Engine control device, engine control method, and storage medium

Abstract

Provided is an engine control device, an engine control method, and a storage medium. An intake valve is closed after a compression stroke is started. One of a predetermined period before the compression stroke is started and a predetermined period after the intake valve is closed is a first injection period, and the other is a second injection period. A premature ignition prevention injection process is performed in which, in a case where a period required for fuel injection of a required injection amount is longer than the first injection period, an injector is controlled in a manner in which the fuel of the required injection amount is injected so as to be distributed to the first injection period and the second injection period.

Description

Technical Field

[0001] This disclosure relates to engine control devices, engine control methods, and storage media. Background Technology

[0002] In automotive engines, when cylinder temperatures rise due to conditions such as high load operation, spark plugs or other components may become overheated, leading to premature ignition. Premature ignition refers to the phenomenon where the fuel-air mixture ignites itself before it can be ignited by the spark plug, for example, due to localized high temperatures inside the cylinder. It is a type of abnormal combustion.

[0003] The engine control device described in Japanese Patent Application Publication No. 2016-130473, when detecting premature ignition, accelerates the combustion rate by increasing the fuel injection quantity or advancing the ignition timing, thereby suppressing premature ignition. Summary of the Invention

[0004] Technical solutions for solving the problem

[0005] According to one aspect of this disclosure, an engine control device is provided, comprising a control circuit. The control circuit controls an engine. The engine includes an injector for injecting fuel into cylinders. The intake valve closes after the start of the compression stroke. Here, one of a predetermined period before the start of the compression stroke and the other of a predetermined period after the intake valve closes are respectively defined as a first injection period and a second injection period. The control circuit of the aforementioned engine control device is configured to perform a process to prevent premature ignition injection. In the case where the period required for injecting the required amount of fuel is longer than the first injection period, the injector is controlled to inject the required amount of fuel in a distributed manner to both the first and second injection periods.

[0006] The upper part of the engine cylinder contains components such as exhaust valves and spark plugs, which are prone to becoming hot spots during engine operation. On the other hand, during the compression stroke, the piston rises within the cylinder, pushing the intake air upwards. If the intake valve opens at this time, the intake air escapes towards the intake port, creating an upward airflow within the cylinder. If fuel is injected from the injector during this airflow, the fuel spray rides this airflow upwards. If the exhaust valves and spark plugs become hot at this point, the fuel spray will come into contact with these hot components and ignite, potentially causing premature ignition. That is, in an engine where the intake valves are closed after the start of the compression stroke, if the fuel spray is injected from the start of the compression stroke (e.g., during the compression stroke), the fuel spray will ignite upwards. Figure 3 T2) to intake valve closing (e.g. Figure 3 If fuel is injected into the cylinder during the IVC (Injection of Fuel) period, premature ignition is likely to occur.

[0007] The aforementioned pre-premature ignition injection treatment controls the injector in cases where the required amount of fuel cannot be fully injected during the first injection period. This is achieved by distributing the required fuel amount across the first and second injection periods. In other words, the pre-premature ignition injection treatment avoids injection from the start of the compression stroke (e.g., ...). Figure 3 T2) to intake valve closing (e.g. Figure 3 Fuel injection is performed during the period up to the IVC (Injection Channel) when premature ignition is likely to occur. Therefore, premature ignition is less likely to occur.

[0008] The engine's fuel injection quantity and ignition timing are typically controlled to optimal values ​​for fuel efficiency and exhaust performance. Therefore, increasing the fuel injection quantity or advancing the ignition timing will deteriorate the engine's fuel efficiency and exhaust performance. The above-mentioned configuration can suppress such deterioration.

[0009] Furthermore, the control circuit can also be configured such that, when the period required for injecting the required amount of fuel is shorter than the first injection period, the injector is controlled to inject the required amount of fuel during the first injection period. If the pre-ignition injection process is configured in this way, fuel injection will also avoid periods during which pre-ignition is likely to occur if fuel is injected, even when the period required for injecting the required amount of fuel is shorter than the first injection period.

