JP2020073805A - engine - Google Patents

Abstract

To facilitate the maintenance of liquid fuel supply rail piping and pilot fuel supply rail piping, in an engine adapted to a premixed combustion system and a diffusion combustion system.SOLUTION: An engine 21 comprises a main fuel injection valve 79, a pilot fuel injection valve 82, liquid fuel supply rail piping 42, pilot fuel supply rail piping 47 and an exhaust manifold 44. The main fuel injection valve 79 supplies liquid fuel supplied from the liquid fuel supply rail piping 42 to a combustion chamber 110 at combustion by a diffusion combustion system. The pilot fuel injection valve 82 supplies pilot fuel supplied from the pilot fuel supply piping 47 to the combustion chamber 110 for the purpose of gas fuel ignition at combustion by a premixed combustion system. The liquid fuel supply rail piping 42 and the pilot fuel supply rail piping 47 are arranged in positions lower than the exhaust manifold 44.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a multifuel engine. In particular, it relates to the arrangement of pipes for supplying liquid fuel in the engine.

  Conventionally, one of a premixed combustion method in which a fuel gas such as natural gas is mixed with air and burned, or a diffusion combustion method in which a liquid fuel (fuel oil) such as heavy oil is diffused and burned is selectively selected. A so-called dual fuel engine that can be selectively driven is known. Patent Document 1 discloses an engine device that is an engine of this type.

  In the engine device of Patent Document 1, a liquid fuel supply rail pipe for supplying liquid fuel to a combustion chamber during combustion in a diffusion combustion system is provided on the right side of a crankshaft serving as an engine output shaft. .. In addition, the common rail pipe for supplying pilot fuel to the combustion chamber for the purpose of gas fuel ignition during combustion in the premixed combustion system is located on the left side of the crankshaft, just beside the exhaust manifold in plan view, and more specifically Specifically, it is provided above the exhaust branch pipe of the exhaust manifold.

JP, 2005-86728, A

  However, in the configuration of Patent Document 1, the liquid fuel supply rail pipes are arranged on the right side of the crankshaft, and the pilot fuel supply common rail pipes are arranged on the left side of the crankshaft. It was difficult to carry out maintenance from a common place, which led to a decrease in work efficiency.

  The present invention has been made in view of the above circumstances, and an object thereof is to facilitate maintenance of a liquid fuel supply rail pipe and a pilot fuel supply rail pipe.

Means and effects for solving the problems

  The problem to be solved by the present invention is as described above. Next, means for solving the problem and its effect will be described.

  According to the aspect of the present invention, an engine having the following configuration is provided. That is, this engine is compatible with a premixed combustion method in which gaseous fuel is mixed with air and then flown into the combustion chamber, and a diffusion combustion method in which liquid fuel is injected into the combustion chamber and burned. This engine includes a main fuel injection valve, a pilot fuel injection valve, a liquid fuel supply rail pipe, and a pilot fuel supply rail pipe. The main fuel injection valve supplies liquid fuel to the combustion chamber during combustion in the diffusion combustion method. The pilot fuel injection valve supplies pilot fuel to the combustion chamber for the purpose of gas fuel ignition during combustion in the premixed combustion method. This engine includes an exhaust manifold that collects exhaust gas generated by combustion in the combustion chamber and discharges it to the outside. The liquid fuel supply rail pipe and the pilot fuel supply rail pipe are arranged at a position lower than the exhaust manifold.

  As a result, the liquid fuel supply rail pipe and the pilot fuel supply rail pipe are arranged at a position lower than the exhaust manifold, so that if the fuel before being supplied to the combustion chamber leaks, the high temperature exhaust manifold You can eliminate the risk of contact with the surface and leading to a fire.

  The above engine preferably has the following configuration. That is, the engine further includes a fuel injection pump that supplies liquid fuel to the main fuel injection valve from the liquid fuel supply rail pipe. The fuel injection pump is provided at a position overlapping the liquid fuel supply rail pipe and the pilot fuel supply rail pipe in a side view of the engine.

  This facilitates the maintenance work of the liquid fuel supply rail pipe, the pilot fuel supply rail pipe, and the fuel injection pump.

  The above engine preferably has the following configuration. That is, the engine further includes a covering member. The covering member covers the liquid fuel supply rail pipe, the pilot fuel supply rail pipe, and the fuel injection pump.

