Engine System

Abstract

To provide an engine system capable of inhibiting unburned gas fuel flowing from an engine into an exhaust pipe from burning in the exhaust pipe.SOLUTION: An engine system 100 includes an engine 1, an exhaust pipe 19, a gas introduction part 21 and a supercharger 11. The engine 1 generates power by burning gas fuel. In the exhaust pipe 19, exhaust gas discharged from the engine 1 flows. The gas introduction part 21 introduces air or inert gas into the exhaust pipe 19. The gas introduction part 21 is connected to an upstream side of the supercharger 11 in the exhaust pipe 19.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine system. [Background technology]

[0002] In the internal combustion engine control device described in Patent Document 1, during catalyst warm-up, the exhaust gas temperature in the exhaust pipe is raised to a temperature at which rich components such as HC and CO in the exhaust gas can be after-burned. Then, secondary air (outside air) is introduced into the exhaust pipe by a secondary air introduction device to cause after-burning. As a result, the rich components in the high-temperature exhaust gas emitted from the engine are mixed with oxygen in the secondary air introduced by the secondary air introduction device, causing after-burning to occur naturally in the exhaust pipe upstream of the catalyst, and the heat of combustion quickly warms up the catalyst. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-263050 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the control device for an internal combustion engine described in Patent Document 1, rich components in the exhaust gas are mixed with oxygen in the secondary air and then afterburned. Therefore, even if unburned gaseous fuel flows into the exhaust pipe from the engine, the unburned gaseous fuel also burns in the exhaust pipe. As a result, the combustion of the unburned gaseous fuel may damage the turbocharger and the catalyst.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide an engine system that can prevent unburned gaseous fuel that flows from the engine into the exhaust pipe from burning within the exhaust pipe. [Means for solving the problem]

[0006] According to one aspect of the present invention, an engine system includes an engine, an exhaust pipe, a gas introduction section, and a supercharger. The engine generates power by combusting gaseous fuel. Exhaust gas discharged from the engine flows through the exhaust pipe. The gas introduction section introduces air or an inert gas into the exhaust pipe. The gas introduction section is connected to the exhaust pipe upstream of the supercharger. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an engine system that can suppress unburned gaseous fuel that has flowed from the engine into the exhaust pipe from being burned in the exhaust pipe. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of an engine system according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing an engine system according to a first embodiment. [Figure 3] 4 is a time chart showing changes in various states of the engine system according to the first embodiment. [Figure 4] 4 is a flowchart showing a method for controlling a gas introduction part according to the first embodiment. [Figure 5] 10 is a flowchart showing a method for controlling a gas introduction part according to a first modified example of the first embodiment. [Figure 6] 10 is a flowchart showing a method for controlling a gas introduction part according to a second modified example of the first embodiment. [Figure 7] 10 is a flowchart showing a method for controlling a gas introduction part according to a third modified example of the first embodiment. [Figure 8] FIG. 4 is a diagram showing the configuration of an engine system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and description thereof will not be repeated.

[0010] (Embodiment 1) First, an engine system 100 according to a first embodiment of the present invention will be described with reference to Fig. 1. The engine system 100 shown in Fig. 1 generates power by burning gaseous fuel. The gaseous fuel is not particularly limited, but may be, for example, hydrogen, ammonia, or natural gas. The natural gas may be, for example, vaporized liquefied natural gas (LNG). The engine system 100 may be, for example, mounted on a vehicle, installed inside a building, or installed outdoors. The vehicle may be, for example, a ship, an automobile, a railroad car, or an airplane.

[0011] The following description will be given taking hydrogen fuel as an example of gaseous fuel. Also, the description will be given taking a ship 200 as an example of a vehicle on which the engine system 100 is installed. In the following description, the ship 200 can be read as "vehicle," hydrogen fuel can be read as "gaseous fuel," and hydrogen can be read as "fuel gas" or "fuel."

[0012] 1, a vessel 200 includes an engine system 100. The engine system 100 generates power by burning hydrogen fuel.

[0013] The engine system 100 includes an engine 1, a liquefied hydrogen tank 3, a vaporizer 5, a hydrogen flow rate regulator 7, a hydrogen fuel supply pipe 9, a turbocharger 11, an intercooler 13, an air intake pipe 15, an intake manifold 17, an exhaust pipe 19, a gas introduction section 21, and a generator 27. The engine system 100 preferably further includes a temperature detector 23 and a pressure detector 25.

[0014] The engine 1 generates power by burning hydrogen fuel. The engine 1 then drives the generator 27. As a result, the generator 27 generates electric power. In other words, the generator 27 generates electric power using the engine 1. The generator 27 then supplies electric power to, for example, auxiliary equipment. The auxiliary equipment is an example of a load device for the generator 27. The auxiliary equipment is not particularly limited, but is, for example, a solenoid valve, an electric motor, lighting equipment, or air conditioning equipment. Furthermore, for example, if the ship 200 generates propulsion power using electric power, the generator 27 supplies electric power to a propulsion motor that drives a propeller. The propulsion motor is an example of a load device for the generator 27.

[0015] The hydrogen fuel supply pipe 9 supplies gaseous hydrogen fuel to the engine 1. Specifically, a liquefied hydrogen tank 3, a vaporizer 5, and a hydrogen flow rate adjuster 7 are arranged in this order from upstream to downstream. The liquefied hydrogen tank 3 stores liquid hydrogen fuel. The vaporizer 5 vaporizes the liquid hydrogen fuel supplied from the liquefied hydrogen tank 3 and supplies the gaseous hydrogen fuel to the hydrogen fuel supply pipe 9. Note that the hydrogen fuel may be stored and stored as compressed high-pressure gas. In this case, for example, the engine system 100 may include a compressed hydrogen tank that stores hydrogen fuel as compressed high-pressure gas instead of the liquefied hydrogen tank 3, and may not include the vaporizer 5.

[0016] The hydrogen flow rate adjuster 7 adjusts the supply amount of hydrogen fuel flowing through the hydrogen fuel supply pipe 9. The hydrogen flow rate adjuster 7 is, for example, a gas valve unit (GVU). The gas valve unit includes, for example, a plurality of valves, a gas filter, a gas regulator, and pipes. In the gas valve unit, for example, one or more valves constitute a pressure regulating valve.

[0017] The intake pipe 15 supplies air outside the engine 1 to the engine 1 via the turbocharger 11, the intercooler 13, and the intake manifold 17. Specifically, the turbocharger 11 and the intercooler 13 are arranged in this order from upstream to downstream of the intake air. The turbocharger 11 compresses air outside the engine 1 and causes the air to flow through the intake pipe 15 at a pressure higher than atmospheric pressure. The intercooler 13 cools the air compressed by the turbocharger 11 and supplies it to the intake manifold 17. The intake manifold 17 supplies the compressed and cooled air to the engine 1. Specifically, the engine 1 has multiple cylinders 1a. For simplicity of illustration, only one cylinder 1a is shown in FIG. 1. The intake manifold 17 supplies the compressed and cooled air to each cylinder 1a. Note that the engine 1 may have only one cylinder 1a. In this case, the intake manifold 17 can be omitted.

[0018] Exhaust gas emitted from the engine 1 flows through the exhaust pipe 19. That is, the exhaust pipe 19 discharges the exhaust gas to the outside of the engine 1. The exhaust gas is utilized by the turbocharger 11. Specifically, the turbocharger 11 includes a turbine 111 and a compressor 112. The turbine 111 is disposed in the exhaust pipe 19, and the compressor 112 is disposed in the intake pipe 15. The turbine 111 is rotated by the exhaust gas flowing through the exhaust pipe 19, and transmits the rotational force to the compressor 112. The compressor 112 is driven by the rotational force of the turbine 111 to compress the air flowing through the intake pipe 15.

[0019] The temperature detection unit 23 detects the temperature of the exhaust gas flowing through the exhaust pipe 19. Specifically, the temperature detection unit 23 detects the temperature of the exhaust gas upstream of the turbocharger 11 (specifically, the turbine 111) inside the exhaust pipe 19. In the example of FIG. 1 , the temperature detection unit 23 detects the temperature of the exhaust gas upstream of the turbine 111 in the exhaust pipe 19 and downstream of the connection point between a communication pipe 211 (described later) and the exhaust pipe 19. The temperature detection unit 23 is, for example, a temperature sensor.

[0020] The pressure detection unit 25 detects the pressure of exhaust gas flowing through the exhaust pipe 19. Specifically, the pressure detection unit 25 detects the pressure of exhaust gas upstream of the turbocharger 11 (specifically, the turbine 111) inside the exhaust pipe 19. In the example of FIG. 1 , the pressure detection unit 25 detects the pressure of exhaust gas upstream of the turbine 111 in the exhaust pipe 19 and downstream of a connection point between a communication pipe 211 (described later) and the exhaust pipe 19. The pressure detection unit 25 is, for example, a pressure sensor.

