Electronic control device for hydrogen co-firing and hydrogen blend ratio control method

Abstract

To provide an electronic control device for mixed hydrogen combustion, which can control an engine supplied with a multi-fuel, in which hydrogen is a part of the fuel, in accordance with an abnormality in the combustion state.SOLUTION: An electronic control device 12 for mixed hydrogen combustion comprises: a combustion timing detection unit 21 that detects the combustion timing of an engine 18; an abnormal state detection unit 24 that detects an abnormal state, in which a type of abnormality occurring in the engine 18 is determined, on the basis of the combustion timing and a second fuel supply ratio calculated from the supply amount of hydrocarbon fuel supplied by a first fuel supply device and the supply amount of a second fuel supplied by a second fuel supply device; and a control mode determination unit 25 that determines a control mode corresponding to the abnormal state, controls the supply amount of hydrogen to be supplied by the second fuel supply device on the basis of the control mode, and outputs the control mode to an engine controller 11 for controlling the engine 18.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electronic control device for hydrogen-mixed combustion and a method for controlling the hydrogen mixing ratio. [Background technology]

[0002] As a decarbonization system to reduce the use of fossil fuels, hydrogen co-firing engine systems that utilize hydrogen produced from renewable energy sources are being considered for power generation, cogeneration, etc. Because hydrogen has a combustion speed approximately seven times faster than conventional hydrocarbon fuels, it is possible to improve thermal efficiency by adjusting the supply of hydrogen.

[0003] On the other hand, the combustion state, such as the combustion timing, changes significantly depending on the amount of hydrogen supplied, and abnormal combustion such as backfire, afterfire, pre-ignition, and knocking may occur. When such abnormal combustion occurs, the engine may break down in some cases. In addition, although hydrogen is a highly combustible fuel, it has a flammable range like other hydrocarbon fuels, and if it goes outside the flammable range, unburned hydrogen that does not burn completely is discharged outside the engine. The presence of unburned hydrogen leads to a decrease in thermal efficiency. Technologies for promoting the combustion of mixtures containing hydrogen are disclosed in Patent Documents 1 and 2.

[0004] Patent Document 1 describes a control method for an engine that uses two types of fuel, hydrogen and hydrocarbon fuel. For example, Patent Document 1 describes that "by providing the spark plug at a position where it is hit more by the gas flowing into the cylinder from the second intake port than by the gas flowing into the cylinder from the first intake port, it is possible to prevent the hydrogen flowing in from the first intake port from coming into contact with the high-temperature spark plug."

[0005] Patent Document 2 describes a method for controlling an engine that uses two types of fuel, gas fuel and diesel fuel. For example, Patent Document 2 describes that "when it is determined that an abnormality has occurred in the engine, the control device performs control to instantly switch to diesel mode, and calculates the amount of liquid fuel to be supplied after instantly switching to diesel mode based on the engine speed and engine load." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-188990 A [Patent Document 2] JP 2020-23975 A Summary of the Invention [Problem to be solved by the invention]

[0007] It was thought that by using the method described in the above-mentioned Patent Document 1, it would be possible to reduce the probability of contact with the spark plug, which locally heats up in the combustion chamber, and reduce abnormal combustion during hydrogen combustion. However, when environmental conditions such as changes in the amount of hydrogen supply, intake temperature, and humidity change, or when operating conditions and conditions inside the engine's combustion chamber change over time, it may be difficult to avoid abnormal combustion. In addition, since hydrocarbons and hydrogen are supplied by separate injection valves, it becomes difficult for the hydrocarbon fuel and hydrogen to mix uniformly, and unburned hydrogen is more likely to occur under low temperature conditions. For these reasons, there are cases in which it is difficult to suppress abnormal combustion due to hydrogen and the emission of unburned hydrogen using Patent Document 1.

[0008] In addition, in the method described in Patent Document 2, when an ECU (Electronic Control Unit) judges abnormal combustion based on the engine torque and the mean effective pressure corresponding to the combustion torque, it is thought that it is possible to stop the supply of gas fuel and switch to a diesel combustion mode using only diesel fuel, thereby enabling combustion switching control that takes into account the influence of environmental changes. However, the method described in Patent Document 2 requires accurate torque information, which reduces the accuracy of judging abnormal combustion in the engine. In addition, since an in-cylinder pressure sensor is required for the ECU to grasp the mean effective pressure, a large cost is incurred for installing the in-cylinder pressure sensor to detect the combustion state. In addition, the combustion mode that the ECU switches to when an abnormality occurs in the engine is only the diesel combustion mode, and the ratio of gas fuel to diesel fuel in the abnormal state is not described in Patent Document 2, which means that the range in which the engine can be operated with gas fuel is narrowed.

[0009] The present invention has been made in consideration of the above circumstances, and has an object to correctly detect abnormal conditions in a hydrogen-mixed combustion engine and to appropriately control the mixture ratio of hydrogen supplied to the engine. [Means for solving the problem]

[0010] The electronic control device for hydrogen co-fuel combustion according to the present invention comprises: Light oil, heavy oil, biodiesel fuel, bio-oil fuel, or synthetic fuel a first fuel supply device that supplies hydrogen to the engine as a first fuel; Rich Gas The present invention controls the mixing ratio of hydrogen to be mixed and burned in the combustion chamber of a hydrogen-mixed combustion engine having a secondary fuel supply device that supplies a fuel containing a part of the above-mentioned fuel to the engine as a secondary fuel. This hydrogen co-fuel electronic control device controls the combustion of the engine. center of gravity A combustion timing detection unit that detects the timing; The engine has an abnormality mode determination unit that determines, as an abnormal mode, one or more abnormal states occurring in the engine, among misfire of the second fuel, reduction in hydrogen concentration of the second fuel, injector injection abnormality of the first fuel, actual compression ratio abnormality, component abnormality of the second fuel, knocking, premature ignition, and abnormality in the fuel injection system of the first fuel, based on the magnitude of a supply ratio of the second fuel calculated from the supply amount of the first fuel supplied by the first fuel supply device and the supply amount of the second fuel supplied by the second fuel supply device, which are detected by sensors provided in the engine, relative to a supply ratio threshold of the second fuel, delay or advancement of the combustion center timing calculated from a combustion timing threshold based on a normal combustion center timing relative to the supply ratio of the second fuel, and operating conditions. Abnormal state detection unit ,of Prepare. Effect of the Invention

[0011] According to the present invention, it is possible to detect combustion abnormalities in a hydrogen-mixed combustion engine without providing an in-cylinder pressure sensor, which enables the operation of a multi-fuel engine that uses hydrogen as part of the fuel at low cost. In addition, it is possible to supply the maximum amount of hydrogen to the engine because optimal control can be performed according to the abnormal state of the engine. Furthermore, it is possible to operate the engine for a long period of time because the abnormal state of the engine is resolved. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an engine system according to an embodiment of the present invention. [Diagram 2] 4 is a table showing physical property values ​​of fuel used in the engine system according to the embodiment of the present invention. [Diagram 3] 1 is a block diagram showing an example of the internal configuration of an electronic control device for hydrogen co-fuel combustion according to an embodiment of the present invention; [Figure 4] FIG. 2 is a diagram showing an example of a 100-cycle average of a combustion pressure waveform of an engine according to an embodiment of the present invention. [Diagram 5] FIG. 3 is a diagram showing an example of a combustion pressure waveform for each cycle according to one embodiment of the present invention. [Figure 6] 4 is a flowchart showing an example of a process for determining an abnormality in a combustion state of an engine and safely controlling the engine according to an embodiment of the present invention. [Figure 7] 1 is a diagram showing an example of the arrangement of an engine cylinder, a crankshaft, an electromagnetic pickup, and a controller according to an embodiment of the present invention; [Figure 8] FIG. 2 is a diagram showing an example of changes in rotation speed in an in-line four-cylinder engine according to an embodiment of the present invention. [Figure 9] FIG. 4 is a diagram showing the relationship between the peak timing of the rotation speed and the timing of the center of gravity of combustion according to one embodiment of the present invention. [Figure 10] 4 is a diagram showing a method of engine abnormality determination performed by an abnormal state detection unit according to one embodiment of the present invention; FIG. [Figure 11] 4 is a table showing the correspondence between abnormality modes and control modes of the engine according to one embodiment of the present invention. [Figure 12] FIG. 2 is a diagram showing the relationship between energy supply and demand and the amount of hydrogen that can be supplied according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant description will be omitted.

[0014] [First embodiment] 1 is a schematic diagram of an engine system 20. The engine system 20 includes an engine 18 that uses hydrogen as part of its fuel.

[0015] In the engine system 20, an injector 4 (an example of a fuel injection device) directly injects a hydrocarbon fuel, which is a first fuel, into a combustion chamber 2. The first fuel supplied to the combustion chamber 2 becomes hot and pressurized by compression of the piston 1, and the first fuel self-ignites and burns, generating torque in the piston 1. The up and down movement of the piston 1 is converted into the rotational movement of a crankshaft 17. A generator 50 is connected to the crankshaft 17, and generates electricity as the crankshaft 17 rotates.

