Control device and method for internal combustion engine

Abstract

To suppress generation of harmful substances when using ammonia as fuel in a control device and method for an internal combustion engine.SOLUTION: In an internal combustion engine having a fuel supply passage for supplying ammonia as fuel to a combustion chamber and a reformer that reforms ammonia to hydrogen by using heat of exhaust gas, when a load is raised by increasing the amount of ammonia, if thermal efficiency deteriorates, ignition timing is delayed, and when a concentration of dinitrogen monoxide in exhaust gas or a correlation value correlated with the concentration of the dinitrogen monoxide in exhaust gas reaches a preset determination value, the delay of the ignition timing is finished.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control system and method for an internal combustion engine. [Background technology]

[0002] Internal combustion engines are powered by combusting fuel supplied to the combustion chamber, extracting the chemical energy of the fuel and converting it into kinetic energy. In recent years, carbon-free fuels such as ammonia and hydrogen, which do not produce carbon dioxide when burned, have been considered for use in internal combustion engines. However, ammonia has poor combustibility, so it has been proposed to use it in combination with a fuel with good combustibility. For example, a reformer is installed in the fuel supply path, and part of the ammonia fuel is converted into hydrogen gas, and the ammonia containing hydrogen gas is supplied to the combustion chamber.

[0003] A control device for an internal combustion engine that uses two types of fuel is disclosed in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 3-51179 Summary of the Invention [Problem to be solved by the invention]

[0005] The reformer uses heat from the internal combustion engine to reform ammonia. When the internal combustion engine is running at low load, the exhaust gas temperature is low, resulting in a low rate of reforming ammonia into hydrogen. However, when the internal combustion engine is running at high load, the exhaust gas temperature rises and the rate of reforming increases. Therefore, when an internal combustion engine equipped with a reformer is installed on a ship, the rate of reforming gradually increases as the load increases from anchorage at port to offshore navigation, and the ratio of hydrogen to ammonia increases. While mixing hydrogen with ammonia increases thermal efficiency, once a certain hydrogen ratio is exceeded, the thermal efficiency decreases. Retarding the ignition timing of the internal combustion engine is considered as a solution, but this increases the emissions of nitrous oxide (N2O), which has a high global warming potential.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a control device and method for an internal combustion engine that suppresses the generation of harmful substances when ammonia is used as fuel. [Means for solving the problem]

[0007] In order to achieve the above object, the control device for an internal combustion engine of the present disclosure, in an internal combustion engine having a fuel supply path that supplies ammonia as fuel to a combustion chamber and having a reformer that reforms the ammonia into hydrogen using the heat of exhaust gas, retards the ignition timing if thermal efficiency decreases when the amount of ammonia is increased to increase the load, and ends retarding the ignition timing when the concentration of nitrous oxide in the exhaust gas or a correlation value correlated to the concentration of nitrous oxide in the exhaust gas reaches a predetermined judgment value.

[0008] Furthermore, the control method for an internal combustion engine of the present disclosure includes, in an internal combustion engine having a fuel supply path that supplies ammonia as fuel to a combustion chamber and having a reformer that reforms the ammonia into hydrogen using the heat of exhaust gas, the control method includes the steps of increasing the amount of ammonia to increase the load, retarding the ignition timing when the thermal efficiency decreases, and ending the retardation of the ignition timing when the concentration of nitrous oxide in the exhaust gas or a correlation value that is correlated to the concentration of nitrous oxide in the exhaust gas reaches a predetermined judgment value. [Effects of the Invention]

[0009] According to the control device and method for an internal combustion engine disclosed herein, it is possible to suppress the generation of harmful substances when ammonia is used as fuel. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the control device for an internal combustion engine according to this embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing a control map of the reformer. [Figure 3] FIG. 3 is a flowchart showing a control method for an internal combustion engine. [Figure 4] FIG. 4 is a time chart showing a control method for an internal combustion engine. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0012] <Internal combustion engine> FIG. 1 is a block diagram showing the control device for an internal combustion engine according to this embodiment.

[0013] As shown in FIG. 1, the internal combustion engine 10 includes an internal combustion engine body 11, an intake path 12, an exhaust path 13, a fuel supply path 14, a supercharger 15, a reformer 16, a fuel cooler 17, and a control device 18.

