JP3875067B2 - Diesel engine with turbocharger - Google Patents

Description

[0001]
[Field of the Invention]
[0002]
  The present invention relates to a diesel engine with a supercharger. More particularly, the present invention relates to a diesel engine with a supercharger used as a main engine of an underwater work boat.
[Background Art and Problems to be Solved by the Invention]
[0003]
  Generally, a diesel engine is adopted as a main engine of an underwater work boat. Since this underwater work boat is used in a state where the hull is submerged in water, the intake pipe of the diesel engine protrudes from the water into the air above the water surface. On the other hand, the exhaust pipe extends underwater from the hull, and its outlet is submerged in water. Therefore, since water tends to enter from the outlet of the exhaust pipe, it is necessary to prevent this water from entering. Conventionally, water entering the exhaust pipe is ejected by the momentum of the exhaust flow to prevent entry. Specifically, a measure is taken to increase the flow rate of exhaust gas by providing a throttle (hereinafter referred to as “exhaust outlet throttle”) for preventing the backflow of water in the middle of the exhaust pipe.
[0004]
  In general, the main engine is equipped with a mechanically driven supercharger. This is to reduce the size and weight of the diesel engine and to increase the efficiency, and to exhaust the water sufficiently to prevent water from entering the exhaust pipe even when the diesel engine is under low load, for example, at no-load rated speed. This is to ensure the capacity and to make the exhaust flow velocity sufficient. Here, the mechanical supercharger is driven by obtaining power from the output shaft of a diesel engine. Therefore, in order to increase the exhaust flow rate in addition to increasing the efficiency of the diesel engine, if the function of this mechanical supercharger is sufficiently used, it is necessary to increase the output of the mechanical supercharger accordingly. . As a result, much of the power generated by the diesel engine is consumed to drive the supercharger, and the effective output of the diesel engine is reduced.
[0005]
  On the other hand, it is conceivable to reduce the inner diameter (throttle diameter) of the throttle in order to increase the exhaust flow velocity at the exhaust outlet throttle without increasing the output of the supercharger at low load. However, if the throttle diameter is reduced, the exhaust gas temperature naturally rises and the volumetric flow rate of the exhaust gas increases when the load on the diesel engine increases. That is, when the engine is operated at a constant rotational speed, the weight flow rate of the exhaust gas is basically constant, but when the temperature of the exhaust gas rises, its volume flow rate increases due to thermal expansion. Therefore, in the structure in which the diameter of the exhaust outlet throttle is reduced, the exhaust flow velocity becomes larger than necessary when the load increases, and the back pressure also becomes very large. For this reason, the intake air amount of the diesel engine is relatively insufficient, and the temperature of the exhaust gas further rises and becomes higher than that during normal operation. As a result, the burden on the diesel engine increases, and as a result, the upper limit of the output of the diesel engine has to be set extremely small, resulting in a reduction in efficiency.
[0006]
  The present invention has been made to solve such a problem, and can effectively prevent water from entering the exhaust pipe (back flow of water through the exhaust outlet throttle) while avoiding a decrease in output efficiency. The object is to provide a turbocharged diesel engine.
[Means for Solving the Problems]
[0007]
  If this inventor bypasses to the exhaust pipe without supplying a part of the air pressurized by the centrifugal blower type mechanical supercharger to the cylinder of the operating (combusting) diesel engine, the supercharger The discharge side pressure was reduced, and the discharge flow rate could be increased without increasing the driving force of the supercharger. That is, the discharge amount increases as the ratio of the outlet pressure to the inlet pressure of the centrifugal blower (pressure ratio) decreases. On the other hand, for the supercharger, the diesel engine is grasped as a “throttle” on the discharge side of the supercharger. Therefore, a configuration in which a part of the air discharged by the turbocharger is supplied to the exhaust pipe without going through the operating diesel engine, that is, the inner diameter of the “throttle” on the discharge side of the turbocharger. This is equivalent to increasing (equivalent aperture diameter).
