CN111699309B - Fuel injection device - Google Patents

Abstract

In a fuel injection device according to an aspect of the present invention, a fuel injection valve is provided in a cylinder of a marine diesel engine. The fuel injection pump pressure-feeds fuel to the fuel injection valve through a pipe. The first water injection system injects water into a predetermined position of a fuel flow path from the fuel injection pump to an injection port of the fuel injection valve. The second water injection system injects water to a position on an upstream side of the fuel flow direction in the fuel flow path than the first water injection system. The control unit controls the water injection start times of the first water injection system and the second water injection system according to the engine load so that the water injection period of the first water injection system and the water injection period of the second water injection system overlap each other at least in part. The fuel injection valve injects fuel pumped by a fuel injection pump, water injected by a first water injection system, and water injected by a second water injection system from an injection port into a combustion chamber in a cylinder in layers.

Description

Fuel injection device

Technical Field

The present invention relates to a fuel injection device for a marine diesel engine mounted on a ship.

Background

In the field of ships, water injection technology for injecting fuel and water into a combustion chamber in a cylinder has been proposed as a method for reducing nitrogen oxides (NOx) in exhaust gas discharged from a marine diesel engine (see, for example, patent documents 1 to 4).

In the water injection techniques disclosed in patent documents 1 to 4, water is injected into a flow path of fuel pressure-fed from a fuel injection pump to a fuel injection valve, etc., and the fuel and the water are formed in a multilayer liquid column shape so that a plurality of fuel layers and water injection layers (layers of injected water) are alternately arranged in the flow path. The multi-layer liquid column-shaped fuel and water are injected from a fuel injection valve to a combustion chamber in a cylinder in layers in the order of arrangement of the plurality of fuel layers and water injection layers (for example, the order of fuel-water-fuel, etc.).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 6-123255

Patent document 2: japanese patent laid-open publication No. 6-257530

Patent document 3: japanese laid-open patent publication No. 4-175446

Patent document 4: japanese patent laid-open publication No. 5-288129

Problems to be solved by the invention

However, in the water injection technique in which the fuel and the water are injected in layers as described above, the amount of fuel in the fuel layer sandwiched between the water injection layers (hereinafter referred to as the amount of fuel between the water injection layers) in the flow path of the fuel is an extremely important factor from the viewpoint of ensuring stable performance of the marine diesel engine. That is, when the ratio of the amount of fuel between the water injection layers to the amount of fuel injected per one time (hereinafter, referred to as the fuel injection amount) of the fuel in the combustion chamber is excessively large or small, the marine diesel engine may cause combustion failure or the like, leading to deterioration of combustion efficiency or the like. In order to avoid such a situation, it is preferable that the fuel amount between the water injection zones can be adjusted so that the ratio of the fuel amount to the combustion injection amount is not too large or too small.

However, in the above-described conventional technique, since water is injected into one of the water injection layers on the downstream side (the injection port side of the fuel injection valve) and the upstream side (the fuel injection pump side) of the fuel layer and then the other water injection layer is injected, it is difficult to adjust the fuel amount between the water injection layers so that the ratio of the fuel amount to the fuel injection amount is not too large or too small. The fuel injection amount generally increases as the load on the marine diesel engine (hereinafter, appropriately referred to as the engine load) increases and decreases as the engine load decreases. Therefore, in the above-described conventional technology, at a certain engine load, although the fuel amount between the water injection layers may be an excessively large and small ratio to the fuel injection amount, at other engine loads, the ratio of the fuel amount between the water injection layers to the fuel injection amount is excessively large or small in many cases, and therefore, it is difficult to adjust the fuel amount between the water injection layers in accordance with the engine load.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel injection device capable of adjusting the amount of fuel between water injection layers in accordance with the engine load.

Means for solving the problems

In order to solve the above problems and achieve the object, a fuel injection device according to the present invention includes: a fuel injection valve provided in a cylinder of a marine diesel engine; a fuel injection pump that pressure-feeds fuel to the fuel injection valve through a pipe; a first water injection system that injects water from the fuel injection pump to a predetermined position of a fuel flow path that reaches an injection port of the fuel injection valve; a second water injection system flow path that injects water to a position on an upstream side of the fuel flow direction in the fuel flow path than the first water injection system; and a control unit that controls respective water injection start times of the first water injection system and the second water injection system so that a water injection period of the first water injection system and a water injection period of the second water injection system overlap each other at least in part according to a load of the marine diesel engine, wherein the fuel injection valve injects the fuel pumped by the fuel injection pump, the water injected by the first water injection system, and the water injected by the second water injection system from the injection port to a combustion chamber in the cylinder in a layer manner.

In the fuel injection device according to the present invention, the control unit controls the water injection start timing of each of the first water injection system and the second water injection system so that the amount of fuel between the water layer injected by the first water injection system and the water layer injected by the second water injection system is in a constant proportion to the injection amount of the fuel per one injection.

In the fuel injection device according to the present invention, the control unit calculates a standby time of the first water injection system from start of water injection by the second water injection system to start of water injection by the first water injection system based on a load of the marine diesel engine, and delays the water injection start time of the first water injection system from the water injection start time of the second water injection system by the calculated standby time.

In the fuel injection device according to the present invention, the control unit calculates a standby time of the second water injection system from start of water injection by the first water injection system to start of water injection by the second water injection system based on a load of the marine diesel engine, and delays the start time of water injection by the second water injection system from the start time of water injection by the calculated standby time.

In the fuel injection device according to the present invention, a ratio of a water injection amount of the first water injection system to a water injection amount of the second water injection system is constant.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the fuel amount in the water injection layer can be adjusted according to the engine load.

Drawings

Fig. 1 is a schematic diagram showing a configuration example of a marine diesel engine to which a fuel injection device according to a first embodiment of the present invention is applied.

Fig. 2 is a schematic diagram showing a configuration example of a fuel injection device according to a first embodiment of the present invention.

Fig. 3 is a diagram showing an example of the structure of the laminar liquid in the fuel flow path in the first embodiment of the present invention.

Fig. 4 is a diagram for explaining control of the water injection time in the first embodiment of the present invention.

Fig. 5 is a diagram for explaining the adjustment of the fuel amount between the water injection zones in the first embodiment of the present invention.

FIG. 6 is a diagram showing an example of the injection amount of the lamellar liquid according to the engine load in the first embodiment of the present invention

Fig. 7 is a schematic diagram showing a configuration example of a fuel injection device according to a second embodiment of the present invention.

Fig. 8 is a diagram for explaining control of the water injection time in the second embodiment of the present invention.

Fig. 9 is a diagram for explaining the adjustment of the fuel amount between the water injection zones in the second embodiment of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the fuel injection device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the present embodiment. Note that the drawings are schematic, and the dimensional relationship, the ratio, and the like of each element may be different from those in reality. The drawings may include portions having different dimensional relationships and ratios from each other. In the drawings, the same components are denoted by the same reference numerals.

(first embodiment)

First, a configuration of a marine diesel engine to which a fuel injection device according to a first embodiment of the present invention is applied will be described. Fig. 1 is a schematic diagram showing a configuration example of a marine diesel engine to which a fuel injection device according to a first embodiment of the present invention is applied. The marine diesel engine 10 is a propulsion engine (main engine) that rotates a propulsion propeller (neither shown) of a marine vessel via a propeller shaft. For example, the marine diesel engine 10 is a two-stroke diesel engine such as a uniflow-scavenging crosshead diesel engine.

As shown in fig. 1, a marine diesel engine 10 includes: a base 1 located below, a framework 5 provided on the base 1, and a cylinder liner (japanese: シリンダジャケット)11 provided on the framework 5. The base 1, the frame 5, and the cylinder liner 11 are fastened and fixed integrally by a plurality of tie bolts (fastening members) 21 and nuts 22 extending in the vertical direction. Further, the marine diesel engine 10 includes: a cylinder 12 provided in the cylinder liner 11, a piston 15 provided in the cylinder 12, and an output shaft (e.g., the crankshaft 2) that rotates in conjunction with the reciprocating motion of the piston 15.

The base 1 constitutes a crankcase of a marine diesel engine 10. As shown in fig. 1, a crankshaft 2 having a crank 4 and a bearing 3 are provided in a base 1. The crankshaft 2 is an example of an output shaft that outputs the propulsion force of the ship, and is rotatably supported by a bearing 3. The lower end of the connecting rod 6 is rotatably connected to the crankshaft 2 via a crank 4.

As shown in fig. 1, the frame 5 is provided with a link 6, a guide plate 7, and a crosshead 8. The frame 5 is arranged such that a pair of guide plates 7 provided along the axial direction of the piston is formed at a distance in the width direction. The connecting rod 6 is disposed between the pair of guide plates 7 so that a lower end portion thereof is connected to the crankshaft 2. A crosshead pin 9 connected to a lower end portion of the piston rod 16 and a crosshead bearing (not shown) connected to an upper end portion of the connecting rod 6 are rotatably connected to the crosshead 8 at a lower half portion of the crosshead pin 9. As shown in fig. 1, the crosshead 8 is disposed between the pair of guide plates 7 and is supported to be movable along the pair of guide plates 7.

