JP6675887B2 - Crosshead internal combustion engine - Google Patents

Description

  The present invention relates to a crosshead type internal combustion engine such as a diesel engine and a gas engine.

  Generally, an internal combustion engine such as a diesel engine or a gas engine that generates power by burning fuel in a cylinder has a crankshaft arranged below a plurality of cylinders along a cylinder arrangement direction. It is rotatably supported by the crankcase via a bearing. The crosshead type internal combustion engine is configured such that a frame is disposed above a base plate, and a combustion device is provided above the frame.

  The above-mentioned crosshead type internal combustion engine is a low-speed two-stroke diesel engine, and has a fuel oil mode for burning fuel oil and a fuel gas mode for burning fuel gas such as vaporized LNG. In this crosshead type internal combustion engine, a diffusion combustion type fuel injection valve that performs diffusion combustion of fuel gas when performing a fuel gas mode, and a premixed combustion type fuel injection valve that performs premixed combustion of fuel gas are provided. Have. As such a crosshead type internal combustion engine, for example, there is one described in Patent Document 1 below.

JP-A-2005-229973

  In the above-mentioned crosshead type internal combustion engine, gas fuel is required to reduce environmental load and fuel cost, but low NOx is expected while maintaining high thermal efficiency equivalent to that of the conventional crosshead type internal combustion engine. In order to adopt the premixed combustion that can be performed, it is necessary to avoid abnormal combustion such as premature ignition or knocking. By the way, when realizing premixed combustion, a gas injection valve is provided on the cylinder cover so that fuel can be injected when the piston moves near TDC. However, at a high crank angle that is suitable for creating a premixed gas, the premixed gas injected from the gas injection valve is difficult to spread over the entire combustion chamber because the combustion chamber is a region long in the cylinder axis direction, and the unevenness is uneven. Abnormal combustion such as premature ignition or knocking is likely to occur.

  The present invention is to solve the above-mentioned problem, and to provide a crosshead type internal combustion engine that enables uniform mixing of fuel and combustion gas to suppress occurrence of abnormal combustion such as premature ignition or knocking. With the goal.

  In order to achieve the above object, a crosshead type internal combustion engine of the present invention is provided with a cylinder liner having a cylindrical shape, a cylinder cover provided at one end of the cylinder liner, and a reciprocally movable interior of the cylinder liner. A piston, a combustion chamber defined by the cylinder liner, the cylinder cover, and the piston, an exhaust valve provided on the cylinder cover, and a valve provided on the other end of the cylinder liner and communicable with the combustion chamber. A scavenging port; a fuel injection valve for premixed combustion provided in the cylinder cover for injecting fuel gas into the combustion chamber; and a fuel injection for diffusion combustion provided in the cylinder cover for injecting fuel gas into the combustion chamber. Wherein the area of the injection port of the premixed combustion fuel injection valve is set larger than the area of the injection port of the diffusion combustion fuel injection valve. And it is characterized in that.

  Accordingly, in the premixed fuel gas mode, the high pressure fuel gas is injected from the premixed combustion fuel injection valve at the beginning of the compression stroke of the piston after the exhaust valve is closed and the scavenging port is closed. At this time, the fuel injection valve for premixed combustion injects the fuel gas in the longitudinal direction of the vertically elongated combustion chamber. In this premixed combustion fuel injection valve, the injection port area is set to be larger than the injection port area of the diffusion combustion fuel injection valve, so that the penetration force of the fuel gas injected into the combustion chamber is large, and the wide combustion chamber Injection is performed over the whole, and the mixing of the fuel gas with the combustion gas is promoted, so that a uniform air-fuel mixture can be formed over a wide range. As a result, it is possible to uniformly mix the fuel gas and the combustion gas, thereby suppressing the occurrence of abnormal combustion such as premature ignition or knocking.

  In the crosshead type internal combustion engine of the present invention, the number of injection ports of the fuel injection valve for premixed combustion is set to be smaller than the number of injection ports of the fuel injection valve for diffusion combustion, and one of the fuel injection valves for premixed combustion is provided. Is characterized in that the area of the injection port is set larger than the area of one injection port of the diffusion combustion fuel injection valve.

