Engine Control Unit

Abstract

To suppress occurrence of pre-ignition.SOLUTION: An electronic control unit 20 controls an injector 18 so that fuel corresponding to a requested injection amount QS is injected in a first injection period if a period required for the fuel injection of the requested injection amount QS is shorter than the first injection period, which is a period during which fuel can be injected after the close of an intake valve 14. If the period required for the fuel injection of the requested injection amount QS is longer than the first injection period, the electronic control unit 20 controls the injector 18 so that the fuel of the requested injection amount QS is injected by dividing the injection period into the first injection period and a second injection period, which is a period during which fuel can be injected before start of a compression stroke.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an engine control device. [Background technology]

[0002] In vehicle engines, when the temperature inside the cylinder becomes high during high-load operation, the spark plugs may become hot spots, causing pre-ignition. In the engine control device described in Patent Document 1, when the occurrence of pre-ignition is detected, the amount of fuel injection is increased and the ignition timing is advanced to increase the combustion speed, thereby suppressing pre-ignition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-130473 A Summary of the Invention [Problem to be solved by the invention]

[0004] The normal control target values ​​for the engine fuel injection amount and ignition timing are set to optimal values ​​in terms of fuel economy and exhaust performance, so increasing the fuel injection amount or advancing the ignition timing will result in a deterioration in the engine fuel economy and exhaust performance. [Means for solving the problem]

[0005] The engine control device that solves the above problem is a device that controls an engine that has an injector that injects fuel into a cylinder and closes an intake valve after the start of the compression stroke. Here, one of a predetermined period before the start of the compression stroke and a predetermined period after the intake valve closes is defined as a first injection period and the other is defined as a second injection period. When the period required to inject fuel of a required injection amount is longer than the first injection period, the engine control device performs a plague prevention injection process that divides the period into the first injection period and the second injection period and controls the injector to inject fuel of the required injection amount.

[0006] At the top of the cylinder of an engine, there are parts such as exhaust valves and spark plugs that are prone to become hot spots during engine operation. On the other hand, during the compression stroke, the piston rises in the cylinder and pushes up the intake air in the cylinder. At this time, if the intake valve is open, the intake air in the cylinder escapes to the intake port, and an upward airflow occurs in the cylinder. If fuel is injected during the period when such an airflow occurs, the fuel spray rides on the airflow and moves upward in the cylinder. At this time, if the exhaust valve, the spark plug, etc. are at a high temperature, the fuel spray may come into contact with them and ignite, causing pre-ignition. That is, in an engine in which the intake valve closes after the start of the compression stroke, pre-ignition is likely to occur if fuel is injected into the cylinder during the period from the start of the compression stroke to the closing of the intake valve.

[0007] In the above-mentioned plague prevention injection process, if the required injection amount of fuel cannot be injected within the first injection period, the injector is controlled to inject the required injection amount of fuel by dividing the first injection period into the first injection period and the second injection period. That is, in the plague prevention injection process, fuel is injected while avoiding the period from the start of the compression stroke to the closing of the intake valve, during which pre-ignition is likely to occur if fuel is injected. This makes it difficult for pre-ignition to occur.

[0008] The above-mentioned plague prevention injection process may be configured to control the injector to inject the required injection amount of fuel during the first injection period when the period required to inject the required injection amount of fuel is shorter than the first injection period. By configuring the plague prevention injection process in this manner, even when the period required to inject the required injection amount of fuel is shorter than the first injection period, fuel injection is performed while avoiding the period during which pre-ignition is likely to occur if fuel is injected.

