Reciprocating engine

Abstract

A reciprocating engine using ammonia as fuel includes: a cylinder forming a combustion chamber; an exhaust passage that discharges exhaust gas from the combustion chamber; an exhaust gas treatment device which is provided in the exhaust gas path and treats unburned ammonia; a piston which reciprocates in the cylinder; a crankshaft connected to the piston; a crankcase which accommodates the crankshaft and into which blow-by gas flows from the combustion chamber; and a suction device for performing negative pressure suction in the crankcase, in which unburned ammonia contained in the blow-by gas sucked from the crankcase by the suction device is treated by the exhaust gas treatment device.

Description

Technical Field

[0001] The present invention relates to a reciprocating engine.

[0002] This application claims priority based on Japanese Patent Application No. 2023-013146 filed in Japan on January 31, 2023, and incorporates its content herein. Background Art

[0003] In Patent Document 1 below, a blow-by gas treatment system applicable to an engine system is disclosed. The engine system includes an engine, a turbocharger, and an oxidation catalyst. The turbocharger has a compressor disposed in the intake passage of the engine and a turbine disposed in the exhaust passage of the engine. The oxidation catalyst is disposed in the exhaust passage on the downstream side of the turbine. This blow-by gas treatment system includes a blow-by gas introduction switching mechanism that, when the conditions of being in a high load state where the load ratio of the engine is greater than a specified load and the oxidation catalyst is in an active state are satisfied, introduces the blow-by gas discharged from the engine into the oxidation catalyst, and when the conditions are not satisfied, introduces the blow-by gas discharged from the engine into the compressor.

[0004] Prior Art Documents Patent Documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-76779 Summary of the Invention

[0005] Technical Problem to be Solved by the Invention However, in recent years, as a countermeasure against global warming, it has been required to reduce the emissions of carbon dioxide (CO2), which is a greenhouse gas. Ammonia (NH3) has attracted attention as a new fuel that does not produce carbon dioxide during combustion.

[0006] However, since ammonia is toxic, when used as a fuel for a reciprocating engine, safety problems may sometimes occur if its blow-by gas remains in the crankcase or leaks outside the crankcase.

[0007] The present invention has been completed in view of the above circumstances, and its object is to improve the safety of a reciprocating engine using ammonia as a fuel.

[0008] Technical Solution for Solving the Technical Problem A reciprocating engine according to an embodiment of the present invention is a reciprocating engine that uses ammonia as fuel, and includes: a cylinder that forms a combustion chamber; an exhaust passage that discharges exhaust gas from the combustion chamber; an exhaust treatment device that is provided in the exhaust passage and treats unburned ammonia; a piston that reciprocates within the cylinder; a crankshaft that is connected to the piston; a crankcase that houses the crankshaft, and blow-by gas flows from the combustion chamber into the crankcase; and a suction device that negatively suctions the inside of the crankcase, wherein the exhaust treatment device treats unburned ammonia contained in the blow-by gas suctioned from the crankcase by the suction device.

[0009] In the above reciprocating engine, the exhaust treatment device may be a catalyst treatment device that uses a catalyst to treat unburned ammonia.

[0010] In the above reciprocating engine, the suction device may have a pressure gauge that measures the pressure inside the crankcase, and a blower that suctions the inside of the crankcase to a negative pressure, pressurizes the suctioned gas, and discharges it to the exhaust passage, wherein the blower is driven such that the measurement result of the pressure gauge becomes a specified value of negative pressure.

[0011] In the above reciprocating engine, the suction device may negatively suction the inside of the crankcase through a suction port provided in a gas retention portion that communicates with the inside of the crankcase.

[0012] In the above reciprocating engine, the gas retention portion may be formed on a cylinder head.

[0013] In the above reciprocating engine, a gas inlet may be provided in a gas retention portion that communicates with the inside of the crankcase, and the suction device negatively suctions the inside of the crankcase through a suction port provided at a position other than the gas retention portion where the gas inlet is provided.

[0014] In the above reciprocating engine, a gas supply device that supplies gas from the gas inlet to the gas retention portion may be included.

[0015] In the above reciprocating engine, a first discharge route that connects the inside of the crankcase to the exhaust passage through the suction device, a second discharge route that does not connect the inside of the crankcase to the exhaust passage and opens the inside of the crankcase to the atmosphere, and a switching device that switches the first discharge route and the second discharge route according to the operating condition of the reciprocating engine may be included.

[0016] In the above reciprocating engine, the reciprocating engine can be switched to a first operation mode in which ammonia is contained in the fuel in use and a second operation mode in which a fuel other than ammonia is used. The switching device can be switched to the first discharge route in the first operation mode and switched to the second discharge route in the second operation mode.

[0017] In the above reciprocating engine, the switching device can be switched from the first discharge route to the second discharge route after a certain period of time from the switching from the first operation mode to the second operation mode.

[0018] In the above reciprocating engine, the switching device can be immediately switched from the second discharge route to the first discharge route when switching from the second operation mode to the first operation mode.

[0019] In the above reciprocating engine, an oil mist separator can be provided on the suction side of the suction device.

