Internal combustion engine system

Abstract

To provide an internal combustion engine system capable of enhancing efficiency and stability of combustion at start of an internal combustion engine body by using a first ignition device disposed in a main combustion chamber and a second ignition device disposed in an auxiliary combustion chamber.SOLUTION: An internal combustion engine system includes: a body that has a main combustion chamber 40, an auxiliary combustion chamber 42, a first ignition plug 61 disposed in the main combustion chamber 40 and a second ignition plug 62 disposed in the auxiliary combustion chamber 42; and a control device that controls the body. The control device executes fuel increase processing for increasing a fuel supply amount to the main combustion chamber 40 compared to during non-cranking for a predetermined time including cranking by using a starter motor after start of the body, ignites an air-fuel mixture by using the second ignition plug 62 at the time of initial explosion of the body, and ignites the air-fuel mixture by using both of the first ignition plug 61 and the second ignition plug 62 during transition processing to an idling operation after complete explosion of the body.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine system having an ignition device disposed in a main combustion chamber and an ignition device disposed in a pre-combustion chamber. [Background technology]

[0002] Conventionally, there is known a technique relating to an internal combustion engine system equipped with an ignition device arranged in a main combustion chamber and an ignition device arranged in an auxiliary combustion chamber. For example, Patent Document 1 describes an internal combustion engine system in which, in a load region lower than a control switching line, an ignition plug (ignition device) in the main combustion chamber is ignited while intake is being taken in so as to easily form a tumble vortex in the main combustion chamber, and in a load region higher than the control switching line, an air-fuel mixture is taken into the main combustion chamber at a high flow rate so as to fill the auxiliary combustion chamber with a rich air-fuel mixture, while the ignition plug (ignition device) in the auxiliary combustion chamber is ignited. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-119297 Summary of the Invention [Problem to be solved by the invention]

[0004] The ignition control described in Patent Document 1 uses one of the ignition devices depending on the load on the internal combustion engine, but does not specifically describe ignition control when starting the internal combustion engine. However, during the start-up process of the internal combustion engine or immediately thereafter, the intake amount and fuel supply amount may not be stable, and it is necessary to perform appropriate ignition control according to the situation.

[0005] The present invention has been made in consideration of these problems, and its purpose is to provide an internal combustion engine system that can improve the efficiency and stability of combustion when starting the internal combustion engine body by using a first ignition device arranged in the main combustion chamber and a second ignition device arranged in the auxiliary combustion chamber. [Means for solving the problem]

[0006] In order to achieve the above object, the internal combustion engine system of the present invention comprises an internal combustion engine body including a main combustion chamber filled with a mixture of air and fuel, an auxiliary combustion chamber communicating with the main combustion chamber via a plurality of communication holes, a first ignition device arranged in the main combustion chamber and igniting the mixture in the main combustion chamber, and a second ignition device arranged in the auxiliary combustion chamber and igniting the mixture in the auxiliary combustion chamber, and a control device that controls the internal combustion engine body, wherein after the internal combustion engine body has begun to start, the control device executes a fuel increase process that increases the amount of fuel supplied compared to during non-cranking for a predetermined period of time including during cranking that uses an electric motor to increase the rotation speed of the internal combustion engine body, and ignites the mixture by the second ignition device at the first combustion of the internal combustion engine body, and after complete combustion of the internal combustion engine body, ignites the mixture by both the first ignition device and the second ignition device during the transition process to idling operation. [Effects of the Invention]