[0014] The internal combustion engine body 11 is, for example, a multi-cylinder engine. The internal combustion engine body 11 has a plurality of combustion chambers 21. In each combustion chamber 21, a downstream end of an intake passage 12 is connected to an intake port (not shown), and an upstream end of an exhaust passage 13 is connected to an exhaust port (not shown). The internal combustion engine body 11 also has a spark plug 22. The spark plug 22 ignites an air-fuel mixture in the combustion chamber 21. Furthermore, a throttle valve 23 is provided in the intake passage 12. The throttle valve 23 supplies the air-fuel mixture to the combustion chamber 21 by opening, and adjusts the flow rate of the air-fuel mixture (fuel) supplied to the combustion chamber 21 by adjusting its opening.

[0015] The downstream end of the fuel supply path 14 is connected to the intake path 12. The fuel supply path 14 supplies fuel to the intake path 12. The fuel supply path 14 is provided with a fuel tank 31 and a fuel pump 32. The fuel supply path 14 is connected to the fuel tank 31 at its upstream end and to the fuel pump 32 at its midpoint. The fuel tank 31 stores fuel, and the fuel pump 32 pressurizes the fuel stored in the fuel tank 31 to a predetermined pressure.

[0016] The fuel is ammonia, which does not burn well. Ammonia is a carbon-free fuel that does not produce carbon dioxide, unlike hydrocarbon fuels.

[0017] The intake path 12 draws in air from the outside. The fuel supply path 14 supplies fuel pressurized by a fuel pump 32 to the intake path 12. When the throttle valve 24 is open, a mixture of air and fuel from the intake path 12 is supplied to the combustion chamber 21 from the intake port. In this case, the intake path 12 also serves as part of the fuel supply path 14. When the mixture in the combustion chamber 21 is ignited by the spark plug 22, the mixture burns and drives the internal combustion engine body 11. Combustion gas produced by the combustion of the mixture in the combustion chamber 21, i.e., exhaust gas, is discharged from the exhaust port to the exhaust path 13.

[0018] The turbocharger 15 is configured by connecting a compressor 41 and a turbine 42 so that they rotate integrally via a rotary shaft 43. The compressor 41 is disposed in the intake path 12, and the turbine 42 is disposed in the exhaust path 13. In the turbocharger 15, the turbine 42 is rotated by exhaust gas flowing through the exhaust path 13, and the rotation of the turbine 42 is transmitted to the compressor 41 via the rotary shaft 43, causing the compressor 41 to rotate. The compressor 41 compresses the air-fuel mixture and supplies it to the combustion chamber 21.

[0019] Although the internal combustion engine 10 is configured to include the turbocharger 15, the turbocharger 15 may not be required. The exhaust path 13 may be provided with an exhaust bypass device. The exhaust bypass device is configured by providing a wastegate valve in a bypass passage that bypasses the turbine 42. The exhaust bypass device opens and closes the bypass passage in accordance with the intake pressure in the intake passage, thereby adjusting the amount of exhaust gas supplied to the turbine 42.

[0020] The reformer 16 is disposed in the fuel supply path 14. The reformer 16 reforms ammonia as fuel to produce hydrogen. The reformer 16 is a heat exchanger. The downstream end of the exhaust path 13 is disposed inside the reformer 16. The reformer 16 exchanges heat between the ammonia flowing in the fuel supply path 14 and the exhaust gas flowing in the exhaust path 13. That is, the ammonia flowing in the fuel supply path 14 is reformed by being heated by the exhaust gas flowing in the exhaust path 13, and hydrogen is produced. In addition, the fuel supply path 14 is provided with a bypass path 51 that bypasses the reformer 16. A switch valve 52 is provided in the fuel supply path 14 at a branch point between the fuel supply path 14 and the bypass path 51, upstream of the reformer 16.

[0021] The reformer 16 is heated by the exhaust gas flowing through the exhaust path 13. When the fuel supply path 14 and the reformer 16 are connected by the switching valve 52, the ammonia in the fuel supply path 14 is supplied to the reformer 16, and the reformer 16 operates. On the other hand, when the fuel supply path 14 is connected to the bypass path 51, the ammonia in the fuel supply path 14 is not supplied to the reformer 16 but flows into the bypass path 51, and the reformer 16 does not operate. In other words, by switching the switching valve 52, the reforming rate of the ammonia by the reformer 16, that is, the mixing rate of hydrogen in the fuel (ammonia), can be adjusted.

