Fuel injection device

Abstract

To enable suppressing generation of deposits in a nozzle of a fuel injection valve without stopping the operation of a multiple fuel engine.SOLUTION: A fuel injection device includes: a fossil fuel injection valve which injects fossil fuel to a combustion chamber of a multiple fuel engine; an alternate fuel injection valve which injects alternate fuel to the combustion chamber; a cleaning gas infusion section which infuses cleaning gas to a non-operating valve among the fuel injection valves that is ceasing fuel injection in operation of the multiple fuel engine; a working fluid infusion section which infuses working fluid for injecting the cleaning gas to the suspended valve into the respective fuel injection valves; and a control section which controls an injection timing of the cleaning gas. The fuel injection valves each include a needle valve for opening and closing a nozzle hole of a nozzle, and an opening valve pressure adjustment section which adjusts a valve opening pressure of the needle valve by making use of the working fluid. The control section determines whether or not a cylinder inner pressure of the multiple fuel engine is less than a gas pressure of the cleaning gas, and when it is less than the gas pressure, lowers the valve opening pressure of the non-operating valve to less than the gas pressure to make the non-operating valve inject the cleaning gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fuel injection device. [Background technology]

[0002] Conventionally, internal combustion engines mounted on ships and other vessels are provided with a fuel injection valve for injecting fuel into a combustion chamber. Generally, the fuel injection valve includes a nozzle for injecting fuel pumped from a fuel pump into the combustion chamber of the internal combustion engine, a fuel passage leading to the nozzle orifice, a needle valve for opening and closing the nozzle orifice, and a valve-opening pressure adjuster for adjusting the valve-opening pressure of the needle valve. The valve-opening pressure adjuster uses spring force to pressurize the needle valve against the nozzle seat, thereby adjusting the valve-opening pressure of the needle valve to a desired fuel injection pressure (hereinafter referred to as fuel injection pressure). When the pressure of fuel in the fuel passage exceeds the needle valve opening pressure due to the pressurizing action of the fuel pump, the fuel pressure causes the needle valve to move away from the nozzle seat, opening the orifice, and fuel is injected through the orifice into the combustion chamber.

[0003] Furthermore, in the field of ships, in recent years, in order to reduce the amount of carbon dioxide emitted from internal combustion engines, so-called multi-fuel engines have been developed that can operate by burning (mixing) fossil fuels such as heavy oil, which have traditionally been used as fuel, with alternative fuels that replace the fossil fuels. The alternative fuels referred to here are fuels that emit less carbon dioxide when burned than fossil fuels, such as ammonia, methanol, or liquefied petroleum gas (LPG).

[0004] In such multi-fuel engines, multiple fuel injection valves for injecting fossil fuel and alternative fuel are provided in one cylinder. Each of these multiple fuel injection valves injects the required amount of fuel into the combustion chamber depending on the operating mode of the multi-fuel engine, such as mixed combustion of fossil fuel and alternative fuel or mono-combustion of fossil fuel. Depending on the operating mode of the multi-fuel engine, one of these multiple fuel injection valves may suspend fuel injection. For example, Patent Document 1 discloses a method and apparatus for suspending fuel injection by at least one of multiple fuel injection valves provided in one cylinder depending on the operating mode of the internal combustion engine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-190646 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, when multiple fuel injection valves are provided in one cylinder, the nozzles of these multiple fuel injection valves are exposed to a high-temperature environment caused by fuel combustion in the combustion chamber during operation of the multi-fuel engine. In particular, in a fuel injection valve that is not injecting fuel, fuel remains inside the nozzle before injection. If this remaining fuel becomes excessively hot, sludge may form at the nozzle orifice and coking may occur in the nozzle's internal passage. Such deposits, such as sludge and coking, on the nozzle can hinder proper fuel injection by the fuel injection valve. Therefore, the deposits must be removed from the nozzle. To do this, the operation of the multi-fuel engine must be stopped and the fuel injection valve must be removed from the cylinder for maintenance.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a fuel injection device that can suppress the formation of deposits on the nozzle of a fuel injection valve without stopping the operation of a multi-fuel engine. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a fuel injection device according to the present invention includes a fossil fuel injection valve that injects a fossil fuel into a combustion chamber of a multi-fuel engine that can be operated using at least one of a fossil fuel and an alternative fuel, an alternative fuel injection valve that injects the alternative fuel into the combustion chamber of the multi-fuel engine, a cleaning gas injection unit that injects cleaning gas into a nozzle of the fuel injection valve that is in a stopped state and is in a stopped state where fuel injection is stopped while the multi-fuel engine is in operation, out of the fossil fuel injection valve and the alternative fuel injection valve, and a working fluid that injects the cleaning gas from the nozzle opening of the fuel injection valve that is in a stopped state into each of the fossil fuel injection valve and the alternative fuel injection valve. and a control unit that controls the injection timing of the cleaning gas from the nozzle orifice, wherein each of the fossil fuel injection valve and the alternative fuel injection valve comprises the nozzle, a needle valve that opens and closes the nozzle orifice, and a valve opening pressure adjustment unit that adjusts the valve opening pressure of the needle valve by using the working fluid, and the control unit determines whether or not the cylinder pressure of the multi-fuel engine is less than the pressure of the cleaning gas, and operates the valve opening pressure adjustment unit so that the valve opening pressure of the fuel injection valve in a deactivated state decreases to less than the pressure of the cleaning gas when the cylinder pressure is less than the pressure of the cleaning gas, thereby causing the fuel injection valve in a deactivated state to inject the cleaning gas from the nozzle orifice.

[0009] Furthermore, in the fuel injection device according to the present invention, in the above invention, the control unit determines whether the fuel injection valve in a stopped state is the alternative fuel injection valve based on an operation mode of the multi-fuel engine, and if the alternative fuel injection valve is in a stopped state, injects the cleaning gas from the nozzle opening into the stopped alternative fuel injection valve at a timing when the in-cylinder pressure is lower than the pressure of the cleaning gas.

[0010] Furthermore, in the fuel injection device according to the present invention, in the above invention, the control unit determines whether the fuel injection valve in a stopped state is the fossil fuel injection valve based on the operating mode of the multi-fuel engine, and if the fossil fuel injection valve is in a stopped state, injects the cleaning gas from the nozzle opening into the stopped fossil fuel injection valve at a timing when the in-cylinder pressure is lower than the pressure of the cleaning gas.

[0011] Furthermore, in the fuel injection device according to the present invention, in the above invention, the control unit operates the valve opening pressure adjustment unit at a timing when the in-cylinder pressure is lower than the pressure of the cleaning gas so that the valve opening pressure of the fuel injection valve in the deactivated state becomes a pressure within a range higher than the in-cylinder pressure and lower than the pressure of the cleaning gas.

[0012] In addition, in the fuel injection device according to the present invention, the control unit determines whether or not the in-cylinder pressure is less than the pressure of the cleaning gas for each cycle period in which a piston makes one reciprocating movement within a cylinder of the multi-fuel engine.

[0013] In addition, in the fuel injection device according to the present invention, in the above invention, the valve opening pressure adjustment unit comprises a biasing spring that biases the needle valve in the direction of closing the nozzle orifice, and an action unit that uses the pressure of the working fluid to act on the biasing spring, and the valve opening pressure of the needle valve is set to a pressure greater than the pressure of the cleaning gas by the biasing force of the biasing spring, and the action unit applies a force to the biasing spring in a direction opposite to the biasing force by the pressure of the working fluid, thereby reducing the valve opening pressure of the needle valve to below the pressure of the cleaning gas.

[0014] In addition, in the fuel injection device according to the present invention, in the above invention, the valve opening pressure adjustment unit comprises a biasing spring that biases the needle valve in the direction of closing the nozzle orifice, and an action unit that uses the pressure of the working fluid to strengthen the biasing force of the biasing spring, and the valve opening pressure of the needle valve is set by the biasing force of the biasing spring strengthened by the action unit, and the action unit reduces the valve opening pressure of the needle valve to below the pressure of the cleaning gas by releasing the strengthening of the biasing force of the biasing spring.

[0015] In addition, the fuel injection device according to the present invention is characterized in that, in the above invention, it further includes a crank angle detection unit that detects a crank angle of the multi-fuel engine, and the control unit derives the in-cylinder pressure based on the detected crank angle.

[0016] In addition, the fuel injection device according to the present invention is characterized in that, in the above invention, it further includes an exhaust valve operation detection unit that detects exhaust valve operation of the multi-fuel engine, and the control unit derives the in-cylinder pressure based on the detected exhaust valve operation.

[0017] In addition, the fuel injection device according to the present invention is characterized in that, in the above invention, it further includes an in-cylinder pressure detection unit that detects the in-cylinder pressure, and the control unit determines whether the detected in-cylinder pressure is less than the pressure of the cleaning gas. [Effects of the Invention]

[0018] The present invention has an effect of providing a fuel injection device that can suppress deposition of matter on the nozzle of the fuel injection valve without stopping the operation of the multi-fuel engine. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a fuel injection device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional schematic view showing an example of the configuration of the alternative fuel injection valve according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a diagram for explaining adjustment of the valve opening pressure of the needle valve in the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining the in-cylinder pressure of a marine internal combustion engine to which the fuel injection device according to the first embodiment of the present invention is applied. [Figure 5] FIG. 5 is a diagram showing an example of an operation mode of the marine internal combustion engine according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flow chart showing an example of a method for cleaning the fuel injection valve of the fuel injection device according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a fuel injection device according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional schematic view showing an example of the configuration of an alternative fuel injection valve according to the second embodiment of the present invention. [Figure 9] FIG. 9 is a diagram illustrating adjustment of the valve opening pressure of the needle valve in the second embodiment of the present invention. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of a fuel injection device according to the third embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing an example of an operation mode of the marine internal combustion engine according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] A preferred embodiment of a fuel injection device according to the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from those in reality. The drawings may also include parts whose dimensional relationships and ratios differ from one another. In addition, the same components are designated by the same reference numerals in the various drawings.

[0021] (Embodiment 1) First, the configuration of a fuel injection device according to embodiment 1 of the present invention will be described. Fig. 1 is a block diagram showing an example of the configuration of a fuel injection device according to embodiment 1 of the present invention. Fig. 1 schematically shows a marine internal combustion engine 100 as an example of an internal combustion engine to which this fuel injection device 10 is applied.

[0022] A fuel injection device 10 according to a first embodiment of the present invention is a device that injects at least one of a fossil fuel and an alternative fuel into a combustion chamber of a marine internal combustion engine 100, and includes, for example, a fossil fuel injector 1 and an alternative fuel injector 2, as shown in Fig. 1. Also, as shown in Fig. 1, the fuel injection device 10 includes a cleansing gas injector 3 that injects a cleansing gas into each of the fossil fuel injector 1 and the alternative fuel injector 2, a working fluid injector 4 that injects a working fluid into each of the fossil fuel injector 1 and the alternative fuel injector 2, a pressure detecting unit 5 that detects the pressure of the cleansing gas, a crank angle detecting unit 6 that detects the crank angle of the marine internal combustion engine 100, and a control unit 7 that controls these components.

[0023] The fossil fuel injector 1 is a fuel injector that injects fossil fuel into a combustion chamber of a marine internal combustion engine 100, and is provided in a cylinder 101 of the marine internal combustion engine 100, as shown in Fig. 1. Also, as shown in Fig. 1, a fossil fuel pump 111 of the marine internal combustion engine 100 is connected to the fossil fuel injector 1 via a fuel pipe 113. The fossil fuel injector 1 injects fossil fuel that is pumped from the fossil fuel pump 111 via the fuel pipe 113 into the combustion chamber in the cylinder 101. Note that fossil fuel refers to general fuels that can be refined from crude oil, such as diesel fuel, distillate oil, and residual oil.

[0024] The alternative fuel injection valve 2 is a fuel injection valve that injects alternative fuel into the combustion chamber of the marine internal combustion engine 100, and, as shown in FIG. 1, is provided in the same cylinder 101 as the above-mentioned fossil fuel injection valve 1. That is, in the first embodiment, the marine internal combustion engine 100 is provided with two (two types of) fuel injection valves in one cylinder 101: the fossil fuel injection valve 1 and the alternative fuel injection valve 2. Also, as shown in FIG. 1, a pump 112 for pressurizing the alternative fuel in the marine internal combustion engine 100 is connected to the alternative fuel injection valve 2 via a fuel pipe 114. The alternative fuel injection valve 2 injects the alternative fuel, which is pressure-fed from the pump 112 via the fuel pipe 114, into the combustion chamber in the cylinder 101. Note that an alternative fuel is a fuel that replaces fossil fuel, and is a fuel that emits less carbon dioxide when burned than fossil fuels, such as liquid ammonia, methanol, liquefied petroleum gas (LPG), or liquefied natural gas (LNG).

[0025] The cleaning gas injection unit 3 injects cleaning gas for cleaning the nozzles of the fossil fuel injector 1 and the alternative fuel injector 2 into each of the fossil fuel injector 1 and the alternative fuel injector 2. In detail, as shown in FIG. 1 , the cleaning gas injection unit 3 includes a cleaning gas source 11, flow pipes 12, 13a, 13b, check valves 14a, 14b, and a first control valve 15.

[0026] The cleaning gas source 11 is a supply source of cleaning gas and is composed of, for example, a cleaning gas tank and a pump (neither of which are shown). Specific examples of the cleaning gas include compressed air and nitrogen gas. The flow pipes 12, 13a, and 13b are pipes (gas pipes) for circulating the cleaning gas delivered from the cleaning gas source 11. As shown in FIG. 1 , the flow pipe 12 is arranged to communicate between the cleaning gas source 11 and a first control valve 15. The flow pipe 13a is arranged to communicate between the first control valve 15 and the fossil fuel injector 1. The flow pipe 13b is arranged to communicate between the first control valve 15 and the alternative fuel injector 2. In other words, these two flow pipes 13a and 13b function as branch pipes branching from the flow pipe 12 via the first control valve 15.

