JP2024119198A - Internal combustion engine - Google Patents

Abstract

[Problem] To provide an internal combustion engine that can avoid misfires caused by water adhering to the electrodes of a spark plug when starting operation, resulting in failure to start operation, and can also avoid excessive power consumption of the spark plug. [Solution] The internal combustion engine has a fuel injection valve, an ignition plug equipped with an electrode located in the combustion chamber, and a control unit that executes water removal control that increases the airflow generated near the electrode to remove water adhering to the electrode when the internal combustion engine starts and stops operating. [Selected Figure] Figure 4

Description

The present invention relates to an internal combustion engine. Specifically, the present invention relates to an internal combustion engine having a control unit that executes control to avoid the occurrence of misfires in spark plugs.

When an internal combustion engine is stopped, the temperature in the combustion chamber drops, resulting in condensation and water (water droplets) adhering to the electrodes of the spark plug. In addition, tiny water droplets may adhere to the electrodes while the internal combustion engine is operating. If water adheres to the electrodes of the spark plugs of an internal combustion engine, misfires may occur, which means that the fuel-containing mixture cannot be ignited. For example, if misfires occur continuously when the internal combustion engine is started, it may not be possible to start the engine.

For this reason, methods have been proposed to prevent spark plug misfires. Patent Document 1 discloses an ignition control device that adjusts discharge energy according to the humidity of the intake air introduced into the combustion chamber. With this ignition control device, the higher the humidity, the longer the time that electricity is applied to the ignition coil of the spark plug (i.e., the higher the discharge energy), and as a result, the spark plug is prevented from misfiring even when the humidity is high.

JP 2016-37880 A

However, the above-mentioned ignition control device requires an additional humidity detection unit (i.e., a humidity sensor) to detect the humidity of the intake air, which may complicate the configuration of the internal combustion engine. On the other hand, if the discharge energy of the spark plug is constantly increased without providing a temperature detection unit (i.e., regardless of humidity), the power consumption of the spark plug may become excessive.

The present invention was devised in light of these points, and aims to provide an internal combustion engine that can avoid excessive power consumption by the spark plug, while also avoiding the occurrence of a misfire caused by water adhering to the spark plug electrode, which causes the internal combustion engine to be unable to start operating.

To solve the above problems, the internal combustion engine according to the first aspect of the present invention has a fuel injection valve, an ignition plug with an electrode located in the combustion chamber, and a control unit that performs water removal control to increase the airflow generated near the electrode and remove water adhering to the electrode when the internal combustion engine starts and stops operating.

The second aspect of the present invention is an internal combustion engine according to the first aspect of the present invention, which has a tumble control valve that is controlled to increase the tumble flow generated in the combustion chamber, and the control unit controls the tumble control valve when the water removal control is performed to increase the airflow generated near the electrode.

The third aspect of the present invention is an internal combustion engine according to the first aspect of the present invention, in which the combustion chamber has a main combustion chamber and an auxiliary combustion chamber that communicates with the main combustion chamber and in which an air injection valve and the electrode are disposed, and the control unit causes the air injection valve to inject air into the auxiliary combustion chamber when the water removal control is performed.

The fourth aspect of the present invention is an internal combustion engine according to the first to third aspects, in which the control unit starts the water removal control before fuel injection by the fuel injection valve is started.

The fifth aspect of the present invention is an internal combustion engine according to the first to third aspects of the present invention, in which the fuel injection valve injects hydrogen or ammonia.

In the first invention, water adhering to the electrode of the spark plug when the internal combustion engine is started is removed by water removal control accompanied by an increase in airflow (e.g., an increase in the flow rate and/or flow velocity) generated near the electrode. Specifically, the water adhering to the electrode is blown away or vaporized. Therefore, water on the electrode generated by condensation of water vapor in the combustion chamber while the internal combustion engine is stopped is removed. In addition, water removal control is executed even when the internal combustion engine is stopped, and water (e.g., tiny water droplets) adhering to the electrode during the operation of the internal combustion engine is removed. Therefore, misfire of the spark plug due to water adhering to the electrode is avoided, and the possibility of avoiding failure of the internal combustion engine to start is increased.

In the second invention, water removal control is performed by increasing the airflow near the electrode using a tumble control valve. In other words, if an internal combustion engine is equipped with a tumble control valve, water removal control can be performed without providing a new sensor or actuator, etc., which increases the likelihood of avoiding spark plug misfires when starting the internal combustion engine.

In the third invention, water removal control is performed by increasing the airflow near the electrode using an air injection valve. This increases the likelihood of avoiding misfires in the spark plug when starting the internal combustion engine.

In the fourth invention, water adhering to the electrode is removed before fuel injection during operation of the internal combustion engine and ignition by the spark plug of the mixture containing the injected fuel begins. This water removal control without fuel injection is executed, for example, during cranking. In other words, water is removed from the electrode before the first ignition by the spark plug occurs when starting the internal combustion engine. As a result, there is an even higher possibility of avoiding misfire of the spark plug when starting the internal combustion engine.

The fifth invention is applied to an internal combustion engine fueled by hydrogen or ammonia. The combustion gas generated when a mixture containing hydrogen or ammonia is burned often has a higher water vapor concentration than when gasoline or diesel is used as fuel, increasing the possibility of water adhering to the electrodes. Even in such an internal combustion engine, water adhering to the electrodes can be removed by water removal control, and as a result, there is a high possibility that misfires in the spark plugs can be avoided when the internal combustion engine is started.

1 is a schematic diagram of an internal combustion engine according to a first embodiment. FIG. 2 is a diagram showing an airflow generated in a combustion chamber controlled by a tumble control valve of an internal combustion engine. 4 is a flowchart of an "engine control processing routine" executed by a control unit of the internal combustion engine. 4 is a flowchart of an "engine starting processing routine" executed by the control unit. 4 is a flowchart of an "engine stop processing routine" executed by the control unit. FIG. 5 is a schematic diagram of an internal combustion engine according to a second embodiment. 1 is a diagram showing that a main combustion chamber and an auxiliary combustion chamber of an internal combustion engine are connected to each other, and that an air injection valve is disposed in the auxiliary combustion chamber. 4 is a flowchart of an "engine control processing routine" executed by a control unit of the internal combustion engine. 4 is a flowchart of an "engine starting processing routine" executed by the control unit. 4 is a flowchart of an "engine stop processing routine" executed by the control unit.

First Embodiment
A first embodiment of the present invention will be described with reference to Figures 1 to 5. The same symbols (reference numbers) in the description refer to the same elements having the same functions, although they will not be described repeatedly. Figure 1 shows an internal combustion engine 1 according to the first embodiment. The internal combustion engine 1 is a multi-cylinder engine that uses hydrogen as fuel and is mounted as a driving force source in a vehicle (not shown, hereinafter also referred to as "mounted vehicle"), and Figure 1 shows only one cylinder. The internal combustion engine 1 includes a main body 10, an intake system 20, and an exhaust system 30, and is controlled by an ECU 41.

