in that the range of choices of types and structures is wider than that of the DC generator.
In the following description, unless otherwise specified, the case where the generator 15 is a DC generator will be described as an example.

The storage battery 13 shown in FIG. 1 is one of the power sources of the electric motor 11, and is a battery that can be repeatedly charged and discharged.
The storage battery 13 has a capacitance that can charge and discharge the electric power required for propulsion of the electric propulsion ship 1 and the number of charge / discharge cycles. , The installation position is determined. As a specific type of battery, a lithium ion secondary battery can be exemplified. The electric power discharged by the storage battery 13 is direct current.

The electric motor 11 is a motor that transmits rotational force to the propeller 17 by rotating a rotor (not shown) when electric power is supplied from the generator 15 or the storage battery 13 to rotate the motor.
The electric motor 11 can generate the rotational force required for propulsion of the electric propulsion ship 1 by the electric power of the generator 15 or the storage battery 13 and transmit it to the propeller 17, and if it can be stored in the hull 5, the structure, shape, dimensions, and installation. The position can be set as appropriate.

However, the electric motor 11 is a DC motor. The reason is as follows.
An electric propulsion engine that provides a generator 15 and a storage battery 13 as a power source for a motor that drives a propeller 17 of an electric propulsion ship 1 and uses the storage battery 13 as a power source when the load fluctuation becomes large while driving the DF engine 23 with gas fuel is known. Is.
On the other hand, since the electric power discharged by the storage battery 13 is direct current, when the motor for driving the propeller 17 is an AC motor, the storage battery 13 and the AC motor are connected via a DC / AC converter, and the DC discharged by the storage battery 13 is connected. Power needs to be converted to AC power. In particular, when the generator 15 of the DF engine 23 is an AC generator, it is provided with an AC / DC converter, a DC bus, and a DC / AC converter that adjust the frequency of the AC power supplied from the generator 15 to the electric motor 11. An inverter device connects between the generator 15 and the electric motor 11. In order to connect the storage battery 13 to the DC / AC converter with this structure, it is necessary to connect the storage battery 13 to the DC bus, and the power flowing through the DC bus is not stable, so that the operation of the inverter device tends to be unstable.
On the other hand, in the propulsion mechanism 3 according to the present embodiment, the electric motor 11 is a DC motor, and it is not necessary to connect the storage battery 13 and the electric motor 11 via a DC / AC converter, and the structure can be simplified.
Further, since the electric motor 11 is a direct current motor, no inverter device is required regardless of whether the generator 15 is direct current or alternating current. Therefore, stable operation is possible without an unstable structure in which the storage battery 13 is connected to the DC bus of the inverter device.

The speed reducer 7 is a power transmission mechanism provided with a gear mechanism (not shown) that adjusts the direction and rotation speed of the rotational force generated by the electric motor 11 and transmits the rotational force to the propeller 17. The input shaft of the speed reducer 7 is connected to the output shaft of the electric motor 11, and power is transmitted from the electric motor 11. The output shaft of the speed reducer 7 is connected to the boss of the propeller 17 to rotate the propeller 17 in a desired direction and rotation speed.
The speed reducer 7 can transmit the rotational force required for navigation of the electric propulsion ship 1 to the propeller 17, and if it can be stored in the hull 5, the structure, shape, dimensions, and installation position can be appropriately set.

The propeller 17 is a propulsion device that propels the electric propulsion ship 1 by converting the rotational force transmitted from the speed reducer 7 into a propulsive force acting in the navigation direction of the ship. The propeller 17 includes a boss connected to the output shaft of the speed reducer 7 to transmit the rotational force, and a propeller blade projecting from the boss in a direction orthogonal to the rotational axis to convert the rotational force into propulsive force.
The propeller 17 can generate the propulsive force required for the navigation of the electric propulsion vessel 1, and the structure, shape, and dimensions can be appropriately set within a range that does not interfere with other structures such as the hull 5 and the rudder.

The switching control unit 9 is a device that controls the selection of the connection of the power line between the generator 15, the storage battery 13, and the electric motor 11 and the distribution of the power, and is connected to these devices by the power line.

