Ignition control device for internal combustion engine and ignition control method for internal combustion engine

Abstract

To provide an ignition control device for an internal combustion engine and an ignition control method for the internal combustion engine capable of suppressing abnormal discharge of an ignition plug without requiring addition of components in the internal combustion engine using hydrogen as fuel.SOLUTION: An ignition control device 100 for an internal combustion engine is for a four-cycle internal combustion engine 1 using hydrogen as fuel. The ignition control device includes: an ECU 10 that generates an ignition signal on the basis of an operating state of the internal combustion engine 1 including a crank angle of the internal combustion engine 1; and an ignition device 31 that sparks an ignition plug 30 of the internal combustion engine 1 on the basis of the ignition signal. As the ignition signals, the ECU 10 generates a first ignition signal for sparking the ignition plug 30 in a compression stroke or an expansion stroke of the internal combustion engine 1 and a second ignition signal for sparking the ignition plug 30 for a valve opening period of an exhaust valve 3b of the internal combustion engine 1.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an ignition control device for an internal combustion engine and an ignition control method for an internal combustion engine.

Background Art

[0002] Conventionally, in an external mixture type hydrogen engine, a configuration is known in which the high voltage on the secondary side supplied from an ignition coil to an ignition plug cable is divided by an earth cable having an electric resistance (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above prior art, an earth cable is added to the ignition plug cable to prevent the remaining electric energy from accumulating in the stray capacitance of the high voltage portion from the ignition coil to the ignition plug, thereby preventing the occurrence of backfire due to abnormal discharge. However, this method has room for improvement in terms of an increase in the number of parts and the layout space for the electric resistance.

[0005] An object of the present invention is to provide an ignition control device for an internal combustion engine and an ignition control method for an internal combustion engine that can suppress abnormal discharge of an ignition plug without requiring an addition of parts in an internal combustion engine using hydrogen as fuel.

Means for Solving the Problems

[0006] One aspect of the present invention is an ignition control device for a four - cycle internal combustion engine that uses hydrogen as fuel, comprising: an ignition signal generation unit that generates an ignition signal based on the operating state of the internal combustion engine including the crank angle of the internal combustion engine; and an ignition device that causes the spark plug of the internal combustion engine to spark based on the ignition signal. The ignition signal generation unit generates, as the ignition signal, a first ignition signal that causes the spark plug to spark during the compression stroke or the expansion stroke of the internal combustion engine, and a second ignition signal that causes the spark plug to spark during the valve opening period of the exhaust valve of the internal combustion engine.

[0007] In the ignition control device for an internal combustion engine according to one aspect of the present invention, a second ignition signal that causes the spark plug to spark during the valve opening period of the exhaust valve of the internal combustion engine is generated by the ignition signal generation unit. For example, as a result of the spark plug being caused to spark during the compression stroke or the expansion stroke based on the first ignition signal, even if electrical energy remains in the ignition device, new energy is supplied based on the second ignition signal during the valve opening period of the exhaust valve, and the spark plug is caused to spark. Here, during the valve opening period of the exhaust valve, the in - cylinder pressure drops compared to the compression stroke or the expansion stroke, so the breakdown voltage becomes smaller, and the discharge maintenance voltage at which the spark based on the second ignition signal disappears becomes smaller. As a result, there is no state in which electrical energy remains such that abnormal discharge occurs where the spark plug sparks during the intake stroke of the internal combustion engine. Therefore, according to the ignition control device for an internal combustion engine according to one aspect of the present invention, abnormal discharge of the spark plug can be suppressed without the need to add components in an internal combustion engine that uses hydrogen as fuel.

[0008] In one embodiment, the ignition signal generation unit may generate the ignition signal such that the energization time of the ignition coil by the second ignition signal is shorter than the energization time of the ignition coil by the first ignition signal. In this case, for example, compared with the case where the energization times of the ignition coils are equal to each other, the spark of the spark plug by the second ignition signal becomes weaker than the spark of the spark plug by the first ignition signal, and the consumption of the spark plug can be suppressed.