  Therefore, the number of injection ports of the fuel injection valve for premixed combustion is set to be smaller than the number of injection ports of the fuel injection valve for diffusion combustion, and a small amount of fuel gas is injected from the injection port of the fuel injection valve for premixed combustion. However, the opening / closing control for controlling the injection timing of the premixed combustion fuel injection valve does not become difficult, and the controllability of the premixed combustion fuel injection valve can be improved.

  The crosshead type internal combustion engine according to the present invention is characterized in that the total area of the injection ports of the fuel injection valve for premixed combustion and the total area of the injection ports of the fuel injection valve for diffusion combustion are set to be the same.

  Therefore, by setting the total area of the injection port of the fuel injection valve for premixed combustion and the total area of the injection port of the fuel injection valve for diffusion combustion to be the same, the injection amount of the fuel gas in the premixed fuel gas mode, the diffusion fuel gas mode, Can be easily adjusted to the same amount, and the controllability of the fuel injection control can be improved.

  In the crosshead type internal combustion engine of the present invention, the diffusion combustion fuel injection valve injects a fuel gas toward the top surface of the piston, and the premix combustion fuel injection valve faces the top surface of the piston. It is characterized by injecting the fuel gas in the direction that does not exist.

  Therefore, the premixed fuel gas mode and the diffusion fuel gas mode can be appropriately realized.

  In the crosshead type internal combustion engine of the present invention, the scavenging port is capable of imparting a swirling force to the combustion gas introduced into the combustion chamber, and the premixed combustion fuel injection valve is provided with a swirling direction of the combustion gas. The fuel gas is injected in a direction opposite to the above.

  Therefore, the combustion gas introduced from the scavenging port into the combustion chamber collides with the fuel gas injected from the premixed combustion fuel injection valve into the combustion chamber, and the mixing of the fuel gas with the combustion gas is promoted. A uniform mixture can be formed within the range.

  According to the crosshead type internal combustion engine of the present invention, since the area of the injection port of the fuel injection valve for premixed combustion is set to be larger than the area of the injection port of the fuel injection valve for diffusion combustion, uniform mixing of fuel and combustion gas is achieved. And the occurrence of abnormal combustion such as premature ignition or knocking can be suppressed.

FIG. 1 is a schematic diagram illustrating the overall configuration of a marine diesel engine as a crosshead type internal combustion engine according to the first embodiment. FIG. 2 is a schematic diagram illustrating a main part of the marine diesel engine. FIG. 3 is a longitudinal sectional view of the combustion chamber. FIG. 4 is a horizontal sectional view of the combustion chamber. FIG. 5 is a schematic diagram showing the injection state of the premixed gas. FIG. 6 is a schematic diagram illustrating a fuel oil injection state. FIG. 7 is a schematic diagram showing the state of injection of the diffusion gas. FIG. 8 is a horizontal sectional view of a combustion chamber of a marine diesel engine as a crosshead type internal combustion engine according to the second embodiment. FIG. 9 is a schematic perspective view of the combustion chamber.

  Hereinafter, preferred embodiments of a crosshead type internal combustion engine according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited by the embodiments, and when there are a plurality of embodiments, the embodiments include a combination of the embodiments.

[First Embodiment]
FIG. 1 is a schematic diagram illustrating the overall configuration of a marine diesel engine as a crosshead type internal combustion engine according to the first embodiment.

  In the first embodiment, as shown in FIG. 1, a diesel engine 10 is, for example, a two-stroke, one-cycle, uniflow scavenging type crosshead internal combustion engine used as a main engine for marine vessel propulsion. The diesel engine 10 includes a base plate 11 located below, a frame 12 provided on the base plate 11, and a combustion device 13 provided on the frame 12. The base plate 11, the frame 12, and the combustion device 13 are integrally fastened and fixed by a plurality of tension bolts 14 and nuts 15 extending vertically.

  The combustion device 13 has a cylinder in which a cylinder cover 17 is fixed to an upper end portion of a cylinder liner 16. The cylinder liner 16 and the cylinder cover 17 define a space, and a combustion chamber 19 is formed in the space by a piston 18 reciprocating up and down. Further, the cylinder cover 17 is provided with an exhaust valve 20 and can be opened and closed by a valve train 21. The exhaust valve 20 opens and closes the combustion chamber 19 and the exhaust port 22.

