Engine system

Abstract

To enhance safety of an engine system using ammonia as fuel.SOLUTION: An engine system 1 includes an engine 2 which uses ammonia as fuel, an engine case 70 having an oil pan 71 which receives lubricating oil supplied to a sliding portion of the engine 2, a sump tank 130 which is provided outside the engine case 70 and into which the lubricating oil accumulated in the oil pan 71 is introduced, and a vent pipe 140 which airtightly connects a gas phase portion of the sump tank 130 with a gas phase portion of the engine case 70.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Patent Document 1 listed below discloses a reciprocating engine system that uses ammonia as fuel. This reciprocating engine system includes a reciprocating engine having a cylinder that forms a combustion chamber, a piston that reciprocates within the cylinder, an ammonia fuel supply device that supplies gaseous ammonia to the cylinder and premixes it with air, and a liquid auxiliary fuel supply device that supplies liquid auxiliary fuel into the cylinder to ignite the ammonia, and a control device that performs a mixed combustion operation using the ammonia and the liquid auxiliary fuel when the compression end temperature within the cylinder is equal to or higher than a predetermined temperature at which no combustion delay of the ammonia occurs.

[0003] Furthermore, Patent Document 2 listed below discloses a lubricating oil sump device that supplies lubricating oil to an engine. This lubricating oil sump device includes a lubricating oil pump that supplies lubricating oil to the engine, an oil pan that can hold a volume of lubricating oil equivalent to the volume of lubricating oil circulated by the lubricating oil pump, a lubricating oil sump tank that is provided outside the engine and holds lubricating oil to be replenished to the oil pan, an overflow pipe that returns lubricating oil that has exceeded a predetermined level set in the oil pan and overflowed out of the oil pan to the lubricating oil tank by its own weight, and a supply pump that replenishes the lubricating oil in the lubricating oil sump tank to the oil pan. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 90218 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-349008 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand to reduce emissions of carbon dioxide (CO2), a greenhouse gas, as a measure to combat global warming. Ammonia (NH3) has attracted attention as a new fuel that does not produce carbon dioxide when burned. When the lubricating oil sump device is applied to the reciprocating engine system, the following problems may arise. For example, because the oil level in the sump tank fluctuates depending on the operating conditions of the engine, a gas phase exists at the top of the sump tank, and a vent is provided to allow outside air to enter and exit. Here, if ammonia is used as engine fuel, there is a possibility that ammonia mixed in the lubricating oil will gasify in the sump tank and leak into the surrounding area through the vent. Ammonia gas is harmful to the human body, so if ammonia gas leaks into the work space around the engine, safety issues may arise.

[0006] The present invention has been made in view of the above circumstances, and has as its object to improve the safety of engine systems that use ammonia as fuel. [Means for solving the problem]

[0007] An engine system according to one aspect of the present invention includes an engine that uses ammonia as fuel, an engine case provided with an oil pan that receives lubricating oil supplied to sliding parts of the engine, a sump tank provided outside the engine case and into which the lubricating oil accumulated in the oil pan is introduced, and an air vent pipe that airtightly connects a gas phase portion of the sump tank with a gas phase portion of the engine case.

[0008] In the above engine system, the sump tank may be located below the engine case and include a first oil pipe that allows lubricating oil collected in the oil pan to flow down to the sump tank, and a second oil pipe that supplies the lubricating oil collected in the sump tank to sliding parts of the engine using a pump.