Since the switching control unit 9 is a device that selects and distributes DC power connection, it is connected to the storage battery 13 and the electric motor 11 without going through an AC / DC converter such as an inverter device or a converter. ..
Even when the generator 15 is a DC generator, the switching control unit 9 is connected to the generator 15 without going through a converter such as an inverter device or a converter.
When the generator 15 is an alternator, the switching control unit 9 is connected to the generator 15 via the converter 25 shown in FIG.
If the switching control unit 9 can control the selection of the connection of the power line between the generator 15, the storage battery 13, and the electric motor 11 and the distribution of the power, a device combining a known switchboard and the control device may be used. ..

The switching control unit 9 controls the selection of the connection of the power line between the generator 15, the storage battery 13, and the electric motor 11 and the distribution of the power based on the following conditions.
First, when the DF engine 23 is undergoing diffusion combustion using liquid fuel and the electric motor 11 is connected to the generator 15 and is powered by the power supplied from the generator 15, the switching control unit 9 Maintains a state in which the generator 15 is connected to the electric motor 11. In this state, as shown in FIG. 3, the DC power generated by the generator 15 is supplied to the electric motor 11 via the switching control unit 9, and the electric motor 11 powers. When the electric motor 11 powers, a rotational force is generated and transmitted to the propeller 17 via the speed reducer 7. The propeller 17 navigates the electric propulsion ship 1 by converting the transmitted rotational force into a propulsive force.

Whether or not the DF engine 23 is in diffusion combustion is configured so that the DF engine 23 outputs a signal indicating the combustion state of the DF engine 23 to the switching control unit 9, and the switching control unit 9 determines from the received signal. May be good. Alternatively, the switching control unit 9 can determine whether the switching control unit 9 is provided with a manual switch for selecting whether the DF engine 23 is in diffusion combustion or premixed combustion, and the engineer who operates the DF engine 23 operates the switch. You may do so.

Since the storage battery 13 is not used as a power source for the electric motor 11 during diffusion combustion using liquid fuel, the switching control unit 9 does not connect the storage battery 13 to the electric motor 11. This is because diffusion combustion using liquid fuel has higher followability to load fluctuations than premixed combustion using gas fuel, so sufficient power can be supplied to the electric motor 11 without using the storage battery 13 as a power source. Because.

However, when the charge rate of the storage battery 13 becomes equal to or less than a predetermined lower limit charge rate, the switching control unit 9 supplies at least a part of the power generated by the generator 15 to the storage battery 13 to supply the storage battery 13. It may be charged until the preset upper limit charge rate is reached.
When the charge rate of the storage battery 13 becomes equal to or less than the lower limit in this way, the storage battery 13 can be charged by using the generator 15 to prevent the storage battery 13 from running out.
The charge rate of the storage battery 13 can be obtained by measuring the discharge voltage and calculating the capacitance by referring to the discharge curve or the like.

When the DF engine 23 is undergoing premixed combustion using gas fuel and the electric motor 11 is connected to the generator 15 and is powered by the power supplied from the generator 15, the switching control unit 9 is driven. The following control is performed.
First, the switching control unit 9 connects the electric motor 11 and the storage battery 13 when the load fluctuation of the electric motor 11 exceeds a predetermined threshold value. The predetermined threshold value is a value at which knocking or misfire may occur in the DF engine 23 during premixed combustion.
The load fluctuation referred to here is specifically a fluctuation in the load torque of the electric motor 11, and may be calculated from a load factor or the like, or may be actually measured by a torque sensor or the like.

When the electric motor 11 and the storage battery 13 are connected, electric power is supplied from the storage battery 13 to the electric motor 11 as shown in FIG. 4, and the electric motor 11 is driven. The storage battery 13 has higher followability to load fluctuations as compared with premixed combustion using gas fuel. Therefore, by supplying electric power from the storage battery 13 to the electric motor 11 when the load fluctuation exceeds the threshold value, even if the load fluctuation that makes it difficult to drive the DF engine 23 stably by premixed combustion occurs, the DF engine 23 There is no need to switch to diffusion combustion. Therefore, the conditions of load fluctuation that can drive the DF engine 23 by premixed combustion can be broadened.
Further, since the electric motor 11 is direct current, there is no need for a converter that converts DC power into AC power when connecting the electric motor 11 and the storage battery 13. Therefore, the structure is simpler than before and stable operation is possible.