[0009] In one embodiment, the ignition signal generation unit may generate a second ignition signal so as to cause the spark plug to spark during the valve closing period of the intake valve of the internal combustion engine in the latter half of the valve opening period of the exhaust valve. In this case, for example, since the in-cylinder pressure is lower than when the spark plug is caused to spark in the first half of the valve opening period of the exhaust valve, the breakdown voltage is reduced. Therefore, the remaining electrical energy can be more reliably reduced.

[0010] Another aspect of the present invention is an ignition control method for a four-cycle internal combustion engine using hydrogen as fuel, including an ignition signal generation unit that generates an ignition signal based on the operating state of the internal combustion engine including the crank angle of the internal combustion engine, and an ignition device that causes the spark plug of the internal combustion engine to spark based on the ignition signal. Using these, as the ignition signal, a first ignition signal that causes the spark plug to spark during the compression stroke or the expansion stroke of the internal combustion engine and a second ignition signal that causes the spark plug to spark during the valve opening period of the exhaust valve of the internal combustion engine are generated by the ignition signal generation unit, and based on the second ignition signal, the spark plug is caused to spark during the valve opening period of the exhaust valve.

[0011] In the ignition control method for an internal combustion engine according to another aspect of the present invention, a second ignition signal that causes the spark plug to spark during the valve opening period of the exhaust valve of the internal combustion engine is generated using the ignition signal generation unit. For example, as a result of the spark plug being caused to spark during the compression stroke or the expansion stroke based on the first ignition signal, even if electrical energy remains in the ignition device, new energy is supplied based on the second ignition signal during the valve opening period of the exhaust valve and the spark plug is caused to spark. Here, since the in-cylinder pressure decreases during the valve opening period of the exhaust valve compared to the compression stroke or the expansion stroke, the breakdown voltage decreases, and the discharge maintenance voltage at which the spark based on the second ignition signal disappears decreases. As a result, the state is such that there is no remaining electrical energy that would cause abnormal discharge where the spark plug sparks during the intake stroke of the internal combustion engine. Therefore, according to the ignition control method for an internal combustion engine according to another aspect of the present invention, abnormal discharge of the spark plug can be suppressed without the need to add components in an internal combustion engine using hydrogen as fuel.

Advantages of the Invention

[0012] According to the present invention, abnormal discharge of an ignition plug can be suppressed without adding parts in an internal combustion engine using hydrogen as fuel.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate explanations are omitted.

[0015] FIG. 1 is a schematic configuration diagram of an internal combustion engine including an ignition control device for the internal combustion engine of the embodiment. As shown in FIG. 1, the ignition control device 100 for the internal combustion engine according to the embodiment is applied to the internal combustion engine 1. The internal combustion engine 1 is configured as a hydrogen engine that operates using hydrogen gas (hereinafter simply referred to as "hydrogen") as fuel. The internal combustion engine 1 is configured as, for example, a four-cycle port injection reciprocating engine. The internal combustion engine 1 has a plurality (for example, four) of cylinders 2.

[0016] Figure 2 is a schematic cross-sectional view taken along the line X-X of Figure 1. As shown in Figures 1 and 2, the internal combustion engine 1 has a cylinder head 3 including an intake valve 3a and an exhaust valve 3b, and a piston 5 provided in a cylinder 4.

[0017] An intake port 3c and an exhaust port 3d are formed in the cylinder head 3 so as to communicate with the combustion chamber 6. An intake valve 3a is provided at the downstream end of the intake port 3c. An exhaust valve 3b is provided at the upstream end of the exhaust port 3d. A pipe 8 after the branch of the intake manifold is connected to the upstream side of the intake port 3c. The pipe 8 after the branch of the intake manifold forms a part of the intake passage 7 of the internal combustion engine 1.