[0022] The fuel cooler 17 is disposed in the fuel supply path 14. The fuel cooler 17 cools the fuel flowing through the fuel supply path 14, i.e., the ammonia. The fuel cooler 17 particularly cools the ammonia that has passed through the reformer 16. The fuel cooler 17 is a heat exchanger. The fuel cooler 17 exchanges heat between the ammonia flowing through the fuel supply path 14 and the cooling water flowing through the cooling path 53. In other words, the ammonia flowing through the fuel supply path 14 is cooled by the cooling water flowing through the cooling path 53. The fuel cooler 17 may be disposed as needed, or may not be provided.

[0023] <Control device for internal combustion engine> The control device 18 controls the operation of the internal combustion engine 10. The control device 18 is connected to the throttle valve 23, the spark plug 22, and the switching valve 52. The control device 18 can adjust the flow rate of the mixture (fuel) supplied to the combustion chamber 21 by adjusting the opening of the throttle valve 23. The control device 18 can advance or retard the ignition timing by controlling the ignition timing of the spark plug 22. The control device 18 can adjust the reforming rate of ammonia by the reformer 16 by controlling the switching of the switching valve 52.

[0024] A temperature sensor 61 and a concentration sensor 62 are provided in the exhaust path 13 between the turbine 42 and the reformer 16. The temperature sensor 61 measures the temperature of the exhaust gas flowing through the exhaust path 13. The concentration sensor 62 measures the concentration of nitrous oxide in the exhaust gas flowing through the exhaust path 13. The temperature sensor 61 and the concentration sensor 62 are connected to the control device 18. The temperature sensor 61 outputs the measured temperature of the exhaust gas to the control device 18, and the concentration sensor 62 outputs the measured concentration of nitrous oxide in the exhaust gas to the control device 18. Here, nitrous oxide is a type of nitrogen oxide (NOx).

[0025] <Reformer control> FIG. 2 is an explanatory diagram showing a control map of the reformer.

[0026] 1 and 2, the control device 18 controls the switching of the switching valve 52 based on the operating state of the internal combustion engine 10, and is able to adjust the reforming rate of ammonia by the reformer 16. The control device 18 receives as input the temperature of the exhaust gas measured by a temperature sensor 61 and the concentration of nitrous oxide in the exhaust gas measured by a concentration sensor 62. The control device 18 controls the operation of the reformer 16, i.e., the switching valve 52, based on a control map based on the temperature of the exhaust gas and the flow rate of ammonia flowing into the reformer 16.

[0027] The control map shows the relationship between the temperature of the exhaust gas and the flow rate of ammonia. In the control map, the higher the temperature of the exhaust gas and the lower the flow rate of ammonia, the higher the reforming rate by the reformer 16. On the other hand, in the control map, the lower the temperature of the exhaust gas and the higher the flow rate of ammonia, the lower the reforming rate by the reformer 16. The control device 18 sets the reforming rate of the reformer 16 based on the control map so that the concentration of nitrous oxide in the exhaust gas measured by the concentration sensor 62 does not exceed the emission regulation value.

[0028] <Ignition timing control> As shown in FIG. 1, when the load (output) of the internal combustion engine body 11 is increased by increasing the amount of ammonia, the control device 18 retards the ignition timing if the thermal efficiency decreases, and ends the retardation of the ignition timing when the concentration of nitrous oxide in the exhaust gas or a correlation value correlated to the concentration of nitrous oxide in the exhaust gas reaches a predetermined judgment value.

[0029] Here, the determination value is a value lower than the emission regulation value of the concentration of nitrous oxide. That is, when the concentration of nitrous oxide in the exhaust gas increases and reaches the determination value lower than the emission regulation value of the concentration of nitrous oxide, the control device 18 ends the retardation of the ignition timing.

[0030] Furthermore, the correlation value correlated with the concentration of nitrous oxide in the exhaust gas is, for example, thermal efficiency (heat generation rate). When the thermal efficiency decreases and reaches a threshold value, the control device 18 terminates the retardation of the ignition timing. In this case, the threshold value of the thermal efficiency is higher than the thermal efficiency corresponding to the emission regulation value of the concentration of nitrous oxide.