[0027] As shown in Fig. 1, check valve 14a is provided in flow pipe 13a leading to fossil fuel injector 1. Check valve 14a allows the cleansing gas flowing through this flow pipe 13a to flow toward the fossil fuel injector 1, while preventing the cleansing gas from flowing back. As shown in Fig. 1, check valve 14b is provided in flow pipe 13b leading to alternative fuel injector 2. Check valve 14b allows the cleansing gas flowing through this flow pipe 13b to flow toward the alternative fuel injector 2, while preventing the cleansing gas from flowing back.

[0028] The first control valve 15 is configured by a branch valve or the like, and can selectively switch communication between the flow pipe 12 and the flow pipes 13a, 13b by adjusting the valve opening. For example, when injecting cleaning gas from the cleaning gas source 11 into the fossil fuel injector 1, the first control valve 15 closes the flow pipe 13b leading to the alternative fuel injector 2 and connects the flow pipe 13a leading to the fossil fuel injector 1 with the flow pipe 12 on the cleaning gas source 11 side. When injecting cleaning gas from the cleaning gas source 11 into the alternative fuel injector 2, the first control valve 15 closes the flow pipe 13a leading to the fossil fuel injector 1 and connects the flow pipe 13b leading to the alternative fuel injector 2 with the flow pipe 12 on the cleaning gas source 11 side. Furthermore, when cleaning gas is not injected into both the fossil fuel injector 1 and the alternative fuel injector 2, the first control valve 15 cuts off communication between the above-mentioned flow pipes 13a, 13b and the flow pipe 12. The valve opening of this first control valve 15 is controlled by the control unit 7, which will be described later.

[0029] The cleaning gas injection unit 3 having the above-described configuration injects cleaning gas into one of the fossil fuel injection valves 1 and the alternative fuel injection valves 2 that is in a stopped state where fuel injection is stopped during operation of the marine internal combustion engine 100 (hereinafter, sometimes abbreviated as a stopped valve). Note that "the fuel injection valve stops fuel injection" means a state where fuel is not injected during one cycle period in which the piston makes one reciprocating movement within the combustion chamber during operation of the marine internal combustion engine 100. For example, when the fossil fuel injection valve 1 is a stopped valve, the cleaning gas injection unit 3 adjusts the valve opening of the first control valve 15 to bring the flow pipe 12 and the flow pipe 13a into communication, and injects cleaning gas from the cleaning gas source 11 into the fossil fuel injection valve 1 through the flow pipes 12 and 13a. The injected cleaning gas is injected from the nozzle of the fossil fuel injection valve 1 into the combustion chamber of the marine internal combustion engine 100, thereby cleaning the nozzle orifice, etc. of the nozzle. Furthermore, when the alternative fuel injection valve 2 is a shutdown valve, the cleaning gas injection section 3 adjusts the valve opening of the first control valve 15 to bring the flow pipe 12 and the flow pipe 13b into communication, and injects cleaning gas from the cleaning gas source 11 through the flow pipes 12 and 13b into the alternative fuel injection valve 2. This injected cleaning gas is injected from the nozzle of the alternative fuel injection valve 2 into the combustion chamber of the marine internal combustion engine 100, thereby cleaning the nozzle opening and the like of the nozzle.

[0030] The working fluid injection unit 4 injects working fluid for injecting cleaning gas from the nozzle opening into the pause valve into each of the fossil fuel injection valve 1 and the alternative fuel injection valve 2. In detail, as shown in FIG. 1 , the working fluid injection unit 4 includes a working fluid source 16, flow pipes 17, 18a, 18b, and a second control valve 19.

[0031] The working fluid source 16 is a supply source of working fluid, and is configured, for example, by a working fluid tank, a pump, and the like (neither of which are shown). The working fluid is a fluid that causes the pause valve to inject cleaning gas from the nozzle outlet. The working fluid may be working oil or working gas. For example, the working oil may also be the same as the working oil that operates the exhaust valve of the marine internal combustion engine 100.

[0032] The circulation pipes 17, 18a, and 18b are pipes for circulating the working fluid delivered from the working fluid source 16. As shown in FIG. 1 , the circulation pipe 17 is arranged to communicate between the working fluid source 16 and the second control valve 19. The circulation pipe 18a is arranged to communicate between the second control valve 19 and the fossil fuel injector 1. The circulation pipe 18b is arranged to communicate between the second control valve 19 and the alternative fuel injector 2. In other words, these two circulation pipes 18a and 18b function as branch pipes that branch off from the circulation pipe 17 via the second control valve 19.

[0033] The second control valve 19 is configured by a branch valve or the like, and can selectively switch communication between the flow pipe 17 and the flow pipes 18a, 18b by adjusting the valve opening. For example, when injecting working fluid from the working fluid source 16 to the fossil fuel injector 1, the second control valve 19 closes the flow pipe 18b leading to the alternative fuel injector 2 and connects the flow pipe 18a leading to the fossil fuel injector 1 to the flow pipe 17 on the working fluid source 16 side. When injecting working fluid from the working fluid source 16 to the alternative fuel injector 2, the second control valve 19 closes the flow pipe 18a leading to the fossil fuel injector 1 and connects the flow pipe 18b leading to the alternative fuel injector 2 to the flow pipe 17 on the working fluid source 16 side. The valve opening of this second control valve 19 is controlled by the control unit 7, which will be described later.

[0034] The working fluid injection unit 4 having the above-described configuration injects working fluid into the deactivation valve of the fossil fuel injector 1 and the alternative fuel injector 2. For example, when the fossil fuel injector 1 is the deactivation valve, the working fluid injection unit 4 adjusts the valve opening of the second control valve 19 to bring the flow pipe 17 and the flow pipe 18a into communication, and injects working fluid from the working fluid source 16 into the fossil fuel injector 1 through the flow pipes 17 and 18a. The fossil fuel injector 1 uses the injected working fluid to open the nozzle orifice, enabling injection of cleansing gas from the nozzle orifice into the combustion chamber of the marine internal combustion engine 100. When the alternative fuel injector 2 is the deactivation valve, the working fluid injection unit 4 adjusts the valve opening of the second control valve 19 to bring the flow pipe 17 and the flow pipe 18b into communication, and injects working fluid from the working fluid source 16 into the alternative fuel injector 2 through the flow pipes 17 and 18b. The alternative fuel injection valve 2 uses this injected working fluid to open the nozzle opening, allowing the cleaning gas to be injected from the opening into the combustion chamber of the marine internal combustion engine 100.

[0035] The pressure detection unit 5 detects the pressure of the cleaning gas described above. More specifically, as shown in Fig. 1, the pressure detection unit 5 is provided in the flow pipe 12 that connects the cleaning gas source 11 and the first control valve 15. The pressure detection unit 5 detects the pressure of the cleaning gas flowing through the flow pipe 12, i.e., the pressure of the cleaning gas injected into the inactive valve of the fossil fuel injector 1 and the alternative fuel injector 2. The pressure detection unit 5 detects the pressure of the cleaning gas every time the cleaning gas is injected into the inactive valve, and transmits a detection signal indicating the detected pressure to the control unit 7.

[0036] The crank angle detection unit 6 detects the crank angle of the marine internal combustion engine 100. As shown in FIG. 1 , for example, the crank angle detection unit 6 is provided in the marine internal combustion engine 100, and detects the angle of a crank (not shown) of the marine internal combustion engine 100, i.e., the crank angle. The crank angle detection unit 6 detects the crank angle for each cylinder 101 of the marine internal combustion engine 100, and transmits a detection signal indicating the detected crank angle to the control unit 7.

[0037] The control unit 7 controls the injection timing of the cleaning gas from the nozzle orifice for the deactivated valve of the fossil fuel injection valve 1 and the alternative fuel injection valve 2. Specifically, the control unit 7 determines whether or not the in-cylinder pressure of the marine internal combustion engine 100 is less than the pressure of the cleaning gas. In the first embodiment, the in-cylinder pressure is the pressure inside the cylinder 101 when the marine internal combustion engine 100 is operating, and can be converted, for example, from the crank angle detected by the crank angle detection unit 6. The pressure of the cleaning gas is the pressure of the cleaning gas injected from the cleaning gas injection unit 3 into the deactivated valve, and can be detected, for example, by the pressure detection unit 5. Furthermore, from the viewpoint of improving the efficiency of cleaning the nozzle by injecting the cleaning gas, it is preferable that the control unit 7 determines whether or not the in-cylinder pressure is less than the pressure of the cleaning gas for each cycle period in which the piston makes one reciprocating movement inside the cylinder 101 of the marine internal combustion engine 100. The control unit 7 controls the valve opening degree of the first control valve 15 and the second control valve 19 at the timing when the in-cylinder pressure is lower than the pressure of the cleaning gas, thereby causing the pause valve to inject cleaning gas from the nozzle outlet.

[0038] The control unit 7 also determines the operation mode of the marine internal combustion engine 100 based on an input signal from the operation unit 120 of the marine internal combustion engine 100. Examples of operation modes of the marine internal combustion engine 100 include a multi-combustion operation mode in which the marine internal combustion engine 100 is operated by burning fossil fuel and alternative fuel (multi-combustion), and a mono-combustion operation mode in which the marine internal combustion engine 100 is operated by burning only fossil fuel or alternative fuel (mono-combustion). The control unit 7 determines whether at least the alternative fuel injection valve 2 is a deactivated valve based on the operation mode of the marine internal combustion engine 100 determined as described above. If the deactivated valve is the alternative fuel injection valve 2, the control unit 7 controls the injection timing of the cleaning gas described above for this deactivated alternative fuel injection valve 2. The control unit 7 also determines whether the deactivated valve is the fossil fuel injection valve 1 based on the operation mode. If the deactivated valve is the fossil fuel injection valve 1, the control unit 7 controls the injection timing of the cleaning gas described above for this deactivated fossil fuel injection valve 1.

[0039] The marine internal combustion engine 100 is an example of a multi-fuel engine that can operate using at least one of fossil fuel and alternative fuel, and as shown in FIG. 1 , for example, includes a cylinder 101, a propeller shaft 110, a fossil fuel pump 111, a pump 112 for pressurizing the alternative fuel, fuel pipes 113 and 114, and an operating unit 120.

[0040] The marine internal combustion engine 100 operates in response to operation of the operating unit 120 by an operator, and rotates the propulsion propeller by rotating the propeller shaft 110, thereby generating propulsion force for the marine vessel. When the marine internal combustion engine 100 is in operation, at least one of fossil fuel and alternative fuel is injected into the cylinder 101 in accordance with the operating mode instructed by the operating unit 120, and the injected fuel is burned. The fossil fuel is pressure-fed from a fossil fuel pump 111 through a fuel pipe 113 to a fossil fuel injector 1, and is injected from the fossil fuel injector 1 into the cylinder 101. The alternative fuel is pressure-fed from a pump 112, which pressurizes the alternative fuel, through a fuel pipe 114 to an alternative fuel injector 2, and is injected from the alternative fuel injector 2 into the cylinder 101. For example, a marine internal combustion engine 100 is provided with a plurality of cylinders 101, and the fuel injection device 10 according to the first embodiment is applied to the marine internal combustion engine 100 in correspondence with each of the plurality of cylinders 101.

[0041] (Configuration of fuel injection valve) Next, a description will be given of the configuration of the fuel injection valve provided in the above-mentioned fuel injection device 10. As shown in Fig. 1, the fuel injection device 10 has a fossil fuel injection valve 1 and an alternative fuel injection valve 2 as multiple fuel injection valves provided in one cylinder 101 of a marine internal combustion engine 100. Below, the configuration of each of the fossil fuel injection valve 1 and the alternative fuel injection valve 2 will be described in detail using the alternative fuel injection valve 2 as an example.

[0042] Fig. 2 is a cross-sectional schematic view showing one configuration example of the alternative fuel injection valve according to the first embodiment of the present invention. For convenience of explanation, in Fig. 2, the fuel injection side of the alternative fuel injection valve 2 is referred to as the front end side, and the side opposite to the fuel injection side is referred to as the rear end side.

[0043] As shown in Figure 2, the alternative fuel injector 2 includes a nozzle 21 having an orifice 21a at its tip, a nozzle joint 22 located at the rear end of the nozzle 21, an injector body 23 located at the rear end of the nozzle joint 22, a fastening portion 24, and a fuel receiving portion 25 located at the rear end of the injector body 23. The nozzle 21 is joined to the nozzle joint 22 by, for example, screwing its rear end into the nozzle joint 22. The nozzle joint 22 and the injector body 23 are fastened from their outer peripheries by the nut-shaped fastening portion 24, thereby connecting and fixing the rear end of the nozzle joint 22 to the tip of the injector body 23. The fuel receiving portion 25 is joined to the injector body 23 by, for example, screwing it into the rear end of the injector body 23.

[0044] 2, the alternative fuel injection valve 2 is internally provided with a fuel passage 51 through which fuel F flows and a cleansing gas passage 52 through which cleansing gas G flows. In the alternative fuel injection valve 2, the fuel F is an alternative fuel that is pressure-fed from a pump 112 (see FIG. 1). The cleansing gas G is a cleansing gas that is injected from a cleansing gas injection section 3 (see FIG. 1). Also, as shown in FIG. 2, the alternative fuel injection valve 2 is internally provided with a fuel reservoir section 21b that communicates with the nozzle hole 21a, a needle valve 26 that opens and closes the nozzle hole 21a, a push rod 27 that presses the needle valve 26 toward the nozzle hole 21a, and a valve-opening pressure adjustment section 30 that adjusts the valve-opening pressure of the needle valve 26.