As shown in fig. 1, a cylinder liner 11 is provided at an upper portion of the frame 5, and supports a cylinder 12. The cylinder 12 is a tubular structure (cylinder) composed of a cylinder liner 13 and a cylinder head 14, and has a combustion chamber 17 for combusting fuel. The cylinder liner 13 is, for example, a cylindrical structure, and is disposed in the cylinder liner 11. A cylinder head 14 is fixed to an upper portion of the cylinder liner 13, thereby defining a space (a combustion chamber 17, etc.) in the cylinder liner 13. In the space portion of the cylinder liner 13, a piston 15 is provided to be capable of reciprocating in a piston axial direction (vertical direction in fig. 1). As shown in fig. 1, an upper end portion of a piston rod 16 is connected to a lower end portion of the piston 15.

Further, as shown in fig. 1, an exhaust valve 18 and a valve device 19 are provided in the cylinder head 14. The exhaust valve 18 is a valve that openably closes an exhaust port (exhaust hole) of an exhaust pipe 20, and the exhaust pipe 20 communicates with the combustion chamber 17 in the cylinder 12. The valve device 19 is a device that drives the exhaust valve 18 to open and close. The combustion chamber 17 is a space surrounded by the exhaust valve 18, the cylinder liner 13, the cylinder head 14, and the piston 15.

As shown in fig. 1, the marine diesel engine 10 includes a fuel injection valve 30, a fuel injection pump 41, a first water injection pump 51, and a second water injection pump 61. The combustion injection valve 30 is provided in the cylinder 12 (e.g., the cylinder head 14) such that an injection port is directed into the combustion chamber 17. As shown in fig. 1, the combustion injection pump 41, the first water injection pump 51, and the second water injection pump 61 are provided in the vicinity of the cylinder 12. Although not shown in fig. 1, the fuel injection pump 41, the first water injection pump 51, and the second water injection pump 61 are connected to the fuel injection valve 30 so as to be able to communicate with each other via a pipe or the like. The fuel injection pump 41 appropriately pressure-feeds fuel to the fuel injection valve 30 through a flow path formed by a pipe or the like. The first water injection pump 51 and the second water injection pump 61 appropriately inject water such as distilled water into the flow path of the fuel pressure-fed by the fuel injection pump 41. For example, the water injection position of the first water injection pump 51 is located downstream of the water injection position of the second water injection pump 61 in the flow path of the fuel. The fuel injection valve 30 alternately injects (i.e., injects in layers) the fuel pressure-fed by the fuel injection valve 41, the water injected by the first water injection pump 51, and the water injected by the second water injection pump 61 into the combustion chamber 17 by the pressure-feeding action of the fuel injection valve 41.

In the marine diesel engine 10 having the above-described configuration, fuel and water are supplied from the fuel injection valve 30 to the combustion chamber 17 in the cylinder 12, and combustion gas such as compressed air is supplied through scavenging holes (not shown). In the combustion chamber 17, the supplied fuel is combusted by the combustion gas, and the combustion temperature of the fuel is lowered by the supplied water to reduce the amount of NOx discharged. Further, the piston 15 reciprocates in the piston axial direction within the cylinder 12 by energy generated by combustion of fuel in the combustion chamber 17. At this time, when the exhaust valve 18 is operated by the valve operating device 19 to open the cylinder 12, exhaust gas generated by combustion of fuel is pushed out to the exhaust pipe 20. On the other hand, the combustion gas is reintroduced into the cylinder 12 from the scavenging port.

When the piston 15 reciprocates in the piston axial direction as described above, the piston rod 16 reciprocates in the piston axial direction together with the piston 15. Accompanying this, the crosshead 8 reciprocates in the piston axial direction along the guide plate 7. Thereby, the crosshead pin 9 of the crosshead 8 applies a rotational driving force to the connecting rod 6 via the crosshead bearing. The crank 4 connected to the lower end of the connecting rod 6 is cranked (rotated) by the rotational driving force, and as a result, the crankshaft 2 is rotated. The crankshaft 2 converts the reciprocating motion of the piston 15 into a rotational motion in this manner, and rotates the propeller for propelling the ship together with the propeller shaft, thereby outputting the propulsive force of the ship.

Next, the structure of the fuel injection device according to the first embodiment of the present invention will be described. Fig. 2 is a schematic diagram showing a configuration example of a fuel injection device according to a first embodiment of the present invention. As shown in fig. 2, the fuel injection device 100 includes a plurality of (three in the first embodiment) fuel injection valves 30, a fuel pressure feed system 40, a downstream side water injection system 50, and an upstream side water injection system 60. The fuel injection device 100 includes a water supply pump 71, a water supply pipe 72, check valves 73a and 73b, an accumulator 81, a high-pressure pump 82, a detector 91, and a controller 92. In fig. 2, solid arrows indicate the flow of fluid such as fuel or water, and broken arrows indicate electrical signal lines.

The plurality of fuel injection valves 30 are injection valves for injecting fuel and water in layers into the combustion chamber 17 (see fig. 1) in the cylinder 12 of the marine diesel engine 10. These fuel injection valves 30 are provided in a plurality of cylinders 12 (only one is shown in fig. 1) of the marine diesel engine 10. Hereinafter, the configuration of the fuel injection valve 30 and the like will be described by exemplifying one of the plurality of fuel injection valves 30. These fuel injection valves 30 are configured to be identical to each other.

As shown in fig. 2, the fuel injection valve 30 and a fuel injection pump 41 of the fuel pressure feed system 40 are communicably connected via a pipe or the like. The fuel injection valve 30 is connected to the downstream side water injection system 50 and the upstream side water injection system 60 so as to be able to communicate with each other via a pipe or the like. The fuel injection valve 30 injects fuel pressure-fed by the fuel injection pump 41, water injected by the downstream side water injection system 50, and water injected by the upstream side water injection system 60 from the injection port 31 into the combustion chamber 17 in the cylinder 12 in layers.

Specifically, as shown in fig. 2, the fuel injection valve 30 includes: an injection port 31, internal flow paths 32, 33 communicating with the injection port 31, and check valves 34a, 34 b. One of the internal flow paths 32 is a flow path through which the fuel and water to be injected flow. One end of the internal flow path 32 is connected to the injection port 31 of the fuel injection valve 30, and the other end thereof is connected to the fuel injection pipe 42 (for example, a branch pipe 42a thereof). The pipe of the upstream water injection system 60 (for example, the branch pipe 62a of the upstream water injection pipe 62) is connected to a position upstream of the internal flow path 32 (the second water injection position P2 upstream of the first water injection position P1 in the first embodiment) via the check valve 34 a. The other internal flow path 33 is a flow path for passing water injected into the internal flow path 32. One end of the internal flow path 33 is connected to a position (the first water injection position P1 in the first embodiment) near the injection port 31 of the internal flow path 32, and the other end thereof is connected to a pipe of the downstream water injection system 50 (for example, the branch pipe 52a of the downstream water injection pipe 52).

The check valve 34a allows water to flow from the upstream side water injection system 60 to the internal flow path 32 of the fuel injection valve 30, and prevents reverse flow thereof. The check valve 34b is provided in the middle of the internal flow path 33. The check valve 34b allows water to flow from the downstream side water injection system 50 to the internal flow path 32 through the internal flow path 33 of the fuel injection valve 30, and prevents reverse flow thereof.

The fuel pressure-feed system 40 is a device for pressure-feeding fuel to the fuel injection valves 30. As shown in fig. 2, the fuel pressure-feed system 40 includes a fuel injection pump 41, a fuel injection pipe 42, and a control valve 45.

The fuel injection pump 41 is a hydraulically driven pump that performs pressure feeding of fuel using the pressure of the hydraulic oil. Specifically, the fuel injection pump 41 receives fuel from a fuel tank (not shown) through piping or the like. The fuel injection pump 41 pressure-feeds the received fuel to the fuel injection valve 30 through the fuel injection pipe 42. The pressure-feeding action of the fuel injection pump 41 causes the fuel injection valve 30 to perform stratified injection of the fuel and water from the injection port 31 into the combustion chamber 17 in the cylinder 12.

The fuel injection pipe 42 is a pipe for passing fuel between the fuel injection pump 41 and the fuel injection valve 30. For example, as shown in fig. 2, one end of the fuel injection pipe 42 is connected to a discharge port of the fuel injection pump 41. Further, a branch portion 43 is provided at a middle portion of the fuel injection pipe 42. The fuel injection pipe 42 branches from the branch portion 43 toward the other end portion into a plurality of branch pipes (three branch pipes 42a, 42b, and 42c in the first embodiment). For example, as shown in fig. 2, a branch pipe 42a of the branch pipes 42a, 42b, and 42c of the fuel injection pipe 42 is connected to the internal flow path 32 of one fuel injection valve 30. The fuel injection pipe 42 communicates the fuel injection valve 30 and the fuel injection pump 41 via a branch pipe 42 a. Similarly, the remaining branch pipes 42b and 42c are connected to the other fuel injection valves 30, respectively.

The control valve 45 is a valve for controlling the supply of the hydraulic oil from the pressure accumulating portion 81 to the fuel injection pump 41. Specifically, as shown in fig. 2, the control valve 45 is formed of an electrically operated on-off valve such as an electromagnetic valve, and although not shown, the control valve 45 is provided so as to be able to communicate the fuel injection pump 41 and the pressure accumulation portion 81 by opening and closing a logic valve driven by the control valve 45. The control valve 45 is opened at the fuel injection time, and supplies the working oil in the pressure accumulating portion 81 to the fuel injection pump 41. The fuel injection pump 41 pressure-feeds the fuel to the fuel injection valve 30 by the pressure of the supplied hydraulic oil. On the other hand, the control valve 45 is closed at a time other than the fuel injection time, and the supply of the working oil from the pressure accumulator 81 to the fuel injection pump 41 is stopped. The timing of the opening and closing drive of the control valve 45 is controlled by the control unit 92.