  As a result, even if the fuel leaks from any of the liquid fuel supply rail pipe, the pilot fuel supply rail pipe, or the fuel injection pump, it is possible to prevent the fuel from being scattered around, and maintainability is improved. And safety is improved.

FIG. 3 is an explanatory view schematically showing an engine and a two-system fuel supply path according to an embodiment of the present invention. Rear view of the engine. The partial back surface sectional view showing the composition of the circumference of a combustion chamber in detail. Front view of the engine. Top view of the engine. Right side view of the engine. The typical front perspective view showing the liquid fuel supply course. Left side view of the engine. FIG. 3 is a perspective view of the engine showing a state where a part of the side cover and the heat shield cover are removed. The expansion perspective view of the engine which shows the state which removed the side cover.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view schematically showing an engine 21 and two systems of fuel supply paths 30 and 31 according to an embodiment of the present invention. FIG. 2 is a rear view of the engine 21. FIG. 3 is a rear partial cross-sectional view showing in detail the configuration around the combustion chamber 110. FIG. 4 is a front view of the engine 21. FIG. 5 is a plan view of the engine 21. FIG. 6 is a right side view of the engine 21. FIG. 7 is a schematic front perspective view showing the liquid fuel supply path. FIG. 8 is a left side view of the engine 21. FIG. 9 is a perspective view of the engine 21 showing a state where a part of the side cover 43 and the heat shield cover 45 are removed.

  The engine (multi-cylinder engine) 21 of the present embodiment shown in FIG. 1 includes a premixed combustion system in which gaseous fuel is mixed with air and then flows into a combustion chamber, and a diffusion combustion in which liquid fuel is injected and burned in the combustion chamber. It is a so-called dual fuel engine that can support both types. The engine 21 of this embodiment is installed on the inner bottom plate of the engine room of a ship via a base as a drive source for a propulsion and power generation mechanism of the ship not shown.

  A crankshaft 24 as an engine output shaft projects rearward from the rear end of the engine 21. A speed reducer (not shown) is connected to one end of the crankshaft 24 so that power can be transmitted. A propulsion shaft (not shown) of the ship is arranged with the speed reducer sandwiched therebetween so that the axis line of the propulsion shaft coincides with that of the crank shaft 24. A propeller for generating propulsive force of the ship is attached to the end of the propulsion shaft. The speed reducer has a PTO shaft, and a shaft drive generator (not shown) is connected to the PTO shaft so that power can be transmitted.

  With this configuration, the power of the engine 21 is branched and transmitted to the propulsion shaft and the shaft drive generator via the reduction gear. As a result, the propulsive force of the ship is generated, and the electric power generated by driving the shaft drive generator is supplied to the electric system inside the ship.

  Next, the engine 21 will be described in detail with reference to the drawings. The engine 21 is a dual-fuel engine as described above, and includes a premixed combustion method in which a fuel gas such as natural gas is mixed with air and burned, and a diffusion in which a liquid fuel (fuel oil) such as heavy oil is diffused and burned. Either the combustion method or the combustion method can be selected and driven.

  In the following description, the side connected to the speed reducer (the side on which the flywheel is arranged) is the rear side, the right side facing the front surface of the engine 21 is the right side, and the left side facing the front surface of the engine 21 is the left side. The front-rear and left-right positional relationship in the configuration 21 will be described. Therefore, the front-rear direction can be rephrased as a direction parallel to the axis of the crankshaft 24, and the left-right direction can be rephrased as a direction perpendicular to the axis of the crankshaft 24. However, this description does not limit the orientation of the engine 21, and the engine 21 can be installed in various orientations depending on the application and the like.

  As shown in FIG. 1, the engine 21 is connected with two fuel supply paths 30 and 31. A gas fuel tank 32 that stores liquefied natural gas (LNG) is connected to one fuel supply path 30, and a liquid fuel tank that stores marine diesel oil (MDO) is connected to the other fuel supply path 31. 33 is connected. With this configuration, one fuel supply path 30 supplies the fuel gas to the engine 21, and the other fuel supply path 31 supplies the fuel oil to the engine 21.

  The fuel supply path 30 includes, in order from the upstream side, a gas fuel tank 32 that stores a liquefied gaseous fuel, a vaporizer 34 that vaporizes the liquefied fuel in the gas fuel tank 32, and a fuel from the vaporizer 34 to the engine 21. And a gas valve unit 35 for adjusting the supply amount of gas.