[0009] The engine system may further include an exhaust treatment device provided in the exhaust passage of the engine for treating unburned ammonia, and an suction device for creating negative pressure inside the engine case, and the unburned ammonia sucked from the engine case by the suction device may be treated by the exhaust treatment device. [Effects of the Invention]

[0010] According to the above aspect of the present invention, it is possible to improve the safety of an engine system that uses ammonia as fuel. Furthermore, the above aspect of the present invention can be a simple and useful means, particularly for small ships where it is difficult to direct the vent to a safe location in the atmosphere. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a configuration diagram of an engine system according to an embodiment. [Figure 2] FIG. 3 is an explanatory diagram illustrating the operation of a diesel operation mode of the engine system according to one embodiment. [Figure 3] FIG. 2 is an explanatory diagram illustrating an operation in an ammonia operation mode of the engine system according to one embodiment. [Figure 4] FIG. 2 is a cross-sectional view of the engine body according to the embodiment. [Figure 5] FIG. 1 is a diagram showing an exhaust gas discharge system of an engine system according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] FIG. 1 is a configuration diagram of an engine system 1 according to one embodiment. As shown in Fig. 1, the engine system 1 includes an engine 2 and a control device 3. The engine system 1 is a marine engine that directly or indirectly drives a propeller. Note that the engine system 1 may also be a power generation engine that drives a generator.

[0014] The engine system 1 generally includes a cylinder 11 that forms a combustion chamber 10, a piston 12 that reciprocates within the cylinder 11, a crank 13 connected to the piston 12, a rotation detection sensor 14 that detects the rotation of the crank 13, and a torque detection sensor 15 that detects the torque of the crank 13. The shaft of the crank 13 is connected to, for example, a propeller of a ship.

[0015] An intake passage 20 and an exhaust passage 30 are connected to a cylinder head 16 of the cylinder 11. An intake valve 21 that opens and closes the intake passage 20 and an exhaust valve 31 that opens and closes the exhaust passage 30 are also installed in the cylinder head 16. A liquid fuel injection valve 53 that injects liquid auxiliary fuel into the combustion chamber 10 and an ignition device 55 are also installed in the cylinder head 16. The ignition device 55 is, for example, a micro-pilot oil injection valve, and is used in an ammonia operation mode (first operation mode) described later.

[0016] The intake passage 20 includes a compressor 22 that compresses air for combustion, an air heater 24 installed downstream of the compressor 22, an air cooler 23 installed downstream of the air heater 24, and a fuel gas injector 43 installed downstream of the air cooler 23. The fuel gas injector 43 injects gaseous ammonia, which serves as fuel, into the intake passage 20. The gaseous ammonia is premixed with compressed air in the intake passage 20 to form an air-fuel mixture, which is supplied into the cylinder 11.

[0017] The air heating device 24 has a cooling and heating system 25 that uses, as a heat source, a refrigerant that has exchanged heat with the engine 2. The air cooler 23 has a function of cooling air with cold water. Note that the air cooler 23 may also be an air cooler / heating device that has a function of heating air with hot water, a heater, or the like.

[0018] The exhaust passage 30 includes a turbine 33 that is rotated by the exhaust gas discharged from the combustion chamber 10, and an exhaust treatment device 60 that is installed downstream of the turbine 33 and treats substances contained in the exhaust gas. The rotating shaft of the turbine 33 is connected to the compressor 22, and the exhaust gas serves as a rotation source to rotate the compressor 22. In other words, the turbine 33 and the compressor 22 constitute a turbocharger 4.

[0019] The exhaust treatment device 60 uses a catalyst to treat specific substances such as nitrogen oxides (NOx), nitrous oxide, and unburned ammonia that are generated by the combustion of ammonia and liquid auxiliary fuel. The exhaust treatment device 60 is equipped with a detection sensor 60a that detects the specific substances.

[0020] Engine 2 is equipped with an ammonia fuel supply device 40 that supplies ammonia into cylinder 11, and a liquid auxiliary fuel supply device 50 that supplies liquid auxiliary fuel that ignites the ammonia into cylinder 11. Ammonia fuel supply device 40 generally includes an ammonia tank 41, a vaporizer 42, and a fuel gas injector 43.