The downstream water injection system 50 is an example of a first water injection system that injects water to the first water injection position P1 of the fuel flow path in the first embodiment. As shown in fig. 2, the downstream water injection system 50 includes a first water injection pump 51, a downstream water injection pipe 52, a check valve 54, and a control valve 55.

The first water injection pump 51 is a hydraulically driven pump that injects water using the pressure of the hydraulic oil. Specifically, the first water injection pump 51 receives water from the water supply pump 71 through a water supply pipe 72 and the like. The first water injection pump 51 pressure-feeds the received water to the internal flow path 32 of the fuel injection valve 30 through the downstream water injection pipe 52 and the internal flow path 33 of the fuel injection valve 30. Thus, the first water injection pump 51 injects water to the first water injection position P1 of the fuel flow path in the first embodiment.

The downstream water injection pipe 52 is a pipe for allowing water injected by the first water injection pump 51 to flow to the first water injection position P1 of the fuel flow path. For example, as shown in fig. 2, one end of the downstream water injection pipe 52 is connected to the discharge port of the first water injection pump 51. A branch portion 53 is provided at a middle portion of the downstream side water injection pipe 52. The downstream water injection pipe 52 branches from the branch portion 53 to the other end portion into a plurality of branch pipes (three branch pipes 52a, 52b, and 52c in the first embodiment). For example, as shown in fig. 2, the branch pipe 52a of the branch pipes 52a, 52b, and 52c of the downstream water injection pipe 52 is connected to the internal flow path 33 of one fuel injection valve 30. The downstream water injection pipe 52 communicates the internal flow path 33 of the fuel injection valve 30 with the first water injection pump 51 via a branch pipe 52 a. Similarly, the remaining branch pipes 52b and 52c are connected to the other fuel injection valves 30, respectively.

The check valve 54 is a valve for limiting the flow direction of water in the downstream-side water injection pipe 52 to one direction and preventing the reverse flow of water. As shown in fig. 2, the check valve 54 is provided at a middle portion of the downstream-side water injection pipe 52 (for example, a portion between the first water injection pump 51 and the branch portion 53). The check valve 54 allows water to flow from the first water injection pump 51 side to the fuel flow path side (the internal flow paths 32 and 33 side of the fuel injection valve 30 in the first embodiment) and prevents reverse flow thereof.

The control valve 55 is a valve for controlling the supply of the hydraulic oil from the pressure accumulating portion 81 to the first water injection pump 51. Specifically, the control valve 55 is constituted by an electrically operated on-off valve such as an electromagnetic valve, and as shown in fig. 2, the control valve 55 is provided so as to be able to communicate the first water injection pump 51 with the pressure accumulating portion 81. The control valve 55 is opened during the period in which water is injected from the first water injection pump 51 into the fuel flow path (hereinafter, referred to as the water injection period of the downstream side water injection system 50 as appropriate), and the hydraulic oil in the pressure accumulating portion 81 is supplied to the first water injection pump 51. The first water injection pump 51 pressure-feeds and injects water to the first water injection position P1 of the fuel flow path by the pressure of the supplied hydraulic oil. On the other hand, the control valve 55 is closed at a time other than the water injection period of the downstream side water injection system 50, and the supply of the hydraulic oil from the pressure accumulator 81 to the first water injection pump 51 is stopped. The timing of the opening and closing operation of the control valve 55 is controlled by the control unit 92.

The upstream water injection system 60 is an example of a second water injection system for injecting water to the second water injection position P2 of the fuel flow path in the first embodiment. As shown in fig. 2, the upstream side water injection system 60 includes a second water injection pump 61, an upstream side water injection pipe 62, a check valve 64, and a control valve 65.

The second water injection pump 61 is a hydraulically driven pump that injects water using the pressure of the hydraulic oil. Specifically, the second water injection pump 61 receives water from the water supply pump 71 through the water supply pipe 72 and the like. The second water injection pump 61 pressure-feeds the received water to the internal flow path 32 of the fuel injection valve 30 through the upstream side water injection pipe 62. Thereby, the second water injection pump 61 injects water to the second water injection position P2 of the fuel flow path in the first embodiment.

The upstream water injection pipe 62 is a pipe for circulating the water injected by the second water injection pump 61 to the second water injection position P2 of the fuel flow path. For example, as shown in fig. 2, one end of the upstream side water injection pipe 62 is connected to the discharge port of the second water injection pump 61. Further, a branch portion 63 is provided at a middle portion of the upstream side water injection pipe 62. The upstream-side water injection pipe 62 branches from the branch portion 63 to the other end portion into a plurality of branch pipes (three branch pipes 62a, 62b, and 62c in the first embodiment). For example, as shown in fig. 2, a branch pipe 62a of the branch pipes 62a, 62b, and 62c of the upstream-side water injection pipe 62 is connected to the internal flow path 32 of one fuel injection valve 30 via a check valve 34 a. The upstream-side water injection pipe 62 communicates the internal flow path 32 of the fuel injection valve 30 with the second water injection pump 61 via a branch pipe 62 a. Similarly, the remaining branch pipes 62b and 62c are connected to the respective other fuel injection valves 30.

The check valve 64 is a valve for restricting the flow direction of water in the upstream side water injection pipe 62 to one direction and preventing the reverse flow of water. As shown in fig. 2, the check valve 64 is provided in a middle portion of the upstream water injection pipe 62 (for example, a portion between the second water injection pump 61 and the branch portion 63). The check valve 64 allows water to flow from the second water injection pump 61 side to the fuel flow path side (the internal flow path 32 side of the fuel injection valve 30 in the present first embodiment) and prevents reverse flow thereof.

The control valve 65 is a valve for controlling the supply of the hydraulic oil from the pressure accumulating portion 81 to the second water injection pump 61. Specifically, the control valve 65 is constituted by an electrically operated on-off valve such as an electromagnetic valve, and is provided so as to be able to communicate between the second water injection pump 61 and the pressure accumulating portion 81, as shown in fig. 2. The control valve 65 is opened when water from the second water injection pump 61 is injected into the fuel flow path (hereinafter, appropriately referred to as a water injection period of the upstream side water injection system 60), and supplies the hydraulic oil in the pressure accumulating portion 81 to the second water injection pump 61. The second water injection pump 61 pressure-feeds and injects water to the second water injection position P2 of the fuel flow path by the pressure of the supplied hydraulic oil. On the other hand, the control valve 65 is closed at a time other than the water injection period of the upstream side water injection system 60, and the supply of the hydraulic oil from the pressure accumulator 81 to the second water injection pump 61 is stopped. The timing of the opening and closing drive of the control valve 65 is controlled by the control unit 92.

Here, the fuel flow path in the first embodiment is a flow path of fuel from the fuel injection pump 41 to the injection port 31 of the fuel injection valve 30. For example, the fuel flow path is formed by the fuel injection pipe 42 including the branch pipes 42a to 42c and the like and the internal flow path 32 of the fuel injection valve 30. The first water injection position P1 is a position defined in the fuel circulation path. In the first embodiment, for example, as shown in fig. 2, the first water filling position P1 is located at a position in the internal flow path 32 of the fuel injection valve 30 near the injection port 31, that is, at a position in the fuel flow path where a predetermined amount of fuel (fuel in the first fuel layer F1 shown in fig. 3 described later) present at the most downstream side in the fuel flow direction is located at the most upstream side. The second water injection position P2 is located on the upstream side in the fuel flow direction in the fuel flow path compared to the downstream side water injection system 50. In the first embodiment, for example, as shown in fig. 2, the second water filling position P2 is located on the fuel injection pump 41 side in the internal flow path 32 of the fuel injection valve 30, that is, on the upstream side in the fuel flow direction from the first water filling position P1. In the first embodiment, the fuel flows in a direction from the fuel injection pump 41 toward the injection port 31 of the fuel injection valve 30 through the fuel injection pipe 42 and the like.

The water supply pump 71 is a pump for supplying the water injected into the fuel flow path to the first and second water injection pumps 51 and 61. As shown in fig. 2, the water supply pump 71 is connected to the first and second water injection pumps 51 and 61 so as to be able to flow through a water supply pipe 72 and the like. One end of the water supply pipe 72 is connected to the water supply pump 71. The water supply pipe 72 branches into branch pipes 72a and 72b at a midway portion thereof. One branch pipe 72a of the water supply pipe 72 is connected to the first water injection pump 51 via a check valve 73 a. The other branch pipe 72b of the water supply pipe 72 is connected to the second water injection pump 61 via a check valve 73 b. The water supply pump 71 supplies water stored in a water supply tank (not shown) to the first water injection pump 51 through a branch pipe 72a of the water supply pipe 72 and the like, and to the second water injection pump 61 through a branch pipe 72b of the water supply pipe 72 and the like. The check valve 73a allows water to flow from the water supply pump 71 side to the first water injection pump 51 side, and prevents reverse flow thereof. The check valve 73b allows water to flow from the water supply pump 71 side to the second water filling pump 61 side, and prevents reverse flow thereof.

