engine

Abstract

To quicken a combustion speed.SOLUTION: An engine 100 includes a combustion chamber 108, an ammonia injection valve 112 provided in an intake flow path 200 communicated with the combustion chamber 108 or in the combustion chamber 108, a non-ammonia fuel injection valve 114 provided in the combustion chamber 108, and a control device 116 for executing two-stage injection control to allow the non-ammonia fuel injection valve 114 to perform first fuel injection in a compression stroke and to allow the non-ammonia fuel injection valve 114 to perform second fuel injection after the first fuel injection.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to engines. [Background technology]

[0002] Various proposals have been made in the past regarding engines. For example, as disclosed in Patent Document 1, a technology has been proposed that uses ammonia as engine fuel. By using ammonia as engine fuel, carbon dioxide emissions are suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-148198 Summary of the Invention [Problem to be solved by the invention]

[0004] Ammonia is flame-retardant, meaning it is more difficult to burn than other fuels. Therefore, when ammonia is used as an engine fuel, the combustion speed may be slow, which may result in low in-cylinder pressure. Therefore, it is desirable to increase the combustion speed.

[0005] An object of the present disclosure is to provide an engine capable of increasing the combustion rate. [Means for solving the problem]

[0006] In order to solve the above problems, an engine of the present disclosure includes a combustion chamber, an ammonia injector provided in an intake passage communicating with the combustion chamber or in the combustion chamber, a non-ammonia fuel injector provided in the combustion chamber, and a control device that executes two-stage injection control by causing the non-ammonia fuel injector to perform a first fuel injection during a compression stroke and causing the non-ammonia fuel injector to perform a second fuel injection after the first fuel injection, wherein the first fuel injection is performed in the first half of the compression stroke and the second fuel injection is performed in the second half of the compression stroke or the first half of the expansion stroke, the non-ammonia fuel injected in the first fuel injection is mixed with an air-fuel mixture consisting of intake air and ammonia in the combustion chamber, and the air-fuel mixture containing the non-ammonia fuel in the combustion chamber is ignited and combusted using the non-ammonia fuel injected in the second fuel injection as an ignition source. The control device executes two-stage injection control when the intake air temperature is lower than the reference temperature. .

[0009] In two-stage injection control, when it is determined that combustion in the combustion chamber is unstable, the control device may increase the injection amount of at least one of the first fuel injection and the second fuel injection compared to when it is not determined that combustion in the combustion chamber is unstable. [Effects of the Invention]

[0010] According to the present disclosure, the combustion rate can be increased. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an engine according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a flowchart showing the flow of a first processing example related to setting of the control mode of the non-ammonia fuel injector, which is performed by the control device according to the embodiment of the present disclosure. [Figure 3] FIG. 3 is a flowchart showing the flow of a second processing example related to setting of the control mode of the non-ammonia fuel injector, which is performed by the control device according to the embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram showing an example of injection timings of non-ammonia fuel and ammonia in two-stage injection control according to an embodiment of the present disclosure. [Figure 5]FIG. 5 is a diagram showing an example of a transition of the in-cylinder pressure when two-stage injection control according to the embodiment of the present disclosure is performed. [Figure 6] FIG. 6 is a flowchart showing an example of a processing flow related to setting of the injection amount of the first fuel injection in the two-stage injection control performed by the control device according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and, unless otherwise specified, do not limit the present disclosure. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0013] FIG. 1 is a schematic diagram showing the configuration of an engine 100 according to this embodiment. For ease of understanding, only one cylinder is shown in FIG. 1. However, the engine 100 may be provided with multiple cylinders. In FIG. 1, the intake port 104a, the exhaust port 104b, the ammonia injector 112, and the non-ammonia fuel injector 114 are shown on the same cross section. However, the intake port 104a, the exhaust port 104b, the ammonia injector 112, and the non-ammonia fuel injector 114 do not have to be located on the same cross section.

[0014] 1, the engine 100 includes a cylinder liner 102, a cylinder head 104, and a piston 106. The piston 106 is housed within the cylinder liner 102. The cylinder liner 102, the cylinder head 104, and the piston 106 form a combustion chamber 108.

[0015] An intake port 104a and an exhaust port 104b are formed in the cylinder head 104. The intake port 104a and the exhaust port 104b open to the combustion chamber 108. The intake valve 110a opens and closes the opening of the intake port 104a on the combustion chamber 108 side. The exhaust valve 110b opens and closes the opening of the exhaust port 104b on the combustion chamber 108 side. The opening and closing operations of the intake valve 110a and the exhaust valve 110b are performed in accordance with the rotation of a camshaft (not shown).