The main body 10 includes a cylinder block 11, a cylinder head 12, a piston 13, a connecting rod 14, a crankshaft 15, a fuel injection valve 16, an ignition plug 17, and a starter motor 18. Inside the main body 10, a combustion chamber 19 is formed by the cylinder block 11, the cylinder head 12, and the piston 13. The reciprocating motion of the piston 13 is transmitted to the crankshaft 15 via the connecting rod 14, causing the crankshaft 15 to rotate.

The fuel injection valve 16 injects hydrogen, which is a fuel, into the combustion chamber 19 in response to instructions from the ECU 41, and generates a mixture containing hydrogen and oxygen in the combustion chamber 19. High-pressure hydrogen is supplied to the fuel injection valve 16. A high-pressure hydrogen tank that stores the hydrogen supplied to the fuel injection valve 16 and a valve mechanism that adjusts the pressure of the hydrogen supplied to the fuel injection valve 16 are not shown in FIG. 1.

The spark plug 17 generates a spark in response to an instruction from the ECU 41, and ignites the mixture in the combustion chamber 19. The spark plug 17 includes a center electrode 17a and an outer electrode 17b (ground electrode) located in the combustion chamber 19 (see FIG. 2). The center electrode 17a is an electrode located in the center of the tip of the spark plug 17 body. The outer electrode 17b is an electrode electrically insulated from the center electrode 17a. The tip of the outer electrode 17b faces the center electrode 17a and is located at a predetermined distance from the center electrode 17a. The spark plug 17 boosts the power supplied from a storage battery (not shown) by an internal ignition coil (not shown) and applies it to the center electrode 17a and outer electrode 17b, thereby generating a spark.

The starter motor 18 (cell motor) generates torque to rotate the crankshaft 15 when starting the internal combustion engine 1. In other words, the starter motor 18 cranks the internal combustion engine 1. The starter motor 18 is supplied with power from a storage battery. When cranking, the starter motor 18 is connected to the crankshaft 15 via a gear mechanism (not shown) so that torque can be transmitted.

The intake system 20 includes an intake pipe 21, an intake port 22, an air cleaner 23, an intake valve 24, a throttle valve 25, a flow passage wall 26, and a tumble control valve 27. The air cleaner 23 is disposed near the upstream end of the intake pipe 21, and removes (filters) impurities contained in the intake air. The intake valve 24 is disposed in the cylinder head 12, and is driven by an intake camshaft (not shown) to open and close the communication between the intake port 22 and the combustion chamber 19. The intake valve 24 (and the exhaust valve 33) is a poppet valve that includes an elongated stem portion having a substantially cylindrical shape and a head portion that abuts against the combustion chamber 19 when closed.

The throttle valve 25 is opened and closed by a throttle valve actuator 25a that responds to instructions from the ECU 41. That is, the throttle valve actuator 25a adjusts the throttle valve opening TA, which is the opening of the throttle valve 25, thereby adjusting the amount of air taken into the combustion chamber 19.

The flow passage wall 26 is a flow passage dividing plate arranged in the intake pipe 21. The air flow (intake flow) flowing through the intake pipe 21 is divided into an upper flow passage 21a and a lower flow passage 21b in the section where the flow passage wall 26 is arranged. The tumble control valve 27 (tumble generator valve, hereinafter also referred to simply as the tumble valve 27) is a valve body (flap) that rotates together with a shaft 27a arranged at the upstream end of the flow passage wall 26 (see FIG. 2). The shaft 27a is rotated by a tumble control actuator 27b that responds to instructions from the ECU 41 (see FIG. 1).

Specifically, the ECU 41 controls the tumble control actuator 27b to adjust the rotation angle of the shaft 27a, thereby realizing either a state in which the tumble valve 27 closes the lower flow passage 21b (closed state) or a state in which the tumble valve 27 does not close the lower flow passage 21b (open state). In FIG. 2, the tumble valve 27 in the closed state is shown by a solid line, and the tumble valve 27 in the open state is shown by a dashed line. As described later, the ECU 41 closes the tumble valve 27 in order to generate a tumble flow in the combustion chamber 19 during the intake stroke (to increase the tumble flow in the combustion chamber 19).

The exhaust system 30 includes an EGR system, and specifically includes an exhaust pipe 31, an exhaust port 32, an exhaust valve 33, an EGR pipe 34, and an EGR valve 35. The exhaust valve 33 is disposed in the cylinder head 12, and is driven by an exhaust camshaft (not shown) to open and close the communication between the combustion chamber 19 and the exhaust port 32. An exhaust purification device that purifies the exhaust (combustion gas) discharged from the combustion chamber 19 is not shown in FIG. 1.

The EGR pipe 34 connects the exhaust pipe 31 and the intake pipe 21. The EGR valve 35 is disposed in the EGR pipe 34. The opening state of the EGR valve 35 changes between a predetermined fully open position (fully open state) and a fully closed position (fully closed state) in response to an instruction from the ECU 41, thereby adjusting the amount of EGR gas recirculated from the exhaust pipe 31 to the intake pipe 21.

The ECU 41 is an electronic control unit (control unit, control device) that includes a CPU, ROM, RAM, and EEPROM. The CPU reads data, performs numerical calculations, and outputs the results of calculations by sequentially executing a specified program. The ROM stores the programs executed by the CPU and maps (lookup tables), etc. The RAM temporarily stores data referenced by the CPU. The EEPROM stores data referenced by the CPU, and furthermore, retains the stored data even when the ECU 41 stops operating.

The ECU 41 is also connected to an intake air volume sensor 51, a crank angle sensor 52, an accelerator opening sensor 53, a vehicle speed sensor 54, and an ignition switch 55. The intake air volume sensor 51 outputs a signal that represents the intake air volume Ga, which is the mass flow rate of air (fresh air) introduced into the intake pipe 21.

The crank angle sensor 52 generates a pulse signal each time the crankshaft 15 rotates a certain angle. The ECU 41 obtains the engine speed NE of the internal combustion engine 1 based on the pulse signal. Furthermore, the ECU 41 obtains the crank angle CA of a specific cylinder of the internal combustion engine 1 based on the pulse from the crank angle sensor 52 and the pulse from a cam position sensor (not shown).

The accelerator opening sensor 53 outputs a signal representing an accelerator operation amount Ap, which is the operation amount (depression amount) of an accelerator pedal (not shown) of the vehicle. The vehicle speed sensor 54 outputs a signal representing a vehicle speed Vs, which is the traveling speed of the vehicle.

The ignition switch 55 is a push-type switch (button) that is operated (pressed) by the driver of the vehicle in which it is installed. The ECU 41 can detect the operation state of the ignition switch 55 (i.e., whether it is pressed or not). If the ignition switch 55 is pressed when the internal combustion engine 1 is not operating, the ECU 41 detects this operation as an "engine start request." If the ignition switch 55 is pressed while the internal combustion engine 1 is operating, the ECU 41 detects this operation as an "engine stop request."

The ECU 41 acquires the required torque Treq while the internal combustion engine 1 is operating (i.e., while the vehicle is traveling) and determines the throttle valve opening TA based on the required torque Treq. The required torque Treq is a value that correlates with the acceleration of the vehicle that is required (expected) by the driver. The throttle valve opening TA is determined so that the torque actually generated by the internal combustion engine 1 is equal to the required torque Treq. Generally, the greater the required torque Treq, the greater the throttle valve opening TA. The ECU 41 controls the throttle valve actuator 25a according to the determined throttle valve opening TA.