[0021] The gas introduction section 21 introduces air into the exhaust pipe 19. Therefore, even if hydrogen fuel that has not been burned in the engine 1 (unburned hydrogen fuel) flows into the exhaust pipe 19, the unburned hydrogen fuel that flows from the intake passage 63 into the exhaust pipe 19 can be diluted with air. This makes it possible to reduce the concentration of the unburned hydrogen fuel that flows into the exhaust pipe 19. As a result, according to the first embodiment, it is possible to suppress combustion of the unburned hydrogen fuel that flows into the exhaust pipe 19 from the engine 1. Furthermore, the temperature of the unburned hydrogen fuel that flows into the exhaust pipe 19 is lowered by the air introduced into the exhaust pipe 19. As a result, it becomes more difficult for the unburned hydrogen fuel to ignite, which further suppresses combustion of the unburned hydrogen fuel that flows into the exhaust pipe 19.

[0022] In this specification, hydrogen fuel that has not been combusted in the engine 1 (specifically, the combustion chamber 61) is defined as “unburned hydrogen” or “unburned hydrogen fuel.” The air that the gas inlet 21 introduces into the exhaust pipe 19 is air for diluting the unburned hydrogen within the exhaust pipe 19.

[0023] In particular, if the unburned hydrogen in the exhaust pipe 19 is diluted with air so that the concentration of unburned hydrogen in the exhaust pipe 19 becomes less than 4%, combustion of the unburned hydrogen in the exhaust pipe 19 can be reliably prevented. This is because hydrogen does not ignite if the hydrogen concentration is less than 4%. Therefore, it is preferable that the gas introduction unit 21 introduces air into the exhaust pipe 19 so that the concentration of unburned hydrogen in the exhaust pipe 19 becomes less than 4%. In other words, it is preferable that the gas introduction unit 21 introduces air into the exhaust pipe 19 so that the concentration of unburned hydrogen in the exhaust pipe 19 is outside the flammable range.

[0024] However, even if the concentration of unburned hydrogen in exhaust pipe 19 does not become less than 4% after air is introduced into exhaust pipe 19, the concentration of unburned hydrogen in exhaust pipe 19 will be lower than before air was introduced into exhaust pipe 19. Therefore, the auto-ignition temperature of unburned hydrogen will be higher after air is introduced into exhaust pipe 19 than before air was introduced into exhaust pipe 19. As a result, combustion of unburned hydrogen in exhaust pipe 19 can be suppressed.

[0025] Specifically, the gas introduction section 21 introduces air compressed by the turbocharger 11 from the intake pipe 15 into the exhaust pipe 19. That is, in the first embodiment, by sending air at a pressure higher than atmospheric pressure from the intake pipe 15 to the exhaust pipe 19, it is possible to more reliably introduce air into the exhaust pipe 19 against the pressure of the exhaust gas. Therefore, it is possible to more reliably reduce the concentration of unburned hydrogen that has flowed into the exhaust pipe 19. As a result, it is possible to more effectively suppress the combustion of unburned hydrogen in the exhaust pipe 19.

[0026] More specifically, the gas introduction section 21 includes a communication pipe 211 and a flow rate adjustment section 212 .

[0027] The communicating pipe 211 communicates between the intake pipe 15 and the exhaust pipe 19. The flow rate adjuster 212 is disposed in the communicating pipe 211. One end of the communicating pipe 211 is connected to a portion of the intake pipe 15 downstream of the turbocharger 11. Specifically, one end of the communicating pipe 211 is connected to a portion of the intake pipe 15 downstream of the compressor 112. Therefore, compressed air can be effectively supplied to the exhaust pipe 19 through the communicating pipe 211. Furthermore, the flow rate adjuster 212 adjusts the flow rate of air flowing through the communicating pipe 211. Therefore, under conditions in which unburned hydrogen does not flow into the exhaust pipe 19, the flow rate adjuster 212 can block the flow path of the communicating pipe 211 and prohibit air from flowing into the exhaust pipe 19. As a result, according to the first embodiment, exhaust gas is discharged more smoothly from the exhaust pipe 19.

[0028] The other end of the communicating pipe 211 is connected to the exhaust pipe 19 at a position upstream of the turbocharger 11. Specifically, the other end of the communicating pipe 211 is connected to the exhaust pipe 19 at a position upstream of the turbine 111.

[0029] Here, the adjustment of the air flow rate by the flow rate adjuster 212 includes not only increasing or decreasing the flow rate continuously or stepwise, but also setting the flow rate to zero. The flow rate adjuster 212 is only required to be able to at least switch the flow path of the communicating pipe 211 between an open state and a closed state. The flow rate adjuster 212 is, for example, a flow rate adjustment valve or an on-off valve.

[0030] Furthermore, it is preferable that the flow rate adjuster 212 be arranged in the communicating pipe 211 closer to the exhaust pipe 19 than to the air intake pipe 15. This is because, if air from the air intake pipe 15 is present in the communicating pipe 211 close to the exhaust pipe 19 when the flow rate adjuster 212 is closed, the time it takes for the air to be introduced into the exhaust pipe 19 after the flow rate adjuster 212 is opened is shortened. In other words, the responsiveness when the air is introduced into the exhaust pipe 19 by the flow rate adjuster 212 is improved. For example, the flow rate adjuster 212 is arranged in the communicating pipe 211 near the exhaust pipe 19.

[0031] Continuing with reference to Figure 1, the engine 1 will be described. The engine 1 includes a cylinder head 51, a cylinder block 52, an intake valve 53, an exhaust valve 54, a hydrogen fuel supply unit 55, an ignition inducer 56, a piston 58, a connecting rod 59, a crankshaft 60, and an engine speed detection unit 62. It is preferable that the engine 1 further includes a cylinder pressure detection unit 57. The engine 1 also has a combustion chamber 61. The combustion chamber 61 is formed in the cylinder block 52. The combustion chamber 61 is the space between the cylinder head 51 and the piston 58.

[0032] The cylinder head 51 is fixed to the top of the cylinder block 52. The cylinder head 51 has an intake passage 63 and an exhaust passage 64.

[0033] The intake manifold 17 is connected to the inlet of the intake passage 63. Therefore, compressed and cooled air is supplied to the intake passage 63 from the intake manifold 17. The outlet of the intake passage 63 is connected to the combustion chamber 61.

[0034] The hydrogen fuel supply unit 55 is disposed in the cylinder head 51. The hydrogen fuel supply unit 55 supplies hydrogen fuel to the inside of the engine 1. In the example of FIG. 1 , the hydrogen fuel supply unit 55 supplies hydrogen fuel to the intake passage 63. In this case, for example, the hydrogen fuel supply unit 55 injects hydrogen fuel. Therefore, the hydrogen fuel is mixed with air supplied from the intake manifold 17 and supplied to the combustion chamber 61. Specifically, an intake valve 53 is disposed at the outlet of the intake passage 63. The intake valve 53 opens and closes the outlet of the intake passage 63. When the intake valve 53 opens the outlet of the intake passage 63, the hydrogen fuel mixed with air is supplied to the combustion chamber 61. Specifically, as an example, the hydrogen fuel supply unit 55 repeatedly injects hydrogen fuel at regular intervals while the engine 1 is operating. The hydrogen fuel supply unit 55 is, for example, a gas admission valve (GAV) or a gas injector.

[0035] The hydrogen fuel supply unit 55 corresponds to an example of the "gaseous fuel supply unit" of the present invention. For example, the hydrogen fuel supply unit 55 may be disposed in the intake manifold 17, or may be disposed in the intake pipe 15 downstream of the intercooler 13.

[0036] On the other hand, the inlet of the exhaust passage 64 is connected to the combustion chamber 61. The outlet of the exhaust passage 64 is connected to the exhaust pipe 19. Therefore, exhaust gas from the combustion chamber 61 is discharged into the exhaust pipe 19 through the exhaust passage 64. Specifically, an exhaust valve 54 is disposed at the inlet of the exhaust passage 64. The exhaust valve 54 opens and closes the inlet of the exhaust passage 64. When the exhaust valve 54 opens the inlet of the exhaust passage 64, the exhaust gas is discharged into the exhaust pipe 19 through the exhaust passage 64.

[0037] The ignition induction unit 56 induces ignition of hydrogen fuel in the combustion chamber 61. Specifically, the ignition induction unit 56 injects liquid fuel into the combustion chamber 61 to induce ignition of the hydrogen fuel in the combustion chamber 61. The liquid fuel is, for example, light oil or heavy oil. The ignition induction unit 56 is, for example, a liquid fuel injector. The liquid fuel injector is, for example, a pilot fuel injection valve. The ignition induction unit 56 may also be, for example, an "ignition plug" that performs ignition using a spark or a laser.

[0038] The cylinder block 52 constitutes the cylinder 1a. The cylinder block 52 accommodates a piston 58, a connecting rod 59, and a crankshaft 60. The piston 58 reciprocates up and down inside the cylinder block 52. The connecting rod 59 connects the piston 58 to the crankshaft 60. The connecting rod 59 transmits the reciprocating motion of the piston 58 to the crankshaft 60. The crankshaft 60 converts the reciprocating motion of the piston 58 into rotational motion. The crankshaft 60 transmits the rotational motion to the generator 27 via a transmission mechanism (not shown). As a result, a power generating body (e.g., a magnet) of the generator 27 rotates, causing the generator 27 to generate electricity.