  As shown in FIGS. 2 to 4, the engine 21 is an in-line multi-cylinder engine configured by assembling a cylinder head 26 on a cylinder block 25. As shown in FIGS. 2 and 4, the crankshaft 24 is rotatably supported at the lower portion of the cylinder block 25 with the axis 24c oriented in the front-rear direction.

  In the cylinder block 25, a plurality of (six in the present embodiment) cylinders are formed in a line (series) along the axis of the crankshaft 24. As shown in FIG. 3, a piston 78 is housed in each cylinder so as to be vertically slidable. The piston 78 is connected to the crankshaft 24 via a rod (not shown).

  As shown in FIGS. 5 and 6, a plurality of (six in the present embodiment) cylinder heads 26 are attached to the cylinder block 25 so as to cover each cylinder from above. The cylinder head 26 is provided for each cylinder and is fixed to the cylinder block 25 by using a head bolt 99. As shown in FIG. 3, in each cylinder, a combustion chamber 110 is formed in a space surrounded by the upper surface of the piston 78 and the cylinder head 26.

  As shown in FIG. 5, the plurality of head covers 40 are arranged in a line along the direction (front-rear direction) of the axis 24c of the crankshaft 24 on the cylinder head 26 so as to correspond to each cylinder. As shown in FIG. 3, a valve mechanism including a push rod and a rocker arm for operating the intake valve and the exhaust valve is housed inside each head cover 40. With the intake valve opened, intake air from the intake manifold 67 can be taken into the combustion chamber 110. With the exhaust valve opened, the exhaust gas from the combustion chamber 110 can be discharged to the exhaust manifold 44.

  As shown in FIG. 3, an upper end portion of a pilot fuel injection valve 82, which will be described later, is arranged near the left side of the head cover 40. When considering a virtual vertical plane P1 (see FIG. 7) including the axis 24c of the crankshaft 24, the pilot fuel injection valve 82 is viewed from one side (left side in the present embodiment) with respect to the virtual vertical plane P1. It is inserted inside the cylinder head 26 and extends obliquely downward toward the combustion chamber 110.

  In the following description, the position on one side / other side with respect to the virtual vertical plane P1 including the axis 24c of the crankshaft 24 may be expressed as one side / other side with respect to the crankshaft 24. .. The virtual vertical plane P1 can be considered to be an infinitely wide plane both in the direction of the axis 24c of the crankshaft 24 and in the vertical direction, but in FIG. An imaginary vertical plane P1 of only a part of is shown.

  As shown in FIGS. 2, 3 and 8, on the left side of the cylinder head 26 is a gas manifold 41 for distributing and supplying gas fuel to the combustion chamber 110 of each cylinder during combustion in a premixed combustion system. It is provided. The gas manifold 41 is arranged so as to extend in the front-rear direction along the left side surface of the cylinder head 26. A plurality (six in this embodiment) of gas branch pipes 41a corresponding to the combustion chambers 110 of the respective cylinders are connected to the gas manifold 41, and a tip end portion of the gas branch pipes 41a is connected to the gas branch pipe 41a as shown in FIG. A gas injector 98 for injecting gas fuel is provided. The tip of the gas injector 98 faces the intake branch pipe 67a formed inside the cylinder head 26 corresponding to the cylinder. By injecting the gas fuel from the gas injector 98, the gas fuel can be supplied to the intake branch pipe 67 a of the intake manifold 67.

  As shown in FIGS. 3, 7 and 9, on the right side of the cylinder block 25, a liquid fuel supply rail for distributing and supplying the liquid fuel to the combustion chamber 110 of each cylinder at the time of combustion in the diffusion combustion system. A pipe 42 is provided. The liquid fuel supply rail pipe 42 is arranged to extend in the front-rear direction along the right side surface of the cylinder block 25. The liquid fuel supplied to the liquid fuel supply rail pipe 42 is distributed and supplied to the fuel injection pump 89 provided corresponding to each cylinder. As shown in FIG. 3, a main fuel injection valve 79 that injects the liquid fuel supplied from the fuel injection pump 89 is arranged in each cylinder. The main fuel injection valve 79 is arranged so as to be vertically inserted into the cylinder head 26 from above, the upper end thereof is arranged inside the head cover 40, and the lower end thereof faces the combustion chamber 110 of the cylinder. The fuel injection pump 89 and the main fuel injection valve 79 are connected via a liquid fuel supply passage 106 formed in the cylinder head 26.

