JP2018009522A - Multi-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reasonably connect a rail pipe for pilot fuel supply and a pilot fuel injection valve, in a dual-fuel type multi-cylinder engine.SOLUTION: In an engine 21, a plurality of head covers 40 covering a valve mechanism are arranged side by side in a direction of an axial line 24c of a crank shaft. A pilot fuel injection valve 82 is arranged more on one side from a virtual perpendicular plane P1 including the axial line 24c, for each cylinder, and supplies pilot fuel for gas fuel ignition during combustion in premix combustion system. A rail pipe 47 for pilot fuel supply is arranged on a side opposite to the one side with respect to the virtual perpendicular plane P1. Head bolts for fixing a cylinder head 26 to a cylinder block 25 are arranged so as to form two rows in a space between adjacent head covers 40, and a pilot fuel branch pipe 109 passes above head bolts in only one row out of the two rows to connect the rail pipe 47 for pilot fuel supply and the pilot fuel injection valve 82.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a multi-cylinder engine. In detail, it is related with arrangement | positioning of the piping for pilot fuel supply in a multicylinder engine.

  As a conventional multi-cylinder engine, for example, a premix combustion method in which fuel gas such as natural gas is mixed with air and burned, and a diffusion combustion method in which liquid fuel (fuel oil) such as heavy oil is diffused and burned A so-called dual fuel engine that can be driven by selecting either one is known. Patent Document 1 discloses an engine device that is this type of multi-cylinder engine.

  In the engine device of Patent Document 1, a common rail pipe (pilot fuel supply common rail pipe) for supplying pilot fuel to the combustion chamber for the purpose of gas fuel ignition at the time of combustion in the premixed combustion system is connected to the crankshaft. It is provided on the left side, just on the left side of the exhaust manifold in plan view, more specifically, at a position above the exhaust branch pipe of the exhaust manifold.

JP2015-86728A

  However, in the configuration of Patent Document 1, the pilot fuel supply common rail piping is provided in the vicinity of the exhaust manifold. Therefore, if the pilot fuel before being supplied to the combustion chamber leaks, There was a risk of contact with the surface and fire.

  In order to dispose the pilot fuel supply common rail piping away from the exhaust manifold, the pilot fuel supply common rail piping should be disposed on the opposite side of the crankshaft from which the exhaust manifold is disposed. Can be considered.

  However, in that case, conventionally, the pilot fuel injection valve that supplies pilot fuel to the combustion chamber is combusted so that the front end portion of the head cover on the upper side of the cylinder head enters the lower side of the head cover from the side where the exhaust manifold is disposed. Since it is inserted in the room, it is difficult to rationally arrange the branch pipe connecting the common rail pipe for supplying the pilot fuel and the pilot fuel injection valve.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a pilot fuel supply rail pipe even when the pilot fuel injection valve is disposed on the side opposite to the side where the pilot fuel injection valve is inserted into the head cover. It is an object of the present invention to provide a branch pipe configuration that rationally connects a pilot fuel supply rail pipe and a pilot fuel injection valve.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to an aspect of the present invention, a multi-cylinder engine having the following configuration is provided. That is, this multi-cylinder engine is compatible with a premixed combustion method in which gaseous fuel is mixed with air and then flows into the combustion chamber, and a diffusion combustion method in which liquid fuel is injected into the combustion chamber and burned. . The multi-cylinder engine includes a head cover, a pilot fuel injection valve, a pilot fuel supply rail pipe, a plurality of head bolts, and a pilot fuel branch pipe. The head cover is provided for each cylinder so as to cover the valve mechanism of the multi-cylinder engine, and a plurality of the head covers are arranged side by side in the axial direction of the crankshaft of the multi-cylinder engine. The pilot fuel injection valve is disposed for each cylinder so as to extend obliquely downward from one side of the virtual vertical plane including the axis of the crankshaft toward the combustion chamber, and combustion in the premixed combustion system Sometimes pilot fuel is supplied to the combustion chamber for the purpose of gas fuel ignition. The pilot fuel supply rail pipe is disposed on the opposite side to the one side with respect to the virtual vertical plane, and is commonly used by the plurality of cylinders for supplying pilot fuel to the pilot fuel injection valve. The head bolts are arranged so as to form a plurality of rows arranged in the same direction as the direction in which the head covers are arranged between the adjacent head covers in a plan view, and the cylinder head and the cylinder block of the multi-cylinder engine. Fix it. The pilot fuel branch pipe branches off from the pilot fuel supply rail pipe and passes above the head bolt of only a part of the plurality of rows between the adjacent head covers, and the pilot fuel Connect to the injection valve.

