gas engine

Abstract

To provide a gas engine with excellent combustibility for burning gas, which has, in a cylinder, a plurality of fuel injection valves for injecting gas of fuel, does not need to increase the rigidity of the engine itself by preventing a large heat load from being applied to the cylinder or the like while improving combustibility, and can suppress a NOx emission.SOLUTION: As shown in (a), only a hydrogen reservoir α injected from a fuel injection valve A30 is ignited P by an ignition plug A32. Then, as shown in (b), a flame α generated by the combustion of the hydrogen reservoir α makes a half turn inside a cylinder 10, catches up with a hydrogen reservoir β injected from a fuel injection valve B31, ignites P the hydrogen reservoir β, and then burns the hydrogen reservoir β.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a gas engine that burns highly combustible gas such as hydrogen. [Background technology]

[0002] In recent years, issues such as global warming have led to calls for the realization of zero carbon dioxide emissions, or so-called zero-emissions. Because it is difficult to achieve zero emissions with existing engines that use fossil fuels such as heavy oil, there has been much development of gas engines that use combustible gases that do not have carbon in their molecular structure, such as hydrogen.

[0003] For example, Patent Document 1 below proposes a hydrogen engine that uses hydrogen as fuel. This patent document describes a hydrogen engine in which, in order to suppress the temperature rise near the spark plug and reduce the NOx concentration in the combustion gas, two spark plugs and two fuel injection valves are provided opposite each other inside the cylinder, and these two spark plugs are ignited simultaneously, thereby shortening the propagation distance of the combustion flame and suppressing the temperature rise near the spark plug.

[0004] It is true that when burning highly combustible gases such as hydrogen, the fuel burns more rapidly than in conventional engines that use fossil fuels, causing the temperature around the plug to rise more rapidly, resulting in an increase in the amount of NOx in the combustion gas (exhaust gas).Therefore, it is necessary to devise a way to reduce the combustion temperature by providing two spark plugs, as in Patent Document 1, thereby reducing the total amount of fuel around each spark plug. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 58-12457 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, as in Patent Document 1, when two fuel injection valves and two spark plugs are provided in a cylinder and the two spark plugs are fired simultaneously, the propagation distance of the combustion flame is certainly shortened.

[0007] However, when two combustions occur simultaneously in one cylinder, the pressure inside the cylinder increases rapidly, which can place a large thermal load on the cylinder. If a large thermal load is placed on the cylinder in this way, it becomes necessary to increase the pressure resistance of the cylinder and piston inner surface, as well as the mounting strength of the spark plug, which in turn requires an increase in the rigidity of the engine itself, resulting in problems such as an increase in engine manufacturing costs and the problem that the rapid combustion still results in high emissions of NOx, a harmful substance.

[0008] The present invention has been made in consideration of the above points, and its purpose is to provide a gas engine that burns a gas with high combustibility, and that has multiple fuel injection valves inside the cylinder that inject fuel gas, thereby improving combustibility while not placing a large thermal load on the cylinder, etc., thereby eliminating the need to increase the rigidity of the engine itself and also reducing NOx emissions. [Means for solving the problem]

[0009] To achieve this objective, this invention is characterized in that a gas engine that burns highly combustible gases such as hydrogen is provided with a plurality of fuel injection valves that inject fuel gas into the cylinder, and is equipped with ignition means that burns one of the plurality of gas reservoirs injected from the plurality of fuel injection valves before the other gas reservoirs.

[0010] Specifically, in the first invention, a highly combustible gas such as hydrogen is burned. Crosshead type A gas engine is provided with a cylindrical cylinder whose interior serves as a combustion chamber, and the cylinder is provided with Circumferential direction A plurality of fuel injection valves are provided to inject gas at spaced positions, a swirl flow generating means for generating a swirl flow in the air drawn into the cylinder, the plurality of fuel injection valves being configured to simultaneously inject gas near the top dead center of the piston, and the plurality of gas pools injected by the fuel injection valves being configured to swirl due to the swirl flow of the air;At least one of the gas reservoirs Burning with an ignition means, Other gas reservoirs The flames of the gas pool that swirls around the circumference and burns first are then used to burn the fuel. It is characterized by the following.