[0009] Depending on the operating state of the engine, pre-ignition may not occur easily even if fuel is injected during the period from the start of the compression stroke to the closing of the intake valve. Therefore, a determination process may be performed to determine whether or not pre-ignition is likely to occur, and the above-mentioned pre-ignition prevention injection process may be performed only when the determination process determines that pre-ignition is likely to occur. When the engine torque is large or the engine water temperature is high, the temperature inside the cylinder increases and pre-ignition is likely to occur. Therefore, the determination of whether or not pre-ignition is likely to occur in the above-mentioned determination process may be performed based on the engine torque and the engine water 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 sufficiently high, the spray is unlikely to enter the cylinder, and pre-ignition is unlikely to occur. Therefore, the determination of whether or not pre-ignition is likely to occur in the above-mentioned determination process may be performed based on the fuel injection pressure of the injector.

[0010] The engine control device may be configured so that a predetermined period after the intake valve is closed is set as the first injection period. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a schematic configuration of an embodiment of an engine control device; [Diagram 2] 3 is a flowchart of a fuel injection control routine executed by the engine control device. [Diagram 3]FIG. 1 is a time chart showing, in each of the figures, (A) the open / closed state of the intake valve, (B) the implementation status of fuel injection when the required injection period is equal to or shorter than the first injection period, (C) the implementation status of fuel injection when the engine is not operating in the plague operation range and the required injection period is longer than the first injection period, and (D) the implementation status of fuel injection when the engine is operating in the plague operation range and the required injection period is longer than the first injection period. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of an engine control device will be described in detail with reference to FIGS. <Engine control unit configuration> First, the configuration of the engine control device of this embodiment will be described with reference to Fig. 1. An engine 10 to be controlled by the engine control device of this embodiment is mounted on a vehicle. The engine 10 is configured as a hydrogen gas engine that uses hydrogen gas as fuel.

[0013] The engine 10 has a cylinder 11. Inside the cylinder 11, a piston 12 is arranged so as to be able to reciprocate up and down in the drawing. Inside the cylinder 11, a combustion chamber 13 in which combustion occurs is defined by the piston 12. An intake port 15 is connected to the top of the cylinder 11 via an intake valve 14. Also, an exhaust port 17 is connected to the top of the cylinder 11 via an exhaust valve 16. Furthermore, an injector 18 that injects hydrogen gas into the cylinder 11 and an ignition plug 19 that ignites the hydrogen gas injected by the injector 18 are provided at the top of the cylinder 11. The valve timing of the intake valve 14 in this engine 10 is set so that the valve closing timing occurs after the start of the compression stroke.

[0014] The electronic control unit 20 that controls the engine 10 includes an arithmetic processing device 21 and a storage device 22. The storage device 22 stores programs and data used for control. The arithmetic processing device 21 executes the programs read from the storage device 22 to perform various processes related to the control of the engine 10. In this embodiment, the electronic control unit 20 corresponds to an engine control device.

[0015] The electronic control unit 20 is connected to a crank angle sensor 23, an air flow meter 24, a water temperature sensor 25, an accelerator pedal sensor 26, and a fuel pressure sensor 27. The crank angle sensor 23 is a sensor that detects the rotation phase of the crankshaft of the engine 10. The air flow meter 24 is a sensor that detects the amount of intake air of the engine 10. The water temperature sensor 25 is a sensor that detects the engine water temperature THW, which is the temperature of the cooling water of the engine 10. The accelerator pedal sensor 26 is a sensor that detects the accelerator pedal operation amount ACC by the driver. The fuel pressure sensor 27 is a sensor that detects the pressure of the fuel supplied to the injector 18. The electronic control unit 20 obtains the engine speed NE, which is the rotation speed of the engine 10, from the detection result of the crank angle sensor 23. The electronic control unit 20 also obtains an engine load factor KL based on the intake air amount detected by the air flow meter 24 and the engine speed NE. The engine load factor KL represents the intake air filling rate of the combustion chamber 13. Furthermore, the electronic control unit 20 determines the fuel injection pressure PF of the injector 18 based on the detection result of the fuel pressure sensor 27. In addition to the above, various sensors installed in various parts of the vehicle are connected to the electronic control unit 20.