The pressure accumulating unit 81 accumulates the pressure of the hydraulic oil that operates the fuel pressure feed system 40, the downstream side water injection system 50, and the upstream side water injection system 60, respectively. The pressure accumulating portion 81 is a hollow structure in which a pressure accumulating chamber capable of storing the hydraulic oil is formed, and is connected to the high-pressure pump 82 through a pipe or the like so as to be able to communicate therewith, as shown in fig. 2. The pressure accumulating portion 81 accumulates the hydraulic oil discharged (pressure-fed) from the high-pressure pump 82 in an internal pressure accumulating chamber, thereby accumulating the pressure of the hydraulic oil. The pressure of the hydraulic oil accumulated in the pressure accumulating portion 81 is adjusted by the discharge amount of the hydraulic oil from the high-pressure pump 82 to the pressure accumulating portion 81. The pressure of the hydraulic oil accumulated in the pressure accumulator 81 is commonly used for the operation of the fuel injection pump 41 of the fuel pressure-feed system 40, the operation of the first water injection pump 51 of the downstream-side water injection system 50, and the operation of the second water injection pump 61 of the upstream-side water injection system 60.

The detection unit 91 detects the crank angle of the marine diesel engine 10 (see fig. 1). In the first embodiment, the detection unit 91 detects the rotation angle (i.e., the crank angle) of the crank 4, and the crank 4 rotates in accordance with one cycle of reciprocation of the piston 15 in the cylinder 12. At this time, the detection unit 91 detects the rotation angle of the crank 4 with respect to the reference state as the crank angle. The reference state of the crank 4 may be, for example, a state of the crank 4 when the piston 15 is at the bottom dead center or the top dead center. The detection unit 91 detects the crank angle with the passage of time, and sends an electric signal indicating the detected crank angle to the control unit 92 each time.

The controller 92 controls the laminar injection timing of the fuel and water, the water injection timing of the downstream water injection system 50, and the water injection timing of the upstream water injection system 60. In the first embodiment, the stratified injection time of the fuel and the water is a time when the fuel and the water are injected from the fuel injection valve 30 in layers into the combustion chamber 17 (see fig. 1) in the cylinder 12 of the marine diesel engine 10. The water injection time of the downstream water injection system 50 is a water injection start time at which water injection to the first water injection position P1 of the fuel circulation path is started by the first water injection pump 51, and a water injection end time at which water injection to the first water injection position P1 is ended. The water injection time of the upstream water injection system 60 is a water injection start time at which water injection to the second water injection position P2 of the fuel flow path is started by the second water injection pump 61, and a water injection end time at which water injection to the second water injection position P2 is ended.

Specifically, the control unit 92 is configured by a CPU, a memory, a program device, and the like for executing various programs. The control unit 92 receives an electric signal from the detection unit 91, and controls the opening and closing drive of the control valve 45 of the fuel pressure-feed system 40 so that the control valve is opened when the crank angle indicated by the received electric signal is a predetermined rotation angle. The control unit 92 controls the opening/closing drive of the control valve 45 to control the operation time of the fuel injection pump 41. Thus, the controller 92 controls the stratified charge injection time of the fuel and water from the fuel injection valve 30 into the combustion chamber 17.

In the stratified injection time, the following substances are injected from the fuel injection valve 30 into the combustion chamber 17 in layers by the pressure-feed action of the fuel injection pump 41: of the fuel pressure-fed to the fuel flow path by the fuel injection pump 41, a necessary amount of fuel according to the engine load, water injected into the first water injection position P1 of the fuel flow path by the first water injection pump 51, and water injected into the second water injection position P2 of the fuel flow path by the second water injection pump 61. Then, the fuel flow path (the fuel flow path constituted by the fuel injection pipe 42 and the internal flow path 32 of the fuel injection valve 30 in the first embodiment) is filled with the remaining fuel that is not injected.

The controller 92 controls the water injection time of the downstream water injection system 50 and the water injection time of the upstream water injection system 60 so that water is injected into each of the first water injection position P1 and the second water injection position P2 of the fuel flow path filled with fuel at a time other than the above-described laminar injection time of fuel and water. At this time, the control unit 92 controls the water injection start time of the first water injection pump 51 of the downstream side water injection system 50 and the water injection start time of the second water injection pump 61 of the upstream side water injection system 60 so that the water injection period of the downstream side water injection system 50 and the water injection period of the upstream side water injection system 60 overlap each other at least partially in accordance with the engine load of the marine diesel engine 10.

In the first embodiment, by injecting water into each of the first water injection position P1 and the second water injection position P2 of the fuel flow path in a state filled with fuel, a layered liquid composed of each layer of the fuel and the water is formed in the fuel flow path. Fig. 3 is a diagram showing an example of the structure of the laminar liquid in the fuel flow path in the first embodiment of the present invention. In fig. 3, the injection port side is the injection port 31 side of the fuel injection valve 30, that is, the downstream side in the fuel flow direction in the fuel flow path. The fuel injection pump side is the fuel injection pump 41 side of the fuel pressure-feed system 40, that is, the upstream side in the fuel flow direction in the fuel flow path. As shown in fig. 3, the laminar liquid 200 is a plurality of liquid layers arranged from the injection port side toward the fuel injection pump side, and is composed of, for example, a first liquid layer L1, a second liquid layer L2, a third liquid layer L3, a fourth liquid layer L4, and a fifth liquid layer L5.

The first liquid layer L1 is the most downstream liquid layer in the layered liquid 200. The layered liquid 200 comprises the first fuel layer F1 as the first liquid layer L1. The first fuel bed F1 is the first fuel bed from the injection port side among the plurality (three in fig. 3) of fuel beds contained in the laminar liquid 200, and is composed of a predetermined amount of fuel present at the most downstream in the flow direction of the fuel.

The second liquid layer L2 is the liquid layer closest to the upstream of the liquid layer L1 in the layered liquid 200. The layered liquid 200 includes the first water-injected layer W1 as the second liquid layer L2. The first water-pouring layer W1 is the first water-pouring layer from the ejection port side among the plurality (two in fig. 3) of water-pouring layers included in the layered liquid 200. The first water injection layer W1 is formed by injecting a necessary amount of water from the first water injection pump 51 to the first water injection position P1 of the fuel flow path.

The third liquid layer L3 is the liquid layer closest to the upstream of the second liquid layer L2 in the layered liquid 200. The layered liquid 200 contains the second fuel layer F2 as the third liquid layer L3. The second fuel layer F2 is the second fuel layer counted from the injection port side among the plurality of fuel layers contained in the layered liquid 200. The second fuel layer F2 is composed of fuel sandwiched between a layer of water injected into the first water injection position P1 and a layer of water injected into the second water injection position P2 of the fuel flow path.

The fourth liquid layer L4 is the liquid layer closest to the upstream of the third liquid layer L3 in the layered liquid 200. The layered liquid 200 contains a second water-injected layer W2 as the fourth liquid layer L4. The second water-injection layer W2 is the second water-injection layer counted from the ejection port side among the plurality of water-injection layers included in the layered liquid 200. The second water injection layer W2 is formed by injecting a necessary amount of water from the second water injection pump 61 to the second water injection position P2 of the fuel flow path.

The fifth liquid layer L5 is the most upstream liquid layer in the layered liquid 200. The layered liquid 200 contains the third fuel layer F3 as the fifth liquid layer L5. The third fuel layer F3 is the third fuel layer from the injection port side among the plurality of fuel layers contained in the layered liquid 200. The third fuel layer F3 is composed of the fuel present closest upstream of the second water-injected layer W2.

Such a lamellar liquid 200 of fuel and water is injected from the injection port 31 of the fuel injection valve 30 into the combustion chamber 17 in the cylinder 12 at the time of one cycle of reciprocation of the piston 15. At this time, the injection amount per one time to the combustion chamber 17, that is, the fuel injection amount Qfa of the stratified liquid 200 is represented by the sum of the fuel amount Qf1 of the first fuel layer F1, the fuel amount Qf2 of the second fuel layer F2, and the fuel amount Qf3 of the third fuel layer F3 (which is Qf1+ Qf2+ Qf 3). The fuel injection amount Qfa of the stratified liquid 200 increases as the engine load increases, and decreases as it decreases.

The amount of fuel between the water injection layers (the amount of fuel Qf2 in the second fuel layer F2 sandwiched between the first water injection layer W1 and the second water injection layer W2 in the first embodiment) in the layered liquid 200 is adjusted by controlling the respective water injection start times of the downstream water injection system 50 and the upstream water injection system 60. In this case, the amount of fuel between the injection zones (Qf 2) is preferably adjusted to be a constant ratio with respect to the fuel injection amount Qfa corresponding to the engine load.

On the other hand, the water injection amount in the primary fuel injection into the combustion chamber 17, that is, the water injection amount Qwa of the layered liquid 200 is represented by the sum of the water injection amount Qw1 in the first water injection layer W1 and the water injection amount Qw2 in the second water injection layer W2 (Qw 1+ Qw 2). The water injection amount Qwa of the lamellar liquid 200 is adjusted to a necessary amount according to the engine load, so that NOx reduction and combustion efficiency improvement are achieved. At this time, the ratio of the water injection amount Qw1 of the first water injection layer W1 to the water injection amount Qw2 of the second water injection layer W2, that is, the ratio of the water injection amount of the downstream side water injection system 50 to the water injection amount of the upstream side water injection system 60 is preferably constant.

Next, control of the water injection time for adjusting the amount of fuel between the water injection zones in the first embodiment of the present invention will be described. Fig. 4 is a diagram for explaining control of the water injection time in the first embodiment of the present invention. In fig. 4, the valve control signal S1 is a control signal for instructing the control valve 55 of the first water injection pump 51 to open and close, and the first water injection pump 51 injects water to the first water injection position P1 (see fig. 2) of the fuel flow path. The valve control signal S2 is a control signal for instructing the open/close driving of the control valve 65 of the second water injection pump 61, and the second water injection pump 61 injects water to the second water injection position P2 (see fig. 2) of the fuel flow path. Fig. 5 is a diagram for explaining the adjustment of the fuel amount between the water injection layers in the first embodiment of the present invention. In fig. 5, the fuel column 201 is a columnar fuel remaining in the fuel flow path in the first embodiment.