[0011] According to this configuration, the cylinder is provided with a plurality of fuel injection valves that inject gas at positions spaced apart from one another, and an ignition means is provided that burns one of the plurality of gas reservoirs injected from the plurality of fuel injection valves before the other gas reservoirs, so that the plurality of gas reservoirs are combusted one by one in sequence. In other words, rather than the plurality of gas reservoirs combusting simultaneously, one gas reservoir combusts first, and then the other gas reservoirs are combusted under the influence of the flame of the gas reservoir that combusted first.

[0012] As a result, the multiple gas pools combust one by one in sequence, which slows the combustion and causes a gradual increase in pressure inside the cylinder due to combustion.

[0013] The ignition means may be a general spark plug, or may be a glow plug, a hot bulb, or other ignition means that promotes the combustion of gas.

[0014] Furthermore, the number of ignition means is not limited to one, and multiple ignition means may be provided depending on the number of fuel injection valves, etc. In this case, when multiple ignition means are provided, only one ignition means needs to be activated in one combustion cycle. In this case, the ignition means to be activated may be switched at regular intervals.

[0015] No. 2 In the invention, the fuel injection valve is composed of a first fuel injection valve that injects the gas reservoir to be burned first, and a second fuel injection valve that injects the gas reservoir to be burned later, and is characterized by having a control means that makes the amount of gas reservoir injected from the first fuel injection valve less than the amount of gas reservoir injected from the second fuel injection valve.

[0016] With this configuration, the amount of gas in the gas reservoir that is burned first is small, and the amount of gas in the gas reservoir that is burned later is large. Therefore, the heat release rate caused by combustion, i.e., the amount of heat generated per unit time by combustion in the engine (ROHR·rate of heat release) se) waveform is small in the first half of combustion and large in the second half of combustion.

[0017] Therefore, in the early stages of combustion when the piston is near top dead center and the combustion chamber is small, the amount of heat is reduced to limit thermal energy loss and the combustion temperature is also kept down, thereby reducing the generation of NOx.However, in the later stages of combustion when the piston is away from top dead center and the combustion chamber is large, the amount of heat is increased to maximize the effect of thermal energy, and the combustion temperature does not rise as much, making it less likely that NOx will be generated.

[0018] Therefore, a more ideal combustion state of the engine can be obtained. [Effects of the Invention]

[0019] As described above, according to the present invention, a plurality of gas pools are combusted one by one in sequence, and the pressure rise due to combustion inside the cylinder occurs gradually.

[0020] Therefore, in a gas engine that burns highly combustible gas, by providing multiple fuel injection valves injecting fuel gas into the cylinder, it is possible to improve combustibility while avoiding a large thermal load on the cylinder, thereby eliminating the need to increase the rigidity of the engine itself. Also, NOx emissions can be reduced. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing the configuration of a gas engine according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a diagram explaining the uniflow scavenging method of a gas engine; (a) is a detailed cross-sectional view of the lower part of the cylinder, and (b) is a cross-sectional view of the lower part of the cylinder. [Figure 3]FIG. 2 is a detailed cross-sectional view of the cylinder head of the first embodiment. [Figure 4] FIG. 2 is a view showing a ceiling surface of the cylinder head of the first embodiment. [Figure 5] 1 is a system block diagram of a control system for a gas engine according to a first embodiment. [Figure 6] 1A and 1B are diagrams showing the combustion state of the gas engine of the first embodiment, in which (a) is a diagram showing the early stage of combustion, and (b) is a diagram showing the later stage of combustion. [Figure 7] 3 is a graph showing changes in the rate of heat release (ROHR) caused by combustion in the first embodiment. FIG. [Figure 8] 10A and 10B are diagrams showing the combustion state of the gas engine of the second embodiment, in which (a) is a diagram showing the early stage of combustion, and (b) is a diagram showing the later stage of combustion. [Figure 9] FIG. 10 is a graph showing changes in the rate of heat release (ROHR) caused by combustion in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] 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.

