Marine engines

Abstract

To provide a marine engine which is used in a scene in which a marine vessel cruises in a sea area at a high load, and in the scene in which the marine vessel cruises in the sea area at a low load, and which can enhance a ratio of alternate fuel such as an ammonia to enhance a so-called "mixed fuel combustion rate" in the scene in which the marine vessel cruises in the sea area at the high load, and enhance exhaust gas performance by suppressing the generation of a nitrogen oxide (NOx) in the scene in which the marine vessel cruises in the sea area at the low load.SOLUTION: When it is determined that a sea area in which a marine vessel exists is a sea area in which the marine vessel cruises at a high load, an engine 1 is operated at a mixed fuel combustion mode in S3. After that, a step is transited to S4, and combustion chamber temperature raising means is operated. Meanwhile, when it is determined that the sea area in which the marine vessel exists is a sea area in which the marine vessel cruises at a low load, the engine 1 is operated at a normal combustion mode in S5. After that, the step is transited to S6, and the combustion chamber temperature raising means is stopped.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a marine engine for use in ships, and more particularly to a marine engine capable of burning alternative fuels such as ammonia together with conventional fossil fuels. [Background technology]

[0002] In recent years, due to the problems of global warming, greenhouse gases such as carbon dioxide have become There is a demand for the realization of zero emissions, which means reducing carbon dioxide (CO2) emissions to zero. Therefore, alternative fuels such as ammonia, which do not emit greenhouse gases such as carbon dioxide when burned, are attracting attention. However, alternative fuels such as ammonia are harder to burn than fossil fuels, making it difficult to achieve "single-combustion" in which only ammonia is burned.

[0003] Therefore, so-called "mixed combustion" marine engines, which burn ammonia or the like together with fossil fuels such as diesel fuel, have been considered.

[0004] For example, Patent Document 1 below discloses a combustion engine that uses a fuel injection valve that injects fossil fuel and alternative fuel in layers to mix and burn fossil fuel and alternative fuel, and injects the fossil fuel and alternative fuel into a combustion chamber from this fuel injection valve.

[0005] In the technology of Patent Document 1, for example, when a fossil fuel is used as a pilot fuel for ignition and an alternative fuel is used as the main fuel, the two fuels are injected into a combustion chamber to be mixed and burned. In order to avoid this, if the amount of alternative fuel is increased, unburned alternative fuel will remain. Therefore, a fossil fuel is further interposed between the alternative fuels to improve ignition performance, thereby achieving complete mixed combustion.

[0006] On the other hand, Patent Document 2 below also proposes that in an engine that burns ammonia exclusively, compressed heated gas is sent to increase the temperature of the combustion chamber in order to promote the combustion of the ammonia. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-180567 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-202559 Summary of the Invention [Problem to be solved by the invention]

[0008] Recently, as the required reduction amount of greenhouse gases has been further increased, there is a demand to increase the amount of alternative fuel and increase the ratio of alternative fuel in one fuel injection, that is, the so-called "mixed combustion ratio," even when alternative fuels are mixed, as in Patent Document 1. However, simply increasing the mixed combustion ratio could result in an increase in unburned residue of alternative fuels such as ammonia, because alternative fuels such as ammonia are difficult to burn, and this has led to the problem that the limit of the mixed combustion ratio cannot be exceeded.

[0009] Therefore, as described in Patent Document 2, it is conceivable to operate an engine that co-fuels ammonia or other alternative fuels by increasing the temperature of the combustion chamber to promote the combustion of the ammonia. In this way, by increasing the temperature of the combustion chamber, it is conceivable to reduce the amount of unburned ammonia or other alternative fuel and increase the co-fuel ratio even in a marine engine that co-fuels ammonia or other alternative fuels.

[0010] However, ships do not always operate their engines at a constant load, but rather operate them at a low load when they are close to land, such as when entering or leaving a port. In such situations, the combustion of alternative fuels such as ammonia deteriorates, so it is possible to stop co-firing with alternative fuels and operate the engine solely on fossil fuels such as diesel.

[0011] However, if the engine is operated by burning only fossil fuels while keeping the temperature of the combustion chamber high, nitrogen oxides (NOx) will be generated, which will cause a deterioration in exhaust gas performance.

[0012] The present invention has been made in view of the above points, and its purpose is to provide a marine engine that can be used in both high-load and low-load sea navigation, and that can increase the ratio of alternative fuel such as ammonia to increase the so-called "mixed-fuel ratio" when navigating in sea areas under high load, while suppressing the generation of nitrogen oxides (NOx) and improving exhaust gas performance when navigating in sea areas under low load. [Means for solving the problem]

[0013] To achieve this object, the present invention provides: The ship Scenes of sailing through the seas under high load, The ship This marine engine is used when sailing in sea areas at low load, and is characterized in that when sailing in sea areas at high load, it operates in a mixed combustion mode in which both alternative fuel and fossil fuel are burned, and a combustion chamber temperature increasing means is activated to increase the combustion chamber temperature, and when sailing in sea areas at low load, it operates in a normal combustion mode in which fossil fuel is burned, and the combustion chamber temperature increasing means is controlled not to be activated.

[0014] Specifically, in the first invention, The ship Scenes of sailing through the seas under high load, The shipA marine engine for use in situations where the ship is navigating in sea areas at low load, the engine having a combustion mode selection means which has a dual-combustion mode in which both alternative fuel and fossil fuel are injected into the combustion chamber and burned, and a normal combustion mode in which fossil fuel is injected into the combustion chamber and burned, and a combustion chamber temperature increasing means which increases the temperature of the combustion chamber, wherein, in situations where the ship is navigating in sea areas at high load, the combustion mode selection means selects the dual-combustion mode and activates the combustion chamber temperature increasing means to control so as to increase the temperature of the combustion chamber, and when the ship is navigating in sea areas at low load, the engine has engine control means which selects the normal combustion mode with the combustion mode selection means and stops the combustion chamber temperature increasing means to control so as not to increase the temperature of the combustion chamber.

[0015] With this configuration, when the ship is sailing in an area with a high load, the combustion mode selection means selects the dual-fuel mode and controls the combustion chamber temperature increasing means to operate, while when the ship is sailing in an area with a low load, the combustion mode selection means selects the normal combustion mode and controls the combustion temperature increasing means to stop. In other words, when the engine is operating in the dual-fuel mode, the temperature in the combustion chamber increases, but when the engine is operating in the normal combustion mode, the temperature in the combustion chamber does not increase.

[0016] Therefore, in dual combustion mode, the temperature in the combustion chamber rises, so even if a larger amount of alternative fuel is injected, the alternative fuel does not remain unburned, and greenhouse gas (especially carbon dioxide) emissions can be reduced.On the other hand, in normal combustion mode, the temperature in the combustion chamber does not rise, so the generation of nitrogen oxides (NOx) can be reduced.

[0017] Here, "fossil fuel" refers to general fuels that can be refined from crude oil, such as diesel fuel, distillate oil, and residual oil. On the other hand, "alternative fuel" refers to fuels that can replace natural petroleum, such as ammonia, biofuel, methanol, and ethanol, which can be used as a substitute for petroleum.

[0018] "Dual-fuel mode" refers to an engine combustion mode in which fossil fuel and alternative fuel are injected into the combustion chamber and burned together. Note that a single fuel injector may inject both fuels, or multiple fuel injectors may inject the fuels separately.

[0019] Furthermore, "normal combustion mode" refers to the combustion mode of an engine in which only fossil fuel is injected into the combustion chamber and the fossil fuel is burned.

[0020] In a second aspect of the present invention, the combustion chamber temperature increasing means is a scavenging air temperature increasing means that increases the temperature of the scavenging air introduced into the combustion chamber.

[0021] According to this configuration, since the combustion chamber temperature increasing means is a scavenging air temperature increasing means that increases the temperature of the scavenging air introduced into the combustion chamber, the temperature of the scavenging air introduced into the combustion chamber is higher than in the normal combustion mode.