  Therefore, the fuel (for example, fuel oil and natural gas) supplied from a fuel injection pump (not shown) and the combustion gas (for example, air, EGR gas, or The mixed gas is burned when supplied. Then, the piston 18 moves up and down by the energy generated by this combustion. Further, at this time, when the combustion chamber 19 is opened by the exhaust valve 20, exhaust gas generated by combustion is pushed out to the exhaust port 22, and combustion gas is introduced into the combustion chamber 19 from a scavenging port (not shown).

  The upper end of the piston rod 23 is rotatably connected to the lower end of the piston 18. The base plate 11 forms a crankcase, and is provided with a bearing 25 that rotatably supports the crankshaft 24. The lower end of a connecting rod 27 is rotatably connected to the crankshaft 24 via a crank 26. In the frame 12, a pair of guide plates 28 extending in the up-down direction is fixed at predetermined intervals, and a crosshead 29 is supported between the pair of guide plates 28 so as to be vertically movable. In the crosshead 29, the lower end of the piston rod 23 and the upper end of the connecting rod 27 are rotatably connected respectively.

  Therefore, the piston 18 to which the energy has been transmitted from the combustion device 13 pushes down together with the piston rod 23 in the direction of the installation surface of the diesel engine 10 (the direction toward the base plate 11, that is, downward in the vertical direction). Then, the piston rod 23 pushes down the crosshead 29 in the same direction, and rotates the crankshaft 24 via the connecting rod 27 and the crank 26.

  FIG. 2 is a schematic diagram illustrating a main part of the marine diesel engine.

  The cylinder liner 16 is connected to a scavenging trunk 32 via a plurality of scavenging ports 31 provided at a lower portion, and is connected to an exhaust manifold 33 via an exhaust port 22 provided at an upper portion. The scavenging trunk 32 can supply air through an intake pipe (not shown). An exhaust valve 20 for discharging exhaust gas to an exhaust port 22 is provided at an upper portion of the cylinder cover 17. Further, the cylinder cover 17 is provided with an injector (fuel injection valve) 34 for injecting fuel into the combustion chamber 19.

  Therefore, when the piston 18 moves to the bottom dead center (the position indicated by the solid line in FIG. 2), the scavenging port 31 is opened, so that air in the scavenging trunk 32 is introduced from the scavenging port 31 into the combustion chamber 19, and the piston 18 rises. The communication between the scavenging port 31 and the combustion chamber 19 is blocked by the piston 18. Further, by closing the exhaust port 22 by the exhaust valve 20, the air in the combustion chamber 19 is compressed. When the piston 18 moves to the top dead center (the position indicated by the two-dot chain line in FIG. 2), the pressure in the combustion chamber 19 becomes a predetermined compression pressure, and the injector 34 injects fuel. Then, the air and fuel are mixed and burned in the combustion chamber 19, and the piston 18 is lowered by the combustion energy. At this time, exhaust gas (combustion gas) from the combustion chamber 19 is discharged to the exhaust port 22 by opening the exhaust port 22 by the exhaust valve 20.

  3 is a longitudinal sectional view of the combustion chamber, FIG. 4 is a horizontal sectional view of the combustion chamber, FIG. 5 is a schematic view showing an injection state of the premixed gas, and FIG. 6 is a schematic view showing an injection state of the fuel oil. FIG. 7 is a schematic view showing the state of injection of the diffusion gas.

  As shown in FIGS. 3 and 4, the injector 34 includes a premixed gas valve 41 as a premixed combustion fuel injection valve, a diffusion gas valve 42 as a diffusion combustion fuel injection valve, and a fuel oil injection valve (hereinafter, referred to as a fuel oil injection valve). , A fuel oil valve.) 43.

  As shown in FIGS. 3 and 4, two premixed gas valves 41 are provided on the outer peripheral side of the cylinder cover 17. The two premix gas valves 41 are arranged at positions facing each other with the center O of the cylinder cover 17 (center of the exhaust valve 20) interposed therebetween. In the present embodiment, two premixed gas valves 41 are provided, but one may be provided, or three or more may be provided.