[0016] <Fuel injection control> As part of engine control, the electronic control unit 20 controls the fuel injection of the injector 18. The fuel injection control will be described in detail below.

[0017] FIG. 2 shows a flowchart of a fuel injection control routine executed by the electronic control unit 20 for fuel injection control. During operation of the engine 10, the electronic control unit 20 repeatedly executes this routine at a predetermined control cycle. Note that the values ​​of each timing shown in FIG. 2 represent the amount of advance of the crank angle from the compression top dead center. Thus, a timing with a larger value is earlier than a timing with a smaller value. Also, the values ​​of each period shown in FIG. 2 and FIG. 3 represent the amount of rotation of the crankshaft during the corresponding period.

[0018] When this routine starts, first in step S100, the electronic control unit 20 calculates a required injection amount QS based on the engine speed NE, the accelerator pedal depression amount ACC, etc. The required injection amount QS is a required value for the amount of hydrogen gas injected by the injector 18.

[0019] Next, in step S110, the electronic control unit 20 calculates a required injection period TS based on the required injection amount QS, the engine speed NE, and the injection pressure PF. The required injection period TS represents a value obtained by converting the time required for hydrogen gas injection of the required injection amount QS into a crankshaft rotation angle for the same time at the current engine speed NE. The crank angle represents the rotation angle of the crankshaft, which is the output shaft of the engine 10. Note that the injection rate of hydrogen gas from the injector 18, i.e., the amount of hydrogen gas injected per unit time, increases as the injection pressure PF increases. Therefore, when the required injection amount QS is constant and the engine speed NE is constant, the required injection period TS becomes longer as the injection pressure PF decreases. Also, the crankshaft rotation angle per unit time increases as the engine speed NE increases. Therefore, when the required injection amount QS is constant and the injection pressure PF is constant, the required injection period TS becomes shorter as the engine speed NE increases.

[0020] Next, in step S120, the electronic control unit 20 determines whether the engine 10 is operating in the pre-ignition operation range. The pre-ignition operation range represents an operation range of the engine 10 in which pre-ignition is likely to occur. Pre-ignition is more likely to occur when the ignition plug 19 or the exhaust valve 16 is at a high temperature. When the engine torque TE is high, more fuel is burned in the cylinder 11 than when the engine torque TE is low. Therefore, when the engine torque TE is high, pre-ignition is more likely to occur than when the engine torque TE is low. In addition, when the temperatures of the ignition plug 19 or the exhaust valve 16 are high, the engine water temperature THW also becomes high. Therefore, when the engine water temperature THW is high, pre-ignition is more likely to occur than when the engine water temperature THW is low. On the other hand, as described later, when the injection pressure PF is low, pre-ignition is more likely to occur than when the injection pressure PF is high. Therefore, in this embodiment, it is determined whether or not the engine 10 is operating in the plague operation range based on the engine torque TE, the engine water temperature THW, and the injection pressure PF.

[0021] If the engine 10 is not operating in the plunging operation range (S130: NO), the electronic control unit 20 proceeds to step S140. In step S140, the electronic control unit 20 sets the value of the first injection end time IE1 to a time earlier than the final injection end time T1 by the injection stop margin TM (EI1←T1+TM). In step S140, the electronic control unit 20 also sets the value of the first injection start time IS1 to a time earlier than the first injection end time IE1 by the required injection period TS (SI1←EI1+TS). In step S150, the electronic control unit 20 commands the injector 18 to perform single-stage injection of hydrogen gas during the period from the first injection start time IS1 to the first injection end time IE1, and then ends the processing of this routine in the current control cycle.

[0022] The final injection end time T1 is the end time of a period during which hydrogen gas injection is permissible. In this embodiment, the final injection end time T1 is the time when the piston 12 is at top dead center of compression. There is a delay between the injection stop command from the electronic control unit 20 and the injector 18 actually stopping hydrogen gas injection. The injection stop margin TM represents the injection stop delay time converted into the crankshaft rotation angle for that 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.

