Control device of spark ignition hydrogen engine and control method for spark ignition hydrogen engine

Abstract

To prevent backfire of an engine due to unintended discharging in an ignition plug at low cost, without generating a positive voltage during ignition coil charging, in a spark ignition hydrogen engine.SOLUTION: A control device of a spark ignition hydrogen engine sends, to an igniter of an ignition device, a main discharge ignition signal to ignite hydrogen mixture, and an auxiliary discharge ignition signal to reduce an open-circuit voltage of a secondary coil during an intake stroke compared to an open-circuit voltage at the end of main discharge. Therefore, it is possible to set the open-circuit voltage during the intake stroke to the minimum value of a breakdown voltage in the spark ignition hydrogen engine to prevent backfire of the engine.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a control device for a spark ignition type hydrogen engine and a control method for a spark ignition type hydrogen engine. [Background technology]

[0002] In a spark-ignition hydrogen engine, residual energy and high open-circuit voltage in the ignition coil can cause unintended spark discharges in the spark plug gap, leading to unintended ignition of the hydrogen mixture. This can cause backfires and serious damage to the engine's intake system. In relation to this problem, Patent Document 1 discloses an ignition device that prevents spark discharge due to the residual energy of the ignition coil by returning the residual energy of the ignition coil to a power source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2022 / 128603A1 Summary of the Invention [Problem to be solved by the invention]

[0004] The ignition device described in Patent Document 1 is configured to provide a bypass resistance element between the primary and secondary sides of the ignition coil, and to return residual energy on the secondary side of the ignition coil to a power source. However, providing a bypass resistance element in the ignition coil as in the ignition device described in Patent Document 1 poses a problem of increased manufacturing costs for the ignition coil. Furthermore, if a bypass resistance element is provided in the ignition coil as in the ignition device described in Patent Document 1, a positive voltage (on-voltage) is generated on the secondary side of the ignition coil when the ignition coil is charged, and this positive voltage may cause unintended spark discharge.

[0005] The present invention aims to provide a control device and a control method for a spark-ignition hydrogen engine that can prevent engine backfire caused by unintended spark discharge from the spark plug at low cost without generating positive voltage when charging the ignition coil. [Means for solving the problem]

[0006] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes multiple means for solving the above problems, but to cite one example, the control device for a spark-ignition hydrogen engine of the present invention comprises an ignition coil that generates a high voltage in a secondary coil by interrupting the current flowing through the primary coil, an igniter that conducts and interrupts the current flowing through this primary coil, an ignition plug that is connected to the secondary coil and generates a spark discharge and has an electrode located in the combustion chamber, and a control device that sends an ignition signal to the igniter. Here, the control device sends to the igniter a main discharge ignition signal for igniting the hydrogen mixture in the combustion chamber, and a secondary discharge ignition signal for reducing the voltage of the secondary coil during the intake stroke compared to the voltage of the secondary coil at the end of the discharge. Effect of the Invention

[0007] According to the present invention, backfire in an engine caused by unintended spark discharge at a spark plug can be prevented at low cost without generating a positive voltage when charging an ignition coil. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an overall configuration diagram showing an example of the configuration of a spark ignition type hydrogen engine according to one embodiment of the present invention, which is a diagram showing an example of the configuration of a mono-fuel spark ignition type hydrogen engine that mixes hydrogen and air and burns them. [Diagram 2]FIG. 1 is a diagram showing another example of the configuration of a spark ignition hydrogen engine according to an embodiment of the present invention, and is a diagram showing an example of the configuration of a dual-fuel spark ignition hydrogen engine that mixes hydrogen, a fuel other than hydrogen, and air and burns them. [Diagram 3] 1 is a block diagram showing an example of the configuration of a control device (ECU) according to an embodiment of the present invention. [Figure 4] 1 is a circuit diagram showing an example of the configuration of an ignition device according to an embodiment of the present invention; [Diagram 5] FIG. 1 is an explanatory diagram showing ignition control according to the conventional technology and the operation and function of an ignition device 50, in which (a) shows an ignition signal 59 sent from an ECU 2 to an ignition device 50, (b) shows the primary current flowing through a primary coil 52, (c) shows the electromagnetic energy stored in the primary coil 52 and the secondary coil 53, (d) shows the secondary current flowing through a secondary coil 53, and (e) shows the time series change in the secondary voltage applied to an ignition plug 40. [Figure 6] FIG. 1 is an explanatory diagram illustrating problems with hydrogen engines using conventional technology, in which (a) is the lift amount of the intake valve 32 and exhaust valve 34 of the engine, (b) is the ignition signal 59 sent from the ECU 2 to the ignition device 50, (c) is the electromagnetic energy stored in the primary coil 52 and secondary coil 53, (d) is the secondary voltage applied to the spark plug 40, (e) is the pressure in the combustion chamber 37 (cylinder pressure), (f) is the amount of combustible mixture in the combustion chamber 37, and (g) is a diagram showing the time series change in the gas flow strength in the combustion chamber 37. [Figure 7] This is a characteristic diagram in which the breakdown voltage of hydrogen is calculated using Paschen's law versus the product p·d of pressure p and electrode gap d. [Figure 8] FIG. 1 is an explanatory diagram showing the ignition control by the ECU 2 and the operation and function of the ignition device 50 according to one embodiment of the present invention, in which (a) is the lift amount of the intake valve 32 and the exhaust valve 34 of the engine, (b) is the ignition signal 59 sent from the ECU 2 to the ignition device 50, (c) is the electromagnetic energy stored in the primary coil 52 and the secondary coil 53, (d) is the secondary voltage applied to the spark plug 40, (e) is the pressure in the combustion chamber 37 (in-cylinder pressure), (f) is the amount of combustible mixture in the combustion chamber 37, and (g) is a diagram showing the time series change in the gas flow strength in the combustion chamber 37. [Figure 9] FIG. 11 is a characteristic diagram showing the effect of an embodiment of the present invention, and is a diagram showing actual measurement results of open circuit voltage during the intake stroke in the conventional technology and the embodiment of the present invention. [Figure 10] FIG. 1 is a characteristic diagram showing the relationship between the secondary discharge timing and the open-circuit voltage during the intake stroke in one embodiment of the present invention, and is a diagram showing the actual measurement results of the open-circuit voltage during the intake stroke when the secondary discharge timing is changed from 30° CA after the compression top dead center to 180° CA. [Figure 11] FIG. 4 is a characteristic diagram showing the relationship between the open-circuit voltage before and after secondary discharge according to an embodiment of the present invention. [Figure 12] FIG. 1 is a characteristic diagram showing the relationship between the secondary discharge charge period (the ON period of the secondary discharge ignition signal) and the open circuit voltage during the intake stroke according to an embodiment of the present invention, and shows actual measurement results of the open circuit voltage during the intake stroke when the secondary discharge period is changed from 2% (the ratio to the ON period of the main discharge ignition signal) to 100% (the ratio to the ON period of the main discharge ignition signal). [Figure 13] 5 is a flowchart showing a procedure for performing secondary discharge based on load information according to an embodiment of the present invention. [Figure 14] 11A and 11B are explanatory diagrams showing an example of changing the charging period when secondary discharging is performed and when secondary discharging is avoided according to an embodiment of the present invention. [Figure 15] FIG. 4 is an explanatory diagram showing the relationship between the charging time and the breakdown voltage of an ignition coil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In this specification and the accompanying drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0010] [Configuration of a spark ignition hydrogen engine] First, the configuration of a spark ignition hydrogen engine according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram showing an example of the configuration of a spark ignition type hydrogen engine according to an embodiment of the present invention. As shown in FIG. 1, the spark ignition hydrogen engine 1 includes a cylinder 38, a piston 35 that slides inside the cylinder 38, an intake valve 32, an exhaust valve 34, and an ignition plug 40. A combustion chamber 37 facing the piston 35 is formed in the cylinder 38. The combustion chamber 37 communicates with the intake manifold 31 and the exhaust manifold 33.