[0021] Ammonia tank 41 stores liquid ammonia. Vaporizer 42 vaporizes the liquid ammonia discharged from ammonia tank 41 to generate gaseous ammonia. Vaporizer 42 may include a pressure pump that pressurizes the gaseous ammonia. Vaporizer 42 is connected to fuel gas injection valve 43 via an ammonia supply path 44. Ammonia supply path 44 includes a regulator 44a and a pressure sensor 44b installed downstream of regulator 44a.

[0022] The ammonia supply path 44 also includes a second ammonia supply path 45 that branches off upstream of the regulator 44a. The second ammonia supply path 45 is connected to the above-mentioned exhaust treatment device 60. The second ammonia supply path 45 includes a regulator 45a and a pressure sensor 45b that is installed downstream of the regulator 45a.

[0023] The exhaust gas contains unburned ammonia and nitrogen oxides. In the exhaust treatment device 60, the unburned ammonia acts as a reducing agent that removes oxygen from the nitrogen oxides. When the rate at which unburned ammonia is generated is insufficient compared to the rate at which nitrogen oxides are generated, the shortage of gaseous ammonia is injected from the second ammonia supply passage 45 into the exhaust treatment device 60. As a result, the nitrogen oxides are reduced by the unburned ammonia, and the unburned ammonia is oxidized by the oxygen in the exhaust gas and rendered harmless.

[0024] The liquid auxiliary fuel supply device 50 includes a liquid auxiliary fuel tank 51, a first liquid fuel supply pump 52, a liquid fuel injection valve 53, a second liquid fuel supply pump 54, and an ignition device 55. The liquid auxiliary fuel tank 51 stores liquid auxiliary fuel such as heavy oil, light oil, or gasoline. The first liquid fuel supply pump 52 supplies the liquid auxiliary fuel stored in the liquid auxiliary fuel tank 51 to the liquid fuel injection valve 53.

[0025] Liquid fuel injection valve 53 is, for example, a mechanical fuel injection device used in a diesel operation mode (second operation mode) described later. Second liquid fuel supply pump 54 supplies liquid auxiliary fuel stored in liquid auxiliary fuel tank 51 to ignition device 55. Ignition device 55 is, for example, a common rail fuel injection device used in an ammonia operation mode.

[0026] The control device 3 is realized by, for example, a processor such as a CPU (Central Processing Unit) executing a program stored in a storage unit. Alternatively, the control device 3 may be realized by hardware such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array).

[0027] The storage unit is realized by, for example, a hard disk drive (HDD), flash memory, electrically erasable programmable read-only memory (EEPROM), read-only memory (ROM), or random access memory (RAM), etc. The storage unit stores firmware, programs executed by the processor, etc.

[0028] In the control device 3, for example, the output (work load [kW]) for the current load is calculated based on the rotation speed detected by the rotation detection sensor 14 and the torque detected by the torque detection sensor 15, and the load factor is calculated based on this current output and the rated output stored in advance in a storage unit. The load factor is calculated, for example, by dividing the current output by the rated output.

[0029] The control device 3 performs feedback control of the boost pressure based on the derived boost pressure target value based on the load factor of the engine 2 and the boost pressure measured by a pressure gauge (not shown). The boost pressure target value derivation information is information that indicates the relationship between a predetermined load factor and the boost pressure target value. This information is stored in advance in a storage unit as, for example, a map or a function. As a result, the control device 3 supplies fuel based on the load factor of the internal combustion engine during operation.

[0030] The engine system 1 configured as described above can be switched between an ammonia operation mode (first operation mode) in which the fuel used includes ammonia, and a diesel operation mode (second operation mode) in which a liquid auxiliary fuel (such as heavy oil) is used. Note that, since ammonia is more difficult to burn than liquid auxiliary fuel (such as heavy oil), in the ammonia operation mode, a mixed combustion operation using ammonia and the liquid auxiliary fuel is performed. For this reason, the ammonia operation mode is also called a mixed combustion operation mode.