[0023] On the other hand, when the engine 10 is operating in the plunging operation 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 intake valve 14 closing timing IVC to the final injection end timing T1 is set as T0. The first injection period TT is the period T0 minus the injection stop margin TM, expressed in crank angle. Such a first injection period TT represents the period during which fuel injection is possible after the intake valve 14 is closed. Then, in the following 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 equal to or shorter than the first injection period TT (S170: NO), the electronic control unit 20 proceeds to the above-mentioned step S140. On the other hand, if the necessary injection period TS is longer than the first injection period TT (S170: YES), the electronic control unit 20 advances the process to step S180.

[0024] When the process proceeds to step S180, the electronic control unit 20 sets the value of the first injection end timing IE1 to a timing earlier than the final injection end timing T1 by the injection stop margin TM in step S180. Also, 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. Furthermore, in step S180, the electronic control unit 20 sets the value of the second injection end timing IE2 to a timing earlier than the start timing T2 of the compression stroke by the injection stop margin TM (IE2←T2+TM). In addition, in step S180, the electronic control unit 20 sets the value of the second injection start timing IS2 to a timing earlier than the start timing T2 of the compression stroke by the difference (=TS-TT) between the required injection period TS and the first injection period TT (IS←IE2+TS-TT). Then, in the next step S190, the electronic control unit 20 commands the injector 18 to perform split injection in two periods: the period from the second injection start time IS2 to the second injection end time IE2, and the period from the first injection start time IS1 to the first injection end time IE1. After issuing the commands, the electronic control unit 20 ends the processing of this routine in the current control cycle.

[0025] In this embodiment, the processes of steps S140 to S190 in the fuel injection control routine correspond to the pre-ignition prevention injection process. Also, the processes of steps S120 and S130 correspond to the determination process for determining whether or not the engine is in a state where pre-ignition is likely to occur.

[0026] <Effects of the embodiment> The operation and effect of this embodiment will be described. In the following description, the period during which fuel injection is possible after the closing timing IVC of the intake valve 14 is referred to as the first injection period. Also, the period during which fuel injection is possible before the start timing T2 of the compression stroke is referred to as the second injection period. In this embodiment, the length of the first injection period is described as the "first injection period TT."

[0027] FIG. 3A shows the transition of the open / close state of the intake valve 14 in the engine 10. The values ​​on the horizontal axis in FIG. 3 represent the advance amount [° BTDC] of the crank angle relative to the end of the compression stroke. Here, the compression stroke is defined as the period from when the piston 12 is at the bottom dead center of the intake stroke to when it is at the top dead center of the compression stroke. As shown in FIG. 3A, the closing timing IVC of the intake valve 14 in the engine 10 is set to a time later than the start timing T2 of the compression stroke. That is, in the engine 10, there is a period during which the intake valve 14 is open after the start of the compression stroke. If the intake valve 14 is open during the compression stroke in which the piston 12 rises in the cylinder 11, the intake air in the cylinder 11, which is pressed by the piston 12, escapes to the intake port 15, generating an upward airflow in the cylinder 11.

[0028] On the other hand, when the engine 10 is operating under high load, the ignition plug 19, the exhaust valve 16, etc. become hot, and a hot spot that can become a source of fire is formed in the upper part of the cylinder 11. At this time, if the injector 18 injects hydrogen gas while the intake valve 14 is open during the compression stroke, the spray is carried by the air current toward the upper part of the cylinder 11. Then, the spray may come into contact with the hot spot formed in the upper part of the cylinder 11, causing pre-ignition. In this way, if hydrogen gas is injected while the intake valve 14 is open during the compression stroke, pre-ignition is likely to occur. In the following description, the period from the start time T2 of the compression stroke to the closing time IVC of the intake valve 14 is referred to as the pre-ignition injection period.

