JP2019190362A - Ignitor - Google Patents

Abstract

To provide an ignitor which can properly combust fuel in an internal combustion engine.SOLUTION: An ignitor 10 comprises: a cover 210 in which a sub-chamber 220 is formed, and also injection holes 211 for injecting flames generated in the sub-chamber 220 to a combustion chamber 38 of an internal combustion engine 30 are formed; an ignition plug 240 for igniting fuel in the sub-chamber 220; and a control part 100 for controlling an operation of the ignition plug 240. The control part 100 makes the ignition plug 240 perform ignition a plurality of times during one cycle composed of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke of the internal combustion engine 30.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an ignition device for an internal combustion engine.

  Various studies for optimizing the fuel injection amount and the ignition timing in the combustion chamber have been made for the purpose of suppressing harmful substances discharged from the internal combustion engine. When the internal combustion engine is cold-started, the amount of harmful substances discharged tends to increase, so that it is particularly necessary to optimize the injection amount as described above.

  In Patent Document 1 below, it is proposed to perform fuel injection divided into a plurality of times during one cycle including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke of the internal combustion engine. In the control method described in the document, ignition by the spark plug is performed only once immediately after the main injection. The post injection following the main injection is performed while combustion after the main injection occurs. For this reason, combustion can be continued even after post-injection without performing ignition again by the spark plug.

JP 2017-145776

  However, at the time of the second fuel injection, the oxygen concentration in the combustion chamber is reduced by the previous combustion, so that the injected fuel may not be properly ignited. Even if the ignition plug is ignited again after the post-injection, there is a high possibility that it will take a long time for the flame to spread throughout the combustion chamber or that the ignition will fail. As a countermeasure for this, it is conceivable to increase the fuel injection amount so that the fuel reaches the entire combustion chamber, but in this case, ignition is performed in a state where some of the fuel is not sufficiently vaporized. There is a concern that

  As described above, further improvements have been demanded for the configuration and control method for appropriately burning the injected fuel.

  An object of the present disclosure is to provide an ignition device capable of appropriately burning fuel in an internal combustion engine.

  The ignition device according to the present disclosure is an ignition device (10) of an internal combustion engine (30), and a sub chamber (220) is formed therein, and a flame generated in the sub chamber is transferred to a combustion chamber ( 38) a cover (210) further formed with an injection hole (211), an ignition plug (240) for igniting fuel in the sub chamber, and a control unit (100) for controlling the operation of the ignition plug And comprising. The control unit is configured to cause ignition by a spark plug a plurality of times during one cycle including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke of the internal combustion engine.

  In the ignition device having such a configuration, ignition of the fuel by the ignition plug is performed in the sub chamber, and the flame generated in the sub chamber is injected into the combustion chamber from the injection hole, thereby igniting the fuel in the combustion chamber. Done. Since the ignition of the fuel is performed a plurality of times during one cycle, the temperature of the exhaust gas becomes high, and the emission discharged together with the exhaust gas is reduced.

  Since the sub chamber is a narrow space as compared with the combustion chamber, the internal pressure is likely to increase during combustion. For this reason, even if there is little fuel which exists in a subchamber, a flame can be injected vigorously toward a combustion chamber from a subchamber. As a result, since the flame can reach a place relatively far from the nozzle hole in the combustion chamber, it is possible to appropriately burn the fuel in the entire combustion chamber.

  According to the present disclosure, an ignition device capable of appropriately burning fuel in an internal combustion engine is provided.

FIG. 1 is a diagram schematically showing a configuration of an ignition device according to the present embodiment and an internal combustion engine provided with the ignition device. FIG. 2 is a cross-sectional view showing the structure of the ignition device shown in FIG. FIG. 3 is a view showing a cross section taken along the line III-III in FIG. FIG. 4 is a diagram for explaining a control method of the ignition device according to the present embodiment. FIG. 5 is a flowchart showing a flow of processing executed by the control unit of the ignition device according to the present embodiment.

  Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  The ignition device 10 according to this embodiment is a device for igniting fuel (specifically, a mixture of fuel and air) in a combustion chamber 38 of the internal combustion engine 30 to cause combustion. Prior to the description of the ignition device 10, the configuration of the internal combustion engine 30 will be described first with reference to FIG.