[0010] Furthermore, depending on the engine's operating state, there are situations where premature ignition is unlikely to occur even if fuel is injected during the period from the start of the compression stroke to the closing of the intake valve. Therefore, the control circuit of the engine control unit can be configured to perform a determination process to determine whether the engine is in a state prone to premature ignition. The control circuit can only perform the aforementioned premature ignition prevention injection process if the determination process determines that the engine is in a state prone to premature ignition. Additionally, when the engine torque is high and the engine coolant temperature is high, the temperature inside the cylinder increases, making premature ignition more likely. Therefore, the control circuit can be configured to determine whether the engine is in a state prone to premature ignition based on engine torque and engine coolant temperature. On the other hand, even if fuel is injected during the period from the start of the compression stroke to the closing of the intake valve, if the fuel injection pressure is high enough, the atomized fuel spray may not easily ride the airflow inside the cylinder. In this case, premature ignition is unlikely to occur. Therefore, the control circuit can be configured to determine whether the engine is in a state prone to premature ignition based on the fuel injection pressure of the injector.

[0011] Furthermore, the aforementioned engine control device can be configured to set a predetermined period after the intake valve closes as the first injection period.

[0012] According to another aspect of this disclosure, an engine control method is provided that performs the same processing as the processes of the engine control device described above.

[0013] According to another aspect of this disclosure, a storage medium is provided, which is a non-transitory computer-readable storage medium, storing control processing that causes the processing device to perform the same processing as the processing of the aforementioned engine control device. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the configuration of one embodiment of the engine control device of this disclosure.

[0015] Figure 2 yes Figure 1 The flowchart shown is of the fuel injection control routine executed by the engine control unit.

[0016] Figure 3 middle, Figure 3 Part (A) is shown Figure 1 The diagram shows the timing of the intake valve's opening and closing states. Figure 3 Part (B) is a timing diagram showing the implementation of fuel injection when the required injection period is less than or equal to the length of the first injection period. Figure 3 Part (C) is a timing diagram showing the implementation of fuel injection when the engine is not operating in the premature ignition operating region and the required injection period is longer than the first injection period. Figure 3 Part (D) is a timing diagram showing the implementation of fuel injection when the engine is operating in the premature ignition operating region and the required injection period is longer than the first injection period. Detailed Implementation

[0017] The following is for reference Figures 1-3 This document provides a detailed description of one embodiment of the engine control device, engine control method, and engine control processing.

[0018] <Composition of Engine Control Unit>

[0019] First, refer to Figure 1 The configuration of the engine control device in this embodiment will be explained. The engine 10, which is controlled by the engine control device of this embodiment, is mounted in a vehicle. Furthermore, the engine 10 is configured as a hydrogen engine that uses hydrogen as fuel.

[0020] The engine 10 has a cylinder 11. Inside the cylinder 11, a piston 12 is arranged to reciprocate freely in the vertical direction shown in the figure. Furthermore, the piston 12 divides the cylinder 11 into a combustion chamber 13 for combustion. An intake port 15 is connected to the upper part of the cylinder 11 via an intake valve 14. Additionally, an exhaust port 17 is connected to the upper part of the cylinder 11 via an exhaust valve 16. Moreover, an injector 18 for injecting hydrogen into the cylinder 11 and a spark plug 19 for igniting the hydrogen injected by the injector 18 are provided at the upper part of the cylinder 11. Furthermore, the closing timing of the intake valve 14 in this engine 10 (e.g., ...) is... Figure 3 The IVC setting is at the start of the compression stroke (e.g.) Figure 3 After T2).

[0021] The electronic control unit 20 that controls the engine 10 is a control circuit equipped with a processing unit 21 and a storage unit 22. The storage unit 22 stores the programs and data used in the control process. The storage unit 22 is an example of a non-transitory, computer-readable storage medium. The processing unit 21 is a processing unit that performs various processes related to the control of the engine 10 by executing programs read from the storage unit 22. In this embodiment, such an electronic control unit 20 corresponds to an engine control unit.