[0045] The nozzle 21 constitutes the tip portion of the alternative fuel injection valve 2. As shown in FIG. 2 , the nozzle 21 has an injection port 21a, a fuel storage portion 21b, and a tip passage 21c. The injection port 21a is an opening for injecting fuel F from the alternative fuel injection valve 2, and when the alternative fuel injection valve 2 is mounted in a cylinder 101 of a marine internal combustion engine 100, the injection port 21a communicates with a combustion chamber in the cylinder 101. The fuel storage portion 21b is provided inside the nozzle 21 so as to have a hole-like shape that is longitudinal in the longitudinal direction of the needle valve 26. A tip passage 21c is provided on the tip side of the fuel storage portion 21b. The tip passage 21c is formed in a hole-like shape that is longitudinal in the longitudinal direction of the needle valve 26 and has an inner diameter that is smaller than the inner diameter of the fuel storage portion 21b. The fuel storage portion 21b communicates with the injection port 21a via the tip passage 21c. The fuel storage portion 21b stores, for example, the fuel F that has flowed in from the fuel passage 51 as fuel to be injected next time.

[0046] In addition to the fuel storage function described above, fuel reservoir 21b also functions as part of needle valve housing 41, which slidably houses needle valve 26. As shown in Fig. 2, needle valve 26 is brought into detachable contact with the inner wall (seat) of fuel reservoir 21b at the tip end thereof by the action of valve opening pressure adjuster 30. This allows needle valve 26 to open and close nozzle hole 21a, i.e., to releasably block communication between fuel reservoir 21b and nozzle hole 21a. As shown in Fig. 2, fuel reservoir 21b houses the tip end portion of needle valve 26 so that needle valve 26 can slide (reciprocate) in its longitudinal direction.

[0047] The nozzle joint 22 constitutes an intermediate portion between the nozzle 21 and the injector body 23. In detail, as shown in Fig. 2, the nozzle 21 is joined to the front end side of the nozzle joint 22, and the injector body 23 is joined to the rear end side of the nozzle joint 22. The joint between the nozzle joint 22 and the injector body 23 is fixed by a fastening portion 24, whereby the nozzle 21 and the injector body 23 are fixed together via the nozzle joint 22.

[0048] 2, the nozzle joint 22 has an insertion hole 22a, a fuel passage 22b, and a cleaning gas passage 22c. The insertion hole 22a constitutes part of a needle valve housing 41 that slidably houses the needle valve 26 and is provided inside the nozzle joint 22 so as to form a hole extending in the longitudinal direction of the needle valve 26. For example, as shown in FIG. 2, the insertion hole 22a communicates with a fuel reservoir 21b in the nozzle 21 and slidably houses the rear end portion of the needle valve 26. That is, the needle valve housing 41 is composed of the fuel reservoir 21b and the insertion hole 22a. The needle valve 26 is housed inside the needle valve housing 41 so as to be able to slide (reciprocate) in its longitudinal direction.

[0049] The fuel passage 22b is a passage that constitutes a part of the fuel passage 51 through which the fuel F flows. As shown in FIG. 2, the fuel passage 22b is provided inside the nozzle joint 22 so as to communicate between the fuel passage 23a of the injection valve body 23 and the fuel storage section 21b of the nozzle 21. The cleansing gas passage 22c is a passage that constitutes a part of the cleansing gas passage 52 through which the cleansing gas G flows. As shown in FIG. 2, the cleansing gas passage 22c is provided inside the nozzle joint 22 so as to communicate between the cleansing gas passage 23b of the injection valve body 23 and the fuel storage section 21b of the nozzle 21.

[0050] The injector body 23 forms a housing including the rear end portion of the alternative fuel injector 2. As shown in FIG. 2, the injector body 23 has a fuel passage 23a and a cleansing gas passage 23b. The fuel passage 23a is a passage that constitutes a part of the fuel passage 51 through which the fuel F flows. As shown in FIG. 2, the fuel passage 23a is provided inside the injector body 23 so as to communicate between an internal passage (not shown) of the fuel receiving portion 25 and the fuel passage 22b of the nozzle joint 22. The cleansing gas passage 23b is a passage that constitutes a part of the cleansing gas passage 52 through which the cleansing gas G flows. As shown in FIG. 2, the cleansing gas passage 23b is provided inside the injector body 23 so as to communicate between the flow pipe 13b of the cleansing gas injection portion 3 and the cleansing gas passage 22c of the nozzle joint 22.

[0051] 2, the injection valve body 23 has a push rod 27 for operating the needle valve 26, an insertion hole 23d through which the push rod 27 passes, a fluid passage 23c through which the working fluid E flows, and a valve-opening pressure adjustment unit 30 that adjusts the valve-opening pressure of the needle valve 26 using the working fluid E. The working fluid E is injected from the working fluid injection unit 4 (see FIG. 1). As shown in FIG. 2, the valve-opening pressure adjustment unit 30 has a biasing spring 31 that applies a biasing force to the needle valve 26, an adjustment screw 32 that adjusts the biasing force of the biasing spring 31, a piston 33 that uses the pressure of the working fluid E to weaken the biasing force from the biasing spring 31 to the needle valve 26, and an accommodation unit 35 that accommodates the biasing spring 31, the adjustment screw 32, and the piston 33.

[0052] As shown in Fig. 2, the insertion hole 23d is provided inside the injection valve body 23 so as to have a hole-like shape that is longitudinal in the longitudinal direction of the needle valve 26. As shown in Fig. 2, the push rod 27 is inserted into the insertion hole 23d and housed inside the insertion hole 23d so as to be able to reciprocate in the longitudinal direction of the needle valve 26. One end (tip end) of the push rod 27 is joined to the rear end of the needle valve 26, and the other end (rear end) of the push rod 27 is joined to the piston 33. The push rod 27 slides together with the needle valve 26 while transmitting the biasing force of the biasing spring 31 to the needle valve 26 via the piston 33.

[0053] As shown in FIG. 2 , the biasing spring 31 is a coil spring attached to a rod-shaped portion 34 extending from the piston portion 33 and housed inside the housing portion 35. The biasing spring 31 is constantly compressed from its natural length, thereby generating a biasing force. This biasing force urges the needle valve 26 in a direction to close the nozzle orifice 21 a of the nozzle 21. The biasing spring 31 applies this biasing force to the piston portion 33, thereby urging the needle valve 26 together with the piston portion 33 and the push rod 27 toward the nozzle orifice 21 a of the nozzle 21 (in the direction to close the nozzle orifice 21 a of the nozzle 21). The biasing force of the biasing spring 31 presses the needle valve 26 against the seat portion of the fuel storage portion 21 b, closing the nozzle orifice 21 a. In other words, the valve-opening pressure of the needle valve 26 is set by the biasing force of the biasing spring 31.

[0054] The adjusting screw 32 is housed inside the housing 35 while receiving the rear end of the biasing spring 31. The adjusting screw 32 changes the compression amount of the biasing spring 31 while threadedly engaging with the housing 35, thereby adjusting the biasing force due to the compression of the biasing spring 31. The valve-opening pressure adjusting unit 30 adjusts the valve-opening pressure of the needle valve 26 to the target fuel injection pressure by adjusting the biasing force of the biasing spring 31 with the adjusting screw 32.

[0055] The piston portion 33 is an example of an acting portion that uses the pressure of the working fluid E to act on the biasing spring 31. Specifically, as shown in FIG. 2 , the piston portion 33 is slidably housed within the housing portion 35 while receiving the tip end of the biasing spring 31. An actuation chamber 36, which is a space surrounded by the outer wall surface of the piston portion 33 and the inner wall surface of the housing portion 35, is formed on the tip side of the housing portion 35. Also, as shown in FIG. 2 , a push rod 27 joined to the needle valve 26 is fixed to the tip end of the piston portion 33. The piston portion 33 uses the pressure of the working fluid E injected into the actuation chamber 36 from the flow pipe 18 b of the working fluid injection portion 4 through the fluid passage 23 c to apply a force (hereinafter referred to as a resistance force) to the biasing spring 31 in a direction that resists the biasing force of the biasing spring 31. This direction is toward the rear end of the alternative fuel injection valve 2, i.e., a direction away from the injection port 21 a of the nozzle 21. The valve opening pressure adjusting unit 30 reduces the valve opening pressure of the needle valve 26 to a pressure lower than the pressure of the cleaning gas by the action of the piston unit 33.

[0056] 2, a fuel receiving portion 25 is attached to the rear end of the injection valve body 23 by a method such as screwing. The fuel receiving portion 25 constitutes a part of a fuel passage 51 through which the fuel F flows. For example, the fuel receiving portion 25 has an internal passage (not shown) that connects the fuel pipe 114 with the fuel passage 23a of the injection valve body 23, and receives the fuel F (alternative fuel in the alternative fuel injection valve 2) from the fuel pipe 114. The fuel receiving portion 25 distributes the received fuel F toward the fuel passage 23a. The fuel receiving portion 25, the fuel passage 23a of the injection valve body 23 described above, and the fuel passage 22b of the nozzle joint portion 22 constitute the fuel passage 51 through which the fuel F flows toward the nozzle orifice 21a of the nozzle 21.

[0057] Although not specifically shown, the configuration of the fossil fuel injector 1 is the same as the configuration of the alternative fuel injector 2 shown in FIG. 2, except that the target of injection is a fossil fuel.

[0058] (Adjustment of valve opening pressure) Next, the adjustment of the valve opening pressure of the needle valve 26 in each of the above-mentioned fossil fuel injector 1 and alternative fuel injector 2 will be described in detail. FIG. 3 is a diagram for explaining the adjustment of the valve opening pressure of the needle valve in embodiment 1 of the present invention. FIG. 3 schematically shows an enlarged cross-sectional view of the alternative fuel injector 2. The adjustment of the valve opening pressure of the needle valve 26 will be described below using the alternative fuel injector 2 as an example, but this adjustment of the valve opening pressure is similar to the adjustment of the valve opening pressure of the needle valve 26 in the fossil fuel injector 1.

[0059] In the first embodiment, the valve opening pressure of the needle valve 26 (see FIG. 2) (hereinafter referred to as the valve opening pressure P V The valve-opening pressure P 1 of the needle valve 26 is adjusted by the valve-opening pressure adjusting unit 30. More specifically, as shown in FIG. 3, the valve-opening pressure adjusting unit 30 generates a biasing force in a direction to close the nozzle orifice 21a of the nozzle 21 (the direction of arrow Y1 in FIG. 3) by adjusting the compression amount of the biasing spring 31 with an adjustment screw 32. The biasing force of the biasing spring 31 presses the needle valve 26 together with the piston portion 33 and the push rod 27 against the seat portion of the fuel storage portion 21b shown in FIG. 2. As a result, the needle valve 26 closes the nozzle orifice 21a, and the valve-opening pressure P 1 of the needle valve 26 is V is set to a target fuel injection pressure. This fuel injection pressure is, for example, higher than the pressure of the alternative fuel remaining unpressurized inside the fuel passage 51, and lower than the pressure of the alternative fuel pressurized by the pump 112. Also, this fuel injection pressure is extremely higher than the pressure of the cleaning gas. That is, the valve opening pressure P V is the pressure of the cleaning gas G injected (pressurized) from the cleaning gas injection part 3 by the biasing force of the biasing spring 31 (hereinafter referred to as gas pressure P G The pressure is set to be higher than the pressure at the

[0060] The valve opening pressure P VThe piston 33 acts on the biasing spring 31 using the pressure of the working fluid E, and the gas pressure P G 3, the working fluid E is injected (pressurized) into the working chamber 36 from the flow pipe 18b through the fluid passage 23c. The piston 33 slides in a direction (the direction of the arrow Y2 in FIG. 3) against the biasing force of the biasing spring 31 due to the pressure of the injected working fluid E, generating a resistance force in that direction. The piston 33 applies this generated resistance force to the biasing spring 31, thereby weakening the biasing force transmitted from the biasing spring 31 to the needle valve 26. As a result, the piston 33 reduces the valve-opening pressure P V The gas pressure P G From the viewpoint of preventing the backflow of gas from the combustion chamber of the marine internal combustion engine 100 into the nozzle 21, the valve opening pressure P V is higher than the cylinder pressure of the marine internal combustion engine 100, and the gas pressure P G It is preferable that the pressure be adjusted to a value lower than the pressure at which the pressure is increased.

[0061] On the other hand, when the injection of the working fluid E into the working chamber 36 is stopped, the pressure of the working fluid E inside the working chamber 36 drops, and the resistance force exerted by the piston portion 33 on the biasing spring 31 weakens. In this case, the biasing spring 31 pushes back the piston portion 33 in the direction to close the nozzle hole 21a, and applies the biasing force to the needle valve 26 that was there before the resistance force acted. As a result, the valve opening pressure P V The pressure of the working fluid E returns to the original fuel injection pressure. As the piston portion 33 is pushed back by the biasing spring 31, the working fluid E may be returned from the working chamber 36 to the working fluid injector 4 via the fluid passage 23c, or may be discharged to the outside of the alternative fuel injection valve 2 via a drain path (not shown) formed in the alternative fuel injection valve 2.