[0029] In step S170 of the fuel injection control routine in FIG. 2, 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 amount QS under the current engine speed NE and injection pressure PF. That is, in step S170, it is determined whether the period required for fuel injection of the required injection amount QS is longer than the first injection period TT. If the required injection period TS is longer than the first injection period TT, the hydrogen gas of the required injection amount QS cannot be injected within the first injection period TT. In this case, if hydrogen gas of the required injection amount QS is to be injected at once, that is, if hydrogen gas injection of the required injection amount QS is to be performed in a single stage injection, hydrogen gas injection will be performed during the pre-ignition injection period.

[0030] When the engine torque TE or the engine water temperature THW is low, the spark plug 19 and the exhaust valve 16 do not become hot enough to ignite the spray. Therefore, in such cases, even if hydrogen gas is injected during the pre-ignition period, pre-ignition is unlikely to occur. Also, the higher the injection pressure PF of the injector 18, the greater the momentum of the spray. Therefore, when the injection pressure PF is at a certain level or higher, the change in the direction of the spray caused by the airflow in the cylinder 11 becomes small, so that pre-ignition is unlikely to occur even if hydrogen gas is injected during the pre-ignition period.

[0031] 2, the electronic control unit 20 determines whether or not the engine 10 is operating in the pre-ignition operation range based on the engine torque TE, the engine water temperature THW, and the injection pressure PF. As described above, the pre-ignition operation range represents the operating range of the engine 10 in which pre-ignition is likely to occur. Therefore, in step S120, a determination process is performed to determine whether or not the engine 10 is in a state in which pre-ignition is likely to occur based on the engine torque TE, the engine water temperature THW, and the injection pressure PF.

[0032] 2, when the electronic control unit 20 determines in step S120 that the engine 10 is operating in the plague operation range, it performs the determination in step S170. Then, when the required injection period TS is shorter than or equal to the first injection period TT, the electronic control unit 20 performs the processes in steps S140 and S150. In this case, hydrogen gas is injected in a single stage injection, and the single stage injection is terminated at the first injection end timing IE1.

[0033] An example of the implementation status of fuel injection in this case is shown in Figure 3(B). In this case, since the required injection period TS is shorter than the first injection period TT, hydrogen gas injection of the required injection amount QS is performed within the first injection period TT. Therefore, in this case, hydrogen gas injection during the plague injection period is not performed.

[0034] On the other hand, when the electronic control unit 20 determines in step S170 that the necessary injection period TS is longer than the first injection period TT, it executes the processes of steps S180 and S190. In this case, hydrogen gas is injected throughout the first injection period after the intake valve 14 opens, and hydrogen gas is injected in portions so that the amount of hydrogen gas that is not enough is injected during the second injection period before the start of the compression stroke.

[0035] An example of the implementation status of fuel injection in this case is shown in Figure 3 (D). In this case, hydrogen gas is injected in the required injection amount QS in separate injections before and after the plague injection period. Therefore, hydrogen gas is not injected during the plague injection period in this case either.

[0036] If it is determined in step S120 that the state is not prone to pre-ignition, the electronic control unit 20 performs hydrogen gas injection through the processes of steps S140 and S150. In this case, hydrogen gas injection of the required injection amount QS is performed by single-stage injection, regardless of whether the required injection period TS is longer than the first injection period TT.

[0037] Figure 3(C) shows an example of the implementation status of fuel injection in this case. Note that the example of Figure 3(C) is a case where the required injection period TS is longer than the first injection period TT. In this case, hydrogen gas 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, hydrogen gas injection may also be performed during the pre-ignition injection period. However, in this case, even if hydrogen gas is injected during the pre-ignition injection period, pre-ignition is unlikely to occur.

