Ignition device

Abstract

To provide an ignition device capable of suppressing the unintended electric discharge due to ON-time voltage.SOLUTION: By switching a switching element 30 from OFF to ON at an ON time as a time when a pressure in a cylinder 91 is on the rise, an ignition device 1 starts to electrify a primary coil 21. A control part 60 sets the ON time to be later as the power supply voltage of a battery 10 gets higher. Then, on the basis of the power supply voltage and the pressure in the cylinder 91 at the ON time, it selects the power supply voltage for which it is determined that the electric discharge due to the ON-time voltage is hardly caused in a spark plug 50. This suppresses unintended electric discharge due to the ON-time voltage.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, an ignition device used in an internal combustion engine of an automobile is known. The ignition device has a spark plug disposed in a cylinder of the internal combustion engine. When the internal combustion engine is driven, the piston compresses the fuel gas in the cylinder, and the ignition device generates a spark discharge in the spark plug. Thereby, the fuel in the cylinder burns.

[0003] A conventional ignition device is described in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The ignition device includes a primary coil and a secondary coil that are electromagnetically coupled. After energizing the primary coil, the ignition device induces a high voltage in the secondary coil by interrupting the energization of the primary coil. Thereby, a discharge can be generated in the spark plug connected to the secondary coil.

[0006] In this type of ignition device, a voltage (ON voltage) is generated in the secondary coil when the primary coil is energized. This ON voltage can be a factor causing an unintentional discharge in the spark plug. In particular, in recent years, in order to reduce the emission of greenhouse gases, a fuel containing hydrogen may be used in an internal combustion engine. In that case, since hydrogen is more easily ignited than gasoline, there is a possibility that the fuel may be ignited by an unintentional discharge due to the ON voltage.

[0007] This invention has been made in view of these circumstances, and aims to provide an ignition device that can suppress unintended discharge due to the ON voltage. [Means for solving the problem]

[0008] To solve the above problems, the first invention of this application is: Uses hydrogen-containing fuel An ignition system for generating a spark discharge in the cylinder of an internal combustion engine, comprising: a battery; a primary coil connected to the battery; a switching element for switching the supply of power from the battery to the primary coil ON / OFF; a secondary coil electromagnetically coupled to the primary coil; a spark plug connected to the secondary coil; and a control unit for controlling the battery and the switching element, wherein the battery is capable of selecting multiple power supply voltages; and the control unit starts supplying power to the primary coil by switching the switching element from OFF to ON at the ON time, which is the time when the pressure in the cylinder is rising; and the higher the power supply voltage of the battery, the later the ON time is set. The ratio of the pressure inside the cylinder to the power supply voltage (pressure / power supply voltage) at the aforementioned ON time is set to be greater than a preset threshold. Select the power supply voltage.

[0009] The second invention of this application is an ignition device of the first invention, wherein the control unit controls the rotational speed of the internal combustion engine and the power supply voltage and A power-on time map that defines the relationship between combinations and the power-on time to be set. Based on this, the energizing time to the primary coil is set, and the rotational speed of the internal combustion engine and the pressure inside the cylinder are used. An ignition time map that defines the relationship between the combination of and the OFF time to be set. Based on this, an OFF time is set to interrupt the power supply to the primary coil, and the ON time is set based on the power supply time and the OFF time.

[0011] This application 3 The invention is the first invention. or the second invention The ignition device wherein, if the load of the internal combustion engine is lower than a preset threshold, the control unit delays the ON time after determining the power supply voltage. [Effects of the Invention]

[0013] The first invention of this application to the first invention3 According to the invention, the control unit The ratio of the pressure inside the cylinder to the power supply voltage (pressure / power supply voltage) at the ON time should be greater than a preset threshold. selects the power supply voltage. Thereby, unintentional discharge due to the ON voltage can be suppressed.

[0014] In particular, according to the 3 invention, since the pressure in the cylinder at the ON time becomes higher, the discharge due to the ON voltage can be more suppressed.

[0015] Furthermore, the first to third inventions of this application According to, since a fuel containing hydrogen is used, the emission amount of greenhouse gases can be reduced. However, although hydrogen has a problem of being easy to ignite, according to the present invention, the ignition of hydrogen due to the ON voltage can be suppressed.

