JP6539703B2 - Marine diesel engine - Google Patents

Description

  The present invention relates to a marine diesel engine mounted on a ship.

  Conventionally, in the field of ships, a marine diesel engine to which a plurality of superchargers such as a two-stage supercharger are applied is known as a means for improving the output of the engine body and the fuel efficiency. For example, Patent Document 1 discloses that a turbocharger (turbocharger), in which a compressor is configured to be rotatable with a turbine by pressure of exhaust gas discharged from an engine body, is compressed in two stages with a combustion gas such as air. A two-stage turbocharged diesel engine is disclosed which is provided as a high pressure and low pressure turbocharger for feeding to the engine body. In these turbochargers, each turbine is connected in series with the engine body through exhaust gas exhaust piping. Each compressor is connected in series with the engine body via a pipe for feeding a combustion gas. Further, in the diesel engine disclosed in Patent Document 1, an auxiliary blower of a motor drive system is interposed in the middle of the delivery pipe as a means for replenishing the necessary amount of combustion gas to the engine body. There is. Furthermore, a switching valve capable of switching the opening and closing of a line leading to the auxiliary blower is provided between the auxiliary blower and the delivery pipe.

  In general, the auxiliary blower has a low load on the engine body of a marine diesel engine (hereinafter referred to as an engine load) at the start of the engine body, and the pressure of exhaust gas from the engine body is therefore a driving source of the turbocharger. Activate when insufficient. In this case, the auxiliary blower compresses and sucks the combustion gas via the feed pipe, and supplies the compressed combustion gas to the engine body.

Japanese Patent Publication No. 63-49053

  However, in the prior art described in Patent Document 1, the flow path for the combustion gas to pass through the low-pressure stage compressor and the high-pressure stage compressor in this order to the engine body, and the combustion gas as the auxiliary blower. In order to form in combination with the flow path leading up to the engine body, the pipe is provided with a switching valve to switch the flow path of the combustion gas, so the pipe structure becomes large and complicated. There are times when Further, in the prior art described in Patent Document 1, it is necessary to switch the opening and closing of the pipeline leading to the auxiliary blower with the switching valve according to the state of operation or stop of the auxiliary blower. Opening and closing control must be performed.

  This invention is made in view of said situation, Comprising: It aims at providing the marine diesel engine which can combine a several supercharger and an auxiliary | assistant blower by simple structure.

  In order to solve the problems described above and achieve the object, the marine diesel engine according to the present invention uses an engine body that burns fuel to generate propulsion of a ship, and exhaust gas discharged from the engine body. A first supercharger that sucks and compresses combustion gas from the outside by rotating the compressor, and the first supercharger by rotating the compressor using the exhaust gas A second supercharger that further compresses the compressed combustion gas and feeds it to the engine body, and a compressor of the first supercharger to a compressor of the second supercharger for combustion It is characterized by comprising: a flow pipe for flowing gas; and an auxiliary blower provided in the flow pipe and assisting the supply of the compressed combustion gas to the engine body.

  In the marine diesel engine according to the present invention, in the above-mentioned invention, the check valve for preventing the backflow of the combustion gas from the second turbocharger side to the first turbocharger side in the flow pipe. And the flow pipe is bifurcated between the compressor of the first turbocharger and the check valve, and between the check valve and the compressor of the second turbocharger. Of the two branched flow pipes, the first branch pipe is provided with the auxiliary blower, and the second branch pipe is provided with the check valve.

  In the marine diesel engine according to the present invention, in the above-mentioned invention, the cooler is disposed between the compressor of the first turbocharger and the check valve, and cools the combustion gas in the flow pipe. And the like.

  In the marine diesel engine according to the present invention, in the above invention, a pressure detection unit for detecting the pressure of the combustion gas supplied to the engine body, and a detected pressure value is less than a predetermined threshold value. A control unit configured to operate the auxiliary blower and to stop the operation of the auxiliary blower when the detected pressure value is equal to or more than the threshold value.

  ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to combine the several supercharger and auxiliary blower in a marine diesel engine by simple structure.

FIG. 1 is a schematic view showing an engine body of a marine diesel engine according to an embodiment of the present invention. FIG. 2 is a schematic view showing an example of the configuration of a marine diesel engine according to an embodiment of the present invention.

  Hereinafter, preferred embodiments of a marine diesel engine according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited by the present embodiment. In addition, it should be noted that the drawings are schematic, and dimensional relationships among elements, ratios of elements, and the like may differ from actual ones. Even between the drawings, there may be a case where the dimensional relationships and ratios differ from one another. Further, in the drawings, the same components are denoted by the same reference numerals.

(Composition of marine diesel engine)
In the following, first, a schematic configuration of an engine body of a marine diesel engine according to an embodiment of the present invention will be described, and then an overall configuration of the marine diesel engine will be described.

  FIG. 1 is a schematic view showing an engine body of a marine diesel engine according to an embodiment of the present invention. As shown in FIG. 1, the engine main body 1 includes a base plate 71 located below, a frame 72 provided on the base plate 71, and a cylinder jacket 73 provided on the frame 72. The base plate 71, the frame 72 and the cylinder jacket 73 are integrally fastened and fixed by a plurality of tie bolts (connection members) 74 and nuts 75 extending in the vertical direction.

  The cylinder liner 76 is disposed in the cylinder jacket 73, and the cylinder cover 77 is fixed at the upper portion to define a space, in which the piston 78 is provided so as to be capable of reciprocating up and down. Further, the cylinder cover 77 is provided with an exhaust valve 79. The exhaust valve 79 can be opened and closed by the valve operating device 80. The exhaust valve 79 forms a cylinder (combustion chamber) 2 together with the cylinder liner 76, the cylinder cover 77 and the piston 78. The exhaust valve 79 opens and closes the cylinder 2 and the exhaust port 25.

  Fuel (for example, low-quality oil, natural gas, or a mixed fuel thereof) is supplied from such a fuel injection pump (not shown) to such a cylinder 2 and combustion gas (compressed by a compressor (not shown) For example, air, recycle gas, or a mixture thereof is supplied. Thus, in the cylinder 2, the supplied fuel and the combustion gas are burned. Then, the piston 78 reciprocates in the axial direction of the piston by the energy generated by this combustion. At this time, when the exhaust valve 79 is operated by the valve gear 80 and the cylinder 2 is opened, the exhaust gas generated by the combustion is pushed out to the exhaust port 25 while the combustion gas from the scavenging port (not shown) Introduced in 2.