[0008]
  As a result, a part of the air from the supercharger is sent to the exhaust pipe bypassing the burning cylinder of the diesel engine, so that the pressure on the discharge side of the supercharger is reduced and the discharge flow rate of the supercharger is reduced. To increase.
[0009]
  Therefore, the turbocharged diesel engine according to the present application is
Applied to underwater work boat,A V-type four-cycle diesel engine in which air is supercharged by a centrifugal blower type mechanical supercharger,
  Valve timing for one cylinder rowThe4 cyclesNon-combustion that repeats only the intake and exhaust strokesSwitch to cycleA switching device;
  This non-burningFuel injection into one of the cylinder rows during a cycleTheStopA control device,
  An exhaust pipe for exhausting into the water, wherein the exhaust port of the one cylinder row and the exhaust port of the other cylinder row are connected together;
  The air discharged from the one cylinder row and the exhaust gas from the other cylinder row during the non-combustion cycle are collectively discharged from the exhaust pipe.It is comprised so that it may be performed.
[0010]
  According to this configuration, the valve timing of one cylinder row of the diesel engine is adjusted.Non-combustion that repeats only the intake and exhaust strokesYou can switch to a cycle. And thisNon-combustionFuel is not injected into the cylinder row switched to the cycle. In this way, a part of the air pressurized by the centrifugal blower type mechanical supercharger is not operated in the diesel engineNon-combustionIt will be sent to the exhaust pipe through (bypassing) the cylinder row of the cycle, i.e., the cylinder row not burning inside.Non-combustionThe cycle cylinder row has twice the displacement per unit time as compared to the four-cycle cylinder row in operation, and the entire diesel engine has 1.5 times the displacement. The equivalent throttle diameter on the discharge side for the supercharger increases correspondingly, and the discharge side pressure of the supercharger also decreases. That is, the pressure ratio of the supercharger decreases, and the exhaust flow velocity passing through the exhaust outlet throttle increases from the blower characteristics described later. As a result, the exhaust flow velocity can be increased without having to reduce the actual exhaust outlet throttle diameter.
[0011]
  This means that when the load of the diesel engine is small, for example, when there is no rated load rotation and the exhaust gas temperature is low, a sufficient volume flow rate does not occur in the exhaust pipe, and thus a sufficient exhaust flow velocity is generated. Even when not possible, the turbocharger is not burningNon-combustionBy sending air to the cylinder row of the cycle, it is possible to increase the flow velocity in the exhaust pipe and prevent water from entering.
[0012]
  Also,Non-combustionThe cylinder row of the cycle is not a mere bypass path, but has a forced pneumatic feeding function by a piston, that is, a pumping function. Therefore, even if the water head at the position of the outlet of the exhaust pipe becomes larger due to the influence of, for example, waves on the water surface, it is possible to obtain a large exhaust flow velocity regardless of this variation in depth pressure.
[0013]
  When the load of the diesel engine is equal to or greater than a certain threshold, the valve timing of the one cylinder row isNon-combustionA diesel engine configured to be switched from four cycles to four cycles is preferable.
[0014]
  In this way, when the load of the diesel engine is less than a certain threshold, that is, when the load is small and the need for supercharging the diesel engine is low, the valve timing of one cylinder row is set.Non-combustionCycle the pressurized airNon-combustionThis is because the exhaust gas can be fed to the cycle cylinder row to ensure the sufficient exhaust flow velocity. Therefore, it is not necessary to reduce the actual exhaust outlet throttle diameter. When the load on the diesel engine increases and exceeds a certain threshold, thisNon-combustionThe cycle cylinder row is switched to 4 cycles. Since the actual exhaust outlet throttle diameter is not originally reduced, the exhaust temperature does not rise more than necessary even if the volume flow rate of the exhaust gas increases during load operation.
[0015]
  Also,DeLoad sensor for detecting the load on a diesel engineFurther equipped,The control device isThe switching device is driven based on the load detected by the load sensor.Configured asA diesel engine is preferable.