[0062] (Cylinder pressure of marine internal combustion engines) Next, the in-cylinder pressure of a marine internal combustion engine 100 to which the fuel injection device 10 according to the first embodiment of the present invention is applied will be described. Fig. 4 is a schematic diagram for explaining the in-cylinder pressure of a marine internal combustion engine to which the fuel injection device according to the first embodiment of the present invention is applied. As shown in Fig. 4, the marine internal combustion engine 100 includes a piston 102 that is reciprocally disposed inside a cylinder 101, an exhaust valve 104 for discharging exhaust gas after fuel combustion from a combustion chamber 103, and a crank 105 that converts the reciprocating motion of the piston 102 into the rotational motion of a crankshaft 106. The piston 102 has an upper end (piston crown) facing the combustion chamber 103 in the cylinder 101, and the pressure of the combustion chamber 103, i.e., the in-cylinder pressure P S At the top dead center A in the cylinder 101 T and bottom dead center A B The exhaust valve 104 moves back and forth between the bottom dead center A and the bottom dead center B while the piston 102 moves back and forth within the cylinder 101. B From top dead center A T While the piston 102 is moving upward (while the piston 102 is moving upward), the crank 105 is driven to open and close to discharge exhaust gas from the combustion chamber 103. The crank 105 rotates around the axis of the crankshaft 106 in accordance with the reciprocating motion of the piston 102. The crankshaft 106 rotates together with the crank 105 to rotate the propeller shaft 110 (see FIG. 1) of the marine internal combustion engine 100.

[0063] In the marine internal combustion engine 100 as described above, the in-cylinder pressure P S is the piston 102 at the top dead center A in the cylinder 101. T and bottom dead center A B For example, when the piston 102 moves back and forth between the top dead center A and the bottom dead center B due to the combustion energy of the fuel injected into the combustion chamber 103, T Bottom dead center A from the side B As the cylinder slides (downward), the cylinder pressure P S decreases from its maximum pressure. B Top dead center A from the side T As the cylinder slides upward (upward), the cylinder pressure P S increases from the minimum pressure. Therefore, the cylinder pressure PS A predetermined correlation is established between the increase and decrease of the pressure. Hereinafter, unless otherwise specified, one cycle period refers to the period during which the piston 102 makes one reciprocating movement within the cylinder 101.

[0064] In addition, the cylinder pressure P S The correlation between the increase and decrease of the torque and the rotational movement of the crank 105, which rotates once with one reciprocating movement of the piston 102, is the same. For example, when the piston 102 reaches the top dead center A T When the angle [deg] of the crank 105 when the crank is positioned at the reference angle (0 deg), the change in the angle of the crank 105 (hereinafter referred to as the crank angle θ) during one cycle (0≦θ≦360) and the in-cylinder pressure P S There is a predetermined correlation between the increase and decrease of the in-cylinder pressure P S can be derived based on the above correlation with the crank angle θ in one cycle period.

[0065] In detail, as shown in FIG. 4, when the crank angle θ is equal to or larger than the first angle α and equal to or smaller than the second angle β (α≦θ≦β), the in-cylinder pressure P S is equal to or less than a predetermined pressure. When the crank angle θ is equal to or greater than 0 degrees and less than the first angle α (0≦θ<α) or is greater than the second angle β and less than 360 degrees (β≦θ≦360), the in-cylinder pressure P S is a pressure that exceeds the predetermined pressure. For example, when the crank angle θ is equal to or greater than 50 degrees and equal to or less than 330 degrees (α=50 degrees, β=330 degrees), the in-cylinder pressure P S is 5 MPa or less based on the above correlation. In addition, when the crank angle θ is 65 degrees or more and 320 degrees or less (α=65 degrees, β=320 degrees), the in-cylinder pressure P S In the first embodiment, the in-cylinder pressure P S is the pressure of the cleaning gas G (gas pressure P G ) and the cylinder pressure P S and gas pressure P G The magnitude relationship between these two is determined.

[0066] (Operating modes of marine internal combustion engines) Next, the operation modes of the marine internal combustion engine 100 in the first embodiment of the present invention will be described. The marine internal combustion engine 100 is a multi-fuel engine that operates by combusting at least one of a fossil fuel injected from a fossil fuel injection valve 1 and an alternative fuel injected from an alternative fuel injection valve 2. Such a marine internal combustion engine 100 has a plurality of operation modes depending on the type of fuel to be combusted.

[0067] Fig. 5 is a diagram showing an example of operation modes of the marine internal combustion engine in embodiment 1 of the present invention. As shown in Fig. 5, the operation modes of the marine internal combustion engine 100 include, for example, a dual-fuel operation mode, a first mono-fuel operation mode, and a second mono-fuel operation mode.

[0068] The multi-fuel operation mode is an operation mode in which the marine internal combustion engine 100 operates by burning a mixture of fossil fuel and alternative fuel. In the multi-fuel operation mode, fossil fuel is injected into the combustion chamber 103 as pilot fuel from the fossil fuel injector 1 for each cycle period, and alternative fuel is injected into the combustion chamber 103 from the alternative fuel injector 2 following the pilot fuel. The pilot fuel is injected and ignites before the alternative fuel, which is the main fuel, thereby facilitating the ignition and combustion of the alternative fuel. The marine internal combustion engine 100 operates by burning (mixing) the pilot fuel and alternative fuel. In this multi-fuel operation mode, as shown in FIG. 5 , the fossil fuel injector 1 injects pilot fuel and the alternative fuel injector 2 injects alternative fuel for each cycle period, and therefore, there are no halted valves among the fossil fuel injector 1 and the alternative fuel injector 2 that halt fuel injection during one cycle period.

[0069] The first dedicated combustion operation mode is an operation mode in which the marine internal combustion engine 100 operates by burning only fossil fuel. In the first dedicated combustion operation mode, fossil fuel is injected from the fossil fuel injection valve 1 into the combustion chamber 103 for each cycle period. The marine internal combustion engine 100 operates by burning only the fossil fuel injected from the fossil fuel injection valve 1 (dedicated combustion). In this first dedicated combustion operation mode, as shown in FIG. 5 , the fossil fuel injection valve 1 injects fossil fuel for each cycle period, and the alternative fuel injection valve 2 pauses injection of the alternative fuel, so that of the fossil fuel injection valve 1 and the alternative fuel injection valve 2, the alternative fuel injection valve 2 is a paused valve.

[0070] The second exclusive combustion operation mode is an operation mode in which the marine internal combustion engine 100 operates by burning only the alternative fuel. In the second exclusive combustion operation mode, the alternative fuel is injected from the alternative fuel injection valve 2 into the combustion chamber 103 for each cycle period. The marine internal combustion engine 100 operates by burning only the alternative fuel injected from the alternative fuel injection valve 2 (exclusive combustion). In this second exclusive combustion operation mode, as shown in FIG. 5 , the alternative fuel injection valve 2 injects the alternative fuel for each cycle period, and the fossil fuel injection valve 1 pauses injection of the fossil fuel, so that of the fossil fuel injection valve 1 and the alternative fuel injection valve 2, the fossil fuel injection valve 1 is a paused valve.

[0071] (How to clean a fuel injection valve) Next, a method for cleaning a fuel injection valve by the fuel injection device 10 according to the first embodiment of the present invention will be described. Fig. 6 is a flow chart showing an example of a method for cleaning a fuel injection valve by the fuel injection device according to the first embodiment of the present invention. The fuel injection device 10 cleans the nozzles of the inactive valves of the fossil fuel injection valve 1 and the alternative fuel injection valve 2 with cleaning gas G by sequentially performing the processes of steps S101 to S105 shown in Fig. 6.

[0072] 6, the fuel injection device 10 determines whether or not a deactivation valve is present for the fossil fuel injector 1 and the alternative fuel injector 2 provided in the cylinder 101 of the marine internal combustion engine 100 (step S101). In step S101, the control unit 7 acquires an operation mode signal indicating the operation mode of the marine internal combustion engine 100 from the operation unit 120, and recognizes the current operation mode of the marine internal combustion engine 100 based on the acquired operation mode signal. Based on the recognized operation mode, the control unit 7 determines whether or not a deactivation valve is present among the fossil fuel injector 1 and the alternative fuel injector 2, and if a deactivation valve is present, which of the fossil fuel injector 1 and the alternative fuel injector 2 is the deactivation valve.

[0073] For example, as shown in Fig. 5, the operating modes of the marine internal combustion engine 100 include a multi-fuel operating mode, a first mono-fuel operating mode, and a second mono-fuel operating mode. The control unit 7 determines whether the operating mode of the marine internal combustion engine 100 is the multi-fuel operating mode, the first mono-fuel operating mode, or the second mono-fuel operating mode based on the above-mentioned operating mode signal. When the operating mode of the marine internal combustion engine 100 is the multi-fuel operating mode, the control unit 7 determines that there is no deactivation valve among the fossil fuel injector 1 and the alternative fuel injection valve 2. When the operating mode of the marine internal combustion engine 100 is the first mono-fuel operating mode, the control unit 7 determines that there is a deactivation valve among the fossil fuel injector 1 and the alternative fuel injection valve 2, and that this deactivation valve is the alternative fuel injection valve 2. When the operating mode of the marine internal combustion engine 100 is the first mono-fuel operating mode, the control unit 7 determines that there is a deactivation valve among the fossil fuel injector 1 and the alternative fuel injection valve 2, and that this deactivation valve is the fossil fuel injection valve 1.

[0074] In step S101, if either the fossil fuel injection valve 1 or the alternative fuel injection valve 2 is a stop valve (step S101, Yes), the fuel injection device 10 determines whether the in-cylinder pressure P S The pressure of the cleaning gas G of the stop valve (gas pressure P G ) (Step S102). The cleaning gas G is a gas that is injected (pressurized) from the cleaning gas injection unit 3 into the inactive valve in order to clean the nozzle 21 of the inactive valve.

[0075] In step S102, the pressure detection unit 5 detects the pressure of the cleaning gas G pressure-fed from the cleaning gas source 11 to the flow pipe 12 as a gas pressure P G The detected gas pressure P G Based on the detection signal from the pressure detection unit 5, the control unit 7 detects the gas pressure P G The crank angle detection unit 6 also detects the crank angle θ (see FIG. 4) in one cycle period of the marine internal combustion engine 100 in time series, and transmits a detection signal indicating the detected crank angle θ to the control unit 7 each time. The control unit 7 sequentially acquires the crank angle θ based on the detection signal from the crank angle detection unit 6. The control unit 7 calculates the in-cylinder pressure P of the marine internal combustion engine 100 based on the acquired crank angle θ. S The control unit 7 derives the in-cylinder pressure P S and gas pressure P G Compared with the cylinder pressure P S is the gas pressure P G It is determined whether it is less than or equal to the predetermined value.

[0076] For example, if the cleaning gas G has a pressure of more than 5 MPa (gas pressure P G >5MPa), the cylinder pressure P S When the crank angle θ is between 50° and 330°, the gas pressure P G In addition, the cleaning gas G is a gas with a pressure of more than 3 MPa (gas pressure P G >3MPa), the cylinder pressure P S When the crank angle θ is between 65° and 320°, the gas pressure P G It will be less than.

[0077] In step S102, the in-cylinder pressure P S is the gas pressure P G If it is equal to or greater than this (No in step S102), the fuel injection device 10 repeats the process of step S102. S is the gas pressure P GIf the pressure is less than the predetermined pressure (Yes in step S102), the fuel injection device 10 adjusts the valve opening pressure P V In step S103, the control unit 7 controls the working fluid injecting unit 4 to inject the working fluid E into the stop valve, and the valve opening pressure P V is the gas pressure P G The valve opening pressure adjusting section 30 of the corresponding stop valve is operated by the pressure of the working fluid E so that the pressure of the working fluid E drops to less than the predetermined value.

[0078] For example, when the fossil fuel injector 1 is a shutdown valve, the control unit 7 controls the valve opening degree of the second control valve 19 to open the flow pipe 18a leading to the fossil fuel injector 1 and close the flow pipe 18b leading to the alternative fuel injector 2. As a result, the second control valve 19 brings only one of these flow pipes 18a, 18b, into a state in which the flow pipe 17 is in communication with the flow pipe 18a. The working fluid source 16 injects the working fluid E into the working chamber 36 of the fossil fuel injector 1 through the flow pipes 17, 18a, etc. in a communicated state. In the valve-opening pressure adjusting unit 30 of this fossil fuel injector 1, the piston 33 uses the pressure of the working fluid E injected into the working chamber 36 to generate a resistance force that resists the biasing force of the biasing spring 31, and causes this resistance force to act on the biasing spring 31. As a result, the piston 33 controls the valve-opening pressure P of the needle valve 26 caused by the biasing force of the biasing spring 31. V The gas pressure P of the cleaning gas G injected into the fossil fuel injector 1 G The valve opening pressure P V is larger than the pressure of the fossil fuel remaining without being pressurized in the fuel passage 51 of the fossil fuel injector 1. The remaining fossil fuel may be removed from the fossil fuel injector 1 in advance before the injection of the cleaning gas G.

[0079] Furthermore, when the alternative fuel injection valve 2 is a shutdown valve, the control unit 7 controls the valve opening degree of the second control valve 19 so as to open the flow pipe 18b leading to the alternative fuel injection valve 2 and close the flow pipe 18a leading to the fossil fuel injection valve 1. As a result, the second control valve 19 brings only one of these flow pipes 18a, 18b, 18b into a state in which the flow pipe 17 is in communication with the flow pipe 18b. The working fluid source 16 injects the working fluid E into the working chamber 36 of the alternative fuel injection valve 2 through the flow pipes 17, 18b, etc. in a communicated state. Note that the operation of the valve opening pressure adjusting unit 30 in this alternative fuel injection valve 2 (the operation of the piston unit 33 using the pressure of the working fluid E) is the same as in the case of the fossil fuel injection valve 1 described above. As a result, the valve opening pressure P V is the gas pressure P of the cleaning gas G injected into the alternative fuel injection valve 2. G The valve opening pressure P V is larger than the pressure of the alternative fuel that is not pressurized and remains in the fuel passage 51 of the alternative fuel injection valve 2. The remaining alternative fuel may be removed from the alternative fuel injection valve 2 in advance before the injection of the cleaning gas G.