  Thereby, the pilot fuel branch pipe can be rationally arranged by utilizing the space between the adjacent head covers. In addition, since a lifting jig can be easily mounted on the head bolts in the row where the pilot fuel branch pipe does not pass above, it is possible to lift the multi-cylinder engine via the head bolt for engine installation or the like. Easy.

  The multi-cylinder engine preferably has the following configuration. That is, spaces are formed between the head covers adjacent to each other among the plurality of head covers. In the direction in which the head covers are arranged, the space through which the pilot fuel branch pipe passes and the space through which the pilot fuel branch pipe does not pass are alternately arranged.

  Thereby, since the degree of detouring of the pilot fuel branch pipe can be reduced, the length can be shortened.

  In the multi-cylinder engine, it is preferable that the plurality of pilot fuel branch pipes are arranged so as to pass above the head bolts in one row.

  As a result, the number of head bolt rows on which lifting jigs can be mounted can be increased, which makes it easier to lift a multi-cylinder engine. Further, by supporting a plurality of pilot fuel branch pipes with a common member, the configuration can be simplified and made compact.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows schematically the engine which concerns on one Embodiment of this invention, and two fuel supply paths. The rear view of an engine. The partial back sectional view which shows the structure of the periphery of a combustion chamber in detail. The front view of an engine. The top view of an engine. The right view of an engine. The typical front perspective view which shows a liquid fuel supply path | route. The left view of an engine. The perspective view of the engine which shows a mode when a part of side cover and a heat shield cover are removed. The perspective view which shows the structure of a cylinder head upper part. The perspective view which shows the structure of a pilot fuel branch pipe support structure. The perspective view which shows a mode that the jig | tool for lifting was attached to the head bolt.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram schematically showing an engine 21 and two 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 partial rear cross-sectional view showing the configuration around the combustion chamber 110 in detail. 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 when a part of the side cover 43 and the heat shield cover 45 are removed.

  The engine (multi-cylinder engine) 21 of this embodiment shown in FIG. 1 has a premixed combustion method in which gaseous fuel is mixed with air and then flows into the combustion chamber, and diffusion combustion in which liquid fuel is injected into the combustion chamber for combustion. This is a so-called dual fuel engine that can be used for any of the above systems. The engine 21 according to the present embodiment is installed on the inner bottom plate of the engine room of the ship via a base as a drive source of a ship propulsion and power generation mechanism (not shown).

  A crankshaft 24 as an engine output shaft protrudes rearward from the rear end portion of the engine 21. A reduction gear (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 so that the crankshaft 24 and the axis line coincide with each other with the speed reducer interposed therebetween. A propeller that generates a 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 speed reducer. Thus, the propulsive force of the ship is generated, and the electric power generated by driving the shaft drive generator is supplied to the electrical system in 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 a premixed combustion method in which fuel gas such as natural gas is mixed with air and burned, and diffusion in which liquid fuel (fuel oil) such as heavy oil is diffused and burned. Either of the combustion methods can be selected and driven.

  In the following, the front-rear and left-right positional relationships in the configuration of the engine 21 will be described with the side connected to the reduction gear (the side on which the flywheel is disposed) being the rear side. 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.

  As shown in FIG. 1, two systems of fuel supply paths 30 and 31 are connected to the engine 21. A gas fuel tank 32 for storing liquefied natural gas (LNG) is connected to one fuel supply path 30, and a liquid fuel tank for storing 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 fuel gas to the engine 21, and the other fuel supply path 31 supplies fuel oil to the engine 21.