[0039] For example, when the piston 58 descends and the intake valve 53 opens with the exhaust valve 54 closed, hydrogen fuel mixed with air is supplied from the intake passage 63 to the combustion chamber 61. Next, the piston 58 ascends with the exhaust valve 54 and intake valve 53 closed. Next, at the top dead center of the piston 58, the ignition inducer 56 injects liquid fuel, which ignites and burns. As a result, the piston 58 descends due to combustion. Next, the piston 58 ascends and the exhaust valve 54 opens with the intake valve 53 closed. As a result, exhaust gas is discharged from the combustion chamber 61 to the exhaust passage 64.

[0040] The engine speed detection unit 62 detects the number of revolutions per unit time of the engine 1. The engine speed detection unit 62 is, for example, an engine speed sensor. The engine speed sensor may be configured, for example, to include a sensor and a pulse generator, and to generate a pulse signal in accordance with the rotation of the crankshaft 60. Hereinafter, the number of revolutions per unit time of the engine 1 may be referred to as the "number of revolutions of the engine 1." The cylinder pressure detection unit 57 detects the pressure of gas in the combustion chamber 61. The cylinder pressure detection unit 57 is, for example, a pressure sensor.

[0041] Here, factors that cause unburned hydrogen to flow into the exhaust pipe 19 will be exemplified.

[0042] For example, if the generator load on the generator 27 suddenly decreases, unburned hydrogen will be generated in the combustion chamber 61 and flow into the exhaust pipe 19. The reason for this is as follows: When the generator load decreases, the engine 1 is not required to maintain the output power before the generator load decrease. Therefore, control is executed to reduce the output power of the engine 1. Specifically, the hydrogen flow rate regulator 7 and / or the hydrogen fuel supply unit 55 are controlled to reduce the amount of hydrogen fuel supplied by the hydrogen fuel supply unit 55. However, the amount of hydrogen fuel supplied does not instantly transition to an amount corresponding to the decreased generator load, but rather, there is a very short period of time during which excess hydrogen fuel is supplied. As a result, if the generator load suddenly decreases, unburned hydrogen will be generated in the combustion chamber 61 and may flow into the exhaust pipe 19. The generator load is generated by a load device driven by the generator 27.

[0043] For example, if the hydrogen fuel supply unit 55 fails, the amount of hydrogen fuel supplied may become excessive, resulting in the generation of unburned hydrogen in the combustion chamber 61. As a result, it can be predicted that the unburned hydrogen will flow into the exhaust pipe 19. In this case, a failure of the hydrogen fuel supply unit 55 indicates, for example, a state in which the hydrogen fuel supply unit 55 remains open and cannot be closed.

[0044] For example, if the ignition inducement unit 56 fails, the liquid fuel for ignition will not be injected. Therefore, there is a possibility that poor ignition of the hydrogen fuel will occur, resulting in the generation of unburned hydrogen in the combustion chamber 61. As a result, it can be predicted that the unburned hydrogen will flow into the exhaust pipe 19. In this case, the failure of the ignition inducement unit 56 indicates, for example, a state in which the ignition inducement unit 56 is unable to inject the liquid fuel.

[0045] In particular, in the first embodiment, in the engine system 100, when it is predicted that unburned hydrogen will flow into the exhaust pipe 19, the gas introducing section 21 is controlled to introduce air into the exhaust pipe 19.

[0046] Next, control of the engine system 100 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the engine system 100. As shown in Fig. 2, the engine system 100 includes a generator control device 29, an operation control device 31, and an engine control device 33.

[0047] The generator control device 29 controls the generator 27. The generator control device 29 includes a power meter 291. The power meter 291 measures the power output by the generator 27. The power output by the generator 27 is supplied to a load device. Therefore, the power output by the generator 27 is an example of information indicating the generator load. The generator control device 29 outputs information indicating the power of the generator 27 measured by the power meter 291 to the engine control device 33.

[0048] The generator control device 29 is, for example, a computer. The computer is, for example, an ECU (Electronic Control Unit). Specifically, the generator control device 29 includes a processor and a storage device. The processor includes, for example, a CPU (Central Processing Unit). The storage device stores data and computer programs. The storage device includes, for example, a main storage device and an auxiliary storage device such as a semiconductor memory. The storage device may include removable media. The generator control device 29 is, for example, a generator control panel.

[0049] The operation control device 31 receives an operation from an operator and outputs an operation signal (hereinafter referred to as "operation signal SG") corresponding to the operation from the operator to the generator control device 29. In this case, the generator control device 29 controls the generator 27 based on the operation signal SG. Specifically, the operation signal SG is a signal for setting the operating state of a load device that receives power supply from the generator 27. Therefore, the operation signal SG is an example of information indicating the generator load.

[0050] The operation control device 31 is, for example, a computer. Specifically, the operation control device 31 includes an input device, a display device, a processor, and a storage device. The input device includes, for example, a keyboard, a pointing device, a dial, and a push button. The display device is, for example, a liquid crystal display. The display device may include, for example, a touch panel. The processor includes, for example, a CPU. The storage device stores data and computer programs. The storage device includes, for example, a main storage device such as a semiconductor memory, and an auxiliary storage device such as a semiconductor memory and a hard disk drive. The storage device may include removable media. The operation control device 31 is, for example, an operation control panel.

[0051] The engine control device 33 controls the engine 1. The engine control device 33 controls, for example, the hydrogen fuel supply unit 55 and the ignition induction unit 56. The engine control device 33 receives information indicating the rotation speed of the engine 1 from the engine rotation speed detection unit 62. The engine control device 33 also receives information indicating the pressure of the gas in the combustion chamber 61 from the cylinder pressure detection unit 57. The engine control device 33 also controls the hydrogen flow rate adjustment unit 7. The engine control device 33 also controls the gas introduction unit 21. Specifically, the engine control device 33 controls the flow rate adjustment unit 212. The engine control device 33 also receives information indicating the temperature of the exhaust gas from the temperature detection unit 23. The engine control device 33 also receives information indicating the pressure of the exhaust gas from the pressure detection unit 25.

[0052] The engine control device 33 is, for example, a computer. The computer is, for example, an ECU. Specifically, the engine control device 33 includes a control unit 331 and a storage unit 332. The control unit 331 includes a processor such as a CPU. The storage unit 332 includes a storage device and stores data and computer programs. The storage device includes, for example, a main storage device and an auxiliary storage device such as a semiconductor memory. The storage device may include removable media.

[0053] The engine control device 33 includes an introduction determination unit A1 and an introduction control unit A2. Specifically, the processor of the engine control device 33 executes a computer program stored in the storage device of the storage unit 332, thereby functioning as the introduction determination unit A1 and the introduction control unit A2.

[0054] The introduction determination unit A1 determines whether or not to introduce air into the exhaust pipe 19 through the gas introduction unit 21 based on index information (hereinafter referred to as "index information IF"). The index information IF is information that serves as an index indicating whether or not hydrogen fuel (unburned hydrogen) that was not burned in the combustion chamber 61 has flowed from the engine 1 into the exhaust pipe 19.

[0055] Then, based on the determination result of the introduction determination unit A1, the introduction control unit A2 controls the gas introduction unit 21 (specifically, the flow rate adjustment unit 212) to introduce air into the exhaust pipe 19. Therefore, the gas introduction unit 21 can introduce air into the exhaust pipe 19 only when the index information IF predicts that unburned hydrogen has flowed into the exhaust pipe 19. As a result, when unburned hydrogen has not flowed into the exhaust pipe 19, air is not introduced into the exhaust pipe 19, and the exhaust gas can be discharged more smoothly.

[0056] For example, if the index information IF indicates that unburned hydrogen has flowed into the exhaust pipe 19, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19. In this case, the introduction control unit A2 controls the gas introduction unit 21 to introduce air into the exhaust pipe 19. As a result, the gas introduction unit 21 introduces air into the exhaust pipe 19. On the other hand, for example, if the index information IF indicates that unburned hydrogen has not flowed into the exhaust pipe 19, the introduction determination unit A1 determines not to introduce air into the exhaust pipe 19. In this case, the introduction control unit A2 controls the gas introduction unit 21 not to introduce air into the exhaust pipe 19. As a result, the gas introduction unit 21 does not introduce air into the exhaust pipe 19.

[0057] Specifically, the index information IF includes engine output information that directly or indirectly indicates the output of the engine 1. Therefore, the introduction determination unit A1 determines, based on the engine output information, whether or not to introduce air into the exhaust pipe 19 by the gas introduction unit 21. As a result, it is possible to more appropriately determine whether or not to introduce air into the exhaust pipe 19.

[0058] For example, in a case where the engine output information directly indicates the output of engine 1, when the output of engine 1 indicated by the engine output information falls below threshold value THA, or when the rate of decrease in the output of engine 1 becomes equal to or greater than threshold value THB, the introduction determination unit A1 decides to introduce air into the exhaust pipe 19 using the gas introduction unit 21. The rate of decrease in the output of engine 1 indicates, for example, when the introduction determination unit A1 acquires information directly indicating the output of engine 1 at a predetermined period, the ratio (=EQ / E0) of the output EQ of engine 1 acquired Q times ago to the latest output E0 of engine 1. "Q" is any integer greater than or equal to 1. "Q times ago" indicates "Q times ago with respect to the latest."