[0018] In the intake passage 7, for example, an air cleaner 16, a compressor 41 of a turbocharger 40, an intercooler 17, and a throttle valve 18 are arranged in order from the upstream side to the downstream side. In the exhaust passage 9, for example, a turbine 42 of the turbocharger 40 is arranged.

[0019] The internal combustion engine 1 may be provided with an EGR unit 24 that recirculates a part of the burned gas generated in the combustion chamber 6 as EGR (exhaust gas recirculation) gas to the intake passage 7. The EGR unit 24 may have an EGR passage 25, an EGR valve 26, an EGR cooler 27, a bypass passage 28, and a switching valve 29.

[0020] The internal combustion engine 1 is provided with a plurality of injectors 11 that inject fuel toward the intake port 3c. Each of the plurality of injectors 11 is attached to a rail (not shown), for example, and hydrogen is supplied from a fuel tank (not shown) to the rail. The injector 11 injects the hydrogen supplied from the rail during the intake stroke in which the intake valve 3a is open.

[0021] In each cylinder 2, a combustion chamber 6 is defined by a cylinder head 3, a cylinder 4, and a piston 5. An ignition plug 30 is attached to the top of the combustion chamber 6. The internal combustion engine 1 takes in air and hydrogen through an intake valve 3a, burns the hydrogen by ignition (spark) of the ignition plug 30 in the combustion chamber 6, and exhausts the exhaust gas generated by the combustion through an exhaust valve 3b.

[0022] The ignition control device 100 of the internal combustion engine is an ignition system of the internal combustion engine 1, and generates a spark for the ignition plug 30 that defines the energization time and ignition timing for each cylinder. The ignition control device 100 of the internal combustion engine includes an ECU [Electronic Control Unit] (ignition signal generation unit) 10 and an ignition device 31.

[0023] The ECU 10 is an electronic control unit that controls the internal combustion engine 1. The ECU 10 has a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], a communication circuit, etc. In the ECU 10, for example, a program stored in the ROM is loaded into the RAM, and various functions are realized by executing the program loaded into the RAM with the CPU. The ECU 10 may be composed of a plurality of electronic units.

[0024] Connected to the ECU 10 are an engine rotation sensor (crank angle sensor) 21 and an intake air amount sensor 22 as sensors for acquiring the operating state of the internal combustion engine 1. The engine rotation sensor 21 is a known detector that detects the engine speed of the internal combustion engine 1. The engine rotation sensor 21 is a crank angle sensor that detects the angular position of the crankshaft of the internal combustion engine 1. The engine rotation sensor 21 outputs a detection signal of the detected engine speed to the ECU 10. The intake air amount sensor 22 is provided in the intake passage 7 of the internal combustion engine 1 and is a known detector that detects a detection value related to the intake air amount of the internal combustion engine 1. The intake air amount sensor 22 outputs a detection signal of the intake air amount of the internal combustion engine 1 to the ECU 10.

[0025] The ECU 10 recognizes the operating state of the internal combustion engine 1 based on the detection values from various sensors. The ECU 10 calculates various control quantities including the energization time and ignition timing based on the operating state of the internal combustion engine 1, and controls the internal combustion engine 1.

[0026] The ECU 10 generates an ignition signal based on the operating state of the internal combustion engine 1 including the crank angle of the internal combustion engine 1. For example, when the ignition timing and the energization time are determined, the ECU 10 calculates, in an interrupt process at a predetermined crank angle before the ignition timing, the crank angle counted backward from the ignition timing to determine how many crank angles before the energization should start. The ECU 10 transmits an ignition signal so that the energization starts from the calculated crank angle at which the energization should start.

