Control device for internal combustion engine

Abstract

To suppress combustion of hydrogen gas within a sensor.SOLUTION: An internal combustion engine 10 uses hydrogen as fuel. The internal combustion engine 10 comprises an exhaust passage 90 and an air-fuel ratio sensor 55 for detecting an air-fuel ratio, which is provided in the exhaust passage 90 and has a heater 55H. A control device 100 executes suppression processing to suppress heating by the heater 55H when a specified condition under which the concentration of hydrogen gas flowing into the exhaust passage 90 may exceed a predetermined value is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for an internal combustion engine. [Background technology]

[0002] A sensor for detecting an air-fuel ratio is provided in an exhaust passage of an internal combustion engine, and this sensor is provided with a heater to quickly activate the detection element (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-229899 Summary of the Invention [Problem to be solved by the invention]

[0004] In an internal combustion engine that uses hydrogen as fuel, the concentration of unburned hydrogen gas flowing into the exhaust passage may exceed a predetermined value. Therefore, if the above-described sensor is installed in the exhaust passage and heated by a heater, there is a risk that the unburned hydrogen gas will be burned inside the sensor. [Means for solving the problem]

[0005] The control device for an internal combustion engine that solves the above problem is a control device applied to an internal combustion engine that uses hydrogen as fuel. The internal combustion engine includes an exhaust passage and a sensor that detects an air-fuel ratio and has a heater provided in the exhaust passage. The control device executes a suppression process to suppress heating of the heater when a specified condition is met that indicates that the concentration of hydrogen gas flowing into the exhaust passage may exceed a predetermined value.

[0006] According to this configuration, when there is a possibility that the concentration of hydrogen gas flowing into the exhaust passage will exceed a predetermined value, the heater of the sensor installed in the exhaust passage is suppressed from heating. When the heater's heating is suppressed, the temperature of the sensor decreases, thereby suppressing the combustion of hydrogen gas within the sensor. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing the configuration of an internal combustion engine according to a first embodiment. [Figure 2] 4 is a flowchart showing a procedure of a process executed by the control device of the embodiment. [Figure 3] 10 is a flowchart showing the procedure of a process executed by a control device of a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A first embodiment of a control device for an internal combustion engine will be described below. (First embodiment) <Configuration of an internal combustion engine> 1, an internal combustion engine 10 includes a cylinder block 11, a cylinder head 12, a head cover 13, and an oil pan 14. The cylinder block 11 includes a cylinder 16 in which a piston 15 is arranged so as to be able to reciprocate.

[0009] The cylinder head 12 is provided with an intake port 30 that introduces intake air into a combustion chamber 17 of the internal combustion engine 10, and an exhaust port 70 that discharges exhaust gas from the combustion chamber 17. An intake valve 81 is provided in the intake port 30. The drive system of this intake valve 81 is provided with an intake-side variable valve timing mechanism 85, which is a variable valve mechanism that changes the valve timing (opening and closing timing) of the intake valve 81. An exhaust valve 82 is provided in the exhaust port 70. The drive system of this exhaust valve 82 is provided with an exhaust-side variable valve timing mechanism 86, which is a variable valve mechanism that changes the valve timing (opening and closing timing) of the exhaust valve 82.

[0010] The cylinder head 12 is also provided with a port injection valve 83 that injects hydrogen as fuel into the intake port 30, an in-cylinder injection valve 84 that directly injects hydrogen as fuel into the combustion chamber 17, and an ignition plug (not shown).

[0011] A crankcase 19 is provided below the cylinder block 11. The crankcase 19 houses a crankshaft 18, which is the output shaft of the internal combustion engine 10. An oil pan 14 that stores lubricating oil is provided below the crankcase 19.

[0012] An intake manifold 29 equipped with a surge tank 60 is connected upstream of the intake port 30, and an intake pipe 20 is connected upstream of the surge tank 60. The intake pipe 20, the surge tank 60, and the intake manifold 29 form an intake passage of the internal combustion engine 10.

[0013] In the intake pipe 20, there are installed, in order from upstream, an air cleaner 21, an air flow meter 22, a compressor wheel 24C of a supercharger 24 driven by exhaust gas discharged from the combustion chamber 17, an intercooler 27, a supercharging pressure sensor 25, and a throttle valve 28. In addition, an intake pressure sensor 54 is installed in the surge tank 60. The opening of the throttle valve 28 is changed by an electric motor.