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

  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 supported on the lower portion of the cylinder block 25 so as to be rotatable with the axis 24 c directed in the front-back direction.

  The cylinder block 25 is formed with a plurality of (six in this embodiment) cylinders arranged in a line (in series) along the axis of the crankshaft 24. As shown in FIG. 3, a piston 78 is accommodated in each cylinder so as to be slidable in the vertical direction. The piston 78 is connected to the crankshaft 24 through a rod (not shown).

  As shown in FIGS. 5 and 6, a plurality of (six in this embodiment) cylinder heads 26 are attached to the cylinder block 25 so as to cover each cylinder from above. A cylinder head 26 is provided for each cylinder, and is fixed to the cylinder block 25 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 on the cylinder head 26 in a line along the direction (front-rear direction) of the axis 24 c of the crankshaft 24 so as to correspond to each cylinder. As shown in FIG. 3, each head cover 40 accommodates a valve operating mechanism including a push rod and a rocker arm for operating the intake valve and the exhaust valve. When the intake valve is open, intake air from the intake manifold 67 can be taken into the combustion chamber 110. With the exhaust valve opened, the exhaust 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 described later is disposed in the vicinity of the left side of the head cover 40. The pilot fuel injection valve 82 is viewed from one side (the left side in the present embodiment) with respect to the virtual vertical plane P1 when considering a virtual vertical plane P1 (see FIG. 7) including the axis 24c of the crankshaft 24. It is inserted into 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 as an infinitely wide plane both in the direction of the axis 24c of the crankshaft 24 and in the vertical direction, but in FIG. Only a part of the virtual vertical plane P1 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 the premixed combustion system. Provided. The gas manifold 41 is disposed 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. As shown in FIG. A gas injector 98 for injecting gas fuel is provided. The distal end portion of the gas injector 98 faces an intake branch pipe 67a formed inside the cylinder head 26 corresponding to the cylinder. By injecting 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 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 disposed so as 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 a 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 disposed in each cylinder. The main fuel injection valve 79 is disposed so as to be vertically inserted into the cylinder head 26 from above, and its upper end is disposed inside the head cover 40 and its lower end 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 path 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 the lower portion of the rail pipe 42 for supplying liquid fuel. The liquid fuel return collecting pipe 48 is arranged in parallel with the liquid fuel supply rail pipe 42 and 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 the end of the liquid fuel return collecting pipe 48.

  As shown in FIGS. 3, 7, and 9, the right side of the cylinder block 25 is located above the liquid fuel supply rail pipe 42 for the purpose of gas fuel ignition during combustion in the premixed combustion system. 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 piping 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 liquid fuel (pilot fuel) supplied from the pilot fuel supply rail piping 47 is disposed in each cylinder. The pilot fuel injection valve 82 is disposed so as to be obliquely inserted into the cylinder head 26 from above, and an upper end portion thereof is disposed at a position immediately to the left of the head cover 40, and a lower end portion thereof faces the combustion chamber 110 of the cylinder. As shown in FIG. 7, the 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.

  As shown in FIGS. 3, 7, and 9, a step is formed in the upper part of the right side surface of the engine 21 composed of the cylinder block 25 and the cylinder head 26. A rail pipe 47, a liquid fuel supply rail pipe 42, and a 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 stepped portion. The pilot fuel supply rail piping 47, the liquid fuel supply rail piping 42, and the fuel injection pump 89 are covered with a side cover 43. FIG. 9 shows a state in which a part of the side cover 43 is removed.

  As shown in FIGS. 2, 3, and 9, exhaust 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 disposed in parallel with the gas manifold 41. The outer periphery of the exhaust manifold 44 is covered with a heat shield cover 45 (however, the heat shield cover 45 is removed in FIG. 9). As shown in FIG. 3, the exhaust manifold 44 is connected to exhaust branch pipes 44a corresponding to the respective cylinders. The exhaust branch pipe 44a communicates with the combustion chamber 110 of each cylinder.