In addition, the ECU 41 determines the fuel injection amount Qn based on the intake air amount Ga so that the air-fuel ratio of the mixture in the combustion chamber 19 becomes a predetermined target air-fuel ratio Rn. When the crank angle CA in each cylinder of the internal combustion engine 1 reaches a predetermined fuel injection angle, the ECU 41 controls the fuel injection valve 16 of that cylinder (i.e., the combustion chamber 19) so that the amount of fuel injected is equal to the fuel injection amount Qn. When fuel is injected from the fuel injection valve 16 of a certain cylinder, the ECU 41 controls the spark plug 17 of that cylinder to ignite the mixture when the crank angle CA in that cylinder reaches a predetermined ignition angle.

Furthermore, when a predetermined "tumble valve closing condition" is met, the ECU 41 controls the tumble control actuator 27b so that the tumble valve 27 is closed. The tumble valve closing condition is met, for example, when the intake air amount Ga is smaller than a predetermined threshold value. If the tumble valve closing condition is not met, the ECU 41 controls the tumble control actuator 27b so that the tumble valve 27 is open.

(Water Removal Control)
When hydrogen and oxygen contained in the air-fuel mixture are combusted in the combustion chamber 19, water (specifically, water vapor) is generated. That is, water is contained in the combustion gas generated in the combustion chamber 19. The amount of water contained in the combustion gas is greater than that of an internal combustion engine (gasoline engine) that uses gasoline (i.e., a mixture of hydrocarbons) as fuel, for example.

Therefore, in the period from when the internal combustion engine 1 stops operating until it starts operating again, the possibility that the water vapor in the combustion chamber 19 will condense and water (e.g., water droplets) will adhere to the electrodes (center electrode 17a and/or outer electrode 17b) of the spark plug 17 is higher than in a gasoline engine. Furthermore, a small amount of water may also adhere to the electrodes of the spark plug 17 while the internal combustion engine 1 is operating.

If water is attached to the electrodes of the spark plug 17, even if a voltage is applied to the spark plug 17, a spark will not be generated between the center electrode 17a and the outer electrode 17b, and the mixture in the combustion chamber 19 will likely not be ignited. In other words, the spark plug 17 is more likely to misfire. In particular, if the amount of water attached to the electrodes of the spark plug 17 increases due to condensation in the combustion chamber 19 while the internal combustion engine 1 is stopped, the spark plug 17 will likely misfire continuously, and the internal combustion engine 1 will likely be unable to start operating.

The ECU 41 therefore executes "water removal control" to remove water adhering to the electrode of the spark plug 17 when the internal combustion engine 1 starts and stops operating. The water removal control is a control that increases the airflow near the electrode of the spark plug 17 in the combustion chamber 19 compared to when the water removal control is not executed. In other words, when the water removal control is executed, the flow velocity and/or volume of the air (intake air) near the electrode of the spark plug 17 increases. When the water removal control is executed, the water adhering to the electrode of the spark plug 17 is blown away or vaporized, reducing the possibility of misfire of the spark plug 17.

(Water removal control - start of operation)
A description will now be given of the water removal control that is executed when the internal combustion engine 1 starts operating. When the ignition switch 55 is pressed while the internal combustion engine 1 is stopped (i.e., when the ECU 41 detects an engine start request), the ECU 41 controls the tumble valve 27 to a closed state and starts cranking (i.e., generation of torque by the starter motor 18).

Here, the ECU 41 does not cause the fuel injection valve 16 to inject fuel until a predetermined period of time has elapsed. Specifically, after cranking is started, during the period until the number of revolutions of the crankshaft 15 reaches a predetermined start control rotation speed Ca1, the ECU 41 sets the fuel injection amount Qn to "0."

When the rotation speed of the crankshaft 15 reaches the starting control rotation speed Ca1, the ECU 41 starts fuel injection by the fuel injection valve 16 and ignition of the mixture by the spark plug 17. When the mixture is ignited and the internal combustion engine 1 starts operating, the ECU 41 ends cranking.

When the tumble valve 27 is controlled to a closed state during cranking (i.e., when the lower flow passage 21b is closed), a tumble flow is generated in the combustion chamber 19, as shown by the solid arrow in FIG. 2. Specifically, the air (intake air) that flows into the combustion chamber 19 through the upper flow passage 21a is urged by the umbrella part of the intake valve 24 toward the vicinity of the electrode of the ignition plug 17, and then flows along the inner wall surface of the combustion chamber 19 to form a tumble flow. More specifically, by controlling the tumble valve 27 to a closed state, the amount of air that flows near the electrode of the ignition plug 17 and further forms a tumble flow in the combustion chamber 19 increases. Note that the symbols for the upper flow passage 21a (the flow passage above the flow passage wall 26) and the lower flow passage 21b (the flow passage below the flow passage wall 26) are omitted in FIG. 2.

If the tumble valve 27 is controlled to be open during cranking, as shown by the dashed arrow in Figure 2, the air flowing into the combustion chamber 19 via the upper flow passage 21a collides with the air flowing into the combustion chamber 19 via the lower flow passage 21b, generating turbulence in the combustion chamber 19. In this case, the amount of air flowing through the upper flow passage 21a is reduced compared to when the tumble valve 27 is closed.

In other words, when the tumble valve 27 is controlled to a closed state during cranking, the airflow generated near the electrode of the spark plug 17 increases compared to when the tumble valve 27 is controlled to an open state. Therefore, even if water adheres to the electrode of the spark plug 17, the water is more likely to be removed by the tumble flow. As a result, when the internal combustion engine 1 starts operating, the water adhered to the electrode is less likely to prevent the spark plug 17 from generating a spark (i.e., a misfire occurs) when fuel injection is started by the fuel injection valve 16.

(Water removal control - when not in operation)
Next, a description will be given of the water removal control that is executed when the operation of the internal combustion engine 1 is stopped. When the ignition switch 55 is pressed while the internal combustion engine 1 is operating (i.e., when the ECU 41 detects an engine stop request), the ECU 41 controls the tumble valve 27 to a closed state and maintains the internal combustion engine 1 in an idle state until a predetermined period of time has elapsed. Specifically, after detecting the engine stop request, the ECU 41 stops the operation of the internal combustion engine 1 when the number of revolutions of the crankshaft 15 reaches a predetermined stop control rotation speed Cd1.

In other words, the state in which the air flow near the electrode of the spark plug 17 is increased because the tumble valve 27 is closed is maintained until a predetermined period of time has elapsed. Therefore, even if a small amount of water adheres to the electrode of the spark plug 17 while the internal combustion engine 1 is in operation, the tumble valve 27 is controlled to be closed, which increases the likelihood that the adhered water will be removed by the increased air flow near the electrode.

(Specific operation)
3 to 5, the specific operation of the ECU 41 will be described. The CPU of the ECU 41 (hereinafter, simply referred to as the "CPU") executes an "engine control processing routine" shown in the flowchart of FIG. 3 at predetermined time intervals.