[0031] When the amount of ammonia is increased to increase the load on the internal combustion engine body 11, the control device 18 retards the ignition timing if the decrease in thermal efficiency continues for a predetermined period of time. When the thermal efficiency decreases and the ignition timing is retarded, the control device 18 stops the increase in the load on the internal combustion engine body 11 due to the increase in the amount of ammonia. In other words, the load on the internal combustion engine body 11 is maintained constant. When the concentration or correlation value of nitrous oxide does not reach the judgment value, or when the load on the internal combustion engine body 11 reaches the rated load, the control device 18 stops control.

[0032] The control device 18 calculates the thermal efficiency according to the operating state of the internal combustion engine body 11. The thermal efficiency is calculated as the ratio of the shaft output of the internal combustion engine body 11 to the calorific value of the input fuel. The calorific value of the fuel uses a value according to the gas composition after fuel reforming by the reformer 16. Shaft power / (fuel flow rate x fuel heat value)

[0033] <Method for controlling an internal combustion engine> FIG. 3 is a flowchart showing a control method for an internal combustion engine.

[0034] 1 and 3, the control device 18 maintains the internal combustion engine body 11 in an idle state. At this time, the control device 18 executes switching control of the switching valve 52 based on the control map in Fig. 2, and adjusts the reforming rate of the reformer 16 so that the concentration of nitrous oxide in the exhaust gas does not exceed the emission regulation value.

[0035] In step S11, the control device 18 increases the amount of ammonia supplied to the combustion chamber 21 by increasing the opening of the throttle valve 23, and the load (output) of the internal combustion engine body 11 is increased.

[0036] In step S12, the control device 18 determines whether the decrease in thermal efficiency has continued for a predetermined time. The thermal efficiency is calculated as described above. If the control device 18 determines that the decrease in thermal efficiency has not continued for the predetermined time (No), the process returns to step S11 and the load on the internal combustion engine body 11 continues to be increased.

[0037] On the other hand, if the control device 18 determines that the decrease in thermal efficiency has continued for a predetermined time (Yes), then in step S13, the control device 18 retards the ignition timing of the spark plug 22. That is, when the load on the internal combustion engine body 11 increases, the exhaust gas temperature rises, the ammonia reforming rate by the reformer 16 increases, and the hydrogen mixing rate increases. As the hydrogen mixing rate increases, the thermal efficiency increases, but once the hydrogen mixing rate exceeds a predetermined level, the thermal efficiency decreases. Therefore, the control device 18 retards the ignition timing. At this time, the control device 18 retards the ignition timing and simultaneously stops the increase in the load on the internal combustion engine body 11 due to the increase in the amount of ammonia, thereby maintaining the load constant.

[0038] In step S14, control device 18 determines whether the correlation value correlated with the concentration of nitrous oxide in the exhaust gas has reached a predetermined judgment value. In this case, control device 18 may determine whether the concentration of nitrous oxide in the exhaust gas has increased to a predetermined judgment value. Here, if control device 18 determines that the correlation value correlated with the concentration of nitrous oxide in the exhaust gas has not reached the predetermined judgment value (No), control device 18 returns to step S13 and continues to retard the ignition timing.

[0039] On the other hand, when the control device 18 determines that the correlation value correlating with the concentration of nitrous oxide in the exhaust gas has reached a preset judgment value (Yes), in step S15 the control device 18 again increases the load on the internal combustion engine body 11. Then, in step S16, the control device 18 ends the retardation of the ignition timing. In other words, when the ignition timing of the internal combustion engine body 11 is retarded, if the correlation value correlating with the concentration of nitrous oxide in the exhaust gas reaches a preset judgment value, or if the concentration of nitrous oxide in the exhaust gas has risen to the judgment value, the retardation of the ignition timing is stopped.

[0040] In step S17, it is determined whether or not the load on the internal combustion engine body 11 has reached the rated load. If the control device 18 determines that the load on the internal combustion engine body 11 has not reached the rated load (No), the process returns to step S12 and the process is repeated. On the other hand, if the control device 18 determines that the load on the internal combustion engine body 11 has reached the rated load (Yes), the control device 18 ends the ignition timing control.