[0031] In the ammonia operation mode (co-firing operation mode), the maximum co-firing rate of ammonia near maximum output is 80% or more in terms of heat value ratio.

[0032] FIG. 2 is an explanatory diagram illustrating the operation of the engine system 1 in the diesel operation mode according to one embodiment. 2, in the diesel operation mode, liquid auxiliary fuel is injected from the liquid fuel injector 53 into the combustion chamber 10, and is ignited and burned in the compressed air compressed by the piston 12. At this time, the fuel gas injector 43 is stopped.

[0033] FIG. 3 is an explanatory diagram illustrating the operation of the engine system 1 in the ammonia operation mode according to one embodiment. As shown in Fig. 3, in the ammonia operation mode, gaseous ammonia is injected from the fuel gas injector 43 into the intake passage 20 and premixed with air before the combustion chamber 10. Next, liquid auxiliary fuel for ignition is injected from the ignition device 55 into the combustion chamber 10, and the air-fuel mixture compressed by the piston 12 is ignited and burned. At this time, the liquid fuel injector 53 is stopped.

[0034] FIG. 4 is a cross-sectional view of the engine 2 according to one embodiment. As shown in Figure 4, the engine 2 includes a cylinder 11 that defines a combustion chamber 10, a piston 12 that reciprocates within the cylinder 11, a crank 13 connected to the piston 12, and an engine case 70 that houses the crank 13 and other components. The crank 13 is connected to the piston 12 via a connecting rod 13a. The dotted arrows in Figure 4 indicate the flow of blow-by gas. Blow-by gas is gas that leaks out from the gap between the piston 12 and the cylinder 11.

[0035] The bottom of the engine case 70 is formed by an oil pan 71. The oil pan 71 stores lubricating oil to be supplied to sliding parts such as the crank 13. A crank chamber 72 and a cam chamber 73 are provided inside the engine case 70. The crank chamber 72 houses the crank 13. The cam chamber 73 houses a cam mechanism 80 that drives the exhaust valve 31. The cam chamber 73 is located above the crank chamber 72 and is in communication with the crank chamber 72.

[0036] The cam mechanism 80 includes a cam 81 that rotates in conjunction with the crank 13, a tappet roller mechanism 82 that contacts the circumferential surface of the cam 81, and a push rod 83 that is pushed up by the tappet roller mechanism 82. The push rod 83 is disposed in a through hole 74 formed in the cylinder head 16, and its tip extends into the head cover 17 attached to the upper surface of the cylinder head 16.

[0037] A rocker arm 84 and a valve spring 85 are housed within the head cover 17. The valve spring 85 urges the exhaust valve 31 upward, closing the exhaust communication passage 30a that communicates with the exhaust path 30. When the rocker arm 84 is pushed up by the tip of the push rod 83, it pushes the exhaust valve 31 down against the urging of the valve spring 85, opening the exhaust communication passage 30a. Although not shown, the cam mechanism 80 also drives the intake valve 21 (see FIG. 1) using a similar mechanism.

[0038] The interior of the head cover 17 is in communication with the crank chamber 72 via the through-hole 74 and the cam chamber 73. Blow-by gas accompanied by oil mist flows into the head cover 17 from the crank chamber 72 via the cam chamber 73 and the through-hole 74. Therefore, the interior of the head cover 17 forms a gas retention section 16A where the blow-by gas tends to retain. A suction port 90 is formed in the head cover 17. A suction pipe 91 is connected to the suction port 90.

[0039] A sump tank 130 is provided outside the engine case 70. The sump tank 130 is disposed below the engine case 70, and lubricating oil collected in the oil pan 71 is introduced into the sump tank 130. The engine system 1 is equipped with a first oil pipe 131 that allows the lubricating oil collected in the oil pan 71 to flow down to the sump tank 130, and a second oil pipe 132 that supplies the lubricating oil collected in the sump tank 130 to the sliding parts of the engine 2 by a pump 133. The lubricating oil circulates between the engine case 70 and the sump tank 130 during operation.