In the routines of Figures 3 to 5, the values of the engine operation flag Xo, the start control flag Xa, and the stop control flag Xd are set and referenced. Each of these flags is set to "0" by the processing of an initial routine (not shown) that is executed when the ECU 41 starts operating (i.e., when the internal combustion engine 1 is not yet operating).

When water removal control is initiated at the start of the internal combustion engine 1, the start control flag Xa is set to "1". When the internal combustion engine 1 subsequently starts operating, the start control flag Xa is set to "0" and the engine operation flag Xo is set to "1". When water removal control is initiated at the stop of the internal combustion engine 1, the stop control flag Xd is set to "1". When the internal combustion engine 1 subsequently stops operating, both the engine operation flag Xo and the stop control flag Xd are set to "0".

When the appropriate timing arrives, the CPU starts processing from step 300 in FIG. 3 and proceeds to step 305, where it determines whether the engine operation flag Xo is "1".

(Specific operation - when operation begins)
3 is executed for the first time after the ignition switch 55 is pressed while the internal combustion engine 1 is stopped. In this case, the engine operation flag Xo is "0", so the CPU determines "No" in step 305 and proceeds to step 310, where it determines whether the start control flag Xa is "0".

According to this assumption, the start control flag Xa has not yet been set to "1", so the CPU judges "Yes" in step 310 and proceeds to step 315 to determine whether an engine start request has been detected. In other words, the CPU determines whether the ignition switch 55 has been pressed while the internal combustion engine 1 is stopped.

According to this assumption, since the ignition switch 55 is pressed, the CPU judges "Yes" in step 315 and proceeds to step 320, where it sets the start control flag Xa to "1." The CPU then proceeds to step 325, where it executes the "engine start processing routine" shown in the flowchart of FIG. 4.

Specifically, the CPU proceeds from step 400 to step 405 in FIG. 4 to determine whether or not it is immediately after the start control flag Xa is set to "1." In other words, the CPU determines whether or not the routine in FIG. 4 is being executed for the first time after the start control flag Xa is set to "1" by the processing of step 320 in FIG. 3.

According to this assumption, since the start control flag Xa has just become "1", the CPU judges "Yes" in step 405 and proceeds to step 410 to execute the closing control of the tumble valve 27. Specifically, if the tumble valve 27 is in an open state, the CPU controls the tumble control actuator 27b so that the tumble valve 27 is in a closed state. If the tumble valve 27 is in a closed state, the CPU maintains that state.

Then, the CPU proceeds to step 415 and starts cranking. Specifically, the CPU connects the starter motor 18 to the crankshaft 15 so that torque can be transmitted, and starts the operation of the starter motor 18, thereby rotating the crankshaft 15. At this time, the transmission of torque from the internal combustion engine 1 to the drive wheels (not shown) of the vehicle is interrupted by the operation of the clutch mechanism (not shown) of the vehicle.

The CPU then proceeds to step 420, where it determines whether the number of revolutions of the crankshaft 15 has reached the start control revolutions Ca1 after cranking has started. According to this assumption, since cranking by the starter motor 18 has just started, the number of revolutions of the crankshaft 15 has not yet reached the start control revolutions Ca1. Therefore, the CPU determines "No" in step 420 and proceeds to step 430, where it sets the fuel injection amount Qn to "0". In other words, fuel injection by the fuel injection valve 16 has not started at this point.

Then, the CPU proceeds to step 495, ends the processing of the routine in FIG. 4, and returns to the processing of the routine in FIG. 3. Specifically, the CPU proceeds to step 395 in FIG. 3, and temporarily ends the processing of the routine in FIG. 3.

Next, when the processing of the routine in FIG. 3 is started, since the engine operation flag Xo is "0" and the start control flag Xa is "1", the CPU proceeds from step 305 to step 310, determines "No" at step 310, and proceeds to step 325. That is, the CPU starts the processing of the routine in FIG. 4.

In this case, since it is not immediately after the start control flag Xa becomes "1", the CPU judges "No" in step 405 and proceeds directly to step 420. At this point, the number of revolutions of the crankshaft 15 after cranking has started has not yet reached the start control revolutions Ca1, so the CPU judges "No" in step 420. In other words, fuel injection by the fuel injection valve 16 has not started.

Then, when the number of revolutions of the crankshaft 15 after the start of cranking reaches the starting control revolution number Ca1 and the routine of FIG. 3 is executed for the first time, the CPU judges "Yes" in step 420 of FIG. 4 and proceeds to step 425. In step 425, the CPU sets the fuel injection amount Qn to a predetermined starting injection amount Qc. The starting injection amount Qc is a fuel injection amount adapted to allow the internal combustion engine 1 to quickly start operating by cranking.

When the fuel injection amount Qn is set to a value greater than "0", the CPU executes a routine not shown to inject fuel from the fuel injection valve 16 and ignite the fuel-containing mixture from the spark plug 17. Specifically, when the crank angle CA of one of the multiple cylinders (combustion chambers 19) of the internal combustion engine 1 reaches the fuel injection angle, the CPU injects fuel equal to the fuel injection amount Qn from the fuel injection valve 16 of that cylinder. After that, when the crank angle CA of that cylinder reaches the ignition angle, the CPU generates a spark in the spark plug 17 of that cylinder to ignite the fuel-containing mixture.

Then, the CPU proceeds to step 435 and determines whether the internal combustion engine 1 has started. That is, the CPU determines whether the mixture in the combustion chamber 19 has been ignited and the internal combustion engine 1 is generating torque to rotate the crankshaft 15. Specifically, the CPU determines whether the engine rotation speed NE is greater than the rotation speed when the crankshaft 15 is being rotated by the starter motor 18 (i.e., when the internal combustion engine 1 is not generating torque).

According to this assumption, since fuel injection by the fuel injection valve 16 has just started, the internal combustion engine 1 has not yet started. Therefore, the CPU determines "No" in step 435 and proceeds directly to step 395.

Then, when the routine in FIG. 3 is executed for the first time after the internal combustion engine 1 starts, the CPU judges "Yes" in step 435 and sequentially executes the processes in steps 440 to 450 described below. Next, the CPU proceeds to step 495.

Step 440: The CPU stops cranking. Specifically, the CPU interrupts torque transmission from the starter motor 18 to the crankshaft 15 and stops the operation of the starter motor 18 (i.e., the generation of torque).
Step 445: The CPU sets the start control flag Xa to “0”.
Step 450: The CPU sets the engine operation flag Xo to “1”.
In this case, the water removal control ends.

Next, when the processing of the routine in FIG. 3 is started, since the engine operation flag Xo is "1", the CPU judges "Yes" in step 305 and proceeds to step 330 to determine whether the stop control flag Xd is "0".

According to this assumption, since the stop control flag Xd is "0", the CPU judges "Yes" in step 330 and proceeds to step 335 to judge whether an engine stop request has been detected. In other words, the CPU judges whether the ignition switch 55 has been pressed while the internal combustion engine 1 is operating.