[0027] FIG. 3(a) is a schematic configuration diagram illustrating an ignition device in an ignition control device for an internal combustion engine according to an embodiment. The ignition device 31 causes the spark plug of the internal combustion engine 1 to spark based on the ignition signal from the ECU 10. The ignition device 31 is, as an example, an igniter of a direct ignition system, and directly distributes the secondary high voltage generated in the ignition coil 32 to the spark plug 30 by energizing or interrupting the primary current according to the ignition signal. The ignition device 31 is provided in the number corresponding to the number of cylinders 2 so that the ignition coil 32 and the spark plug 30 correspond one-to-one. Note that the circuit of the ignition device 31 in FIG. 3(a) omits the illustration of parts other than the main part.

[0028] The power transistor 34 energizes or interrupts the primary current of the ignition coil 32 based on the ignition signal from the ECU 10. In the power transistor 34, the ignition signal from the ECU 10 is input to the base, one end of the primary coil of the ignition coil 32 is connected to the collector, and the negative side (ground) of the battery 33 is connected to the emitter. When the ignition signal from the ECU 10 is input (Tr On), the power transistor 34 turns on, and when the ignition signal from the ECU 10 is not input, the power transistor 34 turns off. Note that "the ignition signal is input" may mean a high signal, and "the ignition signal is not input" may mean a low signal.

[0029] The other end of the primary coil of the ignition coil 32 is connected to the positive side of the battery 33. One end of the secondary coil of the ignition coil 32 is connected to the spark plug 30. The other end of the secondary coil of the ignition coil 32 is connected to the positive side of the battery 33. When the power transistor 34 is turned on, current flows through the primary coil of the ignition coil 32. When the power transistor 34 is turned off, no current flows through the primary coil of the ignition coil 32.

[0030] In the ignition coil 32, when the power transistor 34 is on, the primary coil is energized, and when the power transistor 34 switches from on to off from this state, the energization of the primary coil is cut off and a high voltage is generated in the secondary coil. The ignition coil 32 supplies the high voltage generated in the secondary coil to the spark plug 30.

[0031] The spark (discharge) by the spark plug 30 is composed of a rapid "capacitive discharge" that occurs immediately after the inter-electrode voltage exceeds the breakdown voltage, and a subsequent "inductive discharge" that gradually decays. For example, in an internal combustion engine using gasoline as fuel, since an ionic current flows between the electrodes, it is difficult for electrical energy (inter-electrode voltage) to remain after the inductive discharge. On the other hand, in an internal combustion engine using hydrogen as fuel, since no ionic current flows between the electrodes, it is considered that the inter-electrode voltage is more likely to remain after the inductive discharge than in an internal combustion engine using gasoline as fuel. The height of the inter-electrode voltage remaining after such an inductive discharge is considered to be correlated with at least one of the breakdown voltage and the discharge maintenance voltage that can maintain the inductive discharge. In particular, in the compression stroke or expansion stroke where the main ignition for causing combustion in the air-fuel mixture by sparking the spark plug 30 near the top dead center of the piston 5 is carried out, the breakdown voltage and the discharge maintenance voltage increase according to the height of the in-cylinder pressure. Therefore, the electrical energy remaining in the ignition device 31 and the inter-electrode voltage of the spark plug 30 after the spark ends tend to be high according to the height of the in-cylinder pressure.

[0032] Here, according to Paschen's law, which expresses the voltage (dielectric breakdown voltage) required for spark discharge to occur between electrodes as a function of the product of atmospheric pressure and the distance between the electrodes, the dielectric breakdown voltage tends to be lower as the atmospheric pressure is lower, except in the vacuum region. This dielectric breakdown voltage also varies depending on the composition of the gas. For example, it is lower than the dielectric breakdown voltage for a mixture containing hydrogen and the dielectric breakdown voltage for air. Then, if the intake stroke starts while electrical energy remains residual, hydrogen flows into the place where the in-cylinder pressure has dropped, and there is a possibility that the dielectric breakdown voltage will drop below the inter-electrode voltage of the ignition plug 30. As a result, a spark (abnormal discharge) due to the residual energy may occur, and there is a risk that the hydrogen newly entering the combustion chamber 6 in the intake stroke will be ignited by the abnormal discharge and backfire will occur.