[0020] Advantages of the Invention According to one embodiment of the present invention described above, the safety of a reciprocating engine using ammonia as a fuel can be improved. Description of the Drawings

[0021] Figure 1 It is a structural diagram of a reciprocating engine according to one embodiment.

[0022] Figure 2 It is an explanatory diagram showing the operation of the diesel operation mode of a reciprocating engine according to one embodiment.

[0023] Figure 3 It is an explanatory diagram showing the operation of the ammonia operation mode of a reciprocating engine according to one embodiment.

[0024] Figure 4 It is a cross-sectional structural diagram of an engine body according to one embodiment.

[0025] Figure 5 It is a schematic structural diagram of an engine body according to one embodiment.

[0026] Figure 6 It is a schematic structural diagram of an engine body according to other embodiments.

[0027] Figure 7 It is a diagram showing an exhaust gas and blow-by gas emission system of a reciprocating engine according to one embodiment.

[0028] Figure 8 It is a schematic diagram showing the blow-by gas emission destination of a reciprocating engine according to one embodiment.

[0029] Figure 9It is a diagram showing the blow-by (oil mist) emission destinations in different situations of a reciprocating engine according to an embodiment. Detailed Embodiment

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0031] Figure 1 It is a structural diagram of a reciprocating engine 1 according to an embodiment.

[0032] As Figure 1 shown, the reciprocating engine 1 has an engine body 2 and a control device 3. The reciprocating engine 1 is a marine engine that directly or indirectly drives a propeller. In addition, the reciprocating engine 1 can be a power generation engine that drives a generator.

[0033] The reciprocating engine 1 generally includes: a cylinder 11 that forms a combustion chamber 10, a piston 12 that reciprocates in the cylinder 11, a crankshaft 13 connected to the piston 12, a rotation detection sensor 14 that detects the rotation of the crankshaft 13, and a torque detection sensor 15 that detects the torque of the crankshaft 13. The shaft of the crankshaft 13 is connected to, for example, the propeller of a ship.

[0034] An intake passage 20 and an exhaust passage 30 are connected to the cylinder head 16 of the cylinder 11. In addition, 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 provided on the cylinder head 16. Further, a liquid fuel injection valve 53 that injects liquid auxiliary fuel into the combustion chamber 10 and an ignition device 55 are provided on the cylinder head 16. The ignition device 55 is, for example, a micro pilot oil injection valve and is used in the ammonia operation mode (the first operation mode) described later.

[0035] The intake passage 20 has a compressor 22 that compresses combustion air, an air cooler 23 provided on the downstream side of the compressor 22, and a fuel gas injection valve 43 provided on the downstream side of the air cooler 23. The fuel gas injection valve 43 injects gaseous ammonia as fuel into the interior of the intake passage 20. The gaseous ammonia is pre-mixed with the compressed air in the intake passage 20 to form a mixed gas, which is supplied into the cylinder 11.

[0036] In addition, the air cooler 23 can be an air cooler and heating device that not only has the function of cooling air using cold water but also has the function of heating air using warm water or a heater, etc. Further, according to need, an air heating device 24 can be provided on the upstream side of the compressor 22 in the intake passage 20. The air heating device 24 can, for example, have a cooling and heating system 25 that uses a refrigerant after heat exchange with the engine body 2 as a heat source.

[0037] The exhaust passage 30 has a turbine 33 that rotates by the exhaust gas discharged from the combustion chamber 10, and a catalyst treatment device 60 provided on the downstream side of the turbine 33 that treats substances contained in the exhaust gas. The rotating shaft of the turbine 33 is connected to the compressor 22 to rotate the compressor 22 using the exhaust gas as a rotation source. That is, the turbine 33 and the compressor 22 constitute a supercharger 4.

[0038] The catalyst treatment device 60 uses a catalyst to treat specific substances such as nitrogen oxides (NOx), nitrous oxide, and unburned ammonia generated by the combustion of ammonia and liquid auxiliary fuel. A detection sensor 60a for detecting this specific substance is installed in the catalyst treatment device 60.

[0039] The engine body 2 has an ammonia fuel supply device 40 that supplies ammonia into the cylinder 11 and a liquid auxiliary fuel supply device 50 that supplies liquid auxiliary fuel for igniting ammonia into the cylinder 11. The ammonia fuel supply device 40 generally has an ammonia tank 41, a vaporization device 42, and a fuel gas injection valve 43.

[0040] The ammonia tank 41 stores liquid ammonia. The vaporization device 42 vaporizes the liquid ammonia discharged from the ammonia tank 41 to generate gaseous ammonia. The vaporization device 42 may include a pressure pump for pressurizing the gaseous ammonia. The vaporization device 42 is connected to the fuel gas injection valve 43 through an ammonia supply passage 44. The ammonia supply passage 44 has a regulator 44a and a pressure sensor 44b provided on the downstream side of the regulator 44a.

[0041] In addition, the ammonia supply passage 44 has an ammonia second supply passage 45 that branches on the upstream side of the regulator 44a. The ammonia second supply passage 45 is connected to the above-mentioned catalyst treatment device 60. The ammonia second supply passage 45 has a regulator 45a and a pressure sensor 45b provided on the downstream side of the regulator 45a.