[0038] According to the engine control device of the present embodiment described above, the following effects can be achieved. (1) In this embodiment, the plague prevention injection process is performed to control the injector 18 in the following manner. That is, in the plague prevention injection process, when the period required for fuel injection of the required injection amount QS is shorter than the first injection period TT, the injector 18 is controlled to inject fuel of the required injection amount QS during the first injection period. In addition, in the plague prevention injection process, when the period required for fuel injection of the required injection amount QS is longer than the first injection period TT, the injector 18 is controlled to inject fuel of the required injection amount QS by dividing the period into the first injection period and the second injection period. As a result, hydrogen gas injection is not performed during the plague injection period during which pre-ignition is likely to occur. Therefore, the engine control device of this embodiment has the effect of suppressing the occurrence of pre-ignition.

[0039] (2) In this embodiment, it is determined whether or not the state is such that pre-ignition is likely to occur. Then, only when it is determined that the state is such that pre-ignition is likely to occur, the above-mentioned pre-ignition prevention injection process is performed. In other words, when the state is not such that pre-ignition is likely to occur, hydrogen gas injection during the pre-ignition injection period is permitted. Then, as a result, even when the necessary injection period TS is longer than the first injection period TT, single-stage injection is performed without split injection. The drive current of the injector 18 is large at the start of injection. Therefore, by not performing split injection, the power consumption for driving the injector 18 is suppressed. In addition, the variation in the hydrogen gas injection rate of the injector 18 increases during the period immediately after the start of injection and immediately before the end of injection. Therefore, by reducing the number of injections without performing split injection, the accuracy of the hydrogen gas injection amount can be improved. Furthermore, by reducing the number of injections without performing split injection, wear of the nozzle seat due to the nozzle seating at the end of injection of the injector 18 is also suppressed.

[0040] (3) In this embodiment, whether or not a state in which pre-ignition is likely to occur is determined based on engine torque TE and engine water temperature THW. Hot spots in cylinder 11 that cause pre-ignition are likely to form when engine torque TE or engine water temperature THW is high. Therefore, based on engine torque TE and engine water temperature THW, it is possible to accurately determine whether or not a state in which pre-ignition is likely to occur.

[0041] (4) In this embodiment, whether or not a state in which pre-ignition is likely to occur is determined based on the injection pressure PF of the injector 18. When the injection pressure PF is high, the momentum of the spray is large, so the direction of the spray is less likely to change due to the airflow inside the cylinder 11. Therefore, when the injection pressure PF is high, pre-ignition is less likely to occur even if hydrogen gas is injected during the pre-ignition injection period. Therefore, based on the injection pressure PF, it is possible to accurately determine whether or not a state in which pre-ignition is likely to occur is present.

[0042] (5) In the engine 10 using hydrogen gas as fuel, the amount of NOx emissions can be reduced by performing ultra-lean combustion. When hydrogen gas is injected in the latter half of the compression stroke, a region with a high concentration of hydrogen gas can be formed around the spark plug 19, so that the ignition of hydrogen gas can be ensured even during ultra-lean combustion. In contrast, when hydrogen gas is injected during the intake stroke, the hydrogen gas is stirred into the intake air more than when hydrogen gas is injected during the compression stroke. Therefore, when hydrogen gas is injected during the intake stroke to perform ultra-lean combustion, the hydrogen gas concentration around the spark plug 19 does not reach the concentration required for ignition, and misfires are likely to occur. In contrast, in this embodiment, in the plague prevention injection process, hydrogen gas is injected during the second injection period during the intake stroke only when the hydrogen gas equivalent to the required injection amount QS cannot be completely injected during the first injection period during the compression stroke. Therefore, misfires during ultra-lean combustion are suppressed.