[0022] Therefore, since the temperature of the introduced scavenging air itself is high, the temperature of the combustion chamber also inevitably rises, making it easier for the alternative fuel to ignite and burn.

[0023] Therefore, the combustibility of the alternative fuel in the multi-combustion mode can be more reliably improved.

[0024] In a third aspect of the present invention, the scavenging air temperature increasing means is an air cooler cooling water flow rate limiting mechanism that limits the flow rate of cooling water in an air cooler that cools the scavenging air.

[0025] According to this configuration, the scavenging air temperature increasing means is an air cooler cooling water flow rate limiting mechanism that limits the flow rate of cooling water in the air cooler that cools the scavenging air, so the cooling performance of the air cooler can be reduced and the temperature of the scavenging air introduced into the combustion chamber can be increased.

[0026] Therefore, by the simple method (structure) of restricting the flow rate of the cooling water of the air cooler, the temperature of the scavenging air can be increased, and the temperature of the combustion chamber can be increased.

[0027] Therefore, the scavenging air temperature increasing means can be configured with a simple method (structure), and the ratio of the alternative fuel in the mixed combustion can be increased.

[0028] In a fourth aspect of the present invention, the scavenging air temperature increasing means is an air cooler coolant temperature increasing mechanism that increases the temperature of coolant in an air cooler that cools the scavenging air.

[0029] According to this configuration, the scavenging air temperature increasing means is an air cooler coolant temperature increasing mechanism that increases the temperature of the coolant in the air cooler that cools the scavenging air, so that the cooling performance of the air cooler can be reduced and the temperature of the scavenging air can be increased without changing the flow rate of the coolant flowing through the air cooler.

[0030] Therefore, the temperature of the scavenging air can be increased and the temperature of the combustion chamber can be increased without reducing the flow rate of the cooling water flowing through the air cooler.

[0031] This allows the flow rate of cooling water in the air cooler to be kept constant at all times, reducing the risk of air cooler failure. Also, the ratio of alternative fuels used in mixed combustion can be increased.

[0032] In a fifth aspect of the present invention, the combustion chamber temperature increasing means is an engine cylinder coolant flow rate limiting mechanism that limits the flow rate of coolant that cools the engine cylinder.

[0033] According to this configuration, the combustion chamber temperature increasing means is an engine cylinder coolant flow rate limiting mechanism that limits the flow rate of the coolant that cools the engine cylinder. Therefore, the flow rate of the coolant that cools the engine cylinder is limited, and the temperature of the engine cylinder increases, thereby increasing the temperature of the combustion chamber provided in that engine cylinder.

[0034] Therefore, the temperature of the combustion chamber can be increased by the simple method (structure) of restricting the flow rate of the cooling water that cools the engine cylinder.

[0035] Therefore, by using a simple method (structure) of restricting the flow rate of cooling water in the engine cylinder, it is possible to configure a means for increasing the combustion temperature and also to increase the ratio of alternative fuels in mixed combustion.

[0036] In a sixth aspect of the present invention, the combustion chamber temperature increasing means is an exhaust valve advance mechanism that advances the closing timing of the exhaust valve.

[0037] According to this configuration, the combustion chamber temperature increasing means is an exhaust valve advance mechanism that advances the closing timing of the exhaust valve, thereby accelerating the closing timing of the exhaust valve. This lengthens the period during which the air is compressed by the piston. This lengthens the compression period, which increases the air temperature, and as a result, increases the temperature of the combustion chamber.

[0038] Therefore, by using a method (structure) to advance the closing timing of the exhaust valve, the period during which the air is compressed can be lengthened, thereby increasing the temperature in the combustion chamber.

[0039] Therefore, the combustion chamber temperature increasing means can be configured without affecting the engine's cooling system, and the ratio of alternative fuels in mixed combustion can be increased.

[0040] In a seventh aspect of the present invention, the combustion chamber temperature increasing means is a hot bulb communication mechanism that communicates the combustion chamber with a hot bulb chamber in which a hot bulb, which is a heat source, is disposed.

[0041] According to this configuration, the combustion chamber temperature increasing means is a hot bulb connection mechanism that connects the combustion chamber with the hot bulb chamber in which the hot bulb, which is a heat source, is placed, so that when the hot bulb connection mechanism is activated, the air in the combustion chamber is heated by the hot bulb, which is a heat source.

[0042] This ensures that the temperature in the combustion chamber rises, allowing for a higher mixed combustion ratio of alternative fuels.

[0043] Therefore, the combustion chamber temperature can be reliably increased, and the mixed combustion ratio, which is the ratio of alternative fuels, can be increased. [Effects of the Invention]

[0044] As explained above, according to the present invention, in the dual combustion mode, the temperature of the combustion chamber rises, so even if a larger amount of alternative fuel is injected, the alternative fuel does not remain unburned, and the emission of greenhouse gases (especially carbon dioxide) can be reduced. On the other hand, in the normal combustion mode, the temperature of the combustion chamber does not rise, so the generation of nitrogen oxides (NOx) can be reduced.

[0045] Therefore, this is a marine engine that can be used in situations where the ship is navigating in sea areas at high load and situations where the ship is navigating in sea areas at low load.When the ship is navigating in sea areas at high load, the ratio of alternative fuel such as ammonia can be increased to increase the so-called "mixed combustion ratio," while when the ship is navigating in sea areas at low load, the generation of nitrogen oxides (NOx) can be suppressed and exhaust gas performance can be improved. [Brief explanation of the drawings]

[0046] [Figure 1] 1 is a schematic diagram illustrating the configuration of a marine engine according to a first embodiment of the present invention. [Figure 2] 1 is a system schematic diagram showing the system configuration of a fuel injection device according to a first embodiment. [Figure 3] FIG. 2 is a detailed longitudinal sectional view showing a combustion chamber of a marine engine. [Figure 4] 1 is a schematic diagram of an intake and exhaust system and a cooling system of a marine engine according to a first embodiment. [Figure 5] 3 is a main control flowchart according to the first embodiment. [Figure 6] 4 is a sub-control flowchart according to the first embodiment. [Figure 7] FIG. 10 is a schematic diagram of an intake and exhaust system and a cooling system of a marine engine according to a second embodiment. [Figure 8] 10 is a sub-control flowchart according to the second embodiment. [Figure 9] FIG. 10 is a schematic diagram of an intake and exhaust system and a cooling system of a marine engine according to a third embodiment. [Figure 10]10 is a sub-control flowchart according to the third embodiment. [Figure 11] FIG. 10 is a schematic diagram of an intake and exhaust system and a cooling system of a marine engine according to a fourth embodiment. [Figure 12] 10 is a sub-control flowchart according to the fourth embodiment. [Figure 13] FIG. 10 is a schematic diagram illustrating the configuration of a marine engine according to a fifth embodiment. [Figure 14] FIG. 10 is a system schematic diagram showing an exhaust valve device according to a fifth embodiment. [Figure 15] 10 is a control flowchart of an exhaust valve device according to a fifth embodiment. [Figure 16] 10 is a sub-control flowchart according to the fifth embodiment. [Figure 17] FIG. 10 is a schematic diagram showing the configuration of a marine engine according to a sixth embodiment. [Figure 18] 13 is a sub-control flowchart according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0047] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0048] (Embodiment 1) FIG. 1 is a schematic diagram showing the configuration of a marine engine for ships, FIG. 2 is a system schematic showing the system configuration of a fuel injection device, FIG. 3 is a detailed longitudinal cross-sectional view showing the combustion chamber of the marine engine, and FIG. 4 is a schematic diagram of the intake and exhaust system and cooling system of the marine engine. Using these figures, we will first provide an overview of the marine engine 1. Hereinafter, the marine engine 1 for ships will be simply referred to as "engine 1."

[0049] The engine 1 is an in-line multi-cylinder marine engine equipped with multiple cylinders 10. For convenience, only one cylinder will be shown in the present embodiment. The engine 1 is configured as a two-stroke, one-cycle engine that employs a uniflow scavenging system, and is installed on large ships such as tankers, container ships, and car carriers.