[0080] Regardless of whether the fossil fuel injection valve 1 or the alternative fuel injection valve 2 is a deactivation valve, the control unit 7 controls the in-cylinder pressure P S is the gas pressure P G At the timing above, the opening pressure P V is the cylinder pressure P S The pressure of the cleaning gas G (gas pressure P G It is preferable to operate the valve opening pressure adjusting unit 30 of the corresponding stop valve so that the pressure is within a range of less than 1 / 2.

[0081] After performing the above-mentioned step S103, the fuel injection device 10 injects the cleaning gas G from the pause valve (step S104). In step S104, the control unit 7 controls the cleaning gas injector 3 to inject the cleaning gas G into the pause valve, and injects the injected cleaning gas G from the nozzle 21 a of the nozzle 21 of the pause valve into the combustion chamber 103 of the marine internal combustion engine 100.

[0082] For example, when the fossil fuel injector 1 is a shutdown valve, the control unit 7 controls the valve opening of the first control valve 15 so as to open the flow pipe 13a leading to the fossil fuel injector 1 and close the flow pipe 13b leading to the alternative fuel injector 2. As a result, the first control valve 15 brings only one of these flow pipes 13a, 13b, 13a into a state of communication with the flow pipe 12. The cleaning gas source 11 injects cleaning gas G into the cleaning gas passage 52 of the fossil fuel injector 1 through the flow pipes 12, 13a, etc. that are in a communicated state. The cleaning gas G in this cleaning gas passage 52 is pressurized from the cleaning gas source 11 through the flow pipes 12, 13a, etc. The gas pressure P of such cleaning gas G G is the valve opening pressure P V Therefore, the cleaning gas G pushes open the needle valve 26, flows through the cleaning gas passage 52, and then flows through the nozzle 21, and is injected from the nozzle hole 21a of the nozzle 21 into the combustion chamber 103 of the marine internal combustion engine 100. In this way, the control unit 7 controls the cylinder pressure P S is the gas pressure P G At a timing less than 100°C, the fossil fuel injector 1 in a stopped state is made to inject cleaning gas G from the nozzle 21a of the nozzle 21 into the combustion chamber 103. By injecting this cleaning gas G, the inside of the nozzle 21 of the fossil fuel injector 1 (the nozzle 21a, the tip passage 21c, etc.) can be cleaned.

[0083] Furthermore, when the alternative fuel injection valve 2 is a shutdown valve, the control unit 7 controls the valve opening of the first control valve 15 so as to open the flow pipe 13b leading to the alternative fuel injection valve 2 and close the flow pipe 13a leading to the fossil fuel injection valve 1. As a result, the first control valve 15 brings only one of these flow pipes 13a, 13b, 13b into a state in which the flow pipe 12 is in communication with the flow pipe 13b. The cleaning gas source 11 injects cleaning gas G into the cleaning gas passage 52 of the alternative fuel injection valve 2 through the flow pipes 12, 13b, etc. in a communicated state. Note that the cleaning gas G injected into the cleaning gas passage 52 pushes open the needle valve 26 and is injected from the nozzle hole 21a of the nozzle 21 into the combustion chamber 103, just as in the case of the fossil fuel injection valve 1 described above. In this way, the control unit 7 controls the in-cylinder pressure P S is the gas pressure P GAt a timing less than 100°C, the alternative fuel injection valve 2 in a stopped state is made to inject cleaning gas G from the nozzle 21a of the nozzle 21 into the combustion chamber 103. By injecting this cleaning gas G, the inside of the nozzle 21 of the alternative fuel injection valve 2 (the nozzle 21a, the tip passage 21c, etc.) can be cleaned.

[0084] In step S104, the injection of the cleaning gas G is performed when the in-cylinder pressure P S is the gas pressure P G The control unit 7 may perform the control at all times for a predetermined period of time that is less than 100 msec, or may perform the control at a part of the predetermined period of time. S is the gas pressure P G By the time the above timing is reached, the cleaning gas injection unit 3 is controlled to stop the injection of the cleaning gas G. At this time, the control unit 7 controls the valve opening of the first control valve 15 to close both of the flow pipes 13a and 13b. This stops the injection of the cleaning gas G into the pause valve.

[0085] After executing step S104, the fuel injection device 10 returns to step S101 and sequentially executes the processes from step S101 onwards. On the other hand, if neither the fossil fuel injection valve 1 nor the alternative fuel injection valve 2 is a deactivated valve in step S101 (step S101, No), the fuel injection device 10 determines the valve opening pressure P V is set as the fuel injection pressure (step S105).

[0086] In step S105, the control unit 7 controls the working fluid injector 4 to stop the injection of the working fluid E into the fuel injector (the fossil fuel injector 1 or the alternative fuel injector 2 in the first embodiment) that is to resume the suspended fuel injection, thereby reducing the valve opening pressure P VThe control unit 7 resets or maintains the working fluid E at the fuel injection pressure. At this time, the control unit 7 controls the working fluid source 16 to recover the working fluid E that was injected into the working chamber 36 of the deactivation valve. As a result, the piston unit 33 stops generating resistance against the biasing force of the biasing spring 31. Thereafter, the control unit 7 controls the valve opening degree of the second control valve 19 to close each of the flow pipes 18a, 18b. As a result, the second control valve 19 blocks communication between the flow pipe 17 and the flow pipes 18a, 18b, and stops the flow of the working fluid E through these flow pipes 17 and 18a, 18b. Furthermore, in each of the fossil fuel injector 1 and the alternative fuel injector 2, the biasing spring 31 applies the biasing force, which was applied before receiving the resistance force from the piston unit 33, to the needle valve 26 via the piston unit 33, etc. As a result, the valve opening pressure P of the needle valve 26 V In step S105, the working fluid E may be removed from the drain paths of the fossil fuel injector 1 and the alternative fuel injector 2.

[0087] After executing step S105 described above, the fuel injection device 10 returns to step S101 described above and sequentially executes the processes from step S101 onwards. Note that, from the viewpoint of improving the efficiency of cleaning the nozzle by injecting the cleaning gas, the fuel injection device 10 preferably executes each of the processes from step S102 to S104 described above for each cycle period.

[0088] As described above, the fuel injection device 10 according to the first embodiment of the present invention includes the fossil fuel injection valve 1 that injects fossil fuel into the combustion chamber 103 of the marine internal combustion engine 100, the alternative fuel injection valve 2 that injects alternative fuel into the combustion chamber 103, the cleaning gas injection unit 3 that injects cleaning gas G into the deactivated valves of the fossil fuel injection valve 1 and the alternative fuel injection valve 2, the working fluid injection unit 4 that injects working fluid E into each of the fossil fuel injection valve 1 and the alternative fuel injection valve 2, and the control unit 7 that controls the injection timing of the cleaning gas G from the nozzle 21 a of the nozzle 21 of the deactivated valve. Each of the fossil fuel injection valve 1 and the alternative fuel injection valve 2 also includes a needle valve 26 that opens and closes the nozzle 21 a of the nozzle 21, and a valve opening pressure P of the needle valve 26 using the working fluid E. VIn the fuel injection device 10, the control unit 7 adjusts the in-cylinder pressure P S is the pressure of the cleaning gas G (gas pressure P G ) and determine whether the cylinder pressure P S is the gas pressure P G At the timing when the valve opening pressure P V is the gas pressure P G The valve opening pressure adjusting unit 30 is operated so that the pressure drops to less than 1000 kJ / s, and cleaning gas G is sprayed from the nozzle 21a of the nozzle 21 to the stop valve.

[0089] With the above configuration, the cleaning gas G can be injected into the combustion chamber 103 from the nozzle 21a of the deactivated valve of the fossil fuel injection valve 1 and the alternative fuel injection valve 2, without stopping the operation of the marine internal combustion engine 100. Therefore, the inside of the nozzle 21, which is exposed to the high-temperature environment of the combustion chamber 103, such as the nozzle 21a, which may generate sludge, and the internal passages, which may generate coking, can be cleaned by injecting the cleaning gas G. This makes it possible to prevent deposits such as sludge and coking from forming on the nozzle 21.

[0090] Furthermore, in the fuel injection device 10 according to the first embodiment of the present invention, it is determined whether or not the stop valve is the alternative fuel injection valve 2 based on the operation mode of the marine internal combustion engine 100, and if the stop valve is the alternative fuel injection valve 2 (i.e., if the alternative fuel injection valve 2 is in a stop state), the in-cylinder pressure P S is the gas pressure P G The cleaning gas G is injected from the nozzle 21 a of the nozzle 21 into the idle alternative fuel injection valve 2 at a timing when the timing is less than 1 / 2 of the predetermined time. Therefore, the inside of the nozzle of the idle alternative fuel injection valve 2 can be efficiently cleaned by the injection of the cleaning gas G in accordance with the operation mode of the marine internal combustion engine 100.

[0091] Furthermore, in the fuel injection device 10 according to the first embodiment of the present invention, it is determined whether or not the stop valve is the fossil fuel injection valve 1 based on the operation mode of the marine internal combustion engine 100, and if the stop valve is the fossil fuel injection valve 1 (i.e., if the fossil fuel injection valve 1 is in a stop state), the in-cylinder pressure P S is the gas pressure P G The cleaning gas G is injected from the nozzle 21a of the nozzle 21 into the fossil fuel injector 1 in the stopped state at a timing when the cleaning gas G is less than 1 / 2 of the injection port 21a of the nozzle 21. Therefore, the inside of the nozzle of the fossil fuel injector 1 in the stopped state can be efficiently cleaned by the injection of the cleaning gas G in accordance with the operation mode of the marine internal combustion engine 100.

[0092] In the fuel injection device 10 according to the first embodiment of the present invention, the cylinder pressure P S is the gas pressure P G At the timing when the valve opening pressure P V is the cylinder pressure P S Higher gas pressure than P G The valve opening pressure adjusting unit 30 is operated so that the pressure is within a range less than 1 / 2 of the pressure in the stop valve 100. Therefore, the injection of the cleaning gas G from the stop valve 100 is not hindered, and the backflow of gas from the combustion chamber 103 of the marine internal combustion engine 100 into the stop valve 100 can be reliably prevented.

[0093] In the fuel injection device 10 according to the first embodiment of the present invention, the in-cylinder pressure P S is the gas pressure P G Therefore, it is determined whether the cylinder pressure P S is the gas pressure P G It is possible to grasp the timing at which the in-cylinder pressure P S is the gas pressure P G Since the inside of the nozzle of the stop valve can be cleaned by injecting the cleaning gas G within a period of time that is less than 100 seconds, the efficiency of cleaning the inside of the nozzle by injecting the cleaning gas G can be improved.

[0094] In the fuel injection device 10 according to the first embodiment of the present invention, the valve opening pressure adjusting unit 30 includes a biasing spring 31 that biases the needle valve 26 in the direction of closing the nozzle hole 21a of the nozzle 21, and a piston unit 33 that acts on the biasing spring 31 by utilizing the pressure of the working fluid E. V The gas pressure P G In such a valve opening pressure adjusting section 30, the piston section 33 applies a force (resistance force) to the biasing spring 31 in a direction against the biasing force due to the pressure of the working fluid E, thereby adjusting the valve opening pressure P V The gas pressure P G Therefore, there is no need to replace the fossil fuel injector 1 and the alternative fuel injector 2, and the valve opening pressure P V The gas pressure P G or gas pressure P G Can be adjusted to less than.

[0095] (Embodiment 2) Next, the configuration of a fuel injection device according to a second embodiment of the present invention will be described. Fig. 7 is a block diagram showing an example of the configuration of a fuel injection device according to the second embodiment of the present invention. As shown in Fig. 7, a fuel injection device 10A according to the second embodiment includes a fossil fuel injection valve 1A instead of the fossil fuel injection valve 1 of the fuel injection device 10 according to the first embodiment described above, an alternative fuel injection valve 2A instead of the alternative fuel injection valve 2, and a control unit 7A instead of the control unit 7. The other configurations are the same as those of the first embodiment, and the same components are assigned the same reference numerals.

[0096] The fossil fuel injector 1A has an opening pressure P V The alternative fuel injection valve 2A has the same configuration as the fossil fuel injection valve 1 of the first embodiment described above, except that the configuration for adjusting the valve opening pressure P is different from that of the valve opening pressure adjusting unit 30 shown in FIG. V7, the fossil fuel injection valve 1A and the alternative fuel injection valve 2A are provided in a cylinder 101 of a marine internal combustion engine 100 in the same manner as the fossil fuel injection valve 1 and the alternative fuel injection valve 2 in the first embodiment described above, except that the configuration for adjusting the valve opening pressure is different from the valve opening pressure adjusting unit 30 shown in Fig. 2. As shown in Fig. 7, the fossil fuel injection valve 1A and the alternative fuel injection valve 2A are provided in a cylinder 101 of a marine internal combustion engine 100 in the same manner as the fossil fuel injection valve 1 and the alternative fuel injection valve 2 in the first embodiment described above.

[0097] The function of the control unit 7A is to control the valve opening pressure P of the fossil fuel injection valve 1A and the alternative fuel injection valve 2A. V Set to fuel injection pressure or gas pressure P G The control of the working fluid injecting unit 4 required to adjust the working fluid pressure to less than 1000 kJ / s is different from that of the control unit 7 of the above-described embodiment 1. The control unit 7A has the same control functions as the control unit 7 of embodiment 1 except for the control of the working fluid injecting unit 4.

[0098] (Configuration of fuel injection valve) Next, the configuration of the fuel injection valve included in the fuel injection device 10A according to the second embodiment of the present invention will be described. As shown in Fig. 7, the fuel injection device 10A includes a fossil fuel injection valve 1A and an alternative fuel injection valve 2A as multiple fuel injection valves provided in one cylinder 101 of a marine internal combustion engine 100. Below, the configuration of the fossil fuel injection valve 1A and the alternative fuel injection valve 2A will be described in detail, taking the alternative fuel injection valve 2A as an example.