[0059] On the other hand, engine output information (hereinafter referred to as "engine output information ID") that indirectly indicates the output of engine 1 includes, for example, at least one of information indicating the rotation speed of engine 1 and information indicating the generator load, which is the load on generator 27.

[0060] The rotation speed of the engine 1 changes in conjunction with the generator load. For example, if the generator load drops instantaneously, the rotation speed of the engine 1 also increases instantaneously, albeit for a very short time. Therefore, an instantaneous increase in the rotation speed of the engine 1 indicates an instantaneous drop in the generator load. Therefore, if the rotation speed of the engine 1 increases instantaneously, it can be predicted that unburned hydrogen will flow into the exhaust pipe 19. Therefore, the introduction determination unit A1 acquires information indicating the rotation speed of the engine 1 from the engine rotation speed detection unit 62 and determines whether or not to introduce air into the exhaust pipe 19 using the gas introduction unit 21, based on the rotation speed of the engine 1. In other words, according to the first embodiment, the introduction determination unit A1 can easily determine whether or not to introduce air into the exhaust pipe 19, based on the rotation speed of the engine 1.

[0061] Specifically, the introduction determination unit A1 determines whether or not to introduce air into the exhaust pipe 19 based on the degree of increase in the rotation speed of the engine 1. Therefore, according to the first embodiment, when unburned hydrogen flows into the exhaust pipe 19 due to a decrease in the generator load, it is possible to determine to introduce air into the exhaust pipe 19.

[0062] For example, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19 when the rotation speed of the engine 1 becomes equal to or greater than a threshold value TH1. Alternatively, for example, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19 when the rate of increase in the rotation speed of the engine 1 becomes equal to or greater than a threshold value TH2. The rate of increase in the rotation speed of the engine 1 indicates, for example, the ratio (=N0 / NM) of the latest rotation speed NO to the rotation speed NM acquired M times ago when the introduction determination unit A1 acquires information on the rotation speed of the engine 1 from the engine rotation speed detection unit 62 at a predetermined cycle. "M" is any integer greater than or equal to 1. "M times ago" indicates "M times ago with respect to the latest."

[0063] Alternatively, the introduction determination unit A1 may directly acquire information indicating the generator load and determine, based on the generator load, whether or not to introduce air into the exhaust pipe 19 by the gas introduction unit 21. In this case, by directly acquiring the information indicating the generator load, the introduction determination unit A1 can more accurately determine whether or not to introduce air into the exhaust pipe 19.

[0064] Specifically, the introduction determination unit A1 determines, based on the degree of reduction in the generator load, whether or not to introduce air into the exhaust pipe 19. Therefore, according to the first embodiment, when unburned hydrogen flows into the exhaust pipe 19 due to a reduction in the generator load, it is possible to determine to introduce air into the exhaust pipe 19.

[0065] For example, the introduction determination unit A1 acquires information indicating the power of the generator 27 as information indicating the generator load from the power meter 291 of the generator control device 29. Then, the introduction determination unit A1 determines whether or not to introduce air into the exhaust pipe 19 based on the value of the power of the generator 27.

[0066] In this case, for example, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19 when the power of the generator 27 becomes equal to or lower than a threshold value TH3. Alternatively, for example, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19 when the rate of decrease in the power of the generator 27 becomes equal to or higher than a threshold value TH4. The rate of decrease in the generator load indicates, for example, when the introduction determination unit A1 acquires power information from the power meter 291 at a predetermined interval, the ratio of the power value PK acquired K times ago to the most recent power value P0 (=PK / P0). "K" is any integer greater than or equal to 1. "K times ago" indicates "K times ago with respect to the most recent."

[0067] Alternatively, for example, the introduction determination unit A1 obtains the operation signal SG directly from the operation control device 31 as information indicating the generator load, or obtains the operation signal SG indirectly via the generator control device 29. The operation signal SG is a signal for setting the operating state of the load device receiving power from the generator 27. In this case, the "operating state" is indicated by the level of the generator load. Therefore, the operation signal SG indicates the level of the generator load. Therefore, the introduction determination unit A1 determines whether to introduce air into the exhaust pipe 19 based on the level of the generator load indicated by the operation signal SG.

[0068] In this case, for example, when the level of the generator load indicated by the operation signal SG becomes equal to or lower than a threshold value TH5, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19. Alternatively, for example, when the rate of decrease in the generator load indicated by the operation signal SG becomes equal to or higher than a threshold value TH6, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19. The rate of decrease in the generator load indicates, for example, the ratio (=L1 / L0) of the generator load level L1 set by the previous operation signal SG to the generator load level L0 set by the latest operation signal SG.

[0069] Furthermore, the index information IF may include information indicating the state of the hydrogen fuel supply unit 55. Therefore, the introduction determination unit A1 determines whether or not to introduce air into the exhaust pipe 19 by the gas introduction unit 21 based on the state of the hydrogen fuel supply unit 55. As a result, whether or not to introduce air into the exhaust pipe 19 can be determined from the perspective of the state of the hydrogen fuel supply unit 55.

[0070] For example, the introduction determination unit A1 determines whether the hydrogen fuel supply unit 55 has failed. If it is determined that the hydrogen fuel supply unit 55 has failed, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19. This is because, as described above, if the hydrogen fuel supply unit 55 fails, an excessive amount of hydrogen fuel may be supplied, which may result in unburned hydrogen being generated in the combustion chamber 61. In this case, specifically, the state of the hydrogen fuel supply unit 55 is indicated by the pressure of gas in the combustion chamber 61 of the engine 1. Therefore, the introduction determination unit A1 obtains information indicating the pressure of gas in the combustion chamber 61 from the cylinder pressure detection unit 57. Then, the introduction determination unit A1 determines whether to introduce air into the exhaust pipe 19 based on the pressure of gas in the combustion chamber 61.

[0071] The reason why the pressure of the gas in the combustion chamber 61 indicates the state of the hydrogen fuel supply unit 55 is as follows. That is, if the hydrogen fuel supply unit 55 malfunctions and the amount of hydrogen fuel supplied becomes excessive, the pressure of the gas in the combustion chamber 61 rises. Therefore, by monitoring the pressure of the gas in the combustion chamber 61, it can be determined whether or not the hydrogen fuel supply unit 55 has malfunctioned. Therefore, the introduction determination unit A1 determines whether or not the pressure of the gas in the combustion chamber 61 is equal to or greater than the threshold value TH7. Then, if it is determined that the pressure of the gas in the combustion chamber 61 is equal to or greater than the threshold value TH7, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19.

[0072] Furthermore, the index information IF may include information indicating the state of the ignition induction unit 56. Therefore, the introduction determination unit A1 determines whether or not to introduce air into the exhaust pipe 19 by the gas introduction unit 21, based on the state of the ignition induction unit 56. As a result, whether or not to introduce air into the exhaust pipe 19 can be determined from the perspective of the state of the ignition induction unit 56.

[0073] For example, the introduction determination unit A1 determines whether the ignition induction unit 56 has failed. If it is determined that the ignition induction unit 56 has failed, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19. This is because, as described above, if the ignition induction unit 56 fails, poor ignition of the hydrogen fuel may occur, resulting in the generation of unburned hydrogen in the combustion chamber 61. In this case, specifically, the state of the ignition induction unit 56 is indicated by the pressure of the gas in the combustion chamber 61 of the engine 1. Therefore, the introduction determination unit A1 obtains information indicating the pressure of the gas in the combustion chamber 61 from the cylinder pressure detection unit 57. Then, the introduction determination unit A1 determines whether to introduce air into the exhaust pipe 19 based on the pressure of the gas in the combustion chamber 61.

[0074] The reason why the pressure of the gas in the combustion chamber 61 indicates the state of the ignition inducement unit 56 is as follows. That is, if the ignition inducement unit 56 fails and poor ignition of the hydrogen fuel occurs, the pressure of the gas in the combustion chamber 61 will be abnormally low. Therefore, by monitoring the pressure of the gas in the combustion chamber 61, it is possible to determine whether the ignition inducement unit 56 has failed. Therefore, the introduction determination unit A1 determines whether the pressure of the gas in the combustion chamber 61 is equal to or lower than the threshold value TH8. If it is determined that the pressure of the gas in the combustion chamber 61 is equal to or lower than the threshold value TH8, the introduction determination unit A1 determines to introduce air into the exhaust pipe 19. Note that the threshold value TH8 used to determine whether the ignition inducement unit 56 has failed is lower than the threshold value TH7 used to determine whether the hydrogen fuel supply unit 55 has failed.

[0075] Next, changes in the state of the engine system 100 will be described with reference to Figure 3. Figure 3 is a time chart showing changes in various states of the engine system 100. In Figure 3, the horizontal axes of charts CT1 to CT6 represent time. The vertical axis of chart CT1 represents the generator load, the vertical axis of chart CT2 represents the rotation speed of the engine 1, and the vertical axis of chart CT3 represents the injection amount (supply amount) of hydrogen fuel by the hydrogen fuel supply unit 55. The vertical axis of chart CT4 represents the aperture of the flow rate adjustment unit 212, the vertical axis of chart CT5 represents the concentration of unburned hydrogen in the exhaust pipe 19, and the vertical axis of chart CT6 represents the temperature of the exhaust gas in the exhaust pipe 19. The aperture of the flow rate adjustment unit 212 represents the degree to which the flow rate adjustment unit 212 is open.