[0042] The liquid auxiliary fuel supply device 50 has 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, and 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.

[0043] The liquid fuel injection valve 53 is, for example, a mechanical fuel injection device used in the diesel operation mode (second operation mode) described later. The second liquid fuel supply pump 54 supplies the liquid auxiliary fuel stored in the liquid auxiliary fuel tank 51 to the ignition device 55. The ignition device 55 is, for example, a common rail fuel injection device used in the ammonia operation mode.

[0044] The control device 3 is implemented, for example, by a processor such as a CPU (Central Processing Unit) executing a program stored in the storage unit. Alternatively, the control device 3 can also be implemented by hardware such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array).

[0045] The storage unit is implemented, for example, by an HDD (Hard Disc Drive), a flash memory, an EEPROM (Electrically Erasable Programmable Read Only Memory), a ROM (Read Only Memory), or a RAM (Random Access Memory), etc. Firmware, programs executed by the processor, etc. are stored in the storage unit.

[0046] In the control device 3, for example, based on the rotational speed detected by the rotation detection sensor 14 and the torque detected by the torque detection sensor 15, the output to the load at the current time (working load [kW]) is derived, and based on this output at the current time and the rated output pre-stored in the storage unit, the load factor is derived. The load factor is derived, for example, by dividing the output at the current time by the rated output.

[0047] The control device 3 performs feedback control on the supply air pressure based on the supply air pressure target value based on the load factor of the engine body 2 derived and the supply air pressure measured by a pressure gauge (not shown). The supply air pressure target value derivation information refers to information indicating the relationship between a pre-determined load factor and the supply air pressure target value. This information is pre-stored in the storage unit, for example, as a map or a function. Thereby, the control device 3 supplies fuel according to the load factor of the internal combustion engine during operation.

[0048] The reciprocating engine 1 with the above structure can be switched between an ammonia operation mode (first operation mode) in which ammonia is contained in the fuel being used and a diesel operation mode (second operation mode) using a liquid auxiliary fuel (such as heavy oil). In addition, since ammonia is more difficult to burn than the liquid auxiliary fuel (such as heavy oil), in the ammonia operation mode, a co-combustion operation based on ammonia and the liquid auxiliary fuel is performed. Therefore, the ammonia operation mode is also called the co-combustion operation mode.

[0049] In addition, in the ammonia operation mode (co-combustion operation mode), the maximum co-combustion rate of ammonia near the maximum output is 80% or more in terms of the heat ratio.

[0050] Figure 2 This is an explanatory diagram showing the operation of the reciprocating engine 1 in the diesel operation mode of one embodiment.

[0051] As Figure 2 shown, in the diesel operation mode, liquid auxiliary fuel is injected from the liquid fuel injection valve 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 injection valve 43 stops.

[0052] Figure 3 This is an explanatory diagram showing the operation of the reciprocating engine 1 in the ammonia operation mode of one embodiment.

[0053] As Figure 3 shown, in the ammonia operation mode, gaseous ammonia is injected from the fuel gas injection valve 43 into the intake passage 20, and is premixed with air in front of the combustion chamber 10. Then, liquid auxiliary fuel for ignition is injected from the ignition device 55 into the combustion chamber 10, and the mixed gas compressed by the piston 12 is ignited and burned. At this time, the liquid fuel injection valve 53 stops.

[0054] Figure 4 This is a sectional structure diagram of the engine body 2 of one embodiment.

[0055] As Figure 4 shown, the engine body 2 has a cylinder 11 forming the combustion chamber 10, a piston 12 reciprocating in the cylinder 11, a crankshaft 13 connected to the piston 12, and a crankcase 70 housing the crankshaft 13 and into which blow-by gas flows from the combustion chamber 10. The crankshaft 13 is connected to the piston 12 by a connecting rod 13a. In addition, Figure 4 The dotted arrows shown indicate the flow of blow-by gas. Blow-by gas refers to the gas leaking from the gap between the piston 12 and the cylinder 11.

[0056] The bottom of the crankcase 70 is formed by an oil pan 71. Lubricating oil supplied to sliding parts such as the crankshaft 13 is stored in the oil pan 71. A crankshaft chamber 72 and a cam chamber 73 are provided in the crankcase 70. The crankshaft 13 is housed in the crankshaft chamber 72. A cam mechanism 80 for driving the exhaust valve 31 is housed in the cam chamber 73. The cam chamber 73 is located above the crankshaft chamber 72 and communicates with the crankshaft chamber 72.

[0057] The cam mechanism 80 has a cam 81 that rotates in conjunction with the crankshaft 13, a tappet roller mechanism 82 that abuts against 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 front end extends into a cover 17 mounted on the upper surface of the cylinder head 16.

[0058] The rocker arm 84 and the valve spring 85 are accommodated in the cover 17. The valve spring 85 biases the exhaust valve 31 upward to close the exhaust communication passage 30a communicating with the exhaust passage 30. When the rocker arm 84 is pushed up by the front end of the push rod 83, the rocker arm 84 pushes the exhaust valve 31 downward against the biasing force of the valve spring 85 to open the exhaust communication passage 30a. In addition, although not shown, the cam mechanism 80 also drives the intake valve 21 through the same mechanism (see Figure 1 ).