  The internal combustion engine 30 is configured as a so-called four-cycle reciprocating engine. As shown in FIG. 1, an intake pipe 31 and an exhaust pipe 32 are connected to the internal combustion engine 30. The internal combustion engine 30 includes an intake valve 33, an exhaust valve 34, a piston 35, and an injector 40.

  The intake pipe 31 is a pipe for supplying combustion air to a combustion chamber 38 formed inside the internal combustion engine 30. The flow rate of air supplied from the intake pipe 31 to the combustion chamber 38 is adjusted by a throttle valve (not shown) arranged in the middle of the intake pipe 31.

  The exhaust pipe 32 is a pipe for discharging exhaust gas generated by combustion in the combustion chamber 38 from the combustion chamber 38 to the outside. A purification device (not shown) for purifying the exhaust gas with a catalyst is provided in the middle of the exhaust pipe 32.

  The intake valve 33 is a valve disposed at a connection portion between the intake pipe 31 and the internal combustion engine 30. When the intake valve 33 is opened, the supply of air to the combustion chamber 38 is started. Further, when the intake valve 33 is closed, the supply of air to the combustion chamber 38 is stopped.

  The exhaust valve 34 is a valve disposed at a connection portion between the exhaust pipe 32 and the internal combustion engine 30. When the exhaust valve 34 is opened, exhaust gas discharge from the combustion chamber 38 toward the exhaust pipe 32 is started. Further, when the exhaust valve 34 is closed, exhaust gas discharge from the combustion chamber 38 toward the exhaust pipe 32 is stopped.

  The piston 35 is a member that moves up and down inside the internal combustion engine 30. The already-described combustion chamber 38 is a portion above the piston 35 in the space formed inside the internal combustion engine 30. A connecting rod 36 and a crankshaft 37 are disposed below the piston 35. The vertical movement of the piston 35 is converted into a rotational movement of the crankshaft 37 by the connecting rod 36 and is taken out as a driving force of the vehicle.

  As is well known, when the internal combustion engine 30 operates, a cycle including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke is repeated. The intake stroke is a stroke in which air from the intake pipe 31 is taken into the combustion chamber 38 by the descending piston 35. The compression stroke is a stroke in which the air in the combustion chamber 38 is compressed by the rising piston 35. The expansion stroke is a stroke in which the piston 35 is pushed down by burning the fuel in the combustion chamber 38 and increasing its volume. The exhaust stroke is a stroke in which exhaust gas generated by combustion is discharged to the exhaust pipe 32 by the rising piston 35.

  The injector 40 is an on-off valve for injecting fuel into the combustion chamber 38. When the injector 40 is opened, fuel is injected from the tip of the injector 40 into the combustion chamber 38. Fuel injection is performed during the compression stroke. The opening / closing operation of the injector 40 is controlled by the control unit 100 described later. Thereby, the fuel injection timing and the injection amount from the injector 40 are adjusted as appropriate. The injector 40 corresponds to the “external injection valve” in the present embodiment.

  The configuration of the ignition device 10 will be described with reference to FIGS. The ignition device 10 includes an ignition unit 200 and a control unit 100.

  The ignition unit 200 is for igniting the fuel in the combustion chamber 38, and is attached to the upper end of the internal combustion engine 30 as shown in FIG. As shown in FIG. 2, the ignition unit 200 includes a cover 210, an injector 230, and a spark plug 240.

  The cover 210 is a generally cylindrical container whose lower end is closed. The cover 210 is disposed so as to penetrate the header 301 of the internal combustion engine 30 from the upper side in a state where the longitudinal direction thereof is along the vertical direction. A lower end portion of the cover 210 is disposed inside the combustion chamber 38.

  A sub chamber 220 which is a space is formed inside the cover 210. In the vicinity of the lower end of the cover 210, four nozzle holes 211 are formed in the portion disposed in the combustion chamber 38 as shown in FIGS. These nozzle holes 211 and the cover 210 are formed so as to be arranged at equal intervals along the circumferential direction. Each nozzle hole 211 communicates between the sub chamber 220 and the combustion chamber 38. The nozzle hole 211 is an opening for injecting the flame generated in the sub chamber 220 into the combustion chamber 38 and thereby igniting the fuel in the combustion chamber 38.