  The premix gas valve 41 is connected to a fuel gas supply source (not shown), and injects fuel gas at a high pressure into a combustion chamber 19 formed by the cylinder liner 16, the cylinder cover 17, and the piston 18. As the fuel gas, for example, a hydrocarbon-based gas such as vaporized LNG is used.

  The premixed gas valve 41 is provided with one injection hole in a nozzle provided at the tip, and can inject fuel gas into the combustion chamber 19 from this one injection hole. In the present embodiment, as shown in FIG. 5, the premixed gas valve 41 injects the fuel gas G1 from the injection hole into the combustion chamber 19, and the direction of the injected fuel gas G1 is the direction of the piston 18, That is, the direction is toward the top surface of the piston 18 after the piston 18 closes the scavenging port 31. In the present embodiment, the number of injection holes in the premixed gas valve 41 is one, but may be two or more.

  The premixed gas valve 41 is activated when the diesel engine 10 is operated by premixed combustion, and is stopped without being activated during the diffusion combustion operation using the fuel gas G1 or the diffusion combustion operation using the fuel oil. The start and stop of the premixed gas valve 41 are performed by commands from a control device (not shown). The injection timing of the fuel gas G1 by the pre-mixed gas valve 41 is controlled by a control device (not shown) so that the fuel gas G1 does not leak out of the system from the exhaust valve 20. For example, 140 to 20 deg BTDC (Before Top Dead Center) Or less, preferably 100 to 60 degBTDC. Here, the timing at which the exhaust valve 20 closes is, for example, about 90 degBTDC. The injection period of the fuel gas G1 by the premixed gas valve 41 is, for example, 20 deg to 30 deg when the load on the diesel engine 10 is 100%.

  As shown in FIGS. 3 and 4, two diffusion gas valves 42 are provided on the outer peripheral side of the cylinder cover 17. The two diffusion gas valves 42 are arranged at positions facing each other with the center O of the cylinder cover 17 (center of the exhaust valve 20) interposed therebetween. Each of the diffusion gas valves 42 is arranged at a position shifted in the circumferential direction by a predetermined angle with respect to each of the premixed gas valves 41 described above. In this embodiment, two diffusion gas valves 42 are provided, but one or three or more diffusion gas valves 42 may be provided.

  The diffusion gas valve 42 is connected to a fuel gas supply source (not shown), like the premix gas valve 41, and injects fuel gas into the combustion chamber 19 formed by the cylinder liner 16, the cylinder cover 17, and the piston 18. . As the fuel gas, for example, a hydrocarbon-based gas such as vaporized LNG is used.

  The diffusion gas valve 42 is provided with a plurality of (four in this embodiment) injection holes in a nozzle provided at the tip, and can inject fuel gas into the combustion chamber 19 from these four injection holes. it can. In this embodiment, the diffusion gas valve 42 injects the fuel gas G2 from the four injection holes into the combustion chamber 19, as shown in FIG. The direction is a horizontal direction or a direction slightly downward from the horizontal direction and does not face the surface of the piston 18 so that diffusion combustion is performed in the combustion chamber 19 which has been narrowed by rising to the vicinity of the top dead center. In the present embodiment, the number of injection holes in the diffusion gas valve 42 is four, but may be three or less, or five or more.

  The diffusion gas valve 42 is activated when the diesel engine 10 is operated by diffusion combustion, and is not activated during the premix combustion operation using the fuel gas G2 or the diffusion combustion operation using fuel oil, and is stopped. The start and stop of the diffusion gas valve 42 are performed by commands from a control device (not shown). The injection period of the fuel gas G2 by the diffusion gas valve 42 is controlled by a control device (not shown). For example, when the load of the diesel engine 10 is 100%, the injection period is 20 deg to 30 deg.