[0014] The air cleaner 21 filters the intake air taken into the intake pipe 20. The supercharger 24 supercharges the air in the intake pipe 20. The intercooler 27 cools the air after it has passed through the compressor wheel 24C. The throttle valve 28 adjusts the amount of intake air by adjusting the valve opening.

[0015] The air flow meter 22 detects the intake air amount GA. The boost pressure sensor 25 detects the boost pressure PTC, which is the pressure in the intake pipe 20 downstream of the compressor wheel 24C. The intake pressure sensor 54 detects the intake pressure PIM, which is the pressure in the surge tank 60.

[0016] An exhaust passage 90 is connected downstream of the exhaust port 70. A housing that accommodates a turbine wheel 24T of the turbocharger 24 is connected to the exhaust passage 90. Furthermore, a portion of the exhaust passage 90 upstream of the turbine wheel 24T and a portion of the exhaust passage 90 downstream of the turbine wheel 24T are connected via a bypass passage 92. A wastegate valve (hereinafter referred to as WGV) 93, the opening of which is adjusted by an actuator, is provided in the bypass passage 92. This WGV 93 is a valve that adjusts the amount of exhaust gas flowing through the bypass passage 92, and the larger the opening of the WGV 93, the greater the amount of exhaust gas that bypasses the turbine wheel 24T and passes through the bypass passage 92. Therefore, the boost pressure of the intake air increased by the turbocharger 24 becomes lower.

[0017] A catalyst 95 for purifying exhaust gas is provided in the exhaust passage 90 downstream of the bypass passage 92. An air-fuel ratio sensor 55 for outputting an air-fuel ratio signal corresponding to the oxygen concentration in the exhaust gas and the amount of unburned fuel is also provided in the exhaust passage 90 upstream of the catalyst 95. The air-fuel ratio sensor 55 is provided with a heater 55H for heating a detection element of the air-fuel ratio sensor 55.

[0018] The internal combustion engine 10 is provided with a blow-by gas treatment device that treats gas that leaks from the combustion chamber 17 into the crankcase 19 during the compression stroke or the combustion stroke, i.e., so-called blow-by gas. This blow-by gas treatment device has a suction passage 32 that guides the blow-by gas in the crankcase 19 to a main separator 31, which is an oil separator provided in the head cover 13. The end of the suction passage 32 connected to the main separator 31 opens into the crankcase 19.

[0019] The main separator 31 is connected to the surge tank 60 via a PCV (positive crankcase ventilation) valve 34, which is a differential pressure valve, and a PCV passage 35. The PCV valve 34 opens when the pressure in the surge tank 60 becomes lower than the pressure in the main separator 31, allowing blow-by gas to flow from the main separator 31 into the surge tank 60. The suction passage 32, main separator 31, PCV valve 34, and PCV passage 35 form a communication passage that communicates between the surge tank 60, which forms part of the intake passage, and the crankcase 19.

[0020] For example, when the boost pressure of the turbocharger 24 is low, the pressure in the surge tank 60 becomes lower than the pressure in the main separator 31. Therefore, the blow-by gas in the crankcase 19 is sucked into the surge tank 60 via the suction passage 32, the main separator 31, the PCV valve 34, and the PCV passage 35. The sucked blow-by gas is sent to the combustion chamber 17 together with the intake air and is burned.

[0021] An ejector 40 is connected to the main separator 31 via a connecting passage 41. The ejector 40 is provided in the middle of a bypass passage 36 that connects the intake pipe 20 upstream of the compressor wheel 24C with the intake pipe 20 downstream of the compressor wheel 24C. The ejector 40 has a throttle portion for generating negative pressure by the Venturi effect.

[0022] The blow-by gas treatment device also has an atmosphere introduction passage 37 for introducing intake air into the crankcase 19 for scavenging. One end of the atmosphere introduction passage 37 is connected to the intake pipe 20 between the air cleaner 21 and the compressor wheel 24C. The atmosphere introduction passage 37 penetrates the head cover 13, passes through the inside of the cylinder head 12 and the cylinder block 11, and is connected to the crankcase 19. An atmosphere-side separator 38, which is an oil separator installed inside the head cover 13, is provided midway along the atmosphere introduction passage 37.