[0059] The inside of the cover 17 communicates with the crankshaft chamber 72 through the through hole 74 and the cam chamber 73. The blow-by gas accompanied by the oil mist flows into the cover 17 from the crankshaft chamber 72 via the cam chamber 73 and the through hole 74. Therefore, the inside of the cover 17 becomes the gas retention portion 16A where the blow-by gas easily stays. An intake port 90 is formed in the cover 17. An intake pipe 91 is connected to the intake port 90.

[0060] Figure 5 It is a schematic structural diagram of the engine body 2 of an embodiment.

[0061] As Figure 5 shown, a plurality of ( Figure 4 six in the example) covers 17 are provided on the engine body 2. That is, a plurality of cylinders (six cylinders 11) are provided on the engine body 2. In addition, the number of cylinders of the engine body 2 is not limited to six. The crankcase 70 is commonly provided for each cylinder, and the blow-by gas from each cylinder flows into the crankshaft chamber 72. In the crankcase 70, a main intake port 75 communicating with the crankshaft chamber 72 is provided at a position different from the intake port 90 of each cover 17.

[0062] The main intake port 75 and the intake port 90 of each cover 17 are connected to the intake path 100. An intake device 110 and an oil mist separator 120 are provided in the intake path 100. The intake device 110 performs negative pressure intake on the inside of the crankcase 70 through the intake path 100. The oil mist separator 120 is disposed on the intake side (upstream side) of the intake device 110 to separate the oil mist contained in the intake blow-by gas.

[0063] The intake device 110 includes a blower 111, a motor 112, and a pressure gauge 113. The blower 111 is driven by the motor 112 to perform negative pressure intake on the inside of the crankcase 70. The pressure gauge 113 measures the pressure inside the crankcase 70. The intake device 110 drives the blower 111 so that the measurement result of the pressure gauge 113 is a negative pressure (for example, -0.2 kPa).

[0064] According to the above structure, by performing negative pressure suction inside the crankcase 70, it is possible to suppress the leakage of blow-by gas outside the engine body 2. In addition, by performing negative pressure suction of the blow-by gas from inside each cover 17 (gas retention portion 16A), it is possible to suppress the blow-by gas from staying inside each cover 17. Thus, even when the operator opens the cover 17 during maintenance, safety can be ensured.

[0065] In addition, the following structure can be adopted.

[0066] Figure 6 It is a schematic structural diagram of the engine body 2 of other embodiments.

[0067] In Figure 6 In the other embodiment shown, while performing negative pressure suction on the inside of the crankcase 70 from the main suction port 75, a gas introduction port 92 is provided in each cover 17. Gas is supplied from the gas supply device 130 to the gas introduction port 92.

[0068] A gas introduction pipe 93 is connected to each gas introduction port 92. The gas supply device 130 supplies gas from the gas supply path 131 to each gas introduction pipe 93. As this gas, a gas that does not react with the unburned ammonia contained in the blow-by gas is preferred, and it can be air or an inert gas such as nitrogen. As the gas supply device 130, a fan, a blower, a compressor, etc. can be exemplified, and it can also be used as other gas supply devices (such as the compressor 22) inside the ship.

[0069] According to the above structure, by performing negative pressure suction on the inside of the crankcase 70 from the main suction port 75 and supplying gas to the inside of each cover 17 (gas retention portion 16A) at the same time, the blow-by gas is expelled from inside the cover 17, and it is possible to suppress the blow-by gas from staying inside each cover 17. Thus, even when the operator opens the cover 17 during maintenance, safety can be ensured.

[0070] In addition, if the inside of the crankcase 70 is always maintained at a negative pressure by the suction device 110, it is only necessary to form a gas introduction port 92 for taking in external gas in the cover 17. That is, the gas supply device 130 may not be provided. In addition, in order to reliably prevent the blow-by gas from leaking from the gas introduction port 92, a check valve can be provided in the gas introduction pipe 93 or the gas supply path 131 connected to the gas introduction port 92, and its end is open to the atmosphere.

[0071] Figure 7 It is a diagram showing the exhaust gas and blow-by gas discharge system of the reciprocating engine 1 of one embodiment.

[0072] As Figure 7As shown, a catalyst treatment device 60 is provided in an exhaust passage 30 that discharges exhaust gas from an engine body 2. In a suction path 100 that sucks the inside of a crankcase 70, a first discharge path 101 and a second discharge path 102 branch off on the upstream side of an oil mist separator 120.

[0073] 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 upstream side of the catalyst treatment device 60 in the exhaust passage 30. The oil mist separator 120 has a first separation portion 121 and a second separation portion 122, and has a return flow path 124 that returns the oil separated by each separation portion to the inside of the crankcase 70. A differential pressure gauge 123 is connected to the upstream side and the downstream side of the oil mist separator 120. The differential pressure gauge 123 detects an abnormality such as clogging of the oil mist separator 120 by measuring the differential pressure between the upstream side and the downstream side of the oil mist separator 120.