[0007] According to the internal combustion engine system of the present invention, by using a first ignition device arranged in the main combustion chamber and a second ignition device arranged in the auxiliary combustion chamber, it is possible to improve the efficiency and stability of combustion when starting the internal combustion engine body. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an internal combustion engine system according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram schematically showing a cylinder. [Figure 3]10 is an explanatory diagram showing an example of various control states and time-dependent changes in air-fuel ratio, fuel injection amount, charging efficiency, and rotation speed when cranking start of an internal combustion engine body is performed. FIG. [Figure 4] 10 is an explanatory diagram showing an example of various control states and time changes in air-fuel ratio, fuel injection amount, filling efficiency, and rotation speed when motoring start of an internal combustion engine body is performed. FIG. [Figure 5] FIG. 4 is an explanatory diagram schematically showing another example of the arrangement positions of the first spark plug and the second spark plug. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (Internal combustion engine) FIG. 1 is a schematic diagram of an internal combustion engine system according to an embodiment. The internal combustion engine system 1 is mounted on, for example, a vehicle. The internal combustion engine system 1 includes an internal combustion engine main body 10 (hereinafter referred to as "main body 10"), which is, for example, a gasoline engine, and a control device 50. An air cleaner 6, an intercooler 7, and a throttle valve 8 are provided in an intake passage 5 of the main body 10 along the flow of intake air, upstream of the intake port 2 of each cylinder 30. The intake passage 5 is also provided with an intake flow sensor 17 that detects the intake amount, and an intake pressure sensor 18 that detects the intake pressure of an intake manifold (not shown). Meanwhile, an exhaust passage 11 of the main body 10 is provided with an upstream exhaust purification catalyst 12 and a downstream exhaust purification catalyst 13 along the flow of exhaust from the exhaust port 3 of each cylinder 30. The exhaust passage 11 is also provided with a sensor 19 for detecting the air-fuel ratio of the main body 10. A so-called lambda sensor or an O2 sensor can be used as the sensor 19.

[0011] The main body 10 is also provided with a turbocharger 15 and an EGR system 16. The turbocharger 15 rotates a turbine (not shown) using exhaust gas flowing through the exhaust passage 11, and supplies compressed air to the intake side by rotating a compressor (not shown) connected to the turbine. The EGR system 16 includes an EGR passage 20 that connects the exhaust passage 11 and the intake passage 5, an EGR valve 21 that changes the flow area of ​​the EGR passage 20, and an EGR cooler 22 that cools the exhaust gas passing through the EGR passage 20.

[0012] 2 is an explanatory diagram that schematically shows a cylinder 30. The cylinder 30 is composed of a cylinder head 34, a cylinder block 36, and a piston 37 that is slidably disposed within the cylinder block 36 via a cylindrical cylinder liner (not shown). The cylinder head 34 is provided with an intake port 2 and an exhaust port 3 corresponding to each cylinder 30, and each intake port 2 is provided with an intake valve 32 that can be opened and closed, and each exhaust port 3 is provided with an exhaust valve 33 that can be opened and closed.

[0013] The cylinder 30 is provided with a main combustion chamber 40, which is a space surrounded by the cylinder head 34, cylinder block 36, and piston 37. In the main body 10 of this embodiment, an injector 9 serving as a fuel injection device is provided in the intake port 2, and an air-fuel mixture mixed with air in the intake port 2 is supplied into the main combustion chamber 40. Note that the main body 10 may also be provided with a direct injection injector that injects fuel directly into the main combustion chamber. The cylinder block 36 is provided with a first spark plug 61 (first ignition device) that ignites the air-fuel mixture in the main combustion chamber 40.

[0014] Furthermore, within the main combustion chamber 40, there is provided an auxiliary combustion chamber 42, which is a space separated by a partition wall 44 attached to the top of the main combustion chamber 40 (i.e., the cylinder head 34). A plurality of communication holes 46 are formed in the partition wall 44. As a result, the main combustion chamber 40 and the auxiliary combustion chamber 42 are in communication via the plurality of communication holes 46, and the air-fuel mixture within the main combustion chamber 40 flows into the auxiliary combustion chamber 42. A second spark plug 62 (second ignition device) is disposed within the auxiliary combustion chamber 42, which ignites the air-fuel mixture that flows in from the main combustion chamber 40.

[0015] When the first spark plug 61 ignites the air-fuel mixture in the main combustion chamber 40 (hereinafter referred to as "SI ignition"), the flame F1 propagates from the first spark plug 61 toward the exhaust port 3 due to the flow of the air-fuel mixture in the main combustion chamber 40, as shown by the dashed dotted line in the figure. In this way, stable ignition can be achieved by directly igniting the air-fuel mixture filled in the main combustion chamber 40. Furthermore, in this embodiment, the flame F1 caused by SI ignition is set to spread in the extension direction of the face of the piston 37. In this configuration, the flame F1 propagates a longer distance within the main combustion chamber 40 than when the flame F1 caused by SI ignition spreads from the center of the main combustion chamber 40. As a result, combustion can be slowed down.