In the first embodiment, the controller 92 transmits valve control signals S1 and S2 shown in fig. 4 to the control valves 55 and 65, respectively, to control the timing of opening and closing the control valves 55 and 65, respectively. Thus, the controller 92 controls the water injection time (first stage water injection time) of the downstream side water injection system 50 and the water injection time (second stage water injection time) of the upstream side water injection system 60 so that at least a part of the water injection period of the downstream side water injection system 50 and the water injection period of the upstream side water injection system 60 overlap each other in accordance with the engine load. In this case, the controller 92 preferably controls the water injection start timing of each of the downstream side water injection system 50 and the upstream side water injection system 60 so that the amount of fuel between the layer of water injected by the downstream side water injection system 50 and the layer of water injected by the upstream side water injection system 60 is in a constant ratio to the fuel injection amount Qfa corresponding to the engine load.

More specifically, the control unit 92 calculates the standby time Δ T for water injection in accordance with the engine load. The standby time Δ T is a time from the operation start time of the water filling piston of the water filling system that first starts water filling to the operation start time of the water filling piston of the water filling system that subsequently starts water filling in the downstream side water filling system 50 and the upstream side water filling system 60. The standby time Δ T is expressed by, for example, a function f (x, y, z) including independent variables x, y, z, where the engine speed (engine speed per unit time) at the time of the engine load required by the marine diesel engine 10 according to the ship's sailing condition is x, the fuel injection amount (injection amount per time of fuel) is y, and the water injection amount (amount of water injected into the fuel by one injection) is z, as shown in the following equation (1). For example, the control unit 92 calculates the standby time Δ T such that the standby time Δ T increases with an increase in the engine load and the standby time Δ T decreases with a decrease in the engine load.

Standby time Δ T ═ f (x, y, z) … (1)

The engine speed, the fuel injection amount, and the water injection amount can be derived based on the results of simulation, experiment, and the like of the marine diesel engine 10. This equation (1) is preset in the control unit 92.

The controller 92 calculates the standby time Δ T1 of the downstream side water injection system 50 as the standby time Δ T. The standby time Δ T1 of the downstream side water injection system 50 is the time from the start of water injection by the upstream side water injection system 60 to the start of water injection by the downstream side water injection system 50, that is, the time from the start of operation of the second water injection pump 61 to the start of operation of the first water injection pump 51. The controller 92 delays the water injection start time of the downstream side water injection system 50 from the water injection start time of the upstream side water injection system 60 by the calculated standby time Δ T1.

Specifically, the control unit 92 acquires the crank angle indicated by the electric signal received from the detection unit 91 as the crank angle detected by the detection unit 91 (hereinafter, appropriately referred to as a crank angle detection value). As shown in fig. 4, the controller 92 instructs the control valve 65 of the upstream water injection system 60 to open and drive at time T1 when the detected crank angle value becomes the crank angle R1. Thereby, the controller 92 starts the operation of the second water injection pump 61 of the upstream side water injection system 60. According to this control, the second water injection pump 61 starts water injection to the second water injection position P2 of the fuel circulation path. That is, the time T1 of the crank angle R1 is the water injection start time of the upstream side water injection system 60. As shown in fig. 5, at this time T1, the injection of water 202 into the fuel column 201 in the fuel flow path starts at the second water injection position P2.

As shown in fig. 5, at time T0, the water injection into the fuel column 201 is not started during the period from the end of the previous fuel injection to the water injection start time (time T1). The fuel amount of the fuel column 201 at this time corresponds to the fuel injection amount Qfa described above.

Next, the controller 92 starts the water injection of the downstream side water injection system 50 at a time delayed from the water injection start time of the upstream side water injection system 60 by the standby time Δ T1 calculated as described above. Specifically, the control unit 92 converts the standby time Δ T1 of the downstream water injection system 50 into the change amount Δ R of the crank angle based on the engine speed corresponding to the engine load and the elapsed time of the engine rotation. The controller 92 calculates the crank angle R2 by adding the obtained change amount Δ R of the crank angle to the crank angle R1 at the water injection start time (time T1) of the upstream side water injection system 60. As shown in fig. 4, the control unit 92 instructs the control valve 55 of the downstream water injection system 50 to open and drive at a time T2 when the detected crank angle value reaches the crank angle R2. Thereby, the controller 92 continues the operation of the second water injection pump 61 of the upstream water injection system 60 and starts the operation of the first water injection pump 51 of the downstream water injection system 50. According to this control, the first water injection pump 51 starts water injection to the first water injection position P1 of the fuel circulation path. That is, time T2 of the crank angle R2 is the water injection start time of the downstream water injection system 50. On the other hand, the second water injection pump 61 continues to inject water to the second water injection position P2 of the fuel circulation path. As shown in fig. 5, at this time T2, the injection of water 202 to the second water injection position P2 in the fuel column 201 within the fuel flow path is continued, and the injection of water 203 to the first water injection position P1 is started.

Thereafter, the second water injection pump 61 continues to inject water to the second water injection position P2 of the fuel flow path until the control valve 65 is driven to close. At the same time, the first water injection pump 51 continues to inject water to the first water injection position P1 of the fuel flow path until the control valve 55 is driven to close.

For example, as shown in fig. 4 and 5, during a time Δ T2 from a crank angle R2 to a crank angle R3(> R2), the injection of the water 202 to the second water injection position P2 is performed, and the injection of the water 203 to the first water injection position P1 is performed. With the injection of the water 203 at the first water injection position P1, the fuel between the first water injection position P1 and the second water injection position P2 is pushed back toward the upstream side in the flow direction beyond the water 202 at the second water injection position P2. Thereby, the amount of fuel between the first water filling position P1 and the second water filling position P2 is adjusted in a decreasing manner.

Next, at time T3 of the crank angle R3, the water 202 at the second water injection position P2 is injected to extend over the entire width of the fuel column 201 (the width of the fuel flow path). At this time, as shown in fig. 5, the water 202 of the second water injection position P2 divides the fuel column 201 into the downstream-side fuel 201a located on the downstream side of the second water injection position P2 and the most upstream fuel 201b located on the upstream side of the second water injection position P2. At this stage, even if the water 203 is injected at the first water injection position P1, the fuel between the first water injection position P1 and the second water injection position P2 is not pushed back to the upstream side in the flow direction beyond the water 202 at the second water injection position P2. Thereby, the adjustment of the fuel amount between the first water filling position P1 and the second water filling position P2 is ended and the fuel amount of the downstream side fuel 201a is decided.

Thereafter, as shown in fig. 4, the controller 92 instructs the control valve 65 of the upstream side water injection system 60 to close at time T4 when the calculated crank angle value becomes the crank angle R4. Thereby, the controller 92 continues the operation of the first water injection pump 51 of the downstream side water injection system 50 and stops the operation of the second water injection pump 61 of the upstream side water injection system 60. According to this control, the second water injection pump 61 ends the water injection to the second water injection position P2 of the fuel circulation path. That is, the time T4 of the crank angle R4 is the water injection completion time of the upstream side water injection system 60. On the other hand, the first water injection pump 51 continues the water injection to the first water injection position P1 of the fuel circulation path.

For example, as shown in fig. 4 and 5, during the time Δ T3 from the crank angle R3 to the crank angle R4(> R3), the water 202 of the second water injection position P2 is further injected from a state that extends over the entire width direction of the fuel column 201, and the injection of the water 203 to the first water injection position P1 is continued. At this stage, the injection of the water 203 at the first water injection position P1 is performed while pushing the downstream fuel 201a and the water 202 at the second water injection position P2 to the upstream side in the flow direction.

As shown in fig. 5, at time T4 of the crank angle R4, the water 202 at the second water injection position P2 is injected by a necessary amount. On the other hand, the water 203 at the first water injection position P1 is injected over the entire width of the fuel column 201. The water 203 in this state divides the downstream side fuel 201a of the fuel column 201 into the most downstream fuel 201c located on the downstream side of the first water injection position P1 and the inter-water-injection-layer fuel 201d sandwiched between the water 202 at the second water injection position P2 and the water 203 at the first water injection position P1. Thus, the fuel amount of the inter-injection-layer fuel 201d, that is, the fuel amount between the injection layers (Qf 2) and the fuel amount of the most downstream fuel 201c are determined. The time until the water 203 at the first water injection position P1 is injected to extend over the entire width of the fuel column 201 may be the same as, or before or after the time T4 at which the water 202 at the second water injection position P2 has been injected by a necessary amount.

Thereafter, as shown in fig. 4, the control unit 92 instructs the control valve 55 of the downstream water injection system 50 to close at a time T5 when the detected crank angle value becomes the crank angle R5. Thereby, the controller 92 stops the operation of the first water injection pump 51 of the downstream side water injection system 50. According to this control, the first water injection pump 51 ends the water injection to the first water injection position P1 of the fuel circulation path. That is, the time T5 of the crank angle R5 is the water injection completion time of the downstream water injection system 50.