[0041] FIG. 4 is a time chart showing a control method for an internal combustion engine.

[0042] 1 and 4, the control device 18 maintains the internal combustion engine body 11 in an idle state until time t1. At this time, the control device 18 executes switching control of the switching valve 52 based on the control map in Fig. 2, and adjusts the reforming rate of the reformer 16 so that the concentration of nitrous oxide in the exhaust gas does not exceed the emission regulation value.

[0043] At time t1, the control device 18 increases the amount of ammonia supplied to the combustion chamber 21, thereby increasing the load (output) of the internal combustion engine body 11. As a result, the exhaust gas temperature increases, which increases the reforming rate of the reformer 16 and the thermal efficiency. At this time, the amount of nitrous oxide emissions decreases.

[0044] At time t2, the thermal efficiency decreases, and the amount of nitrous oxide emissions increases. Then, at time t3, when the decrease in thermal efficiency has continued for a predetermined time, the load increase on the internal combustion engine body 11 due to the increase in the amount of ammonia is stopped, and the load is maintained constant. Also, at this time, the ignition timing of the spark plug 22 is retarded. As a result, although the exhaust gas temperature rises, the rate of increase decreases, and although the reforming rate of the reformer 16 increases, the rate of increase decreases, and the thermal efficiency decreases.

[0045] At time t4, the concentration of nitrous oxide in the exhaust gas rises to a threshold value, and the thermal efficiency falls to the threshold value. At this point, the load on the internal combustion engine 11 is increased again, and the ignition timing retard is terminated. This causes the thermal efficiency to rise, and the concentration of nitrous oxide in the exhaust gas to fall.

[0046] At time t5, the thermal efficiency decreases, and the amount of nitrous oxide emissions increases. Then, at time t6, when the decrease in thermal efficiency has continued for a predetermined time, the load increase on the internal combustion engine body 11 due to the increase in the amount of ammonia is stopped, and the load is maintained constant. At this time, the ignition timing of the spark plug 22 is retarded. At time t7, the concentration of nitrous oxide in the exhaust gas increases to a judgment value, and the thermal efficiency decreases to the judgment value. At this point, the load on the internal combustion engine body 11 is increased again, and the retardation of the ignition timing is stopped. Then, the thermal efficiency increases, and the concentration of nitrous oxide in the exhaust gas decreases.

[0047] At time t8, the thermal efficiency decreases and the amount of nitrous oxide emissions increases. Then, at time t9, when the decrease in thermal efficiency has continued for a predetermined time, the load on the internal combustion engine body 11 reaches the rated load and the ignition timing control ends.

[0048] [Effects of this embodiment] A control device for an internal combustion engine according to a first aspect, in an internal combustion engine having a fuel supply path 14 that supplies ammonia as fuel to a combustion chamber 21 and a reformer 16 that reforms the ammonia into hydrogen using the heat of exhaust gas, retards the ignition timing when the thermal efficiency decreases when the amount of ammonia is increased to increase the load, and ends the retardation of the ignition timing when the concentration of nitrous oxide in the exhaust gas or a correlation value correlating to the concentration of nitrous oxide in the exhaust gas reaches a predetermined judgment value.

[0049] According to the control device for an internal combustion engine according to the first aspect, if thermal efficiency decreases when the load is increased by increasing the amount of ammonia during operation of the reformer 16, the decrease in thermal efficiency can be suppressed by retarding the ignition timing. Furthermore, when the concentration of nitrous oxide in the exhaust gas or a correlation value correlating with the concentration of nitrous oxide in the exhaust gas reaches a determination value, the retardation of the ignition timing is terminated, thereby suppressing the increase in the concentration of nitrous oxide in the exhaust gas. As a result, the generation of harmful substances when ammonia is used as fuel can be suppressed.

[0050] The control device for an internal combustion engine according to a second aspect is the control device for an internal combustion engine according to the first aspect, further, the determination value is lower than the emission regulation value of the concentration of nitrous oxide, thereby making it possible to maintain the concentration of nitrous oxide lower than the emission regulation value.

[0051] A control device for an internal combustion engine according to a third aspect is the control device for an internal combustion engine according to the first or second aspect, and further retards the ignition timing if a decrease in thermal efficiency continues for a predetermined time when the load is increased by increasing the amount of ammonia, thereby making it possible to suppress deviation in the retard timing of the ignition timing due to variations in thermal efficiency.