[0016] A throttle valve 3 is provided in an intake pipe of the engine 18, and the amount of air taken from the intake pipe into the combustion chamber 2 is changed by adjusting the opening of the throttle valve 3 by the engine controller 11. The opening of the throttle valve 3 is detected by an opening sensor (not shown) and output to the engine controller 11.

[0017] Here, the first fuel and the second fuel will be described with reference to FIG. FIG. 2 is a table showing the physical property values ​​of the fuel used in the engine system 20. Figure 2 shows the flash point [K], boiling point [K], and kinematic viscosity of fuel at 30°C [mm 2 / s] and cetane number are shown.

[0018] The first fuel directly injected into the combustion chamber 2 is, for example, any one of light oil, heavy oil, biodiesel fuel (BDF: Bio Diesel Fuel (registered trademark)), bio-oil fuel, and synthetic fuel. Biodiesel fuel is a fuel with low kinetic viscosity that is made from organic resources (biomass) derived from renewable living organisms. Bio-oil fuel is also made from organic resources like biodiesel fuel, but since it is almost unprocessed, it has a higher kinetic viscosity than biodiesel fuel. Synthetic fuel is a fuel made from hydrogen and CO 2 It is a hydrocarbon fuel produced from

[0019] The engine system 20 includes fuel tanks 14, 15 that store at least two types of first fuel. The fuel tank 14 (an example of a high-viscosity fuel tank) stores, for example, heavy oil, bio-oil fuel, etc., that have a high kinetic viscosity. On the other hand, the fuel tank 15 (an example of a low-viscosity fuel tank) stores, for example, light oil, bio-diesel fuel, etc., that have a lower kinetic viscosity than the first fuel stored in the fuel tank 14.

[0020] The engine system 20 includes a switching unit 16 that switches between the fuel tanks 14 and 15 to supply the first fuel to the injector 4. The switching operation of the switching unit 16 is controlled by an instruction from the hydrogen-mixed combustion electronic control device 12. The hydrogen-mixed combustion electronic control device 12 notifies the engine controller 11 of the execution information of the switching operation. The switching unit 16 switches the supply source (one of the fuel tanks 14 and 15) of the first fuel. For example, when the engine 18 is normally used, the switching unit 16 outputs the first fuel supplied from the fuel tank 14 to the injector 4. When an abnormality occurs in the engine 18, the switching unit 16 switches the supply source of the first fuel from the fuel tank 14 to the fuel tank 15, and takes out the first fuel from the fuel tank 15 and supplies it to the injector 4. The injector 4 is an example of a first fuel supply device that supplies a hydrocarbon fuel as the first fuel to the engine (engine 18).

[0021] In this engine system 20, gas fuel, which is the second fuel, is supplied to an intake pipe of the engine 18 by a flow rate control device 6, and is mixed with air and supplied to the combustion chamber 2. In the combustion chamber 2, the first fuel and the second fuel are mixed. Then, due to the self-ignition combustion of the first fuel in the combustion chamber 2, the premixture of the second fuel and air is heated, and the second fuel is burned. Such combustion of the first fuel and the second fuel is referred to as "dual combustion" and will be described below.

[0022] The second fuel is a gas containing hydrogen as a fuel in part, such as hydrogen-rich gas, natural gas containing hydrogen in part, biogas containing hydrogen in part, synthetic gas containing hydrogen in part, ammonia, or reformed gas. The reformed gas is a gas obtained by reforming natural gas, biogas, biofuel such as ethanol, ammonia, or synthetic fuel. The hydrogen generator 5 is either an electrolysis device that decomposes water into hydrogen and oxygen, or a reformer with a catalyst inserted. The hydrogen generator 5 and the flow rate control device 6 are used as an example of a second fuel supply device that supplies fuel containing hydrogen in part to the engine (engine 18) as the second fuel.

[0023] When the hydrogen generator 5 is an electrolyzer, electricity generated by renewable energy obtained from a power generation system (not shown), such as solar power generation or wind power generation, is used as electricity supplied to the hydrogen generator 5. When the hydrogen generator 5 is a reformer, a hydrocarbon fuel or ammonia is supplied to the reformer, and one or more of exhaust heat from the engine 18 and coolant heat are supplied to the reformer.

[0024] The hydrogen co-firing electronic control device 12 may supply electricity to the reformer to operate it. Also, a hydrogen storage device (not shown) may be provided between the hydrogen generation device 5 and the flow rate adjustment device 6. The hydrogen storage device is either a hydrogen tank, a hydrogen storage alloy, or an organic hydride, and stores hydrogen generated by the hydrogen generation device 5 and can extract hydrogen upon request from the flow rate adjustment device 6. When a hydrogen storage alloy or an organic hydride is used as the hydrogen storage device, at least one of exhaust heat and coolant heat from the engine 18 is supplied to the hydrogen storage alloy or organic hydride.

[0025] The engine controller 11 includes an engine rotation sensor 7 and a cam rotation sensor 8 that detect the rotation timing of the engine 18. The engine controller 11 controls the injection timing of the second fuel injected from the injector 4 based on the detection results of the engine rotation sensor 7 and the cam rotation sensor 8. Furthermore, the engine controller 11 controls the injection timing of the second fuel based on the engine speed, torque, and a signal from an oxygen concentration sensor 10 in the exhaust gas. A part of the second fuel contains hydrogen. Therefore, the premixture of the second fuel and air is able to achieve dual combustion even when the ratio of air is more than the stoichiometric ratio, that is, under a high air excess ratio condition. Therefore, dual combustion is achieved by adding the second fuel to the intake air of the conventional diesel combustion engine 18.

[0026] The hydrogen co-fuel electronic control device 12 is a device that controls the mixture ratio of hydrogen to be co-fueled in the combustion chamber (combustion chamber 2) of the hydrogen co-fuel engine (engine 18) having the above-mentioned first fuel supply device and second fuel supply device. The hydrogen co-fuel electronic control device 12 detects the combustion timing of the engine 18 based on the detection results of the engine rotation sensor 7 and the cam rotation sensor 8. Then, the hydrogen co-fuel electronic control device 12 controls the flow rate adjustment device 6 and the hydrogen generation device 5 based on the detected combustion timing of the engine 18, and controls the flow rate of hydrogen supplied to the engine 18.

[0027] The energy management system 13 is provided separately from the engine system 20, and manages the total energy including the renewable energy and the fuel energy used in the engine system 20. For example, the energy management system 13 manages the total energy including the renewable energy generated by a solar power generation system or the like and the fuel energy of the engine system 20 controlled by the hydrogen-mixed combustion electronic control device 12. Therefore, one energy management system 13 can manage the energy of a plurality of engine systems 20. For example, the engine controller 11 and the hydrogen-mixed combustion electronic control device 12 are provided in a factory, and the energy management system 13 is provided in the same factory or on the cloud. Therefore, the energy management system 13 can also manage the energy of the engine controller 11 and the hydrogen-mixed combustion electronic control device 12 that are provided in locations distant from each other.

[0028] The hydrogen-mixed combustion electronic control device 12 has a function of communicating various information with the energy management system 13. The hydrogen-mixed combustion electronic control device 12 transmits and receives the supply ratio of the second fuel, the power output of the generator (generator 50) mechanically connected to the engine (engine 18), the amount of heat recovered from the exhaust heat of the engine (engine 18), and the abnormal state or control state of the engine (engine 18) through communication with the energy management system (energy management system 13) that controls renewable energy. Here, the supply ratio of the second fuel [%] is a value expressed as [(calorific value of the second fuel) / (calorific value of all fuels supplied to the engine 18)×100].

[0029] For example, the hydrogen-mixed combustion electronic control device 12 controls the hydrogen generation device 5 and the flow rate control device 6 based on the energy supply and demand balance of the energy management system 13. The hydrogen-mixed combustion electronic control device 12 also communicates to the energy management system 13 the state of the engine 18 detected by various sensors 19 (see FIG. 3 described later) already installed in the engine 18 and the execution details of the engine control. The energy management system 13 can formulate a hydrogen generation plan based on the information obtained from the hydrogen-mixed combustion electronic control device 12. The hydrogen co-fuel combustion electronic control device 12 may be mounted inside the engine controller 11.

[0030] FIG. 3 is a block diagram showing an example of the internal configuration of the hydrogen-mixed combustion electronic control device 12. As shown in FIG.

[0031] The hydrogen-mixed combustion electronic control device 12 includes a combustion timing detection unit 21 , a memory unit 22 , a threshold value determination unit 23 , an abnormal state detection unit 24 , and a control mode determination unit 25 .

[0032] The combustion timing detection unit (combustion timing detection unit 21) detects the combustion timing of the engine (engine 18). For example, the combustion timing detection unit 21 detects the combustion timing based on the detection results input from the sensors 19. The sensors 19 are various sensors provided in the existing engine 18, and include the engine rotation sensor 7 and the cam rotation sensors 8 and 9 shown in FIG. 1 as well as an opening sensor of the throttle valve 3. The cam rotation sensor 8 detects the rotation of the intake cam attached to the intake valve, and the cam rotation sensor 9 detects the rotation of the exhaust cam attached to the exhaust valve. The combustion timing detection unit (combustion timing detection unit 21) detects the combustion timing using at least one or more pieces of information output from an engine rotation sensor (engine rotation sensor 7) that detects the rotation change of the engine (engine 18) and information output from a cam sensor (cam rotation sensor 8) that detects the rotation change of a camshaft of the engine (engine 18).