  An intake manifold 67 for distributing and supplying external air (intake air) to the combustion chamber 110 of each cylinder is arranged in parallel with 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, during combustion in the diffusion combustion system, the air supplied from the intake manifold 67 to each cylinder is compressed into the combustion chamber 110 from the main fuel injection valve 79 at an appropriate timing when the air is compressed by the slide of the piston 78. An amount of liquid fuel is 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 generated in the combustion chamber 110, and the reciprocating motion of the piston 78 passes through the rod to the crankshaft 24. Power is obtained by being converted into rotational motion.

  On the other hand, during combustion in the premixed combustion method, gas fuel from the gas manifold 41 is injected into the intake branch pipe 67a from the gas injector 98, so that the air supplied from the intake manifold 67 and the gas fuel are mixed. Is done. A small amount of pilot fuel is injected into the combustion chamber 110 from the pilot fuel injection valve 82 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. 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 through the rod to obtain power.

  Whether the combustion is performed by the diffusion combustion method or the premixed combustion method, the 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. The

  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. Yes. The fuel high-pressure pump 56 is disposed on the right side of the crankshaft 24. 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. Thereby, the rotational power from the crankshaft 24 is transmitted through 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 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 the lubricating oil cooler 58, purified by the lubricating oil strainer 59, and supplied to each part of the engine 21.

  The cooling water sent from the cooling water pump 53 shown in FIG. 4 is collected in the cylinder head cooling water piping 46 shown in FIG.

  The intercooler 51 is disposed 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 to the position between the lubricating oil cooler 58 and the lubricating oil strainer 59 along the gas manifold 41. The cooling water is supplied to the lubricating oil cooler 58.

  As shown in FIGS. 5 and 9, the cooling water pipe 46 on the cylinder head is disposed between the exhaust manifold 44 and the plurality of head covers 40 disposed above the cylinder head 26. 44 is arranged in parallel. The cooling water pipe 46 on the cylinder head is connected to a cooling water branch pipe provided corresponding to each cylinder, and a cooling water path (cooling water path formed in the cylinder head 26) of each cylinder via the 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 fuel oil is provided in the middle of the fuel path from the liquid fuel tank 33 to the fuel high-pressure pump 56.

  Further, 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. 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 disposed 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 connected to the cylinder block 25 via a plurality of clamp members 111 provided so as to protrude rightward from the front end surface of the cylinder block 25. It arrange | positions so that it may extend in an up-down direction along a 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 that controls starting and stopping of the engine 21 is provided via a stay. (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 the operator, and a display for displaying the 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 the premixed combustion method or the diffusion combustion method.

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

  As described above, the liquid fuel supply path for supplying liquid fuel to the combustion chamber 110 during combustion in the diffusion combustion system includes the liquid fuel supply main pipe 108, the liquid fuel supply rail pipe 42, and the like. . The main fuel filter is provided in the middle of the liquid fuel supply main pipe 108. The main fuel filter is disposed on the right side of the front end surface of the engine 21. The liquid fuel supply main pipe 108 extends in the vertical direction along the right side surface of the cylinder block 25 via a plurality of clamp members 111 provided so as to protrude rightward from the front end surface of the cylinder block 25. To be piped. 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 with 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 pumps 89 provided for the respective cylinders. ing. The fuel injection pump 89 is covered with a side cover 43. As shown in FIG. 3, the liquid fuel supplied to the fuel injection pump 89 is supplied to the main fuel injection valve 79 via the liquid fuel supply path 106 formed in the cylinder head 26.

  As described above, the liquid fuel supply path for supplying liquid fuel to the combustion chamber 110 during combustion in the diffusion combustion method is generally on the right side of the crankshaft 24 (a virtual vertical plane including the axis 24c of the crankshaft 24). (Right side of P1). Therefore, the operator can access the liquid fuel supply path from the right side surface of the engine 21 and perform maintenance of the liquid fuel supply main pipe 108, the liquid fuel supply rail pipe 42, the main fuel filter, and the like collectively. In particular, the right side surface of the engine 21 is a side on which the machine-side operation control device 71 is conventionally arranged, and is configured to be easily accessible for the operator.