  The upper end of the piston rod 81 is connected to the lower end of the piston 78. The base plate 71 constitutes a crankcase, and a crankshaft 82 is rotatably supported by a bearing 83. The lower end portion of the connecting rod 85 is rotatably connected to the crankshaft 82 via a crank 84. The frames 72 are arranged such that guide plates 86 provided along the piston axial direction form a pair at intervals in the width direction. The crosshead 87 includes a crosshead pin 88 connected to the lower end of the piston rod 81 and a crosshead bearing (not shown) connected to the upper end of the connecting rod 85 connected to the crankshaft 82. In the lower half of 88, they are pivotally connected. The cross head 87 is disposed between the pair of guide plates 86 and is movably supported along the pair of guide plates 86.

  Therefore, when the piston 78 reciprocates along the piston axial direction, the piston rod 81 reciprocates along with the piston 78 along the piston axial direction, whereby the cross head 87 along the piston axial direction along the guide plate 86 Reciprocate. Thereby, the crosshead pin 88 of the crosshead 87 applies rotational driving force to the connecting rod 85 via the crosshead bearing. The rotational driving force causes the crank 84 connected to the lower end portion of the connecting rod 85 to perform a crank movement to rotate the crankshaft 82.

  Below, the whole structure of the marine diesel engine which concerns on embodiment of this invention is demonstrated. FIG. 2 is a schematic view showing an example of the configuration of a marine diesel engine according to an embodiment of the present invention. As shown in FIG. 2, the marine diesel engine 10 according to the present embodiment includes the engine body 1, an injection unit 5 for supplying fuel to the engine body 1, and the pressure of the combustion gas supplied to the engine body 1. And a pressure detection unit 8 for detection. The marine diesel engine 10 further includes a two-stage turbocharger 11, a cooler 15 for cooling the compressed combustion gas, an auxiliary blower 16, a check valve 17, and a control unit 18. . Further, as shown in FIG. 2, the marine diesel engine 10 includes air supply lines G1, G4, G11 as pipes for air supply, and exhaust lines G2, G3, G12 as pipes for exhaust. Among these pipes, the air supply line G11 and the exhaust line G12 are pipes of the two-stage supercharger 11. In FIG. 2, solid arrows indicate gas flow and piping. An alternate long and short dash line indicates an electrical signal line.

  Although not shown, the engine body 1 is a propulsion engine (main engine) that drives and rotates a propeller for propulsion of a ship through a propeller shaft. The engine body 1 is a two-stroke diesel engine such as a uniflow swept exhaust crosshead diesel engine. For example, as shown in FIG. 2, the engine body 1 includes a plurality of (six in the present embodiment) cylinders 2, a scavenging trunk 3, and an exhaust manifold 4. Although not shown in FIG. 2, the engine body 1 reciprocates (up and down) along the interiors of the cylinders 2 (see the piston 78 shown in FIG. 1) and the propeller shaft along with the reciprocation of the pistons. (See FIG. 1, the crank 84 shown in FIG. 1), a crankshaft (see the crankshaft 82 shown in FIG. 1), a crosshead (see the crosshead 87 shown in FIG. 1), and the like.

  Each of the plurality of cylinders 2 forms a combustion chamber in which intake and exhaust for reciprocating the piston and fuel combustion and the like are performed. The scavenging air trunk 3 is in communication with the combustion chamber in each cylinder 2 via a scavenging air port (not shown) in the engine body 1. The exhaust manifold 4 communicates with the combustion chamber in each cylinder 2 via an exhaust passage (not shown) in the engine body 1. The engine body 1 reciprocates the piston by burning fuel in the combustion chamber in each cylinder 2 and converts this reciprocation motion to rotational motion of a rotating shaft such as a propeller shaft or a crankshaft, thereby Generate a driving force. At this time, the engine body 1 makes the flow of the intake and exhaust in each cylinder 2 one direction from the lower side to the upper side so as to eliminate the remaining of the exhaust gas. Specifically, the combustion gas is supplied from the scavenging air trunk 3 to the combustion chamber in each cylinder 2, and the exhaust gas after combustion is discharged from the combustion chamber in each cylinder 2 to the exhaust manifold 4.

  The air supply line G1 is a flow pipe for supplying combustion gas to the engine body 1 from the two-stage supercharger 11 side or the auxiliary blower 16 side toward the engine body 1 and supplying the combustion gas to the engine body 1 is there. As shown in FIG. 2, the air supply line G <b> 1 is connected to the scavenging air trunk 3 of the engine body 1. The exhaust line G2 is a flow pipe for circulating the exhaust gas from the engine body 1 to the outside. As shown in FIG. 2, the exhaust line G2 is connected to the exhaust manifold 4 of the engine body 1. The exhaust gas is a gas discharged from the engine body 1 to the outside through the exhaust line G2 and the like.

  The injection unit 5 injects fuel into the combustion chamber in each cylinder 2. As shown in FIG. 2, the injection unit 5 includes a plurality of fuel injection pumps 6 and a plurality of fuel injection valves 7, and is provided in the engine body 1. In the present embodiment, six fuel injection pumps 6 are provided in the engine body 1 corresponding to the number of cylinders 2 described above. For example, as shown in FIG. 2, two fuel injection valves 7 are provided in each cylinder 2 in such a manner that the injection ports are directed in different directions in the combustion chamber.

  Each of the plurality of fuel injection pumps 6 feeds fuel to each fuel injection valve 7 via a pipe for fuel. The injection unit 5 injects the fuel from each fuel injection valve 7 to the combustion chamber in each cylinder 2 by the pumping action of the fuel by each fuel injection pump 6. The injection amount and injection timing of the fuel by the injection unit 5 are controlled respectively through the drive control of each fuel injection pump 6 by the control unit 18 and the open / close control of each fuel injection valve 7.

  The pressure detection unit 8 detects the pressure of the combustion gas supplied to the engine body 1. For example, as shown in FIG. 2, the pressure detection unit 8 is provided in the scavenging trunk 3 of the engine body 1. The pressure detection unit 8 charges the internal pressure of the scavenging air trunk 3 for receiving the combustion gas through the air supply line G1 to the engine body 1 (specifically, the two-stage supercharger 11 or the auxiliary blower) 16 is detected as the pressure of the combustion gas (compressed gas). The pressure detection unit 8 transmits an electric signal indicating the detected pressure to the control unit 18 each time the pressure of the combustion gas is detected.