[0033] Furthermore, in the engine system 20 according to this embodiment, it is not necessary to add a new sensor to the engine 18. The combustion timing detected by the combustion timing detection unit 21 is written as combustion timing time series data 22a in the memory unit 22. The combustion timing time series data 22a is data that stores the past combustion timing detected by the combustion timing detection unit 21 in chronological order.

[0034] The combustion timing detection unit 21 includes a combustion timing change rate calculation unit 21a. The combustion timing change rate calculation section (combustion timing change rate calculation section 21a) calculates the change rate of the combustion timing based on time series data of the combustion timing detected in the past (combustion timing time series data 22a).

[0035] The combustion timing detected by the combustion timing detection unit 21 is stored in chronological order in the storage unit 22. The combustion timing stored in chronological order in this manner is compiled as combustion timing chronological data 22a. Furthermore, the supply ratio threshold and the combustion timing threshold of the second fuel determined by the threshold determination unit 23 are stored as thresholds 22b in the memory unit 22. The supply ratio threshold and the combustion timing threshold are determined according to a relational expression shown in Fig. 10, which will be described later.

[0036] The threshold value determination unit 23 determines a threshold value (threshold value X shown in FIG. 10 to be described later) that is a reference for the abnormal state detection unit 24 to determine whether the engine 18 is in an abnormal state. 1 , X 2 , Y 1 , Y 2 ) is determined. The threshold value determination unit 23 uses engine control information input from the engine control controller 11 in order to determine the threshold value. Examples of the engine control information include the engine speed, the torque of the engine 18, the water temperature of the engine 18, the intake air temperature of the engine 18, the type of the first fuel, and the type of the second fuel. The threshold value determination unit (threshold value determination unit 23) determines the supply ratio threshold value and the combustion timing threshold value of the second fuel based on at least one of the engine speed (engine 18), the torque of the engine (engine 18), the speed of the generator (generator 50) mechanically connected to the engine (engine 18), the voltage of the generator (generator 50), the current of the generator (generator 50), the torque of the generator (generator 50), the water temperature of the engine (engine 18), the intake air temperature of the engine (engine 18), the type of the first fuel, and the type of the second fuel.

[0037] The abnormal state detection unit (abnormal state detection unit 24) detects an abnormal state that defines the type of abnormality occurring in the engine (engine 18) based on the combustion timing, the supply amount of the hydrocarbon fuel supplied by the first fuel supply device, and the second fuel supply ratio calculated from the supply amount of the second fuel supplied by the second fuel supply device. The combustion timing is detected by the combustion timing detection unit 21, and the supply amounts of the first fuel and the second fuel are input from sensors 19 already installed in the engine 18. The abnormal state detection unit (abnormal state detection unit 24) has an abnormal mode determination unit 24a that determines one or more abnormal states occurring in the engine (engine 18) as abnormal modes based on the magnitude of the supply ratio of the second fuel relative to the supply ratio threshold of the second fuel, and the delay or advance of the combustion timing calculated from the combustion timing threshold based on the normal combustion timing (the value of the relational expression Y shown in FIG. 10) relative to the supply ratio of the second fuel. The detection result of the abnormal state of the engine 18 detected by the abnormal state detection unit 24 is represented by an abnormality region number as shown in FIG. 10 and FIG. 11 described later. Then, the abnormal region number is output to the control mode determination unit 25.

[0038] The abnormal state detection unit 24 detects whether the state of the engine 18 is normal or abnormal. As shown in FIG. 10, which will be described later, in this embodiment, a plurality of threshold values ​​(X 1 , X 2 ) is set, and multiple thresholds (Y 1 , Y 2 ) are set, and these threshold values ​​are read out from the storage unit 22. The combustion center of gravity indicates the combustion phase where the combustion mass fraction is 50%, and the combustion center of gravity timing indicates the timing at which the combustion center of gravity occurs.

[0039] The combustion center timing (Y) calculated for the supply ratio of the second fuel is set to a threshold value (Y 1 , Y 2 ), it is determined that the engine 18 is in a normal state. 1 , Y 2) is outside the range, it is determined that the engine 18 is in an abnormal state. As shown in FIG. 10, the abnormal state of the engine 18 occurs when the combustion center timing with respect to the supply ratio of the second fuel is outside the threshold value (Y 1 ) or greater than the threshold (Y 2 ) or the supply ratio of the second fuel is below a threshold (X 1 ), less than threshold (X 1 ) or more threshold (X 2 ), less than threshold (X 2 ) and the above three types of abnormality. The six abnormal regions are identified by abnormal region numbers "1" to "6."

[0040] The abnormal state detection unit 24 includes an abnormality mode determination unit 24a as well as an individual cylinder abnormality determination unit 24b. The abnormality mode determination unit 24a determines whether the abnormal state of the engine 18 corresponds to any one of the abnormality modes represented by the abnormality region numbers shown in Fig. 10. The abnormality mode indicates the type of abnormality that has occurred in the engine 18 and is specified for each abnormality region number. Here, the abnormality mode determination unit 24a included in the abnormal state detection unit 24 determines the abnormality mode based on map information previously stored in the storage unit and the threshold value 22b read out from the storage unit 22.

[0041] The cylinder-by-cylinder abnormality determination unit (cylinder-by-cylinder abnormality determination unit 24b) determines an abnormal state for each cylinder of the engine (engine 18). Therefore, the cylinder-by-cylinder abnormality determination unit 24b can determine whether an abnormality has occurred in all cylinders or in only some cylinders. The abnormality mode determination unit 24a determines an abnormal state for each cylinder in which an abnormality has occurred.

[0042] The control mode determination unit (control mode determination unit 25) determines a control mode corresponding to the abnormal state detected by the abnormal state detection unit 24, controls the supply amount of hydrogen supplied by the second fuel supply device based on the control mode, and outputs the control mode to the engine control controller (engine control controller 11) that controls the engine (engine 18). Then, the engine control controller 11 and the hydrogen mixed combustion electronic control device 12 control the supply amount of the first fuel and the second fuel according to the control mode. The engine control controller 11 controls various actuators for operating the engine 18 according to the control mode. For example, the engine control controller 11 controls the switching unit 16 to switch the type of the first fuel supplied from the fuel tank 14 or 15, and to control the injection timing of the first fuel. The hydrogen mixed combustion electronic control device 12 controls the hydrogen generation device 5 to increase or decrease the amount of hydrogen generation, and controls the flow rate adjustment device 6 to adjust the hydrogen flow rate. Details of the control mode will be described later with reference to FIG. 11.

[0043] The control mode determination unit 25 also transmits the control mode to the energy management system 13. At this time, the abnormality mode determination result may be output from the abnormality state detection unit 24 to the energy management system 13. The energy management system 13 manages the current control state and abnormal state of the engine 18 based on the control mode received from the control mode determination unit 25.

[0044] Fig. 4 is a diagram showing an example of a 100-cycle average of the combustion pressure waveform of the engine 18. The horizontal axis of Fig. 4 represents the crank angle [deg. ATDC], and the vertical axis represents the in-cylinder pressure [MPa].

[0045] 4 shows the combustion pressure waveform, which is the average of 100 cycles of the combustion pressure measured when the hydrogen mixture ratio, which is the percentage of hydrogen in the total fuel supplied to the engine 18, is changed to 0%, 20%, 40%, 55%, and 60%. The combustion pressure waveform of the conventional engine 18 that does not use hydrogen is represented by a hydrogen mixture ratio of 0%. The combustion pressure waveforms for hydrogen mixture ratios of 0% and 20% are shown to be almost overlapping.

[0046] Figure 4 shows that as the hydrogen blend ratio increases, the combustion pressure rises earlier, and as the maximum pressure increases, the timing of the maximum pressure also becomes earlier. It can also be seen that the combustion pressure waveforms are significantly different when the hydrogen blend ratio is 55% and 60%. This difference in combustion pressure waveforms is due to the fact that when the hydrogen blend ratio is 60%, some of the 100 cycles include cycles in which abnormal combustion occurs.

[0047] Fig. 5 is a diagram showing an example of a combustion pressure waveform for each cycle, in which the horizontal axis represents time and the vertical axis represents combustion pressure.

[0048] An example of the combustion pressure waveform for each cycle when the hydrogen mixing ratio is 60% is shown in the upper part of Fig. 5. An enlarged view of the combustion pressure waveform included in the rectangular frame 30 at the left end of the combustion pressure waveform in Fig. 5 is shown in the lower part of Fig. 5. As shown in Fig. 4, when the hydrogen mixing ratio becomes 60%, the number of cycles in which abnormal combustion occurs increases.