According to this assumption, the internal combustion engine 1 has just started operating, so the ignition switch 55 has not been pressed. Therefore, the CPU determines "No" in step 335 and proceeds to step 350.

In step 350, the CPU adjusts the throttle valve opening TA based on the required torque Treq. Specifically, the CPU obtains the required torque Treq by applying the accelerator operation amount Ap, the vehicle speed Vs, etc. to a pre-adapted map. In addition, the CPU obtains (determines) a target value for the throttle valve opening TA by applying the required torque Treq to the pre-adapted map. The CPU controls the throttle valve actuator 25a so that the actual throttle valve opening TA is equal to the obtained target value for the throttle valve opening TA.

Then, the CPU proceeds to step 355 and determines the fuel injection amount Qn based on the target air-fuel ratio Rn. Specifically, the CPU determines the fuel injection amount Qn according to the intake air amount Ga so that the air-fuel ratio of the mixture in the combustion chamber 19 becomes the target air-fuel ratio Rn.

The CPU then proceeds to step 360 to determine whether the above-mentioned tumble valve closing condition is satisfied. If the tumble valve closing condition is satisfied, the CPU judges "Yes" at step 360 and proceeds to step 365, where it executes the same process as step 410 in FIG. 4 to perform the closing control of the tumble valve 27. Next, the CPU proceeds to step 395.

On the other hand, if the tumble valve closing condition is not satisfied, the CPU determines "No" in step 360 and proceeds to step 370, where it executes the opening control of the tumble valve 27. Specifically, if the tumble valve 27 is in a closed state, the CPU controls the tumble control actuator 27b so that the tumble valve 27 is in an open state. If the tumble valve 27 is in an open state, the CPU maintains that state. Next, the CPU proceeds to step 395.

(Specific operation - when operation stops)
3 is executed for the first time after the ignition switch 55 is pressed while the internal combustion engine 1 is in operation. In this case, the engine operation flag Xo is "1" and the stop control flag Xd is "0", so the CPU proceeds from step 305 to step 330, determines "Yes" in step 330, and proceeds to step 335.

According to this assumption, since the ignition switch 55 is pressed (i.e., since an engine stop request is detected), the CPU judges "Yes" in step 335 and proceeds to step 340, where it sets the stop control flag Xd to "1." Next, the CPU proceeds to step 345, where it executes the "engine stop processing routine" shown in the flowchart of FIG. 5.

Specifically, the CPU proceeds from step 500 to step 505 in FIG. 5 and determines whether the stop control flag Xd has just become "1". Specifically, the CPU determines whether the routine in FIG. 5 is being executed for the first time after the stop control flag Xd is set to "1" by the processing of step 340 in FIG. 3.

According to this assumption, since the stop control flag Xd has just become "1", the CPU judges "Yes" in step 505 and proceeds to step 410, where it executes the same process as step 410 in FIG. 4 to control the closing side of the tumble valve 27. Furthermore, the CPU proceeds to step 515, where, after detecting the engine stop request, it determines whether the rotation speed of the crankshaft 15 has reached the stop control rotation speed Cd1.

According to this assumption, since it is immediately after an engine stop request is detected (i.e., immediately after the ignition switch 55 is pressed), the rotation speed of the crankshaft 15 has not yet reached the stop control rotation speed Cd1. Therefore, the CPU judges "No" in step 515 and proceeds to step 520, where it sets the fuel injection amount Qn to a predetermined idle injection amount Qi. The idle injection amount Qi is a fuel injection amount adapted so that the engine rotation speed NE becomes the predetermined idle rotation speed. That is, in this case, the internal combustion engine 1 is in an idle state. At this time, the transmission of torque from the internal combustion engine 1 to the drive wheels is interrupted by the operation of the clutch mechanism of the vehicle on which it is mounted.

Then, the CPU proceeds to step 595, ends the processing of the routine in FIG. 5, and returns to the processing of the routine in FIG. 3. Specifically, the CPU proceeds to step 395 in FIG. 3, and temporarily ends the processing of the routine in FIG. 3.

Next, when the processing of the routine in FIG. 3 is started, since the engine operation flag Xo is "1" and the stop control flag Xd is "1", the CPU judges "No" in step 330 and proceeds to step 345. In other words, the CPU starts the processing of the routine in FIG. 5.

In this case, since the stop control flag Xd has not immediately become "1", the CPU determines "No" in step 505 and proceeds directly to step 515. At this point, the number of revolutions of the crankshaft 15 after the engine stop request is detected has not yet reached the stop control revolutions Cd1, so the CPU determines "No" in step 515. In other words, the internal combustion engine 1 is maintained in an idle state.

Then, when the number of revolutions of the crankshaft 15 after the engine stop request is detected reaches the stop control revolution number Cd1 and the routine in FIG. 3 is executed for the first time, the CPU judges "Yes" in step 515 in FIG. 5 and sequentially executes the processes in steps 525 to 535 described below. Next, the CPU proceeds to step 595.

Step 525: The CPU sets the fuel injection amount Qn to “0.” That is, the CPU stops the operation of the internal combustion engine 1.
Step 530: The CPU sets the stop control flag Xd to “0”.
Step 535: The CPU sets the engine operation flag Xo to “0”.

(Specific operation - other processing)
If the internal combustion engine 1 is not operating (i.e., the engine operation flag Xo and the start control flag Xa are both "0") and an engine start request has not been detected, the CPU determines "No" in step 315 and proceeds to step 395. That is, the CPU does not control the internal combustion engine 1. In other words, the ECU 41 is in a standby state until the ignition switch 55 is pressed.

Second Embodiment
The second embodiment will be described with reference to Figures 6 to 10. The internal combustion engine 1 according to the first embodiment is provided with a tumble valve 27 that controls the airflow generated in the combustion chamber 19, and the ECU 41 controls the tumble valve 27 of the internal combustion engine 1 when water removal control is being executed. Instead, the internal combustion engine 2 according to the second embodiment is provided with an air injection valve 67 that injects air into the auxiliary combustion chamber 62, and the ECU 42 controls the air injection valve 67 when water removal control is being executed. The following description will focus on this difference.

As shown in FIG. 6, the internal combustion engine 2 has a main combustion chamber 61 (main chamber) and an auxiliary combustion chamber 62 (pre-chamber). The auxiliary combustion chamber 62 is a space formed in the cylinder head 12a of the internal combustion engine 2. The main combustion chamber 61 and the auxiliary combustion chamber 62 are separated by a dividing plate 63 having multiple through holes formed therein. In other words, the main combustion chamber 61 and the auxiliary combustion chamber 62 are in communication with each other via the through holes formed in the dividing plate 63.

When the intake valve 24 is open, the main combustion chamber 61 communicates with the intake pipe 21 via the intake port 22. When the exhaust valve 33 is open, the main combustion chamber 61 communicates with the exhaust pipe 31 via the exhaust port 32. A main fuel injection valve 64 is disposed in the main combustion chamber 61. The main fuel injection valve 64 injects fuel (i.e., hydrogen) into the main combustion chamber 61 in response to an instruction from the ECU 42 according to the second embodiment.