[0022] The electronic control unit 20 is connected to a crankshaft angle sensor 23, an air flow meter 24, a coolant temperature sensor 25, an accelerator pedal sensor 26, and a fuel pressure sensor 27. The crankshaft angle sensor 23 detects the rotational phase of the crankshaft of the engine 10. The air flow meter 24 detects the amount of air intake into the engine 10. The coolant temperature sensor 25 detects the temperature of the coolant in the engine 10, i.e., the engine coolant temperature THW. The accelerator pedal sensor 26 detects the amount of accelerator pedal operation (ACC) by the driver. The fuel pressure sensor 27 detects the pressure of the fuel supplied to the injector 18. Based on the detection result from the crankshaft angle sensor 23, the electronic control unit 20 calculates the engine speed NE of the engine 10. Furthermore, based on the intake air volume detected by the air flow meter 24 and the engine speed NE, the electronic control unit 20 calculates the engine load rate KL. The engine load rate KL represents the intake air filling rate of the combustion chamber 13. The electronic control unit 20 also calculates the fuel injection pressure PF of the injector 18 based on the detection results of the fuel pressure sensor 27, etc. In addition, the electronic control unit 20 is also connected to various sensors installed in various parts of the vehicle.

[0023] <Fuel Injection Control>

[0024] The electronic control unit 20 performs fuel injection control of the injector 18 as part of the engine control. Details of the fuel injection control are explained below.

[0025] Figure 2 The diagram shows a flowchart of the fuel injection control routine executed by the electronic control unit 20 for fuel injection control. During engine 10 operation, the electronic control unit 20 repeatedly executes this routine at predetermined control cycles. Furthermore, Figure 2 The timing values ​​shown represent the advance of the crankshaft angle from top dead center of the compressor. Therefore, a larger timing value is considered an earlier timing value compared to a smaller one. Additionally, Figure 2 and Figure 3 The values ​​shown for each period represent the amount of crankshaft rotation during that period.

[0026] Upon starting this routine, the electronic control unit 20 first calculates the required injection quantity QS in step S100, based on engine speed NE and accelerator pedal operation amount ACC, etc. The required injection quantity QS is the required value of hydrogen injection quantity from the injector 18.

[0027] Next, in step S110, the electronic control unit 20 calculates the required injection period TS based on the required injection quantity QS, engine speed NE, and injection pressure PF. The required injection period TS represents the value obtained by converting the time required to inject hydrogen at the required injection quantity QS into the crankshaft rotation angle during that time at the current engine speed NE. The crankshaft angle represents the rotation angle of the output shaft of the engine 10, i.e., the crankshaft. Furthermore, the higher the injection pressure PF, the greater the hydrogen injection rate of the injector 18, i.e., the greater the amount of hydrogen injected per unit time. Therefore, the lower the injection pressure PF, the longer the required injection period TS is when the required injection quantity QS and engine speed NE are constant. Additionally, the higher the engine speed NE, the greater the crankshaft rotation angle per unit time. Therefore, the higher the engine speed NE, the shorter the required injection period TS is when the required injection quantity QS and injection pressure PF are constant.

[0028] Next, in step S120, the electronic control unit 20 determines whether the engine 10 is operating in the pre-ignition operating region. The pre-ignition operating region refers to the operating region of the engine 10 where pre-ignition is prone to occur. Pre-ignition is prone to occur when the spark plug 19 and exhaust valve 16 are at high temperatures. When the engine torque TE is high, more fuel is burned in the cylinder 11 compared to when the engine torque TE is low. Therefore, when the engine torque TE is high, pre-ignition is more likely to occur compared to when the engine torque TE is low. Furthermore, when the temperature of the spark plug 19 and exhaust valve 16 increases, the engine coolant temperature THW also increases. Therefore, when the engine coolant temperature THW is high, pre-ignition is more likely to occur compared to when the engine coolant temperature THW is low. On the other hand, as will be described later, when the injection pressure PF is low, pre-ignition is more likely to occur compared to when the injection pressure PF is high. Therefore, in this embodiment, the determination of whether the engine 10 is operating in the pre-ignition operating region is based on the engine torque TE, engine coolant temperature THW, and injection pressure PF.

[0029] If the engine 10 is not operating in the premature ignition operating range (S130: No), the electronic control unit 20 advances the process to step S140. Then, in step S140, the electronic control unit 20 sets the timing of the injection stop margin TM to the value of the first injection end timing IE1 (EI1←T1+TM) that is earlier than the final injection end timing T1. Additionally, in step S140, the electronic control unit 20 sets the timing of the required injection period TS to the value of the first injection start timing IS1 (SI1←EI1+TS) that is earlier than the first injection end timing IE1. Then, in step S150, the electronic control unit 20 instructs the injector 18 to perform a single-stage injection of hydrogen from the first injection start timing IS1 to the first injection end timing IE1, and then ends the processing of this routine in this control cycle.

