Control device for internal combustion engine

Abstract

To provide a control device for an internal combustion engine capable of suppressing fuel clogging in the internal combustion engine that enables a mixed combustion operation.SOLUTION: A control device is for an internal combustion engine enabling a mixed combustion operation in which both liquid fuel and gaseous fuel are set as use fuel. The internal combustion engine includes: a cylinder having a combustion chamber for burning the use fuel; an injector for injecting the liquid fuel to the combustion chamber; a liquid fuel introduction line for introducing the liquid fuel to the injector; and a gaseous fuel introduction line for introducing the gaseous fuel to the combustion chamber. The control device for the internal combustion engine includes a recovery action execution section configured to take a recovery action for recovering an actual injection amount of the liquid fuel to be injected from the injector when an output reduction amount of the internal combustion engine or a deviation of the actual injection amount of the liquid fuel in the injector from an instructed injection amount exceeds a predetermined threshold value while the internal combustion engine is being operated through the mixed combustion operation.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a control device for an internal combustion engine.

Background Art

[0002] It is known that there is an internal combustion engine capable of a premixed combustion operation using both gaseous fuel and liquid fuel as fuels to be used (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an internal combustion engine capable of a premixed combustion operation, when using a gaseous fuel with relatively low flammability, a liquid fuel is required as an ignition source. In recent years, in order to reduce the environmental load, a decarbonized fuel such as ammonia gas or methanol gas may be used as the gaseous fuel. When using a decarbonized fuel as the gaseous fuel, it may be done to increase the proportion of the decarbonized fuel (gaseous fuel) in the fuel to be used as much as possible. However, fuel clogging may occur in the injector that injects the liquid fuel, leading to a decrease in the output of the internal combustion engine.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a control device for an internal combustion engine that can suppress fuel clogging in an internal combustion engine capable of a premixed combustion operation.

Means for Solving the Problems

[0006] A control device for an internal combustion engine according to at least one embodiment of the present disclosure is a control device for an internal combustion engine capable of a premixed combustion operation using both liquid fuel and gaseous fuel as fuels to be used, The internal combustion engine includes a cylinder having a combustion chamber for burning a fuel to be used, an injector for injecting a liquid fuel into the combustion chamber, a liquid fuel introduction line for guiding the liquid fuel to the injector, and a gaseous fuel introduction line for guiding a gaseous fuel into the combustion chamber. The control device of the internal combustion engine includes a recovery measure execution unit configured to perform a recovery measure for recovering the actual injection amount of the liquid fuel injected from the injector when, in a state where the internal combustion engine is operating by the dual-fuel operation, the output decrease amount of the internal combustion engine or the deviation of the actual injection amount of the liquid fuel in the injector from an instructed injection amount exceeds a predetermined threshold value.

Advantages of the Invention

[0007] According to at least one embodiment of the present disclosure, there is provided a control device for an internal combustion engine that can suppress fuel clogging in an internal combustion engine capable of dual-fuel operation.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0009] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, but are merely illustrative examples.

[0010] (Internal Combustion Engine System) Each of FIGS. 1 and 2 is a schematic diagram of an internal combustion engine system 1 including a control device 3 for an internal combustion engine 2 according to an embodiment of the present disclosure. As shown in FIGS. 1 and 2, the internal combustion engine system 1 includes an internal combustion engine (engine) 2 configured to generate power by burning a fuel used therein, and a control device 3 configured to perform operation control and combustion control of the internal combustion engine 2. In the following embodiments, the case where the internal combustion engine 2 is a four-stroke engine will be described, but some embodiments of the present disclosure are also applicable to the case where the internal combustion engine 2 is a two-stroke engine.

[0011] (Internal Combustion Engine) As shown in FIGS. 1 and 2, the internal combustion engine 2 includes at least one (a plurality in the illustrated example) cylinder 4. Each of the plurality of cylinders 4 has a combustion chamber 40 for burning the fuel used. Although not shown, the combustion chamber 40 is formed between a cylinder body and a piston housed inside the cylinder body. The internal combustion engine 2 is configured to burn the fuel used and a combustion gas (e.g., air) in the combustion chamber 40 of each of the plurality of cylinders 4.

[0012] The internal combustion engine 2 is configured to be capable of a dedicated combustion operation using a liquid fuel as the fuel used, and a mixed combustion operation using both the liquid fuel and a gaseous fuel as the fuel used.

[0013] In some embodiments, the above-described liquid fuel is gas oil, and the above-described gaseous fuel has a lower methane number than gas oil. In one embodiment, the internal combustion engine 2 is a diesel engine. For the purpose of suppressing the emission of greenhouse gases such as carbon dioxide from the internal combustion engine 2, the proportion of gaseous fuel in the fuel used is increased and the proportion of liquid fuel is decreased. As a result, the flow rate of the liquid fuel injected from the injector 50 becomes small, and there is a risk of fuel clogging in the injector 50. Further, when the gaseous fuel has a lower methane number than the liquid fuel, it is necessary to relatively lower the air excess ratio to increase the temperature in the cylinder in order to burn the gaseous fuel. When the temperature in the cylinder is increased, the heat received by the injector 50 becomes excessive, and there is a risk of fuel clogging in the injector 50. Since there is a high possibility of causing fuel clogging in the injector 50 in this way, it is necessary to take recovery measures to quickly eliminate the fuel clogging in the injector 50.

[0014] In still other embodiments, the above-described liquid fuel may be a fuel oil other than gas oil, for example, a renewable fuel oil such as bioethanol.