  A liquid fuel return collecting pipe 48 for collecting excess fuel returned from each fuel injection pump 89 is provided at a position near a lower portion of the liquid fuel supply rail pipe 42. The liquid fuel return collecting pipe 48 is arranged in parallel with the liquid fuel supply rail pipe 42, and is connected to the fuel injection pump 89. A fuel return pipe 115 for returning the liquid fuel to the liquid fuel tank 33 is connected to an end of the liquid fuel return collecting pipe 48.

  As shown in FIG. 3, FIG. 7 and FIG. 9, at the right side of the cylinder block 25 and above the liquid fuel supply rail pipe 42, the purpose is to ignite gas fuel during combustion in the premixed combustion system. As a pilot fuel supply rail pipe (pilot fuel supply common rail pipe) 47 for distributing and supplying pilot fuel to the combustion chamber 110 of each cylinder is provided. The pilot fuel supply rail pipe 47 is arranged so as to extend in the front-rear direction along the right side surface of the cylinder block 25. As shown in FIGS. 3 and 7, a pilot fuel injection valve 82 for injecting the liquid fuel (pilot fuel) supplied from the pilot fuel supply rail pipe 47 is arranged in each cylinder. The pilot fuel injection valve 82 is disposed so as to be obliquely inserted into the cylinder head 26 from above, the upper end thereof is disposed at a position just to the left of the head cover 40, and the lower end thereof faces the combustion chamber 110 of the cylinder. As shown in FIG. 7, a pilot fuel branch pipe 109 is provided so as to branch from the pilot fuel supply rail pipe 47 corresponding to each cylinder. The pilot fuel branch pipe 109 is arranged so as to pass between the head covers 40 arranged side by side, and is connected to the upper end portion of the pilot fuel injection valve 82. The pilot fuel branch pipe 109 is covered with a branch pipe cover 105 for preventing the leakage of the leaked fuel.

  As shown in FIG. 3, FIG. 7 and FIG. 9, a step is formed in the upper part of the right side surface of the engine 21 constituted by the cylinder block 25 and the cylinder head 26. The rail pipe 47, the liquid fuel supply rail pipe 42, and the fuel injection pump 89 are arranged. A side cover 43 is attached to the cylinder block 25 and the cylinder head 26 so as to cover the step portion. The pilot fuel supply rail pipe 47, the liquid fuel supply rail pipe 42, and the fuel injection pump 89 are covered with a side cover 43. Note that FIG. 9 illustrates a state in which a part of the side cover 43 is removed.

  As shown in FIGS. 2, 3 and 9, exhaust gas generated by combustion in the combustion chamber 110 of each cylinder is collected at a position on the upper left side of the cylinder head 26 and above the gas manifold 41. An exhaust manifold 44 for discharging to the outside is arranged in parallel with the gas manifold 41. The outer periphery of the exhaust manifold 44 is covered with a heat shield cover 45 (however, in FIG. 9, the heat shield cover 45 is removed). As shown in FIG. 3, an exhaust branch pipe 44a corresponding to each cylinder is connected to the exhaust manifold 44. The exhaust branch pipe 44a communicates with the combustion chamber 110 of each cylinder.

  An intake manifold 67 for distributing and supplying air (intake air) from the outside to the combustion chamber 110 of each cylinder is arranged parallel to the gas manifold 41 on the left side inside the cylinder block 25. As shown in FIG. 3, six intake branch pipes 67 a are formed inside the cylinder head 26 so as to branch from the intake manifold 67, and each intake branch pipe 67 a communicates with the combustion chamber 110.

  With this configuration, at the time of combustion in the diffusion combustion method, the air supplied from the intake manifold 67 to each cylinder is compressed from the main fuel injection valve 79 into the combustion chamber 110 at an appropriate timing when the piston 78 slides to compress the air. A quantity of liquid fuel is to be injected. By injecting the liquid fuel into the combustion chamber 110, the piston 78 reciprocates in the cylinder by the propulsive force obtained from the explosion that occurs in the combustion chamber 110, and the reciprocating motion of the piston 78 causes the piston 78 to reciprocate through the rod. It is converted into rotary motion to obtain power.

  On the other hand, at the time of combustion in the premixed combustion system, the gas fuel from the gas manifold 41 is injected from the gas injector 98 into the intake branch pipe 67a, so that the air supplied from the intake manifold 67 and the gas fuel are mixed. To be done. A small amount of pilot fuel is injected from the pilot fuel injection valve 82 into the combustion chamber 110 at an appropriate timing when the mixture of air and gas fuel introduced into the cylinder is compressed by the slide of the piston 78. Is ignited by. The piston 78 reciprocates in the cylinder by the propulsive force obtained by the explosion in the combustion chamber 110, and the reciprocating motion of the piston 78 is converted into the rotational motion of the crankshaft 24 via the rod to obtain power.