[0076] As shown in chart CT1, at time t1, the generator load drops instantaneously. Then, as shown in chart CT2, in response to this drop in the generator load, the rotation speed of engine 1 rises sharply. After that, the rotation speed of engine 1 drops, and at approximately time t2, the rotation speed of engine 1 becomes constant.

[0077] Furthermore, as shown in chart CT3, at time t1, control is executed to reduce the injection amount (supply amount) of hydrogen fuel from the hydrogen fuel supply unit 55 in response to a decrease in the generator load. As a result, the injection amount of hydrogen fuel decreases. Thereafter, the injection amount of hydrogen fuel increases once, before becoming constant at time t2. As can be seen from chart CT3, due to the limit of the responsiveness of the hydrogen fuel supply unit 55, the injection amount of hydrogen fuel does not become constant immediately at the start time t1 of the control to reduce the injection amount, but becomes constant over the period from time t1 to time t2. As a result, unburned hydrogen is generated, and unburned hydrogen flows from the combustion chamber 61 into the exhaust pipe 19.

[0078] Therefore, as shown in chart CT4, at time t1, introduction control unit A2 opens flow rate adjustment unit 212 to open the flow path of connecting pipe 211. Therefore, air from intake pipe 15 is introduced into exhaust pipe 19 through connecting pipe 211. As a result, as shown by solid line C1 in chart CT5, unburned hydrogen in exhaust pipe 19 is diluted with air, and the concentration of unburned hydrogen decreases. As a result, combustion of unburned hydrogen in exhaust pipe 19 is suppressed. In the example of FIG. 3 , flow rate adjustment unit 212 is opened only during period TM from time t1 to time t12, and air is introduced into exhaust pipe 19. Then, at time t12, which is before time t2, introduction control unit A2 closes flow rate adjustment unit 212 to block the flow path of connecting pipe 211. Therefore, air from intake pipe 15 is not introduced into exhaust pipe 19.

[0079] As a reference example, as shown by the dashed line C2 in chart CT5, when air is not introduced into the exhaust pipe 19 at time t1, the unburned hydrogen in the exhaust pipe 19 is not diluted, and the concentration of unburned hydrogen is relatively high.

[0080] Furthermore, as shown by the solid line T1 in chart CT6, at time t1, air is introduced into the exhaust pipe 19 from the connecting pipe 211, so the temperature of the exhaust gas in the exhaust pipe 19 drops sharply and then gradually drops again. As a result, unburned hydrogen is further inhibited from burning in the exhaust pipe 19. In particular, the time from when the temperature of the exhaust gas starts to drop until it becomes constant is shorter when air is introduced into the exhaust pipe 19 (solid line T1) than when air is not introduced into the exhaust pipe 19 (dashed line T2).

[0081] As a reference example, as shown by the dashed line T2 in the chart CT6, when no air is introduced into the exhaust pipe 19 at time t1, the temperature of the exhaust gas in the exhaust pipe 19 does not drop abruptly but rather drops gradually.

[0082] Next, a control method for the gas introduction unit 21 will be described with reference to Fig. 2 and Fig. 4. Fig. 4 is a flowchart showing the control method for the gas introduction unit 21. As shown in Fig. 4, the control method includes steps S1 to S6. The control method is executed by the engine control device 33.

[0083] As shown in FIGS. 2 and 4, first, in step S1, the introduction determination unit A1 determines whether a first dilution start condition is satisfied. The first dilution start condition is a condition related to the output of the engine 1 and is a condition for introducing air into the exhaust pipe 19 by the gas introduction unit 21. The first dilution start condition may include at least one of the first to sixth start conditions. The first start condition is that the rotation speed of the engine 1 is equal to or greater than a threshold value TH1. The second start condition is that the rate of increase in the rotation speed of the engine 1 is equal to or greater than a threshold value TH2. The third start condition is that the power of the generator 27 is equal to or less than a threshold value TH3. The fourth start condition is that the rate of decrease in the power of the generator 27 is equal to or greater than a threshold value TH4. The fifth start condition is that the level of the generator load indicated by the operation signal SG is equal to or less than a threshold value TH5. The sixth start condition is that the rate of decrease in the generator load indicated by the operation signal SG is equal to or greater than a threshold value TH6.

[0084] When any one of the one or more start conditions included in the first dilution start condition among the first to sixth start conditions is satisfied, the introduction determination unit A1 determines that the first dilution start condition is satisfied in step S1, and proceeds to step S4. The fact that the introduction determination unit A1 has determined that the first dilution start condition is satisfied corresponds to a decision to introduce air into the exhaust pipe 19 by the gas introduction unit 21.

[0085] On the other hand, if all of the one or more start conditions included in the first dilution start condition among the first to sixth start conditions are not satisfied, the introduction determination unit A1 determines in step S1 that the first dilution start condition is not satisfied, and proceeds to step S2.

[0086] Next, in step S2, the introduction determination unit A1 determines whether a second dilution start condition is satisfied. The second dilution start condition is a condition related to the hydrogen fuel supply unit 55, and is a condition for introducing air into the exhaust pipe 19 by the gas introduction unit 21. The second dilution start condition is that the pressure of the gas in the combustion chamber 61 is equal to or higher than a threshold value TH7.

[0087] If the introduction determination unit A1 determines in step S2 that the second dilution start condition is satisfied, the process proceeds to step S4. The fact that the introduction determination unit A1 determines that the second dilution start condition is satisfied corresponds to a decision to introduce air into the exhaust pipe 19 by the gas introduction unit 21.

[0088] On the other hand, if the introduction determining unit A1 determines in step S2 that the second dilution start condition is not satisfied, the process proceeds to step S3.

[0089] Next, in step S3, the introduction determination unit A1 determines whether a third dilution start condition is satisfied. The third dilution start condition is a condition related to the ignition inducement unit 56, and is a condition for introducing air into the exhaust pipe 19 by the gas introduction unit 21. The third dilution start condition is that the pressure of the gas in the combustion chamber 61 is equal to or lower than a threshold value TH8.

[0090] If the introduction determination unit A1 determines in step S3 that the third dilution start condition is satisfied, the process proceeds to step S4. The fact that the introduction determination unit A1 determines that the third dilution start condition is satisfied corresponds to a determination that air is to be introduced into the exhaust pipe 19 by the gas introduction unit 21.

[0091] On the other hand, if the introduction determining unit A1 determines in step S3 that the third dilution start condition is not satisfied, the process ends.

[0092] After it is determined in step S1 that the first dilution start condition is satisfied, after it is determined in step S2 that the second dilution start condition is satisfied, or after it is determined in step S3 that the third dilution start condition is satisfied, in step S4, the introduction control unit A2 opens the flow path of the communicating pipe 211 using the flow rate adjustment unit 212 to start introducing air from the air intake pipe 15 and the communicating pipe 211 into the exhaust pipe 19. In this case, the introduction control unit A2 sets the opening degree of the flow rate adjustment unit 212 to a predetermined opening degree. In the first embodiment, the predetermined opening degree is a fixed value. The predetermined opening degree indicates, for example, full opening.

[0093] Next, in step S5, the introduction control unit A2 determines whether a predetermined open time has elapsed since the flow rate adjustment unit 212 opened the flow path of the communicating pipe 211. The predetermined open time is the time for which the flow path of the communicating pipe 211 is kept open (the time for introducing air into the exhaust pipe 19), and is determined in advance. In other words, the predetermined open time is the open time of the flow rate adjustment unit 212. In the first embodiment, the predetermined open time is a fixed value. For example, the predetermined open time is set to the time when the concentration of unburned hydrogen becomes less than the ignition concentration when the largest possible amount of unburned hydrogen flows into the exhaust pipe 19. The ignition concentration is preferably, for example, a value of 4% or less. This is because hydrogen will not ignite if the hydrogen concentration in the air is less than 4%.

[0094] If it is determined in step S5 that the predetermined open time has not elapsed, step S5 is executed until the predetermined open time has elapsed.

[0095] On the other hand, if it is determined in step S5 that the predetermined open time has elapsed, the process proceeds to step S6.

[0096] Next, in step S6, the introduction control unit A2 closes the flow path of the communicating pipe 211 using the flow rate adjusting unit 212 to stop the introduction of air from the air intake pipe 15 and the communicating pipe 211 to the exhaust pipe 19. In other words, the introduction control unit A2 closes the flow rate adjusting unit 212. Then, the process ends.

[0097] (First Modification) A first modified example of the first embodiment of the present invention will be described with reference to Figures 1, 2, and 5. The first modified example is mainly different from the first embodiment described with reference to Figure 4 in that the opening degree and opening time of the flow rate adjuster 212 that introduces air into the exhaust pipe 19 are dynamically set. Below, the differences between the first modified example and the first embodiment will be mainly described.