[0011] An electronically controlled throttle valve 39 is provided in the intake manifold 31. The electronically controlled throttle valve 39 is set to a predetermined opening by a throttle valve drive signal 58 sent from a control device (ECU: Electric Control Unit) 2, and adjusts the amount of air flowing into the combustion chamber 37. The control device 2 will be referred to as ECU 2 in the following description.

[0012] The intake valve 32 opens and closes communication between the intake manifold 31 and the combustion chamber 37. The exhaust valve 34 opens and closes communication between the exhaust manifold 33 and the combustion chamber 37. The intake manifold 31 is provided with an injector 36 that injects hydrogen. The amount of hydrogen injected by the injector 36 is adjusted by an injector drive signal 57 sent from the ECU 2. A mixture of the hydrogen injected by the injector 36 and the air taken in from the intake manifold 31 is supplied to the combustion chamber 37.

[0013] The intake valve 32 is equipped with a variable valve timing mechanism (VVT) 29, and the exhaust valve 34 is equipped with a variable valve timing mechanism 30. The variable valve timing mechanisms 29, 30 are referred to as VVT 29, 30 in the following description. The VVT ​​29 adjusts the opening and closing timing of the intake valve 32 by an intake VVT ​​drive signal 60 sent from the ECU 2. The VVT ​​30 adjusts the opening and closing timing of the exhaust valve 34 by an exhaust VVT drive signal 61 sent from the ECU 2.

[0014] The spark ignition hydrogen engine 1 is equipped with various sensors, not shown, such as a water temperature sensor, an oil temperature sensor, an oil pressure sensor, a knock sensor, an intake air volume sensor, an air-fuel ratio sensor, a crank angle sensor, a throttle opening sensor, an accelerator opening sensor, etc. Using these sensors, the spark ignition hydrogen engine 1 obtains information such as engine coolant temperature, oil temperature, oil pressure, knock intensity, intake air volume, air-fuel ratio, crank angle, throttle opening, and accelerator opening, and inputs this information to the ECU 2.

[0015] The spark ignition hydrogen engine 1 also includes an ignition device 50. The ignition device 50 is connected to a spark plug by a high tension cord 48, and applies a high voltage to the spark plug 40. When the high voltage is applied from the ignition device 50 to the spark plug 40, a spark discharge occurs in the gap of the spark plug 40. The timing at which the ignition device 50 applies the high voltage to the spark plug 40 is adjusted by an ignition signal 59 sent from the ECU 2 to the ignition device 50.

[0016] When a spark discharge occurs in the gap of the spark plug 40, the air-fuel mixture in the combustion chamber 37 is ignited and combusted. The air-fuel mixture combusted in the combustion chamber 37 pushes down the piston 35, rotating a crankshaft (not shown). As a result, the power generated by the combustion in the spark ignition hydrogen engine 1 is output to the outside.

[0017] The spark ignition hydrogen engine 1 is a four-stroke engine, and while a crankshaft (not shown) rotates 720° (two revolutions), each of the intake, compression, expansion, and exhaust strokes is performed at 180° CA (crank angle). The spark ignition hydrogen engine 1 is a so-called mono-fuel spark ignition hydrogen engine that burns a mixture of hydrogen and air, but the spark ignition hydrogen engine according to one embodiment of the present invention may also be configured to mix hydrogen with a fuel other than hydrogen. 2 includes an injector 36a that injects a second fuel other than hydrogen, in addition to the injector 36 that injects hydrogen, in the intake manifold 31. The amount of the second fuel injected by the injector 36a is adjusted by an injector drive signal 57a sent from the ECU 2.

[0018] A mixture of hydrogen injected by the injector 36, a second fuel injected by the injector 36a, and air taken in from the intake manifold 31 is supplied to the combustion chamber 37. In other words, the spark ignition hydrogen engine 1a forms a so-called multi-fuel spark ignition hydrogen engine that mixes and burns hydrogen, a second fuel other than hydrogen, and air. As the second fuel other than hydrogen, for example, liquid fuels such as gasoline, diesel, ethanol, methanol, synthetic fuel (eFuel), and gas fuels such as natural gas, propane, and ammonia are used.

[0019] [ECU configuration] Next, a configuration example of the control device (ECU) 2 according to an embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing an example of the configuration of the ECU 2. 3, the ECU 2 has an input circuit 3, an input / output port 4, a RAM (Random Access Memory) 5, a ROM (Read Only Memory) 6, and a CPU (Central Processing Unit) 7. The ECU 2 also has an ignition control unit 10, a valve timing control unit 11, an air control unit 12, and a fuel control unit 13.