[0016]
  This is because the cycle can be switched while monitoring the load of the diesel engine by the load sensor. Therefore, if the load on the diesel engine is small, the need for supercharging for combustion is low, and the exhaust temperature of the diesel engine is low, one cylinder row should be installed.Non-combustionBy switching to the cycle, the air from the supercharger can be supplied to the exhaust pipe bypassing the four-cycle cylinder row during combustion. As a result, as described above, the flow rate of the air passing through the exhaust outlet throttle can be sufficiently increased to prevent water from entering the exhaust pipe.Further, it is preferable to provide a fixed throttle in the exhaust pipe.
[0017]
  Further, the switching device comprises a cam mechanism for opening and closing the intake valve and the exhaust valve of the one cylinder row,
  The cam mechanism includes a cam for four cycle timing andNon-combustionA cam for cycle timing and a camshaft in which these cams are fixed in series;
  The above control device moves the camshaft in the axial direction thereof, therebyNon-combustionA diesel engine configured to switch between the cam for cycle timing is preferable.
[0018]
  According to this configuration, the cycle of one cylinder row can be switched by moving the camshaft in the axial direction when necessary, so that extremely easy and quick switching is possible.
DETAILED DESCRIPTION OF THE INVENTION
[0019]
  Hereinafter, an embodiment of a diesel engine with a supercharger according to the present invention will be described.
[0020]
  FIG. 1 schematically shows the structure of an underwater work boat 2 equipped with a diesel engine (hereinafter simply referred to as “engine”) 1 according to an embodiment of the present invention. The engine 1 is a V-type four-cycle engine, and the intake valve and exhaust valve of each cylinder are opened and closed by cams. Both valves may be opened and closed directly by a cam, or both valves may be opened and closed by a cam via a rocker arm.
[0021]
  This underwater work boat 2 is used, for example, to clean the bottom of the harbor while navigating at a certain depth or less, and is of a type that is submerged in water. Since the engine 1 is an internal combustion engine using air, the air is sucked through the air introduction pipe 12 projecting from the hull 3 into the air, and the exhaust gas is discharged from the exhaust outlet hardware 5 into the water through the exhaust pipe 14. As described above, the exhaust gas is discharged into the water, so that it is necessary to prevent water from entering the exhaust pipe 14. Therefore, a fixed throttle (exhaust outlet throttle) 24 is disposed in the exhaust pipe 14 as will be described later. Here, if the upstream part of the exhaust pipe 14 from the exhaust outlet throttle 24 is called an upstream exhaust pipe part 14 a and the downstream part of the exhaust outlet throttle 24 is called a downstream exhaust pipe part 14 b, the upstream exhaust pipe part is defined by the exhaust outlet throttle 24. It is intended to prevent water from entering 14a.
[0022]
  A feature of this embodiment is an air supply mechanism of the engine 1. That is, if necessary, a part of the supply air is sent to the exhaust pipe, bypassing the operating cylinder. Specifically, fuel is not injected into one cylinder row of the V-shaped two rows of cylinder rows, and fuel is injected and burned only into the other cylinder row. A part of the atmosphere (air) taken in as combustion air is supplied to the burning cylinder row, and the cylinder row not burning the remaining air is sent to the exhaust pipe 14 as a bypass path. By doing so, it is possible to increase the exhaust flow velocity in the exhaust outlet throttle 24 without imposing a heavy burden on the engine 1 to prevent water from entering and to increase the upper limit of the engine output. It is. This will be described in detail below.
[0023]
  The underwater work boat 2 includes a hull 3, an engine 1 mounted in the hull 3, a generator 7 driven by the engine 1, a propulsion device 8 driven by electricity generated by the generator 7, and other functions. Parts (not shown). Various functional parts are employed depending on the work contents of the underwater work boat 2. Therefore, the load of the engine 1 can be determined by the magnitude of electric power (electrical output of the generator 7) necessary for driving the propulsion device 8 and other functional components.