Brief Description of the Drawings

[0016] [Figure 1] It is a diagram showing the configuration of the ignition device. [Figure 2] It is a flowchart showing the flow of operations of the ignition device and the internal combustion engine. ]> [Figure 3] It is a graph showing the change in pressure in the cylinder. [Figure 4] It is a graph showing the change over time of the ON / OFF state of the switching element, the secondary current, and the secondary voltage. [Figure 5] It is a flowchart showing the flow of the process of selecting the power supply voltage. [Figure 6] It is an example of an energization time map. [Figure 7] It is an example of an ignition time map. [Figure 8] It is a graph showing the relationship between the power supply voltage of the battery and the pressure in the cylinder, and the likelihood of abnormal discharge. [Figure 9] It is a flowchart showing the flow of the process according to the modification.

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] <1. Configuration of Ignition Device> FIG. 1 is a diagram showing the configuration of an ignition device 1 according to an embodiment of the present invention. This ignition device 1 is mounted on an automobile and is a device for igniting the fuel supplied to the cylinder 91 of the internal combustion engine 9. In this embodiment, it is assumed that a fuel containing hydrogen is used in the internal combustion engine 9.

[0019] The internal combustion engine 9 includes a cylinder 91 which is a combustion chamber, and a piston 92 for compressing the fuel in the cylinder 91. An intake pipe 93 and an exhaust pipe 95 are connected to the cylinder 91. An intake valve 94 is provided at the connection portion between the intake pipe 93 and the cylinder 91. When the piston 92 descends with the intake valve 94 open, an air-fuel mixture containing fuel is supplied from the intake pipe 93 into the cylinder 91. An exhaust valve 96 is provided at the connection portion between the exhaust pipe 95 and the cylinder 91. When the piston 92 ascends with the exhaust valve 96 open, the gas in the cylinder 91 is discharged into the exhaust pipe 95. Further, when the piston 92 ascends with the intake valve 94 and the exhaust valve 96 closed, the air-fuel mixture in the cylinder 91 is compressed.

[0020] As shown in FIG. 1, the ignition device 1 includes a battery 10, an ignition coil 20, a switching element 30, a diode 40, an ignition plug 50, and a control unit 60.

[0021] The battery 10 is a power supply device capable of supplying DC power. The battery 10 can select a plurality of power supply voltages. The battery 10 outputs one power supply voltage selected by the control unit 60 from among the plurality of power supply voltages. As a method for switching the power supply voltage, for example, a method of changing the voltage by a regulator of an alternator, a method of switching and using storage batteries with different voltages, etc. can be considered.

[0022] The ignition coil 20 is a unit for inducing a high voltage to the spark plug 50. As shown in Figure 1, the ignition coil 20 has a primary coil 21, a secondary coil 22, and an iron core 23. The primary coil 21 and the secondary coil 22 are electromagnetically coupled via the iron core 23. The number of turns of the secondary coil 22 is greater than the number of turns of the primary coil 21.

[0023] One end of the primary coil 21 is electrically connected to the battery 10 via a power line 71. The other end of the primary coil 21 is grounded to the earth via a grounding wire 72. A switching element 30 is interposed in the grounding wire 72.

[0024] One end of the secondary coil 22 is electrically connected to a connection point 73 located on the path of the power line 71 via a first connecting wire 74. A diode 40 is interposed in the first connecting wire 74. The other end of the secondary coil 22 is electrically connected to the center electrode 51 of the spark plug 50, which will be described later, via a second connecting wire 75.

[0025] The switching element 30 is a switch that turns the power supply from the battery 10 to the primary coil 21 ON / OFF. For example, an IGBT (Insulated Gate Bipolar Transistor) is used for the switching element 30. The collector of the switching element 30 is electrically connected to the other end of the primary coil 21 as described above. The emitter of the switching element 30 is electrically connected to ground.

[0026] The diode 40 is provided on the first connecting wire 74 that connects one end of the secondary coil 22 to the connection part 73. The diode 40 is connected in series with the secondary coil 22 with the forward direction being from the secondary coil 22 to the connection part 73.

[0027] The spark plug 50 is located inside the cylinder of the internal combustion engine 9. The spark plug 50 has a center electrode 51 and a ground electrode 52. The center electrode 51 is electrically connected to the other end of the secondary coil 22 via a second connecting wire 75. The ground electrode 52 is grounded to the ground from the engine block via the cylinder 91.