[0016] On the other hand, when the second spark plug 62 ignites the air-fuel mixture in the auxiliary combustion chamber 42 (hereinafter referred to as "JET ignition"), as shown by the dashed line in the figure, flame F2 is injected from the auxiliary combustion chamber 42 into the main combustion chamber 40 through the multiple communication holes 46. As a result, flame F2 can be quickly propagated within the main combustion chamber 40, accelerating combustion and ultimately improving the thermal efficiency of the main body 10. Furthermore, when both SI ignition and JET ignition are performed, flame F2 from JET ignition can combust unburned fuel that could not be ignited by SI ignition.

[0017] The main body 10 configured as described above is controlled by a control device 50 (FIG. 1). The control device 50 is composed of an output device, storage devices (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), etc. The control device 50 acquires information such as the crank angle, intake air volume, exhaust gas temperature, and EGR gas volume from various sensors provided in the main body 10, and appropriately controls the throttle valve 8, EGR valve 21, turbocharger 15, the fuel injection volume from the injector 9, intake valve 32, exhaust valve 33, first spark plug 61, second spark plug 62, etc. based on the acquired information. For example, the control device 50 performs feedback control (hereinafter referred to as "F / B control") to adjust the intake air volume and fuel supply volume so that the air-fuel ratio of the main body 10 approaches a target air-fuel ratio based on the detection values ​​of the intake air flow rate sensor 17, the intake pressure sensor 18, and the sensor 19.

[0018] Furthermore, two electric motors are connected to the output shaft (crankshaft) of the main body 10: a starter motor 25, which is an electric motor for starting, and a motor generator 26, which is capable of electric travel and regenerative power generation. The starter motor 25 is, for example, a starter motor. The starter motor 25 and the motor generator 26 are electrically connected to a power source (not shown), and are drive-controlled by a control device 50. This allows the main body 10 to be started by either cranking, which uses the power of the starter motor 25 to increase the rotation speed Ne, or motoring, which uses the power of the motor generator 26 to increase the rotation speed Ne. Note that cranking start or motoring start may be selected as appropriate depending on various conditions.

[0019] (Ignition control for cranking start) Next, ignition control using the first spark plug 61 and the second spark plug 62 for cranking start of the main body 10 will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing an example of various control states and time changes in the air-fuel ratio (A / F), fuel injection amount, charging efficiency Ec, and rotation speed Ne when cranking start of the main body 10 is performed. Here, it is assumed that the rotation speed Ne of the main body 10 begins to increase due to cranking at time t1, initial combustion occurs after fuel injection and ignition start, and complete combustion occurs between time t2 and time t3. After time t1, the control device 50 executes various controls of the main body 10, including ignition control, for each of the following (1) first section to (4) fourth section.

[0020] (1) Section 1 The first section is a section that includes the initial explosion to the complete explosion after the start of the starting process of the main body 10. As described above, when the control device 50 starts the starting of the main body 10 at time t1, the control device 50 increases the rotation speed Ne of the main body 10 by cranking with the starter motor 25.

[0021] At this time, intake air flow rate sensor 17, intake pressure sensor 18, and sensor 19 are in an inactive (unactivated) state because they are just after the start of the main body 10. Therefore, the first section during cranking start can be said to be a section during which intake air flow rate sensor 17, intake pressure sensor 18, and sensor 19 are all inactive after the start processing of the main body 10 has begun. Therefore, control device 50 can only obtain the intake air amount and air-fuel ratio in main body 10 as estimated values ​​(for example, see the two-dot chain line for "A / F" in the figure) estimated based on the opening of throttle valve 8, the fuel injection amount, etc., and cannot execute the F / B control. Furthermore, the rotation speed Ne during cranking (between times t1 and t2) is relatively low (for example, 200 rpm), and the intake air amount becomes unstable.