  The two-stage type supercharger 11 is an example of a multi-stage type supercharger capable of compressing combustion gas such as air stepwise and using the exhaust gas from the engine body 1 to the engine body 1 . In the present embodiment, as shown in FIG. 2, the two-stage supercharger 11 includes the low pressure supercharger 12, the high pressure supercharger 13, the intercooler 14, the air supply line G 11, and the exhaust. And a line G12. For example, the two-stage supercharger 11 is provided between the air supply line G1 and the exhaust line G2 for performing intake and exhaust to the engine body 1, and the air supply line G4 and the exhaust line G3 for performing intake and exhaust to the outside. ing.

  The low pressure supercharger 12 is a first supercharger (turbocharger) that performs the first-stage compression of the combustion gas in the two-stage supercharger 11. In the present embodiment, as shown in FIG. 2, the low pressure supercharger 12 includes a low pressure compressor 12a, a low pressure turbine 12b, and a rotating shaft 12c, and includes a charge line G4 and an exhaust line G3 and a high pressure. It is provided between the stage turbocharger 13. The low-pressure stage compressor 12a and the low-pressure stage turbine 12b are respectively constituted by an impeller or the like, and are connected to each other by a rotating shaft 12c so as to integrally rotate around the rotating shaft 12c. The low pressure stage turbocharger 12 rotates the low pressure stage compressor 12 a together with the low pressure stage turbine 12 b using the exhaust gas discharged from the engine body 1. Thereby, the low pressure stage turbocharger 12 sucks in and compresses the combustion gas from the outside.

  Further, as shown in FIG. 2, on the gas inlet side of the low-pressure stage compressor 12a, an air supply for sucking in a gas such as new air (also referred to as fresh air) from the outside (atmosphere) as a combustion gas. Line G4 is connected. Although not particularly illustrated, the inlet end (air suction port) of the air supply line G4 is provided with a filter for preventing foreign matter from being sucked into the air supply line G4, and noise when suctioning air from the outside is reduced. And a silencer for the An air supply line G11 communicating with the high pressure stage turbocharger 13 or the like is connected to the gas output side of the low pressure stage compressor 12a. An exhaust line G12 communicating with the high pressure stage turbocharger 13 or the like is connected to the gas inlet side of the low pressure stage turbine 12b. An exhaust line G3 leading to a chimney (not shown) or the like for exhausting the exhaust gas to the outside is connected to the gas outlet side of the low pressure stage turbine 12b.

  The high pressure stage supercharger 13 is a second supercharger (turbocharger) that performs the second stage compression of the combustion gas in the two-stage supercharger 11. In the present embodiment, as shown in FIG. 2, the high-pressure stage turbocharger 13 includes a high-pressure stage compressor 13a, a high-pressure stage turbine 13b, and a rotating shaft 13c, and includes an air supply line G1, an exhaust line G2, and a low pressure. It is provided between the stage turbocharger 12. The high-pressure stage compressor 13a and the high-pressure stage turbine 13b are respectively configured by an impeller or the like, and are connected to each other by a rotating shaft 13c so as to integrally rotate around the rotating shaft 13c. The high pressure stage turbocharger 13 rotates the high pressure stage compressor 13 a together with the high pressure stage turbine 13 b using the exhaust gas discharged from the engine body 1. As a result, the high pressure supercharger 13 further compresses the combustion gas compressed by the low pressure supercharger 12 described above and feeds it to the engine body 1.

  Further, as shown in FIG. 2, an air supply line G11 communicating with the low pressure compressor 12a is connected to the gas inlet side of the high pressure compressor 13a. An air supply line G1 communicating with the scavenging air trunk 3 of the engine body 1 is connected to the gas outlet side of the high-pressure stage compressor 13a. An exhaust line G2 communicating with the exhaust manifold 4 of the engine body 1 is connected to the gas inlet side of the high pressure stage turbine 13b. An exhaust line G12 communicating with the low pressure stage turbine 12b is connected to the gas outlet side of the high pressure stage turbine 13b.

  The intercooler 14 is a cooler for cooling the combustion gas in the air supply line G11. In the present embodiment, the intercooler 14 is disposed in the middle of the air supply line G11. More specifically, as shown in FIG. 2, the intercooler 14 is disposed between the compressor (low-pressure stage compressor 12 a) of the low-pressure stage turbocharger 12 and the check valve 17. When the low pressure supercharger 12 is in operation, the intercooler 14 heats the high temperature combustion gas flowing in the air supply line G11 after being compressed by the low pressure compressor 12a, for example, heat with cooling water. Cool by replacement etc.

  The air supply line G11 is a flow pipe for circulating the combustion gas from the compressor (low-pressure stage compressor 12a) of the low-pressure stage turbocharger 12 to the compressor (high-pressure stage compressor 13a) of the high-pressure stage turbocharger 13. . As shown in FIG. 2, one end of the air supply line G11 is connected to the low pressure stage compressor 12a, and the other end is connected to the high pressure stage compressor 13a. In the present embodiment, the air supply line G11 bifurcates between the low pressure stage compressor 12a and the check valve 17, and joins between the check valve 17 and the high pressure stage compressor 13a. Specifically, as shown in FIG. 2, the air supply line G11 is a flow pipe including two branch pipes of a bypass line G13 and an air supply line G14. The bypass line G13 and the air supply line G14 branch between the gas outlet side of the intercooler 14 and the gas inlet side of the check valve 17 in the middle of the air supply line G11, and the gas of the check valve 17 It joins with each other between the outlet side and the gas inlet side of the high-pressure stage compressor 13a. In the present embodiment, as shown in FIG. 2, the bypass line G13 bypasses the check valve 17 and forms a bypass flow passage passing through the auxiliary blower 16.

  The exhaust line G12 is a flow pipe that circulates the exhaust gas from the turbine of the high pressure stage turbocharger 13 (high pressure stage turbine 13b) to the turbine of the low pressure stage turbocharger 12 (low pressure stage turbine 12b). As shown in FIG. 2, one end of the exhaust line G12 is connected to the high pressure stage turbine 13b and the other end is connected to the low pressure stage turbine 12b.

  The cooler 15 cools the compressed combustion gas. In the present embodiment, the cooler 15 is provided in the middle of the air supply line G1, as shown in FIG. The cooler 15 is for high temperature combustion flowing in the air supply line G1 after being compressed in two stages by the low pressure compressor 12a and the high pressure compressor 13a when the two-stage supercharger 11 is in operation. The gas is cooled, for example by heat exchange with cooling water.