[0028] The control unit 60 is a unit for controlling the discharge operation of the spark plug 50 by the ignition coil 20. The control unit 60 is composed of a microcontroller or computer having a CPU and memory. The control unit 60 is, for example, an ECU (Engine Control Unit) installed in an automobile. The control unit 60 is electrically connected to the battery 10 and the switching element 30. The control unit 60 switches the power supply voltage of the battery 10 by outputting a control signal to the battery 10. The control unit 60 also controls the ON / OFF state of the switching element 30 by outputting a control signal to the switching element 30.

[0029] <2. Operation of the ignition system> Next, the operation of the ignition device 1 described above will be explained. Figure 2 is a flowchart showing the operation flow of the ignition device 1 and the internal combustion engine 9. Figure 3 is a graph showing the change in pressure inside cylinder 91 when the operation shown in Figure 2 is performed. The horizontal axis of Figure 3 represents time. The vertical axis of Figure 3 represents the pressure inside cylinder 91.

[0030] Figure 4 is a graph showing the ON / OFF state of the switching element 30, the secondary current, and the change in secondary voltage over time when performing steps S2 to S5 in Figure 2. The secondary current is the current flowing through the secondary coil 22. The secondary voltage is the voltage at the other end of the secondary coil 22 (the side with the spark plug 50).

[0031] The ignition device 1 repeatedly performs steps S1 to S6 in Figure 2 in accordance with the operation of the internal combustion engine 9. If the internal combustion engine 9 is a four-stroke engine, the piston 92 makes two reciprocating movements within the cylinder 91 during the operation of steps S1 to S6 in Figure 2. Specifically, the piston 92 makes one reciprocating movement in steps S2 to S5 in Figure 2, and one reciprocating movement in steps S6 to S1.

[0032] First, the internal combustion engine 9 opens the intake valve 94, moving the piston 92 from top dead center to bottom dead center. This supplies a fuel-air mixture from the intake manifold 93 into the cylinder 91 (step S1). Next, at time t0, the piston 92 begins to move from bottom dead center to top dead center. The internal combustion engine 9 also closes the intake valve 94. This initiates compression of the fuel-air mixture (step S2).

[0033] The ignition device 1 starts energizing the primary coil 21 at time t1 (hereinafter referred to as "ON time") when the pressure in cylinder 91 is rising. Specifically, the control unit 60 switches the switching element 30 from OFF (open state) to ON (closed state) (step S3). As a result, primary current flows from the battery 10 to ground via the power line 71, primary coil 21, and ground line 72. This causes primary energy to be stored in the ignition coil 20.

[0034] Subsequently, at a time t2 (hereinafter referred to as "OFF time") prior to the time when the piston 92 reaches top dead center, the control unit 60 switches the switching element 30 from ON (closed state) to OFF (open state) (step S4). This interrupts the current supply to the primary coil 21. As a result, an induced electromotive force is induced in the secondary coil 22 via the iron core 23, and a high voltage corresponding to the primary energy is generated in the secondary coil 22. The positive or negative sign of the induced electromotive force depends on the winding direction of the secondary coil 22, but in this embodiment, a high voltage is generated in the secondary coil 22 with one end (diode 40 side) being positive and the other end (spark plug 50 side) being negative.

[0035] When a high voltage is generated in the secondary coil 22, a high voltage is also generated between the center electrode 51 and the ground electrode 52 of the spark plug 50. Specifically, the voltage value of the center electrode 51 becomes several thousand volts to tens of thousands of volts less than the voltage value of the ground electrode 52 (ground voltage). This high voltage causes dielectric breakdown between the center electrode 51 and the ground electrode 52 of the spark plug 50, resulting in a spark discharge between the two electrodes. This spark causes the fuel supplied to the cylinder 91 of the internal combustion engine 9 to burn (step S5).

[0036] In the graph of Figure 4, a discharge occurs at the spark plug 50 between time t2 and time t3. At this time, due to dielectric breakdown between the center electrode 51 and the ground electrode 52, a secondary current flows from the ground to the first connecting wire 74 through the ground electrode 52, the center electrode 51, the second connecting wire 75, and the secondary coil 22. This secondary current flows in the forward direction through the diode 40.