[0016] A pipe forming an intake flow path 200 is connected to the intake port 104a. The intake flow path 200 communicates with the combustion chamber 108 of the engine 100. Intake air, which is air supplied to the combustion chamber 108, flows through the intake flow path 200. An intake port (not shown) is provided at the upstream end of the intake flow path 200, through which air is taken in from the outside. The intake air taken into the intake flow path 200 from the intake port flows into the combustion chamber 108 via the intake port 104a. The intake port 104a corresponds to the downstream end of the intake flow path 200. The intake port 104a is included in the intake flow path 200.

[0017] A pipe forming an exhaust flow path 300 is connected to the exhaust port 104b. The exhaust flow path 300 communicates with the combustion chamber 108 of the engine 100. Exhaust gas discharged from the combustion chamber 108 flows through the exhaust flow path 300. An exhaust port (not shown) is provided at the downstream end of the exhaust flow path 300, through which the exhaust gas is discharged to the outside. Exhaust gas is discharged from the combustion chamber 108 via the exhaust port 104b. The exhaust gas discharged from the exhaust port 104b flows through the exhaust flow path 300 and is discharged from the exhaust port. The exhaust port 104b corresponds to the upstream end of the exhaust flow path 300. The exhaust port 104b is included in the exhaust flow path 300.

[0018] The ammonia injector 112 is connected to a supply source of ammonia used as fuel. The supply source of ammonia is, for example, an ammonia tank (not shown). In the example of FIG. 1, the ammonia injector 112 is provided in the intake flow path 200 upstream of the intake port 104a. The tip of the ammonia injector 112 faces the intake port 104a. However, the ammonia injector 112 may be provided in the intake port 104a. The ammonia injector 112 injects ammonia as a fuel gas into the intake port 104a. Gaseous ammonia is injected from the ammonia injector 112. In this way, the engine 100 is an engine that uses ammonia as fuel.

[0019] However, the ammonia injector 112 may be provided in the combustion chamber 108. In this case, the ammonia injector 112 is provided in the cylinder head 104 so as to face the inside of the combustion chamber 108, and injects ammonia directly into the combustion chamber 108. In this case, the ammonia injector 112 injects gaseous or liquid ammonia.

[0020] The non-ammonia fuel injector 114 is connected to a supply source of non-ammonia fuel, which is a fuel other than ammonia. For example, diesel is used as the non-ammonia fuel. In this case, the supply source of the non-ammonia fuel is, for example, a diesel tank (not shown). However, a fuel other than diesel, such as heavy oil, may also be used as the non-ammonia fuel. The non-ammonia fuel injector 114 is provided in the combustion chamber 108. In the example of FIG. 1 , the non-ammonia fuel injector 114 is provided in the cylinder head 104 so as to face the inside of the combustion chamber 108, and directly injects the non-ammonia fuel into the combustion chamber 108. For example, liquid non-ammonia fuel is injected from the non-ammonia fuel injector 114.

[0021] Ammonia is less combustible than other fuels, so in order to ensure combustibility in the combustion chamber 108, the engine 100 uses a non-ammonia fuel in addition to ammonia.

[0022] The engine 100 is a four-stroke engine. During the intake stroke, ammonia is injected from the ammonia injector 112, the intake valve 110a opens, and the exhaust valve 110b closes. The piston 106 moves toward bottom dead center, and intake air and ammonia are drawn into the combustion chamber 108 through the intake port 104a. During the compression stroke, the intake valve 110a and the exhaust valve 110b close. The piston 106 moves toward top dead center, and the air-fuel mixture in the combustion chamber 108 is compressed. When the piston 106 reaches near top dead center, non-ammonia fuel is injected from the non-ammonia fuel injector 114, which enhances combustibility in the combustion chamber 108. This ignites and burns the air-fuel mixture in the combustion chamber 108. During the expansion stroke, the piston 106 is pressed toward the bottom dead center. During the exhaust stroke, the intake valve 110a closes and the exhaust valve 110b opens. As the piston 106 approaches top dead center, the exhaust gas after combustion is discharged from the combustion chamber 108 through the exhaust port 104b.

[0023] The engine 100 switches between one-stage injection control, in which non-ammonia fuel is injected once as described above during one combustion cycle consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, and two-stage injection control, in which non-ammonia fuel is injected twice during one combustion cycle. In the two-stage injection control, non-ammonia fuel is injected not only when the piston 106 reaches near the top dead center during the compression stroke, but also at a timing before that timing. In this embodiment, by executing the two-stage injection control, the combustion speed can be increased, as will be described later.