[0049] The peak 31 of the combustion pressure waveform shown in the lower part of Fig. 5 shows the characteristics of the combustion pressure waveform when knocking occurs when the hydrogen mixing ratio is equal to or higher than a predetermined value at which abnormal combustion is likely to occur. When the hydrogen mixing ratio is equal to or higher than a predetermined value, the probability of such combustion occurring increases. In addition, the higher the temperature of the air supplied to the engine 18 and the temperature of the cooling water of the engine 18, the higher the probability of knocking occurring. Another type of abnormal combustion, hot surface ignition that occurs when contacting a high-temperature member inside the combustion chamber 2, is also more likely to occur under conditions where the hydrogen mixing ratio, intake air temperature, and cooling water temperature are high, similar to the increased probability of knocking occurring.

[0050] When such abnormal combustion occurs in the engine 18, the engine controller 11 cannot control the combustion timing of the engine 18 within the normal range, which deteriorates the thermal efficiency of the engine 18. Furthermore, the engine 18 may break down due to an increased timing of the pressure rise in the combustion chamber 2 or the generation of high-frequency pressure pulsations. Therefore, the hydrogen-mixed combustion electronic control device 12 needs to carry out adjustment control, such as reducing the amount of hydrogen supplied, before the engine 18 breaks down.

[0051] Such abnormal combustion in the engine 18 may occur due to environmental conditions such as changes in outside air temperature or transient changes in the engine 18. Therefore, the engine controller 11 and the hydrogen-mixed combustion electronic control device 12 need to detect the combustion in the engine 18 in real time and determine whether any abnormal combustion has occurred.

[0052] Another problem is that when the amount of the second fuel supplied is small and the hydrogen mixing ratio is low, a part of the supplied second fuel containing hydrogen does not burn in the combustion chamber 2 and is discharged directly to the outside of the engine 18. In this case, as shown in FIG. 4, no change is observed in the combustion pressure waveform when the hydrogen mixing ratio is 0% and 20%. Under such conditions, the second fuel containing hydrogen does not contribute to combustion, and the thermal efficiency of the engine 18 decreases. In addition, the discharge of unburned hydrogen to the outside of the engine 18 also causes safety problems.

[0053] And cases where hydrogen is discharged unburned are more likely to occur when the hydrogen mixture ratio is low. Hydrogen is a component that burns more easily under excess air conditions than hydrocarbon fuels, but when the excess air ratio of the mixture of the inhaled hydrogen and the intake air exceeds 8-10, the condition falls outside the flammable range. Therefore, when the supply amount of the secondary fuel is small, hydrogen is discharged unburned.

[0054] Regarding combustibility at low hydrogen mixing ratios, the hydrogen mixing ratio that is the threshold at which unburned hydrogen is discharged varies depending on the outside air temperature and the cooling water temperature. Furthermore, the intake air supercharging pressure and temperature vary depending on the operating conditions of the engine 18, such as the engine speed and torque, so the hydrogen mixing ratio that is the threshold also varies depending on the operating conditions of the engine 18. For these reasons, it is necessary to detect the combustion state in real time and grasp the combustibility of the hydrogen supplied to the combustion chamber 2.

[0055] Therefore, the inventors of the present application have invented a control flow shown in FIG. 6 in order to avoid abnormal combustion due to hydrogen and suppress unburned hydrogen in a hydrogen-mixed combustion engine 18 that uses hydrogen as part of the fuel. Fig. 6 is a flowchart showing an example of a process for determining whether there is an abnormality in the combustion state of the engine 18 and for safely controlling the engine 18. The process shown in Fig. 6 shows an example of a hydrogen mixing ratio control method performed by the hydrogen-mixed combustion electronic control device 12.

[0056] First, the combustion timing detection unit 21 detects the combustion state of the engine 18 in real time (S1). Then, the combustion timing detection unit 21 detects the combustion timing for each cycle as the combustion state of the engine 18 based on various detection results input from the sensors 19. At this time, the combustion timing change rate calculation unit 21a reads out the combustion timing time series data 22a from the memory unit 22 and can calculate the combustion timing change rate. Then, the combustion timing detection unit 21 outputs the detection result of the combustion state to the abnormal state detection unit 24.

[0057] Next, the abnormal state detection unit 24 performs an abnormality determination for the engine 18 (S2). Here, the abnormal state detection unit 24 can determine whether or not there is an abnormality in the engine 18 based on the supply ratio of the second fuel detected by the sensors 19, the combustion center timing detected by the combustion timing detection unit 21, and the threshold determined by the threshold determination unit 23. If the abnormal state detection unit 24 determines that there is no abnormality in the engine 18 (no abnormality in S2), the process returns to step S1 again and repeats the process of FIG. 6.

[0058] On the other hand, when the abnormal state detection unit 24 determines that there is an abnormality in the engine 18 (abnormality in S2), the abnormal mode determination unit 24a determines the abnormal mode based on the supply ratio of the second fuel, the timing of the center of combustion, and the threshold value (S3). The abnormal mode is determined based on which abnormal region number the combustion state of the engine 18 is included in. One abnormal mode may include multiple abnormal region numbers. Then, the abnormal mode determined by the abnormal mode determination unit 24a is output to the control mode determination unit 25.

[0059] The control mode determination unit 25 determines a control mode according to the abnormal mode determined by the abnormal mode determination unit 24a (S4). Then, the control mode determination unit 25 controls the hydrogen generation device 5, the flow rate control device 6, and the engine controller 11 according to the determined control mode. Therefore, the hydrogen generation device 5, the flow rate control device 6, and the engine controller 11 cooperate with each other according to the control mode so that the combustion in the engine 18 is in a normal state.

[0060] A method for detecting the combustion state in step S1 of the process shown in FIG. 6 will be described with reference to FIG. 7 is a diagram showing an example of the arrangement of the engine cylinders 41, the crankshaft 17, the electromagnetic pickup, and the controller. The four engine cylinders 41 shown in the diagram are numbered "1" to "4."

[0061] The method for detecting the combustion state according to this embodiment utilizes an existing engine rotation sensor 7 and a cam rotation sensor 8. The piston 1 and the cam are displaced in response to the rotation of the crankshaft 17. The engine rotation sensor 7 uses an electromagnetic pickup that detects the rotation angle of the crankshaft 17.

[0062] The engine control controller 11 and the hydrogen co-fuel electronic control device 12 acquire the rotation speed of the engine 18 using as a trigger the rising or falling edge of the pulse output in response to the rotation angle of the crankshaft 17 detected by the engine rotation sensor 7 and the rotation of the cam detected by the cam rotation sensor 8.

[0063] Next, the change in the rotation speed of the engine 18 will be described with reference to FIG. Fig. 8 is a diagram showing an example of changes in rotation speed in an in-line four-cylinder engine, in which the horizontal axis represents the crank angle and the vertical axis represents the rotation speed.

[0064] During one cycle of the engine 18, which is a crank angle of 720 degrees, the rotation speed changes with an amplitude of multiple peaks and valleys. Therefore, within one cycle (crank angles of 0 to 720°), the same number of amplitudes as the number of cylinders of the engine 18 connected to the crankshaft 17 on which the engine rotation sensor 7 is installed occur. In the figure, the change in the rotation speed is shown together with phase numbers 1 to 4 (denoted as phases #1 to #4) assigned to each cylinder.

[0065] As described above, the engine controller 11 can grasp the position of the amplitude based on the rising or falling edge of the pulse output from the cam rotation sensor 8. The engine controller 11 can then distinguish the cylinders from the edge count number of the engine rotation sensor 7 based on the edge output from the cam rotation sensor 8. The cylinder discrimination result is input from the engine controller 11 to the hydrogen-mixed combustion electronic control device 12, and is used, for example, for determining a threshold value by the threshold value determination unit 23, or for determining an abnormality for each cylinder by the cylinder-specific abnormality determination unit 24b. The engine controller 11 can grasp the peak position of the rotation speed of each cylinder from the edge count number. The peak position may be either the maximum value or the minimum value of the rotation speed.

[0066] As shown in Figure 8, the rotation speed changes due to torque changes caused by combustion in the engine 18. The timing of the rotation speed change also changes depending on the hydrogen mixture ratio. Specifically, when the hydrogen mixture ratio increases, the center of gravity of heat generation due to combustion advances, as shown by the white arrow in the figure.

[0067] Here, the relationship between the rotation speed and the center of gravity of the combustion will be described with reference to FIG. FIG. 9 is a diagram showing the relationship between the peak timing of the rotation speed and the timing of the center of gravity of combustion. The horizontal axis of FIG. 9 shows the peak timing of the rotation speed, and the vertical axis shows the timing of the center of gravity of combustion. The determination coefficient R 2 It is shown that the value is 0.99. The peak timing of the rotation speed shown in Fig. 9 corresponds to the value of the peak position of the rotation speed shown in Fig. 8.

[0068] As shown in Fig. 9, the rotation speed peak timing and the timing of the combustion center of gravity have a linear relationship. Therefore, the combustion timing detection unit 21 shown in Fig. 3 can grasp the change in the timing of the combustion center of gravity that accompanies a change in the supply ratio of the second fuel containing hydrogen, by grasping the rotation speed peak timing.