  As shown in FIGS. 3 and 4, two fuel oil valves 43 are provided on the outer peripheral side of the cylinder cover 17. The two fuel oil valves 43 are arranged at positions facing each other with the center O of the cylinder cover 17 (center of the exhaust valve 20) interposed therebetween. The fuel oil valve 43 is located on the outer peripheral side of the exhaust valve 20 and on the inner peripheral side of the premixed gas valve 41 and the diffusion gas valve 42. Each fuel oil valve 43 is arranged at a position shifted in the circumferential direction by a predetermined angle with respect to each diffusion gas valve 42 described above. That is, the premix gas valve 41, the diffusion gas valve 42, and the fuel oil valve 43 are arranged in this order along the circumferential direction of the cylinder cover 17. In the present embodiment, two fuel oil valves 43 are provided, but may be one, or three or more.

  The fuel oil valve 43 is connected to a fuel oil supply source (not shown), and injects fuel oil into a combustion chamber 19 formed by the cylinder liner 16, the cylinder cover 17, and the piston 18. As this fuel oil, for example, heavy oil such as C heavy oil is used.

  The fuel oil valve 43 is provided with a plurality of (four in this embodiment) injection holes in a nozzle provided at the tip, and can inject fuel oil into the combustion chamber 19 from these four injection holes. it can. In the present embodiment, the fuel oil valve 43 injects the fuel oil G3 from the four injection holes as shown in FIG. 6, and the direction of the injected fuel oil G3 is such that the piston 18 is close to the vicinity of the top dead center. The horizontal direction or the direction slightly downward from the horizontal direction, and the direction not facing the top surface of the piston 18 so that ignition or diffusion combustion is performed in the combustion chamber 19 that has been raised and narrowed. In the present embodiment, the number of injection holes in the fuel oil valve 43 is four, but may be three or less, or five or more.

  When operating the diesel engine 10 by diffusion combustion with the fuel oil G3, the fuel oil valve 43 operates so as to inject the fuel oil G3 for diffusion combustion (so-called oil-only combustion operation). During the mixed combustion operation and the diffusion combustion operation using the fuel gas G2, the operation is performed so as to inject pilot oil for ignition. The operation of the fuel oil valve 43 is performed by a command from a control device (not shown).

  The injector 34 of the present embodiment configured as described above includes a premixed gas valve 41, a diffusion gas valve 42, and a fuel oil valve 43, and the area of the injection port of the premixed gas valve 41 is Is larger than the area of the nozzle.

  In the present embodiment, the number of nozzles of the premix gas valve 41 is one, the number of nozzles of the diffusion gas valve 42 is four, and the number of nozzles (one) of the premix gas valve 41 is the number of nozzles of the diffusion gas valve 42. Is set to be less than the number (4). The area of one injection port of the premix gas valve 41 is set to be larger than the area of one injection port of the diffusion gas valve 42. In this case, the relationship between the number of injection ports of the premixed gas valve 41 and the number of injection ports of the diffusion gas valve 42 is one and four in the present embodiment. Good.

  However, the area of one injection port of the premix gas valve 41 and the total area of the four injection ports of the diffusion gas valve 42 are desirably set to the same area.

In this case, when one premixed gas valve 41 and one diffusion gas valve 42 are disposed on the cylinder cover 17, the premixed gas valve 41 has one injection port and the diffusion gas valve 42 has four injection ports. When the number is set, the injection port area ratio A of the premixed gas valve 41 is set by the following equation. Here, the cross-sectional area of the combustion chamber 19 is the area inside the cylinder liner 16.
Injection area ratio A = 1 area of one injection port / cross-sectional area of combustion chamber At this time, it is desirable that the injection opening area ratio A of the premixed gas valve 41 is 3.0E-05 or more.

  The diesel engine 10 of the present embodiment configured as described above mainly uses the premixed gas valve 41 and uses the fuel oil valve 43 for pilot use, and uses the diffusion gas valve 42 mainly and uses the fuel oil mode. There is a diffusion fuel gas mode in which the valve 53 is used for pilot use and a diffusion fuel oil mode in which the fuel oil valve 43 is exclusively used.

  The premixed fuel gas mode is used, for example, when a ship navigates in the ECA because the NOx emission amount is small. The diffusion fuel gas mode has higher combustion stability than the premixed fuel gas mode, but generates a larger amount of NOx than the premixed fuel gas mode. Therefore, the diffusion fuel gas mode is used, for example, when a ship travels outside the ECA. Also, the diffusion fuel gas mode can be used in place of the premixed fuel gas mode when combustion stability is required within a predetermined time within the ECA within a range not exceeding the NOx regulation amount. In the diffusion fuel oil mode, SOx derived from fuel oil is generated more than when fuel gas is used. For example, when navigating in a sea area where SOx emission regulations are relatively relaxed, high combustion stability is required. It is used when it is better to use fuel oil than fuel gas.