[0030] Furthermore, the final injection end timing T1 is the end timing of the period during which hydrogen injection is permitted. In this embodiment, the timing when the piston 12 is at top dead center of the compression stroke is set as the final injection end timing T1. Additionally, there is a delay from the injection stop instruction from the electronic control unit 20 until the injector 18 actually stops injecting hydrogen. The injection stop margin TM represents a value obtained by converting this injection stop delay time into the crankshaft rotation angle during the delay time at the current engine speed NE. The electronic control unit 20 calculates the value of this injection stop margin TM based on the engine speed NE.

[0031] In contrast, if the engine 10 is operating in the premature ignition range (S130: Yes), the electronic control unit 20 proceeds to step S160. In step S160, the electronic control unit 20 calculates the first injection period TT. Here, the period from the closing timing IVC of the intake valve 14 to the final injection end timing T1 is set as T0. The first injection period TT is expressed in crankshaft angles and is obtained by subtracting the injection stop margin TM from the period T0. This first injection period TT represents the period during which fuel injection can occur after the intake valve 14 is closed. Then, in the subsequent step S170, the electronic control unit 20 determines whether the required injection period TS is longer than the first injection period TT. If the required injection period TS is less than or equal to the first injection period TT (S170: No), the electronic control unit 20 proceeds to step S140. In contrast, if the required injection period TS is longer than the first injection period TT (S170: Yes), the electronic control unit 20 proceeds to step S180.

[0032] When the process proceeds to step S180, the electronic control unit 20 sets the timing of the injection stop margin TM to the value of the first injection end timing IE1 (IE1←T1+TM) earlier than the final injection end timing T1. Additionally, in step S180, the electronic control unit 20 sets the closing timing IVC of the intake valve 14 to the value of the first injection start timing IS1 (IS1←IVC). Furthermore, in step S180, the electronic control unit 20 sets the timing of the injection stop margin TM to the value of the second injection end timing IE2 (IE2←T2+TM) earlier than the start timing T2 of the compression stroke. Moreover, in step S180, the electronic control unit 20 sets the timing of the second injection start timing IS2 (IS2←IE2+TS-TT) earlier than the second injection end timing IE2 by the difference between the required injection period TS and the first injection period TT (=TS-TT). Then, in subsequent step S190, the electronic control unit 20 instructs the injector 18 to perform segmented injection, dividing the required injection period TS into two periods. Specifically, the required injection period TS is divided into a period from the start timing IS2 of the second injection to the end timing IE2 of the second injection, and a period from the start timing IS1 of the first injection to the end timing IE1 of the first injection, for a total of two periods. Following this instruction, the electronic control unit 20 terminates the processing of this routine in the current control cycle.

[0033] Furthermore, in this embodiment, the processing of steps S140 to S190 in such a fuel injection control routine corresponds to the processing of preventing premature ignition injection. Additionally, the processing of steps S120 to S130 corresponds to the determination processing of whether a state prone to premature ignition exists.

[0034] <Effects of the Implementation Method>

[0035] The operation and effects of this embodiment will be explained. In the following description, the period during which fuel injection can be performed after the closing timing IVC of the intake valve 14 will be designated as the "first injection period". In addition, the period during which fuel injection can be performed before the start timing T2 of the compression stroke will be designated as the "second injection period". Furthermore, in this embodiment, when describing the length of the first injection period, it will be designated as the "first injection period TT".

[0036] exist Figure 3 Part (A) shows the shift in the opening and closing state of the intake valve 14 in the engine 10. Furthermore, Figure 3 The value on the horizontal axis represents the advance of the crankshaft angle relative to the end timing (T1) of the compression stroke [°BTDC] (Before Top Dead Center). Furthermore, here, the period from the piston 12 being at bottom dead center of the intake maneuver to the piston being at top dead center of the compression maneuver is defined as the compression stroke. For example... Figure 3 As shown in section (A), the closing timing IVC of the intake valve 14 of the engine 10 is set later than the start timing T2 of the compression stroke. That is, in the engine 10, there is a period when the intake valve 14 is open after the start of the compression stroke (T2). If the intake valve 14 is open during the compression stroke when the piston 12 rises in the cylinder 11, the intake air pushed by the piston 12 in the cylinder 11 will escape towards the intake port 15, thus generating an upward airflow in the cylinder 11.