[0037] When the fuel in cylinder 91 burns, the pressure inside cylinder 91 increases, causing piston 92 to move from top dead center to bottom dead center. Then, the internal combustion engine 9 opens the exhaust valve 96. Also, piston 92 moves from bottom dead center to top dead center. As a result, the combustion gases in cylinder 91 are discharged into the exhaust pipe 95 (step S6).

[0038] <3. Regarding the voltage when ON> At the ON time t1 described above, when current is supplied to the primary coil 21, the primary coil 21 and the secondary coil 22 are electromagnetically coupled, and as shown in Figure 4, a voltage (hereinafter referred to as "ON voltage Vo") is generated in the secondary coil 22. In this embodiment, an ON voltage Vo is generated in the secondary coil 22, with one end (diode 40 side) being negative and the other end (spark plug 50 side) being positive.

[0039] This ON voltage Vo can cause unintended discharge (hereinafter referred to as "abnormal discharge") in the spark plug 50. In particular, when the internal combustion engine 9 uses a fuel containing hydrogen, the fuel ignites more easily than when using gasoline. For this reason, it is desirable to prevent abnormal discharge caused by the ON voltage Vo as much as possible.

[0040] Therefore, in this ignition device 1, a diode 40 is inserted in the first connecting wire 74 between the secondary coil 22 and the connection part 73. The diode 40 is connected in a direction such that the forward direction is from the secondary coil 22 to the connection part 73. In this way, the flow of current from the battery 10 to the secondary coil 22 is suppressed while the primary coil 21 is energized. This suppresses the occurrence of abnormal discharge due to the ON voltage Vo in the spark plug 50. However, even with the diode 40 inserted, some ON voltage will still be generated.

[0041] Furthermore, as described above, the battery 10 in this embodiment allows for the selection of multiple power supply voltages. This ignition device 1 has a function that further suppresses abnormal discharge due to the ON voltage Vo by appropriately selecting the power supply voltage of the battery 10 via the control unit 60. This function will be described below.

[0042] Figure 5 is a flowchart showing the process flow by which the control unit 60 selects the power supply voltage. As shown in Figure 5, the control unit 60 first grasps the operating state of the internal combustion engine 9 (step S11). Specifically, it detects or calculates the rotational speed of the internal combustion engine 9 and the pressure inside the cylinder 91 based on the measured values ​​of various sensors installed on the internal combustion engine 9.

[0043] Next, the control unit 60 sets the energizing time Δt to the primary coil 21 (the time from ON time t1 to OFF time t2) (step S12). The control unit 60's memory has an energizing time map M1 stored in advance. Figure 6 is an example of the energizing time map M1. As shown in Figure 6, the energizing time map M1 is table data that defines the energizing time Δt to be set for each combination of the rotational speed of the internal combustion engine 9 and the power supply voltage of the battery 10. In step S12, the control unit 60 determines the energizing time Δt corresponding to the rotational speed of the internal combustion engine 9 and the current power supply voltage of the battery 10 based on the energizing time map M1.

[0044] Furthermore, the control unit 60 sets an OFF time t2 to cut off the power supply to the primary coil 21 (step S13). The control unit 60's memory has an ignition time map M2 stored in advance. Figure 7 is an example of the ignition time map M2. As shown in Figure 7, the ignition time map M2 is table data that defines the OFF time t2 (advance ignition angle relative to top dead center) to be set for a combination of the rotational speed of the internal combustion engine 9 and the pressure in the cylinder 91. In step S13, the control unit 60 determines the OFF time t2 corresponding to the rotational speed of the internal combustion engine 9 and the pressure in the cylinder 91 based on the ignition time map M2.

[0045] Next, the control unit 60 sets the ON time t1 based on the energizing time Δt set in step S12 and the OFF time t2 set in step S13 (step S14). Specifically, the ON time t1 is calculated as the time that is energizing time Δt earlier than the OFF time t2.

[0046] Subsequently, the control unit 60 evaluates the possibility of abnormal discharge occurring at the spark plug 50 due to the ON voltage Vo, based on the power supply voltage of the battery 10 and the pressure in the cylinder 91 at the ON time t1 (step S15).