For example, as shown in fig. 5, the water 203 at the first water injection position P1 is further injected from a state where the water extends over the entire width of the fuel column 201 during a period from time T4 at the crank angle R4 to time T5 at the crank angle R5(> R4). On the other hand, the injection of the water 202 of the second water injection position P2 has ended at the above-described time T4. At this stage, the injection of the water 203 at the first water injection position P1 is performed in the same manner as the period from the time T3 to the time T4 described above, and the injection amount of the water 203 is continued until it becomes a necessary amount. Then, the water injection at each of the first water injection position P1 and the second water injection position P2 is finished at a time T5 of the crank angle R5. As a result, the laminar liquid 200 composed of the first fuel layer F1, the first water injection layer W1, the second fuel layer F2, the second water injection layer W2, and the third fuel layer F3 is formed in the fuel flow path.

Here, in the first embodiment, the water injection period of the upstream side water injection system 60 is a period from time T1 at a crank angle R1 to time T4 at a crank angle R4. That is, the water injection period of the upstream side water injection system 60 is an amount of time obtained by adding the standby time Δ T1, the time Δ T2, and the time Δ T3 shown in fig. 4. The water injection period is determined by the time taken to inject the necessary amount of water 202 to the second water injection position P2 shown in fig. 5. That is, the crank angle R4 corresponding to the water injection end time (time T4) of the upstream water injection system 60 is derived based on the crank angle R1 corresponding to the water injection start time and the time required for the injection of the required amount of water 202.

The water injection period of the downstream side water injection system 50 is a period from time T2 at a crank angle R2 to time T5 at a crank angle R5. The water injection period is determined by the time taken to inject the necessary amount of water 203 to the first water injection position P1 shown in fig. 5. That is, the crank angle R5 corresponding to the water injection end time (time T5) of the downstream water injection system 50 is derived based on the crank angle R2 corresponding to the water injection start time and the time required for the injection of the necessary amount of water 203.

As shown in fig. 4, in the first embodiment, the period in which the water injection period of the upstream side water injection system 60 and the water injection period of the downstream side water injection system 50 overlap corresponds to the time Δ T4 from the crank angle R2 to the crank angle R4. The time Δ T4 is a time obtained by adding the time Δ T2 in which the fuel between the water injection zones is adjusted so as to decrease (decrement adjustment) by the water injection of the downstream side water injection system 50 to the time Δ T3 from the end of the adjustment of the fuel amount between the water injection zones to the end of the water injection of the upstream side water injection system 60. The water injection start time of the downstream side water injection system 50 is controlled to be delayed by the standby time Δ T1 from the water injection start time of the upstream side water injection system 60 so that the time Δ T2 decreases with an increase in the engine load and the time Δ T2 increases with a decrease in the engine load. That is, the standby time Δ T1 increases as the engine load increases, and decreases as the engine load decreases. When the standby time Δ T1 is zero (Δ T1 is 0), the water injection start time of the downstream water injection system 50 is controlled to be the same as the water injection start time of the upstream water injection system 60.

Fig. 6 is a diagram showing an example of the injection amount of the lamellar liquid according to the engine load in the first embodiment of the present invention. The injection amount shown in fig. 6 is an injection amount per one time of the stratified charge liquid 200 (see fig. 3) injected from one fuel injection valve 30 into the combustion chamber 17 in the cylinder 12. The injection amount of the stratified liquid 200 is represented by the sum of the fuel injection amount Qfa corresponding to the engine load and the water injection amounts Qw1 and Qw2 of the first water injection layer W1 and the second water injection layer W2 (Qfa + Qw1+ Qw 2).

In the first embodiment, the ejection amount of the lamellar liquid 200 is set by controlling the start timing of each of the water injection in the downstream side water injection system 50 and the upstream side water injection system 60. For example, as shown in fig. 6, the injection amount of the lamellar liquid 200 increases with an increase in the engine load and decreases with a decrease in the engine load. In the stratified fluid 200, the amount of fuel in the second fuel layer F2 sandwiched between the first water injection layer W1 and the second water injection layer W2 (i.e., the amount of fuel between the water injection layers) is adjusted to an appropriate amount according to the engine load. Preferably, in the range of the engine load (55% or more and 100% or less in fig. 6) in which the laminar liquid 200 having the fuel layer between the water injection layers is formed in the fuel flow path, the fuel amount between the water injection layers is adjusted (optimized) so as to be in a constant proportion to the fuel injection amount Qfa that increases and decreases according to the engine load. In the lamellar liquid 200, the ratio of the water injection amount Qw1 in the first water injection layer W1 to the water injection amount Qw2 in the second water injection layer W2 is constant.

As described above, the fuel injection device 100 according to the first embodiment of the present invention includes: a fuel injection valve 30 for injecting fuel and water in layers into a combustion chamber 17 in a cylinder 12 of the marine diesel engine 10; a fuel injection pump 41 that pressure-feeds fuel to the fuel injection valve 30 through a pipe; a downstream water injection system 50 for injecting water into a first water injection position P1 on a fuel flow path from the fuel injection pump 41 to the injection port 31 of the fuel injection valve 30 by the downstream water injection system 50; and an upstream side water injection system 60 for injecting water to a second water injection position P2 on an upstream side in a fuel flow direction in the fuel flow path than the downstream side water injection system 50, wherein the water injection start timing of each of the downstream side water injection system 50 and the upstream side water injection system 60 is controlled in accordance with an engine load such that a water injection period of the downstream side water injection system 50 overlaps at least a part of a water injection period of the upstream side water injection system 60. At this time, the standby time Δ T1 of the downstream side water injection system 50 from the start of water injection by the upstream side water injection system 60 to the start of water injection by the downstream side water injection system 50 is calculated in accordance with the engine load, and the start of water injection by the downstream side water injection system 50 is delayed from the start of water injection by the calculated standby time Δ T1 of the upstream side water injection system 60.

With the above configuration, during a period in which the water injection period of the downstream side water injection system 50 overlaps the water injection period of the upstream side water injection system 60, the fuel amount between the water injection layer of the downstream side water injection system 50 and the water injection layer of the upstream side water injection system 60 (the inter-water injection layer fuel amount) can be adjusted so that the ratio of the inter-water injection layer fuel amount to the fuel injection amount Qfa according to the engine load is not excessively large or small. Therefore, when fuel and water are injected in layers from the fuel injection valve 30, the amount of fuel between the water injection layers can be appropriately adjusted according to the engine load. As a result, it is possible to suppress the occurrence of an undesirable combustion state such as poor combustion of the marine diesel engine 10 that may be caused when fuel and water are injected in layers to reduce NOx in the exhaust gas.

In the fuel injection device 100 according to the first embodiment of the present invention, the respective water injection start times of the downstream side water injection system 50 and the upstream side water injection system 60 are controlled in accordance with the engine load so that the amount of fuel between the water injection zones is in a fixed ratio to the fuel injection amount Qfa corresponding to the engine load. Therefore, when fuel and water are injected in layers from the fuel injection valve 30, the fuel between the water injection layers can be adjusted to an optimum fuel amount for each engine load. As a result, NO in the exhaust gas can be reduced most effectively _X 。

In the fuel injection device 100 according to the first embodiment of the present invention, the ratio of the water injection amount Qw1 of the downstream side water injection system 50 to the water injection amount Qw2 of the upstream side water injection system 60 is constant. Therefore, when fuel and water are injected in layers from the fuel injection valve 30, the water amount of the water injection layer to be subsequently injected into the fuel layer can be optimized for each engine load. As a result, it is possible to prevent the engine misfire (japanese language: misfire) due to the injection of water after the combustion of the fuel, ensure stable operation of the marine diesel engine 10, and most effectively reduce NO in the exhaust gas _X 。

(second embodiment)

Next, a second embodiment of the present invention will be explained. In the first embodiment described above, the respective water injection start times of the downstream side water injection system 50 and the upstream side water injection system 60 are controlled so that the water injection start time of the downstream side water injection system 50 is delayed from the water injection start time of the upstream side water injection system 60 by the standby time calculated according to the engine load, but in the present second embodiment, the respective water injection start times of the downstream side water injection system 50 and the upstream side water injection system 60 are controlled so that the water injection start time of the upstream side water injection system 60 is delayed from the water injection start time of the downstream side water injection system 50 by the standby time calculated according to the engine load.

Fig. 7 is a schematic diagram showing a configuration example of a fuel injection device according to a second embodiment of the present invention. As shown in fig. 7, the fuel injection device 110 includes a control unit 112 instead of the control unit 92 of the fuel injection device 100 according to the first embodiment. The other configurations are the same as those of the first embodiment, and the same components are denoted by the same reference numerals. Although not shown, the marine diesel engine to which the fuel injection device 110 according to the second embodiment is applied is configured in the same manner as the marine diesel engine 10 according to the first embodiment except that the control unit 112 is provided.

The control unit 112 is constituted by a CPU, a memory, a program device, and the like for executing various programs. The control unit 112 controls the water injection time of the downstream side water injection system 50 and the water injection time of the upstream side water injection system 60 in accordance with the engine load so that water is injected into each of the first water injection position P1 and the second water injection position P2 of the fuel flow path in a state where fuel is filled in the period other than the above-described stratified injection time of fuel and water. At this time, in order to overlap at least a part of the water injection period of the downstream water injection system 50 and the water injection period of the upstream water injection system 60, the control unit 112 controls the water injection start time of the first water injection pump 51 of the downstream water injection system 50 and the water injection start time of the second water injection pump 61 of the upstream water injection system 60 so that the water injection start time of the upstream water injection system 60 is delayed from the water injection start time of the downstream water injection system 50 by the standby time calculated from the engine load. Further, the control unit 112 controls the stratified charge injection time of the fuel and the water from the fuel injection valve 30 to the combustion chamber 17, similarly to the control unit 92 in the first embodiment described above.