[0037] On the other hand, when the engine 10 is operating under high load, the spark plug 19, exhaust valve 16, etc., become very hot, forming a superheated spot at the top of the cylinder 11 that can become a spark. If hydrogen is injected by the injector 18 during the compression stroke when the intake valve 14 is open, the spray will travel with the airflow towards the top of the cylinder 11. Furthermore, there is a possibility that the spray will come into contact with the superheated spot formed at the top of the cylinder 11, resulting in premature ignition. Therefore, if hydrogen is injected during the compression stroke when the intake valve 14 is open, premature ignition is likely to occur. In the following description, the period from the start timing T2 of the compression stroke to the closing timing IVC of the intake valve 14 will be referred to as the premature ignition injection period. Figure 3 The premature ignition injection period is shown by the shading.

[0038] exist Figure 2In step S170 of the fuel injection control routine, the electronic control unit 20 determines whether the required injection period TS is longer than the first injection period TT. The required injection period TS represents the period required for fuel injection of the required injection quantity QS at the current engine speed NE and injection pressure PF. That is, in this step S170, it is determined whether the period required for fuel injection of the required injection quantity QS is longer than the first injection period TT. If the required injection period TS is longer than the first injection period TT, the required injection quantity QS of hydrogen cannot be completely injected within the first injection period TT. In this case, if the required injection quantity QS of hydrogen is to be injected in one go, that is, if the required injection quantity QS of hydrogen is to be injected through single-stage injection, hydrogen injection will be performed during the premature ignition injection period.

[0039] Furthermore, when the engine torque (TE) and engine coolant temperature (THW) are low, the spark plug 19 and exhaust valve 16 will not reach the high temperatures required for spray ignition. Therefore, under such conditions, even if hydrogen is injected during pre-ignition injection, pre-ignition is unlikely to occur. Additionally, the higher the injection pressure (PF) of the injector 18, the greater the spray's movement. Therefore, when the injection pressure (PF) is above a certain level, the change in the spray's direction caused by the airflow within cylinder 11 decreases, making pre-ignition difficult to occur even when hydrogen is injected during pre-ignition injection.

[0040] exist Figure 2 In step S120, the electronic control unit 20 determines whether the engine 10 is operating in the pre-ignition operating region based on engine torque TE, engine coolant temperature THW, and injection pressure PF. As described above, the pre-ignition operating region refers to the operating region of the engine 10 where pre-ignition is prone to occur. Therefore, in this step S120, a determination process is performed to determine whether the engine is in a state prone to pre-ignition based on engine torque TE, engine coolant temperature THW, and injection pressure PF.

[0041] exist Figure 2 In the fuel injection control routine, if the electronic control unit 20 determines in step S120 that the engine 10 is operating in the premature ignition zone (S130: Yes), it performs the determination in step S170. Then, if the required injection period TS is shorter than or the same as the first injection period TT (S170: No), the electronic control unit 20 performs the processing in steps S140 and S150. In this case, hydrogen injection is performed by single-stage injection, and the single-stage injection ends at the end timing IE1 of the first injection.

[0042] exist Figure 3Section (B) illustrates an example of the implementation of fuel injection in this case. In this case, the required injection period TS is shorter than the first injection period TT, so hydrogen injection of the required injection quantity QS is performed within the first injection period TT. Therefore, in this case, hydrogen injection is not performed during the premature ignition injection period.

[0043] On the other hand, if the electronic control unit 20 determines in step S170 that the required injection period TS is longer than the first injection period TT, it performs the processing in steps S180 and S190. In this case, hydrogen is injected in a segmented manner, where hydrogen injection is performed from the beginning of the first injection period after the intake valve 14 is opened, and the amount of hydrogen that is insufficient for the injection period (the amount that is not completely injected) is injected in the second injection period before the start of the compression stroke.