[0023] When the supercharging pressure of the supercharger 24 is high, air flows through the bypass passage 36 from the downstream side to the upstream side of the compressor wheel 24C, generating a negative pressure in the ejector 40. Then, due to the negative pressure generated in the ejector 40, blow-by gas in the crankcase 19 is sucked into the inside of the ejector 40 via the suction passage 32, the main separator 31, and the connecting passage 41. The blow-by gas sucked into the ejector 40 is introduced together with air through the bypass passage 36 into the intake pipe 20 upstream of the compressor wheel 24C. The blow-by gas introduced into the intake pipe 20 is sent to the combustion chamber 17 together with intake air and is burned.

[0024] The control device 100 controls the internal combustion engine 10 and operates various devices such as the throttle valve 28, port injection valve 83, in-cylinder injection valve 84, spark plug, intake side variable valve timing mechanism 85, exhaust side variable valve timing mechanism 86, and WGV 93.

[0025] The control device 100 includes a central processing unit (hereinafter referred to as CPU) 110, a memory 120 in which control programs and data are stored, etc. The control device 100 performs various control-related processes by having the CPU 110 execute the programs stored in the memory 120.

[0026] The control device 100 receives detection signals from the air flow meter 22, the boost pressure sensor 25, the intake pressure sensor 54, and the air-fuel ratio sensor 55. The control device 100 also receives a detection signal from a crank angle sensor 51 that detects the rotation angle (crank angle) of the crankshaft 18 to calculate the engine speed NE. The control device 100 also receives detection signals from a vehicle speed sensor 53 that detects the vehicle speed SP of the vehicle equipped with the internal combustion engine 10, an accelerator operation amount sensor 52 that detects the accelerator pedal operation amount ACP, and the like. The control device 100 calculates an engine load factor KL based on the engine speed NE and the intake air amount GA. The engine load factor KL is a parameter that determines the amount of air charged into the combustion chamber 17 and is the ratio of the inflow air amount per combustion cycle of one cylinder to a reference inflow air amount. The reference inflow air amount is variably set according to the engine speed NE.

[0027] The control device 100 calculates a target output Pe, which is a target value of the output required of the internal combustion engine 10, based on the accelerator operation amount ACP and the vehicle speed SP. When the target output Pe is large, the control device 100 executes control to reduce the air-fuel ratio of the mixture compared to when the target output Pe is small. More specifically, the control device 100 basically maintains the throttle valve 28 at an opening equal to or greater than a predetermined value, for example, an opening close to full opening. The control device 100 sets the required injection amount Qd so that the required injection amount Qd increases as the target output Pe increases. The required injection amount Qd is a target value for the fuel injected from the port injection valve 83 and the in-cylinder injection valve 84. The control device 100 controls the port injection valve 83 and the in-cylinder injection valve 84 to obtain the required injection amount Qd. In this way, the internal combustion engine 10 adjusts the output by changing the air-fuel ratio of the mixture through adjustment of the fuel injection amount.

[0028] When the target output Pe is "0", the control device 100 automatically stops the operation of the internal combustion engine 10. After the automatic stop, when the target output Pe becomes greater than "0", the control device 100 starts the internal combustion engine 10 to resume operation. In this way, the control device 100 executes the automatic stop and automatic start of the internal combustion engine 10.

[0029] The control device 100 also calculates target valve timings for the intake valve 81 and the exhaust valve 82 based on the engine speed NE, the engine load factor KL, etc. Then, based on the target valve timings, the control device 100 controls the drive of the intake-side variable valve timing mechanism 85 and the exhaust-side variable valve timing mechanism 86.

[0030] The control device 100 also calculates the target supercharging pressure PTCp based on the engine rotation speed NE, the engine load factor KL, etc. Then, the control device 100 adjusts the opening degree of the WGV 93 based on the target supercharging pressure PTCp, etc., thereby controlling the supercharging pressure of the supercharger 24.

[0031] <Suppression Processing of This Embodiment> In an internal combustion engine 10 that uses hydrogen as fuel, the concentration of hydrogen gas flowing into the exhaust passage 90 may exceed a predetermined combustible value. For example, during the period from when the internal combustion engine begins to start until combustion of the air-fuel mixture stabilizes, the amount of unburned hydrogen gas contained in the exhaust increases, and the concentration of hydrogen gas flowing into the exhaust passage 90 may exceed a predetermined value. If the heater 55H of the air-fuel ratio sensor 55 is heated in such a situation where the concentration of hydrogen gas is higher than the predetermined value, the unburned hydrogen gas may be burned within the air-fuel ratio sensor 55.