[0040] One end of the first oil pipe 131 is connected to the bottom of the oil pan 71. The other end of the first oil pipe 131 extends to near the bottom of the sump tank 130. Furthermore, one end of the second oil pipe 132 is connected to the bottom of the sump tank 130. The other end of the second oil pipe 132 is connected to the lubricating oil supply port 2a of the engine case 70. The lubricating oil supplied to the lubricating oil supply port 2a passes through flow paths (not shown) and is supplied to each sliding part such as the crank 13.

[0041] The second oil pipe 132 is provided with a pump 133 that draws up lubricating oil from the sump tank 130, and a heat exchanger 134 that is installed downstream of the pump 133. The lubricating oil drawn up from the sump tank 130 by the pump 133 passes through the heat exchanger 134 and is cooled, etc., before being supplied to the lubricating oil supply port 2a.

[0042] The sump tank 130 and the engine case 70 are airtightly connected by a vent pipe 140. One end 141 of the vent pipe 140 is connected to the gas phase of the sump tank 130. In this embodiment, one end 141 of the vent pipe 140 is connected to the ceiling of the sump tank 130. The other end 142 of the vent pipe 140 is connected to the gas phase of the engine case 70. In this embodiment, the other end 142 of the vent pipe 140 is connected to a portion above the oil pan 71, where lubricating oil is less likely to penetrate, and which avoids the area directly below the sliding parts.

[0043] The sump tank 130 has a sealed structure with no vent pipe. The level of the lubricating oil in the sump tank 130 rises and falls depending on the operating conditions of the engine 2, but because the sump tank 130 and the engine case 70 are airtightly connected by the vent pipe 140, the lubricating oil and gas move in a complementary manner. Therefore, the rise and fall of the oil level in the sump tank 130 is not impeded.

[0044] FIG. 5 is a diagram showing an exhaust gas discharge system of the engine system 1 according to one embodiment. As shown in Figure 5, the engine 2 is provided with a plurality of cylinders (six cylinders 11). However, the number of cylinders in the engine 2 is not limited to six. An engine case 70 is provided in common to all the cylinders, and blow-by gas from each cylinder and unburned ammonia vaporized in a sump tank 130 flow into a crank chamber 72. The engine case 70 is provided with a main suction port 75 that communicates with the crank chamber 72, at a location separate from the suction port 90 of each head cover 17 (see Figure 4).

[0045] The main suction port 75 and the suction ports 90 of each head cover 17 are connected to a suction path 100. The suction path 100 is provided with a suction device 110 and an oil mist separator 120. The suction device 110 creates negative pressure inside the engine case 70 through the suction path 100. The oil mist separator 120 is disposed on the suction side (upstream side) of the suction device 110, and separates oil mist contained in gas sucked from inside the engine case 70.

[0046] The suction device 110 includes a blower 111, a motor 112, a pressure gauge 113, and an inverter 114. The blower 111 is driven by the motor 112 and creates negative pressure inside the engine case 70. The pressure gauge 113 measures the pressure inside the engine case 70. The inverter 114 drives the motor 112 based on the measurement result of the pressure gauge 113. The inverter 114 drives the blower 111 so that the measurement result of the pressure gauge 113 becomes negative pressure (for example, -0.2 kPa).

[0047] According to the above configuration, by suctioning the inside of the engine case 70 under negative pressure, it is possible to suppress leakage of unburned ammonia to the outside of the engine 2. Furthermore, by suctioning gas from inside each head cover 17 (gas accumulation portion 16A) under negative pressure, it is possible to suppress the accumulation of gas containing unburned ammonia inside each head cover 17.