[0033] Therefore, in order to suppress such abnormal discharges, the ignition control device 100 of the internal combustion engine is configured to reduce the residual energy of the ignition device 31 before new hydrogen enters the combustion chamber 6 in the intake stroke. The ECU 10 generates, as ignition signals, a first ignition signal for causing the ignition plug 30 to spark during the compression stroke or the expansion stroke of the internal combustion engine 1, and a second ignition signal for causing the ignition plug 30 to spark during the valve opening period of the exhaust valve 3b of the internal combustion engine 1.

[0034] The first ignition signal is a signal for main ignition that causes the ignition plug 30 to spark near the top dead center of the piston 5 to cause combustion in the air-fuel mixture. The second ignition signal is an additional ignition signal for reducing the residual energy of the ignition device 31 before new hydrogen enters the combustion chamber 6 in the intake stroke. The second ignition signal is, for example, an ignition signal for causing the ignition plug 30 to spark during the valve opening period of the exhaust valve 3b immediately after the compression stroke or the expansion stroke in which the first ignition signal is applied.

[0035] FIG. 3(b) is a diagram for explaining an operation example of the spark of the spark plug based on the ignition signal. The first ignition signal causes combustion in the air-fuel mixture near the top dead center of the piston 5. The ignition timing and the energization time are determined by the ECU 10 based on the operating state of the internal combustion engine 1 by a known method. In the example of FIG. 3(b), the first ignition signal SS1 is input from the ECU 10 so that the spark plug 30 generates a spark during the compression stroke or the expansion stroke of the internal combustion engine 1. When the power transistor 34 is turned on by the input of the first ignition signal SS1, the primary coil is energized (V1 = battery voltage), and a current flows through the primary coil of the ignition coil 32 (I1 is about 4 A). When the power transistor 34 switches from on to off from that state, the energization of the primary coil is cut off and a high voltage is generated in the secondary coil (V2 = about 30,000 V).

[0036] The second ignition signal has its ignition timing determined by the ECU 10 based on the operating state of the internal combustion engine 1 so that the spark plug 30 generates a spark during the valve opening period of the exhaust valve 3b of the internal combustion engine 1. The ECU 10 generates the second ignition signal so that, for example, the spark plug 30 generates a spark during the valve closing period of the intake valve 3a of the internal combustion engine 1 in the second half of the valve opening period of the exhaust valve 3b. That is, the ignition timing corresponding to the second ignition signal is included in the period when only the exhaust valve 3b is open. The ignition timing corresponding to the second ignition signal may be immediately before the intake valve 3a opens. The ignition timing corresponding to the second ignition signal may also be immediately after the exhaust valve 3b opens during the expansion stroke.

[0037] Note that "the exhaust valve is open" may refer to a state where the opening amount of the exhaust valve 3b is larger than a predetermined exhaust valve opening determination value. The opening amount of the exhaust valve 3b may be the lift amount of the exhaust valve 3b from the state where the exhaust valve 3b is seated on the valve seat. Also, "the intake valve is closed" may refer to a state where the opening amount of the intake valve 3a is equal to or less than a predetermined intake valve closing determination value. "The intake valve is closed" may refer to a state where the opening amount of the intake valve 3a is 0. The opening amount of the intake valve 3a may be the lift amount of the intake valve 3a from the state where the intake valve 3a is seated on the valve seat.

[0038] The second ignition signal has its energization time determined by the ECU 10 based on the operating state of the internal combustion engine 1. The ECU 10 generates an ignition signal such that, for example, the energization time of the ignition coil 32 by the second ignition signal SS2 is shorter than the energization time of the ignition coil 32 by the first ignition signal SS1. During the opening period of the exhaust valve 3b, the in-cylinder pressure is lower (see FIG. 4(c)) and the breakdown voltage is also lower compared to the periods when the exhaust valve 3b is closed, such as during the compression and expansion strokes. Therefore, the energy supplied to the ignition coil 32 based on the second ignition signal may be smaller than the energy supplied to the ignition coil 32 based on the first ignition signal.