[0024]
  FIG. 2 is a block diagram showing the arrangement of the engine 1 and its air supply mechanism. The engine 1 includes an engine body 11, an air introduction pipe 12, an intake pipe 13, and an exhaust pipe 14. The engine body 11 is provided with a mechanically driven supercharger (hereinafter simply referred to as “supercharger”) 16 connected to the output shaft 15. The supercharger 16 includes an input shaft 17 connected to the output shaft 15, a gear train 18 and a drive shaft 19 connected to the input shaft 17, and a centrifugal blower 20 connected to the drive shaft 19. ing. The blower 20 is interposed in the intake pipe 13 so that the air on the air introduction pipe 12 side is pressurized to a predetermined supercharging pressure and sent to the engine 1 side of the intake pipe 13. Here, the centrifugal blower type mechanical supercharger 16 is used because the discharge amount can be increased by lowering the discharge side pressure of the supercharger 16 as described later.
[0025]
  The air introduction pipe 12 projects from the hull 12 onto the water surface and can be formed of, for example, a stainless steel pipe. The air supply pipe 13 connects the air introduction pipe 12 and the intake port 21 of the engine body 11. A cooling device 22 is disposed in the middle of the intake pipe 13 (upstream of the intake port 21). The cooling device 22 is a so-called intercooler, which cools the air in the intake pipe 13 that has been supercharged and becomes high temperature and sends it to the intake port 21. The cooling device 22 is water-cooled, and cooling water is sucked from outside the hull by a pump (not shown).
[0026]
  The exhaust pipe 14 can be constituted by, for example, a stainless steel pipe or the like, and is connected to the exhaust port 23 of the engine body 11.Exhaust pipe 14The outlet of the exhaust outlet hardware5To the outside of the hull 3. As described above, the exhaust outlet throttle 24 is disposed on the downstream side of the upstream exhaust pipe portion 14a. The exhaust outlet throttle 24 effectively increases the exhaust flow velocity.
[0027]
  Next, the engine body 11 is a V-type engine in which the two cylinder rows 25a and 25b are formed in a V shape as described above, and in principle, operates in four cycles. However, only one cylinder row 25a has a valve timing of 4 cycles.Non-combustiblecycle(Cycles that repeat only the intake and exhaust strokes, as will be described later)And can be switched toNon-combustionThe fuel injection is stopped during the cycle operation. Then, a switching device 26 that switches the valve timing of the one cylinder row 25a, and a control device that controls the switching of the valve timing of one cylinder row 25a and the stop of fuel injection in accordance with the load of the engine 1. 27 and a load sensor 28 for monitoring the load of the engine 1 are provided. The load sensor 28 monitors the output of the generator 7 and outputs a load signal S1 indicating that the load is large when the output exceeds a certain value. The load signal S1 is input to the control device 27. The control device 27 operates the switching device 26 based on the load signal S1 to adjust the valve timing of one cylinder row 25a.Non-combustionSwitch from cycle to 4 cycles.
[0028]
  FIG. 3 shows an example of the switching device 26. The switching device 26 has cams 30 and 31 for pressing the rocker arm 29 of one cylinder row 25a, a cam shaft 32 provided with a plurality of the cams, and reciprocates the cam shaft 32 in the axial direction. And a moving device (not shown). In addition, since this moving apparatus can employ | adopt a known thing, description of the structure is abbreviate | omitted. The camshaft 32 has a single cylinder,Non-combustionCam 30a and cam 30b for exhaust valve 33b having a profile for cycle operation, cam 31a and cam for exhaust valve 33b having a profile for four cycle operation A pair of 31b is arranged in series. 3A which is a plan viewNon-combustionThe state of the cycle is indicated by a solid line, and the camshaft 32 is shown in the figure.DownThe state of 4 cycles displaced by the two-dot chain line is shown. In FIG. 3A, the intake valve cams 30a and 31a are arranged close to each other, and the exhaust valve cams 30b and 31b are arranged close to each other. It is not limited. For example,Non-combustionThe cycle cam pairs 30a and 30b may be disposed close to each other, and the four-cycle cam pairs 31a and 31b may be disposed close to each other.