[0098] First, control of the opening degree of the flow rate adjustment unit 212 will be described with reference to FIGS. 1 and 2. The introduction control unit A2 controls the flow rate of air introduced into the exhaust pipe 19 by the gas introduction unit 21 based on at least one of the degree of increase in the rotation speed of the engine 1, the degree of decrease in the generator load, the temperature of the exhaust gas upstream of the turbocharger 11 (specifically, the turbine 111) inside the exhaust pipe 19, and the pressure of the exhaust gas upstream of the turbocharger 11 (specifically, the turbine 111) inside the exhaust pipe 19. In other words, the introduction control unit A2 controls the opening degree of the flow rate adjustment unit 212 based on at least one of the degree of increase in the rotation speed of the engine 1, the degree of decrease in the generator load, the temperature of the exhaust gas, and the pressure of the exhaust gas. This is because the flow rate of air introduced into the exhaust pipe 19 is determined by the opening degree of the flow rate adjustment unit 212. The flow rate of air introduced into the exhaust pipe 19, i.e., the opening degree of the flow rate adjustment unit 212, is dynamically controlled and is not a fixed value.

[0099] When the opening degree of the flow rate adjustment unit 212 is controlled based on the degree of increase in the rotation speed of the engine 1 or the degree of decrease in the generator load, the opening degree of the flow rate adjustment unit 212 can be set according to the amount of unburned hydrogen that flows into the exhaust pipe 19. For example, the introduction control unit A2 sets the opening degree of the flow rate adjustment unit 212 to be greater the greater the degree of increase in the rotation speed of the engine 1 (e.g., the rate of increase). This is because the greater the degree of increase in the rotation speed of the engine 1, the greater the amount of unburned hydrogen that may flow into the exhaust pipe 19. For example, the introduction control unit A2 sets the opening degree of the flow rate adjustment unit 212 to be greater the greater the degree of decrease in the generator load (e.g., the rate of decrease). This is because the greater the degree of decrease in the generator load, the greater the amount of unburned hydrogen that may flow into the exhaust pipe 19.

[0100] Furthermore, for example, the higher the temperature of the exhaust gas upstream of the turbocharger 11 inside the exhaust pipe 19, the greater the opening of the flow rate adjuster 212 is set by the introduction control unit A2 to increase the flow rate of air introduced into the exhaust pipe 19. The reason for this is as follows: the higher the temperature of the exhaust gas, the greater the possibility that unburned hydrogen will ignite. Therefore, by increasing the flow rate of air introduced into the exhaust pipe 19, the temperature and concentration of unburned hydrogen can be more effectively reduced. As a result, the combustion of unburned hydrogen can be effectively suppressed. In this example, the introduction control unit A2 obtains information indicating the temperature of the exhaust gas from the temperature detection unit 23.

[0101] Furthermore, for example, the higher the exhaust gas pressure upstream of the turbocharger 11 inside the exhaust pipe 19, the larger the opening of the flow rate adjustment unit 212 set by the introduction control unit A2 to increase the flow rate of air introduced into the exhaust pipe 19. The reason for this is as follows: the higher the exhaust gas pressure, the more difficult it is for air to flow into the exhaust pipe 19. Therefore, by increasing the opening of the flow rate adjustment unit 212, air can be more reliably introduced into the exhaust pipe 19. As a result, it is possible to effectively suppress the combustion of unburned hydrogen. In this example, the introduction control unit A2 obtains information indicating the exhaust gas pressure from the pressure detection unit 25.

[0102] 1 and 2, the control of the open time of the flow rate adjustment unit 212 will be described. The introduction control unit A2 controls the introduction time of air introduced into the exhaust pipe 19 by the gas introduction unit 21 based on at least one of the degree of increase in the rotation speed of the engine 1, the degree of decrease in the generator load, the temperature of the exhaust gas upstream of the turbocharger 11 (specifically, the turbine 111) inside the exhaust pipe 19, and the pressure of the exhaust gas upstream of the turbocharger 11 (specifically, the turbine 111) inside the exhaust pipe 19. The introduction time of air indicates the open time during which the flow rate adjustment unit 212 keeps the flow path of the communicating pipe 211 open. In other words, the introduction time of air indicates the open time of the flow rate adjustment unit 212. The introduction time of air is not a fixed value because it is dynamically changed.

[0103] When the air introduction time is controlled based on the degree of increase in the rotation speed of the engine 1 or the degree of decrease in the generator load, the air introduction time can be set according to the amount of unburned hydrogen flowing into the exhaust pipe 19. For example, the introduction control unit A2 sets the air introduction time longer the greater the degree of increase in the rotation speed of the engine 1 (e.g., increase rate). This is because the greater the degree of increase in the rotation speed of the engine 1, the greater the possibility of an increase in the amount of unburned hydrogen flowing into the exhaust pipe 19. For example, the introduction control unit A2 sets the air introduction time longer the greater the degree of decrease in the generator load (e.g., decrease rate). This is because the greater the degree of decrease in the generator load, the greater the possibility of an increase in the amount of unburned hydrogen flowing into the exhaust pipe 19.

[0104] Furthermore, for example, the introduction control unit A2 sets a longer air introduction time as the exhaust gas temperature increases, thereby increasing the flow rate of air introduced into the exhaust pipe 19. The reason for this is the same as when the opening of the flow rate adjustment unit 212 increases as the exhaust gas temperature increases. In this example, the introduction control unit A2 obtains information indicating the exhaust gas temperature from the temperature detection unit 23.

[0105] Furthermore, for example, the introduction control unit A2 sets the air introduction time longer as the exhaust gas pressure increases. The reason is as follows: the higher the exhaust gas pressure, the more difficult it is for air to flow into the exhaust pipe 19. Therefore, by lengthening the time for introducing air into the exhaust pipe 19, air can be introduced into the exhaust pipe 19 more reliably. As a result, the combustion of unburned hydrogen can be effectively suppressed. In this example, the introduction control unit A2 obtains information indicating the exhaust gas pressure from the pressure detection unit 25.

[0106] Next, a control method for the gas introduction part 21 will be described with reference to Fig. 2 and Fig. 5. Fig. 5 is a flowchart showing a control method for the gas introduction part 21 according to a first modified example. As shown in Fig. 5, the control method includes steps S11 to S18. The control method is executed by the engine control device 33.

[0107] 2 and 5, the introduction determining unit A1 executes steps S11 to S13, which are the same as steps S1 to S3 shown in FIG.

[0108] After it is determined in step S11 that the first dilution start condition is satisfied, after it is determined in step S12 that the second dilution start condition is satisfied, or after it is determined in step S13 that the third dilution start condition is satisfied, in step S14 the introduction control unit A2 determines the opening degree of the flow rate adjustment unit 212, i.e., the flow rate of air introduced into the exhaust pipe 19, based on at least one of the degree of increase in engine speed 1, the degree of decrease in generator load, the exhaust gas temperature, and the exhaust gas pressure.

[0109] Next, in step S15, the introduction control unit A2 determines the opening time of the flow rate adjustment unit 212, i.e., the introduction time of air into the exhaust pipe 19, based on at least one of the degree of increase in engine speed 1, the degree of decrease in generator load, the temperature of the exhaust gas, and the pressure of the exhaust gas.

[0110] Next, in step S16, the introduction control unit A2 opens the flow path of the communication pipe 211 using the flow rate adjustment unit 212, and starts introducing air from the air intake pipe 15 and the communication pipe 211 into the exhaust pipe 19. In this case, the introduction control unit A2 sets the opening degree of the flow rate adjustment unit 212 to the opening degree determined in step S14.

[0111] Next, in step S17, the introduction control unit A2 determines whether or not the open time has elapsed since the flow rate adjustment unit 212 opened the flow path of the communicating pipe 211. The open time is the time during which the flow path of the communicating pipe 211 is kept open (the time during which air is introduced into the exhaust pipe 19), and is the time determined in step S15.

[0112] If it is determined in step S17 that the open time has not elapsed, step S17 is executed until the open time has elapsed.

[0113] On the other hand, if it is determined in step S17 that the open time has elapsed, the process proceeds to step S18.

[0114] Next, in step S18, the introduction control unit A2 closes the flow path of the communicating pipe 211 using the flow rate adjusting unit 212 to stop the introduction of air from the air intake pipe 15 and the communicating pipe 211 to the exhaust pipe 19. In other words, the introduction control unit A2 closes the flow rate adjusting unit 212. Then, the process ends.

[0115] The introduction control unit A2 may not execute step S14. In this case, the opening degree of the flow rate adjustment unit 212 is set in advance in the same manner as in the first embodiment described with reference to Fig. 4. Alternatively, the introduction control unit A2 may not execute step S15. In this case, the opening time of the flow rate adjustment unit 212 is set to a predetermined opening time in the same manner as in the first embodiment described with reference to Fig. 4.

[0116] (Second Modification) A second modified example of the first embodiment of the present invention will be described with reference to Figures 1, 2, and 6. The second modified example differs from the first embodiment described with reference to Figure 4 mainly in that the conditions for stopping the air introduced into the exhaust pipe 19 are determined by the rotation speed of the engine 1. Below, the differences between the second modified example and the first embodiment will be mainly described.

[0117] First, the second modified example will be described with reference to Figures 1 and 2. The introduction control unit A2 stops the introduction of air into the exhaust pipe 19 by the gas introduction unit 21 based on the degree of reduction in the rotation speed of the engine 1. Therefore, the introduction of air into the exhaust pipe 19 can be stopped when the unburned hydrogen in the exhaust pipe 19 has been sufficiently diluted.