[0039] In the example of FIG. 3(b), the second ignition signal SS2 is input from the ECU 10 so as to spark the spark plug 30 during the opening period of the exhaust valve 3b of the internal combustion engine 1. When the power transistor 34 is on due to the input of the second ignition signal SS2, current flows through the primary coil (V1 = battery voltage). Current flows through the primary coil of the ignition coil 32. When the power transistor 34 switches from on to off from that state, the energization of the primary coil is cut off and a high voltage is generated in the secondary coil. When the energization time of the ignition coil 32 by the second ignition signal SS2 is shorter than the energization time of the ignition coil 32 by the first ignition signal SS1, I1 and V2 corresponding to the second ignition signal SS2 are smaller than I1 and V2 corresponding to the first ignition signal SS1.

[0040] FIG. 4(a) is a diagram illustrating the inter-electrode voltage in a comparative example. FIG. 4(b) is a diagram illustrating the inter-electrode voltage in an embodiment. In the example of FIG. 4(a), at the end of the compression stroke near the top dead center of the piston 5, a spark SP1 of the spark plug 30 is generated by the first ignition signal SS1. During a period when the exhaust valve 3b is closed, such as in the compression stroke and the expansion stroke, the breakdown voltage and the discharge maintenance voltage are high according to the high in-cylinder pressure. According to the heights of the breakdown voltage and the discharge maintenance voltage, there is a tendency for the electrical energy remaining in the ignition device 31 and the inter-electrode voltage of the spark plug 30 to be high after the end of the spark SP1. The remaining electrical energy remains high until the intake stroke, and when the intake stroke starts and the in-cylinder pressure decreases and the breakdown voltage drops below the inter-electrode voltage of the spark plug 30, there is a possibility that a spark (abnormal discharge) caused by the remaining energy may occur.

[0041] On the other hand, in the example of FIG. 4(b), similar to the example of FIG. 4(a), at the end of the compression stroke near the top dead center of the piston 5, a spark SP1 of the spark plug 30 is generated by the first ignition signal SS1. Here, during the valve opening period of the exhaust valve 3b thereafter, intentionally, a spark SP2 of the spark plug 30 is generated by the second ignition signal SS2. During the valve opening period of the exhaust valve 3b, such as in the exhaust stroke, the breakdown voltage and the discharge maintenance voltage become lower according to the lower in-cylinder pressure compared to the period when the exhaust valve 3b is closed, such as in the compression stroke and the expansion stroke. Since the discharge maintenance voltage at which the spark SP2 based on the second ignition signal SS2 disappears becomes small, the electrical energy and the inter-electrode voltage remaining after the end of the spark SP2 can be lowered, and the remaining energy of the ignition device 31 can be reduced before new hydrogen enters the combustion chamber 6 in the immediately following intake stroke.

[0042] An example of the processing of the ECU 10 and an example of the operation of the ignition control device 100 of the internal combustion engine (an example of the ignition control method of the internal combustion engine) will be described with reference to FIG. 5. FIG. 5 is a flowchart showing an example of the processing of the ECU in FIG. 1. The processing in FIG. 5 is executed, for example, during the operation of the internal combustion engine 1.

[0043] As shown in FIG. 5, in S10, the ECU 10 acquires the operating state of the internal combustion engine 1. The ECU 10 acquires the crank angle and the engine speed based on the detection result of the engine rotation sensor 21. The ECU 10 acquires the intake air amount of the internal combustion engine 1 based on the detection result of the intake air amount sensor 22.