[0015] In some embodiments, the above-described gaseous fuel is ammonia gas. Since ammonia gas is a gaseous fuel with relatively low flammability, it is necessary to use the liquid fuel as an ignition source. Also, it is necessary to relatively lower the air excess ratio to increase the temperature in the cylinder in order to burn the gaseous fuel with relatively low flammability. In still other embodiments, the above-described gaseous fuel may be a gaseous fuel other than ammonia gas, for example, hydrogen gas and methanol gas.

[0016] As shown in FIGS. 1 and 2, the internal combustion engine 2 includes a plurality of injectors 50 for injecting liquid fuel into the combustion chambers 40 of the respective cylinders 4, a liquid fuel introduction line 5 for guiding the liquid fuel to the injectors 50, and a gaseous fuel introduction line 6 for guiding gaseous fuel to each of the plurality of combustion chambers 40. The injectors 50 are provided individually for each cylinder 4. Each of the plurality of injectors 50 includes a fuel injection valve configured to inject liquid fuel into the corresponding combustion chamber 40.

[0017] In the illustrated embodiment, as shown in FIGS. 1 and 2, the internal combustion engine 2 further includes a combustion gas introduction line 7 for guiding combustion gas to each of the plurality of combustion chambers 40, and an exhaust gas discharge line 8 for discharging exhaust gas from each of the plurality of combustion chambers 40.

[0018] (Liquid fuel introduction line) The liquid fuel introduction line 5 forms a flow path for supplying liquid fuel to each of the plurality of injectors 50 and is not limited to piping. In the illustrated embodiment, as shown in FIGS. 1 and 2, the liquid fuel introduction line 5 includes a common rail 51 capable of storing liquid fuel, a plurality of branch pipes 52 for introducing liquid fuel from the common rail 51 to each of the plurality of injectors 50, a liquid fuel pipe 54 for guiding liquid fuel from a supply source of the liquid fuel (for example, a storage tank for storing the liquid fuel) 53 to the common rail 51, and a pressure boosting device (for example, a pressure boosting pump) 55 for boosting the liquid fuel guided to the common rail 51.

[0019] One end of each of the plurality of branch pipes 52 is connected to the common rail 51, and the other end is connected to the injector 50 corresponding to the branch pipe 52. One end of the liquid fuel pipe 54 is connected to the common rail 51, and the other end is connected to the supply source 53 of the liquid fuel. The pressure boosting device 55 is provided in the liquid fuel pipe 54.

[0020] As shown in FIG. 1, the internal combustion engine 2 may include a pressure acquisition device (pressure sensor in the illustrated example) 56 configured to acquire the pressure of the liquid fuel guided to the common rail 51. In the illustrated embodiment, the pressure acquisition device 56 is disposed on the downstream side (common rail 51 side) of the pressure booster 55 in the liquid fuel pipe 54, and is configured to acquire the pressure of the liquid fuel flowing on the downstream side of the pressure booster 55 in the liquid fuel pipe 54.

[0021] As shown in FIG. 2, the internal combustion engine 2 may include a flow rate acquisition device (flow rate sensor in the illustrated example) 57 configured to acquire the flow rate of the liquid fuel guided to the common rail 51. In the illustrated embodiment, the flow rate acquisition device 57 is disposed on the upstream side (supply source 53 side) of the pressure booster 55 in the liquid fuel pipe 54, and is configured to acquire the flow rate of the liquid fuel flowing on the upstream side of the pressure booster 55 in the liquid fuel pipe 54. Note that the flow rate acquisition device 57 may be disposed on the downstream side (common rail 51 side) of the pressure booster 55 in the liquid fuel pipe 54, and may be configured to acquire the flow rate of the liquid fuel flowing on the downstream side of the pressure booster 55 in the liquid fuel pipe 54.

[0022] (Gas fuel introduction line) The gas fuel introduction line 6 forms a flow path for supplying gas fuel to each of the plurality of combustion chambers 40, and is not limited to piping. In the illustrated embodiment, the gas fuel introduction line 6 includes a gas fuel pipe 61 for guiding gas fuel from a gas fuel supply source (for example, a storage tank storing gas fuel) 63, and a plurality of branch pipes 62 for introducing gas fuel from the gas fuel pipe 61 into each of the plurality of combustion chambers 40. One end of each of the plurality of branch pipes 62 is connected to the gas fuel pipe 61, and the other end is connected to the combustion chamber 40 corresponding to the branch pipe 62. The gas fuel supply source 63 may store the gas fuel in a gaseous state or in a liquid state.

[0023] (Combustion gas introduction line) The combustion gas introduction line 7 forms a flow path for supplying combustion gas to each of the plurality of combustion chambers 40 and is not limited to piping. In the illustrated embodiment, the combustion gas introduction line 7 includes a combustion gas pipe 71 for guiding combustion gas from a supply source of the combustion gas, and a plurality of branch pipes 72 for introducing the combustion gas from the combustion gas pipe 71 into each of the plurality of combustion chambers 40. One end of each of the plurality of branch pipes 72 is connected to the combustion gas pipe 71, and the other end is connected to the corresponding combustion chamber 40 to which the branch pipe 72 corresponds. One end (upstream end) of the combustion gas pipe 71 may be open to the atmosphere or may be connected to a storage tank for storing the combustion gas.