[0050] An engine 1 mounted on a ship is used as a main engine for propelling the ship. That is, the output shaft of the engine 1 is connected to a propeller (not shown) of the ship via a propeller shaft (not shown). When the engine 1 is operated, its output is transmitted to the propeller, thereby propelling the ship.

[0051] In particular, the engine 1 according to this embodiment is configured as a so-called crosshead type internal combustion engine in order to achieve a long stroke. That is, in this engine 1, a piston rod 22 that supports a piston 21 from below and a connecting rod 24 that is connected to a crankshaft 23 are connected by a crosshead 25.

[0052] The engine 1 also includes a base plate 11 located below, a frame 12 provided on the base plate 11, and a cylinder jacket 13 provided on the frame 12. The base plate 11, frame 12, and cylinder jacket 13 are fastened together by a plurality of tie bolts B extending in the vertical direction and nuts. The engine 1 also includes a cylinder 10 provided within the cylinder jacket 13, a piston 21 provided within the cylinder 10, and an output shaft (e.g., crankshaft 23) that rotates in conjunction with the reciprocating motion of the piston 21.

[0053] The base plate 11 constitutes the so-called crankcase of the engine 1 and houses a crankshaft 23 and a bearing 26 that rotatably supports the crankshaft 23. The lower end of a connecting rod 24 is connected to the crankshaft 23 via a crank 27.

[0054] The frame 12 houses a pair of guide plates 28, 28, the connecting rod 24, and a crosshead 25. Of these, the pair of guide plates 28, 28 are made of a pair of plate-shaped members provided along the piston axial direction, and are arranged at a distance from each other in the width direction of the engine 1 (the left-right direction on the paper surface of FIG. 1 ). The connecting rod 24 is arranged between the pair of guide plates 28, 28, with its lower end connected to the crankshaft 23. The upper end of the connecting rod 24 is connected to the lower end of the piston rod 22 via the crosshead 25.

[0055] Specifically, the crosshead 25 is disposed between a pair of guide plates 28, 28 and slides up and down along the guide plates 28, 28. That is, the pair of guide plates 28, 28 are configured to guide the sliding of the crosshead 25. The crosshead 25 is connected to the piston rod 22 and the connecting rod 24 via a crosshead pin 29. The crosshead pin 29 is connected to the piston rod 22 so as to move up and down integrally therewith, and is connected to the connecting rod 24 so as to rotate the connecting rod 24 around the upper end of the connecting rod 24 as a fulcrum.

[0056] The cylinder jacket 13 has a cylinder liner 14 disposed therein as an inner cylinder. The piston 21 described above is disposed inside the cylinder liner 14. The piston 21 reciprocates up and down along the inner wall of the cylinder liner 14. A cylinder cover 15 is fixed to the top of the cylinder liner 14. The cylinder cover 15 and the cylinder liner 14 constitute the cylinder 10.

[0057] Additionally, the cylinder cover 15 is provided with an exhaust valve 18 that is operated by an exhaust valve device (not shown in FIG. 1). The exhaust valve 18, together with the cylinder 10, which is made up of the cylinder liner 14 and the cylinder cover 15, and the top surface of the piston 21, defines a combustion chamber 17. The exhaust valve 18 opens and closes the connection between the combustion chamber 17 and an exhaust pipe 19. The exhaust pipe 19 has an exhaust port (not shown) that communicates with the combustion chamber 17, and the exhaust valve 18 is configured to open and close the exhaust port.

[0058] The cylinder cover 15 also defines the ceiling surface of the combustion chamber 17. A fuel injection valve 30 is provided on this ceiling surface.

[0059] As shown in Fig. 3, this fuel injection valve 30 is provided in a position facing the interior of the combustion chamber 17, and has an injection port 31 that injects fossil fuel and alternative fuel, or fossil fuel only. For convenience, Fig. 3 shows one fuel injection valve 30, but in this embodiment, three fuel injection valves 30 are provided for each cylinder.

[0060] Specifically, the fuel injection valve 30 is arranged with its injection port 31 facing the combustion chamber 17, and is configured to inject fuel in layers with the fossil fuel and alternative fuel arranged alternately. do.

[0061] Here, the alternative fuel functions as the main fuel that generates power for the engine 1, and the fossil fuel functions as a pilot fuel for igniting the main fuel. In this embodiment, diesel fuel is used as the fossil fuel, and ammonia is used as the alternative fuel. Therefore, the alternative fuel according to this embodiment has a higher ignition temperature at which compression ignition occurs than fossil fuel.

[0062] Although not specifically shown, there are cases where the fuel injection valve 30 injects only fossil fuel without using alternative fuel. In this case, as is well known, the fossil fuel is injected into the combustion chamber in a single layer.

[0063] A fuel injection device 100 that supplies fuel to the fuel injection valve 30 will be described later with reference to FIG.

[0064] In this way, the fuel injection valve 30 injects the fossil fuel and the alternative fuel into the combustion chamber 17, and both are combusted within the combustion chamber 17. The combustion of the fossil fuel and the alternative fuel within the combustion chamber 17 is called "mixed combustion." Details of "mixed combustion" will be described later.

[0065] This combustion causes a piston 21 shown in Fig. 1 to reciprocate up and down. At this time, when the exhaust valve 18 operates to open the combustion chamber 17, exhaust gas generated by the combustion is pushed out into the exhaust pipe 19, and scavenging air is introduced into the combustion chamber 17 from a scavenging port (not shown) provided below.

[0066] Furthermore, when the piston 21 reciprocates due to this combustion, the piston rod 22 reciprocates up and down together with the piston 21. This causes the crosshead 25 connected to the piston rod 22 to reciprocate up and down. This crosshead 25 allows the connecting rod 24 to rotate, and causes the connecting rod 24 to rotate around the connection point with the crosshead 25 as a fulcrum. Then, the crank 27 connected to the lower end of the connecting rod 24 performs crank motion, and the crankshaft 23 rotates in response to this crank motion. In this way, the crankshaft 23 converts the reciprocating motion of the piston 21 into rotational motion, and rotates the ship's propeller together with the propeller shaft. This propels the ship.

[0067] Next, a fuel injection device 100 that supplies fuel to the fuel injection valve 30 will be described with reference to FIG.

[0068] This fuel injection device 100 includes a fuel pump 41 that pumps fossil fuel to the fuel injection valve 30, and an injection pump 51 that injects alternative fuel into the path through which the fossil fuel is pumped.

[0069] The fuel pump 41 and the injection pump 51 are disposed near the cylinder 10 as shown in FIG. 1, and are connected to the fuel injection valve 30 via the first internal passage 32, the fuel injection pipe 42, the second internal passage 33, the injection pipe 52, etc.

[0070] Of these, the fuel pump 41 is connected to the fuel injection valve 30 via a fossil fuel path L that runs from the fuel pump 41 to the injection port 31, and pumps fossil fuel toward the fuel injection valve 30. The fossil fuel path L is made up of a first internal path 32 and a fuel injection pipe 42 (including a branch pipe 42a, etc., which will be described later), and is configured as a path that connects the fuel pump 41 and the injection port 31.

[0071] The injection pump 51 is connected to the fossil fuel path L via the second internal path 33 and an injection pipe 52, and injects the alternative fuel into the fossil fuel path L.

[0072] With this configuration, the fuel injection valve 30 can inject the fossil fuel pumped by the fuel pump 41 and the alternative fuel injected by the injection pump 51 into the combustion chamber 17 in a stratified manner.

[0073] As described above, the engine of this embodiment is provided with three fuel injection valves 30 for each cylinder. Therefore, in order to supply fossil fuel and alternative fuel to each fuel injection valve 30, the fuel injection pipe 42 and the injection pipe 52 are branched into three branch pipes (42a, 42b, 42c, 52a, 52b, 52c) via branch portions 43 and 53, respectively.