[0032] Therefore, the start of the internal combustion engine 10 is set as a specified condition under which the concentration of hydrogen gas flowing into the exhaust passage 90 may exceed a predetermined value. When this specified condition is met, the control device 100 executes a suppression process to suppress heating of the heater 55H.

[0033] Fig. 2 shows the processing procedure for executing the suppression processing. The processing shown in Fig. 2 is realized by the control device 100 repeatedly executing it at predetermined intervals. Note that, below, the step number of each processing is represented by a number preceded by "S."

[0034] In the series of processes shown in Fig. 2, the control device 100 first determines whether or not the engine is being started (S100). The control device 100 makes a positive determination in the process of S100 from the time when engine start is initiated in response to a start request for the internal combustion engine 10 until it is determined that engine start is completed. Note that start requests include an engine start request due to the automatic start described above and an engine start request due to the vehicle driver turning on the ignition switch. Furthermore, the control device 100 determines that engine start is completed when, for example, the engine rotation speed NE exceeds a specified determination value NEf.

[0035] If it is determined in the process of S100 that the engine is starting (S100: YES), the control device 100 determines whether the combustion of the air-fuel mixture is stable (S110). In the process of S110, the control device 100 determines that the combustion of the air-fuel mixture is stable if the engine rotation speed NE is equal to or greater than a specified determination value NEa. Note that the determination value NEa is a value smaller than the above-mentioned determination value NEf.

[0036] When it is determined in the process of S110 that the combustion of the air-fuel mixture is not stable (S110: NO), the control device 100 executes a first suppression process to suppress heating of the heater 55H by stopping the supply of electricity to the heater 55H (S120).

[0037] Next, the control device 100 executes a second suppression process to suppress the energization of the detection element of the air-fuel ratio sensor 55 by stopping the energization of the detection element (S130). On the other hand, when it is determined in the process of S110 that the combustion of the air-fuel mixture is stable (S110: YES), the control device 100 stops energizing the heater 55H (S140).

[0038] Next, the control device 100 executes energization of the detection element of the air-fuel ratio sensor 55 (S150). When the control device 100 has completed the process of S130 or the process of S150, or when a negative determination is made in the process of S100, the control device 100 temporarily ends the series of processes shown in FIG.

[0039] <Action and effect> The operation and effects of this embodiment will be described. (1-1) During the period from when the internal combustion engine 10 begins to start until the combustion of the air-fuel mixture stabilizes, the concentration of hydrogen gas flowing into the exhaust passage 90 may become higher than a predetermined value. Therefore, in this embodiment, the first suppression process is executed during the period from when the engine starts to when it is determined that the combustion of the air-fuel mixture stabilizes. Execution of this first suppression process suppresses heating of the heater 55H, thereby reducing the temperature of the air-fuel ratio sensor 55. Therefore, when the engine starts, it is possible to suppress the combustion of hydrogen gas in the sensor.

[0040] (1-2) When the detection element of the air-fuel ratio sensor 55 is energized, the detection element functions as a reactor. Therefore, when the detection element is energized, the ignition temperature of hydrogen gas tends to be lower than when the detection element is not energized. In this regard, in this embodiment, when the first suppression process is performed, the second suppression process, which stops the energization of the detection element, is also performed. Therefore, it is possible to lower the ignition temperature of hydrogen gas, which also makes it possible to suppress the combustion of hydrogen gas in the sensor.