  As described above, the pilot fuel supply path for supplying pilot fuel to the combustion chamber 110 for the purpose of igniting gas fuel at the time of combustion in the diffusion combustion system is the pilot fuel supply main pipe 107, the pilot fuel supply rail pipe 47, etc. It is configured with. A high-pressure fuel 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 fuel high-pressure 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 high-pressure fuel pump 56 and the pilot fuel filter are disposed on the right side of the front end surface of the engine 21. The pilot fuel supply main pipe 107 is arranged to extend in the vertical direction along the right side surface of the cylinder block 25 through the clamp member 111 used to support the liquid fuel supply main pipe 108. The Thus, 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 piping 47 is covered with a side cover 43 in a state of extending in the front-rear direction along the right side surface of the cylinder block 25.

  After being filtered by the pilot fuel filter, the pilot fuel fed from the high-pressure fuel pump 56 to the pilot fuel supply rail pipe 47 via the pilot fuel supply main pipe 107 is pilot provided corresponding to each cylinder. The fuel is distributed to the fuel branch pipe 109. The pilot fuel branch pipe 109 is piped so as to pass through a 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 a pilot fuel injection valve 82 provided at the distal end portion on the downstream side.

  As described above, the pilot fuel supply path for supplying pilot fuel to the combustion chamber 110 during combustion in the premixed combustion method is generally on the right side (crank of the crankshaft 24) as with the liquid fuel supply path described above. 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, it is easy for an operator to access the pilot fuel supply path from the right side surface of the engine 21 and perform maintenance of the pilot fuel supply main pipe 107, the pilot fuel supply rail pipe 47, the pilot fuel filter and the like collectively. is there. As described above, the maintenance related to the liquid fuel supply path (including the pilot fuel supply path) can be performed collectively from one side surface (in the present embodiment, the right side surface) of the engine 21, and the maintenance is easy for the operator. It has a layout.

  The pilot fuel supply main pipe 107, the pilot fuel supply rail pipe 47, and the pilot fuel branch pipe 109 all have a double pipe structure, and supply fuel oil from the fuel high-pressure pump 56 side to the pilot fuel injection valve 82. In addition, the fuel oil leaking from the pilot fuel injection valve 82 can be returned to the fuel high-pressure pump 56.

  Next, the arrangement of the pilot fuel branch pipe 109 above the cylinder head 26 will be described in more detail with reference mainly to FIGS. FIG. 10 is a perspective view showing a configuration above the cylinder head 26. FIG. 11 is a perspective view showing the configuration of the pilot fuel branch pipe support structure 120. FIG. 12 is a perspective view showing a state where the lifting jigs 95 and 95x are attached to the head bolt 99. FIG.

  As shown in FIG. 10, among the six head covers 40 arranged in a straight line, a plurality of head bolts 99 are provided in the space between adjacent head covers 40 (in this embodiment). 4 each). Of the four head bolts 99, two on the side close to the head cover 40 on one side and two on the side close to the head cover 40 on the other side each form one row. In other words, the four head bolts 99 are arranged side by side so as to form two rows between the adjacent head cover 40 and the head cover 40 in plan view. In FIG. 10 and the like, the direction (specifically, the left-right direction) in which the head bolts 99 are arranged in each row is indicated by an arrow A1. The two rows of the head bolts 99 are arranged in the same direction (specifically, the front-rear direction) as the direction in which the head cover 40 is arranged.

  Since six head covers 40 are provided in the present embodiment, five spaces between the head covers 40 are formed as shown in FIG. These five spaces are arranged in the same direction as the direction in which the head covers 40 are arranged, but the pilot fuel branch pipe support structures 120 are arranged in every other space in the arranged direction. Two pilot fuel branch pipes 109 are supported by one pilot fuel branch pipe support structure 120, and the two pilot fuel branch pipes 109 are arranged in two rows between the head covers 40. Among the bolts 99, the head bolts 99 in one row pass above the row.