[0024] The engine 100 includes a control device 116. The control device 116 includes a central processing unit (CPU), a ROM in which programs and the like are stored, a RAM as a work area, and the like. The control device 116 controls the operation of each device of the engine 100. For example, the control device 116 controls the operation of the ammonia injector 112 and the non-ammonia fuel injector 114.

[0025] The control device 116 also acquires information from each sensor. For example, an intake air temperature sensor 202 and an intake air pressure sensor 204 are provided in the intake air flow path 200. The intake air temperature sensor 202 detects the intake air temperature, which is the temperature of the intake air in the intake air flow path 200. Since the intake air temperature is approximately the same as the outside air temperature, for example, a sensor that detects the outside air temperature can be used as the intake air temperature sensor 202. The intake air temperature sensor 202 may be provided in the intake air flow path 200, or may be provided at a location other than the intake air flow path 200. The intake air pressure sensor 204 detects the intake air pressure, which is the pressure of the intake air in the intake air flow path 200. For example, the intake air pressure sensor 204 can be provided in an intake manifold (not shown) of the intake air flow path 200.

[0026] As described above, the control device 116 switches the control mode of the non-ammonia fuel injector 114 between one-stage injection control and two-stage injection control. In the one-stage injection control, the control device 116 causes the non-ammonia fuel injector 114 to inject fuel at the timing when the piston 106 reaches near top dead center during the compression stroke. In the two-stage injection control, the control device 116 causes the non-ammonia fuel injector 114 to inject fuel at the timing when the piston 106 reaches near top dead center during the compression stroke, as well as at a timing earlier than that timing. The first fuel injection in the two-stage injection control is called the first fuel injection, and the second fuel injection in the two-stage injection control is called the second fuel injection.

[0027] When it is determined that ignition of the fuel in the combustion chamber 108 is unlikely to occur, the control device 116 sets the control mode of the non-ammonia fuel injector 114 to two-stage injection control and executes two-stage injection control. On the other hand, when it is determined that ignition of the fuel in the combustion chamber 108 is likely to occur, the control device 116 sets the control mode of the non-ammonia fuel injector 114 to one-stage injection control and executes one-stage injection control. Hereinafter, a first processing example and a second processing example related to setting the control mode of the non-ammonia fuel injector 114 will be described with reference to Figs. 2 and 3.

[0028] 2 is a flowchart showing the flow of a first processing example regarding setting of the control mode of the non-ammonia fuel injector 114, which is performed by the control device 116 according to this embodiment. For example, the control flow shown in FIG. 2 is repeatedly executed at preset time intervals.

[0029] 2 starts, the control device 116 acquires the intake air temperature in step S101. The intake air temperature can be acquired from the intake air temperature sensor 202, for example.

[0030] Next, in step S102, the control device 116 determines whether the intake air temperature is lower than a reference temperature. Here, the lower the intake air temperature, the more difficult it is for the fuel to ignite in the combustion chamber 108. The reference temperature is set to a temperature low enough to determine that the fuel in the combustion chamber 108 is less likely to ignite. If the intake air temperature is lower than the reference temperature, the fuel in the combustion chamber 108 is less likely to ignite.

[0031] If it is determined that the intake air temperature is equal to or higher than the reference temperature (step S102 / NO), the process proceeds to step S103. In step S103, the control device 116 sets the control mode of the non-ammonia fuel injector 114 to one-stage injection control, and the control flow shown in Fig. 2 ends.

[0032] On the other hand, if it is determined that the intake air temperature is lower than the reference temperature (step S102 / YES), the process proceeds to step S104. In step S104, the control device 116 sets the control mode of the non-ammonia fuel injector 114 to two-stage injection control, and the control flow shown in Fig. 2 ends.

[0033] 3 is a flowchart showing the flow of a second processing example regarding setting of the control mode of the non-ammonia fuel injector 114, which is performed by the control device 116 according to this embodiment. For example, the control flow shown in FIG. 3 is repeatedly executed at preset time intervals.

[0034] The second processing example in FIG. 3 differs from the first processing example in FIG. 2 described above in that steps S101 and S102 are replaced with steps S201 and S202.