When the storage battery 13 is connected to the electric motor 11, the switching control unit 9 does not have to connect the generator 15 to the electric motor 11. In this case, the switching control unit 9 may connect the generator 15 to the storage battery 13 without connecting the generator 15 to the electric motor 11 and charge the storage battery 13 with the generated electric power. Specifically, the generator 15 supplies the electric power corresponding to the electric power consumed by the storage battery 13 to drive the electric motor 11 to the storage battery 13 to charge the electric power. In this case, it is possible to prevent the storage battery 13 from running out while the storage battery 13 is supplying electric power to the electric motor 11. However, in this structure, since the electric motor 11 is driven only by the storage battery 13, the output of the storage battery 13 needs to be equal to or higher than the maximum output of the generator 15.

When the storage battery 13 is connected to the electric motor 11, the generator 15 may also supply electric power to the electric motor 11 while maintaining the state in which the generator 15 is connected to the electric motor 11. In this case, the storage battery 13 may supply the electric motor 11 with the electric power insufficient for the electric power supplied by the generator 15 to the electric motor 11. This configuration is advantageous in that the storage battery 13 can be easily miniaturized because the capacity of the storage battery 13 may be a capacity corresponding to the shortage of the electric power supplied by the generator 15.

When the DF engine 23 is in premixed combustion using gas fuel, the electric motor 11 is connected to the generator 15 to receive power supply and power, and the load fluctuation of the electric motor 11 is equal to or less than the threshold value, switching control is performed. The unit 9 does not connect the electric motor 11 to the storage battery 13 as in the case of diffusion combustion. In this case, the switching control unit 9 maintains a state in which the generator 15 is connected to the electric motor 11.
This is because when the load fluctuation of the electric motor 11 is equal to or less than the threshold value, the DF engine 23 can operate stably even in the case of premixed combustion. Further, if the storage battery 13 is continuously used as a power source, the battery may run out.
When the electric motor 11 and the generator 15 are connected, electric power is supplied from the generator 15 to the electric motor 11 to drive the electric motor 11.

When the charge rate of the storage battery 13 is equal to or less than a predetermined lower limit charge rate during premixed combustion, the switching control unit 9 supplies at least a part of the power generated by the generator 15 to the storage battery 13. The storage battery 13 may be charged until it reaches a preset upper limit charge rate. The reason is to prevent the battery from running out as in the case of charging the storage battery 13 during diffusion combustion.

When the electric motor 11 is regeneratively driven, specifically, when the power generated by the regenerative power generation is supplied from the electric motor 11 to the switching control unit 9, the switching control unit 9 connects the electric motor 11 to the storage battery 13. , The regenerative power supplied as shown in FIG. 5 is charged into the storage battery 13. The case where the electric motor 11 is regeneratively driven includes a case where the propeller 17 rotates in the reverse direction to the time of navigation due to the influence of waves and the like. In this case, if there is no device that consumes the regenerative power, the regenerative power flows into the switching control unit 9, the generator 15, and the storage battery 13 as reverse power, and the breaker is cut off or the device is burnt due to heating due to an increase in power. This is because it causes.
As a method of consuming the regenerative power, there is a method of consuming it as heat with a resistor, but by charging the storage battery 13 with the regenerative power, a part of the regenerative power conventionally consumed as heat by the resistor is electrically propelled. It can be used as electric power for navigation of ship 1.
When charging the storage battery 13 with regenerative power, it is preferable not to connect the electric motor 11 to the generator 15. This is because there is a possibility that reverse power will flow into the generator 15 when connected. Further, when the charge rate of the storage battery 13 is equal to or higher than the upper limit charge rate while the electric motor 11 is being regenerated, or when the regenerative power of the power exceeding the discharge capacity of the storage battery 13 is generated, the regenerative power is transferred to the storage battery 13. It is consumed as heat by a resistor (not shown) without charging.

