Internal combustion engine system

Abstract

To provide an internal combustion engine system capable of more appropriately suppressing generation of deposit formed by accumulating unburned fuel by using an ignition device disposed in an auxiliary combustion chamber.SOLUTION: An internal combustion engine system includes: a body 10 that has a main combustion chamber 40 filled with an air-fuel mixture, an auxiliary combustion chamber 42 communicating with the main combustion chamber 40 via a plurality of communication holes and a second ignition plug 62 disposed in the auxiliary combustion chamber 42 to ignite the air-fuel mixture in the auxiliary combustion chamber 42; and a control device that controls the body 10. In operation stop processing of the body 10, the control device executes ignition by using the second ignition plug 62 for a predetermined period after stop of fuel supply.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine system having an ignition device arranged 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 disposed 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 such a way that a tumble vortex is easily formed 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 that a rich air-fuel mixture is filled in the auxiliary combustion chamber, and 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 the internal combustion engine is stopped. However, when the internal combustion engine is stopped, there is a risk that unburned fuel may remain, especially in the auxiliary combustion chamber, which has lower scavenging ability than the main combustion chamber, and it is necessary to properly remove the unburned fuel in order to suppress deposits caused by the thermal action of the remaining fuel.

[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 more appropriately suppress the formation of deposits of unburned fuel by using an ignition device arranged in a pre-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, and an auxiliary combustion chamber ignition device disposed 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 the control device, during a process of stopping operation of the internal combustion engine body, performs ignition by the auxiliary combustion chamber ignition device at least once over a predetermined period of time after stopping the fuel supply. [Effects of the Invention]

[0007] According to the internal combustion engine system of the present invention, it is possible to more appropriately suppress the formation of deposits of unburned fuel by using an ignition device disposed in the auxiliary combustion chamber. [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] FIG. 10 is an explanatory diagram showing how various control variables change over time when a neutral stop is performed. [Figure 4] FIG. 4 is an explanatory diagram showing how various control variables change over time when a motoring stop is performed. [Figure 5] FIG. 2 is an explanatory diagram showing an example of an ignition method when the internal combustion engine system according to the embodiment is applied to a hybrid vehicle. [Figure 6] 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) 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. In an intake passage 5 of the main body 10, an air cleaner 6, an intercooler 7, and a throttle valve 8 are provided upstream of the intake port 2 of each cylinder 30 along the flow of intake air. Meanwhile, in an exhaust passage 11 of the main body 10, an upstream exhaust purification catalyst 12 and a downstream exhaust purification catalyst 13 are provided along the flow of exhaust from the exhaust port 3 of each cylinder 30.

[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. A first ignition plug 61 (main chamber ignition device) that ignites the air-fuel mixture in the main combustion chamber 40 is provided at the top of the main combustion chamber 40 (i.e., the cylinder head 34).

[0014] Also, 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 cylinder block 36. 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 with each other 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 ignition plug 62 (auxiliary chamber ignition device) is disposed within the auxiliary combustion chamber 42, and 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"), as shown by the dashed dotted line in the figure, 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. In this way, stable ignition can be achieved by directly igniting the air-fuel mixture filled in the main combustion chamber 40.

[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"), flame F2 is injected from the auxiliary combustion chamber 42 through the multiple communication holes 46 into the main combustion chamber 40, as shown by the dashed line in the figure. 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 burn unburned fuel that was not ignited by SI ignition. Furthermore, flame F2 from JET ignition can push flame F1 generated by SI ignition to the vicinity of the cylinder wall, thereby also burning unburned fuel that remained near the cylinder wall in the previous cycle. By promoting the combustion of unburned fuel in this way, knocking can be suppressed.

[0017] The auxiliary combustion chamber 42 and the plurality of communication holes 46 are positioned so that the injection direction of the flame F2 is generally along the extension direction of the face 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 prevent the flame F2 from damaging the piston 37. The size and number of the plurality of communication holes 46 may be set according to the cylinder volume. In this embodiment, the plurality of communication holes 46 are formed side by side in the depth direction of FIG. 2.

[0018] 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, a storage device (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 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 amount from the injector 9, intake valve 32, exhaust valve 33, first spark plug 61, second spark plug 62, etc. based on the acquired information.