  The auxiliary blower 16 assists the delivery of the compressed combustion gas to the engine body 1. In the present embodiment, the auxiliary blower 16 is constituted of, for example, an impeller and a motor for rotationally driving the same, and is connected to the air supply line G11 which is a flow pipe between the low pressure compressor 12a and the high pressure compressor 13a. Provided. Specifically, as shown in FIG. 2, the auxiliary blower 16 is provided on the pipeline of the bypass line G13 (first branch pipe) of the air supply line G11 branched into two. At this time, the auxiliary blower 16 is disposed so as to be able to pressure-feed the combustion gas from the branch portion side of the bypass line G13 and the air supply line G14 toward the junction portion side of the bypass line G13 and the air supply line G14. .

  Such an auxiliary blower 16 operates, for example, for a period during which the scavenging trunk 3 of the engine body 1 needs to be replenished with the compressed combustion gas. The auxiliary blower 16 sucks air (fresh air) from the outside through the air supply lines G4, G11, the low pressure stage compressor 12a, etc., and compresses the sucked air as a combustion gas during the operation period. Send to the scavenging trunk 3 side. As a period during which the auxiliary blower 16 operates, for example, the engine main body 1 is operated at a low load immediately after the start of the engine main body 1 and the operation of the two-stage supercharger 11 is insufficient. For example, a period in which the operation of the feeder 11 is insufficient may be mentioned.

  The check valve 17 prevents backflow of the combustion gas from the high pressure stage turbocharger 13 side to the low pressure stage turbocharger 12 side in the air supply line G11. In the present embodiment, as shown in FIG. 2, the check valve 17 is provided on the pipeline of the air supply line G <b> 14 (second branch pipe) of the air supply line G <b> 11 branched into two. Under the present circumstances, the non-return valve 17 is arrange | positioned so that the distribution direction of the gas for combustion in the air supply line G14 can be restrict | limited to one direction which goes to the high pressure stage compressor 13a side from the low pressure stage compressor 12a side. As such a check valve 17, for example, a butterfly valve or the like is suitably used.

  The control unit 18 has an engine control function of controlling the operation of the engine body 1 and an auxiliary blower control function of controlling the operation of the auxiliary blower 16. The control unit 18 includes a CPU, a memory, and the like that execute various programs to perform data processing, and each fuel injection pump 6 of the injection unit 5 and the fuel injection pump 6 are shown as indicated by a dashed line (electrical signal line) in FIG. , And controls the auxiliary blower 16. Further, the control unit 18 can control the respective fuel injection valves 7 of the injection unit 5 although an electric signal line is not particularly illustrated.

  In the present embodiment, the control unit 18 controls the operation of the engine main body 1 based on various information such as the traveling speed of the ship designated by the operation unit (not shown) so as to be switchable and the required load. Specifically, the control unit 18 controls the injection amount and injection timing of the fuel with respect to the combustion chamber in each cylinder 2 through the drive control of each fuel injection pump 6 and each fuel injection valve 7. Thereby, the control unit 18 controls the number of revolutions of the engine main body 1, fuel combustion, and the like, and controls the output of the engine main body 1 so that the ship travels or stops at the designated navigation speed.

  Further, the control unit 18 controls the operation of the auxiliary blower 16 in accordance with the operation status of the two-stage supercharger 11. In the present embodiment, the control unit 18 operates in a period from when the engine body 1 starts to when the two-stage supercharger 11 starts to operate stably, or when the engine body 1 is operated at a low load, resulting in a two-stage excess. The auxiliary blower 16 is operated while the feeder 11 is in an insufficient operating condition. Specifically, the control unit 18 receives the electrical signal from the pressure detection unit 8 and acquires the detection value of the pressure of the combustion gas by the pressure detection unit 8 based on the received electrical signal. The control unit 18 activates the auxiliary blower 16 when the detected pressure value is less than a predetermined threshold. On the other hand, the control unit 18 stops the operation of the auxiliary blower 16 when the detected pressure value is equal to or more than a predetermined threshold value. Here, the pressure of the combustion gas detected by the pressure detection unit 8 is the pressure of the combustion gas (compressed combustion gas) supplied into the scavenging trunk 3 of the engine body 1. The predetermined threshold value is set to, for example, a value equal to or higher than the pressure of the combustion gas in the scavenging trunk 3 when the two-stage supercharger 11 starts to operate stably. The stable operation of the two-stage turbocharger 11 means that both the low pressure turbocharger 12 and the high pressure turbocharger 13 are operating stably, that is, the low pressure turbocharger 12 and the high pressure This means that the combustion gas compressed in two stages by the action of the stage turbocharger 13 can be stably supplied to the engine body 1 in the necessary amount.

(Operation of gas for combustion)
Next, with reference to FIG. 2, the operation of feeding the combustion gas to the engine body 1 in the marine diesel engine 10 according to the embodiment of the present invention will be described. In the marine diesel engine 10, the exhaust gas discharged from the engine body 1 is a gas with a low pressure during startup of the engine body 1 or during low load operation (operation when the engine load is less than a predetermined value); It does not have enough energy to operate the stage type turbocharger 11 stably. That is, in such a situation, the two-stage turbocharger 11 is in an insufficient operating state.

  While the two-stage supercharger 11 is in an insufficient operating condition, the amount of supplied combustion gas in the scavenging air trunk 3 tends to be insufficient compared to the amount required by the engine body 1. In this state, the control unit 18 determines that the detection value of the pressure of the combustion gas by the pressure detection unit 8 is less than a predetermined threshold, and operates the auxiliary blower 16. The auxiliary blower 16 operates by motor drive based on this control, and pumps the combustion gas to the engine body 1.

  Specifically, the auxiliary blower 16 sucks air (fresh air) as a combustion gas from the outside via the air supply lines G4, G11 and the low pressure stage compressor 12a. At this time, the combustion gas flows into the air supply line G4 from the outside through the filter and silencer (not shown) at the air intake. Next, the combustion gas flows from the air supply line G4 through the low pressure stage compressor 12a into the air supply line G11, and is cooled by the intercooler 14 if necessary, and then the air supply line G11 to the bypass line It flows into G13. The auxiliary blower 16 sucks in and compresses the combustion gas flowing into the bypass line G13, and pumps the combustion gas pressurized by the compression action to the side of the engine main body 1. The high pressure combustion gas thus pumped is supplied from the auxiliary blower 16 through the bypass line G13 to a midway portion between the high-pressure stage compressor 13a and the check valve 17 in the air supply line G11, for example, the air supply line G14. It flows into the outlet portion or in the vicinity thereof, and flows into the high pressure stage compressor 13a through the air supply line G11. At the same time, the high pressure combustion gas applies pressure to the check valve 17 from the gas outlet side through the air supply line G14.