Next, control of the water injection time for adjusting the amount of fuel between the water injection zones in the second embodiment of the present invention will be described. Fig. 8 is a diagram for explaining control of the water injection time in the second embodiment of the present invention. Fig. 9 is a diagram for explaining the adjustment of the fuel amount between the water injection zones in the second embodiment of the present invention.

In the second embodiment, the control unit 112 transmits valve control signals S1 and S2 shown in fig. 8 to the control valves 55 and 65, respectively, for example, and controls the timing of opening and closing the control valves 55 and 65. Thus, the control unit 112 controls the water injection time (first stage water injection time) of the downstream side water injection system 50 and the water injection time (second stage water injection time) of the upstream side water injection system 60 in accordance with the engine load so that the water injection period of the downstream side water injection system 50 and the water injection period of the upstream side water injection system 60 overlap each other at least partially. In this case, it is preferable that the control unit 112 controls the water injection start timing of each of the downstream side water injection system 50 and the upstream side water injection system 60 so that the amount of fuel between the layer of water injected by the downstream side water injection system 50 and the layer of water injected by the upstream side water injection system 60 is in a constant ratio to the fuel injection amount Qfa corresponding to the engine load.

Specifically, the control unit 112 has the above equation (1) set in advance, and calculates the standby time Δ T11 of the upstream side water injection system 60 as the standby time Δ T based on the equation (1), for example. The standby time Δ T11 of the upstream side water injection system 60 is the time from the start of water injection by the downstream side water injection system 50 to the start of water injection by the upstream side water injection system 60, that is, the time from the start of operation of the first water injection pump 51 to the start of operation of the second water injection pump 61. The control unit 112 delays the water injection start time of the upstream water injection system 60 from the water injection start time of the downstream water injection system 50 by the calculated standby time Δ T11.

Specifically, the control unit 112 acquires the crank angle detection value of the detection unit 91, and as shown in fig. 8, the control unit 112 instructs the control valve 55 of the downstream water injection system 50 to open and drive when the crank angle detection value reaches a time T11 of the crank angle R11. Thereby, the controller 112 starts the operation of the first water injection pump 51 of the downstream side water injection system 50. According to this control, the first water injection pump 51 starts water injection to the first water injection position P1 of the fuel circulation path. That is, time T11 of the crank angle R11 is the water injection start time of the downstream water injection system 50. As shown in fig. 9, at this time T11, the injection of water 203 into the fuel column 201 at the first water injection position P1 in the fuel flow path is started. As the water 203 starts to be injected into the first water injection position P1, the fuel between the first water injection position P1 and the second water injection position P2 starts to be pushed back toward the upstream side in the flow direction beyond the second water injection position P2. Thereby, the amount of fuel between the first water filling position P1 and the second water filling position P2 starts to be adjusted in a decreasing manner.

As shown in fig. 9, at time T0, the water injection into the fuel column 201 is not started during the period from the end of the previous fuel injection to the water injection start time (time T11). The fuel amount in the fuel column 201 at this time corresponds to the fuel injection amount Qfa described above.

Next, the control unit 112 starts the water injection of the upstream side water injection system 60 at a time delayed from the water injection start time of the downstream side water injection system 50 by the standby time Δ T11 calculated as described above. Specifically, the control unit 112 converts the standby time Δ T11 of the upstream water injection system 60 into the change amount Δ R of the crank angle based on the engine speed corresponding to the engine load and the elapsed time of the engine rotation. The controller 112 calculates the crank angle R12 by adding the obtained change amount Δ R of the crank angle to the crank angle R11 at the water injection start time (time T11) of the downstream water injection system 50. As shown in fig. 8, the control unit 112 instructs the control valve 65 of the upstream side water injection system 60 to open and drive at a time T12 when the detected crank angle value becomes the crank angle R12. Thus, the controller 112 starts the operation of the first water injection pump 61 of the upstream side water injection system 60 while continuing the operation of the first water injection pump 51 of the downstream side water injection system 50. According to this control, the second water injection pump 61 starts water injection to the second water injection position P2 of the fuel circulation path. That is, the time T12 of the crank angle R12 is the water injection start time of the upstream side water injection system 60. On the other hand, the first water injection pump 51 continues the water injection to the first water injection position P1 of the fuel circulation path. As shown in fig. 9, at this time T12, the injection of water 203 to the first water injection position P1 in the fuel column 201 within the fuel circulation path is continued, and the injection of water 202 to the second water injection position P2 is started.

Thereafter, the first water injection pump 51 continues the water injection to the first water injection position P1 of the fuel flow path until the control valve 55 is driven to close. At the same time, the second water injection pump 61 continues to inject water to the second water injection position P2 of the fuel flow path until the control valve 65 is driven to close.

For example, as shown in fig. 8 and 9, the water 203 is injected into the first water injection position P1 during a time Δ T13 from the crank angle R11 to the crank angle Ra. During this period, the water 203 is injected into the first water injection position P1 and the water 202 is injected into the second water injection position P2 during a period of time Δ Ta from the crank angle R12 to the crank angle Ra (> R12). With the injection of the water 203 at the first water injection position P1, the fuel between the first water injection position P1 and the second water injection position P2 is pushed back to the upstream side in the flow direction beyond the second water injection position P2 or the water 202. Thus, the fuel amount between the first water filling position P1 and the second water filling position P2 is adjusted in a decreasing manner during the time Δ T13.

In addition, at the time T13 of the crank angle R13 during the time Δ T13, the water 203 at the first water injection position P1 is injected to extend over the entire width of the fuel column 201. At this time, as shown in fig. 9, the water 203 of the first water injection position P1 divides the fuel column 201 into the most downstream fuel 201c located on the downstream side of the first water injection position P1 and the upstream side fuel 201e located on the upstream side of the first water injection position P1. At this stage, the amount of fuel of the most downstream fuel 201c is determined. In addition, during the period from the crank angle R13 to the crank angle R14(> R13), the water 203 at the first water injection position P1 is further injected from a state that extends over the entire width direction of the fuel column 201, and the water 202 at the second water injection position P2 continues to be injected. At this stage, the injection of the water 203 at the first water injection position P1 is performed while pushing the fuel between the first water injection position P1 and the second water injection position P2 back to the upstream side in the flow direction of the second water injection position P2.

On the other hand, at the time of the crank angle Ra, the water 202 of the second water injection position P2 is injected so as to extend over the entire width direction of the fuel column 201. At this time, the water 202 of the second water injection position P2 divides the upstream side fuel 201e in the fuel column 201 into the most upstream fuel 201b located on the upstream side of the second water injection position P2 and the inter-water-injection-layer fuel 201d sandwiched between the water 202 of the second water injection position P2 and the water 203 of the first water injection position P1. At this stage, even if the water 203 is injected at the first water injection position P1, the fuel between the first water injection position P1 and the second water injection position P2 is not pushed back to the upstream side in the flow direction beyond the water 202 at the second water injection position P2. Thus, the adjustment of the fuel amount between the first water injection position P1 and the second water injection position P2 is finished, and the fuel amount of the inter-injection-layer fuel 201d, that is, the inter-injection-layer fuel amount (Qf 2) is determined.

The time of the crank angle Ra may be the same as the time T14 of the second water filling position P2 for the necessary amount of water 202 injection, or may be before or after the time. Which of these times is to be the crank angle Ra is determined by the standby time Δ T11 corresponding to the engine load. Fig. 9 shows a case where the time of the crank angle Ra is the same as the time T14 of the crank angle R14.

As shown in fig. 8, the control unit 112 instructs the control valve 55 of the downstream water injection system 50 to close at a time T14 when the detected crank angle value becomes the crank angle R14. Thus, the controller 112 stops the operation of the first water injection pump 51 of the downstream-side water injection system 50 while continuing the operation of the second water injection pump 61 of the upstream-side water injection system 60. According to this control, the first water injection pump 51 ends the water injection to the first water injection position P1 of the fuel circulation path. That is, the time T14 of the crank angle R14 is the water injection completion time of the downstream water injection system 50. On the other hand, the second water injection pump 61 continues to inject water to the second water injection position P2 of the fuel circulation path. As shown in fig. 9, at time T14 of the crank angle R14, the water 203 at the first water injection position P1 is injected by a necessary amount.

Thereafter, as shown in fig. 8, the control unit 112 instructs the control valve 65 of the upstream side water injection system 60 to close at time T15 when the detected crank angle value becomes the crank angle R15. Thereby, the controller 112 stops the operation of the second water injection pump 61 of the upstream side water injection system 60. According to this control, the second water injection pump 61 stops water injection to the second water injection position P2 of the fuel circulation path. That is, the time T15 of the crank angle R15 is the water injection completion time of the upstream side water injection system 60.

For example, as shown in fig. 9, the water 202 at the second water injection position P2 is further injected from a state of extending over the entire width of the fuel column 201 during a period from time T14 at the crank angle R14 to time T15 at the crank angle T15(> R14). On the other hand, the injection of the water 203 at the first water injection position P1 has ended at the above-described time T14. At this stage, the injection of the water 202 at the second water injection position P2 is performed in the same manner as the period from the time T13 to the time T14, and is continued until the injection amount of the water 202 becomes the necessary amount. Then, the water injection at the second water injection position P2 and the first water injection position P1 ends at time T15 of the crank angle R15. As a result, the laminar liquid 200 composed of the first fuel layer F1, the first water injection layer W1, the second fuel layer F2, the second water injection layer W2, and the third fuel pool F3 is formed in the fuel flow path.