[0023] (Embodiment 1) 1 is a schematic diagram illustrating the configuration of a marine gas engine 1, and this diagram will be used to explain the outline of the gas engine 1. Hereinafter, the marine gas engine 1 will be simply referred to as "engine 1."

[0024] The engine 1 is an in-line multi-cylinder gas engine equipped with multiple cylinders 10. 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. The uniflow scavenging system will be described later with reference to Figure 2.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] Additionally, the cylinder cover 15 is provided with an exhaust valve 18 that is operated by a valve train (not shown). 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.

[0033] The cylinder cover 15 also defines a ceiling surface 16 of the combustion chamber 17. As will be described later, a plurality of fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 are provided on this ceiling surface 16. In this embodiment, each cylinder 10 is provided with two fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31.

[0034] FIG. 2 is a diagram illustrating a uniflow scavenging method that generates a swirling air flow inside the cylinder 10, where (a) is a detailed cross-sectional view of the lower part of the cylinder, and (b) is a cross-sectional view of the lower part of the cylinder.

[0035] 2, a plurality of scavenging holes 40 that take in air from the outside are provided in the cylinder liner 14 at the bottom of the cylinder 10. As shown in (b), these scavenging holes 40 are opened at a slight angle in the tangential direction of the cylinder liner 40.

[0036] Therefore, as shown in FIG. 2, when air is taken into the cylinder 10 through the scavenging holes 40, a swirling flow of air is generated within the cylinder 10.

[0037] In this way, the swirling air flow generated within the cylinder 10 exerts an effective function in the combustion of gas, as will be described later.

[0038] Next, a detailed structure of the vicinity of the cylinder cover 15 of the engine of this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a detailed cross-sectional view of the cylinder head of the first embodiment, and Figure 4 is a view showing the ceiling surface of the cylinder head of the first embodiment.

[0039] As described above, the cylinder cover 15 has the exhaust valve 18 disposed in the center of the ceiling surface 16, and multiple fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 are provided on this ceiling surface 16. Specifically, two fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 are provided at approximately diagonal positions on the inclined surface of the ceiling surface 16. Hydrogen, which is a combustible gas, is injected from these fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31. Note that the hydrogen supply paths to these fuel injection valves 30, 31 and the like are well-known structures and will not be described in detail here.

[0040] Furthermore, spark plugs (spark plug A, spark plug B) 32, 33 serving as ignition means are provided on the ceiling surface 16 of the cylinder cover 15 at positions slightly offset in the circumferential direction from the fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31. Similar to the fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 described above, a plurality of these spark plugs 32, 33 (spark plug A, spark plug B) are provided.

[0041] In this embodiment, the circumferential offset of the spark plugs (spark plug A, spark plug B) 32, 33 from the fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 is set to approximately 10° to 45°. However, it is desirable to appropriately set this circumferential offset depending on the performance of the fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31, the amount of hydrogen injected, the injection speed, and the swirling speed of the swirling air flow, etc.

[0042] These spark plugs (spark plug A, spark plug B) 32, 33 ignite and burn the hydrogen (hydrogen pool) injected by the fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 by providing a spark. By burning hydrogen in this way with the spark plugs (spark plug A, spark plug B) 32, 33, it is possible to produce gas engine combustion suitable for the engine 1.

[0043] Next, an outline of the system blocks of the control system for the engine 1 of this embodiment will be described.

[0044] 5, the engine control system of this embodiment has, as input means, a start switch 51 for starting the engine 1, a steering wheel 52 for controlling the rotation speed of the engine 1, a selection switch 53 for switching between combustion state modes, and an environmental sensor 54 for detecting the external environment and inputting information about the external environment. Calculation processing is performed in the engine control unit 50 based on information from these input means. A storage means 55 is connected to the engine control unit 50, and various data used in the calculation processing, predetermined map information, etc. are retrieved from the storage means 55.

[0045] The engine control unit 50 is configured to transmit the output signals calculated therein to the fuel injector A30, the fuel injector B31, the spark plug A32, and the spark plug B33, which are output means.