[0074] In addition to a blower 111, a motor 112, and a pressure gauge 113, the suction device 110 further includes an inverter 114. The inverter 114 drives the motor 112 based on the measurement result of the pressure gauge 113. In addition, the pressure in 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 at which gas does not flow back from the exhaust passage 30. In addition, in the case of a backflow from the exhaust passage 30, a check valve can be provided on the discharge side (downstream side) of the suction device 110.

[0075] A switching device 140 is provided at the branch point between the first discharge path 101 and the second discharge path 102. The switching device 140 switches the connection destination of the suction path 100 to the first discharge path 101 or the second discharge path 102. When the suction path 100 is connected to the first discharge path 101, blow-by gas in the crankcase 70 is sucked by the suction device 110, introduced into the catalyst treatment device 60 in the exhaust passage 30 for treatment, and then released to the atmosphere. In addition, when the suction path 100 is connected to the second discharge path 102, the blow-by gas in the crankcase 70 is not introduced into the exhaust passage 30 (catalyst treatment device 60) for treatment, but is directly released to the atmosphere.

[0076] Figure 8 It is a schematic diagram showing the discharge destination of blow-by gas of a reciprocating engine 1 according to an embodiment.

[0077] As Figure 8As shown, the catalyst treatment device 60 has a first treatment tank 61 for treating unburned ammonia (NH3) and nitrous oxide (N2O) and a second treatment tank 62 for treating nitrogen oxides (NOx). A flow path switching valve 34 is provided in the exhaust path 30 on the upstream side of the catalyst treatment device 60, which can switch between the first exhaust path 30A connected to the first treatment tank 61 and the second exhaust path 30B connected to the second treatment tank 62. In addition, Figure 8 Indicated by reference numeral 103 is a check valve provided on the downstream side of the suction device 110 .

[0078] In the case of the diesel operation mode, the exhaust path 30 is usually connected to the second exhaust path 30B, and the exhaust gas (including nitrogen oxides) is introduced into the second treatment tank 62 for treatment. The nitrogen oxides contained in the exhaust gas are reduced in the second treatment tank 62. In addition, in the case of the diesel operation mode, the suction path 100 for sucking the inside of the crankcase 70 is usually connected to the second exhaust path 102, and the blow-by gas is released to the atmosphere.

[0079] On the other hand, in the case of the ammonia operation mode, the exhaust path 30 is usually connected to the first exhaust path 30A, and the exhaust gas (including unburned ammonia and nitrous oxide) is introduced into the first treatment tank 61 for treatment. In the first treatment tank 61, the unburned ammonia acts as a reducing agent that deprives the nitrous oxide of oxygen. When the generation ratio of unburned ammonia is insufficient relative to the generation ratio of nitrous oxide, the insufficient amount of gaseous ammonia is supplied from the second ammonia supply path 45 (see Figure 1 ) is sprayed into the first processing tank 61.

[0080] In the first treatment tank 61, nitrogen oxides are reduced by unburned ammonia, and unburned ammonia is oxidized by oxygen in the exhaust gas to be harmless. In the case of the ammonia operation mode, the suction path 100 for sucking the inside of the crankcase 70 is usually connected to the first exhaust path 101, and the blow-by gas (including unburned ammonia) is introduced into the exhaust path 30 and treated in the first treatment tank 61.

[0081] Thus, the reciprocating engine 1 is provided with a first exhaust route F1 that connects the inside of the crankcase 70 to the exhaust passage 30 via the suction device 110, and a second exhaust route F2 that does not connect the inside of the crankcase 70 to the exhaust passage 30 but opens to the atmosphere. The switching device 140 switches between the first exhaust route F1 and the second exhaust route F2 according to the operating condition of the reciprocating engine 1.

[0082] Typically, the switching device 140 switches to the first discharge route F1 in the ammonia operation mode and switches to the second discharge route F2 in the diesel operation mode. In addition, the switching device 140 switches between the first discharge route F1 and the second discharge route F2 according to various conditions of the reciprocating engine 1 .

[0083] Figure 9 FIG. is a diagram showing the blow-by (oil mist) emission destinations in different cases of the reciprocating engine 1 according to one embodiment.

[0084] As Figure 9 shown, the switching device 140 switches the blow-by (oil mist) emission destination to the first discharge route F1 or the second discharge route F2 in the first to ninth conditions. In addition, the following first to ninth are an example.

[0085] <First> During diesel operation mode (normal time), the switching device 140 switches to the second discharge route F2. In the diesel operation mode, since the blow-by does not contain unburned ammonia (NH3: none), the blow-by is made to flow into the second discharge route F2 and released to the atmosphere.

[0086] <Second> During ammonia operation mode (normal time), the switching device 140 switches to the first discharge route F1. In the ammonia operation mode, since the blow-by contains unburned ammonia (NH3: yes), the blow-by is made to flow into the first discharge route F1, and after being made harmless by the catalyst treatment device 60, it is released to the atmosphere.

[0087] <Third> Just after the diesel operation mode stops (normal time), the switching device 140 maintains the switching to the second discharge route F2. Since the blow-by just after the diesel operation mode stops does not contain unburned ammonia (NH3: none), the blow-by is made to flow into the second discharge route F2 and released to the atmosphere.