  Here, the pressurizing force of the high-pressure combustion gas to the gas outlet side of the check valve 17 flows from the outside into the gas inlet side of the check valve 17 through the low-pressure stage compressor 12a and the air supply lines G11 and G14. Higher than the pressure of the air (combustion gas before being compressed by the auxiliary blower 16). Therefore, the check valve 17 is automatically closed by the pressure. Thereby, the check valve 17 prevents the backflow of the combustion gas in the air supply line G14 (the gas flow from the high pressure stage compressor 13a side to the low pressure stage compressor 12a side), and also in the air supply line G14. Block the flow of air from the outside that has partially flowed.

  As described above, in the state where the check valve 17 is closed, the auxiliary blower 16 continuously performs the above-described pumping of the combustion gas based on the control by the control unit 18. The high pressure combustion gas pressurized (boosted) by the auxiliary blower 16 flows into the high pressure stage compressor 13a through the bypass line G13 and the air supply line G11, passes through the high pressure stage compressor 13a, and is supplied. It flows into the air line G1. Next, the high-pressure combustion gas is cooled by the cooler 15 while flowing in the air supply line G1, and is then supplied to the scavenging trunk 3 of the engine body 1. By continuously supplying the combustion gas to the scavenging trunk 3, the amount of combustion gas supplied in the scavenging trunk 3 sequentially increases. In this way, the auxiliary blower 16 can increase the amount of combustion gas supplied in the scavenging trunk 3 to the amount required by the engine body 1.

  On the other hand, when the engine load increases with the operation of the engine body 1, the amount of exhaust gas discharged from the engine body 1 and the pressure increase accordingly. In this case, the exhaust gas discharged from the exhaust manifold 4 of the engine body 1 flows into the high pressure turbine 13b through the exhaust line G2. The high pressure turbine 13b discharges the exhaust gas used for the rotation to the exhaust line G12 while rotating by the pressure of the exhaust gas from the exhaust line G2. The exhaust gas discharged to the exhaust line G12 flows into the low pressure turbine 12b through the exhaust line G12. The low pressure turbine 12b discharges the exhaust gas used for the rotation to the exhaust line G3 while rotating by the pressure of the exhaust gas from the exhaust line G12. The exhaust gas from the low pressure stage turbine 12b is exhausted from the chimney (not shown) to the outside through, for example, an exhaust line G3.

  The rotation of the high-pressure stage turbine 13b due to the pressure of the exhaust gas described above is transmitted to the high-pressure stage compressor 13a via the rotation shaft 13c. Thereby, the high pressure stage compressor 13a rotates with the rotation of the high pressure stage turbine 13b. Similarly, the rotation of the low pressure turbine 12b due to the pressure of the exhaust gas is transmitted to the low pressure compressor 12a via the rotating shaft 12c. Thus, the low pressure compressor 12a rotates with the rotation of the low pressure turbine 12b. Thus, the low pressure supercharger 12 and the high pressure supercharger 13 of the two-stage supercharger 11 operate to perform two-stage supercharging of the combustion gas to the engine body 1.

  As the engine load increases, the pressure of the combustion gas in the scavenging trunk 3 increases, but does not reach the predetermined threshold yet. In this state, the control unit 18 determines that the detection value of the pressure of the combustion gas by the pressure detection unit 8 is less than a predetermined threshold, and continues the operation of the auxiliary blower 16. The auxiliary blower 16 continues to pump the combustion gas to the engine body 1 based on the control by the control unit 18.

  Specifically, the auxiliary blower 16 compresses air continuously from the outside through the air supply lines G4 and G11, the bypass line G13, and the low pressure stage compressor 12a while compressing it. The auxiliary blower 16 continuously pumps the air pressurized by the compression action to the side of the engine body 1 as a combustion gas.

  In parallel to this, as described above, the low pressure supercharger 12 and the high pressure supercharger 13 rotate the low pressure compressor 12a and the high pressure compressor 13a by using the exhaust gas from the engine body 1, respectively. Let

  The low-pressure stage compressor 12a in the rotated state as described above sucks air (new air) from the outside through the air supply line G4 as a combustion gas, compresses the sucked combustion gas, and increases the pressure by this compression action. The combustion gas is pressure fed to the high pressure stage compressor 13a side. At this time, the combustion gas flows into the air supply line G4 from the outside through the filter and silencer of the air intake port by the suction action of the low pressure compressor 12a, the high pressure compressor 13a and the auxiliary blower 16. Next, the combustion gas is compressed in the first stage by the low pressure compressor 12a, and then flows from the low pressure compressor 12a into the air supply line G11 and is cooled by the intercooler 14. After that, it flows in the air supply line G11 toward the high pressure stage compressor 13a side.

  Here, the respective rotations of the low-pressure stage compressor 12a and the high-pressure stage compressor 13a using the exhaust gas from the engine main body 1 of the two-stage supercharger 11 may be insufficient compared with the stable operation time. In this case, the pressure increase of the combustion gas by the low-pressure stage compressor 12a is smaller than the target first-stage pressure increase. Similarly to this, the pressure increase of the combustion gas by the high pressure stage compressor 13a is smaller than the target second stage pressure increase.

  The pressure of the combustion gas delivered from the low pressure stage compressor 12a in such a state is the pressure of the combustion gas that has flowed from the auxiliary blower 16 through the bypass line G13 and the air supply line G14 into the gas outlet side of the check valve 17. Lower than. Therefore, the check valve 17 maintains the above-described closed state, thereby preventing the backflow of the combustion gas in the air supply line G14, and from the low pressure stage compressor 12a side into the air supply line G14. Cut off the flow of the combustion gas that has partially flowed.