[0020] The input circuit 3 receives output values ​​from various sensors such as water temperature, oil temperature, oil pressure, intake air volume, intake pressure, intake temperature, humidity, crank angle, throttle opening, accelerator opening, accelerator position, air-fuel ratio, and knock intensity. The input circuit 3 performs processing such as noise removal on the input signal and then sends it to the input / output port 4. The value input to the input port of the input / output port 4 is stored in the RAM 5. The ROM 6 stores a control program describing the contents of various arithmetic processing executed by the CPU 7, as well as maps and data tables used in each process.

[0021] The RAM 5 is provided with a storage area for storing values ​​input to the input ports of the input / output port 4, and values ​​representing the operation amounts of each actuator and the state of the engine (e.g., knock state, etc.) calculated according to the control program. The operation amounts of each actuator and the values ​​representing the state of the engine stored in the RAM 5 are sent to the output ports of the input / output port 4.

[0022] The ignition control unit 10 receives sensor output values, operation amounts of each actuator, and engine state values ​​from the input / output port 4 , and outputs an ignition signal 59 to the ignition device 50 . The valve timing control unit 11 receives the sensor output values, the operation amounts of each actuator, and the engine state values ​​from the input / output port 4, and outputs an intake VVT ​​drive signal 60 to the intake VVT ​​29. The valve timing control unit 11 also outputs an exhaust VVT drive signal 61 to the exhaust VVT 30.

[0023] The air control unit 12 receives sensor output values, operation amounts of each actuator, and engine state values ​​from the input / output port 4 , and outputs a throttle valve drive signal 58 to the throttle valve 39 . The fuel control unit 13 receives sensor output values, operation amounts of each actuator, and engine state values ​​from the input / output port 4, and outputs an injector drive signal 57 to the injector 36. In addition, the fuel control unit 13 outputs an injector drive signal 57a to the injector 36a.

[0024] [Ignition device configuration] Next, the configuration of an ignition device 50 according to an embodiment of the present invention will be described with reference to FIG. FIG. 4 is a circuit diagram showing an example of the configuration of the ignition device 50. As shown in FIG. The ignition device 50 includes a primary coil 52 through which a primary current is passed, an igniter 54, and a secondary coil 53. The igniter 54 passes a primary current through the primary coil 52 when an ignition signal 59 supplied from the ECU 2 is turned on, and cuts off the primary current when the ignition signal 59 is turned off. The secondary coil 53 outputs to the spark plug 40 a secondary current that is generated when the igniter 54 cuts off the primary current. A voltage of, for example, +12 V from a battery (not shown) is applied to the primary coil 52, causing a primary current to flow through the primary coil 52. The ratio of the number of turns of the secondary coil 53 to the primary coil 52 is set to, for example, about 100.

[0025] On the other hand, one end of the secondary coil 53 is connected to the spark plug 40, and the other end of the secondary coil 53 is connected to the anode of a diode 55. The cathode of the diode 55 is grounded via a resistor 56. When the ignition signal 59 supplied from the ECU 2 is turned off, the primary current flowing through the igniter 54 is cut off. At this time, a magnetic field change occurs in the primary coil 52, and a primary voltage is generated by self-induction. Furthermore, a high secondary voltage according to the turn ratio is generated by mutual induction in the secondary coil 53, which shares a magnetic circuit and magnetic flux with the primary coil 52. The secondary voltage is then applied to the spark plug 40, and a spark discharge occurs in the gap 41. Furthermore, a secondary current generated by the secondary voltage being induced in the secondary coil 53 flows through the diode 55 and resistor 56.

[0026] The polarity is reversed between the primary and secondary sides of the ignition coil, and the current and voltage directions are reversed. In this specification, a high secondary voltage means that the absolute value of the negative secondary voltage is large. A low secondary voltage means that the absolute value of the negative secondary voltage is small.

[0027] [Operation and function of ignition control and ignition device according to conventional technology] Next, ignition control according to the conventional technology and the operation and function of the ignition device 50 will be described with reference to Fig. 5. Here, the example shown in Fig. 5 shows a technology in which an ignition signal 59 is sent from an ECU 2 to the ignition device 50 once during one engine cycle (two rotations of the crankshaft). Also, the example shown in Fig. 5 is a technology in which a bypass resistance element for returning residual energy on the secondary side of the ignition coil to a power source is not provided. The bypass resistance element refers to a resistance element between the primary side and secondary side of the ignition coil.

[0028] Fig. 5 is an explanatory diagram showing the operation and function of ignition control and ignition device 50 according to the conventional technology. Fig. 5(a) shows the time series change of ignition signal 59 sent from ECU 2 to ignition device 50, and Fig. 5(b) shows the time series change of primary current flowing through primary coil 52. Fig. 5(c) shows the time series change of electromagnetic energy stored in primary coil 52 and secondary coil 53, and Fig. 5(d) shows the time series change of secondary current flowing through secondary coil 53. Fig. 5(e) shows the time series change of secondary voltage applied to ignition plug 40.

[0029] 5, an ignition signal 59 is normally sent from the ECU 2 to the ignition device 50 at the end of the compression stroke (approximately 20° CA before top dead center of compression) in order to ignite the mixture in the combustion chamber 37. When the ignition signal 59 is turned on (when it rises from 0 V to 5 V), a primary current flows and electromagnetic energy is stored in the primary coil. That is, the period during which the ignition signal 59 is on corresponds to the charging period of the ignition coil. When the ignition signal 59 is turned off and the primary current is cut off, a high voltage is generated in the secondary coil 53 due to mutual induction between the primary coil 52 and the secondary coil 53, and a spark discharge occurs in the gap 41 of the spark plug 40. This spark discharge then ignites the air-fuel mixture in the combustion chamber 37, and power is taken from the engine as the air-fuel mixture is burned.

[0030] In this way, the electromagnetic energy stored in the coil is released into the air-fuel mixture by the spark discharge, so the amount of electromagnetic energy (c) stored in the ignition coil decreases. The discharge path (arc) formed in the gap 41 of the spark plug 40 is elongated (discharge path elongation occurs) by the gas flow in the combustion chamber 37, increasing the electrical resistance of the gap 41. This increases the breakdown voltage of the gap 41, and when the breakdown voltage becomes higher than the secondary voltage, the spark discharge is interrupted.