  The injector 230 is an on-off valve for injecting fuel into the sub chamber 220, and the entirety thereof is accommodated in the cover 210 (that is, the sub chamber 220). When the injector 230 is in an open state, fuel is injected from the tip 231 of the injector 230 into the sub chamber 220. The opening / closing operation of the injector 230 is controlled by the control unit 100. Thereby, the fuel injection timing and the injection amount from the injector 230 are appropriately adjusted. The injector 40 corresponds to the “internal injection valve” in the present embodiment.

  The spark plug 240 is a device for generating a spark discharge between the ground electrode 241 and the center electrode 242 and thereby igniting the fuel in the sub chamber 220. The entire spark plug 240 is accommodated inside the cover 210 (that is, the sub chamber 220).

  The “fuel in the sub chamber 220” ignited by the spark plug 240 may or may not be the fuel injected by the injector 230 described above. For example, when fuel is injected from the injector 40 into the combustion chamber 38 in the compression stroke, a part of the fuel in the combustion chamber 38 flows into the sub chamber 220 through the nozzle hole 211 with further compression thereafter.

  When the amount of fuel in the sub chamber 220 is sufficient as the amount of fuel passing through the nozzle hole 211, it is not necessary to inject fuel from the injector 230. If only the amount of fuel passing through the nozzle hole 211 is always sufficient, the sub-chamber 220 may not be provided with the injector 230.

  As described above, the fuel in the sub chamber 220 ignited by the spark plug 240 may include the fuel injected from the injector 230 (internal injection valve) or the fuel injected from the injector 40 (external injection valve). In some cases, fuel that subsequently flows into the sub chamber 220 through the nozzle hole 211 may be included.

  The operation of the spark plug 240 is controlled by the control unit 100. Thereby, the timing at which combustion starts to occur in the sub chamber 220, that is, the timing at which the flame is injected from the nozzle hole 211 is appropriately adjusted.

  Returning to FIG. 1, the description will be continued. The control unit 100 is a device for comprehensively controlling the overall operation of the ignition device 10. The control unit 100 is configured as a computer system having a CPU, a ROM, a RAM, and the like. As already described, the control unit 100 is configured to control the operation of the injector 40 provided in the internal combustion engine in addition to controlling the operation of the injector 230 and the spark plug 240.

  The control unit 100 may be configured as a dedicated device for controlling the operation of the injector 230 or the like, but other control devices (ECUs) in which some or all of the functions are mounted on the vehicle. It is good also as an aspect implement | achieved by. Moreover, it is good also as an aspect that a part or all function of the control part 100 is implement | achieved by the server installed, for example on the cloud.

  An overview of the control performed by the control unit 100 will be described with reference to FIG. FIG. 4A shows a time change of a signal output from the control unit 100 in order to inject fuel from the injector 230. Hereinafter, this signal is also referred to as “injection signal”. When the injection signal is ON, the injector 230 is in an open state, and when the injection signal is OFF, the injector 230 is in a closed state.

  FIG. 4B shows a time change of a signal output from the control unit 100 in order to cause spark discharge by the spark plug 240. Hereinafter, this signal is also referred to as “ignition signal”. When the ignition signal is switched from OFF to ON, spark discharge is performed by the spark plug 240.

  FIG. 4C shows the time change of the air-fuel ratio in the sub chamber 220, that is, the air-fuel ratio (A / F) of the air-fuel mixture. “TAF” shown in FIG. 4C is a so-called theoretical air-fuel ratio. When the graph of FIG. 4C is larger than TAF, the air-fuel ratio in the sub chamber 220 is leaner than the stoichiometric air-fuel ratio.

  FIG. 4D shows the change over time in the oxygen concentration in the sub chamber 220. FIG. 4E shows the time change of the pressure in the sub chamber 220.

  The horizontal axis of each graph in FIG. 4 shows a part of the period during which the compression stroke is switched to the expansion stroke in one cycle (intake stroke, compression stroke, expansion stroke, exhaust stroke) in the operation of the internal combustion engine 30. Has been. The time t30 shown in FIG. 4 is a time when the piston 35 reaches a so-called “top dead center”, and is a time when the compression stroke is switched to the expansion stroke. Note that the time when the piston 35 reaches top dead center and the time when the piston 35 switches from the compression stroke to the expansion stroke may or may not coincide with each other as described above.