[0029]
  FIG. 4 is a graph showing the piston stroke of both cylinder rows 25a and 25b with respect to their valve timing. For one cylinder row 25a shown in the upper part of the figure, when the engine 1 is in a no-load operation at the rated speed and a low-load operation close to this (range L in the figure), there is no fuel injection.Non-combustionIt operates in a cycle and there is no compression or explosion stroke. When the load increases and exceeds a predetermined value (range H in the figure), the switching device 26 switches to four cycles based on the signal S1 from the load sensor 28. At the same time as switching to four cycles, fuel injection is started at a predetermined four cycle timing, and one cylinder row 25a also generates power as a prime mover. In the state where the load signal S1 is not output, the switching device 26 is always used.Non-combustionThe valve timing for cycle operation is used. The other cylinder row 25b always burns at the valve timing of 4 cycles.
[0030]
  In this way, in the range L in the figure, part of the air pressurized by the supercharger 16 contributes to combustion in the other four-cycle operating cylinder row 25b, and the rest does not burn.Non-combustionIt is sent to the cycle operating cylinder row 25a. Therefore, for the four-cycle operating cylinder row 25b during combustion,Non-combustionThe cycle operating cylinder row 25a serves as a bypass path through which a part of the compressed air from the supercharger 16 passes.Non-combustionThe cycle operation cylinder row 25a has twice as many intake strokes / exhaust strokes per unit time as the 4-cycle operation cylinder row 25b. Therefore, the displacement of one cylinder row 25a is twice that of the other cylinder row 25b during combustion per unit time. In the entire engine, the displacement is 1.5 times that of when both cylinder rows are operating for 4 cycles. As a result, the equivalent throttle diameter on the discharge side for the supercharger 16 increases correspondingly, and the discharge side pressure of the supercharger also decreases. Also,Non-combustionThe cycle operating cylinder row 25a is not a mere bypass path, but can be said to be a bypass path having a forced pneumatic feeding function by a piston. These points will be described below.
[0031]
  FIG. 5 is a diagram (blower characteristic diagram) showing characteristics of the centrifugal blower 20 of the supercharger 16 according to the present embodiment. The vertical axis represents the pressure ratio (the ratio between the suction side pressure P1 and the discharge side pressure P2 of the blower, P2 / P1), and the horizontal axis represents the volume flow rate QV of air from the blower in the standard state. A solid line K indicates a surging line of the blower 20, and surging occurs on the left side of the solid line K, which cannot be put into practical use. In addition, the solid lines L1 to L4 are obtained when the pressure P2 on the discharge side is changed with the rotation speed of the blower 20 (equivalent to the rotation speed of the engine 1) being constant, and as a result, the pressure ratio P2 / P1 is changed. This shows the relationship between the pressure and volume flow rate. In particular, the solid line L2 indicates the change in the air state at the rated speed of the engine 1. As shown in the figure, the air pressurized by the supercharger 16 has a characteristic that when the throttle on the discharge side increases (resistance decreases), the pressure decreases and the volume flow rate increases.
[0032]
  Here, when attention is paid to the path where the air pressurized by the supercharger 16 reaches the exhaust pipe 14 through the engine 1, the engine 1 is the first “throttle” and the exhaust outlet throttle 24 is the second in this path. It is understood as “aperture”. Further, since the equivalent diameter of the throttle of the engine 1 is much smaller than the diameter of the exhaust outlet throttle 24, a part of the air pressurized by the supercharger 16 is partly non-combusted.GrilledIccleofFeeding to the exhaust pipe 14 through the cylinder row 25a is equivalent to increasing the “engine equivalent throttle” of the flow path, that is, increasing the diameter of the throttle. Therefore, as described above, as the throttle diameter increases as a whole in the path from the supercharger 16 to the exhaust pipe 14, the discharge-side pressure P2 of the supercharger 16 decreases and the pressure ratio P2 / P1 decreases. It will be.
[0033]
  This will be described with reference to FIG. In FIG. 5, point A indicates the operating point when air discharged from the supercharger 16 is supplied to both cylinder rows when both cylinder rows are operating for 4 cycles, and point B is supercharged. Non-combustion of part of the air discharged from the machine 16ofThe operating point when the exhaust pipe 14 is fed through the cycle operating cylinder row 25a is shown. As the operating point moves from point A to point B, that is, the pressure ratio P2 / P1 decreases, the volume flow rate in the exhaust pipe 14 increases due to the blower characteristics.