[0031] For this reason, the electromagnetic energy stored in the coil during the charging period is not entirely consumed by the spark discharge, and approximately 1 / 20 of the amount of electromagnetic energy stored in the coil during the charging period remains in the coil even after the expansion stroke. This energy remaining in the coil is called residual energy. In addition, the resistance of the discharge path increases due to the extension of the discharge path, so the secondary voltage rises at the end of the spark discharge.Then, the spark discharge is cut off with the secondary voltage raised, so a relatively high open circuit voltage is maintained on the secondary side of the coil.

[0032] [Issues with spark ignition hydrogen engines] Next, referring to FIG. 6, the problems in the conventional spark ignition hydrogen engine shown in FIG. 5 will be described. FIG. 6 is an explanatory diagram showing the problems in the conventional spark ignition hydrogen engine. FIG. 6(a) shows the time series change in the lift amount of the intake valve 32 and the exhaust valve 34 of the spark ignition hydrogen engine, and FIG. 6(b) shows the time series change in the ignition signal 59 sent from the ECU 2 to the ignition device 50. FIG. 6(c) shows the time series change in the electromagnetic energy stored in the primary coil 52 and the secondary coil 53, and FIG. 6(d) shows the time series change in the secondary voltage applied to the spark plug 40. FIG. 6(e) shows the time series change in the pressure (cylinder pressure) in the combustion chamber 37, FIG. 6(f) shows the time series change in the combustible mixture concentration in the combustion chamber 37, and FIG. 6(g) shows the time series change in the gas flow strength in the combustion chamber 37.

[0033] As described above, in the conventional technology, the ignition coil has a relatively large amount of residual energy even after the spark discharge caused by the ignition signal 59 sent from the ECU 2 to the ignition device 50. In addition, at the timing of the spark discharge caused by the ignition signal 59 sent to the ignition device 50 (the end of the compression stroke), the gas flow in the cylinder is relatively strong as shown in Fig. 6(g). Therefore, the discharge path is expanded by this gas flow, and the open-circuit voltage of the secondary coil after the spark discharge is interrupted (hereinafter, simply referred to as the open-circuit voltage) becomes high.

[0034] On the other hand, the in-cylinder pressure of a spark-ignition hydrogen engine decreases from the expansion stroke to the exhaust stroke and then to the intake stroke, as shown in FIG. 6(e). It is generally known that the magnitude of the breakdown voltage depends on the pressure, and the lower the pressure, the lower the breakdown voltage. Therefore, the breakdown voltage of the gap 41 of the spark plug 40 is the lowest during the intake stroke. Then, when the breakdown voltage during the intake stroke becomes lower than the open voltage, a natural discharge (spark discharge without ignition signal 59) occurs in the gap 41. This natural discharge releases the residual energy of the ignition coil into the air-fuel mixture.

[0035] During the intake stroke, a mixture of air and hydrogen (or air, hydrogen, and a second fuel other than hydrogen) formed in the intake manifold 31 is drawn into the combustion chamber 37. This results in a high combustible mixture concentration in the cylinder, as shown in FIG. 6(f). Also, a hydrogen mixture (or a mixture of hydrogen and a second fuel other than hydrogen) is ignited with extremely small ignition energy compared to mixtures of other fuels that do not contain hydrogen, such as gasoline, natural gas, and ammonia. In other words, it is known that the combustible mixture concentration range is significantly wider than other fuels that do not contain hydrogen.

[0036] The amount of energy released into the mixture by natural discharge is almost equal to the amount of residual energy in the coil. This is approximately 1 / 20th of the energy released into the mixture by the spark discharge that occurs at the end of the compression stroke. For this reason, natural discharge is unlikely to lead to ignition in a mixture of fuels that do not contain hydrogen. However, as mentioned above, a hydrogen mixture (or a mixture of hydrogen and a second fuel other than hydrogen) is highly ignitable and has a wide range of flammable concentrations, so it easily ignites due to natural discharge during the intake stroke and explodes. This explosion is an abnormal combustion called a backfire, and there is a risk of causing serious damage to the engine.

[0037] In this way, energy that would be sufficient to ignite the hydrogen mixture remains in the ignition coil, and natural discharge occurs during the intake stroke, which is one of the causes of backfire in spark-ignition hydrogen engines.

[0038] [Target open circuit voltage during intake stroke of hydrogen engine] To prevent flashback in a spark ignition hydrogen engine, it is effective to keep the open circuit voltage during the intake stroke of the spark ignition hydrogen engine lower than the breakdown voltage of the ignition gap and prevent spontaneous discharge from occurring in the ignition gap. It is known that Paschen's law holds true between the breakdown voltage and the product of pressure and electrode gap. Figure 7 is a characteristic diagram in which the breakdown voltage of hydrogen (vertical axis) is calculated using Paschen's law against the product p·d (horizontal axis) of pressure p and electrode gap d. If the open circuit voltage during the intake stroke is made lower than the breakdown voltage of hydrogen shown in Figure 7, it is possible to prevent spontaneous discharge in the ignition gap.

[0039] In a typical spark ignition hydrogen engine, the range of p·d at which flashback occurs is approximately 12 to 36 mPa (intake pressure p = 20 to 60 kPa, electrode gap d = 0.6 mm). The horizontal axis of Fig. 6 shows p·d in units of [cm·Torr]. Therefore, the breakdown voltage during the intake stroke of a spark ignition hydrogen engine is thought to be about 0.5 to 1 kV, as shown in Figure 7. That is, to prevent flashback due to natural discharge in a spark ignition hydrogen engine, the open circuit voltage during the intake stroke must be kept below 1 kV. Furthermore, to prevent flashback due to natural discharge in a spark ignition hydrogen engine, it is more desirable to keep the open circuit voltage during the intake stroke below 0.5 kV.

[0040] [Operation and function of ignition control and ignition device in one embodiment of the present invention] Next, with reference to FIG. 8, the operation and function of the ignition control and device according to one embodiment of the present invention will be described. Fig. 8 is an explanatory diagram showing the ignition control by the ECU 2 and the operation and function of the ignition device 50 according to one embodiment of the present invention. Fig. 8(a) shows the time series change in the lift amount of the intake valve 32 and the exhaust valve 34 of the engine, and Fig. 8(b) shows the time series change in the ignition signal 59 sent from the ECU 2 to the ignition device 50. Fig. 8(c) shows the time series change in the electromagnetic energy stored in the primary coil 52 and the secondary coil 53, and Fig. 8(d) shows the time series change in the secondary voltage applied to the spark plug 40. Fig. 8(e) shows the time series change in the pressure (cylinder pressure) in the combustion chamber 37, Fig. 8(f) shows the time series change in the amount of combustible mixture in the combustion chamber 37, and Fig. 8(g) shows the time series change in the gas flow strength in the combustion chamber 37.