When the electric motor 11 is connected to the storage battery 13, the condition for disconnecting the connection is the case where the connection condition is no longer satisfied. Specifically, when the electric motor 11 connects the electric motor 11 to the storage battery 13 during the regenerative power generation, the condition for disconnecting the connection is when the regenerative power generation is stopped or when charging becomes impossible.
When the electric motor 11 is connected to the storage battery 13 while the electric motor 11 is running, the condition for disconnecting the connection is that the DF engine 23 is undergoing diffusion combustion using liquid fuel. Alternatively, the load fluctuation of the electric motor 11 becomes equal to or less than the threshold value during the premixed combustion of the DF engine 23 using the gas fuel.
The above is the description of the structure of the electric propulsion ship 1 provided with the propulsion mechanism 3 in the present embodiment.

Next, an example of the navigation procedure of the electric propulsion vessel 1 provided with the propulsion mechanism 3 according to the present embodiment will be described with reference to FIG. In the following description, even when the electric motor 11 and the storage battery 13 are connected, the connection between the electric motor 11 and the generator 15 is maintained, and the power supplied by the generator 15 to the electric motor 11 is insufficient for the storage battery 13. Take as an example the procedure of supplying to the electric motor 11.
First, the switching control unit 9 determines whether or not the electric motor 11 is in regenerative power generation based on whether or not the reverse power is supplied from the electric motor 11, and proceeds to S2 if the electric motor 11 is in the regenerative power generation, and to S3 if the electric motor 11 is not in the regenerative power generation. Proceed (S1 in FIG. 6).
When it is determined in S1 that regenerative power generation is in progress, the switching control unit 9 determines whether or not the storage battery 13 can charge the regenerative power, specifically, the charge rate of the storage battery 13 is less than the upper limit charge rate, and the regenerative power is the storage battery 13. It is determined whether the discharge capacity is exceeded (S2 in FIG. 6). When it is determined that the battery can be charged, the storage battery 13 and the electric motor 11 are connected, and the regenerative power is charged to the storage battery 13 and returned (S2-2 in FIG. 6). At this time, the switching control unit 9 does not connect the electric motor 11 and the generator 15. If it is determined in S2 that the battery cannot be charged, the storage battery 13 and the electric motor 11 are not connected, but a resistor (not shown) and the electric motor 11 are connected to consume the regenerated power as heat energy and return (S2 in FIG. 6). -3).

When it is determined in S1 that regenerative power generation is not in progress, the switching control unit 9 connects the electric motor 11 and the generator 15 and drives the electric motor 11 with the power supplied by the generator 15 (S3 in FIG. 6). At this time, if the electric motor 11 and the storage battery 13 are connected due to reasons such as regenerative power generation until immediately before, the connection is canceled. Next, the switching control unit 9 determines whether or not the DF engine 23 is in gas combustion, that is, whether or not it is in premixed combustion using gas fuel, and if it is in gas combustion, proceeds to S5, and if it is not in gas combustion. Proceeds to S7-2 (S4 in FIG. 6).
When it is determined in S4 that the DF engine 23 is burning gas, the switching control unit 9 acquires the load fluctuation of the electric motor 11 (S5 in FIG. 6). Further, the switching control unit 9 determines whether or not the load fluctuation acquired in S5 exceeds a predetermined threshold value, proceeds to S7 if it is determined to exceed the threshold value, and proceeds to S7-2 if it is determined not to exceed the threshold value. Proceed (S6 in FIG. 6).
When it is determined in S6 that the load fluctuation exceeds the threshold value, the switching control unit 9 connects the storage battery 13 and the electric motor 11, and the electric power supplied by the storage battery 13 boosts the load fluctuation amount to drive the electric motor 11 in S8. (S7 in FIG. 6).