[0024] In the embodiments shown in FIGS. 1 and 2, the combustion gas introduction line 7 merges into the gas fuel introduction line 6 at a confluence P1 provided in the gas fuel pipe 61 and shares the downstream side (combustion chamber 40 side) from the confluence P1 with the gas fuel introduction line 6. That is, on the downstream side from the confluence P1, the gas fuel pipe 61 also serves as the combustion gas pipe 71, and each of the plurality of branch pipes 62 also serves as the corresponding branch pipe 72. The gas fuel is introduced into the combustion chamber 40 in a mixed gas state mixed with the combustion gas and burns in the mixed gas state. In order to burn the gas fuel, it is necessary to relatively lower the air excess ratio and raise the temperature in the cylinder 4. When the temperature in the cylinder 4 rises, the heat received by the injector 50 becomes excessive, which may cause fuel clogging in the injector 50. For this reason, it is necessary to take recovery measures to quickly eliminate fuel clogging in the injector 50.

[0025] In the embodiments shown in FIGS. 1 and 2, the gas fuel pipe 61 includes an upstream gas fuel pipe 64 having one end connected to a supply source 63 of the gas fuel and the other end connected to the combustion gas pipe 71 at the confluence P1.

[0026] As shown in FIGS. 1 and 2, the internal combustion engine 2 may further include a flow rate adjustment device (a flow rate adjustment valve in the illustrated example) 65 configured to adjust the flow rate of gaseous fuel guided to each of the plurality of combustion chambers 40. The flow rate adjustment device 65 may be provided in the gaseous fuel pipe 61 (the upstream gaseous fuel pipe 64 in the illustrated example), or may be provided in each of the plurality of branch pipes 62.

[0027] As shown in FIGS. 1 and 2, the internal combustion engine 2 may further include a mixer (a static mixer in the illustrated example) 66 configured to continuously mix gaseous fuel and combustion gas. In the illustrated embodiment, the mixer 66 is provided downstream of the confluence P1 of the gaseous fuel pipe 61.

[0028] (Exhaust gas discharge line) The exhaust gas discharge line 8 forms a flow path for discharging exhaust gas from each of the plurality of combustion chambers 40 and is not limited to piping. In the illustrated embodiment, the exhaust gas discharge line 8 includes an exhaust gas pipe 81 and a plurality of branch pipes 82 for discharging exhaust gas from each of the plurality of combustion chambers 40 to the exhaust gas pipe 81. One end of each of the plurality of branch pipes 82 is connected to the exhaust gas pipe 81, and the other end is connected to the combustion chamber 40 corresponding to the branch pipe 82. One end (the downstream end) of the exhaust gas pipe 81 may be connected to a chimney (not shown).

[0029] As shown in FIGS. 1 and 2, the internal combustion engine 2 may further include an oxidation catalyst (DOC) 83 provided in the exhaust gas pipe 81 for oxidizing hydrocarbons and carbon monoxide contained in the exhaust gas flowing through the exhaust gas pipe 81. Further, as shown in FIGS. 1 and 2, an orifice 84 for generating back pressure may be provided in the exhaust gas pipe 81.

[0030] As shown in FIGS. 1 and 2, the internal combustion engine 2 may further include an analyzer 85 provided in the exhaust gas pipe 81 for obtaining the concentration of nitrogen oxides contained in the exhaust gas flowing through the exhaust gas pipe 81, and an analyzer 86 provided in the exhaust gas pipe 81 for obtaining the concentration of ammonia gas and dinitrogen monoxide contained in the exhaust gas flowing through the exhaust gas pipe 81.

[0031] (Control Device for Internal Combustion Engine) The control device 3 for the internal combustion engine 2 is an electronic control unit that controls the operation of each device provided in the internal combustion engine 2, such as the injector 50, the booster 55, and the flow rate adjustment device 65. The control device 3 may be configured as a microcomputer including a central processing unit (CPU) including a processor, a random access memory (RAM), a read only memory (ROM), and an I / O interface. In the illustrated embodiment, the control device 3 consists of an engine control unit. Note that, in some other embodiments, the control device 3 may be implemented as one of the functions (programs and circuits) provided in the engine control unit. Also, in some other embodiments, the control device 3 may be configured as an electronic control unit different from the engine control unit.

[0032] The control device 3 for the internal combustion engine 2 includes a control unit 30 configured to perform operation control and combustion control of the internal combustion engine 2 according to the operation mode of the internal combustion engine 2. The internal combustion engine 2 may include a switching device (switch) 10 for manually switching the operation mode of the internal combustion engine 2. The control unit 30 is configured to perform operation control and combustion control of the internal combustion engine 2 according to the information (signal) regarding the operation mode sent from the switching device 10. When the operation mode of the internal combustion engine 2 is the dedicated combustion operation, the control unit 30 is configured to close the flow rate adjustment device 65 and perform opening and closing control of the injector 50 to burn the liquid fuel and the combustion gas in the combustion chamber 40. Also, when the operation mode of the internal combustion engine 2 is the mixed combustion operation, the control unit 30 is configured to open the flow rate adjustment device 65 and perform opening and closing control of the injector 50 to burn the liquid fuel, the mixture of the gaseous fuel and the combustion gas, in the combustion chamber 40.

[0033] When the operation mode of the internal combustion engine 2 is the dedicated combustion operation, the control unit 30 is configured to perform combustion control of the internal combustion engine 2 so that the ratio of the gaseous fuel in the fuel used becomes as large as possible in order to suppress the generation of greenhouse gases.