[0074] Furthermore, the fuel pump 41 that pumps fossil fuel into the fuel injection pipe 42 and the injection pump 51 that injects alternative fuel into the injection pipe 52 are controlled by the control unit 92. Specifically, the fuel control valve 45 and the injection control valve 55 are controlled by control signals sent from the control unit 92, thereby controlling the operation of the fuel pump 41 and the injection pump 51.

[0075] A detection unit 91 that detects various signals such as the engine crank angle is connected to this control unit 92, and the control unit 92 is configured to control the operation of the fuel pump 41 and the injection pump 51 based on the various signals detected by this detection unit 91. Note that the dashed lines in Fig. 2 indicate electrical connections.

[0076] The fuel pump 41 is connected to a fuel tank (not shown) that stores fossil fuel through piping or the like (not shown), and is configured to receive fossil fuel from this fuel tank.

[0077] On the other hand, an alternative fuel supply pump 71 that supplies alternative fuel is connected to the injection pump 51 through a supply pipe 72, so that the alternative fuel is supplied. The alternative fuel supply pump 71 is also connected through piping or the like (not shown) to an alternative fuel tank (not shown) in which alternative fuel is stored, so that the alternative fuel is received from the alternative fuel tank.

[0078] In addition, a pressure accumulator 81 is connected to the fuel pump 41 and the injection pump 51. This pressure accumulator 81 accumulates pressure of the hydraulic oil that operates the fuel pump 41 and the injection pump 51. The pressure accumulator 81 is connected to a high-pressure pump 82, and is configured to store and accumulate pressure of the hydraulic oil that is pressure-fed from the high-pressure pump 82.

[0079] The alternative fuel path (supply pipe 72, injection pipe 52, second internal path 33) through which the alternative fuel is injected is provided with check valves 73, 54, 34 at respective locations to prevent backflow of the alternative fuel.

[0080] With the fuel injection device 100 configured as described above, in the engine 1 of this embodiment, when the ship is sailing in an area of ​​sea under high load, as will be described later, the control unit 92 operates in a so-called "mixed combustion mode" in which both fossil fuel and alternative fuel are injected into the combustion chamber 17 from the fuel injection valves 30, and mixed combustion occurs in the combustion chamber 17.

[0081] On the other hand, when the ship is sailing in the sea area at low load, the control unit 92 stops the operation of the alternative fuel injection pump 51, and only fossil fuel is injected into the combustion chamber 17 from the fuel injection valves 30..., so that the ship operates in the so-called "normal combustion mode," and normal combustion occurs in the combustion chamber 17.

[0082] Next, the intake and exhaust system and the cooling system of the engine 1 of this embodiment will be described with reference to FIG.

[0083] The intake and exhaust system AL of the engine 1 is configured to include a turbocharger 101 that takes in outside air from the upstream side and compresses the air, an air cooler 102 that cools the compressed air, a drain separator 103 that removes condensed water from the cooled air, a scavenging chamber 104 that stores compressed air before scavenging (introducing) it into the combustion chamber 17, the combustion chamber 17 provided in the cylinder jacket 13, an exhaust pipe 105 that guides exhaust gas discharged from the combustion chamber 17 downstream, and an exhaust path 106 that guides the exhaust gas guided to the exhaust pipe 105 back to the turbocharger 101.

[0084] By configuring the intake and exhaust system AL of the engine 1 in this way, fresh outside air is compressed once by the turbocharger 101, increasing the air density before being sent to the engine 1 side. Of course, when air is compressed, the air temperature rises, so this compressed air is cooled by the air cooler 102. However, when the compressed air is cooled, condensed water (drain) is generated, so this condensed water is removed by a drain separator 103 provided downstream. The compressed air from which the condensed water has been removed is stored in a scavenging chamber 104, and this compressed air scavenges the combustion chamber 17 of the cylinder jacket 13 from the scavenging chamber 104.

[0085] After the fuel is combusted in the combustion chamber 17 using the compressed air, the exhaust gas is scavenged with compressed air from the next cycle and collected in an exhaust pipe 105. The collected exhaust gas is guided to the turbocharger 101 through an exhaust path 106, activates the turbocharger 101, and is then discharged to the outside.

[0086] The cooling system for Engine 1 consists of two systems: a high-temperature cooling system HCL and a low-temperature cooling system LCL.

[0087] The high-temperature cooling system HCL is a system that cools the cylinder jacket 13 of the engine 1, and is equipped on the path of this high-temperature cooling system HCL with a seawater heat exchanger 107 that uses seawater to cool fresh water cooling water, and a pump device 108 that circulates the fresh water cooling water through the path of the high-temperature cooling system HCL. Note that the high-temperature cooling system HCL is also provided with a bypass path 109 that does not pass through the seawater heat exchanger 107.

[0088] In this high-temperature cooling system HCl, fresh water, which is cooling water flowing through the pathway of the high-temperature cooling system HCl, is cooled in a seawater heat exchanger 107, and the cooled fresh water is sent into the cylinder jacket 13 of the engine 1 using a pump device 108. The fresh water sent into the cylinder jacket 13 flows inside the cylinder jacket 13, thereby removing heat held by the cylinder jacket 13 and cooling it.

[0089] On the other hand, the low-temperature cooling system LCL is a system that cools the air cooler 102 that cools the engine intake air (compressed air), and is equipped on the path of the low-temperature cooling system LCL with a seawater heat exchanger 110 that uses seawater to cool the fresh water or seawater that serves as cooling water, and a pump device 101 that circulates the fresh water or seawater that serves as cooling water through the path of the low-temperature cooling system LCL.

[0090] The low-temperature cooling system LCL is also provided with a bypass path 112 that bypasses the air cooler 102. A bypass valve 113 and a restriction valve 114 are provided midway along the bypass path 112 and near the inlet of the air cooler 102, respectively. The bypass valve 113 and the restriction valve 114 are configured to be switchably controlled in response to signals from the control unit 92.

[0091] In this low-temperature cooling system LCL, fresh water or seawater, which is cooling water flowing through this path, is sent to a seawater heat exchanger 110 using a pump device 111, and the fresh water or seawater, which is cooling water, is cooled in the seawater heat exchanger 110, and the cooled fresh water or seawater is sent to an air cooler 102. The fresh water or seawater sent into the air cooler 102 cools the compressed air whose temperature has risen.

[0092] Furthermore, this low-temperature cooling system LCL is configured to change the flow path of the fresh water or seawater cooling water by controlling the bypass valve 113 and the restriction valve 114, thereby changing the cooling performance of the air cooler 102. That is, by opening the bypass valve 113 and closing the restriction valve 114, the fresh water or seawater cooling water flows into the bypass path 112 and does not flow into the air cooler 102, thereby reducing the cooling performance of the air cooler 102 and preventing the compressed air passing through the air cooler 102 from being cooled.

[0093] In this manner, in this embodiment, the cooling performance of the air cooler 102 is changed and the temperature of the compressed air is changed by controlling the bypass valve 113 and the restriction valve 114. Note that the bypass valve 113 and the restriction valve 114 may be controlled to be partially open or partially closed, thereby finely adjusting the amount of cooling water flowing into the air cooler 102.

[0094] The control unit 92 shown in FIG. 4 is configured to send control signals to the fuel pump 41 that pumps the fossil fuel to each of the fuel injection valves 30, and to the injection pump 51 that pumps the alternative fuel.

[0095] The present embodiment configured as above is controlled in accordance with the main control flowchart shown in FIG. 5 and the sub-control flowchart shown in FIG.

[0096] First, as shown in FIG. 5, in S1, the control unit 92 of this engine 1 reads various information (various signals) necessary for engine control from the detection unit 91, such as the current location of the ship from GPS signals, the operating status of the ship, and even the pilot's driving information.

[0097] Next, in S2, based on information such as the ship's current location, it is determined whether the current sea area is one in which the ship is sailing under high load. Specifically, if the area is not close to land, such as when entering or leaving a port, it is determined whether the ship is sailing under high load.

[0098] If S2 determines that the area is one where high loads will be applied, the process moves to S3. If S2 determines that the area is not one where high loads will be applied, the process moves to S5.