  As described above, with the check valve 17 closed, the combustion gas from the low-pressure stage compressor 12a flows into the bypass line G13 through the air supply line G11 by the suction action of the auxiliary blower 16. The auxiliary blower 16 sucks the combustion gas flowing into the bypass line G13 and compresses the sucked combustion gas. At this time, the auxiliary blower 16 compresses the combustion gas supplementarily to compensate for the lack of the first stage compression by the low pressure stage compressor 12a and the lack of the second stage compression by the high pressure stage compressor 13a. Do. Subsequently, the auxiliary blower 16 pressure-feeds the combustion gas pressurized by the compression action to the engine main body 1 side. The combustion gas pressure-fed from the auxiliary blower 16 flows into the high pressure stage compressor 13a through the bypass line G13 and the air supply line G11.

  The high pressure stage compressor 13a is in the state of being rotated as described above, and the first stage compression is performed by the low pressure stage compressor 12a from the air supply line G11 and the auxiliary compression is performed by the auxiliary blower 16 Inhale the combustion gas. Next, the high-pressure stage compressor 13a further compresses the sucked combustion gas, and pressure-feeds the combustion gas further boosted by the compression action to the engine body 1 side. At this time, the combustion gas is subjected to auxiliary compression by the auxiliary blower 16, followed by second stage compression (boosting) by the high pressure stage compressor 13a, and thereafter, from the high pressure stage compressor 13a to the air supply line G1. Flow into Next, the combustion gas is cooled by the cooler 15 and then supplied to the scavenging trunk 3 of the engine body 1 through the air supply line G1.

  As described above, the two-stage supercharger 11 performs the two-stage supercharging of the combustion gas to the engine body 1 while the auxiliary blower 16 assists the pumping of the combustion gas, so that the inside of the scavenging trunk 3 is generated. The amount of combustion gas supplied is gradually increased to meet the amount required by the engine body 1.

  On the other hand, when the two-stage supercharger 11 starts to operate stably, the respective rotations of the low-pressure stage compressor 12a and the high-pressure stage compressor 13a using the exhaust gas from the engine body 1 become sufficient. In this case, both the first-stage boosting of the combustion gas by the low-pressure compressor 12a and the second-stage boosting of the combustion gas by the high-pressure compressor 13a satisfy the target boosting.

  The combustion gas pressure-fed from the low-pressure stage compressor 12a in such a state applies pressure to the check valve 17 from the gas inlet side through the air supply lines G11 and G14. The pressurizing force of the check valve 17 to the gas inlet side is higher than the pressure of the combustion gas flowing from the auxiliary blower 16 to the gas outlet side of the check valve 17 through the bypass line G13 and the air supply line G14. For this reason, the check valve 17 is automatically switched from the closed state described above to the open state. Thereby, the check valve 17 regulates the flow direction of the combustion gas in the air supply line G14 in one direction from the low pressure stage compressor 12a side to the high pressure stage compressor 13a side, while the low pressure stage compressor 12a The combustion gas pressure-fed into the air supply lines G11 and G14 is allowed to pass to the high pressure stage compressor 13a side.

  As described above, in the state where the check valve 17 is open, the combustion gas from the low-pressure stage compressor 12a is branched to the bypass line G13 and the air supply line G14 through the air supply line G11. The auxiliary blower 16 sucks and compresses the combustion gas branched into the bypass line G13. The auxiliary blower 16 combines the compressed combustion gas with the combustion gas from the air supply line G14 through the bypass line G13. The combustion gas branched into the air supply line G14 merges with the combustion gas from the auxiliary blower 16 as described above, and thereafter, the high-pressure stage compression in a state sufficiently rotated as described above through the air supply line G11. Flow into the machine 13a.

  The high-pressure stage compressor 13a sucks in from the air supply line G11 the combustion gas for which the first-stage compression has been sufficiently performed, further compresses the sucked combustion gas, and pressure-feeds it to the engine main body 1 side. At this time, the combustion gas is sufficiently compressed (boosted) at the second stage by the high-pressure stage compressor 13a. Thereafter, the combustion gas flows from the high-pressure stage compressor 13a into the air supply line G1, is cooled by the cooler 15, and is then supplied to the scavenging trunk 3 of the engine body 1. In this manner, the two-stage supercharging of the combustion gas to the engine body 1 is sufficiently performed, whereby the amount of combustion gas supplied in the scavenging trunk 3 is maintained at the amount required by the engine body 1 It can be done.

  On the other hand, while the two-stage supercharger 11 is in stable operation, the pressure of the combustion gas in the scavenging air trunk 3 is increased above the predetermined threshold value. In this state, the control unit 18 determines that the detected value of the pressure of the combustion gas by the pressure detection unit 8 is equal to or higher than a predetermined threshold, and stops the operation of the auxiliary blower 16. The auxiliary blower 16 stops the pumping of the combustion gas to the engine body 1 based on the control by the control unit 18.

  Specifically, the low-pressure stage compressor 12a continuously performs the first-stage compression on the air drawn in from the outside as the combustion gas, continuing from the state where the stable operation started as described above, and this compression is performed The combustion gas is pressure fed to the high pressure stage compressor 13a side. The combustion gas pressure-fed from the low pressure stage compressor 12a is cooled by the intercooler 14 while flowing in the air supply line G11, and then flows into the high pressure stage compressor 13a through the check valve 17 . At this time, the backflow of the combustion gas from the high pressure stage compressor 13a to the low pressure stage compressor 12a via the bypass line G13 flows from the low pressure stage compressor 12a to the high pressure stage compressor 13a through the air supply line G11. It is prevented by the pressure of the combustion gas.

  The high-pressure stage compressor 13a continuously performs the second-stage compression on the combustion gas from the low-pressure stage compressor 12a continuously from the state where stable operation has started as described above, and the compressed combustion gas is Pump to engine body 1 side. The combustion gas pressure-fed from the high-pressure stage compressor 13a is cooled by the cooler 15 while flowing in the air supply line G1, and thereafter, is supplied to the scavenging air trunk 3.

  As described above, in the marine diesel engine 10 according to the embodiment of the present invention, the turbocharger is a drive-type supercharger that rotates the compressor using the exhaust gas discharged from the engine main body 1, and the combustion is performed from the outside Low pressure supercharger 12 (first supercharger) that sucks in and compresses gas and the combustion gas compressed by the low pressure supercharger 12 is further compressed and fed to the engine main body 1 Stage turbocharger 13 (second turbocharger) and the compressor of the low pressure stage turbocharger 12 (low pressure stage compressor 12a) to the compressor of the high pressure stage turbocharger 13 (high pressure stage compressor 13a) In the air supply line G11 through which the combustion gas is circulated, an auxiliary blower 16 that assists the supply of the compressed combustion gas to the engine body 1 is provided.