[0041] (Second embodiment) Next, a second embodiment of a control device for an internal combustion engine will be described. In a hydrogen-fueled internal combustion engine 10, even when the engine is stopped, the concentration of hydrogen gas flowing into the exhaust passage 90 may exceed a predetermined combustible concentration. For example, when the engine is stopped, the piston 15 repeatedly moves up and down until the crankshaft 18 stops rotating. This movement of the piston 15 causes hydrogen gas in the blow-by gas accumulated in the crankcase 19 to flow into the intake passage via the blow-by treatment device described above. The hydrogen gas that flows into the intake passage then flows into the exhaust passage 90 without being burned in the combustion chamber 17. Furthermore, the hydrogen gas in the blow-by gas accumulated in the crankcase 19 flows into the combustion chamber 17 through the gap between the cylinder 16 and the piston 15 due to the up and down movement of the piston 15. This hydrogen gas that flows into the combustion chamber 17 then flows into the exhaust passage 90 without being burned in the combustion chamber 17. Therefore, even when the engine is stopped, the concentration of hydrogen gas flowing into the exhaust passage 90 may exceed a predetermined value. If the heater 55H of the air-fuel ratio sensor 55 is heated under such a condition that the concentration of hydrogen gas is higher than a predetermined value, there is a risk that unburned hydrogen gas will be burned inside the air-fuel ratio sensor 55.

[0042] Therefore, the time when the operation of the internal combustion engine 10 is stopped is set as a specified condition under which the concentration of hydrogen gas flowing into the exhaust passage 90 may become equal to or greater than a predetermined value. When this specified condition is met, the control device 100 executes a suppression process to suppress heating of the heater 55H.

[0043] <Suppression Processing of This Embodiment> A processing procedure for executing the suppression processing in this embodiment is shown in Fig. 3. The processing shown in Fig. 3 is realized by the control device 100 repeatedly executing it at predetermined intervals.

[0044] 3, the control device 100 first determines whether it is time to stop the operation of the internal combustion engine 10, more specifically, whether there is a stop request to stop the operation of the internal combustion engine 10 (S200). The stop request may be a request to stop operation due to the automatic stop described above, or a request to stop operation due to the vehicle driver turning off the ignition switch.

[0045] If there is a stop request (S200: YES), the control device 100 executes a first suppression process to suppress heating of the heater 55H by stopping the supply of power to the heater 55H (S2100).

[0046] Next, the control device 100 executes a second suppression process to suppress the energization of the detection element of the air-fuel ratio sensor 55 by stopping the energization of the detection element (S220). Next, the control device 100 determines whether the sensor temperature THs is equal to or lower than a reference value THsref (S230). The sensor temperature THs is the temperature of the air-fuel ratio sensor 55. The control device 100 calculates the sensor temperature THs based on, for example, the resistance value of the air-fuel ratio sensor 55 or the elapsed time since the heater 55H was turned off. The sensor temperature THs may also be measured. The reference value THsref is a predetermined value, and an example is the lowest temperature at which hydrogen gas may ignite.

[0047] When it is determined that the sensor temperature THs is equal to or lower than the reference value THsref (S230: YES), the control device 100 executes a shutdown of the internal combustion engine 10 (S240). In the processing of S240, the control device 100 executes a shutdown of the internal combustion engine 10 by stopping the supply of electricity to the spark plugs and stopping the fuel injection of each of the injection valves 83, 84.

[0048] When the process of S240 is completed or when a negative determination is made in the process of S200 or the process of S230, the control device 100 temporarily ends the series of processes shown in FIG. <Action and effect> The operation and effects of this embodiment will be described.

[0049] (2-1) When the operation of the internal combustion engine 10 is stopped, the concentration of hydrogen gas flowing into the exhaust passage 90 may become higher than a predetermined value. Therefore, in this embodiment, when there is a request to stop the operation of the internal combustion engine 10, the first suppression process is executed until it is determined that the sensor temperature THs is equal to or lower than the reference value THsref. Execution of this first suppression process suppresses heating of the heater 55H, thereby decreasing the temperature of the air-fuel ratio sensor 55. Therefore, when the engine is stopped, it is possible to suppress combustion of hydrogen gas in the sensor.

[0050] (2-2) Even if a stop request is made, the stop of the internal combustion engine 10 is delayed until the sensor temperature THs becomes equal to or lower than the reference value THsref. Therefore, the inflow of hydrogen gas into the exhaust passage 90 due to the stop of the operation occurs only after the combustion of hydrogen gas in the sensor is suppressed. Therefore, this also makes it possible to suppress the combustion of hydrogen gas in the sensor.