[0022] In order to ensure initial combustion in the first section, the control device 50 executes a fuel increase process to increase the amount of fuel supplied (fuel injection amount) from the injector 9 to the main combustion chamber 40 as an air-fuel mixture compared to when the engine is not cranking, for a predetermined period of time after the start of the start process (time t1) including at least the cranking period. As a result, the amount of fuel in the main combustion chamber 40 increases compared to other sections. Also, since the pressure inside each cylinder 30 is approximately atmospheric immediately after the start process begins, the charging efficiency Ec tends to be relatively high (for example, a state close to when the throttle valve 8 is fully open with the turbocharger 15 not operating), and the air-fuel mixture tends to flow into the auxiliary combustion chamber 42.

[0023] As described above, in the first section, a sufficient amount of fuel is likely to be supplied to the pre-combustion chamber 42, and there is a low possibility of misfire occurring even when JET ignition is used by the second spark plug 62. Therefore, the control device 50 executes JET ignition by the second spark plug 62 in the first section. This enables high-speed combustion by JET ignition, improves the efficiency of the main body 10, suppresses the generation of unburned fuel, and also makes it possible to quickly achieve complete combustion from the initial explosion.

[0024] (2) Section 2 The second section is a transition section to idling operation of the main body 10 (for example, a section in which fast idling is performed to increase the rotation speed Ne to warm up the main body 10). More specifically, the second section is a section in which, after complete combustion of the main body 10, the intake air flow rate sensor 17 and the intake air pressure sensor 18 are activated and the intake air volume can be calculated from their detected values ​​(time t3), but the sensor 19 is inactive and the F / B control cannot be performed. Here, the air-fuel ratio can be estimated more accurately than in the first section based on the calculated intake air volume.

[0025] Furthermore, in the second section, the control device 50 executes ignition retard control as catalyst temperature rise control that raises the temperatures of the upstream side exhaust purification catalyst 12 and the downstream side exhaust purification catalyst 13. The ignition retard control is a control that delays the ignition timing of the air-fuel mixture compared to when catalyst temperature rise control is not executed, and raises the temperature of each catalyst by sending exhaust gas with a relatively high temperature to the upstream side exhaust purification catalyst 12 and the downstream side exhaust purification catalyst 13.

[0026] In this second section, the air-fuel ratio in the main combustion chamber 40 cannot be accurately controlled by F / B control, but the amount of fuel in the main combustion chamber 40 is at least reduced compared to the first section in which fuel increase processing was performed. Furthermore, the charging efficiency Ec is also reduced compared to the first section. As a result, the amount of fuel in the auxiliary combustion chamber 42 is reduced. Therefore, the control device 50 executes both SI ignition by the first spark plug 61 and JET ignition by the second spark plug 62. As a result, even if the mixture in the auxiliary combustion chamber 42 cannot be ignited by JET ignition, the mixture in the main combustion chamber 40 can be ignited by SI ignition, thereby suppressing misfires in the main body 10.

[0027] (3) Section 3 The third section is an idling operation section of the main body 10. More specifically, the third section is a state in which the sensor 19 is activated (time t5) after the complete explosion of the main body 10, and F / B control can be executed. In the example shown in FIG. 3, F / B control using the detection value of the sensor 19 is started at time t4, which is slightly earlier than time t5. However, here, the time t5 when the F / B control is generally stable is defined as the start of the third section (a section in which F / B control can be executed). However, the third section may also be defined to start from time t4. The control device 50 also executes ignition retard control as catalyst temperature rise control in the third section.

[0028] In this third section, the air-fuel ratio is controlled by F / B control so that the main combustion chamber 40 is in a stoichiometric state (see, for example, the solid line "A / F" in the figure). As a result, the amount of fuel in the auxiliary combustion chamber 42 becomes relatively small, creating a state unsuitable for JET ignition. Therefore, the control device 50 executes SI ignition using the first spark plug 61. This makes it possible to more reliably suppress misfires in the main body 10. Note that it is preferable that the explosion in the main combustion chamber 40 due to SI ignition occurs simultaneously with or after the injection of the flame F2 due to JET ignition.

[0029] Furthermore, by using SI ignition in this manner, it is possible to aim for slower combustion compared to JET ignition, and it is possible to raise the catalyst temperature more efficiently. Furthermore, in this embodiment, since the first ignition plug 61 is attached to the cylinder block 36 as described above, it is possible to further slow down combustion.