[0099] If it is determined that the sea area where the ship is currently located is an area where high loads are expected to be navigated, the engine 1 is operated in a mixed combustion mode in S3. That is, both the fossil fuel and the alternative fuel are injected from the fuel injection valve 30 into the combustion chamber 17, and the fossil fuel and the alternative fuel are mixed and burned in the combustion chamber 17. Specifically, the fuel pump 41 and the injection pump 51 are operated, and the fossil fuel and the alternative fuel are injected in layers from the fuel injection valve 30 into the combustion chamber 17, and the fossil fuel and the alternative fuel are mixed and burned in the combustion chamber 17.

[0100] Thereafter, the process proceeds to S4, where the combustion chamber temperature increasing means is activated. The control flow for the operation of this combustion chamber temperature increasing means will be explained later with reference to FIG. 6(a).

[0101] Then, the process returns to prepare for the next control cycle.

[0102] On the other hand, if the current location of the ship is not an area where high loads are expected to be navigated, the engine 1 is operated in normal combustion mode in S5. That is, only fossil fuel is injected from the fuel injection valve 30 into the combustion chamber 17, and only fossil fuel is burned in the combustion chamber 17. Specifically, only the fuel pump 41 is operated, and only fossil fuel is injected in a single layer from the fuel injection valve 30 into the combustion chamber 17, and the combustion In the kiln 17, only fossil fuels are burned.

[0103] Thereafter, the process proceeds to S6, where the combustion chamber temperature increasing means is stopped. This control flow for stopping the combustion chamber temperature increasing means will also be explained later with reference to Figure 6(b).

[0104] Finally, the process returns to prepare for the next control cycle.

[0105] In this embodiment, in S2, it is determined whether the ship is currently operating in an area where it is under high load based on information such as the ship's current location. However, if the pilot operates the engine in a way that puts it under high load, it may be determined that the ship is operating under high load based on that operation information, and the process may proceed to S3.

[0106] Next, the activation and deactivation of the combustion chamber temperature increasing means will be described with reference to the sub-control flow in Fig. 6. Note that the combustion chamber temperature increasing means of the first embodiment will be referred to as "combustion chamber temperature increasing means (1)" below.

[0107] As shown in Figure 6(a), the combustion chamber temperature increasing means (1) operates in S11 to open the bypass valve 113 of the bypass path 112 of the air cooler 102. Then, in S12, the restriction valve 114 that restricts the amount of cooling water in the air cooler 102 is closed. In other words, the bypass valve 113 and the restriction valve 114 are controlled so that fresh water or seawater of the cooling water flows into the bypass path 112 and does not flow into the air cooler 102.

[0108] It should be noted that since both the bypass valve 113 and the restriction valve 114 are mechanisms capable of restricting the flow rate of the air cooler 102, the control flow may be configured with only either S11 or S12.

[0109] On the other hand, as shown in Figure 6(b), when the combustion chamber temperature increasing means (1) is stopped, in S13, the bypass valve 113 of the bypass path 112 of the air cooler 102 is closed. After that, in S14, the restriction valve 114 that restricts the amount of cooling water in the air cooler 102 is opened. In other words, the bypass valve 113 and the restriction valve 114 are controlled so that fresh water or seawater cooling water does not flow into the bypass path 112, but fresh water or seawater cooling water flows into the air cooler 102.

[0110] In this way, by controlling the bypass valve 113 and the restriction valve 114, the compressed air scavenged into the combustion chamber 17 of the engine 1 is supplied to the combustion chamber 17 at a high temperature when the engine is operated in dual combustion mode in an area where the engine is navigating under high load, and as a result, the temperature of the combustion chamber 17 rises.

[0111] However, when engine 1 is operated in normal combustion mode in general sea areas where high loads are not encountered, the compressed air is cooled and supplied to combustion chamber 17, so the temperature of combustion chamber 17 does not rise.

[0112] In this way, by controlling the bypass valve 113 and the restriction valve 114 to function as the combustion chamber temperature increasing means (1), when the engine 1 is operated in dual combustion mode in an area where the ship is sailing under high load, the temperature of the combustion chamber 17 increases, but when the ship is sailing in general sea areas and the engine 1 is operated in normal combustion mode, the temperature of the combustion chamber 17 does not increase.

[0113] In this way, by changing the temperature of the combustion chamber 17, when the engine 1 is operated in the multi-combustion mode, the temperature of the combustion chamber increases, making it easier for the alternative fuel to ignite and burn, reducing the risk of unburned fuel remaining and increasing the ratio of the alternative fuel, so that the so-called multi-combustion ratio can be It can be increased.

[0114] On the other hand, when the engine 1 is operated in normal combustion mode, the combustion chamber temperature does not become high, so when fossil fuel is burned, the combustion temperature does not rise and nitrogen oxides (NOx) and other substances are not generated, thereby improving exhaust gas performance.

[0115] In this way, in this embodiment, by changing the temperature of the combustion chamber 17 when the engine 1 is operated in dual-fuel mode and when it is operated in normal combustion mode, the engine performance in each combustion mode can be improved.

[0116] As described above, in this embodiment, the engine 1 is for a ship that can navigate in sea areas at high load and at low load, and is equipped with a dual-fuel mode in which both alternative fuel and fossil fuel are injected into the combustion chamber 17 and burned, and a normal combustion mode in which only fossil fuel is injected into the combustion chamber 17 and burned, and is equipped with a combustion chamber temperature increasing means (1) that increases the temperature of the combustion chamber 17.When the ship is navigating in sea areas at high load, the dual-fuel mode is selected and the combustion chamber temperature increasing means (1) is activated to increase the temperature of the combustion chamber 17, and when the ship is navigating in sea areas at low load, the control unit 92 selects the normal combustion mode and stops the combustion chamber temperature increasing means (1) to control so as not to increase the temperature of the combustion chamber 17.

[0117] The combustion chamber temperature increasing means (1) of the first embodiment increases the temperature of the scavenging air introduced into the combustion chamber 17, and specifically, is a bypass valve 113 and a restriction valve 114 provided in the low-temperature cooling system LCL. By controlling the bypass valve 113 and the restriction valve 114 as described above, the flow path of the cooling water of the air cooler 102 is switched to the bypass path 112, the cooling performance of the air cooler 102 decreases, the temperature of the compressed air increases, and the temperature of the combustion chamber 17 increases.

[0118] As a result, when the ship is sailing in the sea area under high load, the engine 1 is operated in dual combustion mode and the combustion chamber temperature increasing means (1) is activated and controlled to increase the temperature of the combustion chamber 17, so that when the engine 1 is operated in dual combustion mode, the temperature of the combustion chamber 17 increases.

[0119] This reduces the amount of unburned alternative fuel that can occur when burning in dual-fuel mode, making it possible to increase the ratio of alternative fuel, or the so-called dual-fuel ratio.In other words, by increasing the temperature of the combustion chamber 17, the alternative fuel becomes easier to ignite and burn, making it possible to increase the dual-fuel ratio.

[0120] On the other hand, when the ship is sailing in the sea area at low load, the engine 1 is operated in the normal combustion mode, and the combustion chamber temperature increasing means (1) is not activated so as not to increase the temperature of the combustion chamber 17. Therefore, when the engine is operated in the normal combustion mode, the temperature of the combustion chamber 17 does not increase.

[0121] This reduces the generation of NOx that may occur when burning in normal combustion mode, thereby improving exhaust gas performance.

[0122] Therefore, the marine engine 1 is used in situations where the vessel is sailing in the sea area at high load and situations where the vessel is sailing in the sea area at low load, and when the vessel is sailing in the sea area at high load, the ratio of alternative fuel such as ammonia is increased to increase the so-called "mixed combustion ratio," while when the vessel is sailing in the sea area at low load, the generation of nitrogen oxides (NOx) is suppressed to improve exhaust gas performance.

[0123] In addition, in this embodiment, the bypass valve 113 and the restriction valve 114 provided in the low-temperature cooling system are configured to switch the flow path of the cooling water in the air cooler 102, thereby increasing the temperature of the scavenging air introduced into the combustion chamber 17.