[0051] (2-3) When the detection element of the air-fuel ratio sensor 55 is energized, the detection element functions as a reactor. Therefore, when the detection element is energized, the ignition temperature of hydrogen gas tends to be lower than when the detection element is not energized. In this regard, in this embodiment, when the first suppression process is performed, the second suppression process, which stops the energization of the detection element, is also performed. Therefore, it is possible to lower the ignition temperature of hydrogen gas, which also makes it possible to suppress the combustion of hydrogen gas in the sensor.

[0052] <Example of change> The above-described embodiments can be modified as follows: The embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0053] In the process of S110 in the first embodiment, whether or not the combustion of the air-fuel mixture is stable is determined based on the engine rotation speed NE, but the determination may be made by other methods. For example, it may be determined that the combustion of the air-fuel mixture is stable when the intake air amount GA is equal to or greater than a threshold value GAref. When the engine speed NE is low, the flow velocity of the intake air flowing into the combustion chamber 17 is slower than when the engine speed NE is high, which tends to make the mixture less well mixed and result in unstable combustion. Therefore, even with the same intake air amount GA, the lower the engine speed NE, the more likely the combustion of the air-fuel mixture is to become unstable. Therefore, if the threshold value GAref is variably set so that the value of the threshold value GAref increases as the engine speed NE decreases, the accuracy of determining whether the combustion of the air-fuel mixture is stable can be improved.

[0054] Alternatively, for example, a fluctuation amount ΔNE of the engine rotation speed NE may be calculated. If the calculated fluctuation amount ΔNE is equal to or greater than a threshold value ΔNEref, it may be determined that the combustion of the air-fuel mixture is stable. Note that even in this case, if the threshold value ΔNEref is variably set so that the lower the engine rotation speed NE, the larger the value of the threshold value ΔNEref becomes, the more accurately it can be determined whether the combustion of the air-fuel mixture is stable.

[0055] In the second embodiment, the internal combustion engine 10 is stopped after the sensor temperature THs becomes equal to or lower than the reference value THsref. Alternatively, if there is a stop request, the internal combustion engine 10 may be stopped and the first suppression process and the second suppression process described above may be executed. Even in this case, it is possible to obtain advantageous effects other than those described in (2-2) above.

[0056] In each embodiment, the second suppression process may be omitted. In the first suppression process described above, the heater 55H is deenergized. Alternatively, the first suppression process may be a process in which the heater 55H is energized while the amount of power supplied to the heater 55H is reduced compared to when the first suppression process is not being executed. In this case, the heating of the heater 55H can be suppressed by executing the first suppression process.

[0057] In the second suppression process described above, the supply of electricity to the detection element is stopped. Alternatively, the second suppression process may be a process in which the supply of electricity to the detection element is reduced compared to when the second suppression process is not executed, while the detection element is still energized. In this case, too, the supply of electricity to the detection element can be suppressed by executing the second suppression process, thereby lowering the ignition temperature of hydrogen gas.

[0058] In the second embodiment, the internal combustion engine 10 is stopped after the sensor temperature THs becomes equal to or lower than the reference value THsref. Alternatively, if there is a stop request, the internal combustion engine 10 may be stopped and the first suppression process and the second suppression process described above may be executed.

[0059] The air-fuel ratio sensor 55 is exemplified as an example of a sensor that is provided in the exhaust passage 90, has a heater, and detects the air-fuel ratio. In addition, an oxygen sensor that can detect whether the air-fuel ratio is rich or lean may be provided.

[0060] Although a sensor with a heater for detecting the air-fuel ratio is provided upstream of the catalyst 95, a sensor with a heater for detecting the air-fuel ratio may also be provided downstream of the catalyst 95, and the suppression process described above may also be performed on this downstream sensor.

[0061] Although the PCV passage 35 is connected to the surge tank 60, the connection location may be changed as appropriate as long as it is located downstream of the throttle valve 28 in the intake passage. The internal combustion engine 10 may be provided with only one of the port injection valve 83 and the in-cylinder injection valve 84.

[0062] The internal combustion engine 10 does not necessarily need to include the supercharger 24 or the ejector 40 . The internal combustion engine 10 does not necessarily have to include the intake side variable valve timing mechanism 85 or the exhaust side variable valve timing mechanism 86.