In the second embodiment, the water injection period of the downstream side water injection system 50 is a period from time T11 at the crank angle R11 to time T14 at the crank angle R14. That is, the water injection period of the downstream side water injection system 50 is a time period obtained by adding the standby time Δ T11 and the time Δ T12 shown in fig. 8. The water injection period is determined by the time taken to inject the necessary amount of water 203 to the first water injection position P1 shown in fig. 9. That is, the crank angle R14 corresponding to the water injection end time (time T14) of the downstream water injection system 50 is derived based on the crank angle R11 corresponding to the water injection start time and the time taken for the injection of the necessary amount of water 203.

The water injection period of the upstream water injection system 60 is a period from time T12 at the crank angle R12 to time T15 at the crank angle R15. The water injection period is determined by the time taken to inject the necessary amount of water 202 to the second water injection position P2 shown in fig. 9. That is, the crank angle R15 corresponding to the water injection end time (time T15) of the upstream side water injection system 60 is derived based on the crank angle R12 corresponding to the water injection start time and the time required for the injection of the necessary amount of water 202.

As shown in fig. 8, in the second embodiment, the period in which the water injection period of the downstream side water injection system 50 and the water injection period of the upstream side water injection system 60 overlap corresponds to the time Δ T12 from the crank angle R12 to the crank angle R14. In this period, the period of time Δ Ta from the crank angle R12 to the crank angle Ra is a part of the period in which the amount of fuel between the water injection zones is reduced and adjusted by the water injection of the downstream side water injection system 50. The period of the standby time Δ T11 from the crank angle R11 to the crank angle R12 is the remainder of the period during which the amount of fuel between the water injection layers is reduced and adjusted. That is, the period of time Δ T13 obtained by adding the standby time Δ T11 and the time Δ Ta is the entire period during which the fuel amount in the water injection layer is reduced and adjusted. The water injection start time of the upstream water injection system 60 is controlled to be delayed by the standby time Δ T11 from the water injection start time of the downstream water injection system 50 so that the time Δ T13 decreases with an increase in the engine load and the time Δ T13 increases with a decrease in the engine load. That is, the standby time Δ T11 decreases as the engine load increases, and increases as the engine load decreases. When the standby time Δ T11 is zero (Δ T11 is 0), the start time of water injection by the upstream water injection system 60 is controlled to be the same as the start time of water injection by the downstream water injection system 50.

As described above, the fuel injection device 110 according to the second embodiment of the present invention calculates the standby time Δ T11 of the upstream side watering system 60 from the start of water injection by the downstream side watering system 50 to the start of water injection by the upstream side watering system 60 based on the engine load, controls the water injection start times of the downstream side watering system 50 and the upstream side watering system 60 such that the water injection period of the downstream side watering system 50 and at least a part of the water injection period of the upstream side watering system 60 overlap each other, and delays the water injection start time of the upstream side watering system 60 from the standby time Δ T11 calculated by the downstream side watering system 50, and has the same configuration as the first embodiment. Therefore, the same operational effects as in the case of the first embodiment described above can be obtained, and the time during which the amount of fuel between the water injection zones can be reduced and adjusted by the water injection from the downstream side water injection system 50 can be adjusted to a wider range than the case in which the upstream side water injection system 60 is injected with water first, whereby the ratio of the amount of fuel between the water injection zones to the fuel injection amount corresponding to the engine load can be easily optimized.

In the first and second embodiments described above, when controlling the respective water injection start times of the downstream side water injection system 50 and the upstream side water injection system 60, the crank angle is calculated from the standby time for water injection start (for example, Δ T1 or Δ T11) calculated from the engine load, and the time when the obtained crank angle matches the detected value of the crank angle by the detection unit 91 is defined as the subsequent water injection start time of the next previous water injection start time. For example, the respective water injection start times of the downstream side water injection system 50 and the upstream side water injection system 60 may be controlled along the elapsed time (i.e., the time axis) during the engine rotation of the marine diesel engine, and the time when the elapsed time from the previous water injection start time reaches the standby time corresponding to the engine load may be set as the subsequent water injection start time.

In the first and second embodiments, the fuel injection device including three fuel injection valves 30 is exemplified, but the present invention is not limited thereto. For example, in the present invention, the number of the fuel injection valves 30 to be disposed is not limited to three, and may be one or a plurality (two or more).

The present invention is not limited to the first and second embodiments described above, and configurations in which the above-described respective components are appropriately combined are also included in the present invention. In addition, other embodiments, examples, operation techniques, and the like, which are made by those skilled in the art based on the first and second embodiments described above, are all included in the scope of the present invention.

Industrial applicability of the invention

As described above, the fuel injection device according to the present invention is suitable for injecting fuel and water into a combustion chamber in a cylinder of a marine diesel engine, and particularly suitable for a fuel injection device capable of adjusting the amount of fuel between water injection layers according to the engine load.

Description of the symbols

1 base

2 crankshaft

3 bearing

4 crank

5 framework

6 connecting rod

7 guide plate

8 crosshead

9 crosshead pin

10 diesel engine for ship

11 cylinder jacket

12 cylinder

13 cylinder liner

14 cylinder head

15 piston

16 piston rod

17 combustion chamber

18 exhaust valve

19-valve device

20 exhaust pipe

21 captive bolt

22 nut

30 fuel injection valve

31 jet nozzle

32. 33 internal flow path

34a, 34b check valve

40 fuel pressure feed system

41 fuel injection pump

42 fuel injection pipe

42a, 42b, 42c branch pipes

43 branch part

45 control valve

50 downstream side water injection system

51 first water injection pump

52 downstream side water injection pipe

52a, 52b, 52c branch pipes

53 branching part

54 check valve

55 control valve

60 upstream side water injection system

61 second water injection pump

62 upstream side water injection pipe

62a, 62b, 62c branch pipes

63 branching part

64 check valve

65 control valve

71 Water supply pump

72 Water supply pipe

72a, 72b branch pipe

73a, 73b check valve

81 pressure accumulating part

82 high pressure pump

91 detection part

92. 112 control part

100. 110 fuel injection device

200 layered liquid

201 fuel column

201a downstream side fuel

201b upstream fuel

201c most downstream fuel

201d interlayer fuel

201e upstream side fuel

202. 203 water

F1 first Fuel layer

F2 second Fuel layer

F3 third fuel layer

L1 first liquid layer

L2 second liquid layer

L3 third liquid layer

L4 fourth liquid layer

L5 fifth liquid layer

P1 first water injection position

P2 second Water injection position

S1, S2 valve control signal

W1 first water injection layer

W2 second flood layer.

Claims (7)

1. A fuel injection device is characterized by comprising:

a fuel injection valve provided in a cylinder of a marine diesel engine;

a fuel injection pump that pressure-feeds fuel to the fuel injection valve through a pipe;

a first water injection system that injects water into a predetermined position of a fuel flow path from the fuel injection pump to an injection port of the fuel injection valve;

a second water injection system that injects water to a position on an upstream side of the fuel flow direction in the fuel flow path than the first water injection system; and

a control unit that controls respective water injection start times of the first water injection system and the second water injection system so that a water injection period of the first water injection system and a water injection period of the second water injection system overlap each other at least in part according to a load of the marine diesel engine,

the control unit calculates a standby time of one water injection system of the first and second water injection systems from start of water injection by the water injection system to start of water injection by the other water injection system based on a load of the marine diesel engine, and delays the water injection start time of the other water injection system from the start of water injection by the water injection start time of the one water injection system by the calculated standby time,

the fuel injection valve injects the fuel pumped by the fuel injection pump, the water injected by the first water injection system, and the water injected by the second water injection system from the injection port to the combustion chamber in the cylinder in layers.

2. The fuel injection apparatus according to claim 1,

the control unit controls the water injection start timings of the first water injection system and the second water injection system such that the amount of fuel between the water injected from the first water injection system and the water injected from the second water injection system is proportional to the injection amount of the fuel per injection.

3. The fuel injection apparatus according to claim 1,

the control unit calculates a standby time of the first water injection system from start of water injection by the second water injection system to start of water injection by the first water injection system based on a load of the marine diesel engine, and delays a water injection start time of the first water injection system from the water injection start time of the second water injection system by the calculated standby time.

4. The fuel injection apparatus according to claim 2,

the control unit calculates a standby time of the first water injection system from the start of water injection by the second water injection system to the start of water injection by the first water injection system based on a load of the marine diesel engine, and delays the start of water injection by the first water injection system from the start of water injection by the calculated standby time.

5. The fuel injection apparatus according to claim 1,

the control unit calculates a standby time of the second water injection system from start of water injection from the first water injection system to start of water injection from the second water injection system based on a load of the marine diesel engine, and delays the water injection start time of the second water injection system from the water injection start time of the first water injection system by the calculated standby time.

6. The fuel injection apparatus according to claim 2,

the control unit calculates a standby time of the second water injection system from start of water injection from the first water injection system to start of water injection from the second water injection system based on a load of the marine diesel engine, and delays the start of water injection from the second water injection system from the start of water injection from the first water injection system by the calculated standby time.

7. The fuel injection apparatus according to any one of claims 1 to 6,

the ratio of the water injection amount of the first water injection system to the water injection amount of the second water injection system is constant.

Images