[0043] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction. The plague prevention injection process may be performed with a predetermined period before the start of the compression stroke as the first injection period and a predetermined period after the intake valve 14 is closed as the second injection period. That is, the plague prevention injection process may be performed in the following manner. First, when the required injection period TS is shorter than the period during which fuel injection is possible before the start of the compression stroke, hydrogen gas injection is performed for the required injection amount QS during the period during which fuel injection is possible before the start of the compression stroke. Then, when the required injection period TS is longer than the period during which fuel injection is possible before the start of the compression stroke, hydrogen gas injection is performed for the required injection amount QS by dividing the period into the period during which fuel injection is possible before the start of the compression stroke and the period during which fuel injection is possible after the intake valve 14 is closed. Even in such a case, hydrogen gas injection during the plague injection period can be avoided, so that the occurrence of pre-ignition can be suppressed.

[0044] In the above embodiment, in the plague prevention injection process, when the required injection period TS is shorter than the first injection period TT, hydrogen gas injection of the required injection amount QS is performed during the first injection period. The required injection period TS becomes shorter as the required injection amount QS becomes smaller. Also, the required injection period TS becomes shorter as the engine speed NE becomes lower. Therefore, when the required injection period TS is shorter than the first injection period TT, the engine 10 is operated at low speed and low load. Hot spots are unlikely to occur under the operating conditions of the engine 10 at low speed and low load. Therefore, in the plague prevention injection process, when the required injection period TS is shorter than the first injection period TT, hydrogen gas injection may be permitted during the period from the start of the compression stroke to the closing of the intake valve 14.

[0045] The determination in step S120 in FIG. 2 may be made based on a combination of parameters other than the combination of the engine torque TE, the engine water temperature THW, and the injection pressure PF. The fuel injection control routine may be executed without determining whether or not the state is prone to pre-ignition. In this case, the pre-ignition prevention injection process is executed regardless of whether or not the state is prone to pre-ignition. In other words, hydrogen gas injection during the pre-ignition injection period is not executed regardless of whether or not the state is prone to pre-ignition.

[0046] The fuel injection control in the above embodiment may also be applied to engines that use fuels other than hydrogen gas. [Explanation of symbols]

[0047] 10…Engine 11…Cylinder 12…Piston 13…Combustion chamber 14…Intake valve 15…Intake port 16...Exhaust valve 17…Exhaust port 18…Injector 19…Spark plug 20...Electronic control unit 21...Processing device 22…Storage device 23...Crank angle sensor 24...Air flow meter 25...Water temperature sensor 26...Accelerator pedal sensor 27...Fuel pressure sensor

Claims

1. A device for controlling an engine having an injector that injects hydrogen gas as fuel into a cylinder and in which an intake valve is closed after the start of a compression stroke, When a period from the start of the compression stroke to the closing of the intake valve is defined as a pre-ignition injection period, a predetermined period after the intake valve is closed is defined as a first injection period, and a predetermined period before the start of the compression stroke is defined as a second injection period, A determination process for determining whether or not a state in which pre-ignition is likely to occur is being performed; a pre-ignition prevention injection process for controlling the injector to inject the required injection amount of fuel in a divided manner into the first injection period and the second injection period when the determination process determines that the state is prone to pre-ignition and the period required to inject the required injection amount of fuel is longer than the first injection period, and for controlling the injector to inject the required injection amount of fuel in a single stage manner in a period including at least the pre-ignition injection period and the first injection period when the determination process determines that the state is not prone to pre-ignition and the period required to inject the required injection amount of fuel is longer than the first injection period; An engine control device that performs the above.

2. 2. The engine control device according to claim 1, wherein the plague prevention injection process controls the injector so as to inject the required injection amount of fuel during the first injection period when a period required for fuel injection of the required injection amount is shorter than the first injection period.

3. 3. The engine control device according to claim 1, wherein the determination process determines whether or not the engine is in a state where pre-ignition is likely to occur based on an engine torque and an engine water temperature.

4. 3. The engine control device according to claim 1, wherein the determination process determines whether or not the engine is in a state where pre-ignition is likely to occur based on a fuel injection pressure of the injector.

5. The engine control device according to claim 1 , wherein the first injection period is a predetermined period after the intake valve is closed.

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