  Fuel is injected into the combustion chamber 38 from the injector 40 in the middle of the compression stroke (before the period shown on the horizontal axis in FIG. 4). In the compression stroke, the fuel from the combustion chamber 38 flows into the sub chamber 220 through the nozzle hole 211. Therefore, as shown in FIG. 4C, the air-fuel ratio in the sub chamber 220 is leaner than the stoichiometric air-fuel ratio. As the combustion chamber 38 is compressed, the oxygen concentration in the sub chamber 220 gradually increases (FIG. 4D), and the pressure in the sub chamber 220 gradually increases (FIG. 4E).

  At time t10 prior to time t30, the injection signal is ON (FIG. 4A). Accordingly, since fuel is injected from the injector 230 into the sub chamber 220, the air-fuel ratio in the sub chamber 220 decreases after time t10 (FIG. 4C).

  At time t20 after time t10 and before time t30, the ignition signal is turned on (FIG. 4B). As a result, the fuel starts to burn in the sub chamber 220, so that after the time t20, the air-fuel ratio in the sub chamber 220 is rapidly increased (FIG. 4C), and the oxygen concentration in the sub chamber 220 is rapidly decreased. is doing. (FIG. 4D). Further, with the combustion of the fuel in the sub chamber 220, the pressure increase in the sub chamber 220 is further promoted (FIG. 4E).

  At this time, the flame generated by the combustion in the sub chamber 220 is injected from each nozzle hole 211 into the combustion chamber 38. Since the volume of the sub chamber 220 is relatively small, the internal pressure tends to increase during combustion. For this reason, flames are ejected vigorously from each nozzle hole 211, and the flames reach each part of the combustion chamber 38.

  In FIG. 1, the reference symbol BE is attached to a portion of the combustion chamber 38 farthest from the ignition unit 200. Hereinafter, this portion is also referred to as “bore end BE”. When the ignition unit 200 is a simple spark plug, it takes some time for the flame that has started to occur at the spark plug to reach the bore end BE due to the spread of combustion.

  However, in the present embodiment, the flame is ejected vigorously from the nozzle hole 211 and the flame reaches far, so the time until the flame reaches the bore end BE is relatively short. For this reason, it is prevented that the fuel remains unburned in a part of the combustion chamber 38 or the temperature of the exhaust gas is lowered, so that emission of emissions to the outside is suppressed. As described above, the ignition device 10 according to the present embodiment is configured to inject the flame generated in the sub chamber 220 into the combustion chamber 38 from the injection hole 211, so that the fuel is appropriately combusted in the entire combustion chamber 38. It is possible to make it.

  However, in this embodiment, after the first ignition at time t20, the second ignition is performed in the expansion stroke before all the fuel in the combustion chamber 38 is combusted. By causing combustion in the combustion chamber 38 again in the expansion stroke, the temperature of the exhaust gas rises, thereby further reducing emissions. Further, since the catalyst of the purification device is heated by the high-temperature exhaust gas, the catalyst is activated, and the effect of efficiently purifying the exhaust gas can be obtained.

  In order to realize the second ignition as described above, the injection signal is turned ON again at time t40 after time t30 (FIG. 4A). Accordingly, since fuel is injected from the injector 230 into the sub chamber 220, the air-fuel ratio in the sub chamber 220 decreases after time t40.

  At time t50 after time t40, the ignition signal is turned on again (FIG. 4B). As a result, the fuel starts to burn in the sub chamber 220, so that the air-fuel ratio in the sub chamber 220 suddenly increases after time t50 (FIG. 4C), and the oxygen concentration in the sub chamber 220 rapidly decreases. is doing. (FIG. 4D). Since the combustion of fuel in the sub chamber 220 is performed in two steps, two peaks appear in the pressure graph shown in FIG.

  As described above, the control unit 100 of the ignition device 10 according to the present embodiment performs ignition by the spark plug 240 during one cycle including the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke of the internal combustion engine 30. It is configured to be performed once. Thereby, since the ignition of the fuel in the combustion chamber 38 is performed twice, the temperature of the exhaust gas discharged from the internal combustion engine 30 can be raised, and as a result, the emission discharged to the outside can be reduced. The ignition plug 240 may be ignited twice during one cycle only when the internal combustion engine 30 or the purification device needs to be warmed up, for example, during cold start.