[Premixed fuel gas mode]
In the premixed fuel gas mode, as shown in FIGS. 3 to 5, the high pressure is applied from the premixed gas valve 41 at the beginning of the compression stroke after the exhaust valve 20 is closed and the piston 18 closes the scavenging port 31. The fuel gas G <b> 1 is injected toward the top of the piston 18. At this time, the premixed gas valve 41 injects the fuel gas G1 from the upper cylinder cover 17 toward the top surface of the lower piston 18, so that the combustion becomes vertical after the piston 18 closes the scavenging port 31. The fuel gas G1 can be injected entirely by effectively using the longitudinal direction of the chamber 19, and the mixing of the fuel gas with the air is promoted.

  Further, in this embodiment, since the area of the injection port of the premixed gas valve 41 is set to be larger than the area of the injection port of the diffusion gas valve, the penetration force of the fuel gas G1 injected into the combustion chamber 19 is higher than in the related art. Becomes larger. Therefore, the fuel gas G1 from the premixed gas valve 41 is distributed throughout the wide combustion chamber 19 which is elongated vertically, and the mixing of the fuel gas with the air is promoted, and the air-fuel mixture is uniform over a wide range. Can be formed.

  After a premixed gas is formed in the combustion chamber 19 by the fuel gas G1 injected from the premixed gas valve 41, the piston 18 moves upward to compress the premixed gas. Then, when the piston 18 reaches the vicinity of the top dead center, the pilot oil G3 is injected from the fuel oil valve 43 to ignite. Premixed combustion is performed while the flame formed by the ignition propagates in the premixed gas, the combustion and expansion strokes are performed, and the piston 18 moves downward.

  In the diffusion fuel gas mode, as shown in FIGS. 3, 4 and 7, in the compression stroke after the exhaust valve 20 is closed and the piston 18 closes the scavenging port 31, only the air introduced from the scavenging port 31 is removed. Compress. Then, when the piston 18 reaches the vicinity of the top dead center, the fuel oil G3 is injected from the fuel oil valve 43 as pilot oil, and simultaneously or immediately after the pilot oil G3, the fuel gas whose pressure is increased from the diffusion gas valve 42. Inject G2. Thereby, diffusion combustion is performed in the combustion chamber 19 in response to the injection of the fuel gas G2, and the piston 18 is pushed down by the expansion stroke.

  In the diffusion fuel oil mode, as shown in FIG. 3, FIG. 4, and FIG. 6, the operation is almost the same as in the diffusion fuel gas mode, and the exhaust valve 20 is closed to compress the air as the piston 18 rises. Then, near the top dead center of the piston 18, the fuel oil G3 is injected from the fuel oil valve 43 at a high pressure to perform diffusion combustion, and the piston 18 descends by the expansion stroke due to the diffusion combustion.

  Thus, in the cross-head type internal combustion engine of the first embodiment, the cylinder liner 16, the cylinder cover 17, the piston 18, the combustion chamber 19 defined by the cylinder liner 16, the cylinder cover 17, and the piston 18 , An exhaust valve 20 provided on the cylinder cover 17, a scavenging port 31 provided below the cylinder liner 16 and capable of communicating with the combustion chamber 19, a premix gas valve 41 and a diffusion gas valve 42 provided on the cylinder cover 17. And the area of the injection port of the premix gas valve 41 is set to be larger than the area of the injection port of the diffusion gas valve 42.