  Exhaust gas generated by the combustion is pushed out of the cylinder by the movement of the piston 78, collected in the exhaust manifold 44, and then discharged to the outside regardless of whether the combustion is performed by the diffusion combustion method or the premixed combustion method. It

  As shown in FIG. 4, a cooling water pump 53, a lubricating oil pump 55, and a fuel high-pressure pump 56 are provided on the front end surface (front surface) of the engine 21 so as to surround the front end portion of the crankshaft 24. There is. The high-pressure fuel pump 56 is arranged on the left side of the crankshaft 24. Further, a rotation transmission mechanism (not shown) that transmits the rotational power of the crankshaft 24 is provided at the front end portion of the engine 21. As a result, the rotational power from the crankshaft 24 is transmitted via the rotation transmission mechanism, so that the cooling water pump 53, the lubricating oil pump 55, and the fuel high-pressure pump 56 provided on the outer peripheral side of the crankshaft 24 are driven. Each is driven.

  As shown in FIG. 8, a lubricating oil cooler 58 and a lubricating oil strainer 59 are attached to the left side surface of the cylinder block 25. The lubricating oil supplied from the lubricating oil pump 55 is cooled by a lubricating oil cooler 58, purified by a lubricating oil strainer 59, and then supplied to each part of the engine 21.

  The cooling water sent from the cooling water pump 53 shown in FIG. 4 cools each cylinder of the engine 21, and then is collected in the cylinder head upper cooling water pipe 46 shown in FIG. 5 and the like.

  The intercooler 51 is arranged along the front end surface of the engine 21, and cools the air compressed by the compressor of the supercharger 49. As shown in FIG. 8, the cylinder block left cooling water pipe 60 extends rearward from the front of the cylinder block 25 along the gas manifold 41 to a position between the lubricating oil cooler 58 and the lubricating oil strainer 59. And extends to supply the cooling water to the lubricating oil cooler 58.

  As shown in FIGS. 5 and 9, the on-cylinder head cooling water pipe 46 is located at a position between the plurality of head covers 40, each of which is arranged above the cylinder head 26, and the exhaust manifold 44. It is arranged parallel to 44. The on-cylinder head cooling water pipe 46 is connected to a cooling water branch pipe provided corresponding to each cylinder, and a cooling water channel of each cylinder (a cooling water channel formed in the cylinder head 26) is connected via this cooling water branch pipe. Connected.

  The fuel high-pressure pump 56 shown in FIG. 4 is rotationally driven to increase the pressure of the fuel oil (liquid fuel) supplied from the liquid fuel tank 33 of FIG. It is sent to the pilot fuel supply rail pipe 47 via the pilot fuel supply main pipe 107 shown. A pilot fuel filter for filtering the fuel oil is provided in the middle of the fuel path from the liquid fuel tank 33 to the fuel high-pressure pump 56.

  When the fuel feed pump 165 shown in FIG. 1 is electrically driven, the fuel feed pump 165 sucks the fuel oil from the liquid fuel tank 33 and passes through the liquid fuel supply main pipe 108 shown in FIG. 7 and the like. And sends it to the liquid fuel supply rail pipe 42. A main fuel filter for filtering the fuel oil is provided in the middle of the fuel oil supply path from the liquid fuel tank 33 to the liquid fuel supply rail pipe 42.

  As shown in FIG. 7, the pilot fuel supply main pipe 107, the liquid fuel supply main pipe 108, and the fuel return pipe 115 are arranged immediately in front of the cylinder block 25 along the right side surface of the cylinder block 25. The pilot fuel supply main pipe 107, the liquid fuel supply main pipe 108, and the fuel return pipe 115 are provided in the cylinder block 25 via a plurality of clamp members 111 provided so as to project rightward from the front end surface of the cylinder block 25. It is arranged so as to extend in the vertical direction along the right side surface.

  On the front right side of the cylinder head 26, more specifically, on the right side surface of the intercooler 51, a machine-side operation control device 71 for controlling the start / stop of the engine 21 via a stay is provided. (See FIGS. 6 and 9). The machine-side operation control device 71 is provided with an operation unit such as a switch for accepting start / stop of the engine 21 by an operator, and a display for displaying an operating state of the engine 21. When the operator operates the machine-side operation control device 71, the engine 21 can be driven by either a premixed combustion system or a diffusion combustion system.