[0069] A combustion pressure sensor (not shown) may be attached to the engine 18. In this case, the combustion timing detection unit 21 can grasp the combustion center timing using a pressure signal output according to the combustion pressure detected by the combustion pressure sensor and the detection results of the engine rotation sensor 7 and the cam rotation sensor 8.

[0070] Next, a method for determining whether or not there is an abnormality in the engine 18 will be described with reference to FIGS. FIG. 10 is a diagram showing examples of abnormality region numbers of the engine 18 detected by the abnormal state detection unit 24. In FIG. FIG. 11 is a table showing the correspondence between the operating conditions of the engine 18, the phase determination results, the abnormality region numbers, the abnormality modes, and the control modes.

[0071] The abnormal mode determination section 24a of the abnormal state detection section 24 classifies abnormal combustion into abnormal regions 1 to 6 and determines the abnormal mode based on the relationship between the combustion gravity center timing Y estimated by the combustion timing detection section 21 from the peak timing of the rotation speed and the supply ratio X of the second fuel. The symbols and their respective relational expressions are explained below. Y=f 1 (X,N,T) X 1 =f 2 (T,N,T c ,Ti , F 1 , F 2 ) X 2 = f 3 (T, N, T c , T i , F 1 , F 2 ) Y 1 = f 4 (T, N, T c , T i , F 1 , F 2 , X) Y 2 = f 5 (T, N, T c , T i , F 1 , F 2 , X) Y: Combustion center of gravity timing X: Supply ratio of the second fuel X 1 , X 2 : Threshold value of the second fuel ratio for abnormal mode determination Y 1 , Y 2 : Threshold value of the fuel center of gravity timing for abnormal mode determination T: Torque of engine 18, torque of generator 50, or current value N: Rotational speed of engine 18, rotational speed of generator 50, or voltage value T c : Water temperature of engine 18 T i : Intake air temperature of engine 18 F 1 : Type of the first fuel F 2 : Type of the second fuel

[0072] In FIG. 10, the relationship between the supply ratio (X) of the second fuel and the combustion center of gravity timing (Y) is shown in a graph. Here, the threshold values X 1 , X 2 , and the relational expression Y = f 3 (X), abnormal regions 1 to 6 are set at timings slower or faster than a predetermined value. Here, the threshold value X 1 , X 2is the threshold for determining anomaly.

[0073] The threshold value determining unit 23 shown in FIG. 3 determines the engine speed (N), the torque (T) of the engine 18, the water temperature (T c ), engine 18 intake temperature (T i ), first fuel type (F 1 ), Secondary fuel type (F 2 ) to find the threshold value X 1 , X 2 The threshold value determination unit 23 determines the threshold value X by using the rotation speed or voltage value of the generator 50 mechanically connected to the crankshaft 17 instead of the engine rotation speed. 1 , X 2 Alternatively, the threshold value determining unit 23 may determine the threshold value X by using the torque or current value of a generator mechanically connected to the crankshaft 17 of the engine 18 instead of the torque of the engine 18. 1 , X 2 may be determined.

[0074] If the timing of the center of combustion (Y) is normal, the relational expression Y is a function Y=f of the supply ratio of the second fuel (X), the rotation speed N of the engine 18, and the torque T of the engine 18. 1 It is expressed as (X, N, T). Therefore, the abnormal state detection unit 24 calculates the threshold value Y from the value of the function Y. 1 More than or equal to the threshold Y 2 If an advance (over-advance) of less than threshold Y occurs, the combustion state is determined to be abnormal. 1 ,Y 2 are the engine speed (N), the torque of the engine 18 (T), and the water temperature of the engine 18 (T c ), engine 18 intake temperature (T i ), first fuel type (F 1 ), Secondary fuel type (F 2 ), is determined by the supply ratio of the second fuel (X).

[0075] In the abnormal regions 1, 3, and 5 shown in the figure, the timing of the center of gravity of combustion is related to the equation Y=f 3 The timing of the center of gravity of combustion represented by (X) is set to a threshold value of Y 1On the other hand, in the abnormal regions 2, 4, and 6 shown in the figure, the timing of the center of gravity of combustion is delayed from the timing of the center of gravity of combustion (Y) by the threshold value Y 2 This indicates an abnormality that occurs earlier than the timing when the signal is subtracted.

[0076] 11, the abnormality mode determination unit 24a determines the abnormality mode based on the engine operating conditions, the phase determination result, and the abnormality region number, and the control mode determination unit 25 determines the control mode based on the abnormality mode. The engine operating conditions described below include steady operation and fluctuating operation. The phase determination result includes phase retard abnormality and phase advance abnormality. Hereinafter, examples of each abnormal mode and the control mode corresponding to the abnormal mode will be described in order with reference to FIG.

[0077] <During normal operation: Only abnormal area 1 occurs> For example, during steady operation of the engine system 20 in which the rotation speed and load of the engine 18 are stable for several seconds, the abnormal state detection unit 24 may determine an abnormality in the combustion timing. In this manner, when the engine (engine 18) is steadily operating and a delay in the combustion timing occurs in which the supply ratio of the second fuel is less than the supply ratio threshold and is equal to or greater than the combustion timing threshold, and when the abnormal mode determination unit (abnormal mode determination unit 24a) determines, as an abnormal mode, that a delay in the combustion timing occurs in which the supply ratio of the second fuel is equal to or greater than the supply ratio threshold and is equal to or greater than the combustion timing threshold, the control mode determination unit (control mode determination unit 25) determines a control mode for implementing control to increase the supply amount of the second fuel to the second fuel supply device.

[0078] For example, the control mode determination unit 25 adjusts the supply amount of the second fuel by the flow rate control device 6, and the abnormality mode determination unit 24a grasps the abnormality region number. Therefore, in the extraction of the abnormality region number and abnormality mode determination process shown in Fig. 11, the control mode determination unit 25 changes the supply ratio (X) of the second fuel from 10 to 70%, for example, and determines the abnormality mode at the combustion center timing (Y) for each supply ratio of the second fuel.

[0079] Here, when the abnormality mode determination unit 24a determines that an abnormality exists only in the abnormality region 1, it can identify that the abnormal mode is a misfire of the second fuel because no abnormality occurs in the abnormality regions 3 and 5. In other words, the abnormality mode determination unit 24a can identify that the combustion timing being retarded from the predetermined angle is caused by a misfire of the second fuel.

[0080] Misfire of the second fuel occurs, for example, when the intake temperature of the engine 18 is low, when the humidity (amount of water) in the intake air is high, when the hydrogen mixing ratio in the second fuel is reduced, or when the ratio of inert gas is increased. When misfire of the second fuel occurs, the control mode determination unit 25 performs control to increase the supply amount of the second fuel. This control reduces the excess air ratio of the mixture supplied to the engine 18, and the second fuel containing hydrogen falls within the flammable range, so that misfire can be prevented and normal combustion mode can be restored.

[0081] <During normal operation: Occurs in abnormal regions 1, 3, and 5> When the engine (engine 18) is in steady operation, and the abnormality mode determination unit (abnormality mode determination unit 24a) determines that a delay in combustion timing that is equal to or greater than the combustion timing threshold has occurred as an abnormality mode, and the cylinder-specific abnormality determination unit (cylinder-specific abnormality determination unit 24b) detects the occurrence of an abnormality in all cylinders, the control mode determination unit (control mode determination unit 25) determines a control mode for implementing control to advance the injection timing of the first fuel. When the cylinder-specific abnormality determination unit (cylinder-specific abnormality determination unit 24b) detects the occurrence of an abnormality in some cylinders, the control mode determination unit (control mode determination unit 25) determines a control mode for implementing at least one of control to switch the type of the first fuel supplied from the first fuel supply device and control to set a flag for an abnormality in the injection device (injector 4) of the first fuel. The control to switch the type of the first fuel by the control mode determination unit 25 is performed for all cylinders.

[0082] In this way, during steady operation in which the engine 18 is in a stable rotation speed and load, the abnormal state detection unit 24 may determine that there is an abnormality in the combustion timing, and the individual cylinder abnormality determination unit 24b may confirm the occurrence of abnormal regions 1, 3, and 5 in all cylinders. Such an abnormality is caused by a decrease in the hydrogen concentration of the second fuel. Therefore, the control mode determination unit 25 performs control to advance the injection timing of the first fuel.

[0083] In addition, when the cylinder-by-cylinder abnormality determination unit 24b confirms the occurrence of the abnormality regions 1, 3, and 5 in some cylinders, it means that an injection abnormality of the injector of the first fuel has occurred in the cylinder in which the abnormality has occurred. Specifically, this abnormality occurs when the injector 4 of the first fuel cannot inject a predetermined injection amount at a predetermined injection timing.