[0034]
  Therefore, in this embodiment, when the load of the engine 1 is small (for example, at no-load rated rotation), the exhaust temperature is low and a sufficient exhaust flow velocity cannot be generated in the exhaust outlet throttle 24. Even the above pressurized airNon-combustionBy supplying the exhaust pipe 14 through the cycle operating cylinder row 25a, the exhaust flow velocity passing through the exhaust outlet throttle 24 can be increased to prevent water from entering the upstream exhaust pipe portion 14a.
[0035]
  As mentioned above,Non-combustionThe cycle operating cylinder row 25a is not a simple bypass path but has a forced air pressure feeding function by a piston. In other words, the engine functions as a check valve against the back flow of water. Therefore, even if the head of the outlet of the downstream exhaust pipe portion 14b becomes large due to the influence of waves on the water surface, for example, it is possible to obtain a large exhaust flow velocity regardless of the variation in depth pressure.
[0036]
  As described above, in this embodiment, a part of the compressed air from the supercharger 16 is removed.Non-combustionBy bypassing to the exhaust pipe 14 through the cycle operating cylinder row 25a, a sufficient exhaust flow velocity in the exhaust outlet throttle 24 can be secured even during no-load operation at the rated rotational speed. Therefore, it is possible to prevent water from entering without reducing the inner diameter of the exhaust outlet throttle 24. It is also possible to increase the inner diameter of the exhaust outlet throttle 24 as necessary. As a result, even when the exhaust temperature of the engine 1 becomes high during load operation in which both the cylinder rows 25a and 25b are burned in four cycles, and as a result, the volume flow rate of the exhaust gas increases, the upstream exhaust pipe portion 14a. It is possible to avoid a significant increase in the back pressure generated inside. As a result, the upper limit of the output of the engine 1 can be set large and the efficiency can be improved.
[0037]
  In general, it is preferable that the engine 1 is operated at the rated rotation speed (running at the maximum rotation speed) from the start-up regardless of the load. In high load operation at the rated speed, the volume flow rate increases as the exhaust gas temperature rises. Therefore, when the inner diameter of the exhaust outlet throttle 24 is reduced, the back pressure in the upstream exhaust pipe portion 14a becomes very large. The burden on the engine 1 is increased. However, in the present embodiment, it is not necessary to reduce the inner diameter of the exhaust outlet throttle 24 (because it can be increased), so that back pressure that imposes a heavy burden on the engine 1 is generated even when the high load operation is always performed. There is no.
[0038]
  The underwater work boat 2 having the above configuration has the following operational effects.
[0039]
  First, in general, when the engine is under a low load, the exhaust gas has a low volumetric flow rate because the exhaust temperature is low even if the engine 1 is maintained at the rated speed, and the flow rate in the exhaust pipe 14, that is, the exhaust outlet throttle 24. Low flow rate. However, in this embodiment, at the time of such a low load, one cylinder row 25a isNon-combustionSince the cycle operation is performed, a part of the compressed air from the supercharger 16 can be fed into the exhaust pipe 14 through the cylinder row 25a to increase the exhaust flow velocity in the exhaust outlet throttle 24. Further, in the present embodiment, when the load exceeds a certain threshold value, this is detected by the load sensor 28, the fuel injection to the cylinder row 25a is started by the control device 27, and the switching device 26 operates for 4 cycles. Switch to. Thereby, the maximum output can be generated during high load operation.
【The invention's effect】
[0040]
  According to the present invention, a part of the air pressurized by the centrifugal blower type mechanical supercharger is removed.Non-combustionIt can be bypassed to the exhaust pipe through a cylinder row that performs cycling. Thereby, the exhaust flow velocity in the exhaust pipe at the no-load rated rotation can be increased. Even when such a diesel engine is employed as a main engine such as an underwater work boat that discharges exhaust gas into water, it is possible to effectively prevent water from entering the exhaust pipe. Even if the head of the outlet of the exhaust pipe 14 becomes larger due to the influence of waves on the water surface, it is possible to obtain a large exhaust flow velocity by the piston action of the cylinder row regardless of the fluctuation of the depth pressure. .