  Next, the arrangement of the liquid fuel supply pipes in the engine 21 will be described in more detail mainly with reference to FIG. 7.

  The liquid fuel supply path for supplying the liquid fuel to the combustion chamber 110 at the time of combustion in the diffusion combustion system is configured to include the liquid fuel supply main pipe 108, the liquid fuel supply rail pipe 42, and the like, as described above. .. The main fuel filter is provided in the middle of the liquid fuel supply main pipe 108. The main fuel filter is arranged near the right side of the front end surface of the engine 21. Further, the liquid fuel supply main pipe 108 extends vertically along the right side surface of the cylinder block 25 via a plurality of clamp members 111 provided so as to project rightward from the front end surface of the cylinder block 25. Be piped to. A liquid fuel supply rail pipe 42 is connected to the downstream side of the liquid fuel supply main pipe 108. The liquid fuel supply rail pipe 42 is covered by a side cover 43 while extending in the front-rear direction along the right side surface of the cylinder block 25.

  The liquid fuel pumped from the fuel feed pump 165 to the liquid fuel supply rail pipe 42 via the liquid fuel supply main pipe 108 is distributed to the fuel injection pump 89 provided corresponding to each cylinder. ing. The fuel injection pump 89 is covered with the side cover 43. The liquid fuel supplied to the fuel injection pump 89 is supplied to the main fuel injection valve 79 via the liquid fuel supply passage 106 formed inside the cylinder head 26, as shown in FIG.

  As described above, the liquid fuel supply path for supplying the liquid fuel to the combustion chamber 110 at the time of combustion in the diffusion combustion system as a whole is on the right side of the crankshaft 24 (a virtual vertical plane including the axis 24c of the crankshaft 24). It is located on the right side of P1). Therefore, the operator can access the liquid fuel supply path from the right side surface of the engine 21 and collectively perform maintenance of the liquid fuel supply main pipe 108, the liquid fuel supply rail pipe 42, the main fuel filter, and the like. In particular, the right side surface of the engine 21 is the side on which the machine-side operation control device 71 is conventionally arranged, and has a configuration that is easily accessible by the operator.

  As described above, the pilot fuel supply path for supplying the pilot fuel to the combustion chamber 110 for the purpose of igniting the gas fuel at the time of combustion in the diffusion combustion system is, as described above, the pilot fuel supply main pipe 107 and the pilot fuel supply rail pipe 47. It is configured with. A fuel high-pressure pump 56 is connected to the upstream side of the pilot fuel supply main pipe 107. A fuel path is connected to the upstream side of the high-pressure fuel pump 56, and the pilot fuel filter is provided in the middle of the fuel path. The upstream side of this fuel path is connected to the liquid fuel tank 33. The fuel high-pressure pump 56 and the pilot fuel filter are arranged on the right side of the front end surface of the engine 21. The pilot fuel supply main pipe 107 is arranged so as to extend vertically along the right side surface of the cylinder block 25 via the clamp member 111 used to support the liquid fuel supply main pipe 108. It In this way, since the pilot fuel supply main pipe 107 and the liquid fuel supply main pipe 108 are supported by the common clamp member 111, the number of parts can be reduced.

  A pilot fuel supply rail pipe 47 is connected to the downstream side of the pilot fuel supply main pipe 107. The pilot fuel supply rail pipe 47 is covered by the side cover 43 while extending in the front-rear direction along the right side surface of the cylinder block 25.

  The pilot fuel, which has been filtered by the pilot fuel filter and then pressure-fed from the high-pressure fuel pump 56 to the pilot fuel supply rail pipe 47 through the pilot fuel supply main pipe 107, is provided for each cylinder. It is distributed to the fuel branch pipe 109. The pilot fuel branch pipe 109 is arranged so as to pass through the space between the adjacent head covers 40. Although not shown in FIG. 7, the pilot fuel branch pipe 109 is covered with a branch pipe cover 105 from above. The pilot fuel supplied to the pilot fuel branch pipe 109 is injected at an appropriate timing from the pilot fuel injection valve 82 provided at the downstream end portion thereof.