[0046] With this configuration, the control system for the engine 1 of this embodiment controls the operating state of the engine 1 appropriately.

[0047] Next, the operating state of the engine of this embodiment will be explained using Figures 6 and 7. Figure 6 shows the combustion state, with (a) showing the early stage of combustion and (b) showing the later stage of combustion. Figure 7 shows the change in the rate of heat release (ROHR) caused by combustion in this embodiment.

[0048] 6(a), at the beginning of combustion, the same amount of hydrogen fuel is injected from each of two fuel injectors, specifically, fuel injector A 30 and fuel injector B 31. This injected hydrogen forms hydrogen reservoirs α and β within cylinder 10.

[0049] Of these, only the hydrogen reservoir α injected from the fuel injection valve A30 is ignited P by the spark plug A32. In this way, when only one hydrogen reservoir α is ignited P and combusted, the pressure increase due to combustion can be suppressed more than when two hydrogen reservoirs α and β are ignited and combusted simultaneously.

[0050] Then, as shown in (b), the flame α generated by the combustion of the hydrogen pool α travels halfway around the cylinder 10 and catches up with the hydrogen pool β injected from the fuel injection valve B31, igniting the hydrogen pool β at P, which then also burns the hydrogen pool β. In other words, the hydrogen pool β is not ignited by the spark plug B33 (see FIG. 6(a)), but is ignited P by the flame α of the hydrogen pool that burned earlier, and then burns.

[0051] Due to this combustion state, the engine 1 of this embodiment exhibits a change in the rate of heat release (ROHR) as shown in Figure 7. In this figure, the vertical axis represents the value of the rate of heat release (ROHR), and the horizontal axis represents the value of the elapsed time when the piston 21 moves from near the top dead center toward the bottom dead center.

[0052] In this figure, the values ​​shown by the solid line are the values ​​when two hydrogen pools α and β are ignited and burned simultaneously by two spark plugs (spark plug A and spark plug B) 32 and 33, and the values ​​shown by the dashed line are the values ​​when burned in this embodiment.

[0053] As can be seen from this figure, when two hydrogen pools α and β are ignited simultaneously by two spark plugs (spark plug A and spark plug B) 32 and 33 (solid line), the rate of heat release (ROHR) rises sharply and then decreases rapidly. This rapid increase in the rate of heat release (ROHR) can potentially impose a large thermal load on the interior of the cylinder 10. This requires increasing the pressure resistance of the cylinder 10, piston 21, and other internal components, as well as the mounting strength of the spark plugs 32 and 33. This in turn requires increasing the rigidity of the engine 1 itself, resulting in increased engine manufacturing costs. Furthermore, because the fuel burns completely within a relatively small area, the temperature rises in a localized space, resulting in continued high NOx emissions.

[0054] In contrast, in the case of this embodiment (indicated by the dashed line), the value of the rate of heat release (ROHR) gradually increases, then decreases, then increases again, and then gradually decreases again. In this way, the value of the rate of heat release (ROHR) gradually increases and is maintained over a long period of time, so that in this embodiment, a large thermal load is not applied to the interior of the cylinder 10. Therefore, there is no need to increase the pressure resistance of the inner surfaces of the cylinder 10, piston 21, etc., or the mounting strength of the spark plugs 32, 33, and there is no need to increase the rigidity of the engine 1 itself. Furthermore, because the fuel diffusion area and combustion area are expanded, the amount of temperature rise is reduced compared to when two spark plugs are used simultaneously to ignite the engine. This reduces the amount of NOx generation.

[0055] Therefore, the cost of manufacturing the engine can be reduced. That is, according to this embodiment, even when burning a highly combustible gas such as hydrogen, there is no need to increase the rigidity of the engine 1 itself.

[0056] As described above, in this embodiment, the engine 1 burns hydrogen, which has good combustibility, and is characterized in that the engine 1 is provided with a cylindrical cylinder 10 whose interior forms a combustion chamber 17, and the cylinder 10 is provided with a plurality of fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 that inject hydrogen at positions spaced apart from each other, and is equipped with an ignition plug (ignition plug A) 32 that burns one hydrogen reservoir α of the multiple hydrogen reservoirs α, β injected from the multiple fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 before the other hydrogen reservoir β.