[0084] Such an abnormality occurs due to deposits on the tip of the injector 4, as well as deterioration of the internal material of the injector 4. Therefore, the control mode determination unit 25 switches the first fuel. Specifically, the control mode determination unit 25 switches the currently used first fuel to one or more of low viscosity fuel, low boiling point fuel, and low oxygen content fuel. For example, when bio-oil fuel is used as the first fuel, the control mode determination unit 25 switches to BDF, synthetic fuel, or diesel. Also, for example, when BDF or synthetic fuel is used as the first fuel, the control mode determination unit 25 switches to diesel. By making the first fuel used in the engine 18 a fuel with a lower viscosity and boiling point than the fuel before switching, atomization and vaporization of the spray injected from the injector 4 are promoted, and deposits are less likely to occur at the tip of the injector 4.

[0085] Furthermore, when comparing the injection timing of the first fuel before and after the switching, the viscosity of the first fuel after the switching is lower than the viscosity of the first fuel before the switching, so the combustion speed of the first fuel after the switching is increased, and the combustion temperature of the first fuel can be increased. In addition, when the first fuel is switched to a low-oxygen-containing fuel, the heat value per unit volume of the fuel can be increased, so that the timing of the increase in the heat value of the first fuel supplied to the engine 18 is advanced during the injection timing of the first fuel. This advances the combustion timing, and the combustion temperature of the first fuel after the switching can be increased. In this way, the generation of deposits at the tip of the injector 4 is suppressed. In addition, it is possible to burn and reduce deposits that are currently present at the tip of the injector 4.

[0086] If the same abnormality mode (abnormality occurring in abnormality regions 1, 3, and 5) occurs even after the first fuel is switched, the abnormality state detection unit 24 sets a flag for an injector abnormality. Then, the abnormality state detection unit 24 notifies the user of the occurrence of the abnormality in the injector 4, and also notifies the engine controller 11 and the energy management system 13 of the occurrence of the abnormality in the injector 4.

[0087] <During normal operation: Occurs in abnormal regions 2, 4, and 6> There is a case where the abnormal state detection unit 24 detects an abnormality in the combustion timing during steady operation in which the engine speed and load are stable, and the cylinder-specific abnormality determination unit 24b confirms the occurrence of abnormal regions 2, 4, and 6 in all cylinders. In this case, the combustion timing detection unit 21 shown in FIG. 3 checks, using past time-series data, whether the timing abnormality has occurred due to a long-term change over time or a short-term transient change. Specifically, the combustion timing change rate calculation unit 21a of the combustion timing detection unit 21 calculates the change rate of the combustion timing by referring to the combustion timing time-series data 22a. Then, if the change rate of the combustion timing is less than a predetermined value, the combustion timing change rate calculation unit 21a determines that the change rate of the combustion timing is (1) a long-term change over time, and if the change rate of the combustion timing is equal to or greater than the predetermined value, the combustion timing change rate calculation unit 21a determines that ... (2) a short-term transient change.

[0088] (1) Long-term change over time The combustion timing changes over the long term due to an increase in the actual compression ratio in the engine 18 caused by the accumulation of impurities and the like in the combustion chamber 2 and the exhaust path. Specifically, when the engine 18 is operated for a predetermined period, ash, which is an inorganic compound caused by oil, gradually accumulates on the piston 1 and the exhaust pipe in the engine 18. In addition, deposits, which are the residues of combustion, accumulate on the injector 4, the exhaust valve, and the like. The accumulation of these ash and deposits in the engine 18 increases the actual compression ratio, which causes the combustion timing to advance and an abnormal timing advance to occur.

[0089] Therefore, when the engine (engine 18) is in steady operation and an early combustion timing that is less than the combustion timing threshold value occurs, and the change rate of the combustion timing is equal to or greater than the change rate threshold value determined by the threshold value determination unit (threshold value determination unit 23) (long-term change over time), and the abnormal mode determination unit (abnormal mode determination unit 24a) determines this as the abnormal mode, the control mode determination unit (control mode determination unit 25) determines a control mode for implementing at least one or more of the control to stop the supply of the second fuel from the second fuel supply device and the control to output a maintenance required notification to the second fuel supply device. For example, the control mode determination unit 25 performs (A) the switching control of the first fuel or (B) the supply amount control of the second fuel. The (A) switching control of the first fuel or (B) the supply amount control of the second fuel by the control mode determination unit 25 is performed for all cylinders.

[0090] If the abnormal timing advance is not avoided even after performing the above control, the abnormal state detection unit 24 notifies the user of the abnormal timing advance and also notifies the engine control controller 11 and the energy management system 13 of the abnormal timing advance.

[0091] (A) Switching control of the first fuel In the case of the first fuel switching control, the control mode determination unit 25 switches the first fuel currently in use to one or more of low viscosity fuel, low boiling point fuel, and low oxygen content fuel. Specifically, in the case of bio-oil fuel, the first fuel is switched to BDF, synthetic fuel, or diesel. Also, for example, if BDF or synthetic fuel is used as the first fuel, the control mode determination unit 25 switches to diesel.

[0092] The control mode determination unit 25 switches the first fuel used in the engine 18 to a fuel with a lower viscosity and boiling point than the fuel before the switch, which promotes atomization and vaporization of the spray injected from the injector 4. Therefore, at the same injection timing of the first fuel before and after the switch, the timing of self-ignition of the first fuel after the switch is advanced, and the combustion temperature is increased. In addition, when the first fuel is switched to a low-oxygen-containing fuel, the heat value per unit volume of the fuel can be increased, so that the timing of the increase in the heat value of the first fuel supplied to the engine 18 is advanced at the same injection timing of the first fuel. If the combustion timing of the first fuel after the switch can be advanced and the combustion temperature can be increased in this way, the generation of ash and deposits is suppressed. In addition, it is possible to burn and reduce deposits currently present at the tip of the injector 4.

[0093] (B) Secondary fuel supply control In the case of controlling the supply amount of the second fuel, the control mode determination unit 25 checks the relationship between the change over time of the combustion center timing and the supply ratio of the second fuel, and selects the supply ratio of the second fuel with a low rate of change in the combustion center timing. Then, the abnormal state detection unit 24 issues a maintenance notification for the engine 18 when the rate of change in the time series of the combustion center timing calculated by the combustion timing change rate calculation unit 21a exceeds a predetermined value. Specifically, the abnormal state detection unit 24 alerts the user to stop the engine 18 and to perform an overhaul of the engine 18.

[0094] (2) Short-term transitional changes When the combustion timing change rate calculation unit 21a determines that the change in the combustion timing is a short-term transient change, the change in the combustion timing occurs due to an abnormality in the composition of the second fuel. For example, the change in the combustion timing occurs when the hydrogen concentration of the second fuel is equal to or higher than a predetermined value, or when oxygen is mixed into the second fuel.

[0095] (Abnormal occurrence due to deterioration of sealing materials, etc.) For example, when the hydrogen generator 5 is an electrolysis device, the hydrogen generator 5 is a system that generates hydrogen and oxygen from water using electricity. Oxygen and hydrogen are generated in separate rooms, but when deterioration over time occurs in the sealing material at the boundary between the rooms, oxygen becomes mixed into the hydrogen. When oxygen becomes mixed into the second fuel, the oxygen concentration in the combustion chamber 2 increases, which increases the combustion speed, and as a result, the timing of the center of gravity of the combustion occurs earlier than specified.

[0096] In the case where the engine (engine 18) is in steady operation and the combustion timing is advanced to be less than the combustion timing threshold, and the rate of change of the combustion timing is greater than or equal to the change rate threshold determined by the threshold determination unit, End When the abnormality mode determination unit (abnormality mode determination unit 24a) determines that the abnormality mode is a short-term transient change, the control mode determination unit (control mode determination unit 25) determines a control mode for performing at least one of the following controls: control for switching the type of the first fuel supplied from the first fuel supply device, control for stopping the supply of the second fuel from the second fuel supply device, and control for outputting a notice of the need for maintenance of the engine (engine 18). For example, the control mode determination unit 25 performs control for stopping the supply of the second fuel when the rate of change of the combustion center timing calculated by the combustion timing change rate calculation unit 21a exceeds a predetermined value. Then, the abnormality state detection unit 24 notifies the user to perform maintenance on the hydrogen generation device 5.

[0097] (Abnormality caused by abnormal composition of second fuel) However, if an abnormality shown in abnormal regions 2, 4, and 6 occurs in a short period of time (transiently) rather than due to aging of the sealing material provided at the boundary between the oxygen and hydrogen chambers, it is considered that an abnormality in the composition of the second fuel has occurred. Such an abnormality is an event that occurs, for example, when the hydrogen concentration in the second fuel becomes higher than a predetermined value, or when oxygen is mixed into the second fuel.

[0098] For example, when the hydrogen generation device 5 is a water electrolysis device and an abnormality occurs in the water electrolysis device, a mixture of oxygen and hydrogen generated by the hydrogen generation device 5 is supplied to the engine 18. Since oxygen increases the combustion speed, the timing of the center of gravity of the combustion advances, resulting in the occurrence of the abnormalities shown in the abnormal regions 2, 4, and 6. When such an abnormality occurs, the control mode determination unit 25 must stop the supply of the second fuel and perform maintenance on the hydrogen supply device.