[0099] Fig. 8 is a cross-sectional schematic view showing one configuration example of an alternative fuel injection valve according to embodiment 2 of the present invention. For convenience of explanation, in Fig. 8, the fuel injection side of the alternative fuel injection valve 2A is referred to as the front end side, and the side opposite to the fuel injection side is referred to as the rear end side.

[0100] 8, the alternative fuel injection valve 2A has a valve opening pressure adjusting section 30A instead of the valve opening pressure adjusting section 30 of the alternative fuel injection valve 2 according to the above-described first embodiment. The valve opening pressure adjusting section 30A has a piston section 33A, a receiving section 37, and a lid section 38 instead of the adjusting screw 32 and piston section 33 of the valve opening pressure adjusting section 30 according to the above-described embodiment, a fluid passage 38a instead of the fluid passage 23c, and an operating chamber 36A instead of the operating chamber 36. The other configuration of this valve opening pressure adjusting section 30A is the same as that of the valve opening pressure adjusting section 30 of the first embodiment, and the same components are designated by the same reference numerals.

[0101] The piston portion 33A is an example of an operating portion that uses the pressure of the working fluid E to strengthen the biasing force of the biasing spring 31. Specifically, as shown in FIG. 8 , the piston portion 33A is slidably housed inside the housing portion 35 while receiving the rear end of the biasing spring 31. A working chamber 36A is formed at the rear end of the housing portion 35, which is a space surrounded by the rear end of the piston portion 33A, the tip end of the lid portion 38, and the inner wall surface of the housing portion 35. The piston portion 33A uses the pressure of the working fluid E injected into the working chamber 36A from the flow pipe 18b of the working fluid injection portion 4 through the fluid passage 38a to apply a force (hereinafter referred to as an additional force) that strengthens the biasing force of the biasing spring 31 to the biasing spring 31. The direction in which the additional force acts on the biasing spring 31 is the same as the direction in which the biasing spring 31 biases the needle valve 26 (the direction of the biasing force). In the second embodiment, the valve-opening pressure P of the needle valve 26 is V The piston portion 33A applies additional force to the biasing spring 31, and the biasing force of the biasing spring 31 is strengthened, so that the pressure is set to the target fuel injection pressure.

[0102] Furthermore, when the pressure of the working fluid E is reduced due to, for example, the removal of the working fluid E from the working chamber 36A, the piston portion 33A weakens the additional force and releases the strengthening of the biasing force of the biasing spring 31. By releasing the strengthening of the biasing force, the piston portion 33A reduces the valve opening pressure P V The pressure of the cleaning gas G (gas pressure P G From the viewpoint of preventing the backflow of gas from the combustion chamber of the marine internal combustion engine 100 into the nozzle 21, the valve opening pressure P Vis the cylinder pressure P of the marine internal combustion engine 100 S Higher gas pressure than P G It is preferable that the pressure be adjusted to a value lower than the pressure at which the pressure is increased.

[0103] The receiving portion 37 receives the biasing force of the biasing spring 31. More specifically, as shown in FIG. 8, the receiving portion 37 is housed inside the housing portion 35 with the tip of the biasing spring 31 being received therein. Also, as shown in FIG. 8, the push rod 27 is fixed to the receiving portion 37. The receiving portion 37 transmits the biasing force of the biasing spring 31 to the push rod 27. The biasing force of the biasing spring 31 is transmitted to the needle valve 26 via the receiving portion 37 and the push rod 27, thereby generating a valve opening pressure P V is converted to

[0104] As shown in Fig. 8, the lid portion 38 closes the accommodation portion 35 that accommodates the biasing spring 31, the piston portion 33A, and the receiving portion 37, and is attached to the rear end portion of the injection valve body 23. As shown in Fig. 8, the lid portion 38 has a fluid passage 38a therein for circulating the working fluid E. This fluid passage 38a communicates with the circulation pipe 18b joined to the rear end portion of the lid portion 38. The working fluid E circulates between the circulation pipe 18b and the working chamber 36A via this fluid passage 38a.

[0105] Although not specifically shown, the configuration of the fossil fuel injector 1A is similar to the configuration of the alternative fuel injector 2A shown in FIG. 8, except that the target of injection is a fossil fuel.

[0106] (Adjustment of valve opening pressure) Next, the valve opening pressure P of the needle valve 26 in each of the fossil fuel injector 1A and the alternative fuel injector 2A described above is calculated. V 9 is a diagram for explaining the adjustment of the needle valve opening pressure in the second embodiment of the present invention. In FIG. 9, an enlarged cross-sectional view of the alternative fuel injection valve 2A is shown in schematic form. Below, the adjustment of the valve opening pressure P of the needle valve 26 will be described using the alternative fuel injection valve 2A as an example. V The adjustment of the valve opening pressure P V The adjustment of the valve opening pressure P of the needle valve 26 in the fossil fuel injector 1A is V This is similar to the adjustment of

[0107] In the second embodiment, the valve opening pressure P V is adjusted by the valve-opening pressure adjusting unit 30A described above. More specifically, in state S1 shown in Fig. 9 , working fluid E is injected into the working chamber 36A of the alternative fuel injection valve 2A from the flow pipe 18b of the working fluid injecting unit 4 via the fluid passage 38a. In this case, in the valve-opening pressure adjusting unit 30A, the piston portion 33A utilizes the pressure of the working fluid E in the working chamber 36A to compress the biasing spring 31 in a direction toward the tip side of the alternative fuel injection valve 2A (the direction of arrow Y3 in Fig. 9 ). As a result, the piston portion 33A applies an additional force to the biasing spring 31 in the same direction as the biasing force of the biasing spring 31, while increasing the compression amount of the biasing spring 31, thereby strengthening the biasing force of the biasing spring 31. The direction of the biasing force of the biasing spring 31 is the direction in which the biasing spring 31 biases the needle valve 26 (see FIG. 8) toward the tip side of the alternative fuel injection valve 2A, and is the direction in which the nozzle hole 21a of the nozzle 21 described above is closed (the direction of the arrow Y1 in FIG. 9).

[0108] In the above state S1, the valve opening pressure P V is adjusted to the target fuel injection pressure by the resultant force of the biasing spring 31 strengthened by the piston portion 33A using the pressure of the working fluid E, i.e., the original biasing force of the biasing spring 31 before being strengthened by the piston portion 33A and the additional force of the piston portion 33A. The fuel injection pressure is the same as in the first embodiment described above. That is, the valve opening pressure P V is smaller than the pressure of the alternative fuel in the fuel passage 51, which is pressurized by the pump 112, and the pressure of the cleaning gas G injected into the cleaning gas passage 52 (see FIG. 8) of the alternative fuel injection valve 2A (gas pressure P G ) is extremely large compared to

[0109] In addition, the valve opening pressure P V When the piston portion 33A releases the increased biasing force of the biasing spring 31, the gas pressure P G9, the working fluid E is removed from the working chamber 36A through the fluid passage 38a and the flow pipe 18b to the outside of the alternative fuel injection valve 2A. In this case, the pressure acting on the piston portion 33A from the working fluid E decreases, and the force with which the piston portion 33 compresses (presses) the biasing spring 31 weakens. The biasing spring 31 pushes back the piston portion 33A in the direction toward the rear end side of the alternative fuel injection valve 2A (the direction of the arrow Y4 in FIG. 9). As a result, the piston portion 33A releases the strengthened biasing force of the biasing spring 31, and the biasing force of the biasing spring 31 returns to its original biasing force before being strengthened. In this state S2, the valve-opening pressure P V is set by the original biasing force of the biasing spring 31. In this way, the piston portion 33A is V The gas pressure P G Less than (preferably, the cylinder pressure P S Higher gas pressure than P G The pressure can be reduced to a range below which the pressure is less than 1000 kJ / cm2.

[0110] The valve opening pressure adjusting unit 30A changes to the above state S1 or state S2 as appropriate, thereby adjusting the valve opening pressure P V Set the fuel injection pressure to the desired level or set the gas pressure P G The working fluid E may be returned from the working chamber 36A to the working fluid injector 4 via the fluid passage 38a as the piston portion 33A is pushed back by the biasing spring 31, or may be discharged to the outside of the alternative fuel injection valve 2A via a drain path (not shown) formed in the alternative fuel injection valve 2A.

[0111] (How to clean a fuel injection valve) Next, a method for cleaning a fuel injection valve by a fuel injection device 10A according to a second embodiment of the present invention will be described. The fuel injection device 10A, similar to the first embodiment described above, sequentially performs the processes of steps S101 to S105 (see FIG. 6) to clean the nozzles of the deactivated valves of the fossil fuel injection valve 1A and the alternative fuel injection valve 2A with cleaning gas G. That is, in the second embodiment, among the steps S101 to S105, the valve opening pressure P VThe processes in steps S103 and S105 for adjusting the value are different from those in the first embodiment.

[0112] In detail, in step S103 of the second embodiment, the fuel injection device 10A injects the working fluid E into the fuel injection valve that is not inactive (hereinafter referred to as the non-inactive valve) out of the fossil fuel injection valve 1A and the alternative fuel injection valve 2A, and increases the valve opening pressure P V is set to the fuel injection pressure, and the injection of the working fluid E into the stop valve is stopped to set the valve opening pressure P V The gas pressure P G At this time, the control unit 7A controls the working fluid injecting unit 4 so as to inject the working fluid E into the non-stop valves and not to inject the working fluid E into the stop valves.

[0113] For example, if the fossil fuel injector 1A is a deactivated valve and the alternative fuel injector 2A is a non-deactivated valve, the control unit 7A controls the working fluid source 16 and the second control valve 19 to inject the working fluid E into the working chamber 36A of the non-deactivated alternative fuel injector 2A via the flow pipe 18b and to recover the working fluid E from the working chamber 36A of the deactivated fossil fuel injector 1A via the flow pipe 18a. Thereafter, the control unit 7A continues to inject the working fluid E into the working chamber 36A of the non-deactivated alternative fuel injector 2A and controls the working fluid source 16 and the second control valve 19 to close the flow pipe 18a leading to the deactivated fossil fuel injector 1A.

[0114] As a result, the working fluid E pressurized by the working fluid injector 4 is injected into the working chamber 36A of the alternative fuel injection valve 2A that is not in a resting state. V is set to the fuel injection pressure by the action of the piston portion 33A (strengthening of the biasing force of the biasing spring 31) utilizing the pressure of this working fluid E. Also, in the fossil fuel injection valve 1A in the resting state, the pressure of the working fluid E injected into the working chamber 36A drops, and this causes the strengthening of the biasing force of the biasing spring 31 by the piston portion 33A to be released. The valve opening pressure P V By canceling the strengthening of the biasing force, the gas pressure P GThe valve opening pressure P V is larger than the pressure of the fossil fuel remaining without being pressurized in the fuel passage 51 of the fossil fuel injector 1A. The remaining fossil fuel may be removed from the fossil fuel injector 1A in advance before the injection of the cleaning gas G.

[0115] Furthermore, when the alternative fuel injector 2A is a deactivated valve and the fossil fuel injector 1A is a non-deactivated valve, the control unit 7A controls the working fluid source 16 and the second control valve 19 to inject the working fluid E into the working chamber 36A of the non-deactivated fossil fuel injector 1A via the flow pipe 18a and to recover the working fluid E from the working chamber 36A of the deactivated alternative fuel injector 2A via the flow pipe 18b. Thereafter, the control unit 7A continues to inject the working fluid E into the working chamber 36A of the non-deactivated fossil fuel injector 1A and controls the working fluid source 16 and the second control valve 19 to close the flow pipe 18b leading to the deactivated alternative fuel injector 2A.

[0116] As a result, the working fluid E pressurized by the working fluid injector 4 is injected into the working chamber 36A of the non-stop fossil fuel injector 1A. V is set to the fuel injection pressure by the action of the piston portion 33A (strengthening of the biasing force of the biasing spring 31) utilizing the pressure of this working fluid E. Also, in the alternative fuel injection valve 2A in the stopped state, the pressure of the working fluid E injected into the working chamber 36A drops, and this causes the strengthening of the biasing force of the biasing spring 31 by the piston portion 33A to be released. The valve opening pressure P V By canceling the strengthening of the biasing force, the gas pressure P G The valve opening pressure P V is larger than the pressure of the alternative fuel that is not pressurized and remains in the fuel passage 51 of this alternative fuel injection valve 2A. Note that the remaining alternative fuel may be removed in advance from the alternative fuel injection valve 2A before the injection of the cleaning gas G.

[0117] Regardless of whether the fossil fuel injection valve 1A or the alternative fuel injection valve 2A is a deactivation valve, the control unit 7A controls the in-cylinder pressure P S is the gas pressure P G At the timing above, the opening pressure P V is the cylinder pressure P S The pressure of the cleaning gas G (gas pressure P G It is preferable to operate the valve opening pressure adjusting section 30A of the corresponding stop valve so that the pressure is within a range of less than 1 / 2.

[0118] In step S105 of the second embodiment, the fuel injection device 10A calculates the valve opening pressure P V is set as the fuel injection pressure. At this time, the control unit 7A controls the working fluid injection unit 4 to continue or resume the injection of the working fluid E into each of the non-stopped fossil fuel injection valve 1A and the alternative fuel injection valve 2A. As a result, the second control valve 19 brings the flow pipe 17 and the flow pipes 18a, 18b into a state of communication. The working fluid E is injected from the working fluid source 16 through the flow pipe 17 and the like into each of the working chambers 36A of the non-stopped fossil fuel injection valve 1A and the alternative fuel injection valve 2A. In each of the fossil fuel injection valve 1A and the alternative fuel injection valve 2A, the valve opening pressure P V is set to the fuel injection pressure by the action of the piston portion 33A (strengthening of the biasing force of the biasing spring 31) utilizing the pressure of the working fluid E in the working chamber 36A.