  Therefore, in the premixed fuel gas mode, the high pressure fuel gas G1 is injected from the premixed gas valve 41 at the beginning of the compression stroke of the piston 18 after the exhaust valve 20 is closed and the scavenging port 31 is closed. At this time, since the area of the injection port of the premixed gas valve 41 is set to be larger than the area of the injection port of the diffusion gas valve 42, the penetration force of the fuel gas G1 injected into the combustion chamber 19 is large. Therefore, the fuel gas G1 from the premixed gas valve 41 is injected over the entire vertically long combustion chamber 19, and the mixing of the fuel gas G1 with the air is promoted, and a uniform mixture over a wide range is produced. Can be formed. As a result, uniform mixing of the fuel gas G1 and the air is enabled, and occurrence of abnormal combustion such as premature ignition or knocking can be suppressed.

  In the crosshead type internal combustion engine of the first embodiment, the number of injection ports of the premix gas valve 41 is set to be smaller than the number of injection ports of the diffusion gas valve 42, and the area of one injection port of the premix gas valve 41 is set to The area of one injection port of the valve 42 is set to be larger. Therefore, since the number of injection ports of the premix gas valve 41 is small, even when it is necessary to inject a small amount of the fuel gas G1 from the injection port of the premix gas valve 41, an electromagnetic valve is used as the premix gas valve 41. Even if it is applied, the opening and closing control for controlling the injection timing of the solenoid valve does not become difficult, and the controllability of the premixed gas valve 41 can be improved.

  In the crosshead type internal combustion engine of the first embodiment, the total area of the injection ports of the premixed gas valve 41 and the total area of the injection ports of the diffusion gas valve 42 are set to be the same. Therefore, it becomes easy to adjust the injection amount of the fuel gas G1, G2 to the same amount in the premixed fuel gas mode, the diffusion fuel gas mode, and the controllability of the fuel injection control.

[Second embodiment]
FIG. 8 is a horizontal sectional view of a combustion chamber of a marine diesel engine as a crosshead type internal combustion engine according to the second embodiment, and FIG. 9 is a schematic perspective view of the combustion chamber. Note that members having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

  In the second embodiment, as shown in FIGS. 8 and 9, the cylinder liner 16 is provided with a plurality of scavenging ports 31 at the lower part, the cylinder cover 17 is fixed at the upper part, and the exhaust valve 20 is attached to the cylinder cover 17. An injector 34 is provided. The injector 34 includes a premix gas valve 41, a diffusion gas valve 42, and a fuel oil valve 43. The premix gas valve 41, the diffusion gas valve 42, and the fuel oil valve 43 are provided on the outer peripheral side of the cylinder cover 17 at predetermined intervals in the circumferential direction along the circumferential direction.

  The area of the injection port of the premix gas valve 41 is set to be larger than the area of the injection port of the diffusion gas valve 42. That is, the number of nozzles of the premix gas valve 41 is one, the number of nozzles of the diffusion gas valve 42 is four, and the number of nozzles (one) of the premix gas valve 41 is equal to the number of nozzles of the diffusion gas valve 42 ( 4). The area of one injection port of the premix gas valve 41 is set to be larger than the area of one injection port of the diffusion gas valve 42.

  Further, in the present embodiment, the plurality of scavenging ports 31 are arranged in a tangential direction with respect to the combustion chamber 19 (cylinder cover 17), and exert a swirling force on the air introduced into the combustion chamber 19. The swirl S can be generated by giving. The swirl S flows in a clockwise direction when the combustion chamber 19 is viewed from above. On the other hand, the premixed gas valve 41 injects the fuel gas G1 in a direction opposite to the turning direction of the swirl S of the air. That is, the premixed gas valve 41 has an injection port opened in a direction opposite to the swirling direction of the swirl S of air, and injects the fuel gas G1 from one injection port against the swirl S.

  Although the premixed gas valves 41 are arranged at positions opposing each other with the center O of the cylinder cover 17 (center of the exhaust valve 20) interposed therebetween, the fuel gas G1 is injected from both the premixed gas valves 41. The direction may be opposite to the swirl S of the air, or the injection direction of the fuel gas G1 from one premixed gas valve 41 may be opposite to the swirl S of the air.

  Therefore, in the premixed fuel gas mode, at the beginning of the compression stroke after the exhaust valve 20 is closed and the piston 18 closes the scavenging port 31, the fuel gas G1, which has been increased in pressure from the premixed gas valve 41, is supplied to the piston 18. Injected towards the top. At this time, the premixed gas valve 41 injects the fuel gas G1 from the upper cylinder cover 17 toward the top surface of the lower piston 18, so that the combustion becomes vertical after the piston 18 closes the scavenging port 31. The fuel gas G1 can be injected entirely by effectively using the longitudinal direction of the chamber 19, and the mixing of the fuel gas with the air is promoted.