[0047] The ON voltage Vo is generated proportionally to the power supply voltage of the battery 10. Therefore, lowering the power supply voltage of the battery 10 can suppress the ON voltage Vo. Consequently, if the pressure inside the cylinder 91 is the same, lowering the power supply voltage of the battery 10 makes abnormal discharge due to the ON voltage Vo less likely to occur.

[0048] However, if the power supply voltage of the battery 10 is lowered, the energizing time Δt to the primary coil 21 is set to be longer in step S12 above in order to store the necessary primary energy. In that case, the ON time t1 is set earlier in step S14 above. As can be seen from the graph in Figure 3, when the ON time t1 is set earlier, the pressure inside the cylinder 91 at the ON time t1 becomes lower. This creates a situation in the cylinder 91 where abnormal discharge due to the ON voltage Vo is more likely to occur.

[0049] Figure 8 is a graph showing the relationship between the power supply voltage of the battery 10, the pressure inside the cylinder 91, and the likelihood of abnormal discharge occurring. The horizontal axis of Figure 8 represents the power supply voltage of the battery 10. The vertical axis of Figure 8 represents the pressure inside the cylinder 91 at ON time t1. As described above, the higher the power supply voltage of the battery 10, the more likely abnormal discharge due to the ON voltage Vo is to occur, and the lower the power supply voltage of the battery 10, the less likely abnormal discharge due to the ON voltage Vo is to occur. Also, as described above, the lower the pressure inside the cylinder 91 at ON time t1, the more likely abnormal discharge due to the ON voltage Vo is to occur, and the higher the pressure inside the cylinder 91 at ON time t1, the less likely abnormal discharge due to the ON voltage Vo is to occur.

[0050] The control unit 60 takes these circumstances into consideration and determines whether or not a situation is likely to occur due to the ON voltage Vo. For example, as shown in Figure 8, if the ratio of the pressure inside cylinder 91 to the power supply voltage of battery 10 (pressure / power supply voltage) is smaller than a preset threshold TH, it is determined that a situation is likely to occur, and if the ratio is larger than a preset threshold TH, it is determined that a situation is unlikely to occur. However, the control unit 60 may also determine whether or not a situation is likely to occur based on other criteria, using the power supply voltage of battery 10 and the pressure inside cylinder 91 at ON time t1.

[0051] If the evaluation in step S15 determines that abnormal discharge is unlikely to occur (step S16: No), the control unit 60 maintains the current power supply voltage of the battery 10 (step S17).

[0052] On the other hand, if the evaluation in step S15 determines that the situation is prone to abnormal discharge (step S16: Yes), the control unit 60 repeats the processes in steps S12 to S15 described above for both the case where the power supply voltage is increased and the case where it is decreased. This re-evaluates the possibility of abnormal discharge occurring for both the case where the power supply voltage is increased and the case where it is decreased (step S18). Then, the control unit 60 changes the power supply voltage of the battery 10 to the voltage value that is less prone to abnormal discharge among the cases where the power supply voltage is increased and the case where it is decreased (step S19).

[0053] As described above, in this ignition system 1, the battery 10 can select from multiple power supply voltages. The control unit 60 sets the ON time t1 later the higher the power supply voltage of the battery 10. Then, based on the power supply voltage and the pressure in the cylinder 91 at ON time t1, it selects a power supply voltage that is determined to be less likely to cause abnormal discharge at the spark plug 50.

[0054] When the power supply voltage is low, the ON voltage Vo is low, but the ON time t1 is set earlier, resulting in a lower pressure in cylinder 91 at ON time t1. On the other hand, when the power supply voltage is high, the ON voltage Vo is high, but the ON time t1 is set later, resulting in a higher pressure in cylinder 91 at ON time t1. The control unit 60 selects the case where discharge due to the ON voltage Vo is less likely to occur, between the low voltage and low pressure in cylinder 91 and the high voltage and high pressure in cylinder 91. This suppresses unintended discharge due to the ON voltage Vo.

[0055] In particular, the ignition device 1 of this embodiment ensures that the relationship between the power supply voltage of the battery 10 and the pressure inside the cylinder 91 at ON time t1 is within a preset tolerance range (for example, the ratio of the pressure inside the cylinder 91 to the power supply voltage of the battery 10 is greater than a preset threshold TH). Large The power supply voltage is selected accordingly. This allows for proper suppression of unintended discharge due to the ON voltage Vo.