The auxiliary combustion chamber 62 is provided with a secondary fuel injection valve 65, a spark plug 66, and an air injection valve 67. The secondary fuel injection valve 65 injects fuel (hydrogen) into the auxiliary combustion chamber 62 in response to instructions from the ECU 42. The spark plug 66 ignites the mixture in the auxiliary combustion chamber 62 in response to instructions from the ECU 42. The spark plug 66 has a center electrode 66a and an outer electrode 66b (see Figure 7).

As shown by the solid arrow in FIG. 7, the air injection valve 67 injects air into the auxiliary combustion chamber 62 in response to an instruction from the ECU 42. More specifically, air is supplied to the air injection valve 67 via an air supply pipe 68 (see FIG. 6). One end of the air supply pipe 68 is connected to a section of the intake pipe 21 between the air cleaner 23 and the junction with the EGR pipe 34. The air injection valve 67 has a built-in pressure pump (not shown) and pressurizes the air supplied from the air supply pipe 68 and injects it into the auxiliary combustion chamber 62.

During operation of the internal combustion engine 2, the ECU 42 causes the main fuel injection valve 64 to inject fuel so that the air-fuel ratio of the mixture in the main combustion chamber 61 becomes a predetermined target main air-fuel ratio Rm. In addition, the ECU 42 causes the secondary fuel injection valve 65 to inject fuel so that the air-fuel ratio of the mixture in the secondary combustion chamber 62 becomes a predetermined target secondary air-fuel ratio Rs.

When the ECU 42 generates a spark between the electrodes of the spark plug 66 to ignite the air-fuel mixture in the auxiliary combustion chamber 62, the combustion gas (i.e., high-temperature, high-pressure gas) generated in the auxiliary combustion chamber 62 flows into the main combustion chamber 61 through the through-holes in the dividing plate 63, as shown by the dashed arrow in FIG. 7. As a result, the combustion gas flowing from the auxiliary combustion chamber 62 into the main combustion chamber 61 ignites the air-fuel mixture in the main combustion chamber 61, and the mixture in the main combustion chamber 61 burns.

The target main air-fuel ratio Rm is greater than the target secondary air-fuel ratio Rs (i.e., Rm>Rs). In other words, the mixture in the main combustion chamber 61 has a lower fuel concentration than the mixture in the secondary combustion chamber 62. Therefore, even if a spark is generated in the spark plug disposed in the main combustion chamber 61, the mixture in the main combustion chamber 61 may not be ignited and may not burn. Alternatively, even if the mixture in the main combustion chamber 61 is successfully ignited, the combustion speed may be slow due to the low fuel concentration, and as a result, not all of the fuel injected from the main fuel injection valve 64 may be burned.

Therefore, in the internal combustion engine 2, the combustion gas generated by the combustion of the mixture in the auxiliary combustion chamber 62 is used to ignite the mixture in the main combustion chamber 61, which has a low fuel concentration, and increase the combustion speed. Therefore, the internal combustion engine 2 can achieve high energy efficiency (i.e., good fuel economy) through so-called super lean combustion.

In addition, the air (fresh air) injected from the air injection valve 67 can efficiently discharge (i.e., scavenge) the combustion gas generated in the auxiliary combustion chamber 62 to the main combustion chamber 61 (and further to the exhaust pipe 31). In this embodiment, during operation of the internal combustion engine 2, the ECU 42 injects an amount of air equal to a predetermined scavenging injection amount Aw into the air injection valve 67 during the exhaust stroke of each cylinder of the internal combustion engine 2. As a result, the combustion gas generated in both the main combustion chamber 61 and the auxiliary combustion chamber 62 can be discharged to the exhaust pipe 31.

(Water Removal Control)
The water removal control executed when the internal combustion engine 2 starts to operate will be described. When the ignition switch 55 is pressed while the internal combustion engine 2 is stopped, the ECU 42 controls the starter motor 18 to start cranking and causes the air injection valve 67 to inject air. Specifically, the ECU 42 causes the air injection valve 67 to inject an amount of air equal to a predetermined water removal injection amount Ab during the exhaust stroke of each cylinder of the internal combustion engine 2 (i.e., when the exhaust valve 33 is open). That is, fuel injection is not performed by the main fuel injection valve 64 and the secondary fuel injection valve 65, and air injection is performed by the air injection valve 67.

In this embodiment, the water removal injection amount Ab is greater than the scavenging injection amount Aw (i.e., Ab>Aw). In other words, when the water removal control is being performed, the amount of air injected from the air injection valve 67 increases compared to when the internal combustion engine 2 is in operation (i.e., when the water removal control is not being performed), and as a result, the airflow generated near the electrode of the spark plug 66 increases.

After cranking has started, when the number of revolutions of the crankshaft 15 reaches a predetermined start control rotation speed Ca2, the ECU 42 starts fuel injection from the main fuel injection valve 64 and the secondary fuel injection valve 65. After fuel is injected from the main fuel injection valve 64 and the secondary fuel injection valve 65 of a certain cylinder, when the crank angle CA of that cylinder reaches the ignition angle, the ECU 42 controls the spark plug 66 (of that cylinder) to ignite the mixture. As a result, the internal combustion engine 2 starts operating.

Next, the water removal control executed when the internal combustion engine 2 stops operating will be described. When the ignition switch 55 is pressed while the internal combustion engine 2 is operating, the ECU 42 maintains the internal combustion engine 1 in an idle state until a predetermined period of time has elapsed. At this time, the ECU 42 injects an amount of air equal to the water removal injection amount Ab into the air injection valve 67 during the exhaust stroke of each cylinder of the internal combustion engine 2. The ECU 42 stops the operation of the internal combustion engine 2 when the number of revolutions of the crankshaft 15 reaches a predetermined stop control rotation speed Cd2 after the ignition switch 55 is pressed.

(Specific operation)
The specific operation of the ECU 42 will be described with reference to Figures 8 to 10. The CPU of the ECU 41 (hereinafter also simply referred to as "CPU") executes an "engine control processing routine" shown in the flowchart of Figure 8 at predetermined time intervals. Note that steps shown in the flowcharts of Figures 8 to 10 that execute the same processes as the steps shown in Figures 3 to 5 are given the same step numbers as those in Figures 3 to 5.

When the appropriate timing arrives, the CPU starts processing from step 800 in FIG. 8 and proceeds to step 305. If the engine operation flag Xo is "1" (i.e., the internal combustion engine 2 is operating) and the ignition switch 55 is not pressed, the CPU proceeds from step 305 to step 350 via step 330 and step 335.

Then, the CPU sequentially executes the processes of steps 855 to 865 described below. In addition, the CPU proceeds to step 995 to end the process of the routine in FIG. 9, and then temporarily ends the process of the routine in FIG. 8.

Step 855: The CPU determines the main fuel injection amount Qm based on the target main air-fuel ratio Rm. Specifically, the CPU determines the main fuel injection amount Qm according to the intake air amount Ga so that the air-fuel ratio of the mixture in the main combustion chamber 61 becomes the target main air-fuel ratio Rm.
Step 860: Similar to the process of step 855, the CPU determines the secondary fuel injection amount Qs based on the target secondary air-fuel ratio Rs.
Step 865: The CPU sets the air injection amount As to the scavenging injection amount Aw.