[0124] As a result, the temperature of the scavenging air introduced into the combustion chamber 17 becomes higher than that in the normal combustion mode.

[0125] Therefore, since the temperature of the introduced scavenging air itself is high, the temperature of the combustion chamber 17 also inevitably rises, making it easier for the alternative fuel to ignite and burn.

[0126] Therefore, the combustibility during mixed combustion can be more reliably improved.

[0127] In this embodiment, the restriction valve 114 and the bypass valve 113 restrict the flow rate of the cooling water of the air cooler 102 that cools the scavenging air, thereby forming a combustion chamber temperature increasing means (1).

[0128] As a result, by the simple method (structure) of restricting the flow rate of the cooling water of the air cooler 102, the temperature of the scavenging air can be increased, and the temperature of the combustion chamber 17 can be increased.

[0129] Therefore, the scavenging air temperature increasing means (1) can be configured with a simple method (structure), and as a result, the temperature of the combustion chamber 17 can be increased, and the mixed combustion ratio of the alternative fuel can be increased.

[0130] In this embodiment, the restriction valve 114 and the bypass valve 113 are controlled only to be open or closed, but for example, they may be controlled to be partially open or partially closed to slightly throttle the flow of cooling water in the air cooler 102. Also, the restriction valve 114 and the bypass valve 113 may be configured to be a single two-way valve that serves both purposes.

[0131] (Embodiment 2) Next, a second embodiment will be described. The second embodiment will be described using a schematic diagram of an intake / exhaust system and a cooling system of a marine engine in Fig. 7 and a sub-control flowchart in Fig. 8. As the other components are the same as those in the first embodiment, the same reference numerals will be used and the description will be omitted.

[0132] In this second embodiment, the temperature of the combustion chamber 17 is changed by changing the cooling performance of the air cooler 102, without switching the flow path of the cooling water of the air cooler 102 as in the first embodiment.

[0133] Specifically, as shown in FIG. 7, a cooling valve 201 is provided at the seawater inlet of the seawater heat exchanger 110 provided in the low-temperature cooling system LCL, and the cooling performance of the air cooler 102 is changed by controlling the opening and closing of this cooling valve 201 by the control unit 92.

[0134] Control in this embodiment is performed according to the sub-control flowchart of Fig. 8. That is, when the combustion chamber temperature increasing means is activated, which corresponds to S4 in the main control flowchart of Fig. 5, the control flow for the operation of the combustion chamber temperature increasing means (2) is performed according to Fig. 8(a), and when the combustion chamber temperature increasing means is stopped, which corresponds to S6 in the main control flowchart of Fig. 5, the control flow for the stop of the combustion chamber temperature increasing means (2) is performed according to Fig. 8(b). Note that the "combustion chamber temperature increasing means (2)" is also referred to as the combustion chamber temperature increasing means of the second embodiment.

[0135] When the combustion chamber temperature increasing means (2) is activated, the cooling valve 201 of the seawater heat exchanger 110 is closed in S21. On the other hand, when the combustion chamber temperature increasing means (2) is deactivated, the cooling valve 201 of the seawater heat exchanger 110 is opened in S22.

[0136] By controlling the cooling valve 201 in this way, first, when the cooling valve 201 is closed, the cooling performance of the seawater heat exchanger 110 decreases, and the cooling water flowing through the low-temperature cooling system LCL cannot be cooled. As a result, the temperature of the cooling water flowing through the air cooler 102 increases, the cooling performance of the air cooler 102 decreases, and the temperature of the air scavenged into the combustion chamber 17 increases. As a result, the temperature of the combustion chamber 17 increases.

[0137] On the other hand, when the cooling valve 201 is opened, the cooling performance of the seawater heat exchanger 110 improves, the cooling water flowing through the low-temperature cooling system LCL is cooled, and the temperature of the cooling water flowing through the air cooler 102 decreases. Therefore, the cooling performance of the air cooler 102 improves, and the temperature of the air scavenged into the combustion chamber 17 decreases. As a result, the temperature of the combustion chamber 17 decreases.

[0138] In this way, by controlling the opening and closing of the cooling valve 201, the temperature of the combustion chamber 17 can be changed.

[0139] As described above, in this embodiment, the combustion chamber temperature increasing means (2) increases the temperature of the scavenging air, and specifically, is the cooling valve 201 that can adjust the temperature of the cooling water of the air cooler 102 that cools the scavenging air.

[0140] This allows the cooling performance of the air cooler 102 to be reduced and the temperature of the scavenging air to be increased without changing the flow rate of the cooling water flowing through the air cooler 102.

[0141] Therefore, the temperature of the scavenging air can be increased without reducing the flow rate of the cooling water flowing through the air cooler 102, and as a result, the temperature of the combustion chamber 17 can be increased.

[0142] Therefore, the flow rate of the cooling water in the air cooler 102 can be kept constant at all times, reducing the risk of failure of the air cooler 102. In addition, by increasing the temperature of the combustion chamber 17, the mixed combustion rate of alternative fuels can be increased.

[0143] In this embodiment, only the control of opening or closing the cooling valve 201 has been described, but it is also possible to open only a portion of the cooling valve 201 to slightly reduce the amount of seawater and maintain the cooling performance of the seawater heat exchanger 110.

[0144] (Embodiment 3) Next, a third embodiment will be described. The third embodiment will be described using a schematic diagram of an intake / exhaust system and a cooling system of a marine engine in Fig. 9 and a sub-control flowchart in Fig. 10. The third embodiment is similar to the second embodiment, and other configurations are similar to the first embodiment, so the same reference numerals will be used and the description will be omitted.

[0145] In this third embodiment, the temperature of the combustion chamber 17 is changed by improving the high-temperature cooling system HCL.

[0146] Specifically, as shown in FIG. 9, a water channel valve 301 for cylinder cooling water is provided in the path of the high-temperature cooling system HCL, and the temperature of the combustion chamber 17 is changed by controlling the opening and closing of this water channel valve 301 by the control unit 92.

[0147] The control of this embodiment is performed according to the sub-control flowchart of Fig. 10. That is, the operation of the combustion chamber temperature increasing means corresponding to S4 in the main control flowchart of Fig. 5 is performed according to the control flow of the operation of the combustion chamber temperature increasing means (3) in Fig. 10(a), and the stop of the combustion chamber temperature increasing means corresponding to S6 in the main control flowchart of Fig. 5 is performed according to the control flow of the combustion chamber temperature increasing means (3) in Fig. 10(b). The stop control flow is carried out. Note that the "combustion chamber temperature increasing means (3)" is also referred to as the combustion chamber temperature increasing means of the third embodiment.

[0148] When the combustion chamber temperature increasing means (3) is activated, the cylinder cooling water passage valve 301 is closed in S31. On the other hand, when the combustion chamber temperature increasing means (3) is deactivated, the cylinder cooling water passage valve 301 is opened in S32.

[0149] In this way, by controlling the water passage valve 301 for the cylinder cooling water, first, when the water passage valve 301 is closed, cooling water does not flow into the engine cylinder 13, so the engine cylinder 13 is heated, and the combustion chamber 17 provided in the engine cylinder 13 itself is also heated. As a result, the temperature of the combustion chamber 17 increases.

[0150] On the other hand, when the water passage valve 301 is opened, the cooling water flows into the engine cylinder 13, so that the engine cylinder 13 is cooled, and the combustion chamber 17 of the engine cylinder 13 is also cooled. As a result, the temperature of the combustion chamber 17 decreases.

[0151] In this way, by controlling the opening and closing of the water passage valve 301, the temperature of the combustion chamber 17 can be changed in this embodiment as well.

[0152] As described above, in this embodiment, the combustion chamber temperature increasing means (3) increases the temperature of the combustion chamber 17 itself, and specifically, is the water channel valve 301 that limits the flow rate of the cooling water that cools the engine cylinder 13.