  According to the igniter 10 according to this embodiment, the amount of hydrocarbons discharged to the outside is reduced by 55% compared to the conventional amount, and the amount of fine particles is reduced by 65% compared to the conventional example. Confirmed by an experiment conducted by the authors.

  The ignition by the spark plug 240 may be performed twice as in the present embodiment, or may be performed three or more times. However, in any case, it is preferable that the control unit 100 controls the operation of the spark plug 240 so that the last ignition in one cycle is performed in the expansion stroke. When ignition is performed in the expansion stroke, the combustion energy generated by the ignition is hardly extracted as torque and converted into heat, so that the temperature of the exhaust gas can be increased efficiently. Thereby, the emitted emissions can be further reduced.

  As described above, when sufficient fuel is present in the sub chamber 220 when ignition is performed by the spark plug 240, fuel injection by the injector 230 may not be performed. For example, the injection signal may not be turned on at the time t10 of the compression stroke, and may be turned on only at the time t40 of the expansion stroke.

  The fuel injection by the injector 40, that is, the fuel supply to the combustion chamber 38 may be performed only once in the compression stroke, or may be performed twice or more in the period from the compression stroke to the expansion stroke. Good. If the fuel injection by the injector 40 is performed in a plurality of times, the amount of each injection becomes small and the combustion in the combustion chamber 38 becomes a so-called “lean burn”, so that the emitted emissions are further reduced. be able to. Further, in this case, the combustion period becomes longer, but the combustion in the combustion chamber 38 can be reliably continued by performing the ignition by the spark plug 240 a plurality of times.

  The timing at which a plurality of times of fuel injection by the injector 40 or the injector 230 and a plurality of times of ignition by the spark plug 240 are performed may be only the compression stroke or only the expansion stroke. Further, fuel injection or ignition may be performed over both the compression stroke and the expansion stroke.

  If the fuel injection by the injector 40 or the injector 230 is performed a plurality of times, the operation frequency of the injector becomes high, so that an effect of preventing clogging due to deposit (deposit) adhering to the tip of the injector is also obtained. .

  As shown in FIG. 4C, at the time t20 when the second ignition from the last in the cycle (first ignition in the present embodiment) is performed, the air-fuel ratio in the sub chamber 220 is leaner than the stoichiometric air-fuel ratio. It has become. The control unit 100 adjusts the operations of the injector 40 and the injector 230 so that ignition is performed when the air-fuel ratio in the sub chamber 220 is leaner than the stoichiometric air-fuel ratio, and the fuel is injected from these. The amount of fuel is adjusted.

  Even in the case where ignition by the spark plug 240 is performed three times or more, the air-fuel ratio at the time of ignition in the sub chamber 220 is higher than the stoichiometric air-fuel ratio until the second ignition from the last in one cycle is performed. Also, the fuel injection amount is adjusted so as to be lean. This is to ensure sufficient oxygen for combustion at the next ignition. In the period from the last to the second ignition in one cycle, the air-fuel ratio in the sub chamber 220 does not always need to be maintained leaner than the stoichiometric air-fuel ratio. It is sufficient that the air-fuel ratio is leaner than the stoichiometric air-fuel ratio.

  When the fuel injection from the injector 230 is not performed, the control unit 100 adjusts the air-fuel ratio as described above by controlling only the injector 40. For example, when the amount of fuel flowing into the sub chamber 220 from the nozzle hole 211 is small enough to be ignored, the control unit 100 adjusts the air-fuel ratio as described above by controlling only the injector 230. It is good.

  As shown in FIG. 4C, at the time t50 when the final ignition in one cycle is performed, the air-fuel ratio in the sub chamber 220 is the stoichiometric air-fuel ratio. Further, as shown in FIG. 4D, after the final ignition is performed, the oxygen concentration in the sub chamber 220 is substantially zero. Instead of such a mode, the control unit 100 operates the injector 40 and the injector 230 so that the air-fuel ratio in the sub chamber 220 when the final ignition in one cycle is performed becomes richer than the stoichiometric air-fuel ratio. It is good also as controlling.

  The contents of the processing performed by the control unit 100 in order to realize the above control will be described with reference to FIG. The series of processing shown in FIG. 5 is executed by the control unit 100 when the ignition unit ignites the combustion chamber 38.