[0044] exist Figure 3 Section (D) illustrates an example of the implementation of fuel injection in this case. In this case, the injection of hydrogen at a required injection quantity QS is performed in a split before and after the premature ignition injection. Therefore, hydrogen injection during the premature ignition injection is not performed in this case.

[0045] Furthermore, if the electronic control unit 20 determines in step S120 that it is not in a state prone to premature ignition (S130: No), it performs hydrogen injection through the processes of steps S140 and S150. In this case, regardless of whether the required injection period TS is longer than the first injection period TT, the required injection quantity QS is injected by single-stage injection.

[0046] exist Figure 3 Section (C) illustrates an example of fuel injection implementation in this situation. Furthermore, Figure 3 The example in section (C) is a case where the required injection period TS is longer than the first injection period TT. In this case, hydrogen injection is performed in a single stage regardless of whether the required injection period TS is longer than the first injection period TT. Therefore, in this case, there is a possibility that hydrogen injection also occurs during the premature ignition injection period. However, in this case, premature ignition is unlikely to occur even if hydrogen is injected during the premature ignition injection period.

[0047] The engine control device according to the above embodiment can achieve the following effects.

[0048] (1) In this embodiment, the injection control of the injector 18 is performed to prevent premature ignition injection (S140-S190) in the following manner. That is, when the period (TS) required for the injection of fuel with a required injection quantity QS is shorter than the first injection period TT (S170: No), the injection control prevents premature ignition injection so that the fuel with a required injection quantity QS is injected during the first injection period (S140-S150). In addition, when the period required for the injection of fuel with a required injection quantity QS is longer than the first injection period TT (S170: Yes), the injection control prevents premature ignition injection so that the fuel with a required injection quantity QS is injected in a distributed manner during the first and second injection periods (S180-S190). As a result, hydrogen injection is no longer performed during the premature ignition injection period, which is prone to premature ignition. Therefore, the engine control device of this embodiment has the effect of suppressing the occurrence of premature ignition.

[0049] (2) This embodiment determines whether the state is prone to premature ignition (S120-S130). Furthermore, the above-described premature ignition prevention injection process is implemented only if the state is determined to be prone to premature ignition (S130: Yes). That is, if the state is not prone to premature ignition (S130: No), hydrogen injection during premature ignition injection is permitted. Therefore, even if the required injection period TS is longer than the first injection period TT, single-stage injection is performed instead of segmented injection when the state is not prone to premature ignition (S130: No). The drive current of the injector 18 increases at the start of injection. Therefore, by not performing segmented injection, the power consumption for driving the injector 18 can be suppressed. Additionally, the fluctuation of the hydrogen injection rate of the injector 18 increases during the period immediately following the start of injection and the period just before the end of injection. Therefore, by reducing the number of injections by not performing segmented injection, the accuracy of the hydrogen injection quantity can be improved. Furthermore, "reducing the number of sprays by not performing segmented sprays" can also suppress the wear of the nozzle blades caused by the nozzle settling at the end of the spray of the injector 18.

[0050] (3) This embodiment determines whether the engine is in a state prone to premature ignition based on engine torque TE and engine coolant temperature THW (S120~S130). Hot spots in cylinder 11, which are the cause of premature ignition, are more likely to form when engine torque TE is high and engine coolant temperature THW is high. Therefore, by using engine torque TE and engine coolant temperature THW, it is possible to accurately determine whether the engine is in a state prone to premature ignition.

[0051] (4) In this embodiment, the determination of whether a state prone to premature ignition is based on the injection pressure PF of the injector 18 (S120-S130). When the injection pressure PF is high, the amount of spray from the injector 18 is large, so the airflow in the cylinder 11 is unlikely to change the direction of the spray. Therefore, when the injection pressure PF is high, even if hydrogen is injected during premature ignition injection, premature ignition is unlikely to occur. Therefore, by using the injection pressure PF, it is possible to accurately determine whether a state prone to premature ignition is in motion.