[0153] As a result, the flow rate of the cooling water that cools the engine cylinder 13 decreases, and the temperature of the engine cylinder 13 increases, which in turn increases the temperature of the combustion chamber 17 provided within the engine cylinder 13.

[0154] Therefore, the temperature of the combustion chamber 17 can be increased, and the ratio of the alternative fuel in the mixed combustion can be increased.

[0155] Therefore, by simply restricting the flow rate of the cooling water in the engine cylinder 13, the temperature in the combustion chamber 17 can be increased, and the ratio of the alternative fuel in the mixed combustion can be increased.

[0156] In this embodiment, only the control of opening or closing the waterway valve 301 has been described, but it is also possible to control it so that it is partially open when closed, reducing the flow rate of the cooling water to a small amount, thereby maintaining the cooling performance of the engine cylinder 13 as much as possible.

[0157] (Embodiment 4) Next, a fourth embodiment will be described. The fourth embodiment will be described using a schematic diagram of an intake / exhaust system and a cooling system of a marine engine in Fig. 11 and a sub-control flowchart in Fig. 12. Since the fourth embodiment is similar to the other embodiments and other configurations are similar to the first embodiment, the same reference numerals will be used and the description will be omitted.

[0158] In this fourth embodiment, the intake and exhaust system of the engine 1 is improved to change the temperature of the combustion chamber 17.

[0159] Specifically, as shown in FIG. 11, an air exhaust valve 401 that discharges part of the air in the intake system to the outside is provided in the path of the intake and exhaust system AL, and a bypass valve 402 that bypasses the exhaust gas from the turbocharger 101 is provided.

[0160] The control of this embodiment is performed according to the sub-control flowchart of Fig. 12. That is, the operation of the combustion chamber temperature increasing means corresponding to S4 in the main control flowchart of Fig. 5 is performed according to the control flow for the operation of the combustion chamber temperature increasing means (4) in Fig. 12(a), and the stop of the combustion chamber temperature increasing means corresponding to S6 in the main control flowchart of Fig. 5 is performed according to the control flow for the stop of the combustion chamber temperature increasing means (4) in Fig. 12(b). Note that the "combustion chamber temperature increasing means (4)" is also referred to as the combustion chamber temperature increasing means of the fourth embodiment.

[0161] In the operation of the combustion chamber temperature increasing means (4), the air discharge valve 401 that discharges part of the compressed air is opened in S41. Next, the bypass valve 402 that bypasses the exhaust gas from the turbocharger 101 is opened in S42.

[0162] By opening the air exhaust valve 401 in this way, the amount of compressed air supplied to the combustion chamber 17 is reduced. On the other hand, by opening the bypass valve 402, the rotation speed of the turbocharger 101 is reduced, and the amount of compressed air supplied to the combustion chamber 17 is reduced. In either case, the amount of compressed air supplied to the combustion chamber 17 is reduced, and the temperature of the combustion chamber 17 can be increased.

[0163] On the other hand, when the combustion chamber temperature increasing means (4) is stopped, the air discharge valve 401 that discharges part of the compressed air is closed in S43. Next, the bypass valve 402 that bypasses the exhaust gas from the turbocharger 101 is closed in S44.

[0164] In this way, by closing the air exhaust valve 401 and the bypass valve 402, there is no decrease in the amount of compressed air supplied to the combustion chamber 17. Therefore, the temperature of the combustion chamber does not increase.

[0165] Therefore, in this embodiment, as in the other embodiments, in the mixed combustion mode, the temperature of the combustion chamber 17 can be increased, thereby increasing the mixed combustion ratio, and in the normal combustion mode, the temperature of the combustion chamber 17 is low, thereby suppressing the generation of nitrogen oxides (NOx) and the like, thereby improving exhaust gas performance.

[0166] In this embodiment, the air exhaust valve 401 and the bypass valve 402 are provided and controlled, but only one of them may be provided and controlled. Also, although only the control of opening or closing has been described, it is also possible to partially open the valve.

[0167] (Embodiment 5) Next, a fifth embodiment will be described. The fifth embodiment will be described using the schematic diagram showing the configuration of a marine engine in Fig. 13, the system schematic diagram showing an exhaust valve device in Fig. 14, the operation flowchart of the exhaust valve device in Fig. 15, and the sub-control flowchart in Fig. 16. Since the fifth embodiment is similar to the other embodiments and other components are similar to those of the first embodiment, the same reference numerals will be used and the description thereof will be omitted.

[0168] In this fifth embodiment, the temperature of the combustion chamber 17 is changed by improving the opening and closing timing of the exhaust valve 18.

[0169] First, the exhaust valve device EX of the engine 1 will be described with reference to FIGS.

[0170] As shown in FIG. 13, the exhaust valve device EX of this embodiment comprises an exhaust valve 18 located above the combustion chamber 17 and reciprocating up and down, an upper valve train 501 that is provided above the exhaust valve 18 and causes the exhaust valve 18 to reciprocate up and down, a lower valve train 502 that is provided near the fuel pump 41 and connected to the upper valve train 501 via an oil passage to provide a driving force to the upper valve train 501, and a lower valve train 502 that is connected to the upper valve train 501 and supplies air to the upper valve train 502. and an air supply unit 503 that supplies air.

[0171] 14, lower valve gear 502 is provided with control valve 504 that controls the hydraulic pressure, and is connected to pressure accumulator 505 that applies operating pressure to control valve 504. Control valve 504 is electrically connected to exhaust valve control section 506, which is electrically connected to detection section 507 that detects the engine crank angle, etc.

[0172] The exhaust valve device EX configured in this manner operates in accordance with the operation flowchart of the exhaust valve device shown in FIG.

[0173] First, in S101, the engine crank angle is detected by the detection unit 507. Next, in S102, a valve open command is transmitted from the exhaust valve control unit 506 at a predetermined timing.

[0174] Then, in S103, the control valve 504 opens and the hydraulic pressure is transmitted from the pressure accumulator 505 to the lower valve train 502. Then, in S104, a piston (not shown) of the lower valve train 502 operates and the hydraulic pressure is transmitted to the upper valve train 501. Then, in S105, the upper valve train 501 is pushed by the hydraulic pressure and presses the exhaust valve 108 downward, thereby opening the exhaust valve 108.

[0175] Thereafter, in S106, a valve close command is sent at a predetermined timing from the exhaust valve control unit 506. Then, in S107, the control valve 504 closes, the hydraulic pressure from the pressure accumulator 505 disappears, and the piston (not shown) of the lower valve gear 502 returns.

[0176] As a result, in S108, the hydraulic pressure from the lower valve train 502 disappears, eliminating the downward pressing force on the upper valve train 501. Then, in S109, the downward pressing force on the upper valve train 501 disappears, and the exhaust valve 18 moves upward with the air from the air supply unit 503, causing the exhaust valve 18 to close.

[0177] In this manner, the exhaust valve device EX of this embodiment operates.

[0178] In this embodiment, based on this exhaust valve device EX, the opening and closing timing of the exhaust valve 18 is improved. Specifically, this is performed according to the sub-control flowchart of FIG.

[0179] That is, the operation of the combustion chamber temperature increasing means corresponding to S4 in the main control flowchart of Fig. 5 is performed by the control flow for the operation of the combustion chamber temperature increasing means (5) in Fig. 16(a), and the stop of the combustion chamber temperature increasing means corresponding to S6 in the main control flowchart of Fig. 5 is performed by the control flow for the stop of the combustion chamber temperature increasing means (5) in Fig. 16(b). Note that the "combustion chamber temperature increasing means (5)" is also referred to as the combustion chamber temperature increasing means of the fifth embodiment.

[0180] When the combustion chamber temperature increasing means (5) is activated, a valve close command is sent from the exhaust valve control unit 506 at an early timing in S51, and the exhaust valve 18 closes at the early timing. On the other hand, when the combustion chamber temperature increasing means (4) is deactivated, a valve close command is sent from the exhaust valve control unit 506 at a standard timing in S52, and the exhaust valve 18 closes at the standard timing.