[0030] (4) Section 4 The fourth section is a normal operation section of the main body 10. More specifically, the fourth section is a section after the catalyst temperature rise from the state of the third section is completed (time t6). In such a fourth section, the control device 50 switches the ignition method for each operating range divided according to the load (which may be the charging efficiency Ec) and the rotation speed Ne. The control device 50 may pre-set a map that defines the ignition method for each operating range and select a method according to the current load and rotation speed Ne from the map. The map may be determined from various perspectives so as to be adaptable to both lean and rich combustion of the main combustion chamber 40 and the auxiliary combustion chamber 42, for example, by primarily using SI ignition when the fuel supply or ignition ability of the auxiliary combustion chamber 42 is poor, or by primarily using JET ignition when the state is suitable for high-speed combustion, or by changing the map according to the transient state of the main body 10. Furthermore, when both SI ignition and JET ignition are used, which one is ignited first may be appropriately set according to the state of the main body 10 and the control objective.

[0031] (Ignition control for motoring start) Next, ignition control using the first spark plug 61 and the second spark plug 62 for motoring start of the main body 10 will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing an example of various control states and time changes in the air-fuel ratio (A / F), fuel injection amount, charging efficiency Ec, and rotation speed Ne when motoring start of the main body 10 is performed. The solid lines in the figure indicate the fuel injection amount, charging efficiency Ec, and rotation speed Ne at the time of cranking start shown in Fig. 3.

[0032] Here, it is assumed that the rotational speed Ne of the main body 10 begins to increase due to motoring at time t1 and is maintained at a predetermined value, that initial explosion occurs after time t2, and that complete explosion occurs by time t3. In this case, the control device 50 does not perform ignition until the intake air flow sensor 17 and the intake air pressure sensor 18 become active and are able to calculate the intake air volume based on their detected values ​​(time t2). That is, in the (1) first section of motoring start, the air-fuel ratio can be estimated more accurately based on the calculated intake air volume than during cranking start, and there is no need to execute the fuel increase process as during cranking start. In other words, in the first section of motoring start, the amount of fuel supplied to the main combustion chamber 40 and the auxiliary combustion chamber 42 is less than during cranking start.

[0033] Therefore, when ignition occurs after time t2, the control device 50 executes SI ignition using the first spark plug 61. This makes it possible to achieve stable ignition by SI ignition during motoring start, which is a relatively low rotation speed and low load period and in which less fuel is supplied to the auxiliary combustion chamber 42 than during cranking start.

[0034] The subsequent control in the (2) second section to the (4) fourth section is the same as that described in FIG. 3, and therefore will not be described again. However, if the startability of the main body 10 is lower than normal, other ignition methods may be used. For example, if there is difficulty in supplying fuel to the auxiliary combustion chamber 42, such as when the main body 10 is idling or at low speed and low load, the pressure of the explosion caused by SI ignition may be used to push the mixture in the main combustion chamber 40 into the auxiliary combustion chamber 42, and then the mixture may be ignited by JET ignition. Also, for example, in an extremely low temperature environment where the ignitability of the fuel in the auxiliary combustion chamber 42 tends to be reduced, the area around the auxiliary combustion chamber 42 may be heated by the explosion caused by SI ignition, and the mixture may be ignited by JET ignition. In either case, at least the initial explosion of the main body 10 is performed by SI ignition.

[0035] (Effects of the embodiment) As described above, in the internal combustion engine system 1 of the embodiment, after the main body 10 has begun to start, the control device 50 executes a fuel increase process that increases the amount of fuel supplied to the main combustion chamber 40 more than during non-cranking for a predetermined period of time, including during cranking, which uses the starter motor 25 (electric motor) to increase the rotation speed Ne of the main body 10, and ignites the air-fuel mixture by the second spark plug 62 at the first explosion of the main body 10 (first section), and after the main body 10 has completely exploded, ignites the air-fuel mixture by both the first spark plug 61 and the second spark plug 62 during the transition process to idling operation (second section).