(Specific operation - when operation begins)
When the CPU determines "No" in step 310, or when the CPU ends the process of step 320, the CPU proceeds to step 825 and executes the "engine starting process routine" shown in the flowchart of Fig. 9. That is, during the period in which the start control flag Xa is "1", the CPU repeatedly executes the routine of Fig. 9.

More specifically, the CPU proceeds from step 900 in FIG. 9 to step 405 to determine whether or not it is immediately after the start control flag Xa becomes "1". If it is immediately after the start control flag Xa becomes "1" (i.e., immediately after an engine start request is detected), the CPU determines "Yes" in step 405 and proceeds to step 415 to start cranking, and then proceeds to step 920. On the other hand, if it is not immediately after the start control flag Xa becomes "1", the CPU determines "No" in step 405 and proceeds directly to step 920.

In step 920, the CPU determines whether the number of revolutions of the crankshaft 15 has reached the start control revolutions Ca2 after cranking has started. If the number of revolutions of the crankshaft 15 has not yet reached the start control revolutions Ca2 after cranking has started, the CPU determines "No" in step 920 and sequentially executes the processing of steps 955 to 965 described below. Next, the CPU proceeds to step 995 to end the processing of the routine in FIG. 9, and then ends the processing of the routine in FIG. 8.

Step 955: The CPU sets the main fuel injection amount Qm to “0”.
Step 960: The CPU sets the secondary fuel injection amount Qs to “0”.
Step 965: The CPU sets the air injection amount As to the water removal injection amount Ab.
That is, in this case, water removal control is executed. Specifically, fuel is not injected from the main fuel injection valve 64 and the secondary fuel injection valve 65, while air is injected from the air injection valve 67.

On the other hand, if the number of rotations of the crankshaft 15 after cranking has started has reached the starting control rotation speed Ca2, the CPU judges "Yes" in step 920 and sequentially executes the processes of steps 925 to 932 described below. Next, the CPU proceeds to step 435.

Step 925: The CPU sets the main fuel injection amount Qm to a predetermined startup main injection amount Qc1.
Step 930: The CPU sets the secondary fuel injection amount Qs to a predetermined startup secondary injection amount Qc2.
Step 932: The CPU sets the air injection amount As to the water removal injection amount Ab.
The startup main injection amount Qc1 and the startup sub injection amount Qc2 are each a fuel injection amount adapted to allow the internal combustion engine 2 to promptly start operation by cranking.

When the main fuel injection amount Qm and the secondary fuel injection amount Qs are set to values greater than "0", the CPU executes a routine not shown to inject fuel from the main fuel injection valve 64 and the secondary fuel injection valve 65, and ignite the mixture containing fuel from the spark plug 66. That is, when the crank angle CA of one of the multiple cylinders provided in the internal combustion engine 2 reaches the fuel injection angle, the CPU injects fuel equal to the main fuel injection amount Qm and the secondary fuel injection amount Qs from the main fuel injection valve 64 and the secondary fuel injection valve 65 of that cylinder. After that, when the crank angle CA of that cylinder reaches the ignition angle, the CPU generates a spark in the spark plug 66 of that cylinder to ignite the mixture containing fuel. The fuel injection from the main fuel injection valve 64 and the fuel injection from the secondary fuel injection valve 65 may be performed at different times.

When the internal combustion engine 2 starts operating as a result of fuel injection by the main fuel injection valve 64 and the secondary fuel injection valve 65 and ignition of the air-fuel mixture by the spark plug 66, together with cranking, the CPU judges "Yes" in step 435 and executes the processes of steps 440 to 450 in order. Next, the CPU proceeds to step 995. On the other hand, if the internal combustion engine 2 has not yet started operating, the CPU judges "No" in step 435 and proceeds directly to step 995.

(Specific operation - when operation stops)
When the CPU determines "No" in step 330, or when the CPU ends the process of step 340, the CPU proceeds to step 845 and executes the "engine stop process routine" shown in the flowchart of Fig. 10. That is, during the period in which the stop control flag Xd is "1", the CPU repeatedly executes the routine of Fig. 10.

More specifically, the CPU proceeds from step 1000 to step 1005 in FIG. 10, and after detecting an engine stop request, determines whether the number of revolutions of the crankshaft 15 has reached the stop control revolution number Cd2.

If the number of revolutions of the crankshaft 15 after the engine stop request is detected has not yet reached the stop control revolutions Cd2, the CPU judges "No" in step 1005 and executes the processing of steps 1040 to 1050 described below in order. Next, the CPU proceeds to step 1095 to end the processing of the routine in FIG. 10, and then ends the processing of the routine in FIG. 8.

Step 1040: The CPU sets the main fuel injection amount Qm to a predetermined idle main injection amount Qi1.
Step 1045: The CPU sets the secondary fuel injection amount Qs to a predetermined idle secondary injection amount Qi2.
Step 1050: The CPU sets the air injection amount As to the water removal injection amount Ab.
The idle main injection amount Qi1 and the idle sub injection amount Qi2 are each a fuel injection amount adapted so that the engine speed NE of the internal combustion engine 2 becomes a predetermined idle speed.

On the other hand, if the number of revolutions of the crankshaft 15 after detecting the engine stop request has reached the stop control revolutions Cd2, the CPU judges "Yes" in step 1005 and sequentially executes the processes of steps 1015 and 1020, and steps 530 and 535, which will be described below. Next, the CPU proceeds to step 1095.

Step 1015: The CPU sets the main fuel injection amount Qm to “0”.
Step 1020: The CPU sets the secondary fuel injection amount Qs to “0”.
That is, in this case, the operation of the internal combustion engine 2 is stopped.

As described above, the ECU 41 controls the tumble valve 27 when the internal combustion engine 1 starts and stops to execute water removal control that increases the airflow generated near the center electrode 17a and outer electrode 17b of the spark plug 17. Similarly, the ECU 42 controls the air injection valve 67 when the internal combustion engine 2 starts and stops to execute water removal control that increases the airflow generated near the center electrode 66a and outer electrode 66b of the spark plug 66. This removes water adhering to the electrodes of the spark plugs 17 and 66, reducing the possibility of misfires. Therefore, the possibility of the internal combustion engines 1 and 2 being unable to start operating due to misfires of the spark plugs 17 and 66 is reduced.

In particular, when the internal combustion engines 1, 2 start operating, the ECUs 41, 42 start water removal control before fuel injection by the fuel injection valve 16 or the secondary fuel injection valve 65 starts. Therefore, even in the internal combustion engines 1, 2 that use hydrogen as fuel, which has a relatively high water vapor concentration in the combustion gas, the possibility of misfire in the ignition plugs 17, 66 is reduced.

In addition, hydrogen, which is the fuel for the internal combustion engine 1, has a wide flammability limit (combustion range) and low ignition energy, making it highly ignitable. Therefore, by controlling the tumble valve 27 to a closed state during startup (cranking), the airflow in the combustion chamber 19 is increased, and so there is little chance of the mixture not burning properly even if the spark plug 17 generates a spark. In other words, there is little chance that the airflow near the electrode of the spark plug 17 is increased due to the control of the tumble valve 27 associated with the water removal control, resulting in the mixture not being able to be ignited.