[0052] (5) The engine 10, which uses hydrogen as fuel, can reduce NOx emissions by performing ultra-slight combustion. If hydrogen is injected during the latter half of the compression stroke, a region with a high hydrogen concentration can be formed around the spark plug 19. Therefore, the ignition properties of hydrogen can be ensured even during ultra-slight combustion. In contrast, when hydrogen is injected during the intake stroke, the hydrogen agitates the intake air more intensely compared to when it is injected during the compression stroke. Therefore, when ultra-slight combustion is performed by injecting hydrogen during the intake stroke, the hydrogen concentration around the spark plug 19 is no longer sufficient for ignition, making misfire more likely. In contrast, in this embodiment, to prevent premature ignition injection, hydrogen is injected only during the second injection period of the intake stroke if the required injection amount QS cannot be completely injected during the first injection period of the compression stroke. Therefore, misfire during ultra-slight combustion is suppressed.

[0053] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other within the scope of technical inconsistency.

[0054] • Premature ignition injection prevention can also be implemented by setting a predetermined period before the start of the compression stroke (T2) as the first injection period and a predetermined period after the intake valve 14 closes (IVC) as the second injection period. That is, premature ignition injection prevention can also be implemented as follows: First, if the required injection period TS is shorter than the period during which fuel injection can be performed before the start of the compression stroke (T2), hydrogen injection of the required injection quantity QS is performed during the period during which fuel injection can be performed before the start of the compression stroke (T2). Furthermore, if the required injection period TS is longer than the period during which fuel injection can be performed before the start of the compression stroke (T2), the hydrogen injection of the required injection quantity (QS) is divided into the "period during which fuel injection can be performed before the start of the compression stroke (T2)" and the "period during which fuel injection can be performed after the intake valve 14 closes (IVC)". In this case, hydrogen injection during the premature ignition injection period can also be avoided, thus suppressing premature ignition.

[0055] In the above embodiment, during the process of preventing premature ignition injection, if the required injection period TS is shorter than the first injection period TT (S170: No), hydrogen injection with a required injection quantity QS is performed during the first injection period (S140-S150). The smaller the required injection quantity QS, the shorter the required injection period TS. Furthermore, the lower the engine speed NE, the shorter the required injection period TS. Therefore, when the required injection period TS is shorter than the first injection period TT, the engine 10 operates at low speed or low load. Under the operating conditions of the engine 10 at low speed or low load, hot spots are less likely to occur. Therefore, in the process of preventing premature ignition injection, hydrogen injection can also be permitted during the period from the start of the compression stroke (T2) to the closing of the intake valve 14 (IVC) when the required injection period TS is shorter than the first injection period TT.

[0056] • It can also be based on a combination of parameters other than the combination of engine torque (TE), engine coolant temperature (THW), and injection pressure (PF). Figure 2 The determination in step S120.

[0057] • Alternatively, the fuel injection control routine can be implemented without determining whether the state is prone to premature ignition (S120-S130). In this case, premature ignition prevention injection is implemented regardless of whether the state is prone to premature ignition. That is, hydrogen injection is not performed during premature ignition injection, regardless of whether the state is prone to premature ignition.

[0058] The fuel injection control described above can also be applied to engines that use fuels other than hydrogen.

[0059] The electronic control unit 20 constituting the engine control device is not limited to a configuration that includes an arithmetic processing unit 21 and a storage unit 22 and performs software processing. That is, the engine control device can be any of the following configurations (a) to (c).

[0060] (a) The engine control unit has one or more processors that execute various processes according to computer programs. The processor includes a CPU and memories such as RAM and ROM. The memories store program code or instructions configured to enable the CPU to execute processes. Memory, i.e., computer-readable media, includes all available media that can be accessed by a general-purpose or special-purpose computer.

[0061] (b) The engine control unit has one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs. Furthermore, ASIC is an abbreviation for "Application Specific Integrated Circuit," and FPGA is an abbreviation for "Field Programmable Gate Array."

[0062] (c) The engine control unit has a processor that executes a portion of the various processes according to a computer program, and dedicated hardware circuitry that executes the remaining processes in the various processes.

[0063] Furthermore, the expression "at least one" as used in this specification means "more than one" of the desired options. For example, if the number of options is two, "at least one" as used in this specification means "only one option" or "both options". As another example, if the number of options is three or more, "at least one" as used in this specification means "only one option" or "any combination of two or more options".