  As a result, the auxiliary blower 16 sucks in the combustion gas from the outside and pumps it to the engine body 1 through a pipe that allows the combustion gas from the outside to flow to the engine body 1 through the low pressure compressor 12a and the high pressure compressor 13a. Can be shared as piping for For this reason, even if a switching valve for switching the flow path of the combustion gas is not provided in the pipe, the flow path of the combustion gas from the outside through the low pressure compressor 12a and the high pressure compressor 13a to the engine main body 1 and A pipeline combining the flow path of the combustion gas leading to the engine body 1 through the blower 16 can be formed with a simple piping configuration. Furthermore, when delivering the combustion gas compressed by the low-pressure stage compressor 12a or the auxiliary blower 16 toward the high-pressure stage compressor 13a, the flow path of the combustion gas does not need to be switched by the switching valve. It is not necessary to provide a control system for controlling the complicated opening / closing drive of the switching valve at the time of path switching. Therefore, for example, as compared with the conventional diesel engine in which the low-pressure stage compressor, the high-pressure stage compressor, and the auxiliary blower are connected by piping via the switching valve as disclosed in Patent Document 1 described above, A plurality of turbochargers such as the feeder 12 and the high pressure stage turbocharger 13 can be combined with the auxiliary blower 16 with a simple configuration.

  Further, as described above, since the pipe leading to the low pressure stage compressor 12a and the high pressure stage compressor 13a and the pipe leading to the auxiliary blower 16 are shared, the pipes leading to the low pressure stage compressor 12a and the high pressure stage compressor 13a The existing components provided at the air inlet, for example, a filter for preventing foreign substances from being sucked, a silencer for reducing noise at the time of fresh air suction, etc., when suctioning combustion gas by the auxiliary blower 16 It can be shared. This makes it possible to reduce the number of parts required for the piping configuration of the marine diesel engine 10 as much as possible, and as a result, it is possible to promote the reduction of labor and cost for the piping configuration.

  Furthermore, an auxiliary blower 16 is provided in the air supply line G11 between the low pressure stage compressor 12a and the high pressure stage compressor 13a. Therefore, among the low-pressure stage compressor 12a and the high-pressure stage compressor 13a, which can be a large flow resistance in the flow path of the combustion gas because the area through which the combustion gas can pass is small, the auxiliary blower 16 sucks the combustion gas from the outside The main flow resistance in carrying out can be limited only to the low pressure stage compressor 12a. Thereby, the configuration when the auxiliary blower 16 is provided in the air supply line G1 between the engine body 1 and the high pressure stage compressor 13a, for example, is disclosed in FIGS. 2 and 3 of the above-mentioned Patent Document 1 The flow resistance at the time of suction of the combustion gas by the auxiliary blower 16 can be reduced as compared with the configuration of the conventional diesel engine. As a result, the power (for example, motor power) necessary for suctioning the combustion gas by the auxiliary blower 16 can be reduced, thereby promoting the reduction of cost and energy such as electric power applied to the drive source such as the motor of the auxiliary blower 16. it can.

  In the marine diesel engine 10 according to the embodiment of the present invention, the high pressure stage turbocharger 13 side to the low pressure stage turbocharger 12 side in the air supply line G11 between the low pressure stage compressor 12a and the high pressure stage compressor 13a. The check valve 17 is provided to prevent the backflow of the combustion gas to the lower side, and the air supply line G11 is branched into two between the low-pressure stage compressor 12a and the check valve 17 to set the check valve 17 and the high pressure The auxiliary blower 16 is provided in the first branch pipe (bypass line G13) of the two branched air supply lines G11 so as to form a flow pipe joining with the stage compressor 13a. The non-return valve 17 is provided in the branch pipe (air supply line G14) of this. Therefore, the pressure difference between the combustion gas on the gas inlet side of the check valve 17 and the combustion gas on the gas outlet side simply and automatically in the air supply line G11 without performing the drive control of the valve opening and closing. The flow direction of the combustion gas can be regulated in one direction from the low pressure stage compressor 12a side to the high pressure stage compressor 13a side, and the backflow of the combustion gas in the opposite direction can be prevented.

  Furthermore, since the check valve 17 is provided between the low pressure compressor 12a and the high pressure compressor 13a so as to be connected in parallel with the auxiliary blower 16, the combustion valve added to the check valve 17 is provided. The pressure of the gas is lower than the combustion gas compressed in two stages by the low pressure stage compressor 12a and the high pressure stage compressor 13a, that is, the combustion gas by the compression action of the low pressure stage compressor 12a or the auxiliary blower 16 It can be kept at pressure. For this reason, since it is not necessary to make the pressure-resistant structure of the check valve 17 into a special structure that can withstand high pressure, it is possible to use a normal pressure-resistant check valve (for example, commercially available one) as the check valve 17 As a result, the cost increase of the check valve 17 can be suppressed.

  Further, the combustion gas pressure-fed by the auxiliary blower 16 is joined to the air supply line G11 between the check valve 17 and the high pressure stage compressor 13a. For this reason, the configuration in the case where the gas outlet side of the auxiliary blower 16 is connected by piping to the air supply line G1 between the engine body 1 and the high pressure stage compressor 13a, for example, FIGS. Compared with the configuration of the conventional diesel engine disclosed in the figure, the combustion gas from the auxiliary blower 16 can be merged with the combustion gas flowing in the piping at a low pressure. As a result, the power required for pumping the combustion gas by the auxiliary blower 16 can be reduced, and thus the cost of driving the auxiliary blower 16 and the reduction of energy such as electric power can be further promoted.

  Further, in the marine diesel engine 10 according to the embodiment of the present invention, a cooler (specifically, the intercooler 14) for cooling the combustion gas in the air supply line G11, the low-pressure stage compressor 12a and the check valve It is arranged between 17 and. Therefore, the temperature of the combustion gas flowing into the check valve 17 through the air supply line G11 after being compressed by the low-pressure stage compressor 12a may be lowered to a temperature equal to or lower than the upper temperature limit of the check valve 17. it can. As a result, deterioration due to heat of the check valve 17 can be suppressed, and as a result, prolongation of the life of the check valve 17 can be promoted.