[0057] This causes the multiple hydrogen pools α and β to combust one by one in sequence.In other words, instead of multiple hydrogen pools α and β combusting simultaneously, one hydrogen pool α combusts first, and then the other hydrogen pool β combusts under the influence of the flame from the hydrogen pool α that combusted first.

[0058] Therefore, the multiple hydrogen pools α and β are combusted one by one in sequence, the combustion is slowed down, and the pressure inside the cylinder 10 rises slowly.

[0059] Therefore, in engine 1 that burns hydrogen, which has good combustibility, by providing multiple fuel injection valves (fuel injection valve A, fuel injection valve B) 30, 31 that inject hydrogen fuel into cylinder 10, it is possible to improve combustibility while preventing a large thermal load from being applied to cylinder 10, etc., thereby eliminating the need to increase the rigidity of engine 1 itself. In addition, NOx emissions can be suppressed.

[0060] In addition, in this embodiment, scavenging holes 40... that generate a swirling flow in the air drawn into the cylinder 10 are provided in the lower part of the cylinder 10, and the hydrogen reservoirs α and β injected by the fuel injection valves (fuel injection valve A, fuel injection valve B) 30 and 31 are configured to swirl due to the swirling flow of the air.

[0061] As a result, the hydrogen pools α and β injected by the fuel injection valves (fuel injection valve A, fuel injection valve B) 30 and 31 are caused to swirl within the cylinder 10 by the swirling air flow.

[0062] Therefore, when one hydrogen reservoir α burns first and another hydrogen reservoir β burns under the influence of the hydrogen reservoir α that burned first, the swirling air flow makes it more susceptible to the influence of the flame, thereby shortening the combustion interval.

[0063] Therefore, even if the combustion period is longer than when multiple hydrogen reservoirs are ignited simultaneously, the interval between each combustion when multiple hydrogen reservoirs α and β are combusted in sequence is shortened, and pressure fluctuations accompanying pressure increases occur smoothly, preventing adverse effects on the rotation of engine 1.

[0064] (Embodiment 2) Next, a second embodiment will be described with reference to Figures 8 and 9. Similar to Figure 6, Figure 8 shows the combustion state of the second embodiment, with (a) showing the early stage of combustion and (b) showing the later stage of combustion. Similar to Figure 7, Figure 9 also shows the change in the rate of heat release (ROHR) caused by combustion in the second embodiment. Note that the structure of the underlying engine 1 is the same as that of the first embodiment, and therefore will not be described here.

[0065] In this embodiment 2, the amount of hydrogen injected from fuel injector A30 is set to be less than the amount of hydrogen injected from fuel injector B31. Therefore, as shown in Figure 8(a), the pool of hydrogen γ injected from fuel injector A30 is smaller than the pool of hydrogen λ injected from fuel injector B31.

[0066] In this second embodiment, only the hydrogen reservoir γ injected from the fuel injection valve A30 is ignited P by the spark plug 32. In this case, too, the pressure rise can be suppressed more effectively than when the two hydrogen reservoirs γ and λ are ignited and burned simultaneously.

[0067] Then, as shown in (b), in this embodiment 2, the flame γ generated by the combustion of the hydrogen puddle γ travels halfway around the cylinder 10 and catches up with the hydrogen puddle λ injected from the fuel injection valve B31, ignites the hydrogen puddle λ P, and the hydrogen puddle λ also burns.

[0068] In this embodiment 2, as shown by the dashed line in Figure 9, the heat release rate (ROHR) is low when only the first hydrogen reservoir γ is burned, and the heat release rate (ROHR) is high when the second hydrogen reservoir λ is also burned.

[0069] This is a difference from embodiment 1. In this way, the rate of heat release (ROHR) when the first hydrogen reservoir γ is combusted is low, and the rate of heat release (ROHR) when the second hydrogen reservoir λ is also combusted is high, thereby achieving an ideal engine combustion state.