[0044] In S11, the ECU 10 determines the ignition timing and the energization time. Based on the operating state of the internal combustion engine 1, the ECU 10 generates, as ignition signals, a first ignition signal for sparking the ignition plug 30 during the compression stroke or the expansion stroke of the internal combustion engine 1, and a second ignition signal for sparking the ignition plug 30 during the valve opening period of the exhaust valve 3b of the internal combustion engine 1.

[0045] In S12, the ECU 10 transmits the first ignition signal for sparking during the compression stroke or the expansion stroke. The ECU 10 transmits the first ignition signal SS1 to the ignition device 31 during the compression stroke or the expansion stroke of the internal combustion engine 1 so as to cause combustion in the air-fuel mixture near the top dead center of the piston 5. That is, based on the first ignition signal, the ignition plug is sparked during the compression stroke or the expansion stroke.

[0046] In S13, the ECU 10 transmits the second ignition signal for sparking during the valve opening period of the exhaust valve. The ECU 10 transmits the second ignition signal SS2 to the ignition device 31 during the valve opening period of the exhaust valve 3b of the internal combustion engine 1 so as to reduce the residual energy of the ignition device 31 before the immediately following intake stroke. That is, based on the second ignition signal, the ignition plug is sparked during the valve opening period of the exhaust valve. Then, the ECU 10 ends the process of FIG. 5, and may start the process of FIG. 5 again, for example, before the next compression stroke.

[0047] [Operation and Effect] In the ignition control device 100 for an internal combustion engine and the ignition control method for an internal combustion engine as described above, a second ignition signal SS2 for sparking the spark plug 30 during the valve opening period of the exhaust valve 3b of the internal combustion engine 1 is generated by the ECU 10. Based on the second ignition signal SS2, the ignition device 31 causes the spark plug 30 to spark during the valve opening period of the exhaust valve 3b. As a result, for example, if electrical energy remains in the ignition device 31 after the spark plug 30 has been sparked based on the first ignition signal SS1 during the compression stroke or the expansion stroke, new energy is supplied based on the second ignition signal SS2 during the valve opening period of the exhaust valve 3b, causing the spark plug 30 to spark. Here, since the in-cylinder pressure decreases during the valve opening period of the exhaust valve 3b compared to the compression stroke or the expansion stroke, the breakdown voltage decreases, and the voltage at which the spark based on the second ignition signal SS2 disappears decreases. As a result, there is no state in which electrical energy remains such that abnormal discharge occurs where the spark plug 30 sparks during the intake stroke of the internal combustion engine 1. Therefore, according to the ignition control device 100 for an internal combustion engine and the ignition control method for an internal combustion engine, abnormal discharge of the spark plug 30 can be suppressed without the need to add components in the internal combustion engine 1 that uses hydrogen as fuel.

[0048] The ECU 10 generates an ignition signal such that the energization time of the ignition coil 32 by the second ignition signal SS2 is shorter than the energization time of the ignition coil 32 by the first ignition signal SS1. Thereby, for example, compared to the case where the energization times of the ignition coils 32 are equal to each other, the spark of the spark plug 30 by the second ignition signal SS2 becomes weaker than the spark of the spark plug 30 by the first ignition signal SS1, and the consumption of the spark plug 30 can be suppressed.

[0049] The ECU 10 generates the second ignition signal SS2 so as to cause the spark plug 30 to spark during the valve closing period of the intake valve 3a of the internal combustion engine 1 in the latter half of the valve opening period of the exhaust valve 3b. Thereby, for example, since the in-cylinder pressure is lower compared to the case where the spark plug 30 is sparked in the first half of the valve opening period of the exhaust valve 3b, the breakdown voltage decreases. Therefore, the remaining electrical energy can be more reliably reduced.

[0050] [Modification Example] As described above, the embodiments according to the present invention have been explained, but the present invention is not limited to the above-described embodiments.