[0035] 3 is started, in step S201, the control device 116 acquires an ammonia equivalence ratio. The ammonia equivalence ratio is the ratio of the amount of ammonia supplied to the amount of air supplied to the combustion chamber 108 of the engine 100. The control device 116 can estimate the amount of air supplied to the combustion chamber 108 based on, for example, the detection result of the intake pressure sensor 204. Therefore, the control device 116 can calculate the ammonia equivalence ratio based on the estimation result of the amount of air supplied to the combustion chamber 108 and the amount of ammonia injected by the ammonia injector 112. Note that the control device 116 determines the amount of ammonia injection based on, for example, the output of the engine 100. The amount of ammonia injection determined in this manner can be used to calculate the ammonia equivalence ratio.

[0036] Next, in step S202, the control device 116 determines whether the ammonia equivalence ratio is lower than a reference equivalence ratio. Here, the lower the ammonia equivalence ratio, the more difficult it is for the fuel to ignite in the combustion chamber 108. The reference equivalence ratio is set to an equivalence ratio that is low enough to determine that the fuel is less likely to ignite in the combustion chamber 108. When the ammonia equivalence ratio is lower than the reference equivalence ratio, the fuel is less likely to ignite in the combustion chamber 108.

[0037] If it is determined that the ammonia equivalence ratio is equal to or greater than the reference equivalence ratio (step S202 / NO), the process proceeds to step S103. In step S103, the control device 116 sets the control mode of the non-ammonia fuel injector 114 to one-stage injection control, and the control flow shown in Fig. 3 ends.

[0038] On the other hand, if it is determined that the ammonia equivalence ratio is lower than the reference equivalence ratio (step S202 / YES), the process proceeds to step S104. In step S104, the control device 116 sets the control mode of the non-ammonia fuel injector 114 to two-stage injection control, and the control flow shown in Fig. 3 ends.

[0039] Fig. 4 is a diagram showing an example of the injection timing of non-ammonia fuel and ammonia in two-stage injection control according to this embodiment. In Fig. 4, the period of each stroke in one fuel cycle is shown by the crank angle. In the example of Fig. 4, the period of the intake stroke is the period from approximately 0° to 180° in crank angle. The period of the compression stroke is the period from approximately 180° to 360° in crank angle. The period of the expansion stroke is the period from approximately 360° to 540° in crank angle. The period of the exhaust stroke is the period from approximately 540° to 720° in crank angle.

[0040] A period T1 in Fig. 4 is a period during which ammonia is injected by the ammonia injector 112. As shown in Fig. 4, the control device 116 causes the ammonia injector 112 to inject ammonia during the intake stroke. Note that the period T1 is common to, for example, the cases where the control mode of the non-ammonia fuel injector 114 is one-stage injection control and two-stage injection control.

[0041] Period T2 in Fig. 4 is a period during which the first fuel injection is performed by non-ammonia fuel injector 114. As shown in Fig. 4, control device 116 causes non-ammonia fuel injector 114 to perform the first fuel injection during the compression stroke. Period T2 is, for example, a period included in the first half of the compression stroke. For example, period T2 is a period included in the period from approximately 180° to 270° in crank angle.

[0042] Period T3 in Fig. 4 is the period during which the second fuel injection is performed by the non-ammonia fuel injector 114. As shown in Fig. 4, the control device 116 causes the non-ammonia fuel injector 114 to perform the second fuel injection after the first fuel injection. Period T3 is, for example, the timing when the piston 106 reaches near top dead center during the compression stroke.

[0043] The control device 116 determines a target value of the total injection amount of non-ammonia fuel in one combustion cycle based on, for example, the output of the engine 100. Then, the control device 116 determines the injection amount of the first fuel injection and the injection amount of the second fuel injection so that the sum of the injection amount of the first fuel injection and the injection amount of the second fuel injection matches the target value of the total injection amount. Here, the ratio between the injection amount of the first fuel injection and the injection amount of the second fuel injection can be set appropriately. For example, the ratio between the injection amount of the first fuel injection and the injection amount of the second fuel injection may be 1:1.

[0044] As described above, in this embodiment, the control device 116 executes two-stage injection control by causing the non-ammonia fuel injector 114 to perform the first fuel injection during the compression stroke, and then causing the non-ammonia fuel injector 114 to perform the second fuel injection after the first fuel injection. As a result, the first fuel injection is performed during the compression stroke, and non-ammonia fuel is further mixed into the air-fuel mixture consisting of intake air and ammonia in the combustion chamber 108. Then, the air-fuel mixture in the combustion chamber 108 is ignited and burned using the non-ammonia fuel injected in the second fuel injection as an ignition source. In this way, by ensuring that the air-fuel mixture in the combustion chamber 108 that is ignited contains non-ammonia fuel, the combustibility of the mixture can be improved and the time required for flame propagation can be shortened. Therefore, the combustion speed can be increased.