[0088] <Fourth> Just after the ammonia operation mode stops urgently (urgent time), the switching device 140 maintains the switching to the first discharge route F1 for several minutes. In addition, just after the ammonia operation mode stops urgently, the suction device 110 can be driven for several minutes. Thereby, the blow-by (NH3: yes) remaining in the crankcase 70 can be made to flow into the first discharge route F1 and made harmless by the catalyst treatment device 60.

[0089] <Fifth> When switching from the diesel operation mode to the ammonia operation mode (normal time), the switching device 140 immediately switches from the second discharge route F2 to the first discharge route F1. In the ammonia operation mode, since the blow-by contains unburned ammonia (NH3: yes), the blow-by is immediately made to flow into the first discharge route F1 and made harmless by the catalyst treatment device 60.

[0090] <Sixth> When switching from the ammonia operation mode to the diesel operation mode (usually), the switching device 140 switches from the first discharge route F1 to the second discharge route F2 after a certain time after the switching. Even when switching from the ammonia operation mode to the diesel operation mode, due to blow-by remaining in the crankcase 70 (NH3: present), it can flow into the first discharge route F1 within a few minutes after the switching and be rendered harmless through the catalyst treatment device 60.

[0091] 〈Article 7〉 In the ammonia operation mode, when the measured differential pressure measured by the differential pressure gauge 123 of the oil mist separator 120 (refer to Figure 7 ) rises (in case of emergency), the switching device 140 maintains the switching to the first discharge route F1. Thereby, the blow-by remaining in the crankcase 70 (NH3: present) can flow into the first discharge route F1 and be rendered harmless through the catalyst treatment device 60. In addition, an alarm can be sent, and after the blow-by is rendered harmless through the catalyst treatment device 60 for a few minutes, the components of the oil mist separator 120 are replaced.

[0092] 〈Article 8〉 In the ammonia operation mode, when it is detected that the suction device 110 (blower 111) fails and switches to the diesel operation mode (in case of emergency), the switching device 140 immediately switches from the first discharge route F1 to the second discharge route F2. This is because the first discharge route F1 cannot be used when the suction device 110 fails.

[0093] 〈Article 9〉 In the ammonia operation mode, when ammonia leaks from the engine body 2 or when the internal pressure of the engine body 2 rises and switches to the diesel operation mode (in case of emergency), the switching device 140 switches from the first discharge route F1 to the second discharge route F2 after a certain time after the switching. Even when switching from the ammonia operation mode to the diesel operation mode, due to blow-by remaining in the crankcase 70 (NH3: present), it can flow into the first discharge route F1 within a few minutes after the switching and be rendered harmless through the catalyst treatment device 60.

[0094] As described above, the reciprocating engine 1 of the present embodiment is a reciprocating engine 1 that uses ammonia as fuel, and includes: a cylinder 11 that forms a combustion chamber 10; an exhaust passage 30 that discharges exhaust gas from the combustion chamber 10; an exhaust gas treatment device (catalyst treatment device 60) that is provided in the exhaust passage 30 and treats unburned ammonia; a piston 12 that reciprocates within the cylinder 11; a crankshaft 13 that is connected to the piston 12; a crankcase 70 that houses the crankshaft 13, and blow-by gas flows from the combustion chamber 10 into the crankcase 70; and a suction device 110 that negatively suctions the inside of the crankcase 70. Among them, the unburned ammonia contained in the blow-by gas suctioned from the crankcase 70 by the suction device 110 is treated by the exhaust gas treatment device (catalyst treatment device 60). According to this structure, since the inside of the crankcase 70 can be negatively suctioned, it is possible to suppress the retention of ammonia within the reciprocating engine 1 and the leakage of ammonia to the surroundings of the reciprocating engine 1, thereby improving the safety of the reciprocating engine 1 that uses ammonia as fuel. As the exhaust gas treatment device, in addition to the catalyst treatment device 60, a gas scrubber or the like can also be used.

[0095] In addition, in the present embodiment, the exhaust gas treatment device is a catalyst treatment device 60 that uses a catalyst to treat unburned ammonia. If the catalyst treatment device 60 is used, there is no need for clean water or waste liquid treatment, and unburned ammonia can be treated well.

[0096] In addition, in the present embodiment, the suction device 110 includes a pressure gauge 113 that measures the pressure inside the crankcase 70, and a blower 111 that suctions the inside of the crankcase 70 into a negative pressure, pressurizes the suctioned gas, and pumps it into the exhaust passage 30. The blower 111 is driven such that the measurement result of the pressure gauge 113 becomes a specified value of negative pressure. According to this structure, even if the pressure of the exhaust passage 30 changes, the blower 111 is correspondingly driven to maintain the inside of the crankcase 70 at a specified value of negative pressure. As long as the inside of the crankcase 70 can be maintained at a negative pressure, the specified value of this negative pressure is preferably a negative pressure value close to 0, and it is preferably possible to set it within the range of 0 kPa > specified value ≥ -0.25 kPa.

[0097] In addition, in the present embodiment, the suction device 110 negatively suctions the inside of the crankcase 70 through a suction port 90 provided in a gas retention portion 16A that communicates with the inside of the crankcase 70. According to this structure, it is possible to suppress the blow-by gas from staying in the gas retention portion 16A.