[0056] <4. Variation> Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0057] <4-1. First variation> For example, the process in Figure 9 may be added after the process in Figure 5. In the example in Figure 9, after the power supply voltage is determined in step S17 or step S19 of Figure 5, the control unit 60 determines whether the load on the internal combustion engine 9 is lower than a preset threshold (step S20).

[0058] If the load of the internal combustion engine 9 is above the threshold (step S20: No), the control unit 60 maintains the ON time t1 set in step S14 of Figure 5 (step S21). On the other hand, if the load of the internal combustion engine 9 is less than the threshold (step S20: Yes), the control unit 60 uses a low-load energizing time map, different from the energizing time map M1 of the above embodiment, to repeat the processes of steps S12 to S14. This resets the ON time t1 (step S22).

[0059] The energizing time map for low loads has a shorter energizing time Δt than the energizing time map M1 in the above embodiment. Therefore, in step S22, the energizing time Δt is set shorter than during the processing in Figure 5. Consequently, the ON time t1 is set later than during the processing in Figure 5. By delaying the ON time t1 after determining the power supply voltage in this way, the pressure inside the cylinder 91 at the ON time t1 becomes higher. Therefore, abnormal discharge due to the ON voltage Vo can be further suppressed.

[0060] <4-2. Other variations> In the above embodiment, the case where the internal combustion engine 9 is a four-stroke engine was described. However, the internal combustion engine to which the ignition device of the present invention is applied is not necessarily limited to a four-stroke engine, but may also be a two-stroke engine or the like.

[0061] Furthermore, the above embodiment described an ignition device 1 mounted on an automobile. However, the "ignition device" of the present invention may be mounted on transportation equipment other than automobiles. Also, the "ignition device" of the present invention may be mounted on industrial machinery or generators other than transportation equipment.

[0062] Furthermore, the detailed configuration of the ignition device may be modified as appropriate without departing from the spirit of the present invention. In addition, the elements that appear in the above embodiments and modifications may be combined as appropriate without creating any inconsistencies. [Explanation of Symbols]

[0063] 1 Ignition device 9. Internal combustion engine 10 batteries 20 Ignition coil 21 Primary coil 22 Secondary coil 23 Iron core 30 Switching elements 40 diodes 50 Spark plugs 51 Center electrode 52 Ground electrode 60 Control Unit 71 Power line 72 Ground wire 73 Connection section 74. First connection line 75 Second connection line 91 cylinders 92 Pistons 93 Intake pipe 94 Intake valve 95 Exhaust pipe 96 Exhaust Valve M1 Power-on Time Map M2 Ignition Time Map TH threshold Vo voltage when ON t1 ON time t2 OFF time Δt: energization time

Claims

1. An ignition device for generating a spark discharge in the cylinder of an internal combustion engine using a hydrogen-containing fuel, Battery and The primary coil connected to the aforementioned battery, A switching element that switches the ON / OFF of the current flow from the battery to the primary coil, The primary coil and the secondary coil are electromagnetically coupled, The spark plug connected to the secondary coil, A control unit that controls the battery and the switching element, Equipped with, The aforementioned battery allows for the selection of multiple power supply voltages. The control unit, At the ON time, which is the time when the pressure inside the cylinder is rising, the switching element is switched from OFF to ON, thereby initiating the supply of power to the primary coil. The higher the power supply voltage of the aforementioned battery, the later the ON time should be set. An ignition device that selects a power supply voltage such that the ratio of the pressure inside the cylinder to the power supply voltage (pressure / power supply voltage) at the aforementioned ON time is greater than a preset threshold.

2. An ignition device according to claim 1, The control unit, Based on an energizing time map that defines the relationship between the rotational speed of the internal combustion engine, the power supply voltage, and the energizing time to be set, the energizing time to the primary coil is set. Based on an ignition time map that defines the relationship between the rotational speed of the internal combustion engine, the pressure inside the cylinder, and the OFF time to be set, the OFF time for cutting off power to the primary coil is set. An ignition device that sets the ON time based on the energizing time and the OFF time.

3. An ignition device according to claim 1 or claim 2, The control unit delays the ON time after determining the power supply voltage when the load of the internal combustion engine is lower than a preset threshold.

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