[0119] As described above, in the fuel injection device 10A according to the second embodiment of the present invention, the valve-opening pressure adjusting unit 30A includes the biasing spring 31 that biases the needle valve 26 in the direction of closing the nozzle hole 21a of the nozzle 21, and the piston unit 33A that strengthens the biasing force of the biasing spring 31 by utilizing the pressure of the working fluid E. V The piston portion 33A is biased by the biasing force of the biasing spring 31 to increase the gas pressure P G The piston portion 33A releases the increased biasing force of the biasing spring 31, thereby increasing the valve opening pressure P V The gas pressure PG The other aspects are the same as those of the first embodiment. Therefore, the same effects as those of the first embodiment can be obtained, and the valve opening pressure P V With a simpler configuration, the gas pressure P G or gas pressure P G Can be adjusted to less than.

[0120] (Embodiment 3) Next, the configuration of a fuel injection device according to a third embodiment of the present invention will be described. FIG. 10 is a block diagram showing an example of the configuration of a fuel injection device according to the third embodiment of the present invention. As shown in FIG. 10, the fuel injection device 10B according to the third embodiment further includes a fossil fuel injector 1B in addition to the fossil fuel injector 1 and the alternative fuel injector 2 of the fuel injection device 10 according to the first embodiment described above. It also includes a cleansing gas injector 3B instead of the cleansing gas injector 3, a working fluid injector 4B instead of the working fluid injector 4, and a control unit 7B instead of the control unit 7. The cleansing gas injector 3B also includes a first control valve 15B instead of the first control valve 15 of the cleansing gas injector 3 in the first embodiment described above, and further includes a flow pipe 13c and a check valve 14c leading to the fossil fuel injector 1B. The working fluid injector 4B also includes a second control valve 19B instead of the second control valve 19 of the working fluid injector 4 in the first embodiment described above, and further includes a flow pipe 18c leading to the fossil fuel injector 1B. The other configurations are the same as those in the first embodiment, and the same components are designated by the same reference numerals.

[0121] The fossil fuel injector 1B is a fuel injector that injects fossil fuel into the combustion chamber of the marine internal combustion engine 100, and is provided in the cylinder 101 of the marine internal combustion engine 100 in addition to the fossil fuel injector 1 and the alternative fuel injector 2, as shown in FIG. 10. A fuel pipe 113B for pumping fossil fuel from a fossil fuel pump 111 is connected to this fossil fuel injector 1B, as shown in FIG. 10. For example, of these fossil fuel injectors 1, 1B, one fossil fuel injector 1 (first fossil fuel injector) is designed so that the marine internal combustion engine 100 can operate at 100% load by injecting fossil fuel alone. The other fossil fuel injector 1B (second fossil fuel injector) is designed so that the marine internal combustion engine 100 can operate at 100% load by injecting fossil fuel in cooperation with the fossil fuel injector 1. Although not particularly shown, the configuration of the fossil fuel injector 1B is similar to the configuration of the fossil fuel injector 1 described above.

[0122] The cleansing gas injection unit 3B injects cleansing gas G, which cleans the nozzles of the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, into each of these three fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2. In detail, the flow pipe 13c is a pipe (gas pipe) for circulating the cleansing gas G delivered from the cleansing gas source 11, and as shown in FIG. 10, is arranged to communicate between the first control valve 15B and the fossil fuel injection valve 1B. In the cleansing gas injection unit 3B, the three flow pipes 13a to 13c function as branch pipes branching from the flow pipe 12 via the first control valve 15B. As shown in FIG. 10, the check valve 14c is provided in the flow pipe 13c that leads to the fossil fuel injection valve 1B. The check valve 14c allows the cleansing gas G flowing through this flow pipe 13c to flow toward the fossil fuel injection valve 1B and prevents the cleansing gas G from flowing back.

[0123] The first control valve 15B is configured by a branch valve or the like, and can selectively switch communication between the flow pipe 12 and the flow pipes 13a to 13c by adjusting the valve opening. In detail, the cleansing gas injection unit 3B injects cleansing gas G into the fossil fuel injection valves 1, 1B and the deactivated valves among the alternative fuel injection valves 2. At this time, the first control valve 15B adjusts the valve opening based on the control of the control unit 7B, thereby connecting one of the three flow pipes 13a to 13c that leads to the deactivated valve with the flow pipe 12 on the cleansing gas source 11 side. The cleansing gas G is injected from the deactivated valve into the combustion chamber of the marine internal combustion engine 100, thereby cleansing the inside of the nozzle of the deactivated valve.

[0124] For example, when cleaning gas G is injected from cleaning gas source 11 only into fossil fuel injector 1, first control valve 15B closes flow pipes 13b and 13c and connects flow pipe 13a to flow pipe 12. When cleaning gas G is injected from cleaning gas source 11 only into fossil fuel injector 1B, first control valve 15B closes flow pipes 13a and 13b and connects flow pipe 13c to flow pipe 12. When cleaning gas G is injected from cleaning gas source 11 only into alternative fuel injector 2, first control valve 15B closes flow pipes 13a and 13c and connects flow pipe 13b to flow pipe 12.

[0125] Furthermore, when cleaning gas G is injected from cleaning gas source 11 into both fossil fuel injector 1 and alternative fuel injector 2, first control valve 15B closes flow pipe 13c and communicates flow pipes 13a and 13b with flow pipe 12. When cleaning gas G is injected from cleaning gas source 11 into both fossil fuel injector 1B and alternative fuel injector 2, first control valve 15B closes flow pipe 13a and communicates flow pipes 13b and 13c with flow pipe 12. When cleaning gas G is injected from cleaning gas source 11 into both fossil fuel injector 1 and 1B, first control valve 15B closes flow pipe 13b and communicates flow pipes 13a and 13c with flow pipe 12. Furthermore, when the cleaning gas G is not injected into both the fossil fuel injectors 1, 1B and the alternative fuel injector 2, the first control valve 15B blocks communication between the flow pipes 13a to 13c and the flow pipe 12 described above.

[0126] The working fluid injection unit 4B injects working fluid E, which is used to inject cleaning gas G from the nozzle opening into the pause valve, into each of the fossil fuel injectors 1, 1B and the alternative fuel injector 2. In detail, the flow pipe 18c is a pipe for circulating the working fluid E delivered from the working fluid source 16 to the fossil fuel injector 1B, and as shown in FIG. 10, is arranged to communicate between the second control valve 19 and the fossil fuel injector 1B. In the working fluid injection unit 4B, the three flow pipes 18a to 18c function as branch pipes branching from the flow pipe 17 via the second control valve 19.

[0127] The second control valve 19B is configured by a branch valve or the like, and can selectively switch communication between the circulation pipe 17 and the circulation pipes 18a to 18c by adjusting the valve opening. In detail, the working fluid injection unit 4B injects the working fluid E into the deactivated valves among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, and stops the injection of the working fluid E into the non-activated valves. At this time, the second control valve 19B adjusts the valve opening based on the control of the control unit 7B, thereby connecting the circulation pipe leading to the deactivated valve among the three circulation pipes 18a to 18c with the circulation pipe 17 on the working fluid source 16 side, and blocking communication between the circulation pipe leading to the non-activated valve and the circulation pipe 17.

[0128] For example, when the working fluid E is injected from the working fluid source 16 only into the fossil fuel injector 1, the second control valve 19B communicates between the flow pipe 18a and the flow pipe 17 and blocks the communication between the flow pipes 18b and 18c and the flow pipe 17. When the working fluid E is injected from the working fluid source 16 only into the fossil fuel injector 1B, the second control valve 19B communicates between the flow pipe 18c and the flow pipe 17 and blocks the communication between the flow pipes 18a and 18b and the flow pipe 17. When the working fluid E is injected from the working fluid source 16 only into the alternative fuel injector 2, the second control valve 19B communicates between the flow pipe 18b and the flow pipe 17 and blocks the communication between the flow pipes 18a and 18c and the flow pipe 17.

[0129] Furthermore, when the working fluid E is injected from the working fluid source 16 into the fossil fuel injector 1 and the alternative fuel injector 2, the second control valve 19B closes the flow pipe 18c and communicates the flow pipes 18a, 18b with the flow pipe 17. When the working fluid E is injected from the working fluid source 16 into the fossil fuel injector 1B and the alternative fuel injector 2, the second control valve 19B closes the flow pipe 18a and communicates the flow pipes 18b, 18c with the flow pipe 17. When the working fluid E is injected from the working fluid source 16 into the fossil fuel injectors 1, 1B, the second control valve 19B closes the flow pipe 18b and communicates the flow pipes 18a, 18c with the flow pipe 17.

[0130] Of the fossil fuel injectors 1, 1B and the alternative fuel injector 2, the fuel injector (stopped valve) into which the working fluid E is injected has a valve opening pressure P V is the pressure of the cleaning gas G (gas pressure P G ) (preferably less than the cylinder pressure P S Higher gas pressure than P G In the fuel injection valve (non-stopped valve) in which the injection of the working fluid E is stopped, the valve opening pressure P V is adjusted to the desired fuel injection pressure.

[0131] The control unit 7B controls the injection timing of the cleaning gas G from the nozzle opening for the fossil fuel injection valves 1, 1B and the deactivated valves among the alternative fuel injection valves 2. In detail, the control unit 7B controls the injection timing of the cleaning gas G from the nozzle opening for the deactivated valves among the fossil fuel injection valves 1, 1B and the alternative fuel injection valves 2. S is the gas pressure P G The control unit 7B controls the valve apertures of the first control valve 15B and the second control valve 19B at a timing when the valve apertures are less than 1 / 2 of the predetermined value, thereby causing the pause valve to inject cleaning gas G from the nozzle opening. Furthermore, the control unit 7B determines the operation mode of the marine internal combustion engine 100 based on an input signal from the operation unit 120 of the marine internal combustion engine 100. The functions of the control unit 7B differ from those of the control unit 7 of the first embodiment in the control of the valve apertures of the first control valve 15B and the second control valve 19B and the determination of the operation mode of the marine internal combustion engine 100. Other than these, the control unit 7B has the same control functions as the control unit 7 of the first embodiment.

[0132] (Operating modes of marine internal combustion engines) Next, an explanation will be given of the operating modes of the marine internal combustion engine 100 according to the third embodiment of the present invention. The marine internal combustion engine 100 is a multi-fuel engine that operates by combusting at least one of the fossil fuels injected from the fossil fuel injection valves 1, 1B and the alternative fuel injected from the alternative fuel injection valve 2. There are multiple operating modes for such a marine internal combustion engine 100 depending on the type of fuel to be combusted.

[0133] Fig. 11 is a diagram showing an example of operation modes of a marine internal combustion engine according to the third embodiment of the present invention. As shown in Fig. 11, operation modes of the marine internal combustion engine 100 include, for example, a first multi-fuel operation mode, a second multi-fuel operation mode, a first mono-fuel operation mode, a second mono-fuel operation mode, and a third mono-fuel operation mode. In Fig. 11, the first fossil fuel injector refers to the fossil fuel injector 1, and the second fossil fuel injector refers to the fossil fuel injector 1B.

[0134] The first multi-fuel operation mode is an example of an operation mode in which the marine internal combustion engine 100 operates by multi-fueling fossil fuel and alternative fuel. In the first multi-fuel operation mode, in each cycle period, fossil fuel is injected as pilot fuel from the fossil fuel injector 1 into the combustion chamber 103. Following this pilot fuel, alternative fuel is injected into the combustion chamber 103 from the alternative fuel injector 2. Following this alternative fuel, fossil fuel is injected as post-fuel from the fossil fuel injector 1B into the combustion chamber 103. The post-fuel is injected and ignited in the latter half of the injection of the alternative fuel, which is the main fuel, to ensure sufficient combustion of the alternative fuel. The marine internal combustion engine 100 operates by burning (mixing) the pilot fuel, alternative fuel, and post-fuel. In this first multi-fuel operation mode, as shown in Fig. 11, fossil fuel injector 1 injects pilot fuel, alternative fuel injector 2 injects alternative fuel, and fossil fuel injector 1B injects post fuel for each cycle period, so there are no deactivated valves that suspend fuel injection during one cycle period among fossil fuel injector 1, 1B, and alternative fuel injector 2. In other words, all of these are non-deactivated valves.

[0135] The second multi-fuel operation mode is the same as the multi-fuel operation mode in the first embodiment described above (see FIG. 5), except that post fuel is not injected from the fossil fuel injector 1B. In this second multi-fuel operation mode, the fossil fuel injector 1 injects pilot fuel, the alternative fuel injector 2 injects alternative fuel, and the fossil fuel injector 1B pauses injection of fossil fuel for each cycle period, as shown in FIG. 11. Therefore, of the fossil fuel injectors 1, 1B, and the alternative fuel injector 2, the fossil fuel injector 1B is a paused valve, and the fossil fuel injector 1 and the alternative fuel injector 2 are non-paused valves.

[0136] The first dedicated fuel operation mode is the same as the first dedicated fuel operation mode (see FIG. 5) in the first embodiment described above, except that fossil fuel is not injected from the fossil fuel injector 1B. In such a first dedicated fuel operation mode, as shown in FIG. 11, the fossil fuel injector 1 injects fossil fuel for each cycle period, and the alternative fuel injector 2 and the fossil fuel injector 1B pause fuel injection. Therefore, of the fossil fuel injectors 1, 1B and the alternative fuel injector 2, the alternative fuel injector 2 and the fossil fuel injector 1B are paused valves, and the fossil fuel injector 1 is a non-paused valve.