  As shown in FIG. 10 and FIG. 11, a cylindrical nut 94 is attached to each head bolt 99, and the cylinder head 26 can be fastened to the cylinder block 25 by tightening the nut 94. The upper end of the head bolt 99 protrudes upward from the nut 94, and a jig 95 shown in FIG. 10 can be attached to this protruding portion. The jig 95 is used to lift the engine 21 with a crane of a hoist ship, for example, in order to install the engine 21 on the ship. A female screw hole (not shown) for screwing to the head bolt 99 is formed at the lower end of the jig 95.

  In order to ensure the balance of the engine 21 at the time of lifting, the jig 95 is, in principle, attached to each of the two head bolts 99 belonging to the same row. However, the jig 95 cannot be attached to the head bolt 99 in the row where the pilot fuel branch pipe support structure 120 (pilot fuel branch pipe 109) is arranged above the row formed by the head bolt 99. .

  As shown in FIG. 11, the pilot fuel branch pipe support structure 120 includes support nuts 122, 122, a stay mounting member 123, L-shaped stays 124, 124,. ... and the branch pipe cover 105 are mainly provided. In FIG. 11, the branch pipe cover 105 is illustrated in a perspective view with a chain line in order to easily show the pilot fuel branch pipe support structure 120.

  As shown in FIG. 11, the support nut 122 is attached by screwing into a portion protruding upward from the nut 94 in each of the head bolts 99 in the row where the pilot fuel branch pipe support structure 120 is disposed. The stay attachment member 123 includes a long and narrow horizontal plate-like portion and a support wall portion protruding upward from the plate-like portion. The horizontal plate-like portion is formed with a through hole (not shown) into which the head bolt 99 can be inserted, and is fixed to the head bolt 99 by being sandwiched between the nut 94 and the support nut 122. Is done. A branch pipe clamp member 125 is attached to the support wall portion via an L-shaped stay 124. In addition, the support wall portion and the head of the support nut 122 are connected to each other by a fixing stay, thereby realizing a strong fixation.

  The branch pipe clamp member 125 is a fixing member that supports the two pilot fuel branch pipes 109 in a state of being inserted side by side in pairs, and is fixed to the L-shaped stay 124 using bolts and nuts. In the present embodiment, three L-shaped stays 124 are attached to the stay attaching member 123. Specifically, of the three L-shaped stays 124, the branch pipe clamp member 125 that supports the pilot fuel branch pipe 109 on the most upstream side is located above the side cover 43, and the pilot fuel branch pipe 109 is moved vertically. It is arranged so that it can be inserted. A branch pipe clamp member 125 that supports the pilot fuel branch pipe 109 at a position on the left side of the space between the head cover 40 and the head cover 40 is disposed so that the pilot fuel branch pipe 109 can be inserted in the left-right direction. A branch pipe clamp member 125 that supports the pilot fuel branch pipe 109 at a position on the right side of the space between the head cover 40 and the head cover 40 is disposed so that the pilot fuel branch pipe 109 can be inserted in the left-right direction.

  By inserting the pilot fuel branch pipes 109 into the three branch pipe clamp members 125 and piping them, two pilot fuel branch pipes 109 can be arranged together in the space between the head cover 40 and the head cover 40.

  A branch pipe cover 105 is attached to the support wall portion of the stay attachment member 123. The branch pipe cover 105 has a width corresponding to the width of one row of the head bolts 99 described above. Further, the branch pipe cover 105 has an inverted U-shaped cross-sectional shape, and is arranged so as to cover the upper and both sides of the two pilot fuel branch pipes 109 extending along the row of head bolts 99. As described above, the pilot fuel branch pipe 109 piped together above the cylinder head 26 is covered with the branch pipe cover 105, so that even if fuel leaks from the pilot fuel branch pipe 109, it is scattered around. Can be prevented, and maintainability and safety are improved.