[0034] As shown in FIGS. 1 and 2, the control device 3 for the internal combustion engine 2 according to some embodiments includes a recovery measure execution unit 31. The recovery measure execution unit 31 is configured to monitor the output of the internal combustion engine 2 and calculate the amount of decrease with respect to the steady output, which is the output of the internal combustion engine 2 when the internal combustion engine 2 is operated in a steady state by a dual-fuel operation. The recovery measure execution unit 31 is configured to perform a recovery measure for recovering the actual injection amount of the liquid fuel injected from the injector 50 when the amount of output decrease of the internal combustion engine 2 exceeds a predetermined threshold value in a state where the internal combustion engine 2 is operated by a dual-fuel operation.

[0035] FIG. 3 is a control flowchart of the internal combustion engine 2 according to an embodiment of the present disclosure. The control flow shown in FIG. 3 is performed by the recovery measure execution unit 31. When starting the internal combustion engine 2 (step S1) and the internal combustion engine 2 is operating in the above-described dedicated-fuel operation state (”No” in step S2), the determination of the output decrease amount (step S4) described later is not performed, and the dedicated-fuel operation of the internal combustion engine 2 is continued (step S3).

[0036] When the internal combustion engine 2 is operating in the above-described dual-fuel operation state (”Yes” in step S2), the determination of the output decrease amount (step S4) is performed. When the output decrease amount is less than a predetermined threshold value (”No” in step S4), the dual-fuel operation of the internal combustion engine 2 is continued (step S5) assuming that the injector 50 is not clogged. When the output decrease amount exceeds a predetermined threshold value (”Yes” in step S4), the above-described recovery measure is performed (step S6) assuming that the injector 50 is clogged.

[0037] When the output reduction amount of the internal combustion engine 2 exceeds a predetermined threshold value, there is a high probability that fuel clogging has occurred in the injector 50. In this case, the recovery measure execution unit 31 takes a recovery measure to restore the actual injection amount of the liquid fuel injected from the injector 50, thereby enabling early elimination of the fuel clogging in the injector 50. As a recovery measure (step S6), there is an example of giving a notification that prompts switching the operation mode of the internal combustion engine 2 to a dedicated combustion operation using liquid fuel, as shown in FIG. 3.

[0038] In the embodiment shown in FIG. 3, when the output reduction amount of the internal combustion engine 2 exceeds a predetermined threshold value (``Yes'' in step S4), a notification is given to prompt switching the operation mode of the internal combustion engine 2 to a dedicated combustion operation using liquid fuel (step S7). The recovery measure execution unit 31 includes a notification instruction unit 311 (see FIGS. 1 and 2). The notification instruction unit 311 is configured to cause the notification device 9 to give a notification that prompts switching the operation mode of the internal combustion engine 2 to a dedicated combustion operation using liquid fuel when the output reduction amount of the internal combustion engine 2 exceeds a predetermined threshold value (``Yes'' in step S4). The notification device 9 receives the above notification instruction from the notification instruction unit 311 and gives the above notification. The notification device 9 may be a display device (display) that outputs the above notification as an image, or may be an acoustic device (speaker) that outputs the above notification as sound.

[0039] The notification device 9 according to the instruction from the notification instruction unit 311 can give a notification to prompt the user of the internal combustion engine 2 to switch to the dedicated combustion operation. The user of the internal combustion engine 2 who has received the notification can switch the operation mode of the internal combustion engine 2 to the dedicated combustion operation by operating the switching device 10 at a desired time. By switching the operation mode of the internal combustion engine 2 to the dedicated combustion operation, the injection amount of the liquid fuel in the injector 50 can be increased. By increasing the injection amount of the liquid fuel in the injector 50, the fuel clogging in the injector 50 can be directly eliminated.

[0040] In the embodiment shown in FIG. 3, when an operation to switch to dedicated combustion operation is performed after the above notification (Yes in step S8), in order to confirm whether the clogging of the injector 50 has been eliminated by the dedicated combustion operation, the determination of the output reduction amount (step S4) is performed again.

[0041] In the embodiment shown in FIG. 3, when an operation to switch to dedicated combustion operation is not performed after the above notification, the above notification by the notification device 9 is performed again. The above notification by the notification device 9 may be performed at regular intervals. As shown in FIG. 3, in a state where the operation mode of the internal combustion engine 2 is maintained in the mixed combustion operation without performing the operation to switch to the dedicated combustion operation (No in step S8), when the above notification (notification count N) by the notification device 9 is performed a predetermined number of times N1 or more (Yes in step S9), the output of the internal combustion engine 2 may be forcibly limited in order to prompt the above operation. The predetermined number of times N1 is preferably a plurality of times of 2 or more. The recovery measure execution unit 31 includes a notification instruction unit 311 and an output limitation unit 312 (see FIGS. 1 and 2). The output limitation unit 312 is configured to limit the output of the internal combustion engine 2 to a predetermined output or less (for example, 50% or less of the steady output) when the notification (notification count N) by the notification device 9 is performed a predetermined number of times N1 or more (Yes in step S9 of FIG. 3) (step S10). By limiting the output of the internal combustion engine 2 to a predetermined output or less by the output limitation unit 312, it is possible to strongly prompt the user of the internal combustion engine 2 to switch to the dedicated combustion operation.

[0042] In some embodiments, the above-described recovery measure execution unit 31 is configured to acquire the actual injection amount of the liquid fuel in the injector 50 and calculate the deviation of the actual injection amount of the liquid fuel in the injector 50 from the instructed injection amount. The recovery measure execution unit 31 is configured to perform a recovery measure for recovering the actual injection amount of the liquid fuel injected from the injector 50 when the above deviation exceeds a predetermined threshold value in a state where the internal combustion engine 2 is operating by mixed combustion operation.