[0064] The phrase “at least one of A and B” in this specification shall be understood to mean “A only” or “B only” or “both A and B”.

Claims

1. An engine control device, comprising a control circuit, The control circuit controls the engine, which has an injector that injects hydrogen gas as fuel into the cylinder, and the intake valve closes after the compression stroke begins. The period from the start timing of the compression stroke to the closing timing of the intake valve is defined as the premature ignition injection period, the predetermined period after the intake valve closes is defined as the first injection period, and the predetermined period before the start of the compression stroke is defined as the second injection period. The control circuit is configured to perform a determination process to determine whether the state is prone to premature ignition and a process to prevent premature ignition injection. The aforementioned treatment to prevent premature ignition injection If, during the determination process, it is determined that the state is prone to premature ignition and the required injection period (i.e., the required injection period) is longer than the first injection period, the injector is controlled to distribute the required fuel injection amount across the first and second injection periods. This results in the required hydrogen injection being performed sequentially before and after the premature ignition injection period, omitting hydrogen injection during the premature ignition injection period. If the determination process determines that the state is not prone to premature ignition, the injector is controlled to inject the required amount of hydrogen by single-stage injection, regardless of whether the required injection period is longer than the first injection period. This allows the required amount of fuel to be injected by single-stage injection during the period including both the premature ignition injection period and the first injection period.

2. The engine control device according to claim 1, The pre-premature ignition injection treatment controls the injector to inject the required amount of fuel during the first injection period if the period required for the injection of the required amount of fuel is shorter than the first injection period.

3. The engine control device according to claim 1, The determination process is based on engine torque and engine coolant temperature to determine whether the engine is in a state prone to premature ignition.

4. The engine control device according to claim 1, The determination process is based on the fuel injection pressure of the injector to determine whether the state is prone to premature ignition.

5. An engine control method, wherein the engine control method is implemented through a control circuit. The engine control method includes: Hydrogen gas, used as fuel, is injected into the cylinders of an engine using an injector. After the compression stroke begins, the intake valve is closed. The period from the start timing of the compression stroke to the closing timing of the intake valve is defined as the premature ignition injection period. The predetermined period after the intake valve closes is defined as the first injection period, and the predetermined period before the start of the compression stroke is defined as the second injection period. Determining whether a state is prone to premature ignition; as well as Prevent premature ignition and injection treatment. If, during the determination process, it is determined that the state is prone to premature ignition and the required injection period (i.e., the required injection period) is longer than the first injection period, the injector is controlled to distribute the required fuel injection amount across the first and second injection periods. This results in the required hydrogen injection being performed sequentially before and after the premature ignition injection period, omitting hydrogen injection during the premature ignition injection period. If the determination process determines that the state is not prone to premature ignition, the injector is controlled to inject the required amount of hydrogen by single-stage injection, regardless of whether the required injection period is longer than the first injection period. This allows the required amount of fuel to be injected by single-stage injection during the period including both the premature ignition injection period and the first injection period.

6. A storage medium, which is a non-transitory, computer-readable storage medium, storing a program that causes a processing device to perform engine control processing. The engine control processing is performed through a control circuit. The engine control process includes: Hydrogen gas, used as fuel, is injected into the cylinders of an engine using an injector. After the compression stroke begins, the intake valve is closed. The period from the start timing of the compression stroke to the closing timing of the intake valve is defined as the premature ignition injection period. The predetermined period after the intake valve closes is defined as the first injection period, and the predetermined period before the start of the compression stroke is defined as the second injection period. Determining whether a state is prone to premature ignition; as well as Prevent premature ignition and injection treatment. If, during the determination process, it is determined that the state is prone to premature ignition and the required injection period (i.e., the required injection period) is longer than the first injection period, the injector is controlled to distribute the required fuel injection amount across the first and second injection periods. This results in the required hydrogen injection being performed sequentially before and after the premature ignition injection period, omitting hydrogen injection during the premature ignition injection period. If the determination process determines that the state is not prone to premature ignition, the injector is controlled to inject the required amount of hydrogen by single-stage injection, regardless of whether the required injection period is longer than the first injection period. This allows the required amount of fuel to be injected by single-stage injection during the period including both the premature ignition injection period and the first injection period.

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