[0052] A control device for an internal combustion engine according to a fourth aspect is the control device for an internal combustion engine according to any one of the first to third aspects, and further, when the thermal efficiency decreases and the ignition timing is retarded, the control device stops the increase in load due to the increase in the amount of ammonia, thereby making it possible to suppress an increase in the concentration of nitrous oxide in the exhaust gas.

[0053] A control device for an internal combustion engine according to a fifth aspect is the control device for an internal combustion engine according to any one of the first to fourth aspects, and further terminates the control when the load reaches a rated load if the concentration of nitrous oxide or the correlation value does not reach the determination value, thereby making it possible to suppress an increase in the concentration of nitrous oxide in the exhaust gas.

[0054] The control device for an internal combustion engine according to a sixth aspect is the control device for an internal combustion engine according to any one of the first to fifth aspects, and further includes a control map based on the temperature of exhaust gas and the flow rate of ammonia, and controls the operation of the reformer 16 based on the control map. This makes it possible to suppress an increase in the concentration of nitrous oxide in the exhaust gas.

[0055] A control method for an internal combustion engine according to a seventh aspect, in an internal combustion engine having a fuel supply path 14 that supplies ammonia as fuel to combustion chamber 21 and a reformer 16 that reforms the ammonia into hydrogen using the heat of exhaust gas, includes the steps of increasing the load by increasing the amount of ammonia, retarding the ignition timing when thermal efficiency decreases, and ending the retard of the ignition timing when the concentration of nitrous oxide in the exhaust gas or a correlation value correlating with the concentration of nitrous oxide in the exhaust gas reaches a predetermined judgment value. This makes it possible to suppress an increase in the concentration of nitrous oxide in the exhaust gas. [Explanation of symbols]

[0056] 10 Internal combustion engine 11 Internal combustion engine body 12 Intake path 13 Exhaust route 14 Fuel supply route 15. Turbocharger 16 Reformer 17 Fuel cooler 18 Control Device 21 Combustion chamber 22 Spark plug 23 Throttle valve 31 Fuel tank 32 Fuel pump 41 Compressor 42 Turbine 43 Rotation axis 51 Bypass Route 52 Switching valve 53 Cooling path 61 Temperature Sensor 62 Concentration sensor

Claims

1. An internal combustion engine having a fuel supply path for supplying ammonia as fuel to a combustion chamber and a reformer for reforming the ammonia into hydrogen using heat of exhaust gas, When the amount of ammonia is increased to increase the load, if the thermal efficiency decreases, the ignition timing is retarded, and if the concentration of nitrous oxide in the exhaust gas or a correlation value correlating with the concentration of nitrous oxide in the exhaust gas reaches a predetermined judgment value, the retardation of the ignition timing is terminated. Control device for internal combustion engines.

2. The judgment value is a value lower than the emission regulation value of the concentration of nitrous oxide. The control device for an internal combustion engine according to claim 1.

3. When the load is increased by increasing the amount of ammonia, if the decrease in thermal efficiency continues for a predetermined period of time, the ignition timing is retarded. The control device for an internal combustion engine according to claim 1.

4. When the thermal efficiency drops and the ignition timing is retarded, the load increase caused by the increase in ammonia is stopped. The control device for an internal combustion engine according to claim 1.

5. When the concentration of nitrous oxide or the correlation value does not reach the judgment value, and the load reaches the rated load, the control is terminated. The control device for an internal combustion engine according to claim 1.

6. a control map based on the temperature of the exhaust gas and the flow rate of ammonia, and the operation of the reformer is controlled based on the control map; The control device for an internal combustion engine according to claim 1.

7. An internal combustion engine having a fuel supply path for supplying ammonia as fuel to a combustion chamber, and having a reformer for reforming the ammonia into hydrogen using heat of exhaust gas, increasing the load by increasing the amount of ammonia; retarding the ignition timing when the thermal efficiency decreases; a step of terminating retardation of the ignition timing when the concentration of nitrous oxide in the exhaust gas or a correlation value correlated with the concentration of nitrous oxide in the exhaust gas reaches a predetermined determination value; A control method for an internal combustion engine having the above construction.

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