When it is determined in S4 that the DF engine 23 is not gas combustion, when it is determined in S6 that the load fluctuation does not exceed the threshold value, the switching control unit 9 does not connect the storage battery 13 and the electric motor 11, but is already connected. Disconnects and proceeds to S8 (S7-2 in FIG. 6).
When S7 or S7-2 is executed, the switching control unit 9 acquires the charge rate of the storage battery 13 (S8 in FIG. 6). If the acquired charge rate is not less than or equal to the lower limit charge rate, the process proceeds to S10, and if it is not less than or equal to the lower limit charge rate, the process returns (S9 in FIG. 6).
When it is determined in S9 that the charge rate is equal to or less than the lower limit charge rate, the switching control unit 9 connects the generator 15 and the storage battery 13, charges the storage battery 13 until the charge rate of the storage battery 13 reaches the upper limit charge rate, and returns. (S10 in FIG. 6).
The above is an explanation of an example of the navigation procedure of the electric propulsion vessel 1 provided with the propulsion mechanism 3 according to the present embodiment.

As described above, in the propulsion mechanism 3 of the present embodiment, when the load fluctuation becomes large while the DF engine 23 is being driven by gas fuel, the switching control unit 9 supplies a direct current from the storage battery 13 to the electric motor 11 which is a direct current motor. Drive.
Therefore, when the storage battery 13 is connected to the electric motor 11, a converter that converts DC power into AC power becomes unnecessary, and the structure is simpler and more stable operation than before is possible.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the embodiments. It is natural for a person skilled in the art to come up with various modifications and improvements within the scope of the technical idea of the present invention, and these are also included in the present invention.

1: Electric propulsion ship 3: Propulsion mechanism 5: Hull 7: Reducer 9: Switching control unit 11: Electric motor 13: Storage battery 15: Generator 17: Propeller 19: Fuel tank 21: Liquefied gas tank 23: DF engine 25: Converter 61: Supply means

Claims (8)

A generator that generates electricity with a DF engine that selectively drives diffuse combustion of liquid fuel or premixed combustion of gas fuel, a storage battery, and an electric motor that drives a propeller when power is supplied from the generator or the storage battery. A propulsion mechanism for an electric propulsion vessel, comprising a switching control unit that controls connection selection and power distribution of the generator, the storage battery, and the electric motor.
The electric motor is a DC motor and
When the switching control unit operates by receiving electric power from the generator while the DF engine is being driven by premixed combustion and the electric motor is connected to the generator.
A propulsion mechanism for an electric propulsion ship, characterized in that the electric motor and the storage battery are connected when the load fluctuation of the electric motor exceeds a predetermined threshold value. The propulsion mechanism for an electric propulsion ship according to claim 1, wherein the generator is a DC generator. The propulsion mechanism for an electric propulsion ship according to claim 1, wherein the generator is an AC generator, and is connected to the switching control unit via a converter that converts the generated AC power into DC power. When the switching control unit connects the electric motor and the storage battery,
The generator is connected to the storage battery without being connected to the electric motor, and the generator supplies and charges the storage battery with electric power corresponding to the electric power consumed by driving the electric motor. The propulsion mechanism for an electric propulsion vessel according to any one of claims 1 to 3. When the electric motor and the storage battery are connected, the switching control unit maintains the state in which the generator is connected to the electric motor.
The propulsion mechanism for an electric propulsion ship according to any one of claims 1 to 3, wherein the storage battery supplies electric power insufficient for the electric power supplied to the electric motor by the generator. The switching control unit
When the charge rate of the storage battery becomes equal to or less than a predetermined lower limit charge rate, at least a part of the power generated by the generator is supplied to the storage battery to bring the storage battery to a preset upper limit charge rate. The propulsion mechanism for an electric propulsion vessel according to any one of claims 1 to 5, which is charged until it reaches the limit. The switching control unit
The electricity according to any one of claims 1 to 5, wherein when the electric motor is supplied with electric power by regenerative power generation, the electric motor is connected to the storage battery and the supplied electric power is charged to the storage battery. Propulsion mechanism of the propulsion ship. The propulsion mechanism of the electric propulsion vessel according to any one of claims 1 to 7.
A liquefied gas tank that stores liquefied gas and
An electric propulsion vessel comprising a supply means for supplying the gas generated by vaporizing or forcibly vaporizing the liquefied gas to the DF engine as the gas fuel.

Images