[0048] An exhaust passage 30 through which exhaust gas is discharged from the engine 2 is provided with an exhaust treatment device 60. A suction passage 100 that draws air into the engine case 70 branches into a first discharge passage 101 and a second discharge passage 102 upstream of an oil mist separator 120. The pressure within the exhaust passage 30 is, for example, 5 kPa. The pressure on the discharge side (downstream side) of the suction device 110 is preferably set to a pressure that prevents gas from flowing back from the exhaust passage 30. If backflow from the exhaust passage 30 occurs, a check valve may be provided on the discharge side (downstream side) of the suction device 110.

[0049] An oil mist separator 120 and a suction device 110 are provided in the first discharge path 101. The first discharge path 101 is connected to the exhaust passage 30 on the upstream side of the exhaust treatment device 60. The oil mist separator 120 includes a first separation section 121 and a second separation section 122, and is provided with a return flow path 124 that returns oil separated in each separation section to the inside of the engine case 70. Differential pressure gauges 123 are connected to the upstream and downstream sides of the oil mist separator 120. The differential pressure gauges 123 measure the differential pressure between the upstream and downstream sides of the oil mist separator 120 to detect abnormalities in the oil mist separator 120, such as clogging.

[0050] A switching device 150 is provided at the branch point between the first exhaust path 101 and the second exhaust path 102. The switching device 150 switches the connection destination of the suction path 100 between the first exhaust path 101 and the second exhaust path 102. In the ammonia operation mode, the suction path 100 is connected to the first exhaust path 101, and gas inside the engine case 70 is sucked in by the suction device 110, introduced into the exhaust treatment device 60 of the exhaust passage 30, treated, and then released to the atmosphere.

[0051] Furthermore, when the suction path 100 is connected to the second exhaust path 102, the gas inside the engine case 70 is released directly to the atmosphere without being introduced into the exhaust passage 30 (exhaust treatment device 60) and treated. In the diesel operation mode, ammonia is not used as fuel, so the suction path 100 that sucks gas inside the engine case 70 is connected to the second exhaust path 102, and the gas inside the engine case 70 is released to the atmosphere.

[0052] As described above, engine system 1 according to this embodiment includes engine 2 that uses ammonia as fuel, engine case 70 provided with oil pan 71 that receives lubricating oil supplied to sliding parts of engine 2, sump tank 130 provided outside engine case 70 and into which lubricating oil collected in oil pan 71 is introduced, and vent pipe 140 that airtightly connects the gas phase of sump tank 130 with the gas phase of engine case 70. This configuration prevents unburned ammonia that dissolves in the lubricating oil and is gasified in sump tank 130 from leaking to the surrounding area. Furthermore, gas can enter and exit sump tank 130 through vent pipe 140, so the oil level in sump tank 130 does not rise or fall. This can improve the safety of the engine system 1 that uses ammonia as fuel. Furthermore, this configuration can be a simple and useful means, particularly for small ships where it is difficult to direct the vent to a safe location in the atmosphere.

[0053] In this embodiment, sump tank 130 is disposed below engine case 70 and includes a first oil pipe 131 that allows lubricating oil collected in oil pan 71 to flow down to sump tank 130, and a second oil pipe 132 that supplies lubricating oil collected in sump tank 130 to sliding parts of engine 2 using pump 133. With this configuration, when engine 2 is operating, lubricating oil in sump tank 130 is sent into engine 2, causing the oil level in sump tank 130 to drop, but to compensate for this, gas in engine case 70 moves into sump tank 130. When engine 2 is stopped, lubricating oil in engine 2 flows down to sump tank 130, causing the oil level in sump tank 130 to rise, but to compensate for this, gas in sump tank 130 moves into engine case 70. In this way, the lubricating oil and gas move in a complementary manner, so that the oil level in the sump tank 130 does not rise or fall according to the operating conditions, even though the engine case 70 and the sump tank 130 have an airtight structure. The first oil pipe 131 and the second oil pipe 132 are both connected to the sump tank 130 and the engine case 70 in a liquid-tight and airtight manner.