Although the embodiment of the present invention has been described above with reference to the above structure, many alternatives, improvements, and modifications are possible without departing from the scope of the present invention. Accordingly, the present invention may include all alternatives, improvements, and modifications that do not depart from the spirit and scope of the appended claims. The present invention is not limited to the specific structure described above, and may be modified, for example, as follows:

The ECUs 41, 42 always execute water removal control when the internal combustion engines 1, 2 start to operate and when they stop to operate. Alternatively, the ECUs 41, 42 may execute water removal control only when a predetermined condition is met when the internal combustion engines 1, 2 start to operate and when they stop to operate. For example, the ECUs 41, 42 may execute water removal control only when the time that has elapsed since the internal combustion engines 1, 2 stopped to operate is longer than a predetermined threshold value when the internal combustion engines 1, 2 start to operate. Similarly, the ECUs 41, 42 may execute water removal control only when the time that has elapsed since the internal combustion engines 1, 2 started to operate is longer than a predetermined threshold value when the internal combustion engines 1, 2 stop to operate.

In addition, if the vehicle is a hybrid vehicle that is equipped with an electric motor as a driving force source in addition to the internal combustion engines 1 and 2 and in which the internal combustion engines 1 and 2 are repeatedly started and stopped while the vehicle is traveling, the ECUs 41 and 42 may execute water removal control when a predetermined condition is met even while the vehicle is traveling.

The ECUs 41 and 42 determined whether or not to continue the control depending on whether the number of revolutions of the crankshaft 15 reached the start control revolutions Ca1, Ca2 or the stop control revolutions Cd1, Cd2. Alternatively, the ECUs 41 and 42 may determine whether or not to continue the control depending on whether or not the time that has elapsed since the start of the water removal control has exceeded a predetermined threshold value.

The internal combustion engines 1 and 2 are engines that operate using hydrogen as fuel. Alternatively, the internal combustion engines 1 and 2 may be engines that operate using ammonia as fuel. That is, the fuel injector 16, the main fuel injector 64, and the auxiliary fuel injector 65 may be configured to inject ammonia. Alternatively, the internal combustion engines 1 and 2 may be engines that operate using gasoline or diesel as fuel.

When performing water removal control, the ECU 41 increases the airflow near the electrode of the spark plug 17 by controlling the tumble valve 27 to achieve a closed state (i.e., a state in which the lower flow passage 21b is closed). Alternatively, when performing water removal control, the ECU 41 may increase the airflow near the electrode of the spark plug 17 by controlling the tumble valve 27 so that the flow passage cross-sectional area of the lower flow passage 21b becomes somewhat smaller compared to the open state. In other words, the lower flow passage 21b does not have to be closed when performing water removal control.

On the other hand, if controlling the tumble valve 27 to an open state increases the airflow near the electrode of the spark plug 17 due to factors such as the shape of the intake pipe 21 and the position of the spark plug 17 in the combustion chamber 19, the ECU 41 may control the tumble valve 27 to an open state when performing water removal control.

Alternatively, the ECU 41 may increase the airflow near the electrode of the spark plug 17 by a method other than controlling the tumble valve 27. For example, if the internal combustion engine 1 is equipped with a well-known swirl control valve, the ECU 41 may increase the airflow near the electrode of the spark plug 17 by controlling the swirl control valve when performing water removal control.

The internal combustion engine 1 was a direct injection engine in which the fuel injection valve 16 was disposed in the combustion chamber 19. Alternatively, the internal combustion engine 1 may be a port injection engine in which the fuel injection valve is disposed in the intake port 22.

The ECU 42 performed the water removal control by injecting air through the air injection valve 67 during the exhaust stroke of the internal combustion engine 2. In other words, the air injection valve 67 injected air when the crankshaft 15 was rotating. Alternatively, the air injection valve 67 may inject air when the crankshaft 15 was not rotating. For example, if the exhaust valve 33 of the internal combustion engine 2 is an electromagnetic valve that is opened and closed by an electromagnet instead of an exhaust camshaft, the ECU 42 may execute the water removal control by controlling the air injection valve 67 to inject air when the exhaust valve 33 is open before the start of cranking at the start of operation of the internal combustion engine 2. Similarly, the ECU 42 may execute the water removal control by controlling the air injection valve 67 to inject air when the exhaust valve 33 is open after the operation of the internal combustion engine 2 is stopped (i.e., after the rotation of the crankshaft 15 is finished). In this case, if the water removal control is not performed, no airflow occurs near the electrode of the spark plug 66, whereas if the water removal control is performed, airflow occurs near the electrode of the spark plug 66. In other words, the water removal control increases the airflow near the electrode.

Reference Signs List 1, 2... Internal combustion engine 10... Main body 11... Cylinder block 12, 12a... Cylinder head 13... Piston 14... Connecting rod 15... Crankshaft 16... Fuel injection valve 17... Spark plug 17a... Center electrode 17b... Outer electrode 18... Starter motor 19... Combustion chamber 20... Intake system 21... Intake pipe 21a... Upper flow passage 21b... Lower flow passage 22... Intake port 23... Air cleaner 24... Intake valve 25... Throttle valve 25a... Throttle valve actuator 26... Flow passage wall 27... Tumble control valve (tumble valve)
27a... shaft 27b... tumble control actuator 30... exhaust system 31... exhaust pipe 32... exhaust port 33... exhaust valve 34... EGR pipe 35... EGR valves 41, 42... ECU
51...intake air amount sensor 52...crank angle sensor 53...accelerator opening sensor 54...vehicle speed sensor 55...ignition switch 61...main combustion chamber 62...auxiliary combustion chamber 63...divider plate 64...main fuel injection valve 65...auxiliary fuel injection valve 66...ignition plug 66a...center electrode 66b...outer electrode 67...air injection valve 68...air supply pipe

Claims (5)

1. An internal combustion engine,
A fuel injection valve;
a spark plug having an electrode located in the combustion chamber;
and a control unit that executes water removal control to remove water adhering to the electrodes by increasing an airflow generated near the electrodes when the internal combustion engine starts and stops operating. 2. The internal combustion engine according to claim 1,
a tumble control valve that is controlled to increase the tumble flow generated in the combustion chamber;
The control unit is
the tumble control valve is controlled during execution of the water removal control to increase the airflow generated in the vicinity of the electrode. 2. The internal combustion engine according to claim 1,
The combustion chamber is
a main combustion chamber; and a sub-combustion chamber communicating with the main combustion chamber and having an air injection valve and the electrode disposed therein;
The control unit is
The internal combustion engine causes the air injection valve to inject air into the auxiliary combustion chamber when the water removal control is executed. An internal combustion engine according to any one of claims 1 to 3,
The control unit is
The water removal control is started before fuel injection by the fuel injection valve is started. An internal combustion engine according to any one of claims 1 to 3,
The fuel injection valve is
An internal combustion engine that injects hydrogen or ammonia.

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