  In the marine diesel engine 10 according to the embodiment of the present invention, the pressure of the combustion gas supplied to the engine main body 1 is detected, and the auxiliary blower 16 is used when the detected pressure value is less than a predetermined threshold. When activated and the detected pressure value is equal to or higher than a predetermined threshold value, the auxiliary blower 16 is stopped operating. Therefore, the auxiliary blower 16 can be operated in a timely manner when the auxiliary blower 16 needs to assist the pumping of the combustion gas, specifically, during start-up or low load operation of the engine main body 1, The operation of the auxiliary blower 16 can be timely stopped while the load is sufficiently increased and both the low pressure supercharger 12 and the high pressure supercharger 13 are in stable operation. As a result, the timing of drive control of the auxiliary blower 16 and the waste of energy consumption can be reduced to optimize them.

  In the embodiment described above, the case where the two-stage supercharger 11 having the two superchargers (the low pressure supercharger 12 and the high pressure supercharger 13) is applied to the engine body 1 has been exemplified. The present invention is not limited to this. For example, a multistage turbocharger may be applied to the engine body 1 in which the combustion gas is compressed stepwise by a plurality of (two or more) turbochargers. In this case, a plurality of low pressure superchargers 12 may be provided among the low pressure supercharger 12 and the high pressure supercharger 13 constituting the multistage supercharger, and a plurality of high pressure superchargers 13 may be provided. It may be provided or may be a combination of these.

  Further, in the embodiment described above, the air supply line G11 which is branched and joined into two between the low pressure stage compressor 12a and the high pressure stage compressor 13a is exemplified, and the auxiliary blowers 16 are connected to the respective branch pipes of the air supply line G11. And the check valve 17 are arranged in parallel, but the present invention is not limited to this. For example, the air supply line G11 may be a non-branched flow pipe, and the auxiliary blower 16 and the check valve 17 may be arranged in series along the air supply line G11. Alternatively, the backflow of the combustion gas in the air supply line G11 may be prevented by the drive of the auxiliary blower 16. In this case, the check valve 17 may not be provided in the air supply line G11.

  Furthermore, in the embodiment described above, the control unit 18 determines the pressure of the combustion gas detected by the pressure detection unit 8 (the pressure of the combustion gas supplied into the scavenging trunk 3 of the engine main body 1). The drive control of the auxiliary blower 16 is performed, but the present invention is not limited to this. For example, the control unit 18 may drive-control the auxiliary blower 16 according to the engine load, or the auxiliary blower 16 may be controlled based on at least one of the rotational speeds of the low pressure supercharger 12 and the high pressure supercharger 13. Drive control may be performed.

  In the above-described embodiment, air (fresh air) sucked from the outside is used as the combustion gas, but the present invention is not limited to this. For example, an EGR system may be further provided to recirculate a part of the exhaust gas from the engine body 1 to the engine body 1, and a mixed gas of recirculation gas from the EGR system and air from the outside may be used as the combustion gas. .

  Furthermore, in the embodiment described above, the engine body 1 (six-cylinder engine) provided with six cylinders 2 is illustrated, but the present invention is not limited to this. The number of cylinders 2 provided in the engine body 1 may be any desired number (one or more). Similarly, the arrangement number of the fuel injection pump 6 and the fuel injection valve 7 of the injection unit 5 is not limited to that described above, but may be a necessary number (one or more) according to the arrangement number of the cylinders 2 . That is, in the present invention, the number of arrangement of each component of the cylinder 2 and the injection unit 5 is not particularly limited.

  Further, the present invention is not limited by the above-described embodiment, and the present invention also includes those configured by appropriately combining the above-described respective constituent elements. In addition, other embodiments, examples, operation techniques and the like made by those skilled in the art based on the above-described embodiments are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 engine body 2 cylinder 3 scavenging air trunk 4 exhaust manifold 5 injection part 6 fuel injection pump 7 fuel injection valve 8 pressure detection part 10 marine diesel engine 11 two-stage supercharger 12 low pressure stage supercharger 12a low pressure stage compressor 12b low pressure Stage turbine 12c, 13c Rotor shaft 13 High pressure stage turbocharger 13a High pressure stage compressor 13b High pressure stage turbine 14 Intercooler 15 Cooler 16 Auxiliary blower 17 Check valve 18 Control section 25 Exhaust port 71 Base plate 72 Structure 73 Cylinder jacket 74 tie bolt 75 nut 76 cylinder liner 77 cylinder cover 78 piston 79 exhaust valve 80 valve gear 81 piston rod 82 crank shaft 83 bearing 84 crank 85 connecting rod 86 guide plate 87 cross head 88 cross head pin G1, G4, G11, G 14 Air Supply Line G2, G3, G12 Exhaust Line G13 Bypass Line

Claims (2)

An engine body that burns fuel to generate propulsion of a ship;
A first turbocharger which sucks in and compresses a combustion gas from the outside by rotating a compressor using exhaust gas discharged from the engine body;
A second turbocharger that further compresses the combustion gas compressed by the first turbocharger by feeding the exhaust gas to the engine body by rotating the compressor using the exhaust gas;
A flow pipe for distributing a combustion gas from the compressor of the first turbocharger to the compressor of the second turbocharger;
An auxiliary blower provided in the flow pipe for assisting the delivery of the compressed combustion gas to the engine body;
A check valve for preventing the backflow of the combustion gas from the second turbocharger side to the first turbocharger side in the flow pipe;
A pressure detection unit that detects the pressure of the combustion gas supplied to the engine body;
A control unit that operates the auxiliary blower if the detected pressure value is less than a predetermined threshold value, and stops the operation of the auxiliary blower if the detected pressure value is equal to or greater than the threshold value;
Equipped with
The flow pipe is bifurcated between the compressor of the first turbocharger and the check valve, and the flow is merged between the check valve and the compressor of the second turbocharger. Is a tube,
Among the flow pipes branched into two, the first branch pipe is provided with the auxiliary blower, and the second branch pipe is provided with the check valve,
The combustion gas supplied to the engine body in the case where the pressure from the first turbocharger side in the check valve is higher than the pressure from the second turbocharger side in the check valve. Set to a value above the pressure of the
When the detected pressure value increases from below the threshold value to above the threshold value, the auxiliary blower compresses the combustion gas in the first branch pipe in a state in which the check valve is open, and the second A marine diesel engine characterized by stopping operation through merging with a combustion gas in a branch pipe . The marine diesel engine according to claim 1, further comprising a cooler disposed between the compressor of the first turbocharger and the check valve and cooling the combustion gas in the flow pipe. .

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