[0043] In the embodiment shown in FIG. 1, the recovery measure execution unit 31 is configured to monitor the pressure of the liquid fuel acquired by the pressure acquisition device 56. Based on the association information that associates the change amount (decrease amount) of the pressure of the liquid fuel acquired by the pressure acquisition device 56 with the actual injection amount of the liquid fuel in the injector 50, the recovery measure execution unit 31 acquires the actual injection amount of the liquid fuel in the injector 50 from the change amount of the pressure of the liquid fuel acquired by the pressure acquisition device 56.

[0044] In the embodiment shown in FIG. 2, the recovery measure execution unit 31 is configured to monitor the flow rate of the liquid fuel acquired by the flow rate acquisition device 57. Based on the association information that associates the change amount (increase amount) of the flow rate of the liquid fuel acquired by the flow rate acquisition device 57 with the actual injection amount of the liquid fuel in the injector 50, the recovery measure execution unit 31 acquires the actual injection amount of the liquid fuel in the injector 50 from the change amount of the flow rate of the liquid fuel acquired by the flow rate acquisition device 57.

[0045] FIG. 4 is a control flowchart of the internal combustion engine 2 according to an embodiment of the present disclosure. The control flow shown in FIG. 4 is performed by the recovery measure execution unit 31. When starting the internal combustion engine 2 (step S1) and the internal combustion engine 2 is operating in the dedicated combustion operation described above (''No'' in step S2), the determination of the deviation amount (step S4) described later is not performed, and the dedicated combustion operation of the internal combustion engine 2 is continued (step S3). When the internal combustion engine 2 is operating in the above-described mixed combustion operation (''Yes'' in step S2), the determination of the deviation amount of the actual injection amount of the liquid fuel from the indicated injection amount (step S4) is performed. When the deviation amount is less than the predetermined threshold (''No'' in step S4), the mixed combustion operation of the internal combustion engine 2 is continued (step S5) assuming that the injector 50 is not clogged. When the deviation amount exceeds the predetermined threshold (''Yes'' in step S4), the above recovery measure is performed (step S6) assuming that the injector 50 is clogged.

[0046] Fuel clogging in the injector 50 causes a deviation of the actual injection amount of the liquid fuel in the injector 50 from the indicated injection amount. This deviation is directly related to the fuel clogging in the injector 50 as compared to the output reduction of the internal combustion engine 2 caused by various factors. When the deviation amount exceeds a predetermined threshold value, there is a high probability that fuel clogging has occurred in the injector 50. In this case, the recovery measure execution unit 31 performs a recovery measure to recover the actual injection amount of the liquid fuel injected from the injector 50, thereby enabling early elimination of the fuel clogging in the injector 50. As the recovery measure (step S6), as shown in FIG. 4, increasing the proportion of the liquid fuel in the fuel used can be mentioned.

[0047] In the embodiment shown in FIG. 4, when the deviation amount of the actual injection amount of the liquid fuel from the indicated injection amount exceeds a predetermined threshold value (''Yes'' in step S4), the proportion of the liquid fuel in the fuel used is increased (step S11). The recovery measure execution unit 31 is configured to increase the proportion of the liquid fuel in the fuel used when the above-described deviation amount exceeds a predetermined threshold value (''Yes'' in step S4). In one embodiment, the above-described recovery measure execution unit 31 is configured to set the proportion of the liquid fuel in the fuel used to 80% or more as the above-described recovery measure. By increasing the proportion of the liquid fuel in the fuel used, the injection amount of the liquid fuel in the injector 50 can be increased. By increasing the injection amount of the liquid fuel in the injector 50, the fuel clogging in the injector 50 can be directly eliminated.

[0048] In step S11 described above, for the purpose of increasing the proportion of the liquid fuel in the fuel used, the operation mode of the internal combustion engine 2 may be switched to a dedicated combustion operation using the liquid fuel as the fuel used. In some embodiments, the above-described recovery measure execution unit 31 is configured to switch the operation mode of the internal combustion engine 2 to a dedicated combustion operation using the liquid fuel as the fuel used for the purpose of increasing the proportion of the liquid fuel in the fuel used.

[0049] By switching the operation mode of the internal combustion engine 2 to the dedicated combustion operation, the injection amount of the liquid fuel in the injector 50 can be increased. By increasing the injection amount of the liquid fuel in the injector 50, fuel clogging in the injector 50 can be directly eliminated.

[0050] The determination as to whether or not the deviation amount exceeds a predetermined threshold value may be made for each cylinder 4, and the above recovery measure may be performed for the cylinder 4 in which the deviation amount exceeds the predetermined threshold value. That is, the above recovery measure may not be performed for the cylinder 4 in which the deviation is less than the predetermined threshold value.

[0051] FIG. 5 is a control flowchart of the internal combustion engine 2 according to an embodiment of the present disclosure. The control flow shown in FIG. 5 is performed by the recovery measure execution unit 31. In the embodiment shown in FIG. 5, when the deviation amount of the actual injection amount of the liquid fuel from the instructed injection amount exceeds a predetermined threshold value (''Yes'' in step S4), an injection amount recovery operation is performed as the above-described recovery measure (step S12). The recovery measure execution unit 31 is configured to execute an injection amount recovery operation when the above-described deviation amount exceeds a predetermined threshold value (''Yes'' in step S4).