[0036] With this configuration, at the time of cranking start, JET ignition of the second ignition plug 62 is used to perform initial combustion, thereby achieving high-speed combustion, improving the efficiency of the main body 10, suppressing the generation of unburned fuel, and achieving a rapid transition to complete combustion. Furthermore, during the transition process to idling operation in which the amount of fuel in the auxiliary combustion chamber 42 is reduced compared to immediately after the start of startup, the use of SI ignition in addition to JET ignition can suppress the occurrence of misfires in the main body 10. Therefore, according to the internal combustion engine system 1 of this embodiment, it is possible to improve the efficiency and stability of combustion at the time of starting the main body 10 by using the first ignition plug 61 arranged in the main combustion chamber 40 and the second ignition plug 62 arranged in the auxiliary combustion chamber 42.

[0037] In addition, when the control device 50 executes catalyst temperature rise control of the upstream exhaust purification catalyst 12 and the downstream exhaust purification catalyst 13 provided in the exhaust passage 11 after the main body 10 is idling (third section), it ignites the mixture with the first ignition plug 61 while delaying the ignition timing compared to when catalyst temperature rise control is not executed, and when the control device 50 does not execute catalyst temperature rise control after the main body 10 is idling (fourth section), it switches the ignition method using the first ignition plug and the second ignition plug depending on the load and rotation speed.

[0038] This configuration ensures reliable ignition by SI ignition in Section 3, while accelerating catalyst temperature rise control by ignition retard control and slowing combustion by SI ignition. In Section 4, an ignition method according to the load and rotation speed Ne is used, allowing appropriate control to be performed from various perspectives, such as improving the efficiency of the main body 10 and combustion stability.

[0039] Furthermore, at the time of motoring start, in which the control device 50 does not execute the fuel increase control but keeps the rotation speed Ne of the main body 10 at a predetermined value using the motor generator 26 (electric motor) and then supplies fuel, the first spark plug 61 ignites the air-fuel mixture at the initial explosion. With this configuration, misfires in the main body 10 can be suppressed at the time of motoring start, in which the fuel increase process is not executed.

[0040] Furthermore, the control device 50 executes F / B control, which adjusts the intake air amount and fuel supply amount based on the detection value of the sensor 19 provided in the main body 10, so that the air-fuel ratio of the main body 10 approaches the target air-fuel ratio. During the transition process to idling (second section), the sensor 19 is inactive after complete combustion of the main body 10 and F / B control cannot be executed, and after idling (third and fourth sections), the sensor 19 is activated after complete combustion of the main body 10 and F / B control can be executed. With this configuration, each control section can be appropriately divided, and in the second section where F / B control cannot be executed, reliable ignition by SI ignition in addition to JET ignition can be aimed for, and in the third and fourth sections where F / B control can be executed, an ignition method according to the situation can be adopted.

[0041] Additionally, the first spark plug 61 is provided in the cylinder block 36, and the auxiliary combustion chamber 42 and the second spark plug 62 are provided in the cylinder head 34. This configuration makes it possible to more effectively slow combustion by SI ignition and promote catalyst temperature rise.

[0042] (Other spark plug arrangements) The positions of the first spark plug 61 and the second spark plug 62 are not limited to the example shown in FIG. 2. FIG. 5 is an explanatory diagram schematically showing another example of the positions of the first spark plug 61 and the second spark plug 62. In the cylinder 300 shown in FIG. 5, the first spark plug 61 is provided at the top of the main combustion chamber 40 (i.e., the cylinder head 34). Furthermore, an auxiliary combustion chamber 42, which is a space separated by a partition wall 44 attached to the cylinder block 36, is provided within the main combustion chamber 40, and the second spark plug 62 is disposed within the auxiliary combustion chamber 42. Even with such an arrangement of the first spark plug 61 and the second spark plug 62, the ignition control of the embodiment can achieve the above-described effects.