[0054] Furthermore, this embodiment includes an exhaust treatment device 60 that is provided in the exhaust path 30 of the engine 2 and treats unburned ammonia, and a suction device 110 that creates negative pressure inside the engine case 70. The unburned ammonia sucked from the engine case 70 by the suction device 110 is treated by the exhaust treatment device 60. With this configuration, both the sump tank 130 and the engine case 70 are suctioned to negative pressure, preventing gas containing ammonia from leaking into the vicinity of the engine 2. The sump tank 130 itself has an airtight structure, and is placed under a negative pressure relative to the surroundings by suction, providing a double barrier against ammonia leakage. The sucked gas is combined with the exhaust gas from the engine 2 and treated by a catalyst that treats the exhaust gas from the engine 2, where it is rendered harmless.

[0055] While preferred embodiments of the present invention have been described and illustrated, it should be understood that these are illustrative of the present invention and should not be considered limiting. Additions, omissions, substitutions, and other modifications may be made without departing from the scope of the present invention. While the preferred embodiment has been described with reference to a four-stroke engine, the same principles apply to a two-stroke engine. Accordingly, the present invention should not be deemed limited by the foregoing description, but rather by the scope of the appended claims. [Explanation of symbols]

[0056] 1 Engine System 2 engines 2a Lubrication port 3. Control device 4. Turbocharger 10 Combustion chamber 11 cylinders 12 pistons 13 Crank 13a Connecting rod 14 Rotation detection sensor 15 Torque detection sensor 16 Cylinder head 16A Gas accumulation section 17 Headcover 20 Intake passage 21 Intake valve 22 Compressor 23 Air cooler 24 Air heating device 25 Cooling and heating system 30 Exhaust duct 30a Exhaust passage 31 Exhaust valve 33 Turbine 40 Ammonia fuel supply device 41 Ammonia Tank 42 Vaporizer 43 Fuel gas injection valve 44 Ammonia supply line 44a regulator 44b Pressure sensor 45 Ammonia second supply line 45a regulator 45b Pressure sensor 50 Liquid auxiliary fuel supply system 51 Liquid auxiliary fuel tank 52 No. 1 liquid fuel supply pump 53 Liquid fuel injection valve 54 No. 2 liquid fuel supply pump 55 Ignition device 60 Exhaust treatment device 60a detection sensor 70 Engine Case 71 Oil pan 72 Crankcase 73 Cam chamber 74 Through Hole 75 Main suction port 80 Cam mechanism 81 Cam 82 Tappet roller mechanism 83 Push rod 84 rocker arm 85 valve spring 90 Suction port 91 Suction tube 100 Suction path 101 First Emission Route 102 Secondary Emission Route 110 Suction device 111 Blower 112 Motor 113 Pressure Gauge 114 Inverter 120 Oil mist separator 121 1st separation section 122 2nd separation section 123 Differential pressure gauge 124 Return channel 130 Sump tank 131 First oil pipe 132 Second oil pipe 133 Pump 134 Heat exchanger 140 Ventilation pipe 141 one end 142 other end 150 Switching Device

Claims

1. an engine that uses ammonia as fuel; an engine case provided with an oil pan for receiving lubricating oil supplied to sliding parts of the engine; a sump tank provided outside the engine case and into which lubricating oil accumulated in the oil pan is introduced; a vent pipe airtightly connecting a gas space portion of the sump tank and a gas space portion of the engine case, Engine system.

2. The sump tank is disposed below the engine case, a first oil pipe through which the lubricating oil collected in the oil pan flows down to the sump tank; a second oil pipe that supplies the lubricating oil stored in the sump tank to the sliding parts of the engine by a pump. The engine system of claim 1 .

3. an exhaust treatment device provided in an exhaust passage of the engine and configured to treat unburned ammonia; a suction device that creates a negative pressure inside the engine case, The unburned ammonia sucked from the engine case by the suction device is treated by the exhaust treatment device.

3. The engine system according to claim 1 or 2.

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