  With the above configuration, as shown in FIG. 7, the pilot fuel branch pipes 109 substantially form one set and extend upward from the pilot fuel supply rail piping 47 inside the side cover 43. As shown in FIG. 5, the two cutouts 43a formed in the side cover 43 pass through each. The two pilot fuel branch pipes 109 that protrude above the side cover 43 slightly extend forward in the front-rear direction, and then extend upward again, and are supported by the pilot fuel branch pipe support structure 120 and are spaced between the head covers 40. It passes through (the space above the head bolt 99) from right to left. Thereafter, one of the two pilot fuel branch pipes 109 is bent so as to go around the head cover 40 on one side from the left side, and the other one is bent so as to go around the head cover 40 on the other side from the left side. Each pilot fuel branch pipe 109 passes through a space between the head cover 40 and the cylinder head cooling water pipe 46 and is connected to a pilot fuel injection valve 82 installed in the vicinity of each head cover 40.

  In the present embodiment, the gap between the nut 94 attached to the head bolt 99 in one row and the nut 94 in the next row is small, and the gap between the nut 94 and the adjacent head cover 40 is also small. Therefore, the pilot fuel branch pipe 109 cannot pass beside the nut 94. In this regard, in the present embodiment, the pilot fuel branch pipe 109 is configured to pass right and left above the head bolt 99, so that the pilot structure can be reduced in size in plan view while the periphery of the head cover 40 is realized. Space for the fuel branch pipe 109 can be secured.

  As described above, the jig 95 for lifting cannot be attached to the head bolt 99 in the row where the pilot fuel branch pipe support structure 120 is disposed, but the jig is not attached to the head bolt 99 in the other rows. 95 can be attached. In this regard, in this embodiment, the two pilot fuel branch pipes 109 pass above the head bolts 99 for one row of the head bolts 99 arranged in two rows in the space between the adjacent head covers 40. Is arranged. In addition, since the two pilot fuel branch pipes 109 pass together in a certain space as described above, the pilot fuel branch pipe 109 does not pass over any of the two rows of head bolts 99 in the adjacent space. . Accordingly, the number of rows of head bolts 99 through which the pilot fuel branch pipes 109 do not pass can be increased, so that the degree of freedom of layout for mounting the lifting jig 95 can be increased.

  In addition, the structure of the jig | tool 95 for lifting is not limited to what is shown in FIG. For example, as shown in FIG. 12, in addition to the jig 95 described above, a jig 95x having another shape may be mounted on the head bolt 99.

  As described above, the engine 21 of the present embodiment has a premixed combustion method in which gaseous fuel is mixed with air and then flows into the combustion chamber 110, and diffusion in which liquid fuel is injected into the combustion chamber 110 for combustion. It is possible to cope with the combustion method. The engine 21 includes a head cover 40, a pilot fuel injection valve 82, a pilot fuel supply rail pipe 47, a plurality of head bolts 99, and a pilot fuel branch pipe 109. The head cover 40 is provided for each cylinder so as to cover the valve mechanism of the engine 21, and a plurality of head covers 40 are arranged in the axial direction of the crankshaft 24 of the engine 21. The pilot fuel injection valve 82 is arranged for each cylinder so as to extend obliquely downward from one side to the combustion chamber 110 from the virtual vertical plane P1 including the axis 24c of the crankshaft 24, and combustion in the premixed combustion system Sometimes pilot fuel is supplied to the combustion chamber 110 for the purpose of gas fuel ignition. The pilot fuel supply rail piping 47 is disposed on the opposite side to the one side with respect to the virtual vertical plane P1, and is commonly used by a plurality of cylinders for supplying pilot fuel to the pilot fuel injection valve 82. As shown in FIG. 10, the head bolts 99 are arranged so as to form two rows arranged in the same direction as the direction in which the head covers 40 are arranged between the adjacent head covers 40 in a plan view. The head 26 and the cylinder block 25 are fixed. The pilot fuel branch pipe 109 branches from the pilot fuel supply rail pipe 47 and passes over the head bolts 99 in only one of the two rows between the adjacent head covers 40, and the pilot fuel injection valve 82.

  Thereby, the pilot fuel branch pipe 109 can be rationally arranged by utilizing the space between the adjacent head covers 40. Further, since the lifting jigs 95 and 95x can be easily mounted on the head bolts 99 in the row where the pilot fuel branch pipe 109 does not pass above, the head bolts 99 are installed via the head bolt 99 for the installation of the engine 21 and the like. It is easy to lift the engine 21.