[0052] FIGS. 6 and 7 are explanatory diagrams for explaining the recovery measure of the injector 50 in an embodiment of the present disclosure. In FIGS. 6 and 7, a graph is shown with the time T on the horizontal axis and the injection pressure IP of the injector 50 on the vertical axis. L1 shown in FIGS. 6 and 7 indicates the change in the injection pressure IP when the operation mode of the internal combustion engine 2 is the dedicated combustion operation. L2 and L3 shown in FIGS. 6 and 7 indicate the change in the injection pressure IP in the injection amount recovery operation.

[0053] In some embodiments, the above-described recovery measure execution unit 31 is configured to increase the injection pressure IP, which is the pressure of the liquid fuel injected from the injector 50, more than that during the dedicated combustion operation as the above-described recovery measure (injection amount recovery operation). As shown in FIG. 6, the maximum value IP2 of the injection pressure during the injection amount recovery operation is larger than the maximum value IP1 of the injection pressure during the dedicated combustion operation. By increasing the injection pressure, which is the pressure of the liquid fuel injected from the injector 50 during the injection amount recovery operation, more than that during the dedicated combustion operation, fuel clogging in the injector 50 can be directly eliminated.

[0054] In some embodiments, the above-described recovery measure execution unit 31 is configured to pulsate the injection pressure, which is the pressure of the liquid fuel injected from the injector 50, with a predetermined pulsation limit width LW as the above-described recovery measure (injection amount recovery operation). As shown in FIG. 7, in the injection amount recovery operation, within the range of the predetermined pulsation limit width LW, the injection pressure IP is gradually decreased (L3A in FIG. 7) or the injection pressure IP is gradually increased (L3B in FIG. 7). Note that, in the injection amount recovery operation, there may be a period during which the injection pressure IP is kept constant (L3C in FIG. 7). The maximum value IP3 of the injection pressure during the injection amount recovery operation may be the same as the maximum value IP1 of the injection pressure during the dedicated combustion operation, or may be larger than the maximum value IP1. By pulsating the injection pressure, which is the pressure of the liquid fuel injected from the injector 50 during the injection amount recovery operation, with a predetermined pulsation limit width LW, fuel clogging in the injector 50 can be directly eliminated.

[0055] In some of the above-described embodiments, the control flows shown in FIGS. 3 to 5 were performed by the recovery measure execution unit 31 of the control device 3, but a part of these control flows may be performed manually or by a part other than the recovery measure execution unit 31 of the control device 3 or by a device other than the control device 3.

[0056] In this specification, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent states where there are tolerances, or relative displacements with angles and distances such that the same function can be obtained. For example, expressions indicating that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent states where there are tolerances, or differences such that the same function can be obtained. Also, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent shapes such as a rectangular shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. Also, in this specification, the expressions "comprising", "including", or "having" for one component are not exclusive expressions excluding the existence of other components.

[0057] The present disclosure is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms. For example, when the output reduction amount of the internal combustion engine 2 exceeds a predetermined threshold value, the recovery measures shown in FIGS. 4 and 5 may be implemented. Also, when the above-described deviation amount exceeds a predetermined threshold value, the recovery measures shown in FIG. 3 may be implemented.

[0058] The content described in some of the above-described embodiments is understood as follows, for example.

[0059] 1) The control device (3) of the internal combustion engine (2) according to at least one embodiment of the present disclosure is a control device (3) of an internal combustion engine (2) capable of performing a mixed combustion operation using both liquid fuel and gaseous fuel, wherein the internal combustion engine (2) has a cylinder (4) having a combustion chamber (40) for burning the fuel to be used, an injector (50) for injecting liquid fuel into the combustion chamber (40), A liquid fuel introduction line (5) for guiding the liquid fuel to the injector (50); A gaseous fuel introduction line (6) for guiding gaseous fuel to the combustion chamber (40); and A control device (3) of the internal combustion engine (2) includes a recovery measure execution unit (31) configured to perform a recovery measure for recovering the actual injection amount of the liquid fuel injected from the injector (50) when a decrease in the output of the internal combustion engine (2) or a deviation of the actual injection amount of the liquid fuel in the injector (50) from an instructed injection amount exceeds a predetermined threshold value in a state where the internal combustion engine (2) is operating by the dual-fuel operation.

[0060] According to the configuration of 1) above, when the decrease in the output of the internal combustion engine (2) or the deviation of the actual injection amount of the liquid fuel in the injector (50) from the instructed injection amount exceeds a predetermined threshold value, there is a high probability that fuel clogging has occurred in the injector (50). In this case, by performing a recovery measure for recovering the actual injection amount of the liquid fuel injected from the injector (50) by the recovery measure execution unit (31), early elimination of fuel clogging in the injector (50) can be achieved. Thereby, fuel clogging in the injector (50) can be suppressed, and a decrease in the output of the internal combustion engine (2) due to fuel clogging can be suppressed.

[0061] 2) In some embodiments, there is provided a control device (3) of the internal combustion engine (2) according to 1) above, wherein the recovery measure execution unit (31) is configured to perform the recovery measure when a decrease in the output of the internal combustion engine (2) exceeds the predetermined threshold value in a state where the internal combustion engine (2) is operating by the dual-fuel operation.