  As described above, the pilot fuel supply path for supplying the pilot fuel to the combustion chamber 110 at the time of combustion in the premixed combustion system as a whole is on the right side (crank It is arranged on the right side of the virtual vertical plane P1 including the axis 24c of the shaft 24 (see FIG. 7). Therefore, the operator can easily access the pilot fuel supply path from the right side surface of the engine 21 and collectively perform maintenance of the pilot fuel supply main pipe 107, the pilot fuel supply rail pipe 47, the pilot fuel filter, and the like. is there. In this way, the maintenance related to the liquid fuel supply path (including the pilot fuel supply path) can be collectively performed from one side surface (the right side surface in this embodiment) of the engine 21, and the maintenance is easy for the operator. It is a layout.

  By the way, in the conventional dual fuel engine, the pilot fuel supply rail pipe 47 is not inside the side cover 43, but is located just beside the exhaust manifold 44 in plan view, more specifically, the exhaust gas of the exhaust manifold 44. It was provided so as to be exposed above the branch pipe 44a. The pilot fuel supply rail pipe 47 is generally a long product, and a seam or the like may be present in the middle of the pipe. However, fuel leaks from this seam, and the exhaust branch pipe 44 a of the exhaust manifold 44. Could have adhered to. Since high-temperature exhaust gas is flowing inside the exhaust manifold 44, it is not desirable for fuel to adhere to the exhaust branch pipe 44a and the like, which have such high temperatures.

  In this regard, in the present embodiment, the pilot fuel supply rail pipe 47 is arranged on the side opposite to the side on which the exhaust manifold 44 is arranged with respect to the crankshaft 24, and is distant from the exhaust manifold 44. There is. Therefore, even if the fuel leaks from the joint or the like of the pilot fuel supply rail pipe 47, it does not adhere to the surface of the high temperature exhaust manifold 44, and the risk of fire or the like can be eliminated.

  Moreover, since the pilot fuel supply rail pipe 47 of the present embodiment is arranged inside the side cover 43, even if the fuel leaks from the joint or the like of the pilot fuel supply rail pipe 47, the fuel will not leak to the surroundings. The engine 21 can be easily maintained without scattering.

  Next, a structure for supporting the liquid fuel supply rail pipe 42 will be described with reference to FIG. FIG. 10 is an enlarged perspective view of the engine 21 with the side cover 43 removed.

  As shown in FIG. 10, the liquid fuel supply rail pipe 42 includes a branch joint 92 arranged at a midway portion in the longitudinal direction thereof. One branch joint 92 is arranged for every two cylinders, and two pilot fuel branch pipes 109 are connected to the upper portions of the respective branch joints 92.

  As described above, the cylinder block 25 and the cylinder head 26 have a stepped portion, and the flat lower stay 95 is fixed to the cylinder block 25 so as to project upward from the bottom surface of the stepped portion. An L-shaped upper stay 96 is fixed to the cylinder head 26 so as to project laterally from the side wall of the stepped portion. The lower stay 95 and the upper stay 96 are fixed to the cylinder block 25 or the cylinder head 26 via bolts and nuts.

  A flat plate-shaped intermediate stay 97 is arranged so as to connect the lower stay 95 and the upper stay 96 to each other. The lower part of the intermediate stay 97 is fixed to the lower stay 95, and the upper part is fixed to the upper stay 96. The branch joint 92 is fixed to the intermediate stay 97. In addition, the above-mentioned fixing is performed through bolts and nuts.

  As described above, the lower stay 95 and the upper stay 96 are used to support the pilot fuel supply rail pipe 47 from above and below (from both the cylinder block 25 and the cylinder head 26), so that the rigidity of the support structure is improved. Therefore, the vibration of the pilot fuel supply rail pipe 47 can be reduced.

  As described above, the engine 21 of the present embodiment uses the premixed combustion method in which gaseous fuel is mixed with air and then flows into the combustion chamber 110, and the diffusion in which liquid fuel is injected into the combustion chamber 110 and burned. It can be used with the combustion method. The engine 21 includes a main fuel injection valve 79, a pilot fuel injection valve 82, a liquid fuel supply rail pipe 42, and a pilot fuel supply rail pipe 47. The main fuel injection valve 79 supplies liquid fuel to the combustion chamber 110 during combustion in the diffusion combustion system. The pilot fuel injection valve 82 supplies pilot fuel to the combustion chamber 110 for the purpose of gas fuel ignition at the time of combustion in the premixed combustion system. The liquid fuel supply rail pipe 42 is arranged on one side (right side) with respect to the virtual vertical plane P1 including the crankshaft 24 of the engine 21, and supplies the main fuel injection valve 79 with the liquid fuel. The pilot fuel supply rail pipe 47 is arranged on the same side as the liquid fuel supply rail pipe 42 with respect to the virtual vertical plane P1 and supplies the pilot fuel to the pilot fuel injection valve 82.