  Further, in the engine 21 of the present embodiment, spaces are formed between the head covers 40 adjacent to each other among the plurality of head covers 40. As shown in FIG. 10, the space through which the pilot fuel branch pipe 109 passes and the space through which the pilot fuel branch pipe 109 does not pass are alternately arranged in the direction in which the head cover 40 is arranged.

  As a result, the degree of detouring of the pilot fuel branch pipe 109 can be reduced, so that the length can be shortened.

  Further, in the engine 21 of the present embodiment, as shown in FIG. 11, the two pilot fuel branch pipes 109 are disposed above the head bolts 99 in one row.

  Thereby, since the row | line | column of the head bolt 99 which can mount | wear with the lifting jig | tool 95,95x can be increased, the lifting of the engine 21 becomes still easier. Further, by supporting the two pilot fuel branch pipes 109 with a common member (branch pipe clamp member 125), the configuration can be simplified and made compact.

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

  In the above-described embodiment, the engine 21 is used as a drive source for a ship propulsion and power generation mechanism, but is not limited thereto, and may be a drive source used for other purposes.

  The rows formed by the head bolts 99 in the space between the adjacent head covers 40 may be three or more rows instead of the two rows.

  In the above embodiment, two pilot fuel branch pipes 109 are arranged together between adjacent head covers 40. However, the present invention is not limited to this. For example, three pilot fuel branch pipes 109 are arranged together. It is good also as what is piped.

  In the above embodiment, the liquid fuel supply rail pipe 42 and the pilot fuel supply rail pipe 47 are arranged on the same side with respect to the crankshaft 24. However, the present invention is not limited to this. Instead of this, the liquid fuel supply rail pipe 42 may be arranged on one side with respect to the crankshaft 24, and the pilot fuel supply rail pipe 47 may be arranged on the other side with respect to the crankshaft 24.

21 engine (multi-cylinder engine)
24 crankshaft 42 liquid fuel supply rail piping 43 side cover 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 99 head bolt (lifting member)
105 Branch pipe cover 110 Combustion chamber 120 Pilot fuel branch pipe support structure

Claims (3)

In a multi-cylinder engine compatible with a premixed combustion method in which gaseous fuel is mixed with air and then flows into the combustion chamber, and a diffusion combustion method in which liquid fuel is injected into the combustion chamber and combusted,
A head cover provided for each cylinder to cover the valve operating mechanism of the multi-cylinder engine, and a plurality of head covers arranged side by side in the axial direction of the crankshaft of the multi-cylinder engine;
Each cylinder is arranged so as to extend obliquely downward from one side of the virtual vertical plane including the axis of the crankshaft toward the combustion chamber for the purpose of gas fuel ignition during combustion in the premixed combustion method. A pilot fuel injection valve for supplying pilot fuel to the combustion chamber;
A pilot fuel supply rail pipe that is disposed on the opposite side to the one side with respect to the virtual vertical plane and is commonly used in the plurality of cylinders for supplying pilot fuel to the pilot fuel injection valve;
A plurality of heads arranged between the adjacent head covers in a plan view so as to form a plurality of rows arranged in the same direction as the head covers are arranged, and fixing the cylinder head and the cylinder block of the multi-cylinder engine. Bolts,
A pilot fuel branched from the pilot fuel supply rail piping and passing over the head bolts in only a part of the plurality of rows between the adjacent head covers and connected to the pilot fuel injection valve A branch pipe,
A multi-cylinder engine comprising: The multi-cylinder engine according to claim 1,
A space is formed between the head covers adjacent to each other among the plurality of head covers,
The multi-cylinder engine, wherein the space through which the pilot fuel branch pipe passes and the space through which the pilot fuel branch pipe does not pass are alternately arranged in a direction in which the head covers are arranged. The multi-cylinder engine according to claim 1 or 2,
A multi-cylinder engine, wherein a plurality of pilot fuel branch pipes pass above the head bolts in one row.

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