[0062] According to the configuration of 2) above, fuel clogging in the injector (50) causes a decrease in the output of the internal combustion engine (2). When the amount of output decrease of the internal combustion engine (2) exceeds a predetermined threshold value, since the probability of fuel clogging occurring in the injector (50) is high, by performing the above recovery measure, the fuel clogging in the injector (50) can be eliminated at an early stage.

[0063] 3) In some embodiments, it is the control device (3) of the internal combustion engine (2) described in 1) above, The recovery measure execution unit (31) is configured to perform the recovery measure when the deviation of the actual injection amount of the liquid fuel in the injector (50) from the instructed injection amount exceeds the predetermined threshold value in a state where the internal combustion engine (2) is operating by the mixed combustion operation.

[0064] According to the configuration of 3) above, fuel clogging in the injector (50) causes a deviation of the actual injection amount of the liquid fuel in the injector (50) from the instructed injection amount. This deviation is directly related to the fuel clogging in the injector (50) as compared to the decrease in the output of the internal combustion engine (2) caused by various factors. When the deviation exceeds a predetermined threshold value, since the probability of fuel clogging occurring in the injector (50) is high, by performing the above recovery measure, the fuel clogging in the injector (50) can be eliminated at an early stage.

[0065] 4) In some embodiments, it is the control device (3) of the internal combustion engine (2) described in any one of 1) to 3) above, The recovery measure execution unit (31) increases the ratio of the liquid fuel in the fuel used as the recovery measure.

[0066] According to the configuration of 4) above, by increasing the ratio of the liquid fuel in the fuel used, the injection amount of the liquid fuel in the injector (50) can be increased. By increasing the injection amount of the liquid fuel in the injector (50), the fuel clogging in the injector (50) can be directly eliminated.

[0067] 5) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) described in 4) above, wherein the recovery measure execution unit (31) switches the operation mode of the internal combustion engine to a dedicated combustion operation using the liquid fuel as the fuel to be used.

[0068] According to the configuration of 5) above, by switching the operation mode of the internal combustion engine (2) to dedicated combustion operation, the injection amount of the liquid fuel in the injector (50) can be increased. By increasing the injection amount of the liquid fuel in the injector (50), fuel clogging in the injector (50) can be directly eliminated.

[0069] 6) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) described in any one of 1) to 5) above, wherein the recovery measure execution unit (31) increases the injection pressure, which is the pressure of the liquid fuel injected from the injector, as the recovery measure, to be higher than that during dedicated combustion operation.

[0070] According to the configuration of 6) above, by increasing the injection pressure, which is the pressure of the liquid fuel injected from the injector (50), to be higher than that during dedicated combustion operation, fuel clogging in the injector (50) can be directly eliminated.

[0071] 7) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) described in any one of 1) to 6) above, wherein the recovery measure execution unit (31) pulsates the injection pressure, which is the pressure of the liquid fuel injected from the injector, as the recovery measure, with a predetermined pulsation limit width.

[0072] According to the configuration of 7) above, by pulsating the injection pressure, which is the pressure of the liquid fuel injected from the injector (50), with a predetermined pulsation limit width, fuel clogging in the injector (50) can be directly eliminated.

[0073] 8) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) according to any one of 1) to 7) above, when the output reduction amount of the internal combustion engine (2) or the deviation of the actual injection amount of the liquid fuel in the injector (50) from the instructed injection amount exceeds the predetermined threshold value while the internal combustion engine (2) is operating in the co-firing operation, the recovery measure execution unit (31) includes a notification instruction unit (311) configured to cause the notification device (9) to issue a notification prompting the switching of the operation mode of the internal combustion engine (2) to a dedicated firing operation using the liquid fuel as the fuel to be used.

[0074] According to the configuration of 8) above, the notification device (9) can notify the user of the internal combustion engine (2) to prompt switching to the dedicated firing operation. As a result, the user of the internal combustion engine (2) can switch the operation mode of the internal combustion engine (2) to the dedicated firing operation at a desired time. By switching the operation mode of the internal combustion engine (2) to the dedicated firing operation, the injection amount of the liquid fuel in the injector (50) can be increased. By increasing the injection amount of the liquid fuel in the injector (50), fuel clogging in the injector (50) can be directly eliminated.

[0075] 9) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) according to 8) above, the recovery measure execution unit (31) further includes an output limitation unit (312) configured to limit the output of the internal combustion engine (2) to a predetermined output or less when the notification by the notification device (9) has been performed a predetermined number of times or more.

[0076] According to the configuration of 9) above, by limiting the output of the internal combustion engine (2) to a predetermined output or less by the output limitation unit (312), the user of the internal combustion engine (2) can be strongly prompted to switch to the dedicated firing operation.

[0077] 10) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) according to any one of 1) to 9) above, the internal combustion engine (2) A combustion gas introduction line (7) for introducing combustion gas into the combustion chamber, which merges at a confluence (P1) with the gaseous fuel introduction line (6) and shares the downstream side of the confluence (P1) with the gaseous fuel introduction line (6).

[0078] According to the configuration of 10) above, the gaseous fuel is introduced into the combustion chamber (40) in a mixed gas state mixed with the combustion gas and is combusted in the mixed gas state. In order to combust the gaseous fuel, it is necessary to relatively lower the air excess ratio and increase the temperature in the cylinder (4). When the temperature in the cylinder (4) is increased, the heat received by the injector (50) becomes excessive, which may cause fuel clogging in the injector (50). Therefore, it is necessary to take the above recovery measures to quickly eliminate fuel clogging in the injector (50).