[0118] For example, when the rotation speed of the engine 1 becomes equal to or less than a threshold value TH9, the introduction control unit A2 closes the flow rate adjustment unit 212 to stop the introduction of air into the exhaust pipe 19. Alternatively, for example, when the rate of decrease of the rotation speed of the engine 1 becomes equal to or less than a threshold value TH10, the introduction control unit A2 closes the flow rate adjustment unit 212 to stop the introduction of air into the exhaust pipe 19. The rate of decrease of the rotation speed of the engine 1 indicates, for example, the ratio (=NM / N0) of the rotation speed NM acquired M times ago to the latest rotation speed N0 when the introduction determination unit A1 acquires information on the rotation speed of the engine 1 from the engine rotation speed detection unit 62 at a predetermined cycle. "M" is any integer equal to or greater than 1.

[0119] Next, a control method for the gas introduction part 21 will be described with reference to Fig. 2 and Fig. 6. Fig. 6 is a flowchart showing a control method for the gas introduction part 21 according to a second modified example. As shown in Fig. 6, the control method includes steps S21 to S26. The control method is executed by the engine control device 33.

[0120] 2 and 6, the introduction determining unit A1 executes steps S21 to S23, which are the same as steps S1 to S3 shown in FIG.

[0121] Next, the introduction control unit A2 executes step S24, which is the same as step S4 described with reference to FIG.

[0122] Next, in step S25, the introduction control unit A2 determines whether the dilution stop condition is satisfied. The dilution stop condition is a condition for stopping the introduction of air into the exhaust pipe 19 by the gas introduction unit 21. The dilution stop condition may include at least one of a first stop condition and a second stop condition. The first stop condition is that the rotation speed of the engine 1 is equal to or less than a threshold value TH9. The second stop condition is that the rate of decrease of the rotation speed of the engine 1 is equal to or less than a threshold value TH10.

[0123] If all of the one or more stop conditions included in the dilution stop condition among the first stop condition and the second stop condition are not satisfied, the introduction control unit A2 executes step S25 until all of the one or more stop conditions are satisfied.

[0124] On the other hand, if any one of the one or more stop conditions included in the dilution stop condition among the first stop condition and the second stop condition is satisfied, the introduction control unit A2 determines in step S25 that the dilution stop condition is satisfied, and proceeds to step S26. The fact that the introduction control unit A2 has determined that the dilution stop condition is satisfied corresponds to a decision to stop the introduction of air into the exhaust pipe 19.

[0125] Next, in step S26, the introduction control unit A2 closes the flow path of the communicating pipe 211 using the flow rate adjusting unit 212 to stop the introduction of air from the air intake pipe 15 and the communicating pipe 211 to the exhaust pipe 19. In other words, the introduction control unit A2 closes the flow rate adjusting unit 212. Then, the process ends.

[0126] (Third Modification) A third modified example of the first embodiment of the present invention will be described with reference to Figures 1, 2, and 7. The third modified example differs mainly from the second modified example described with reference to Figure 6 in that the opening degree of the flow rate adjuster 212 that introduces air into the exhaust pipe 19 is dynamically set. Below, the differences between the third modified example and the second modified example will be mainly described.

[0127] 7 is a flowchart showing a control method for the gas introduction part 21 according to the third modified example. As shown in FIG. 7, the control method includes steps S31 to S37. The control method is executed by the engine control device 33.

[0128] 2 and 7, the introduction determining unit A1 executes steps S31 to S33, which are the same as steps S21 to S23 shown in FIG.

[0129] Next, the introduction control unit A2 executes steps S34 and S35. Steps S34 and S35 are similar to steps S14 and S16, respectively, described with reference to FIG.

[0130] Next, the introduction control unit A2 executes steps S36 and S37. Steps S36 and S37 are respectively similar to steps S25 and S26 described with reference to FIG.

[0131] (Embodiment 2) An engine system 100A according to a second embodiment of the present invention will be described with reference to Figures 2 and 8. The second embodiment differs from the first embodiment mainly in that air or an inert gas is introduced into the exhaust pipe 19 from a pressurized gas supply device 35. The following mainly describes the differences between the second embodiment and the first embodiment.

[0132] 8 is a diagram showing the configuration of an engine system 100A according to embodiment 2. As shown in FIG. 8, the engine system 100A includes a gas introduction part 21A instead of the gas introduction part 21 shown in FIG.

[0133] The gas introduction section 21A introduces air or an inert gas into the exhaust pipe 19. Therefore, even if unburned hydrogen that has not been burned by the engine 1 flows into the exhaust pipe 19, the unburned hydrogen that has flowed from the engine 1 into the exhaust pipe 19 can be diluted with the air or inert gas. This makes it possible to reduce the concentration of unburned hydrogen that has flowed into the exhaust pipe 19. As a result, according to the second embodiment, it is possible to suppress the combustion of unburned hydrogen in the exhaust pipe 19. Furthermore, the temperature of the unburned hydrogen that has flowed into the exhaust pipe 19 is lowered by the air or inert gas introduced into the exhaust pipe 19. As a result, it becomes more difficult for the unburned hydrogen to ignite, which further suppresses the combustion of unburned hydrogen in the exhaust pipe 19.

[0134] In this specification, an inert gas is, for example, nitrogen, argon, helium, or carbon dioxide.

[0135] Specifically, gas introduction section 21A is connected to pressurized gas supply device 35 that supplies air or inert gas at a pressure higher than atmospheric pressure, and introduces the air or inert gas into exhaust pipe 19. That is, in embodiment 2, by sending air or inert gas at a pressure higher than atmospheric pressure to exhaust pipe 19, air can be more reliably introduced into exhaust pipe 19 against the pressure of the exhaust gas. Therefore, the concentration of unburned hydrogen that has flowed into exhaust pipe 19 can be more reliably reduced. As a result, combustion of unburned hydrogen in exhaust pipe 19 can be more reliably suppressed.

[0136] The pressurized gas supply device 35 is, for example, a pressurized air tank that stores pressurized air, a pressurized inert gas tank that stores pressurized inert gas, a compressor that pressurizes air and supplies it to the gas introduction part 21A, or a compressor that pressurizes inert gas and supplies it to the gas introduction part 21A.

[0137] More specifically, the gas introduction section 21A includes a pressurized gas introduction pipe 211A and a flow rate adjustment section 212A.

[0138] The pressurized gas introduction pipe 211A guides air or inert gas supplied by the pressurized gas supply device 35 to the exhaust pipe 19. One end of the pressurized gas introduction pipe 211A is connected to the pressurized gas supply device 35. The other end of the pressurized gas introduction pipe 211A is connected to a position upstream of the turbocharger 11 in the exhaust pipe 19. Specifically, the other end of the pressurized gas introduction pipe 211A is connected to a position upstream of the turbine 111 in the exhaust pipe 19.

[0139] The flow rate adjuster 212A is disposed in the pressurized gas introduction pipe 211A. The flow rate adjuster 212A adjusts the flow rate of air or inert gas flowing through the pressurized gas introduction pipe 211A. Therefore, under circumstances in which unburned hydrogen does not flow into the exhaust pipe 19, the flow rate adjuster 212A can block the flow path of the pressurized gas introduction pipe 211A and prevent air or inert gas from flowing into the exhaust pipe 19. As a result, according to the second embodiment, exhaust gas is discharged more smoothly from the exhaust pipe 19.

[0140] Here, the adjustment of the air flow rate by the flow rate adjuster 212A includes not only increasing or decreasing the flow rate continuously or stepwise, but also setting the flow rate to zero. The flow rate adjuster 212A is only required to be able to switch the flow path of the pressurized gas introduction pipe 211A between an open state and a closed state. The flow rate adjuster 212A is, for example, a flow rate adjustment valve or an on-off valve.

[0141] Furthermore, it is preferable that the flow rate adjuster 212A be disposed in the pressurized gas introduction pipe 211A near the exhaust pipe 19. This is because, if the air or inert gas from the pressurized gas supply device 35 is present in the pressurized gas introduction pipe 211A up to the vicinity of the exhaust pipe 19 in a state in which the flow rate adjuster 212A is closed, the time from when the flow rate adjuster 212A is opened until the air is introduced into the exhaust pipe 19 becomes shorter. In other words, the responsiveness when the air or inert gas is introduced into the exhaust pipe 19 by the flow rate adjuster 212A is improved.

[0142] The temperature detection unit 23 detects the temperature of the exhaust gas in the exhaust pipe 19, upstream of the turbine 111 and downstream of the connection point between the pressurized gas introduction pipe 211A and the exhaust pipe 19. The pressure detection unit 25 detects the pressure of the exhaust gas in the exhaust pipe 19, upstream of the turbine 111 and downstream of the connection point between the pressurized gas introduction pipe 211A and the exhaust pipe 19.

[0143] Here, a modification similar to the first modification of the first embodiment can be applied to the second embodiment as well. That is, in the second embodiment, the opening degree and opening time of the flow rate adjustment unit 212A that introduces air or an inert gas into the exhaust pipe 19 can be dynamically set. Furthermore, a modification similar to the second modification of the first embodiment can be applied to the second embodiment as well. That is, in the second embodiment, the stop condition for introducing air into the exhaust pipe 19 can be determined based on the rotation speed of the engine 1. Furthermore, a modification similar to the third modification of the first embodiment can be applied to the second embodiment as well. That is, in the second embodiment, the stop condition for introducing air into the exhaust pipe 19 can be determined based on the rotation speed of the engine 1, and the opening degree of the flow rate adjustment unit 212A that introduces air into the exhaust pipe 19 can be dynamically set.