[0181] Here, the term "advanced timing" refers to timing that is earlier than the standard timing, for example, timing that is advanced by 0 to 60 degrees. The reason there is such a range of advance angles is that the timing changes depending on the operating state of the engine.

[0182] By controlling in this way, when engine 1 is operating in dual combustion mode, exhaust valve 1 This causes exhaust valve 18 to close early, increasing the temperature of combustion chamber 17. In other words, by closing exhaust valve 18 early, the period during which the air supplied to combustion chamber 17 is compressed by piston 21 becomes longer in the next cycle, and as a result, the temperature of combustion chamber 17 also increases.

[0183] On the other hand, when the engine 1 is operated in the normal combustion mode, the exhaust valve 18 is closed as usual, so the temperature of the combustion chamber 17 does not increase.

[0184] As described above, this embodiment is an exhaust valve device EX in which the combustion chamber temperature increasing means (5) advances the closing timing of the exhaust valve 18.

[0185] This advances the closing timing of the exhaust valve 18, making it possible to lengthen the period during which air is compressed by the piston 21 in the next cycle.

[0186] Therefore, the period during which the air in the combustion chamber 17 is compressed becomes longer, and as a result, the temperature of the combustion chamber 17 increases.

[0187] Therefore, by advancing the closing timing of the exhaust valve 18, the temperature of the combustion chamber 17 can be increased, thereby providing a combustion chamber temperature increasing means without affecting the cooling system of the engine 1, and also increasing the mixed combustion ratio of the alternative fuel.

[0188] (Embodiment 6) Next, a sixth embodiment will be described. The sixth embodiment will be described using a schematic diagram showing the configuration of a marine engine in Fig. 17 and a sub-control flowchart in Fig. 18. The sixth embodiment is similar to the other embodiments, and other configurations are similar to those of the first embodiment, so the same reference numerals will be used and the description will be omitted.

[0189] In this sixth embodiment, a so-called "hot bulb" is used to change the temperature of the combustion chamber 17. The "hot bulb" is a spherical shell-shaped ball made of cast iron that becomes a heat source when heated by engine combustion or external thermal power.

[0190] 17, in this embodiment, a hot bulb chamber 602 containing a hot bulb 601 is provided above the combustion chamber 17 of the engine 1. The hot bulb chamber 602 and the combustion chamber 17 are connected via a communication passage 603, and a hot bulb valve (not shown) that opens and closes the communication is provided in the communication passage 603. The hot bulb valve is electrically connected to a hot bulb valve control unit 604 that controls the opening and closing of the hot bulb valve.

[0191] The control of this embodiment is performed according to the sub-control flowchart of Fig. 18. That is, the operation of the combustion chamber temperature increasing means corresponding to S4 in the main control flowchart of Fig. 5 is performed according to the control flow for the operation of the combustion chamber temperature increasing means (6) in Fig. 18(a), and the stop of the combustion chamber temperature increasing means corresponding to S6 in the main control flowchart of Fig. 5 is performed according to the control flow for the stop of the combustion chamber temperature increasing means (6) in Fig. 18(b). Note that the "combustion chamber temperature increasing means (6)" is also referred to as the combustion chamber temperature increasing means of the sixth embodiment.

[0192] In the operation of the combustion chamber temperature increasing means (6), in S61, a valve open command is sent from the hot bulb valve control unit 604 to open the hot bulb valve (not shown). When the hot bulb valve (not shown) opens in this way, the hot bulb 601 present in the hot bulb chamber 602 functions as a heat source, and as a result, the temperature of the combustion chamber 17 rises.

[0193] On the other hand, when the combustion chamber temperature increasing means (6) is stopped, the hot bulb valve control unit 604 issues a valve closing command in S62. When the hot bulb valve is closed, the effect of the hot bulb 602 in the hot bulb chamber 602 does not reach the combustion chamber 17, so the temperature of the combustion chamber 17 does not change.

[0194] As described above, in this embodiment, the combustion chamber temperature increasing means (6) is a hot bulb valve control unit 604 that controls a hot bulb valve (not shown) provided in a communication passage 603 that connects the hot bulb chamber 602 in which the hot bulb 601, which is a heat source, is placed and the combustion chamber 17.

[0195] As a result, when the hot bulb valve control unit 604 opens the hot bulb valve, the hot air in the hot bulb chamber 602 heated by the hot bulb 601, which is the heat source, is transferred to the combustion chamber 17, heating the combustion chamber 17.

[0196] This ensures that the temperature in the combustion chamber 17 increases, and the ratio of alternative fuels in the mixed combustion can be increased.

[0197] Therefore, the temperature of the combustion chamber 17 can be reliably increased by using the hot bulb 601 as a heat source, and the mixed combustion ratio, which is the ratio of the alternative fuel, can be increased.

[0198] (Other embodiments) Various embodiments have been described above, but the present invention is not limited to these. Any embodiment in which the temperature of the combustion chamber in the dual-fuel combustion mode is higher than the temperature of the combustion chamber in the normal combustion mode is within the technical scope of the present invention.

[0199] Furthermore, the alternative fuel is not limited to ammonia, but may be any fuel that can be substituted for petroleum, such as biofuel, methanol, or ethanol. [Industrial Applicability]

[0200] As described above, the present invention relates to a marine engine used in a ship, and is particularly useful in a marine engine that can burn alternative fuels such as ammonia together with conventional fossil fuels. [Explanation of symbols]

[0201] 1. Marine engine 10...Cylinder 17...Combustion chamber 30...Fuel injection valve 92...Control unit 112...Bypass valve (combustion chamber temperature increasing means (1)) 113...Restriction valve (combustion chamber temperature increasing means (1)) 201...Cooling valve (combustion chamber temperature increasing means (2)) 301... Water passage valve (combustion chamber temperature increasing means (3)) 401...Air exhaust valve (combustion chamber temperature increasing means (4)) 402...Bypass valve (combustion chamber temperature increasing means (4)) EX... Exhaust valve device (combustion chamber temperature increasing means (5)) 604...Hot bulb valve control unit (combustion chamber temperature increasing means (6))

Claims

1. A marine engine used in a situation where a ship navigates in an ocean area under high load and a situation where a ship navigates in an ocean area under low load, a combustion mode selection means for selecting a mixed combustion mode in which both the alternative fuel and the fossil fuel are injected into the combustion chamber and burned, and a normal combustion mode in which the fossil fuel is injected into the combustion chamber and burned; a combustion chamber temperature increasing means for increasing the temperature of the combustion chamber, In a scene where the ship is sailing in a sea area under high load, the combustion mode selection means selects the dual combustion mode, and the combustion chamber temperature increasing means is operated to increase the temperature of the combustion chamber, When the ship is sailing in a sea area at a low load, the combustion mode selection means selects the normal combustion mode, and the combustion chamber temperature increasing means is stopped to control the temperature of the combustion chamber not to increase. A marine engine characterized by:

2. The combustion chamber temperature increasing means is a scavenging air temperature increasing means for increasing the temperature of the scavenging air introduced into the combustion chamber.

2. A marine engine according to claim 1.

3. The scavenging air temperature increasing means is an air cooler cooling water flow rate limiting mechanism that limits the flow rate of cooling water in an air cooler that cools the scavenging air.

3. A marine engine according to claim 2.

4. The scavenging air temperature increasing means is an air cooler cooling water temperature increasing mechanism that increases the temperature of the cooling water of an air cooler that cools the scavenging air.

3. A marine engine according to claim 2.

5. The combustion chamber temperature increasing means is an engine cylinder cooling water flow rate limiting mechanism that limits the flow rate of cooling water that cools the engine cylinder.

2. A marine engine according to claim 1.

6. The combustion chamber temperature increasing means is an exhaust valve advance mechanism that advances the closing timing of the exhaust valve.

2. A marine engine according to claim 1.

7. The combustion chamber temperature increasing means is a bulb communication mechanism that communicates the combustion chamber with a bulb chamber in which a bulb serving as a heat source is disposed.

2. A marine engine according to claim 1.

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