[0043] Furthermore, with the configuration shown in FIG. 5, the flame F1 generated by SI ignition can be pushed to the vicinity of the cylinder wall by the flame F2 generated by JET ignition, thereby also promoting the combustion of unburned fuel from the previous cycle that remained near the cylinder wall. By promoting the combustion of unburned fuel in this manner, the occurrence of knocking can be suppressed. The auxiliary combustion chamber 42 and the multiple communication holes 46 are positioned so that the injection direction of the flame F2 is generally along the extension direction of the surface of the piston 37 facing the main combustion chamber 40 (a direction perpendicular to the sliding direction of the piston 37). This makes it possible to suppress damage to the piston 37 caused by the flame F2. The size and number of the multiple communication holes 46 may be set according to the cylinder volume. In this embodiment, the multiple communication holes 46 are formed in a row along the depth direction of FIG. 2.

[0044] Although the description of the embodiment has been completed above, aspects of the present invention are not limited to this embodiment. For example, in the first section of cranking start, as long as at least the initial combustion is performed by JET ignition, other ignition methods may be used thereafter. Similarly, in the first section of motoring start, as long as at least the initial combustion is performed by SI ignition, other ignition methods may be used thereafter.

[0045] In this embodiment, SI ignition is performed in the idling operation section (third section). However, if catalyst temperature increase control is not performed after F / B control becomes executable, ignition by only JET ignition or ignition by both SI ignition and JET ignition may be performed even during idling operation, depending on the characteristics of the main body 10. In this case, the ignition method predetermined in the map may be used. [Explanation of symbols]

[0046] 1 Internal combustion engine system 10 Internal combustion engine body 19 Sensors 25 Starter motor (electric motor) 26 Motor generator (electric motor) 30, 300 cylinders 40 Main combustion chamber 42 Auxiliary combustion chamber 46 Communication hole 50 Control device 61 First spark plug (first ignition device) 62 Second spark plug (second ignition device)

Claims

1. a main combustion chamber filled with an air-fuel mixture; an auxiliary combustion chamber communicating with the main combustion chamber via a plurality of communication holes; a first ignition device disposed in the main combustion chamber and configured to ignite the air-fuel mixture in the main combustion chamber; a second ignition device disposed in the auxiliary combustion chamber and configured to ignite the air-fuel mixture in the auxiliary combustion chamber; an internal combustion engine body including: a control device that controls the internal combustion engine body; Equipped with The control device After the start of the internal combustion engine body, a fuel increase process is executed for a predetermined time period including a cranking period in which the rotation speed of the internal combustion engine body is increased using an electric motor, in order to increase the amount of fuel supplied compared to a non-cranking period; At the initial combustion of the internal combustion engine body, the second ignition device ignites the air-fuel mixture, an internal combustion engine system in which, after a complete explosion of the internal combustion engine body, the air-fuel mixture is ignited by both the first ignition device and the second ignition device during a process of transitioning to idling operation;

2. The control device When performing temperature rise control of a catalyst provided in an exhaust passage after the idling operation of the internal combustion engine body, the air-fuel mixture is ignited by the first ignition device while delaying ignition timing compared to when the temperature rise control is not performed, 2. The internal combustion engine system according to claim 1, wherein when the temperature rise control is not performed after the idling operation of the internal combustion engine body, the ignition method using the first ignition device and the second ignition device is switched depending on the load and the rotation speed.

3. 2. The internal combustion engine system according to claim 1, wherein the control device does not execute the fuel increase process, but instead uses the electric motor to maintain the rotation speed of the internal combustion engine body at a predetermined value before supplying fuel, and during motoring start, the control device ignites the air-fuel mixture by the first ignition device at the initial explosion.

4. the control device executes feedback control to adjust an intake air amount and a fuel supply amount based on a detection value of a sensor provided in the internal combustion engine body so that an air-fuel ratio of the internal combustion engine body approaches a target air-fuel ratio; The transition process to idling operation is in progress when the sensor is inactive after a complete explosion of the internal combustion engine body and the feedback control cannot be performed.

3. The internal combustion engine system according to claim 2, wherein the period after idling is a period after the internal combustion engine main body has completely exploded, in which case the sensor is activated and the feedback control can be performed.

5. the first ignition device is provided in a cylinder block of the internal combustion engine body, 5. The internal combustion engine system according to claim 1, wherein the auxiliary combustion chamber and the second ignition device are provided in a cylinder head of the internal combustion engine body.

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