[0045] Fig. 5 is a diagram showing an example of the transition of the in-cylinder pressure when two-stage injection control according to this embodiment is performed. In Fig. 5, similar to Fig. 4, the period of each stroke in one fuel cycle is indicated by the crank angle. Note that the dashed line in Fig. 5 shows an example of the transition of the in-cylinder pressure when one-stage injection control is performed.

[0046] As described above, when two-stage injection control is performed, the non-ammonia fuel injected in the second fuel injection serves as an ignition source to ignite and burn the air-fuel mixture in the combustion chamber 108. Therefore, as shown by the solid line in FIG. 5, the in-cylinder pressure begins to rise near the end of the compression stroke. The in-cylinder pressure then peaks immediately after the start of the expansion stroke. Here, when single-stage injection control is performed in a situation where fuel ignition in the combustion chamber 108 is unlikely to occur, the in-cylinder pressure generally rises and falls more gradually as shown by the dashed line in FIG. 5 compared to when two-stage injection control is performed. The peak in-cylinder pressure is lower compared to when two-stage injection control is performed.

[0047] As shown by the dashed line in Fig. 5, in a situation where ignition of fuel in the combustion chamber 108 is difficult, if the air-fuel mixture in the combustion chamber 108 that is ignited does not contain non-ammonia fuel, the combustion speed will be slowed down and the in-cylinder pressure will be low. On the other hand, according to this embodiment, the combustion speed can be increased by performing two-stage injection control, and therefore the in-cylinder pressure will increase as shown by the solid line in Fig. 5.

[0048] In the first processing example of FIG. 2 described above, the control device 116 executes two-stage injection control when the intake air temperature is lower than a reference temperature. In the second processing example of FIG. 3 described above, the control device 116 executes two-stage injection control when the ammonia equivalence ratio is lower than a reference equivalence ratio. In both the first processing example and the second processing example, when it is determined that the fuel in the combustion chamber 108 is unlikely to ignite, two-stage injection control is executed, thereby making it possible to increase the combustion speed. On the other hand, when it is determined that the fuel in the combustion chamber 108 is likely to ignite, one-stage injection control is executed, thereby preventing the injection amount of non-ammonia fuel from becoming unnecessarily large. This makes it possible to reduce carbon dioxide emissions.

[0049] The control device 116 may use both the intake air temperature being lower than a reference temperature and the ammonia equivalence ratio being lower than a reference equivalence ratio as conditions for executing the two-stage injection control. For example, the control device 116 may execute the two-stage injection control when the intake air temperature is lower than a reference temperature and the ammonia equivalence ratio is lower than the reference equivalence ratio. For example, the control device 116 may execute the two-stage injection control when either the intake air temperature being lower than the reference temperature or the ammonia equivalence ratio being lower than the reference equivalence ratio is satisfied.

[0050] In the above, an example in which the second fuel injection is performed during the compression stroke in two-stage injection control has been described with reference to Fig. 4. However, the second fuel injection may be performed during the expansion stroke. For example, the second fuel injection may be performed immediately after the piston 106 reaches top dead center during the expansion stroke.

[0051] An example of the period T2 during which the first fuel injection is performed has been described above with reference to Fig. 4. Here, the period T2 during which the first fuel injection is performed preferably starts with a time interval from the timing when the piston 106 reaches bottom dead center. This prevents the non-ammonia fuel injected by the first fuel injection from adhering to the cylinder liner 102 and causing excessively early ignition in the combustion chamber 108. Note that the control device 116 may change the timing of the first fuel injection based on various parameters such as the output of the engine 100, the intake air temperature, or the intake air pressure.

[0052] Here, the control device 116 may perform processing to adjust the injection amount of at least one of the first fuel injection and the second fuel injection in the two-stage injection control in order to further optimize the combustion speed in the combustion chamber 108. An example of such processing will be described below with reference to FIG.

[0053] Fig. 6 is a flowchart showing an example of the flow of processing related to setting the injection amount of the first fuel injection in the two-stage injection control performed by the control device 116 according to this embodiment. For example, the control flow shown in Fig. 6 is executed in parallel or sequentially with the control flow shown in Fig. 2 or the control flow shown in Fig. 3 described above. For example, the control flow shown in Fig. 6 is repeatedly executed at preset time intervals.