[0063] The control device 100 may execute both the processes shown in Figure 2 and the processes shown in Figure 3. Alternatively, the control device 100 may execute only one of the processes shown in Figure 2 or 3. The control device is not limited to one equipped with a CPU 110 and memory 120 and executing software processing. For example, it may be equipped with a dedicated hardware circuit, such as an ASIC, that performs hardware processing on at least a portion of what was software processed in the above embodiments. That is, the control device may have any of the following configurations (a) to (c): (a) equipped with a processing device that executes all of the above processing in accordance with a program, and a program storage device, such as a ROM, that stores the program; (b) equipped with a processing device and program storage device that executes part of the above processing in accordance with a program, and a dedicated hardware circuit that executes the remaining processing; or (c) equipped with a dedicated hardware circuit that executes all of the above processing. Here, the software execution device equipped with a processing device and program storage device, and the dedicated hardware circuit may be one or any multiple number.

[0064] <Related technical ideas> The technical concepts that can be understood from the above embodiments and modifications will be described below. (Appendix 1) A control device applied to an internal combustion engine fueled by hydrogen, the internal combustion engine includes an exhaust passage; and a sensor that is provided in the exhaust passage and has a heater and detects an air-fuel ratio, A control device for an internal combustion engine that executes a suppression process to suppress heating of the heater when a specified condition is met under which the concentration of hydrogen gas flowing into the exhaust passage may become equal to or greater than a predetermined value.

[0065] (Appendix 2) the specified condition is when the internal combustion engine is started, 2. The control device for an internal combustion engine according to claim 1, wherein the suppression process is executed from the start of the internal combustion engine until combustion of the air-fuel mixture becomes stable.

[0066] (Appendix 3) the specified condition is when the operation of the internal combustion engine is stopped, 3. The control device for an internal combustion engine according to claim 1, wherein the suppression process is executed from when a request to stop operation of the internal combustion engine is made until the temperature of the sensor becomes equal to or lower than a predetermined temperature.

[0067] (Appendix 4) 4. The control device for an internal combustion engine according to claim 3, wherein a process is executed to delay stopping the operation of the internal combustion engine from when the request to stop the operation is made until the temperature of the sensor becomes equal to or lower than the predetermined temperature.

[0068] (Appendix 5) A control device for an internal combustion engine described in any one of Appendix 1 to Appendix 4, wherein when the suppression process is a first suppression process, a second suppression process is executed to suppress the flow of electricity to a detection element provided in the sensor when the first suppression process is executed. [Explanation of symbols]

[0069] 10...Internal combustion engine 19...Crankcase 20...Intake pipe 24...Turbocharger 28...Throttle valve 29...Intake manifold 32...Suction path 34...PCV valve 35…PCV passage 36...Bypass passage 37...Atmospheric intake passage 40...Ejector 55...Air-fuel ratio sensor 55H...Heater 60...Surge tank 81...Intake valve 82...Exhaust valve 83...Port injection valve 84...In-cylinder injection valve 90...Exhaust passage 92...Bypass passage 93...Wastegate valve (WGV) 100...Control device 110...Central processing unit (CPU) 120...Memory

Claims

1. A control device applied to an internal combustion engine fueled by hydrogen, the internal combustion engine includes an exhaust passage; and a sensor that is provided in the exhaust passage and has a heater and detects an air-fuel ratio, When a specified condition is met that indicates that the concentration of hydrogen gas flowing into the exhaust passage may be equal to or greater than a predetermined value, a suppression process is executed to suppress heating of the heater; the specified condition is when the operation of the internal combustion engine is stopped, The suppression process is a process that is executed from when a request to stop the operation of the internal combustion engine is made until the temperature of the sensor falls to or below a predetermined temperature. Control device for internal combustion engines.

2. A process for delaying the stop of the operation of the internal combustion engine is executed from the time when the operation stop request is made until the temperature of the sensor becomes equal to or lower than the predetermined temperature. The control device for an internal combustion engine according to claim 1.

3. A control device applied to an internal combustion engine fueled by hydrogen, the internal combustion engine includes an exhaust passage; and a sensor that is provided in the exhaust passage and has a heater and detects an air-fuel ratio, When a specified condition is met that indicates that the concentration of hydrogen gas flowing into the exhaust passage may be equal to or greater than a predetermined value, a suppression process is executed to suppress heating of the heater; When the suppression process is a first suppression process, a second suppression process is executed to suppress the supply of electricity to a detection element of the sensor when the first suppression process is executed. Control device for internal combustion engines.

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