  Further, in the present embodiment, the area of the injection port of the premixed gas valve 41 is set to be larger than the area of the injection port of the diffusion gas valve, and the fuel gas G1 is injected in a direction opposite to the swirling direction of the air swirl S. Then, the penetration force of the fuel gas G1 injected into the combustion chamber 19 increases, and the fuel gas G1 collides with the swirl S of the air. The fuel gas G1 spreads over the air, and the mixing of the fuel gas with the air is promoted, and a uniform air-fuel mixture can be formed over a wide range.

  As described above, in the crosshead type internal combustion engine of the second embodiment, the scavenging port 31 can apply a swirling force to the air introduced into the combustion chamber 19, and the premix gas valve 41 controls The fuel gas G1 is injected in a direction opposite to the turning direction.

  Therefore, the swirl S of the air introduced from the scavenging port 31 into the combustion chamber 19 collides with the fuel gas G1 injected from the premix gas valve 41 into the combustion chamber 19, and the mixing of the fuel gas G1 with the air is promoted. A uniform air-fuel mixture can be formed over a wide range.

10. Diesel engine (crosshead internal combustion engine)
13 Combustion device 16 Cylinder liner 17 Cylinder cover 18 Piston 19 Combustion chamber 20 Exhaust valve 31 Scavenging port 32 Scavenging trunk 34 Injector 41 Premixed gas valve (premixed combustion fuel injection valve)
42 Diffusion gas valve (diffusion combustion fuel injection valve)
43 Fuel oil valve G1, G2 Fuel gas G3 Pilot oil (fuel oil)
S swirl

Claims (5)

A cylinder liner having a cylindrical shape,
A cylinder cover provided at one end of the cylinder liner,
A piston provided reciprocally in the cylinder liner,
A combustion chamber defined by the cylinder liner, the cylinder cover, and the piston;
An exhaust valve provided on the cylinder cover;
A scavenging port provided at the other end of the cylinder liner and capable of communicating with the combustion chamber;
A fuel injection valve for premixed combustion that is provided on the cylinder cover, has one or more injection ports, and injects fuel gas into the combustion chamber;
A fuel injection valve for diffusion combustion that has a plurality of injection ports provided on the cylinder cover and injects fuel gas into the combustion chamber;
With
In the premixed fuel gas mode, the premixed combustion fuel injection valve injects a fuel gas at an early stage of a compression stroke,
In the diffusion fuel gas mode, only air is compressed in the compression stroke, and then the diffusion combustion fuel injector injects the fuel gas,
The area of one injection port of the fuel injection valve for premixed combustion is set to be larger than the area of one injection port of the fuel injection valve for diffusion combustion.
A crosshead type internal combustion engine characterized by the above-mentioned.   The number of injection ports of the fuel injection valve for premixed combustion is set to be smaller than the number of injection ports of the fuel injection valve for diffusion combustion, and the area of one injection port of the fuel injection valve for premixed combustion is reduced by the area of the fuel for diffusion combustion. 2. The crosshead type internal combustion engine according to claim 1, wherein the area is set to be larger than the area of one injection port of the injection valve.   The crosshead type according to claim 1 or 2, wherein the total area of the injection ports of the fuel injection valve for premixed combustion and the total area of the injection ports of the fuel injection valve for diffusion combustion are set to be the same. Internal combustion engine. The fuel injection valve for premixed combustion injects fuel gas toward the top surface of the piston, and the fuel injection valve for diffusion combustion injects fuel gas in a direction not toward the top surface of the piston. The crosshead type internal combustion engine according to any one of claims 1 to 3, characterized in that:   The scavenging port is capable of imparting a swirling force to the combustion gas introduced into the combustion chamber, and the premixed combustion fuel injector injects the fuel gas in a direction opposite to a direction in which the combustion gas is swirled. The crosshead type internal combustion engine according to any one of claims 1 to 4, characterized in that:

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