  In the first step S01, it is determined whether or not the ignition to be performed is the last ignition in one cycle. If it is not the last ignition, the process proceeds to step S02. In step S02, the injection amounts of the injector 40 and the injector 230 are calculated so that the air-fuel ratio in the sub chamber 220 becomes leaner than the stoichiometric air-fuel ratio.

  In step S01, when the ignition to be performed is the last ignition, the process proceeds to step S05. In step S05, the respective injection amounts of the injector 40 and the injector 230 are calculated such that the air-fuel ratio in the sub chamber 220 substantially matches the stoichiometric air-fuel ratio.

  In step S03 following step S02 or step S05, a process of injecting fuel from the injector 40 and the injector 230 is performed. The timing at which the fuel is injected from each injector is not the same timing as each other, but is a preset timing for each. Further, the fuel injection amount from each injector is adjusted so as to coincide with the injection amount calculated in advance in step S02 or step S05.

  In step S04 following step S03, ignition by the spark plug 240 is performed. Thereby, the combustion of the fuel in the sub chamber 220 is started, and the injection of the flame from the nozzle hole 211 is started.

  By performing the processing as described above, the air-fuel ratio of the sub chamber 220 immediately before ignition by the spark plug 240 is appropriately adjusted. As a result, a plurality of times of ignition by the ignition device 10 and combustion in the combustion chamber 38 are always performed appropriately.

  In the above example, in step S05, the injection amount is calculated so that the air-fuel ratio in the sub chamber 220 matches the stoichiometric air-fuel ratio. However, the injection amount calculation method is not limited to this, and the injection amount may be calculated so as to be in a lean region or a rich region.

  In the embodiment described above, as described with reference to FIG. 2, the cover 210 is configured as a separate component from the internal combustion engine 30, and is attached to the header 301 of the internal combustion engine 30. Instead of such an aspect, the cover 210 may be formed by a part of the members constituting the internal combustion engine 30 (for example, the header 301). That is, the cover 210 may be configured so as to be integrated with a part of the internal combustion engine 30.

  The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those in which those skilled in the art appropriately modify the design of these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the specific examples described above and their arrangement, conditions, shape, and the like are not limited to those illustrated, and can be changed as appropriate. Each element included in each of the specific examples described above can be appropriately combined as long as no technical contradiction occurs.

10: ignition device 30: internal combustion engine 38: combustion chamber 100: control unit 210: cover 211: injection hole 220: sub chamber 240: ignition plug

Claims (5)

An ignition device (10) for an internal combustion engine (30),
A cover (210) in which a sub chamber (220) is formed and a nozzle hole (211) for injecting a flame generated in the sub chamber into the combustion chamber (38) of the internal combustion engine is further formed. When,
A spark plug (240) for igniting fuel in the sub chamber;
A control unit (100) for controlling the operation of the spark plug,
The ignition device is configured to cause ignition by the spark plug a plurality of times during one cycle including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke of the internal combustion engine. The internal combustion engine is provided with an external injection valve (40) for injecting fuel into the combustion chamber,
The fuel in the sub chamber ignited by the spark plug includes fuel that has been injected from the external injection valve and then flowed into the sub chamber through the nozzle hole.
The controller is
It is configured to control the operation of the external injection valve,
The operation of the external injection valve is controlled so that the air-fuel ratio at the time of ignition in the sub chamber is leaner than the stoichiometric air-fuel ratio until the second ignition from the last in the one cycle is performed. Ignition device according to. An internal injection valve (230) for injecting fuel into the sub chamber;
The fuel in the sub chamber ignited by the spark plug includes fuel injected from the internal injection valve,
The controller is
It is configured to control the operation of the internal injection valve,
The operation of the internal injection valve is controlled so that the air-fuel ratio at the time of ignition in the sub chamber is leaner than the stoichiometric air-fuel ratio until the second ignition from the last in the one cycle is performed. Or the ignition device of 2. The controller is
The ignition device according to any one of claims 1 to 3, wherein the operation of the spark plug is controlled so that the last ignition in the one cycle is performed in the expansion stroke.   The ignition device according to any one of claims 1 to 4, wherein the cover is formed by a part of a member constituting the internal combustion engine.

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