[0098] In addition, in the present embodiment, the gas retention portion 16A is formed on the cylinder head 16. According to this structure, by negatively suctioning the blow-by gas from inside the cylinder head cover 17 (gas retention portion 16A), it is possible to suppress the blow-by gas from staying in the cover 17, and even when the operator opens the cover 17 during maintenance, safety can be ensured.

[0099] In addition, in the present embodiment, a gas inlet 92 is provided in the gas retention part 16A communicating with the inside of the crankcase 70, and the suction device 110 performs negative pressure suction on the inside of the crankcase 70 through the main suction port 75 provided at a position other than the gas retention part 16A where the gas inlet 92 is provided. According to this structure, by introducing external gas into the cover 17 (gas retention part 16A), blow-by gas is expelled from the inside of the cover 17, and it is possible to prevent blow-by gas from remaining in the cover 17.

[0100] In addition, in the present embodiment, there is a gas supply device 130 that supplies gas from the gas inlet 92 to the gas retention part 16A. According to this structure, by actively introducing gas into the cover 17 (gas retention part 16A), blow-by gas is expelled from the inside of the cover 17, and it is possible to prevent blow-by gas from remaining in the cover 17.

[0101] In addition, in the present embodiment, there are provided: a first discharge route F1 that connects the inside of the crankcase 70 to the exhaust passage 30 through the suction device 110, a second discharge route F2 that opens to the atmosphere without connecting the inside of the crankcase 70 to the exhaust passage 30, and a switching device 140 that switches between the first discharge route F1 and the second discharge route F2 according to the operating condition of the reciprocating engine 1. According to this structure, the discharge path of blow-by gas can be switched according to the presence or absence of unburned ammonia contained in the blow-by gas.

[0102] In addition, in the present embodiment, the reciprocating engine 1 can be switched between an ammonia operation mode (first operation mode) in which ammonia is contained in the fuel used and a diesel operation mode (second operation mode) in which a fuel other than ammonia such as heavy oil is used. The switching device 140 switches to the first discharge route F1 in the ammonia operation mode and switches to the second discharge route F2 in the diesel operation mode. In the ammonia operation mode, since unburned ammonia is contained in the blow-by gas, the blow-by gas can flow into the first discharge route F1, and after being made harmless by the catalyst treatment device 60, it is released to the atmosphere. In addition, in the diesel operation mode, since unburned ammonia is not contained in the blow-by gas, the blow-by gas can flow into the second discharge route F2 and be released to the atmosphere.

[0103] In addition, in the present embodiment, the switching device 140 switches from the first discharge route F1 to the second discharge route F2 after a certain time after switching from the ammonia operation mode to the diesel operation mode. According to this structure, even when switching from the ammonia operation mode to the diesel operation mode, since blow-by gas remains in the crankcase 70, in the few minutes after the switch, by flowing into the first discharge route F1, it can be made harmless by the catalyst treatment device 60.

[0104] Further, in the present embodiment, when the switching device 140 switches from the diesel operation mode to the ammonia operation mode, it immediately switches from the second discharge route F2 to the first discharge route F1. According to this structure, in the ammonia operation mode, since the blow-by gas contains unburned ammonia, the blow-by gas can immediately flow into the first discharge route F1 and be rendered harmless by the catalyst treatment device 60.

[0105] Further, in the present embodiment, an oil mist separator 120 is provided on the suction side of the suction device 110. According to this structure, the oil mist contained in the blow-by gas can be separated to protect the suction device 110.

[0106] As described above, the preferred embodiments of the present invention have been described and illustrated, but it should be understood that these embodiments are exemplary embodiments of the present invention and should not be considered as limitations. Additions, omissions, substitutions, and other changes can be made without departing from the scope of the present invention. As a preferred embodiment, a 4-stroke engine has been described as an example, but the same principle applies to a 2-stroke engine. Therefore, the present invention should not be considered as limited by the foregoing description, but by the claims.

[0107] For example, in Figure 6 In other embodiments shown, gas inlets 92 are provided in the gas retention portions 16A of each of the six cylinders 11, but gas inlets 92 may be provided in, for example, five of the six gas retention portions 16A, and a suction port 90 may be provided in one of the gas retention portions 16A. That is, as long as the suction device 110 can perform negative pressure suction on the crankcase 70 through the suction port 90 provided at a position other than the gas retention portion 16A provided with the gas inlet 92.

[0108] Further, for example, in the above embodiment, the suction device 110 has been described as a premise, but a method without the suction device 110 may also be adopted.

[0109] That is, the method shown in the appended note may be adopted.

[0110] 〈Appended Note〉 A reciprocating engine is a reciprocating engine that uses ammonia as fuel, comprising: a cylinder that forms a combustion chamber; an exhaust passage that discharges exhaust gas from the combustion chamber; a catalyst treatment device that is provided in the exhaust passage and uses a catalyst to treat unburned ammonia; a piston that reciprocates within the cylinder; a crankshaft that is connected to the piston; a crankcase that houses the crankshaft, and blow-by gas flows from the combustion chamber into the crankcase; a first discharge route that connects the inside of the crankcase to the exhaust passage; a second discharge route that does not connect the inside of the crankcase to the exhaust passage and opens the crankcase to the atmosphere; and a switching device that switches between the first discharge route and the second discharge route according to the operating condition of the reciprocating engine.