[0041] In one embodiment of the present invention, in order to ignite the mixture in the combustion chamber 37, an ignition signal (main discharge ignition signal) is usually sent from the ECU 2 to the ignition device 50 at the end of the compression stroke. When the main discharge ignition signal is turned on (when it rises from 0V to 5V), a primary current flows and electromagnetic energy is stored in the primary coil. That is, the period during which the main discharge ignition signal is on corresponds to the charging period for the main discharge of the ignition coil. When the main discharge ignition signal is turned off and the primary current is cut off, a high voltage is generated in the secondary coil 53 due to mutual induction between the primary coil 52 and the secondary coil 53. When the secondary voltage becomes higher than the dielectric breakdown voltage of the gap 41 of the spark plug, a spark discharge (main discharge) occurs in the gap 41 of the spark plug. This main discharge ignites the mixture in the combustion chamber 37, and power is taken out of the engine by the combustion of the mixture.

[0042] Since the electromagnetic energy stored in the ignition coil is released into the air-fuel mixture by the main discharge, the amount of electromagnetic energy stored in the ignition coil decreases. The discharge path (arc) formed in the gap 41 of the spark plug 40 is stretched by the gas flow in the engine combustion chamber 37, increasing the electrical resistance of the gap 41. This causes the breakdown voltage of the gap 41 to rise, and when the breakdown voltage becomes higher than the secondary voltage, the main discharge is shut off. For this reason, the electromagnetic energy stored in the ignition coil during the charging period is not entirely consumed by the main discharge, but remains in the ignition coil as residual energy even after the main discharge ends. In addition, because the main discharge is shut off due to the rise in breakdown voltage caused by the stretching of the discharge path, a relatively high open circuit voltage is maintained.

[0043] Next, in the middle of the expansion stroke following the main discharge (for example, 60° CA after top dead center of compression), an ignition signal (secondary discharge ignition signal) is sent from the ECU 2 to the ignition device 50. When the secondary discharge ignition signal turns on (rises from 0V to 5V), a primary current flows and electromagnetic energy is stored in the primary coil. In other words, the period during which the secondary discharge ignition signal is on corresponds to the charging period for secondary discharge of the ignition coil. Due to charging for secondary discharge, the amount of energy (c) in the ignition coil becomes the sum of the residual energy amount from the main discharge and the amount of energy stored in association with charging for secondary discharge.

[0044] When the secondary discharge ignition signal is turned off and the primary current is cut off, a high voltage is generated in the secondary coil 53 due to mutual induction between the primary coil 52 and the secondary coil 53. When the secondary voltage becomes higher than the breakdown voltage of the spark plug gap 41, a spark discharge (secondary discharge) occurs in the spark plug gap 41. In the middle of the expansion stroke following the main discharge (for example, 60° CA after top dead center of compression), the fuel concentration in the mixture is very low due to combustion, so the mixture does not ignite due to the secondary discharge.

[0045] Furthermore, since the gas flow strength (g) in the cylinder becomes relatively weak in the middle of the expansion stroke (for example, 60° CA after top dead center of compression), the extension of the discharge path formed in the gap 41 of the spark plug 40 by the secondary discharge is smaller than the extension of the discharge path formed in the gap 41 of the spark plug 40 by the main discharge. Therefore, the electrical resistance value of the discharge path at the end of the secondary discharge is smaller than the electrical resistance value of the discharge path at the end of the main discharge.

[0046] Furthermore, the cylinder pressure in the middle of the expansion stroke (e.g., 60° CA after compression top dead center) is lower than the cylinder pressure at the end of the compression stroke where the main discharge is performed (e.g., 20° CA before compression top dead center). Therefore, the breakdown voltage in the middle of the expansion stroke (e.g., 60° CA after compression top dead center) is lower than the breakdown voltage at the end of the compression stroke where the main discharge is performed (e.g., 20° CA before compression top dead center).

[0047] That is, at the end of the secondary discharge, the electrical resistance of the discharge path is small and the breakdown voltage is low, so the open-circuit voltage after the secondary discharge is interrupted is lower than the open-circuit voltage immediately after the main discharge is interrupted. Also, since the secondary discharge proceeds to an open-circuit voltage lower than that of the main discharge, the residual energy amount immediately after the secondary discharge is smaller than that immediately after the main discharge.

[0048] [Effects of one embodiment of the present invention] Next, the differences in operation and effect between the prior art and one embodiment of the present invention will be described with reference to FIG. Fig. 9 is a characteristic diagram showing the difference in open circuit voltage during the intake stroke between the conventional technology and an embodiment of the present invention. That is, Fig. 9 shows the actual measurement results of the open circuit voltage (vertical axis) at the start timing of the intake stroke for an example of the conventional technology and an embodiment of the present invention, arranged on the horizontal axis. In addition, the open circuit voltage at the start timing of the intake stroke varies depending on the engine cycle (cycle variation). Therefore, in the experiment, the open circuit voltage was measured over multiple engine cycles. Figure 9 shows the result of the cycle with the highest open circuit voltage in this experiment.

[0049] As shown in Figure 9, in the conventional technology, the open circuit voltage during the intake stroke exceeds 0.5 kV, which is the minimum breakdown voltage in a spark ignition hydrogen engine. In contrast, in one embodiment of the present invention, the open circuit voltage during the intake stroke can be made lower than 0.5 kV, which is the minimum breakdown voltage in a spark ignition hydrogen engine. As a result, in one embodiment of the present invention, no natural discharge occurs in gap 41 of spark plug 40 during the intake stroke, making it possible to prevent flashback in a spark ignition hydrogen engine caused by natural discharge.

[0050] Furthermore, in one embodiment of the present invention, there is no need to provide a bypass resistor for releasing residual energy between primary coil 52 and secondary coil 53 of ignition device 50. Therefore, in one embodiment of the present invention, backfire in a spark-ignition hydrogen engine caused by unintended discharge at the spark plug can be prevented at low cost without generating a positive voltage when the ignition coil is charged.