[0079] 11) In some embodiments, it is a control device (3) for an internal combustion engine (2) according to any one of 1) to 10) above, The liquid fuel is light oil, The gaseous fuel has a lower methane number than the light oil.

[0080] According to the configuration of 11) above, for the purpose of suppressing the emission of greenhouse gases such as carbon dioxide from the internal combustion engine (2), the proportion of gaseous fuel in the fuel used is increased and the proportion of liquid fuel is decreased. As a result, the flow rate of the liquid fuel injected from the injector (50) becomes small, which may cause fuel clogging in the injector (50). Also, according to the configuration of 11) above, when the gaseous fuel has a lower methane number than the liquid fuel, it is necessary to relatively lower the air excess ratio to increase the temperature in the cylinder in order to combust the gaseous fuel. When the temperature in the cylinder is increased, the heat received by the injector (50) becomes excessive, which may cause fuel clogging in the injector (50). Since there is a high possibility of causing fuel clogging in the injector (50) in this way, it is necessary to take the above recovery measures to quickly eliminate fuel clogging in the injector (50).

[0081] 12) In some embodiments, there is provided a control device (3) for an internal combustion engine (2) according to any one of 1) to 10) above, wherein the gaseous fuel is ammonia gas.

[0082] According to the configuration of 12) above, since ammonia gas is a gaseous fuel with relatively low combustibility, it is necessary to use a liquid fuel as an ignition source. Also, in order to burn a gaseous fuel with relatively low combustibility, it is necessary to relatively lower the air excess ratio to increase the temperature inside the cylinder.

Explanation of Reference Numerals

[0083] 1 Internal combustion engine system 2 Internal combustion engine 3 Control device 4 Cylinder 5 Liquid fuel introduction line 6 Gaseous fuel introduction line 7 Combustion gas introduction line 8 Exhaust gas discharge line 9 Notification device 10 Switching device 30 Control unit 31 Recovery measure execution unit 40 Combustion chamber 50 Injector 51 Common rail

Claims

1. A control device for an internal combustion engine capable of performing a mixed combustion operation using both liquid fuel and gaseous fuel as the fuel to be used, The internal combustion engine includes: A cylinder having a combustion chamber for burning the fuel to be used, An injector for injecting liquid fuel into the combustion chamber, A liquid fuel introduction line for guiding the liquid fuel to the injector, A gaseous fuel introduction line for guiding gaseous fuel into the combustion chamber, The control device for the internal combustion engine includes: In a state where the internal combustion engine is operating by the mixed combustion operation, when the output reduction amount of the internal combustion engine or the deviation of the actual injection amount of the liquid fuel in the injector from the indicated injection amount exceeds a predetermined threshold value, a recovery measure execution unit configured to perform a recovery measure for recovering the actual injection amount of the liquid fuel injected from the injector. A control device for an internal combustion engine.

2. The recovery measure execution unit is configured to perform the recovery measure when the output reduction amount of the internal combustion engine exceeds the predetermined threshold value in a state where the internal combustion engine is operating by the mixed combustion operation. The control device for an internal combustion engine according to claim 1.

3. The recovery measure execution unit is configured to perform the recovery measure when the deviation of the actual injection amount of the liquid fuel in the injector from the indicated injection amount exceeds the predetermined threshold value in a state where the internal combustion engine is operating by the mixed combustion operation. The control device for an internal combustion engine according to claim 1.

4. The recovery measure execution unit: Increases the ratio of the liquid fuel in the fuel to be used as the recovery measure. The control device for an internal combustion engine according to any one of claims 1 to 3.

5. The recovery measure execution unit: Switch the operation mode of the internal combustion engine to dedicated combustion operation using the liquid fuel as the fuel to be used. The control device for an internal combustion engine according to claim 4.

6. The recovery measure execution unit Increase the injection pressure, which is the pressure of the liquid fuel injected from the injector, as the recovery measure, to be higher than that during dedicated combustion operation. The control device for an internal combustion engine according to any one of claims 1 to 3.

7. The recovery measure execution unit Pulse the injection pressure, which is the pressure of the liquid fuel injected from the injector, as the recovery measure, with a predetermined pulsation limit width. The control device for an internal combustion engine according to any one of claims 1 to 3.

8. The recovery measure execution unit In a state where the internal combustion engine is operating in the mixed combustion operation, when the output reduction amount of the internal combustion engine or the deviation of the actual injection amount of the liquid fuel in the injector from the instructed injection amount exceeds the predetermined threshold value, a notification instruction unit configured to cause a notification device to notify to prompt switching of the operation mode of the internal combustion engine to dedicated combustion operation using the liquid fuel as the fuel to be used is included. The control device for an internal combustion engine according to any one of claims 1 to 3.

9. The recovery measure execution unit Further includes an output limitation unit configured to limit the output of the internal combustion engine to a predetermined output or less when the notification by the notification device has been performed a predetermined number of times or more. The control device for an internal combustion engine according to claim 8.

10. The internal combustion engine Further includes a combustion gas introduction line for introducing combustion gas into the combustion chamber, which merges at a confluence with the gas fuel introduction line and shares the downstream side of the confluence with the gas fuel introduction line. The control device for an internal combustion engine according to any one of claims 1 to 3.

11. The liquid fuel is light oil, and the gaseous fuel has a lower methane number than the light oil. The control device for an internal combustion engine according to any one of claims 1 to 3.

12. The gaseous fuel is ammonia gas, The control device for an internal combustion engine according to any one of claims 1 to 3.

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