[0070] In other words, the theoretical combustion state of an engine is that all combustion occurs when the piston is at top dead center, and all of the explosion energy is converted into kinetic energy as the piston descends. However, in an actual engine, some of the explosion energy escapes as heat energy into the cylinder, piston, etc. For this reason, it is inefficient to have all combustion occur when the piston is at top dead center. Furthermore, if all combustion occurs near top dead center, the combustion temperature will rise sharply, resulting in increased NOx emissions.

[0071] Therefore, by generating more combustion when the piston descends from top dead center and the volume of the combustion chamber increases (by making the second rate of heat release (ROHR) greater than the first rate of heat release (ROHR)), the energy that was lost as thermal energy can be used as kinetic energy.In addition, by generating more combustion after top dead center, the combustion temperature can be suppressed, which also reduces the amount of NOx generated.

[0072] For these reasons, the combustion in this second embodiment makes it possible to obtain an ideal engine combustion state.

[0073] In this manner, in this embodiment, the amount of hydrogen pool γ injected from the fuel injection valve A30 is controlled to be less than the amount of hydrogen pool λ injected from the fuel injection valve B31.

[0074] As a result, the waveform of the rate of heat release (ROHR) caused by combustion is small in the first half of combustion and large in the second half of combustion.

[0075] Therefore, in the early stages of combustion when the piston is near top dead center and the combustion chamber is small, the amount of heat is reduced to limit thermal energy loss and the combustion temperature is also kept down, thereby reducing the generation of NOx.However, in the later stages of combustion when the piston is away from top dead center and the combustion chamber is large, the amount of heat is increased to maximize the effect of thermal energy, and the combustion temperature does not rise as much, making it less likely that NOx will be generated.

[0076] Therefore, a more ideal combustion state of the engine can be obtained.

[0077] (Other embodiments) Next, other embodiments will be described.

[0078] First, regarding the ignition means, a general spark plug is used in the first embodiment and the like, but a glow plug, a hot bulb, or the like may also be used as long as it is an ignition means that promotes the combustion of gas.

[0079] In addition, although in the above-described embodiment two ignition means are provided corresponding to the fuel injection valves, it may be one. Furthermore, when two ignition means are provided, the ignition means to be activated may be controlled to be switched, for example, at the timing of engine start or at regular intervals.

[0080] Furthermore, the gas to be burned is not limited to hydrogen, but may be any combustible gas such as methane, propane, or isobutane. [Industrial Applicability]

[0081] INDUSTRIAL APPLICABILITY As described above, the present invention is useful in gas engines that burn highly combustible gases such as hydrogen. [Explanation of symbols]

[0082] 1. Gas engine 10...Cylinder 30...Fuel injection valve A 31...Fuel injection valve B 32...Spark plug A (ignition means) 33...Spark plug B 40...Scavenging port α, β, γ, λ...Hydrogen accumulation (gas accumulation)

Claims

1. A crosshead type gas engine that burns highly combustible gas such as hydrogen, The engine is provided with a cylindrical cylinder whose interior serves as a combustion chamber, a plurality of fuel injection valves for injecting gas at positions spaced apart from one another in the circumferential direction are provided in the cylinder; a swirl flow generating means for generating a swirl flow in the air drawn into the cylinder, The plurality of fuel injection valves are configured to inject gas simultaneously near the top dead center of the piston, A plurality of gas pools injected by the fuel injection valve are configured to swirl due to the swirling flow of the air, At least one of the plurality of gas reservoirs is combusted by an ignition means, and the other gas reservoirs are combusted by the flame of the gas reservoir that has been combusted earlier and swirls in the circumferential direction. A crosshead gas engine.

2. the fuel injection valve is composed of a first fuel injection valve that injects fuel into a gas reservoir that is to be burned first, and a second fuel injection valve that injects fuel into a gas reservoir that is to be burned later, a control means for controlling the amount of gas injected from the first fuel injection valve to be less than the amount of gas injected from the second fuel injection valve; 2. A crosshead type gas engine according to claim 1.

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