[0051] [Relationship between secondary discharge timing and open circuit voltage during intake stroke] Next, with reference to FIG. 10, a relationship between the secondary discharge timing and the open circuit voltage during the intake stroke according to one embodiment of the present invention will be described. Fig. 10 is a characteristic diagram showing the relationship between the secondary discharge timing (horizontal axis) and the open circuit voltage (vertical axis) during the intake stroke (timing at the start of the intake stroke) in one embodiment of the present invention. That is, Fig. 10 shows the actual measurement results of the open circuit voltage during the intake stroke when the secondary discharge timing is changed from 30° CA after the compression top dead center to 180° CA. In the example of Fig. 10, the secondary discharge charging period is constant. As mentioned above, the open-circuit voltage varies from cycle to cycle, so Fig. 10 shows the results for the cycle in which the open-circuit voltage was highest at each secondary discharge timing. Note that the secondary discharge timing is the timing at which the secondary discharge ignition signal goes from on to off (5V to 0V).

[0052] As shown in Figure 10, the open circuit voltage during the intake stroke depends on the timing of the secondary discharge. In order to keep the open circuit voltage during the intake stroke at or below 0.5 kV, which is the minimum dielectric breakdown voltage in a spark ignition hydrogen engine, it is desirable to set the timing of the secondary discharge in the range of 60° CA after compression top dead center to exhaust valve opening timing (Exhaust Valve Opening: EVO) + 10° CA.

[0053] The reason that the open circuit voltage in the intake stroke becomes high when the secondary discharge timing is set to the end of the expansion stroke (after EVO+10° CA) is that the gas flow in the cylinder becomes stronger at the secondary discharge timing. As shown in Fig. 6(g), the strength of the gas flow in the cylinder becomes stronger after 10° CA from EVO. This is because pressurized gas in the cylinder flows out to the exhaust manifold 33 as the exhaust valve opens. When the gas flow in the cylinder is strong, the discharge path extension of the secondary discharge increases, increasing the open circuit voltage after the secondary discharge, and this high open circuit voltage is maintained until the intake stroke.

[0054] In addition, the reason why the open circuit voltage in the intake stroke becomes high when the secondary discharge timing is set to the early stage of the expansion stroke (for example, 30° CA after the compression top dead center) is because the open circuit voltage is high at the secondary discharge timing. That is, as shown in Fig. 5(e), the open-circuit voltage is highest after the main discharge and tends to decrease over time. This is because the charge remaining in the ignition coil leaks out through the high-tension cable and the spark plug.

[0055] Therefore, if the secondary discharge is timed early in the expansion stroke (for example, 30° CA after top dead center of compression), the open circuit voltage at the timing of the secondary discharge will be higher than if the secondary discharge is timed later than the beginning of the compression stroke (for example, 60° CA after top dead center of compression). Also, as shown in Fig. 11, there is a linear correlation between the open-circuit voltage before the secondary discharge (horizontal axis) and the open-circuit voltage after the secondary discharge (vertical axis). Therefore, if the open-circuit voltage at the timing of the secondary discharge is high, the open-circuit voltage after the secondary discharge also becomes high. Another factor that causes the open-circuit voltage after the secondary discharge to become high is that the gas flow inside the cylinder becomes strong at the beginning of the expansion stroke (for example, 30° CA after the compression top dead center), which increases the extension of the discharge path of the secondary discharge.

[0056] [Relationship between secondary discharge charge period and open circuit voltage during intake stroke] Next, with reference to FIG. 12, a relationship between the secondary discharge charge period and the open circuit voltage during the intake stroke according to one embodiment of the present invention will be described. Fig. 12 is a characteristic diagram showing the relationship between the secondary discharge charge period (on period of the secondary discharge ignition signal: horizontal axis) and the open circuit voltage (vertical axis) during the intake stroke (intake stroke start timing) according to one embodiment of the present invention. That is, Fig. 12 shows the actual measurement results of the open circuit voltage during the intake stroke (intake stroke start timing) when the secondary discharge charge period is changed from 2% (ratio to the main discharge charge period) to 100% (ratio to the main discharge charge period). In the example of Fig. 12, the secondary discharge charge period is constant. As mentioned above, the open circuit voltage varies from cycle to cycle, so the results for the cycle with the highest open circuit voltage for each secondary discharge charging period are shown in Figure 12. The main discharge charging period is the period during which the main discharge ignition signal is on.

[0057] As shown in Figure 12, the open circuit voltage during the intake stroke depends on the secondary discharge charge period. Therefore, when the secondary discharge charge period is 40% or less, the open circuit voltage during the intake stroke increases as the secondary discharge charge period decreases. This is because the secondary voltage (so-called breakdown voltage) generated at the beginning of discharge decreases when the secondary discharge charge period decreases, making the secondary discharge unstable. In other words, if the secondary discharge charging period is reduced, secondary discharges will not occur or will be cut off early, reducing or eliminating the effect of secondary discharge in reducing the open circuit voltage. For this reason, it is desirable to set the secondary discharge charging period to 5% or more (as a ratio to the main discharge charging period). If the secondary discharge charging period is set to 5% or more, the open circuit voltage during the intake stroke can be reduced to 0.5 kV or less, which is the minimum value of the dielectric breakdown voltage in a spark ignition hydrogen engine, and natural discharge during the intake stroke can be prevented.

[0058] In addition, when the secondary discharge charging period exceeds 40% (ratio to the main discharge charging period), the open circuit voltage becomes almost constant even if the secondary discharge charging period changes. This is because when the secondary discharge charging period exceeds 40% (ratio to the main discharge charging period), the secondary discharge becomes stable and the effect of reducing the open circuit voltage by the secondary discharge becomes almost constant. For this reason, it is more desirable to set the secondary discharge charging period in the range of 5% to 40% (ratio to the main discharge charging period). In other words, if the secondary discharge charging period is set in the range of 5% to 40% (ratio to the main discharge charging period), it is possible to prevent natural discharge during the intake stroke and to prevent excessive energy release during the secondary discharge. This has the advantages of extending the life of the spark plug 40 (reducing electrode wear), improving reliability by reducing heat generation in the ignition device 50, and reducing energy consumption.

[0059] [Secondary discharge based on engine load information] Whether or not spark discharge occurs during the intake stroke, which is one of the causes of backfire in spark-ignition hydrogen engines, varies depending on the state of the engine and the environmental conditions. For example, whether or not spark discharge occurs during the intake stroke varies depending on factors such as low engine load, low air-fuel ratio (fuel rich), low EGR (Exhaust Gas Recirculation) rate, and small spark plug gap (less electrode wear). In addition, when the environmental temperature is high, spark discharge is more likely to occur during the intake stroke compared to when the environmental temperature is low, depending on engine conditions such as high engine load, high air-fuel ratio (fuel lean), high EGR rate, and large spark plug gap (more electrode wear).