[0054] 6 starts, in step S301, the control device 116 determines whether combustion in the combustion chamber 108 is unstable. For example, the control device 116 may determine that combustion in the combustion chamber 108 is unstable when the rotation speed or output of the engine 100 fluctuates excessively greatly. For example, the control device 116 may determine that combustion in the combustion chamber 108 is unstable when the intake air temperature is excessively low. In this way, the control device 116 can determine whether combustion in the combustion chamber 108 is unstable based on the operating state of the engine 100, such as the rotation speed or output of the engine 100, or the intake air temperature.

[0055] When it is not determined that the combustion in the combustion chamber 108 is unstable (step S301 / NO), the process proceeds to step S302. In step S302, the control device 116 sets the injection amount of the first fuel injection to the first amount, and the control flow shown in FIG. 6 ends.

[0056] On the other hand, if it is determined that the combustion in the combustion chamber 108 is unstable (step S301 / YES), the process proceeds to step S303. In step S303, the control device 116 sets the injection amount of the first fuel injection to the second amount, and the control flow shown in FIG. 6 ends.

[0057] The second amount is greater than the first amount. For example, if the injection amount of the second fuel injection is constant regardless of the injection amount of the first fuel injection, the total injection amount of the non-ammonia fuel when the injection amount of the first fuel injection is set to the second amount is greater than the total injection amount of the non-ammonia fuel when the injection amount of the first fuel injection is set to the first amount.

[0058] 6, in the two-stage injection control, when it is determined that combustion in the combustion chamber 108 is unstable, the control device 116 increases the injection amount of the first fuel injection compared to when it is not determined that combustion in the combustion chamber 108 is unstable. As a result, when it is determined that combustion in the combustion chamber 108 is unstable, the amount of non-ammonia fuel contained in the ignited air-fuel mixture in the combustion chamber 108 increases. Therefore, in such a case, it is possible to further improve the combustibility of the air-fuel mixture and more appropriately increase the combustion speed.

[0059] In the above, an example has been described in which, in the two-stage injection control, when it is determined that combustion in the combustion chamber 108 is unstable, the injection amount of the first fuel injection is larger than when it is not determined that combustion in the combustion chamber 108 is unstable. However, in the two-stage injection control, when it is determined that combustion in the combustion chamber 108 is unstable, the control device 116 may increase the injection amount of the second fuel injection instead of the injection amount of the first fuel injection, or may increase both the first fuel injection and the second fuel injection, compared to when it is not determined that combustion in the combustion chamber 108 is unstable. In other words, in the two-stage injection control, when it is determined that combustion in the combustion chamber 108 is unstable, the control device 116 may increase at least one of the first fuel injection and the second fuel injection, compared to when it is not determined that combustion in the combustion chamber 108 is unstable. As a result, when it is determined that combustion in the combustion chamber 108 is unstable, the amount of non-ammonia fuel supplied into the combustion chamber 108 is increased. This further improves the combustibility of the air-fuel mixture and more appropriately increases the combustion speed.

[0060] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present disclosure.

[0061] This disclosure can contribute, for example, to Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Ensure access to affordable, reliable, sustainable and modern energy." [Explanation of symbols]

[0062] 100 Engine 108 Combustion chamber 112 Ammonia injector 114 Non-ammonia fuel injector 116 Control device 200 Intake passage

Claims

1. A combustion chamber; an ammonia injector provided in an intake passage communicating with the combustion chamber or in the combustion chamber; a non-ammonia fuel injection valve provided in the combustion chamber; a control device that executes two-stage injection control by causing the non-ammonia fuel injector to perform a first fuel injection during a compression stroke and causing the non-ammonia fuel injector to perform a second fuel injection after the first fuel injection; Equipped with The first fuel injection is performed in the first half of the compression stroke, The second fuel injection is performed in the latter half of the compression stroke or the first half of the expansion stroke, the non-ammonia fuel injected in the first fuel injection is mixed with a mixture of intake air and ammonia in the combustion chamber, the non-ammonia fuel injected in the second fuel injection is used as an ignition source to ignite and burn the air-fuel mixture containing the non-ammonia fuel in the combustion chamber, the control device executes the two-stage injection control when the intake air temperature is lower than a reference temperature. engine.

2. When it is determined that combustion in the combustion chamber is unstable, the control device increases the injection amount of at least one of the first fuel injection and the second fuel injection compared to when it is not determined that combustion in the combustion chamber is unstable in the two-stage injection control.

10. The engine of claim 1.

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