[0111] Symbol Explanation 1. Reciprocating engine 2. Engine body 3. Control device 4. Supercharger 10. Combustion chamber 11. Cylinder 12. Piston 13. Crankshaft 13a. Connecting rod 14. Rotation detection sensor 15. Torque detection sensor 16. Cylinder head 16A. Gas retention part 17. Cover 20. Intake passage 21. Intake valve 22. Compressor 23. Air cooler 24. Air heating device 25. Cooling and heating system 30. Exhaust passage 30a. Exhaust connection passage 30A. First exhaust path 30B. Second exhaust path 31. Exhaust valve 33. Turbine 34. Flow path switching valve 40. Ammonia fuel supply device 41. Ammonia tank 42. Vaporization device 43. Fuel gas injection valve 44. Ammonia supply line 44a. Regulator 44b. Pressure sensor 45. Second ammonia supply line 45a, Regulator 45b, Pressure Sensor 50, Liquid Auxiliary Fuel Supply Device 51, Liquid Auxiliary Fuel Tank 52, First Liquid Fuel Supply Pump 53, Liquid Fuel Injection Valve 54, Second Liquid Fuel Supply Pump 55, Ignition Device 60, Catalyst Treatment Device (Exhaust Treatment Device) 60a, Detection Sensor 61, First Treatment Tank 62, Second Treatment Tank 70, Crankcase 71, Oil Pan 72, Crankcase Chamber 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 Pipe 92, Gas Inlet 93, Gas Inlet Pipe 100, Suction Path 101, First Discharge Path 102, Second Discharge Path 103, Symbol 110, Suction Device 111, Blower 112, Electric Motor 113, Pressure Gauge 114, Inverter 120, Oil Mist Separator 121, First Separation Section 122, Second Separation Section 123, Differential Pressure Gauge 124, Return Flow Path 130, Gas Supply Device 131, Gas Supply Path 140, Switching Device F1, First Discharge Route F2, Second Discharge Route.

Claims

1. A reciprocating engine that uses ammonia as fuel, comprising: A cylinder that forms a combustion chamber; An exhaust passage that discharges exhaust gas from the combustion chamber; An exhaust treatment device that is provided in the exhaust passage and treats unburned ammonia; A piston that reciprocates within the cylinder; A crankshaft that is connected to the piston; A crankcase that houses the crankshaft, and blow-by gas flows from the combustion chamber into the crankcase; and A suction device that negatively suctions the inside of the crankcase, wherein the exhaust treatment device treats unburned ammonia contained in the blow-by gas suctioned from the crankcase by the suction device.

2. The reciprocating engine according to claim 1, wherein The exhaust treatment device is a catalyst treatment device that uses a catalyst to treat unburned ammonia.

3. The reciprocating engine according to claim 2, wherein The suction device has a pressure gauge that measures the pressure inside the crankcase, and a blower that suctions the inside of the crankcase to a negative pressure, pressurizes the suctioned gas, and discharges it to the exhaust passage, and the blower is driven such that the measurement result of the pressure gauge becomes a specified value of negative pressure.

4. The reciprocating engine according to claim 3, wherein The suction device negatively suctions the inside of the crankcase through a suction port provided in a gas retention portion communicating with the inside of the crankcase.

5. The reciprocating engine according to claim 4, wherein The gas retention portion is formed on the cylinder head.

6. The reciprocating engine according to claim 3, wherein A gas inlet is provided in the gas retention portion communicating with the inside of the crankcase, and the suction device negatively suctions the inside of the crankcase through a suction port provided at a position other than the gas retention portion provided with the gas inlet.

7. The reciprocating engine according to claim 6, comprising: A gas supply device that supplies gas from the gas inlet to the gas retention portion.

8. The reciprocating engine according to any one of claims 1 to 7, comprising: A first discharge route that connects the inside of the crankcase to the exhaust passage through the suction device; A second discharge route that does not connect the inside of the crankcase to the exhaust passage and opens the inside of the crankcase to the atmosphere; and A switching device that switches between the first discharge route and the second discharge route according to the operating condition of the reciprocating engine.

9. The reciprocating engine according to claim 8, wherein The reciprocating engine can be switched to a first operating mode in which the fuel in use contains ammonia and a second operating mode in which a fuel other than ammonia is used, The switching device switches to the first discharge route in the first operating mode, and the switching device switches to the second discharge route in the second operating mode.

10. The reciprocating engine according to claim 9, wherein The switching device switches from the first discharge route to the second discharge route a certain time after switching from the first operating mode to the second operating mode.

11. The reciprocating engine according to claim 9, wherein When the switching device switches from the second operation mode to the first operation mode, it immediately switches from the second discharge route to the first discharge route.

12. The reciprocating engine according to any one of claims 1 to 7, wherein an oil mist separator is provided on the suction side of the suction device.

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