[0060] Therefore, the implementation and avoidance of secondary discharge may be switched based on the engine state and environmental state. That is, when there is a high possibility of spark discharge occurring during the intake stroke, secondary discharge may be implemented. On the other hand, when there is a low possibility of spark discharge occurring during the intake stroke, secondary discharge may be avoided. In this way, by switching between implementation and avoidance of discharge based on the engine state and environmental conditions, the number of secondary discharges during the engine operation period can be reduced. This has the advantages of extending the life of the spark plug (reducing electrode wear), improving reliability by reducing heat generation in the ignition device, and reducing energy consumption. For example, secondary discharge may be switched between being performed and being avoided based on engine load information.

[0061] FIG. 13 is a flowchart showing a procedure for performing secondary discharge based on engine load information according to one embodiment of the present invention. 13, the ECU 2 sends an ignition signal (main discharge ignition signal) to the ignition device 50 at the end of the compression stroke to perform main discharge (step S1). Next, the ECU 2 compares the current load factor with a predetermined load factor threshold value Lc (e.g., 20%) (step S2). If the current load factor is smaller than the threshold value Lc in step S2 (if Yes), the ECU 2 sends a secondary discharge ignition signal to the ignition device 50 in the expansion stroke following the main discharge to perform secondary discharge (step S3). On the other hand, if the current load factor is not smaller than the threshold value Lc in step S2 (if No), the ECU 2 avoids sending the secondary discharge ignition signal in this engine cycle and updates to the next engine cycle (step S4).

[0062] Switching between implementing and avoiding secondary discharge based on engine load information in this manner has the following advantages. Natural discharge during the intake stroke, which can cause backfire in a spark ignition hydrogen engine, occurs when the in-cylinder pressure is low and the breakdown voltage is low. Therefore, by implementing a secondary discharge when the load rate is low and the in-cylinder pressure during the intake stroke to lower the open circuit voltage below the breakdown voltage, backfire due to natural discharge can be prevented. On the other hand, when the load rate is high and the in-cylinder pressure during the intake stroke is high, the breakdown voltage becomes high and natural discharge is less likely to occur. Therefore, when the load rate is high, there is little risk of backfire occurring even if the open circuit voltage is not lowered by implementing a secondary discharge.

[0063] In this way, by switching between implementing and avoiding secondary discharge based on the engine load factor, it is possible to reduce the number of secondary discharges that occur while the engine is running, which has the advantages of extending the life of the spark plug (reducing electrode wear), improving reliability by reducing heat generation in the ignition device, and reducing energy consumption.

[0064] Also, the implementation and avoidance of secondary discharge may be switched based on information other than the engine load factor. For example, secondary discharge may be implemented when at least one of the various quantities correlated with the engine load, such as the throttle opening, torque, engine speed, intake pressure, in-cylinder pressure, intake air volume, exhaust gas flow rate, fuel flow rate, accelerator opening, load output (e.g., power generation amount, etc.), exhaust temperature, coolant volume, water temperature, and oil temperature, is smaller than a predetermined threshold value, and secondary discharge may be avoided when at least one of these quantities is not smaller than the predetermined threshold value.

[0065] Furthermore, in a multi-fuel spark ignition hydrogen engine, secondary discharge may be switched between being performed and being avoided based on the hydrogen ratio of the fuel. In a multi-fuel spark ignition hydrogen engine, flashback due to natural discharge is likely to occur when the hydrogen ratio of the fuel is high, and flashback due to natural discharge is unlikely to occur when the hydrogen ratio of the fuel is low. Therefore, in a multi-fuel spark ignition hydrogen engine, secondary discharge may be performed when the hydrogen ratio in the fuel is greater than a predetermined threshold (e.g., a heat value ratio of 50%), and secondary discharge may be avoided when the hydrogen ratio in the fuel is less than a predetermined threshold (e.g., a heat value ratio of 50%).

[0066] Furthermore, secondary discharge may be switched between being performed and being avoided based on a combination of various quantities correlated with the engine load and the hydrogen percentage in the fuel. For example, secondary discharge may be performed when the intake pressure is lower than the intake pressure threshold and the hydrogen percentage is higher than the hydrogen percentage threshold. Secondary discharge may be avoided when the intake pressure is not lower than the intake pressure threshold or when the hydrogen percentage is not higher than the hydrogen percentage threshold. This makes it possible to reduce the number of secondary discharges during the engine operation period, thereby enhancing the advantages of extending the life of the spark plug (reducing electrode wear), improving reliability by reducing heat generation in the ignition device, and reducing energy consumption. Also, the charging period of the main discharge (the on period of the main discharge ignition signal) may be changed when secondary discharge is performed and when it is avoided.

[0067] [Change in main discharge charging period when secondary discharge is performed and avoided] Fig. 14 is an explanatory diagram showing an example of changing the charging period when secondary discharge is performed and when it is avoided according to one embodiment of the present invention. Fig. 14(a) shows the time series change of the discharge signal when secondary discharge is performed, and Fig. 14(b) shows the time series change of the discharge signal when secondary discharge is avoided. Here, the time when secondary discharge is performed refers to an engine cycle when an ignition signal (ON signal) for secondary discharge is sent to the ignition device 50. Also, the time when secondary discharge is avoided refers to an engine cycle when sending an ignition signal (ON signal) for secondary discharge to the ignition device 50 is avoided.

[0068] In a method of changing the charging period when secondary discharge is performed and when it is avoided according to an embodiment of the present invention, the charging period of the main discharge when secondary discharge is performed (on period of the ignition signal for main discharge) shown in Fig. 14(a) is made shorter than the charging period of the main discharge when secondary discharge is avoided (on period of the ignition signal for main discharge) shown in Fig. 14(b). Note that, as shown in Fig. 15, there is a positive correlation between the charging period of the ignition coil (on period of the ignition signal: horizontal axis) and the secondary voltage at the beginning of discharge (so-called breakdown voltage: vertical axis). Therefore, if the charging period of the ignition coil is too short, the breakdown voltage becomes lower than the dielectric breakdown voltage and no spark discharge occurs. Therefore, in a method of changing the charging period when a secondary discharge is performed and when it is avoided according to an embodiment of the present invention, when the charging period of the main discharge when a secondary discharge is performed is made shorter than the charging period of the main discharge when a secondary discharge is avoided, the charging time of the main discharge is shortened to the extent that the breakdown voltage exceeds the dielectric breakdown voltage.