[0144] Moreover, the control method described with reference to FIGS. 4 to 7 can also be applied to the second embodiment.

[0145] 2, the operation of the introduction determination unit A1 and the introduction control unit A2 in the engine system 100A is the same as the operation of the introduction determination unit A1 and the introduction control unit A2 in the engine system 100. However, the engine system 100A differs from the engine system 100 in that the gas introduced into the exhaust pipe 19 is air or an inert gas, in that the gas introduced into the exhaust pipe 19 in the engine system 100 is air. Therefore, in the explanation of the introduction determination unit A1 and the introduction control unit A2 of the engine system 100 in the first embodiment and the first to third modifications, by replacing "air" with "air or an inert gas," "gas introduction unit 21" with "gas introduction unit 21A," "communicating pipe 211" with "pressurized gas introduction pipe 211A," and "flow rate adjustment unit 212" with "flow rate adjustment unit 212A," the explanation can be applied to the explanation of the second embodiment.

[0146] For example, in the second embodiment, the introduction determination unit A1 determines whether or not to introduce air or an inert gas into the exhaust pipe 19 based on index information IF, which is an index indicating whether or not unburned gas fuel has flowed from the engine 1 into the exhaust pipe 19. Furthermore, the introduction control unit A2 controls the gas introduction unit 21A to introduce air or an inert gas into the exhaust pipe 19 based on the determination result of the introduction determination unit A1.

[0147] For example, in the second embodiment, the introduction determining unit A1 determines whether to introduce air or an inert gas into the exhaust pipe 19 based on the degree of increase in the rotation speed of the engine 1 or the degree of decrease in the generator load.

[0148] For example, in embodiment 2, the introduction control unit A2 controls the introduction time of air or inert gas introduced into the exhaust pipe 19 by the gas introduction unit 21A based on at least one of the degree of increase in engine speed 1, the degree of decrease in generator load, the degree of decrease in engine load, the temperature of the exhaust gas inside the exhaust pipe 19, and the pressure of the exhaust gas inside the exhaust pipe 19.

[0149] For example, in the second embodiment, the introduction control unit A2 stops the introduction of air or inert gas into the exhaust pipe 19 by the gas introduction unit 21A based on the degree of reduction in the rotation speed of the engine 1.

[0150] For example, in embodiment 2, the introduction control unit A2 controls the flow rate of air or inert gas introduced into the exhaust pipe 19 by the gas introduction unit 21A based on at least one of the degree of increase in engine speed 1, the degree of decrease in generator load, the degree of decrease in engine load, the temperature of the exhaust gas inside the exhaust pipe 19, and the pressure of the exhaust gas inside the exhaust pipe 19.

[0151] The embodiments and examples of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit of the present invention. Furthermore, the components disclosed in the above embodiments can be modified as appropriate. For example, some of the components shown in one embodiment may be added to the components of another embodiment, or some of the components shown in one embodiment may be deleted from the embodiment.

[0152] Furthermore, the drawings mainly show each component in a schematic manner to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. Furthermore, the configuration of each component shown in the above embodiment is merely an example and is not particularly limited, and it goes without saying that various modifications are possible within a range that does not substantially deviate from the effects of the present invention.

[0153] (1) In the first embodiment, the first to third modified embodiments, and the second embodiment (hereinafter referred to as "first embodiment, etc.") described with reference to FIGS. 1 to 8, the engine 1 supplies power to the generator 27. However, in the first embodiment, etc., the engine 1 may supply power to a different type of equipment (hereinafter referred to as "equipment MC") from the generator 27. The equipment MC is a load device for the engine 1. For example, the equipment MC is the rotating shaft of a propeller of the boat 200. In this case, the engine 1 supplies power to the rotating shaft of the propeller to rotate the propeller of the boat 200.

[0154] (2) The engine output information ID used by the introduction determination unit A1 and indirectly indicating the output of the engine 1 may include information indicating the torque of the engine 1. The torque of the engine 1 is measured, for example, by a torque meter provided on the output shaft of the engine 1.

[0155] The torque of the engine 1 changes in conjunction with, for example, the generator load. Therefore, for example, if the generator load drops instantaneously, the torque of the engine 1 also drops instantaneously, albeit for an extremely short period of time. Therefore, an instantaneous drop in the torque of the engine 1 indicates an instantaneous drop in the generator load. Therefore, if the torque of the engine 1 drops instantaneously, it can be predicted that unburned hydrogen will flow into the exhaust pipe 19. Therefore, the introduction determination unit A1 determines whether or not to introduce air into the exhaust pipe 19 using the gas introduction unit 21, based on the torque of the engine 1.

[0156] For example, the introduction determination unit A1 may determine whether to introduce air or an inert gas into the exhaust pipe 19 based on the degree of decrease in the torque of the engine 1.

[0157] For example, the introduction control unit A2 may control the introduction time of air or inert gas introduced into the exhaust pipe 19 by the gas introduction units 21, 21A based on the degree of decrease in torque of the engine 1.

[0158] For example, the introduction control unit A2 may control the flow rate of air or inert gas introduced into the exhaust pipe 19 by the gas introduction units 21, 21A based on the degree of decrease in the torque of the engine 1.

[0159] (3) When the engine 1 supplies power to the equipment MC, the engine output information ID used by the introduction determination unit A1, which indirectly indicates the output of the engine 1, may include information indicating the engine load, which is the load on the engine 1.

[0160] (4) When the engine 1 supplies power to the device MC, the introduction determination unit A1 may determine whether to introduce air or an inert gas into the exhaust pipe 19 based on the degree of reduction in the engine load, which is the load on the engine 1. The engine load is generated by the device MC driven by the engine 1.

[0161] (5) When the engine 1 supplies power to the equipment MC, the introduction control unit A2 may control the introduction time of air or inert gas introduced into the exhaust pipe 19 by the gas introduction units 21, 21A based on the degree of reduction in engine load.

[0162] (6) When the engine 1 supplies power to the device MC, the introduction control unit A2 may control the flow rate of air or inert gas introduced into the exhaust pipe 19 by the gas introduction units 21, 21A based on the degree of reduction in engine load.

[0163] (7) In addition, even when the engine 1 supplies power to the equipment MC, the introduction determination unit A1 and the introduction control unit A2 can operate in the same way as when power is supplied to the generator 27. For example, even when the engine 1 supplies power to the equipment MC, the introduction determination unit A1 and the introduction control unit A2 can use information indicating the rotation speed of the engine 1 or information indicating the torque of the engine 1.

[0164] <Notes on the invention> According to one aspect of the present invention, an engine system includes an engine, an exhaust pipe, and a gas introduction section. The engine generates power by burning gaseous fuel. Exhaust gas discharged from the engine flows through the exhaust pipe. The gas introduction section introduces air or an inert gas into the exhaust pipe. [Industrial Applicability]

[0165] The present invention relates to an engine system and has industrial applicability. [Explanation of symbols]

[0166] 1 engine 11. Turbocharger 15 Air supply pipe 19 Exhaust pipe 21, 21A Gas inlet 35 Pressurized gas supply device 55 Hydrogen fuel supply unit (gaseous fuel supply unit) 56 Ignition inducement part 61 Combustion chamber 100, 100A engine system 211 Communication pipe 211A Pressurized gas introduction pipe 212, 212A flow rate adjustment section A1 Introduction Decision Department A2 Introduction control section

Claims

1. an engine that burns gaseous fuel to generate power; an exhaust pipe through which exhaust gas discharged from the engine flows; a gas introduction section that introduces air or an inert gas into the exhaust pipe; a supercharger, the gas introduction portion is connected to the exhaust pipe upstream of the turbocharger, the supercharger compresses the air flowing through an intake pipe that supplies air to the engine, and causes the air to flow through the intake pipe at a pressure greater than atmospheric pressure; The gas introduction section is a communication pipe that communicates the intake pipe and the exhaust pipe; a flow rate adjusting unit that is disposed in the communication pipe and adjusts the flow rate of the air flowing through the communication pipe, an engine system, wherein one end of the communication pipe is connected to the intake pipe downstream of the turbocharger.

2. An engine that generates power by burning gaseous fuel; an exhaust pipe through which exhaust gas discharged from the engine flows; a gas introduction section that introduces air or an inert gas into the exhaust pipe; a supercharger, the gas introduction portion is connected to the exhaust pipe upstream of the turbocharger, The gas introduction section introduces the air compressed by the turbocharger into the exhaust pipe.

3. an introduction determination unit that determines whether to introduce the air or the inert gas into the exhaust pipe based on index information that is an index indicating whether the unburned gaseous fuel has flowed from the engine into the exhaust pipe; an introduction control unit that controls the gas introduction unit so as to introduce the air or the inert gas into the exhaust pipe based on a determination result of the introduction determination unit; The engine system according to claim 1 or claim 2, further comprising:

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