[0041]
  Further, since the exhaust flow velocity can be increased by the above-described action, it is not necessary to reduce the inner diameter of the exhaust outlet throttle. Therefore, the back pressure generated in the exhaust pipe even when the exhaust gas temperature of the diesel engine becomes high and the volumetric flow rate of the exhaust gas increases during high load operation where all the compressed air from the turbocharger is used for combustion. Can be avoided, the upper limit of the output of the diesel engine can be increased, and the efficiency can be improved.
[Brief description of the drawings]
[0048]
FIG. 1 is a diagram schematically showing the structure of an underwater work boat equipped with a diesel engine according to an embodiment of the present invention.
FIG. 2 is a block diagram showing the diesel engine of FIG. 1 and its air supply mechanism.
FIG. 3 (a) is a plan view of a principal part showing an example of a switching device in the diesel engine of FIG. 1, and FIG. 3 (b) is a front view thereof.
4 is a graph showing an example of a piston stroke of the diesel engine of FIG. 1. FIG.
FIG. 5 is a graph showing the characteristics of a blower of a supercharger in the diesel engine of FIG. 1;
[Explanation of symbols]
[0049]
        1 engine
        2 Underwater work boat
        3 hull
        5 Exhaust outlet hardware
        7 Generator
        8 Propulsion device
      11 Engine body
      12 Air introduction pipe
      13 Intake pipe
      14 Exhaust pipe
      14a Upstream exhaust pipe
      14b Downstream exhaust pipe
      15 Output shaft
      16 Supercharger
      17 Input shaft
      18 Gear train
      19 Drive shaft
      20 Centrifugal blower
      21 Intake port
      22 Cooling device
      23 Exhaust port
      24 Exhaust outlet throttle
      25a, 25b Cylinder row
      26 switching device
      27 Control device
      28 Load sensor
      29 Rocker arm
      30a (Non-combustionCycle-actuated intake valve cam
      30b (Non-combustionCycle-operated exhaust intake valve cam
      31a Cam for intake valve (4 cycle operation)
      31b Exhaust valve cam (4 cycle operation)
      32 Camshaft
      33a Intake valve
      33b Exhaust valve

Claims (5)

A V-type 4-cycle diesel engine, which is applied to an underwater work boat and is supercharged with a centrifugal blower type mechanical supercharger,
A switching device for switching the valve timing of one cylinder row to four cycles and a non-combustion cycle in which only the intake stroke and the exhaust stroke are repeated ;
A control device for stopping fuel injection to the one cylinder row during the non-combustion cycle ;
An exhaust pipe for exhausting into the water, wherein the exhaust port of the one cylinder row and the exhaust port of the other cylinder row are connected together;
A turbocharged diesel engine configured such that air discharged from one of the cylinder rows and the exhaust gas from the other cylinder row in a non-combustion cycle are collectively discharged from the exhaust pipe . The diesel engine with a supercharger according to claim 1, wherein the valve timing of the one cylinder row is switched from a non-combustion cycle to four cycles when the load of the diesel engine is equal to or greater than a certain threshold value. Further comprising a load sensor for detecting a load of the diesel engine,
The diesel engine with a supercharger according to claim 1 or 2 , wherein the control device is configured to drive the switching device based on a load detected by a load sensor. The diesel engine with a supercharger according to claim 1, wherein a fixed throttle is disposed in the exhaust pipe. The switching device includes a cam mechanism for opening and closing the intake valve and the exhaust valve of the one cylinder row;
The cam mechanism includes a cam for four cycle timing, a cam for non-combustion cycle timing, and a cam shaft in which these cams are fixed in series.
The diesel engine with a supercharger according to claim 3, wherein the control device is configured to switch between a cam for four cycle timing and a cam for non-combustion cycle timing by moving the cam shaft in the axial direction thereof.

Images