  As a result, both the maintenance of the liquid fuel supply rail pipe 42 and the maintenance of the pilot fuel supply rail pipe 47 are performed from one side (in the present embodiment, the right side face side) with respect to the crankshaft 24 of the engine 21. And maintenance is easy.

  Further, the engine 21 of the present embodiment is arranged on the opposite side (left side) to the liquid fuel supply rail pipe 42 with respect to the virtual vertical plane P1, and collects the exhaust gas generated by the combustion in the combustion chamber 110 and discharges it to the outside. The exhaust manifold 44 is further provided.

  As a result, the exhaust manifold 44 is arranged on the opposite side of the crankshaft 24 from the side on which the liquid fuel supply rail pipe 42 and the pilot fuel supply rail pipe 47 are arranged. Therefore, it is possible to prevent the fuel before being supplied to the combustion chamber 110 from being affected by the temperature of the exhaust gas flowing in the exhaust manifold 44 to become a high temperature and adversely affecting the performance of the engine.

  Further, the engine 21 of the present embodiment further includes a fuel injection pump 89 and a side cover 43 as a covering member. The fuel injection pump 89 is arranged on the same side (right side) as the liquid fuel supply rail pipe 42 with respect to the virtual vertical plane P1 and supplies fuel to the main fuel injection valve 79. The side cover 43 covers the liquid fuel supply rail pipe 42, the pilot fuel supply rail pipe 47, and the fuel injection pump 89.

  Accordingly, even if the fuel leaks from any of the liquid fuel supply rail pipe 42, the pilot fuel supply rail pipe 47, or the fuel injection pump 89, it is possible to prevent the fuel from scattering around. , Maintainability and safety are improved.

  Although the preferred embodiment of the present invention has been described above, the above configuration can be modified as follows, for example.

  In the above embodiment, the engine 21 is used as the drive source of the propulsion and power generation mechanism of the ship, but the present invention is not limited to this and may be a drive source used for other purposes.

  Although the liquid fuel supply rail pipe 42, the pilot fuel supply rail pipe 47, and the fuel injection pump 89 are provided along the right side surface of the engine 21 in the above embodiment, the present invention is not limited to this. Instead, for example, instead of this, the liquid fuel supply rail pipe 42, the pilot fuel supply rail pipe 47, and the fuel injection pump 89 may be provided along the left side surface of the engine 21.

21 Engine 24 Crankshaft 42 Liquid Fuel Supply Rail Piping 43 Side Cover (Coating Member)
44 Exhaust Manifold 45 Heat Shield Cover 47 Pilot Fuel Supply Rail Piping 79 Main Fuel Injection Valve 82 Pilot Fuel Injection Valve 89 Fuel Injection Pump 110 Combustion Chamber P1 Virtual Vertical Plane

Claims (3)

An engine capable of supporting a premixed combustion method in which a gaseous fuel is mixed with air and then flowing into a combustion chamber, and a diffusion combustion method in which a liquid fuel is injected into the combustion chamber and burned,
A main fuel injection valve that supplies liquid fuel to the combustion chamber during combustion in the diffusion combustion method;
A pilot fuel injection valve for supplying pilot fuel to the combustion chamber for the purpose of gas fuel ignition at the time of combustion in the premixed combustion method,
A liquid fuel supply rail pipe for supplying liquid fuel to the main fuel injection valve;
A pilot fuel supply rail pipe for supplying pilot fuel to the pilot fuel injection valve;
An exhaust manifold that collects exhaust gas generated by combustion in the combustion chamber and discharges the exhaust gas to the outside,
An engine comprising the rail pipe for supplying liquid fuel and the rail pipe for supplying pilot fuel at a position lower than the exhaust manifold. The engine according to claim 1,
A fuel injection pump for supplying liquid fuel to the main fuel injection valve from the liquid fuel supply rail pipe;
An engine characterized in that the liquid fuel supply rail pipe and the pilot fuel supply rail pipe are provided at a position overlapping the fuel injection pump in a side view of the engine. The engine according to claim 1 or 2, wherein
An engine comprising a covering member for covering the liquid fuel supply rail pipe and the pilot fuel supply rail pipe.

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