[0069] In this way, by making the charging period of the main discharge when secondary discharge is performed shorter than the charging period of the main discharge when secondary discharge is avoided, it is possible to reduce the ignition coil energy when secondary discharge is performed. This makes it possible to further enhance the advantages of extending the life of the spark plug 40 (reducing electrode wear), improving reliability by reducing heat generation in the ignition device 50, and reducing energy consumption. In addition, the combined charging period of the main discharge when secondary discharge is performed and the charging period of the secondary discharge is approximately the same as the charging period of the main discharge when secondary discharge is avoided, making it possible to prevent the secondary discharge from having an adverse effect on the life of the spark plug 40 and on the heat generation of the ignition device 50. [Explanation of symbols]

[0070] 1...spark ignition hydrogen engine, 1a...mixed-fuel spark ignition hydrogen engine, 2...ECU (Electronic Control Unit), 3...input / output circuit, 4...input / output port, 5...RAM (Random Access Memory), 6...ROM (Read Only Memory), 7...CPU (Central Processing Unit), 10...ignition control unit, 11...valve timing control unit, 12...air control unit, 13...fuel control unit, 29...intake VVT ​​(Variable Valve Timing), 30...Exhaust VVT, 31...Intake manifold, 32...Intake valve, 33...Exhaust manifold, 34...Exhaust valve, 35...Piston, 36, 36a...Injector, 37...Combustion chamber, 38...Cylinder, 39...Electronically controlled throttle valve, 40...Spark plug, 41...Spark gap, 48...High tension cord, 50...Ignition device, 52...Primary coil, 53...Secondary coil, 54...Igniter, 55...Diode, 56...Resistor, 57, 57a...Injector drive signal, 58...Throttle valve drive signal, 59...Ignition signal, 60...Intake VVT ​​drive signal, 61...Exhaust VVT drive signal

Claims

1. An ignition coil that generates a high voltage in a secondary coil by interrupting a current flowing in a primary coil; an igniter that turns on and off a current flowing through the primary coil; a spark plug connected to the secondary coil to generate a spark discharge and having an electrode disposed within the combustion chamber; A control device that transmits an ignition signal to the igniter, The control device includes: an ignition signal for a main discharge to ignite the hydrogen mixture in the combustion chamber; a secondary discharge ignition signal for reducing the voltage of the secondary coil during the intake stroke compared to the voltage of the secondary coil at the end of the main discharge, A control device for a spark ignition hydrogen engine.

2. The voltage of the secondary coil during the intake stroke is set to 1 kV or less.

2. The control device for a spark ignition hydrogen engine according to claim 1.

3. The timing at which the ignition signal for the secondary discharge switches from on to off is set within a range from 60° crank angle after the compression top dead center to the exhaust valve opening timing + 10° crank angle. The control device for a spark ignition type hydrogen engine according to claim 2.

4. The ON period of the ignition signal of the secondary discharge is set to 5% or more of the ON period of the ignition signal of the main discharge. The control device for a spark ignition type hydrogen engine according to claim 2.

5. The ON period of the ignition signal of the secondary discharge is set to 40% or less of the ON period of the ignition signal of the main discharge. The control device for a spark ignition type hydrogen engine according to claim 4.

6. Based on an engine state or an environmental state, switching is performed between sending and avoiding the ignition signal of the secondary discharge to the igniter. The control device for a spark ignition type hydrogen engine according to claim 2.

7. Switching between sending and avoiding the secondary discharge ignition signal to the igniter based on engine load information The control device for a spark ignition type hydrogen engine according to claim 6.

8. Switching between sending and avoiding the secondary discharge ignition signal to the igniter based on at least one of the engine load factor, throttle opening, torque, engine speed, intake pressure, cylinder pressure, intake air volume, exhaust gas flow rate, fuel flow rate, accelerator opening, load output, exhaust temperature, cooling water volume, water temperature, and oil temperature. The control device for a spark ignition type hydrogen engine according to claim 6.

9. sending an ignition signal for the secondary discharge to the igniter when at least one of the engine load factor, throttle opening, torque, engine speed, intake pressure, in-cylinder pressure, intake air volume, exhaust gas flow rate, fuel flow rate, accelerator opening, load output, exhaust temperature, cooling water volume, water temperature, or oil temperature is smaller than a predetermined value; When at least one of the engine load factor, throttle opening, torque, engine speed, intake pressure, cylinder pressure, intake air volume, exhaust gas flow rate, fuel flow rate, accelerator opening, load output, exhaust temperature, cooling water volume, water temperature, and oil temperature is not smaller than a predetermined value, the secondary discharge ignition signal is avoided from being sent to the igniter. The control device for a spark ignition type hydrogen engine according to claim 8.

10. The secondary discharge ignition signal is switched between being sent to the igniter and being avoided based on the hydrogen ratio of the fuel. The control device for a spark ignition type hydrogen engine according to claim 6.

11. When the hydrogen ratio of the fuel is greater than a predetermined value, an ignition signal for the secondary discharge is sent to the igniter, and when the hydrogen ratio of the fuel is not greater than the predetermined value, the ignition signal for the secondary discharge is not sent to the igniter. The control device for a spark ignition hydrogen engine according to claim 10.

12. In a case where the ignition signal of the secondary discharge is sent to the igniter, the ON period of the ignition signal of the main discharge is made shorter than in a case where the ignition signal of the secondary discharge is avoided from being sent to the igniter. The control device for a spark ignition type hydrogen engine according to claim 6.

13. An ignition coil that generates a high voltage in a secondary coil by interrupting a current flowing in a primary coil; an igniter that turns on and off a current flowing through the primary coil; a spark plug connected to the secondary coil to generate a spark discharge and having an electrode disposed within the combustion chamber; A method for controlling a spark ignition type hydrogen engine comprising: an ignition signal for a main discharge to ignite the hydrogen mixture in the combustion chamber; an ignition signal for a secondary discharge for reducing the voltage of the secondary coil during an intake stroke compared to the voltage of the secondary coil at the end of the main discharge; to the igniter. A method for controlling a spark ignition hydrogen engine.

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