[0051] In the above embodiment, the ECU 10 generated the second ignition signal so as to spark the ignition plug 30 during the valve closing period of the intake valve 3a of the internal combustion engine 1 in the latter half of the valve opening period of the exhaust valve 3b. However, the present invention is not limited to this example. The ECU 10 may generate the second ignition signal so as to spark the ignition plug 30 in the first half of the valve opening period of the exhaust valve 3b.

[0052] In the above embodiment, the ECU 10 generated the ignition signal so that, for example, the energization time of the ignition coil 32 by the second ignition signal was shorter than the energization time of the ignition coil 32 by the first ignition signal. However, the present invention is not limited to this example. The energization time of the ignition coil 32 by the second ignition signal may be equal to the energization time of the ignition coil 32 by the first ignition signal.

[0053] In the above embodiment, the ignition device 31 is a direct ignition system that directly distributes the secondary high voltage generated in the ignition coil 32 to the ignition plug 30, and the ignition coil 32 and the ignition plug 30 corresponded one-to-one. However, the present invention is not limited to this example. The ignition device may be in a form in which one ignition coil corresponds to two ignition plugs. The ignition device may be in a distributor form. In addition, it is not essential for the ignition coil 32 to energize or cut off the primary current according to the ignition signal. The ignition device is not limited to the full transistor type as in the above embodiment, and may be a CDI [Capacitor Discharge Ignition] ignition system. Further, the ignition device may be a plasma ignition system or the like. The ignition device may be a spark ignition type ignition device that sparks the ignition plug of the internal combustion engine based on the ignition signal.

[0054] In the above embodiment, the in-vehicle ECU 10 is exemplified as the ignition signal generation unit, but the present invention is not limited to this example. For example, the ignition signal generation unit may be a handy device that is connected to a predetermined wiring of the internal combustion engine 1 and is used for maintenance or testing of the internal combustion engine 1, etc.

Explanation of Signs

[0055] 1... Internal combustion engine, 3a... Intake valve, 3b... Exhaust valve, 10... ECU (ignition signal generation unit), 30... Spark plug, 31... Ignition device, 32... Ignition coil, 100... Ignition control device for internal combustion engine, SS1... First ignition signal, SS2... Second ignition signal.

Claims

1. An ignition control device for a four-cycle internal combustion engine using hydrogen as fuel, comprising: an ignition signal generation unit that generates an ignition signal based on an operating state of the internal combustion engine including a crank angle of the internal combustion engine; an ignition device that causes a spark plug of the internal combustion engine to spark based on the ignition signal. The ignition signal generation unit generates, as the ignition signal, a first ignition signal that causes the spark plug to spark during a compression stroke or an expansion stroke of the internal combustion engine, and a second ignition signal that causes the spark plug to spark during an opening period of an exhaust valve of the internal combustion engine. An ignition control device for an internal combustion engine.

2. The ignition signal generation unit generates the ignition signal such that an energization time of an ignition coil by the second ignition signal is shorter than an energization time of the ignition coil by the first ignition signal. The ignition control device for an internal combustion engine according to Claim 1.

3. The ignition signal generation unit generates the second ignition signal such that the spark plug sparks during a valve closing period of an intake valve of the internal combustion engine in the second half of the opening period of the exhaust valve. The ignition control device for an internal combustion engine according to Claim 1 or 2.

4. An ignition control method for a four-cycle internal combustion engine using hydrogen as fuel, comprising: using an ignition signal generation unit that generates an ignition signal based on an operating state of the internal combustion engine including a crank angle of the internal combustion engine, and an ignition device that causes a spark plug of the internal combustion engine to spark based on the ignition signal, causing the ignition signal generation unit to generate, as the ignition signal, a first ignition signal that causes the spark plug to spark during a compression stroke or an expansion stroke of the internal combustion engine, and a second ignition signal that causes the spark plug to spark during an opening period of an exhaust valve of the internal combustion engine, causing the spark plug to spark during the opening period of the exhaust valve based on the second ignition signal. An ignition control method for an internal combustion engine.

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