[0099] Although a water electrolysis device has been exemplified as the hydrogen generation device 5, the abnormality flag for the second fuel supply is set even when a predetermined amount of hydrogen or more is generated when a reformer is used as the hydrogen generation device 5. Therefore, the control mode determination unit 25 performs control in the reformer in the same manner as the above-mentioned control in the water electrolysis device.

[0100] <During normal operation: Occurs in abnormal region 6> When the combustion timing detection unit 21 determines that the combustion timing is abnormal during steady operation in which the rotation speed and power generation load of the engine 18 are stable, and when the cylinder-specific abnormality determination unit 24b confirms the occurrence of the abnormal region 6 in all cylinders, the abnormality mode determination unit 24a determines that an abnormal mode in which abnormal combustion such as knocking or early ignition occurs. In this way, when the engine (engine 18) is steadily operated, and the combustion timing is advanced so that the supply ratio of the second fuel is equal to or greater than the supply ratio threshold and is less than the combustion timing threshold, and the abnormality mode determination unit (abnormality mode determination unit 24a) determines that the engine is in an abnormal mode, the control mode determination unit (control mode determination unit 25) determines a control mode for performing at least one of control for reducing the supply amount of the second fuel to the second fuel supply device and control for delaying the injection timing of the injection device of the first fuel.

[0101] When the supply ratio of hydrogen in the second fuel is high, there is a case where premature ignition of hydrogen that comes into contact with hot parts in the combustion chamber 2 occurs. In addition, the mixture of the second fuel is ignited by the combustion of the first fuel, but when the hydrogen mixing ratio of the second fuel is high, the mixture may self-ignite and burn, causing knocking. When abnormal combustion occurs as described above, the control mode determination unit 25 can avoid knocking by implementing one or more controls of, for example, reducing the ratio of the second fuel when knocking occurs and retarding the injection timing of the first fuel. In addition, when premature ignition occurs, the control mode determination unit 25 can avoid premature ignition by a control mode that reduces the ratio of the second fuel and reduces the hydrogen mixing ratio in the combustion chamber.

[0102] <During fluctuating operation: occurs in any area> For example, during variable operation of the engine system 20 in which any one or more of the engine speed, the power generation load of the generator 50, and the supply amount of the second fuel change within a few seconds, an abnormality occurring in any of the regions is caused by low responsiveness of the injection control of the first fuel. Therefore, the abnormality mode determination unit 24a determines that such an abnormality is an abnormality in the fuel injection system of the first fuel. In the fuel injection system of the first fuel, the responsiveness of the adjustment of the fuel injection pressure is reduced due to, for example, a fuel filter or a clogged fuel pipe or an abnormality in the fuel pump, and as a result, an abnormality in the combustion timing occurs.

[0103] Therefore, when the engine (engine 18) is in variable operation and the abnormality mode determination unit (abnormality mode determination unit 24a) determines that a delay in combustion timing that is equal to or greater than the combustion timing threshold has occurred, or that an advance in combustion timing that is less than the combustion timing threshold has occurred, as an abnormal mode while the supply ratio of the second fuel is changing, the control mode determination unit (control mode determination unit 25) determines a control mode for performing at least one or more of control for switching the type of the first fuel supplied from the first fuel supply device and control for outputting a notice of the need for maintenance of the engine (engine 18). The control for switching the type of the first fuel by the control mode determination unit 25 is performed for all cylinders.

[0104] For example, when an abnormality occurs during variable operation, the control mode determination unit 25 switches the first fuel to a fuel having one or more of the following characteristics: a low viscosity fuel, a low boiling point fuel, and a low oxygen content fuel. For example, when bio-oil fuel is used as the first fuel, the control mode determination unit 25 switches to BDF, a synthetic fuel, or diesel. Also, when BDF or a synthetic fuel is used as the first fuel, the control mode determination unit 25 switches to diesel. By making the first fuel used in the engine 18 a fuel with a lower viscosity and boiling point than the fuel before the switch, the responsiveness of the discharge amount control by the fuel pump is increased, and the responsiveness of the adjustment of the fuel injection pressure is improved.

[0105] In addition, by switching the first fuel to a low-oxygen-containing fuel, the calorific value per unit volume of the fuel can be increased, so that the discharge amount from the fuel pump can be reduced, and as a result, the responsiveness of the adjustment of the fuel injection pressure can be improved. In addition, by using a low-oxygen-containing fuel, deterioration of the sealing material in the fuel pipe and generation of impurities around the fuel pump can be suppressed, and as a result, a decrease in the responsiveness of the adjustment of the fuel injection pressure can be suppressed.

[0106] If the same abnormal mode occurs within a specified period even after the control mode determination unit 25 switches the first fuel as described above, the abnormal state detection unit 24 sets a fuel injection system abnormality flag and notifies the user of the occurrence of an abnormality in the fuel injection system, and also notifies the engine control controller 11 and the energy management system 13 of the occurrence of an abnormality in the fuel injection system.

[0107] For this reason, when an abnormality is detected in the engine 18, a transition to a maintenance mode is performed. The maintenance mode is an operation mode for safely operating the engine 18. For example, at least one of the following processes is performed in the maintenance mode: the abnormal state detection unit 24 notifies the user of engine failure maintenance, the control mode determination unit 25 cuts off the supply of hydrogen to the engine 18, and the control mode determination unit 25 reduces the engine output.

[0108] (Energy management system operation) Here, the control operation of the energy management system 13 will be described. As described above, the hydrogen-mixed combustion electronic control device 12 has a function of communicating information with the energy management system 13, including renewable energy. Based on the energy supply and demand balance of the energy management system 13, the hydrogen-mixed combustion electronic control device 12 controls the flow rate regulator 6, the hydrogen generator 5, the switching unit 16, the torque and rotation speed of the engine 18, and the torque or current value and rotation speed of the generator 50.

[0109] Fig. 12 is a diagram showing the relationship between energy supply and demand and the amount of hydrogen that can be supplied. The horizontal axis of Fig. 12 represents time.

[0110] As shown in the energy supply and demand graph in the upper part of Fig. 12, renewable energy sources such as solar power generation that are dependent on the weather (solid line) fluctuate in the amount of power generated, and there are cases where they generate more power than the energy demand (dashed line). In addition, there are time periods when the amount of renewable energy generated that exceeds the energy demand becomes surplus power, and hydrogen is generated from the surplus power using the hydrogen generation device 5. Therefore, as shown in the graph of the amount of hydrogen that can be supplied in the lower part of Fig. 12, the greater the surplus power, the greater the amount of hydrogen that can be supplied.

[0111] The hydrogen co-fuel electronic control device 12 communicates the state of the engine system 20 and the details of the control to be performed to the energy management system 13, thereby determining the amount of hydrogen that can be accepted by the engine 18 (referred to as the "hydrogen acceptable amount"). The energy management system 13 can determine the amount of hydrogen to be generated by the hydrogen generation device 5 based on the hydrogen supplyable amount determined by the energy supply and demand balance and the hydrogen acceptable amount on the engine 18 side.

[0112] In the hydrogen-mixed combustion electronic control device 12 according to the embodiment described above, the timing of the center of gravity of combustion is detected in real time based on information detected by the existing sensors 19 attached to the engine 18, and various combustion abnormality modes are determined when an abnormality occurs in the engine 18. Then, a control mode for controlling the engine system 20 is determined based on the determined abnormality mode. The control mode implements various control methods according to the combustion state, such as control to adjust the hydrogen mixture ratio, as well as control to transition to a maintenance mode. For example, the hydrogen-mixed combustion electronic control device 12 reduces the amount of hydrogen supplied to the engine 18 or reduces the output of the engine 18. In this case, the hydrogen-mixed combustion electronic control device 12 maximizes the amount of hydrogen supplied to the engine 18 without putting a burden on the engine 18. The hydrogen-mixed combustion electronic control device 12 can efficiently control the engine 18 and enable the engine 18 to be used for a long period of time.

[0113] Furthermore, if an abnormality occurs in the engine 18, the hydrogen-mixed combustion electronic control device 12 outputs a notification to the user that maintenance is required for the engine 18. This allows the user to inspect, overhaul, etc. the engine 18, and to quickly resolve the abnormality in the engine 18.

[0114] The combustion state of the engine 18 is determined using information detected by sensors 19 already installed in the engine system 20. This eliminates the need to modify the engine 18 and install a new in-cylinder pressure sensor. In addition, since no in-cylinder pressure sensor is installed in the combustion chamber 2, there is no need to replace a deteriorated in-cylinder pressure sensor in the combustion chamber 2.

[0115] Furthermore, the combustion timing detected by the combustion timing detection unit 21 does not have to be limited to the combustion center timing that indicates the combustion phase where the combustion mass fraction is 50%. The combustion timing detection unit 21 may detect any combustion timing, and the threshold determination unit 23 may determine the threshold based on the any combustion timing.

[0116] [Variations] The engine system 20 according to the embodiment described above is a stationary engine system installed in a factory, for example, but may be an engine system mounted on a vehicle. Also, the engine system 20 may be applied to an engine control unit (ECU).