[0137] The second dedicated fuel operation mode is the same as the second dedicated fuel operation mode (see FIG. 5) in the first embodiment described above, except that fossil fuel is not injected from fossil fuel injector 1B. In such a second dedicated fuel operation mode, as shown in FIG. 11, the alternative fuel injector 2 injects alternative fuel for each cycle period, and the fossil fuel injectors 1 and 1B pause fuel injection. Therefore, of the fossil fuel injectors 1 and 1B and the alternative fuel injector 2, the fossil fuel injector 1 and 1B are paused valves, and the alternative fuel injector 2 is a non-paused valve.

[0138] The third exclusive-fuel operation mode is an example of an operation mode in which the marine internal combustion engine 100 operates by burning only fossil fuel. In the third exclusive-fuel operation mode, fossil fuel is injected from the fossil fuel injector 1 into the combustion chamber 103 for each cycle period, and subsequently, fossil fuel is injected from the fossil fuel injector 1B into the combustion chamber 103. The marine internal combustion engine 100 operates by burning these fossil fuels (exclusive combustion). In this third exclusive-fuel operation mode, as shown in FIG. 11 , the fossil fuel injectors 1 and 1B sequentially inject fossil fuel for each cycle period. Therefore, of the fossil fuel injectors 1 and 1B and the alternative fuel injection valve 2, the alternative fuel injection valve 2 is a deactivated valve, and the fossil fuel injection valves 1 and 1B are non-deactivated valves.

[0139] (How to clean a fuel injection valve) Next, a description will be given of a method for cleaning a fuel injection valve by a fuel injection device 10B according to the third embodiment of the present invention. The fuel injection device 10B sequentially performs the processes of steps S101 to S105 (see FIG. 6) in substantially the same manner as in the first embodiment described above, thereby cleaning the nozzles of the fossil fuel injection valves 1, 1B and the inactive valves of the alternative fuel injection valves 2 with cleaning gas G.

[0140] More specifically, in step S101 of the third embodiment, the fuel injection device 10B determines whether or not a deactivated valve is present among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2 provided in the cylinder 101 of the marine internal combustion engine 100. At this time, the control unit 7B acquires an operation mode signal from the operation unit 120 in the same manner as in the first embodiment, and recognizes the current operation mode of the marine internal combustion engine 100 based on the acquired operation mode signal. Based on the recognized operation mode, the control unit 7B determines whether or not a deactivated valve is present among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, and if a deactivated valve is present, which of the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2 is the deactivated valve.

[0141] For example, as shown in Fig. 11, the operating modes of the marine internal combustion engine 100 in the third embodiment include a first multi-fuel operation mode, a second multi-fuel operation mode, a first mono-fuel operation mode, a second mono-fuel operation mode, and a third mono-fuel operation mode. Based on the above-mentioned operation mode signal, the control unit 7B determines whether the operating mode of the marine internal combustion engine 100 is the first multi-fuel operation mode, the second multi-fuel operation mode, the first mono-fuel operation mode, the second mono-fuel operation mode, or the third mono-fuel operation mode. When the operating mode of the marine internal combustion engine 100 is the first multi-fuel operation mode, the control unit 7B determines that there is no deactivated valve among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2. When the operating mode of the marine internal combustion engine 100 is the second multi-fuel operation mode, the control unit 7B determines that there is a deactivated valve among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, and that the deactivated valve is the fossil fuel injection valve 1B. When the operation mode of the marine internal combustion engine 100 is the first mono-fuel operation mode, the control unit 7B determines that there are deactivated valves among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, and that these deactivated valves are the alternative fuel injection valve 2 and the fossil fuel injection valve 1B. When the operation mode of the marine internal combustion engine 100 is the second mono-fuel operation mode, the control unit 7B determines that there are deactivated valves among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, and that these deactivated valves are the fossil fuel injection valves 1, 1B. When the operation mode of the marine internal combustion engine 100 is the third mono-fuel operation mode, the control unit 7B determines that there is a deactivated valve among the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, and that these deactivated valves are the alternative fuel injection valve 2.

[0142] In step S102 of the third embodiment, the same process as in the first embodiment is executed. In addition, steps S103 and S104 of the third embodiment are the same as those of the first embodiment, except that the pause valves are one or two of the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, as described above. In this case, in step S103, the control unit 7B controls the valve aperture of the second control valve 19B so as to open the circulation pipes leading to the pause valves among the circulation pipes 18a to 18c of the working fluid injection unit 4 and close the circulation pipes leading to the non-pause valves. In step S104, the control unit 7B controls the valve aperture of the first control valve 15B so as to open the circulation pipes leading to the pause valves among the circulation pipes 13a to 13c of the cleaning gas injection unit 3 and close the circulation pipes leading to the non-pause valves.

[0143] Furthermore, in step S105 of the third embodiment, the same processing as in the first embodiment is executed, except that the target fuel injection valves are the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2. At this time, the control unit 7B controls the valve opening degree of the second control valve 19B so as to close all of the flow pipes 18a to 18c of the working fluid injection unit 4.

[0144] As described above, in the fuel injection device 10B according to the third embodiment of the present invention, three valves, namely, the fossil fuel injection valves 1, 1B and the alternative fuel injection valve 2, are provided in the cylinder 101 of the marine internal combustion engine 100, and the cleansing gas G is injected into the combustion chamber 103 from the deactivation valve of these three fuel injection valves, with the rest being the same as in the first embodiment. Therefore, even when three fuel injection valves are provided in one cylinder 101, it is possible to enjoy the same effects as in the first embodiment described above.

[0145] In the above-described first to third embodiments, the crank angle θ of the marine internal combustion engine 100 is detected by the crank angle detection unit 6, and the in-cylinder pressure P SFor example, the fuel injection device according to the present invention may include an exhaust valve operation detection unit that detects the operation of the exhaust valve 104 of the marine internal combustion engine 100, and may calculate the in-cylinder pressure P based on the detected operation of the exhaust valve 104. S In this case, the control unit may derive the gas pressure P G The cylinder pressure P is larger than S When the exhaust valve 104 is open, the gas pressure P G The cylinder pressure P is smaller than S Alternatively, the fuel injection device according to the present invention may derive the in-cylinder pressure P S The cylinder pressure P S is the gas pressure P G The control unit may determine whether the value is less than the predetermined value.

[0146] In addition, in the above-described first to third embodiments, the fossil fuel injection valve and the alternative fuel injection valve are illustrated as having a single nozzle hole, but the present invention is not limited to this. For example, each of the fossil fuel injection valve and the alternative fuel injection valve may have multiple nozzle holes at the tip of the nozzle.

[0147] Furthermore, in the above-described first to third embodiments, a single cylinder is provided with multiple types of fuel injection valves, including one or two fossil fuel injection valves and one alternative fuel injection valve, but the present invention is not limited to this. For example, a single cylinder may be provided with two or more types of fuel injection valves, including at least a fossil fuel injection valve and an alternative fuel injection valve, and the number of each of the fossil fuel injection valve and the alternative fuel injection valve included in these two or more types of fuel injection valves may be one or two or more.

[0148] Furthermore, in the above-described first to third embodiments, a marine internal combustion engine is used as an example of a multi-fuel engine that operates using at least one of a fossil fuel and an alternative fuel, but the present invention is not limited to this. For example, the multi-fuel engine may be a diesel engine other than a marine engine, or an internal combustion engine other than a diesel engine.

[0149] Furthermore, the present invention is not limited to the above-described Embodiments 1 to 3, and also includes configurations in which the above-described components are appropriately combined (for example, a combination of Embodiments 2 and 3). In addition, all other embodiments, examples, operational techniques, etc. made by those skilled in the art based on the above-described Embodiments 1 to 3 are included in the scope of the present invention. [Explanation of symbols]

[0150] 1, 1A, 1B Fossil fuel injector 2, 2A alternative fuel injection valve 3, 3B Cleaning gas injection section 4, 4B Working fluid injection part 5 Pressure detection unit 6 Crank angle detector 7, 7A, 7B control section 10, 10A, 10B fuel injector 11 Cleaning gas source 12, 13a, 13b, 13c, 17, 18a, 18b, 18c flow pipe 14a, 14b, 14c check valves 15, 15B First control valve 16 Working fluid source 19, 19B Second control valve 21 nozzles 21a spout 21b Fuel storage section 21c Tip passage 22 Nozzle joint 22a Insertion hole 22b Fuel passage 22c Cleaning gas passage 23 Injection valve body 23a Fuel passage 23b Cleaning gas passage 23c Fluid passage 23d Insertion hole 24 Fastening part 25 Fuel receiving section 26 Needle valve 27 Push Stick 30, 30A valve opening pressure adjustment part 31 biasing spring 32 Adjustment screw 33, 33A Piston part 34 Rod-shaped part 35 Storage section 36, 36A operating chamber 37 Receiving part 38 Lid 38a Fluid passage 41 Needle valve housing 51 Fuel passage 52 Cleaning gas passage 100 Marine internal combustion engine 101 Cylinder 102 Piston 103 Combustion chamber 104 Exhaust valve 105 crank 106 Crankshaft 110 Propeller shaft 111 Fossil fuel pump 112 Pump 113, 113B, 114 Fuel pipe 120 Operation section A T Top dead center A B bottom dead center E Working fluid F fuel G Cleaning gas Y1~Y4 arrows

Claims

1. a fossil fuel injector for injecting a fossil fuel into a combustion chamber of a multi-fuel engine capable of operating using at least one of a fossil fuel and an alternative fuel; an alternative fuel injection valve that injects the alternative fuel into the combustion chamber of the multi-fuel engine; a cleaning gas injection unit that injects cleaning gas into a fuel injection valve that is in a stopped state and is stopping fuel injection during operation of the multi-fuel engine, out of the fossil fuel injection valve and the alternative fuel injection valve, to clean a nozzle of the fuel injection valve that is in a stopped state; a working fluid injection unit that injects a working fluid into each of the fossil fuel injection valve and the alternative fuel injection valve, for injecting the cleaning gas from the nozzle opening into the fuel injection valve in the inactive state; a control unit that controls the timing of injection of the cleaning gas from the nozzle outlet; Equipped with each of the fossil fuel injection valve and the alternative fuel injection valve includes the nozzle, a needle valve that opens and closes an injection port of the nozzle, and a valve opening pressure adjustment unit that adjusts the valve opening pressure of the needle valve by using the working fluid; the control unit determines whether or not an in-cylinder pressure of the multi-fuel engine is less than the pressure of the cleaning gas, and, at a timing when the in-cylinder pressure is less than the pressure of the cleaning gas, operates the valve opening pressure adjusting unit so that the valve opening pressure of the fuel injection valve in the stopped state decreases to less than the pressure of the cleaning gas, thereby causing the fuel injection valve in the stopped state to inject the cleaning gas from an injection port of the nozzle. A fuel injection device characterized by:

2. the control unit determines whether the fuel injection valve in the deactivated state is the alternative fuel injection valve based on an operation mode of the multi-fuel engine, and if the alternative fuel injection valve is in the deactivated state, causes the alternative fuel injection valve in the deactivated state to inject the cleaning gas from an injection port of the nozzle at a timing when the in-cylinder pressure is lower than the pressure of the cleaning gas.

2. The fuel injection system according to claim 1.

3. the control unit determines whether the fuel injection valve in the stopped state is the fossil fuel injection valve based on an operation mode of the multi-fuel engine, and if the fossil fuel injection valve is in the stopped state, injects the cleaning gas into the stopped fossil fuel injection valve from an injection port of the nozzle at a timing when the in-cylinder pressure is lower than the pressure of the cleaning gas.

2. The fuel injection system according to claim 1.

4. the control unit operates the valve opening pressure adjusting unit at a timing when the in-cylinder pressure is lower than the pressure of the cleaning gas so that the valve opening pressure of the fuel injection valve in the deactivated state becomes a pressure within a range higher than the in-cylinder pressure and lower than the pressure of the cleaning gas.

2. The fuel injection system according to claim 1.

5. the control unit determines whether or not the in-cylinder pressure is lower than the pressure of the cleaning gas for each cycle period during which a piston reciprocates in a cylinder of the multi-fuel engine.

5. A fuel injection device according to claim 1.

6. The valve opening pressure adjusting unit is a biasing spring that biases the needle valve in a direction that closes the nozzle opening; an acting portion that acts on the biasing spring by utilizing the pressure of the working fluid; Equipped with the valve opening pressure of the needle valve is set to a pressure greater than the pressure of the cleaning gas by the biasing force of the biasing spring; the action portion applies a force to the biasing spring in a direction opposing the biasing force by the pressure of the working fluid, thereby reducing the valve opening pressure of the needle valve to less than the pressure of the cleaning gas.

2. The fuel injection system according to claim 1.

7. The valve opening pressure adjusting unit is a biasing spring that biases the needle valve in a direction that closes the nozzle opening; an action portion that strengthens the biasing force of the biasing spring by utilizing the pressure of the working fluid; Equipped with the valve opening pressure of the needle valve is set by the biasing force of the biasing spring strengthened by the action portion, the action portion reduces the valve opening pressure of the needle valve to less than the pressure of the cleaning gas by releasing the strengthening of the biasing force of the biasing spring.

2. The fuel injection system according to claim 1.

8. a crank angle detector for detecting a crank angle of the multi-fuel engine; The control unit derives the in-cylinder pressure based on the detected crank angle.

5. A fuel injection device according to claim 1.

9. an exhaust valve operation detection unit that detects an exhaust valve operation of the multi-fuel engine; The control unit derives the in-cylinder pressure based on the detected exhaust valve operation.

5. A fuel injection device according to claim 1.

10. further comprising an in-cylinder pressure detection unit that detects the in-cylinder pressure, the control unit determines whether the detected in-cylinder pressure is less than the pressure of the cleaning gas.

5. A fuel injection device according to claim 1.

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