[0117] 10 may be obtained by machine learning. The relational equation, the supply ratio threshold, and the combustion timing threshold obtained by machine learning in one engine system 20 may be applied to another engine system 20, thereby improving the performance of the multiple engine systems 20 managed by the energy management system 13.

[0118] In addition, in FIG. 10, six abnormality regions representing abnormality 1 to abnormality 6 are provided, but the abnormality contents may be divided more finely or broadly. For example, by setting one supply rate threshold, four abnormality regions can be provided. By dividing the abnormality regions roughly, the control of the engine 18 can be accelerated. Furthermore, by setting three supply rate thresholds, eight abnormality regions can be provided. By dividing the abnormality regions finely, the engine 18 can be controlled more finely.

[0119] Incidentally, the present invention is not limited to the above-described embodiment, and it goes without saying that various other applications and modifications are possible without departing from the gist of the present invention as set forth in the claims. For example, the above-mentioned embodiment describes the system configuration in detail and specifically in order to explain the present invention in an easily understandable manner, and is not necessarily limited to a system having all of the described configurations. In addition, it is also possible to add, delete, or replace part of the configuration of the present embodiment with other configurations. In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other. [Explanation of symbols]

[0120] 1...piston, 2...combustion chamber, 4...injector, 5...hydrogen generation device, 6...flow rate adjustment device, 11...engine controller, 12...electronic control device for hydrogen co-fuel combustion, 13...energy management system, 14, 15...fuel tank, 16...switching unit, 18...engine, 20...engine system, 21...combustion timing detection unit, 21a...combustion timing change rate calculation unit, 22...storage unit, 22a...combustion timing time series data, 22b...threshold value, 23...threshold value determination unit, 24...abnormal state detection unit, 24a...abnormal mode determination unit, 24b...cylinder-specific abnormality determination unit, 25...control mode determination unit

Claims

1. An electronic control device for hydrogen co-fuel combustion, the electronic control device controlling the mixing ratio of hydrogen to be co-fueled in a combustion chamber of a hydrogen co-fuel engine having a first fuel supply device that supplies a first fuel to the engine, which is any one of light oil, heavy oil, biodiesel fuel, bio-oil fuel, and synthetic fuel, and a second fuel supply device that supplies a second fuel to the engine, which is a fuel that partially contains hydrogen-rich gas, a combustion timing detection unit that detects a combustion center timing of the engine; and an abnormality mode determination unit that determines, as an abnormal mode, any one or more abnormal states occurring in the engine, including a misfire of the second fuel, a decrease in a hydrogen concentration of the second fuel, an injector injection abnormality of the first fuel, an actual compression ratio abnormality, a component abnormality of the second fuel, knocking, pre-ignition, and an abnormality in a fuel injection system of the first fuel, based on a magnitude of a supply ratio of the second fuel calculated from a supply amount of the first fuel supplied by the first fuel supply device and a supply amount of the second fuel supplied by the second fuel supply device, which are detected by sensors provided in the engine, relative to a supply ratio threshold of the second fuel, a delay or advance of the combustion center timing calculated from a combustion timing threshold based on a normal combustion center timing for the supply ratio of the second fuel, and operating conditions. Electronic control device for hydrogen co-firing.

2. the abnormal state detection unit has a cylinder-by-cylinder abnormality determination unit that determines the abnormal state for each cylinder of the engine, the combustion timing detection unit has a combustion timing change rate calculation unit that calculates a change rate of the combustion center timing based on time series data of the combustion center timing detected in the past, a control mode determination unit that determines a control mode based on the abnormal state for each cylinder of the engine, the rate of change in the combustion center timing, and the abnormal mode, controls the supply amount of the hydrogen supplied by the second fuel supply device based on the control mode, and outputs the control mode to an engine controller that controls the engine. The electronic control device for hydrogen co-fuel combustion according to claim 1.

3. When the engine is in a steady operation, a delay in the combustion center timing occurs such that the supply rate of the second fuel is less than the supply rate threshold and is equal to or greater than the combustion timing threshold, and when the abnormality mode determination unit determines, as the abnormal mode, that a delay in the combustion center timing occurs such that the supply rate of the second fuel is equal to or greater than the supply rate threshold and is equal to or greater than the combustion timing threshold, the control mode determination unit determines the control mode for performing control to increase the supply amount of the second fuel to the second fuel supply device. The electronic control device for hydrogen co-fuel combustion according to claim 2.

4. When the engine is in a steady operation, and an advancement of the combustion center timing occurs such that the supply ratio of the second fuel is equal to or greater than the supply ratio threshold and is less than the combustion timing threshold, and when the abnormality mode determination unit determines, as the abnormal mode, that an advancement of the combustion center timing such that the supply ratio of the second fuel is less than the supply ratio threshold and is less than the combustion timing threshold has not occurred, the control mode determination unit determines the control mode for performing at least one of control for reducing the supply amount of the second fuel to the second fuel supply device and control for delaying the injection timing of the injection device of the first fuel. The electronic control device for hydrogen co-fuel combustion according to claim 2.

5. When the engine is in a steady operation and the abnormality mode determination unit determines that a delay in the combustion center timing that is equal to or greater than the combustion timing threshold has occurred as the abnormal mode, and when the cylinder abnormality determination unit detects the occurrence of an abnormality in all of the cylinders, the control mode determination unit determines the control mode for performing control to advance the injection timing of the first fuel, When the occurrence of an abnormality in some of the cylinders is detected by the individual cylinder abnormality determination unit, the control mode determination unit determines the control mode for performing at least one of control for switching the type of the first fuel supplied from the first fuel supply device and control for setting a flag for an abnormality in an injection device of the first fuel. The electronic control device for hydrogen co-fuel combustion according to claim 2.

6. When the engine is in a steady operation, and the abnormality mode determination unit determines that an advancement of the combustion center timing that falls below the combustion timing threshold has occurred as the abnormal mode, and when a rate of change of the combustion center timing is equal to or greater than a rate of change threshold, the control mode determination unit determines the control mode for performing at least one of control for stopping the supply of the second fuel from the second fuel supply device and control for outputting a maintenance required notice to the second fuel supply device. The electronic control device for hydrogen co-fuel combustion according to claim 2.

7. When the engine is in a steady operation and the abnormal mode determination unit determines, as the abnormal mode, that the advancement of the combustion center timing that falls below the combustion timing threshold has occurred, and when the abnormal mode determination unit determines, as the abnormal mode, that a rate of change of the combustion center timing is less than a rate of change threshold, the control mode determination unit determines the control mode for performing at least one or more of control for switching the type of the first fuel supplied from the first fuel supply device, control for stopping the supply of the second fuel from the second fuel supply device, and control for outputting a maintenance requirement notice for the engine. The electronic control device for hydrogen co-fuel combustion according to claim 2.

8. When the abnormality mode determination unit determines, as the abnormal mode, that a delay in the combustion center timing that becomes equal to or greater than the combustion timing threshold value has occurred or that an advance in the combustion center timing that becomes less than the combustion timing threshold value has occurred while the engine is being variably operated and the supply ratio of the second fuel is changing, the control mode determination unit determines the control mode for performing at least one or more of control for switching the type of the first fuel supplied from the first fuel supply device and control for outputting a maintenance requirement notice for the engine. The electronic control device for hydrogen co-fuel combustion according to claim 2.

9. The combustion timing detection unit detects the combustion center timing using at least one of information output from an engine rotation sensor that detects a rotation change of the engine and information output from a cam sensor that detects a rotation change of a camshaft of the engine. The electronic control device for hydrogen co-fuel combustion according to any one of claims 1 to 8.

10. The supply ratio of the second fuel, the power output of a generator mechanically connected to the engine, the amount of heat recovered from the exhaust heat of the engine, and the abnormal state or control state of the engine are transmitted and received through communication with an energy management system that controls renewable energy. The electronic control device for hydrogen co-fuel combustion according to any one of claims 1 to 8.

11. A hydrogen mixture ratio control method for controlling the mixture ratio of hydrogen to be mixed and burned in a combustion chamber of a hydrogen mixed combustion engine having a first fuel supply device which supplies any one of light oil, heavy oil, biodiesel fuel, bio-oil fuel, and synthetic fuel to an engine as a first fuel, and a second fuel supply device which supplies a fuel partially containing hydrogen-rich gas to the engine as a second fuel, comprising: A process for detecting a combustion center timing of the engine; and determining, as an abnormal mode, any one or more abnormal states occurring in the engine, including misfire of the second fuel, a decrease in hydrogen concentration of the second fuel, abnormal injection of the first fuel, abnormal actual compression ratio, abnormal component of the second fuel, knocking, early ignition, and abnormality in a fuel injection system of the first fuel, based on a magnitude of a supply ratio of the second fuel calculated from a supply amount of the first fuel supplied by the first fuel supply device and a supply amount of the second fuel supplied by the second fuel supply device, which are detected by sensors provided in the engine, relative to a supply ratio threshold of the second fuel, a delay or advance of the combustion center timing calculated from a combustion timing threshold based on a normal combustion center timing for the supply ratio of the second fuel, and operating conditions. Hydrogen blend ratio control method.

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