[0019] For example, the control device 50 may preset a map that defines an ignition method for each operating range of the main body 10, and select a method from the map according to the current load and rotation speed Ne. 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 if there are problems with fuel supply or ignition in the auxiliary combustion chamber 42, or by primarily using JET ignition if the condition is suitable for high-speed combustion, or by changing the map according to the transient state of the main body 10.

[0020] An ignition switch 27 is also connected to the control device 50, which allows a user of the internal combustion engine system 1 (for example, a vehicle driver) to instruct the main body 10 to start or stop operation. The control device 50 switches the main body 10 between starting and stopping operation based on a signal input from the ignition switch 27.

[0021] Furthermore, an electric motor 26 is connected to the output shaft (crankshaft) of the main body 10. The electric motor 26 is, for example, a motor generator capable of generating electricity using the power of the main body 10. The electric motor 26 is electrically connected to a power source (not shown), and is drive-controlled by the control device 50.

[0022] (Stop processing) Here, when stopping the operation of the main body 10, the control device 50 executes either a neutral stop or a motoring stop. The neutral stop is a process of stopping the supply of fuel to the main combustion chamber 40 and naturally reducing the rotation speed Ne of the main body 10. The neutral stop is executed, for example, when an operation stop signal is input to the control device 50 by the ignition switch 27 and the operation of the entire machine, such as a vehicle equipped with the internal combustion engine system 1, is stopped.

[0023] On the other hand, motoring stop is a process that stops the supply of fuel to the main combustion chamber 40, operates the electric motor 26 to generate regenerative electricity, and applies a braking force to the main body 10 to reduce the rotation speed Ne. As a result, in motoring stop, the rotation speed Ne of the main body 10 decreases at a rate greater than in neutral stop, making it possible to improve noise and vibration characteristics (NV characteristics). For example, when the internal combustion engine system 1 is mounted on a hybrid vehicle, motoring stop is performed when it becomes unnecessary to generate electricity by the electric motor 26 using the power of the main body 10.

[0024] (Ignition control for neutral stop) Next, ignition control during the shutdown process of the main body 10 will be described in the case of a neutral stop. FIG. 3 is an explanatory diagram showing the time changes of various control variables when a neutral stop is performed. Note that the "ON" and "OFF" of SI ignition and JET ignition in FIG. 3 and FIG. 4 described later do not represent the control signals themselves, but are simply shown as "ON" when the main body 10 is operating using the corresponding ignition method and "OFF" when the corresponding ignition method is not used. The actual ignition cycle may be set as appropriate, but the JET ignition cycle during the shutdown process described below may be set based on, for example, the rotation of the main body 10 (rotation of the crankshaft) that ignites all cylinders 30 at least once.

[0025] 3, it is assumed that at time t1, a request to stop the main body 10 by neutral stop is made ("ON" in the figure) to the main body 10, which has been operating with SI ignition by the first spark plug 61. In response to the stop request, the control device 50 stops the supply of fuel as an air-fuel mixture from the injector 9 to the main combustion chamber 40. As a result, the rotation speed Ne naturally decreases from time t1.

[0026] However, the control device 50 of this embodiment executes JET ignition by the second spark plug 62 for a first predetermined period Δt1 (predetermined period) from time t1. The first predetermined period Δt1 is determined as appropriate through experimentation and analysis as the time required for JET ignition to combust unburned fuel in the main combustion chamber 40 and the auxiliary combustion chamber 42. The first predetermined period Δt1 is, for example, the period from time t1 until the rotation speed Ne drops to a predetermined rotation speed Ne1 (time t2). The predetermined rotation speed Ne1 is the lower detection limit of a rotation speed sensor (not shown) that detects the rotation speed Ne (rotation speed of the crankshaft), and is, for example, approximately 200 rpm.

[0027] As a result, the unburned fuel remaining in the main combustion chamber 40 and the auxiliary combustion chamber 42 can be ignited and burned by the flame F2 injected by JET ignition. Note that, because fuel supply is stopped, even if JET ignition is performed, combustion does not occur in the main combustion chamber 40 to an extent that would prevent a decrease in the rotation speed Ne. In the example shown in FIG. 3, after JET ignition is completed, the rotation of the main body 10 stops at time t3, and the operation shutdown process of the main body 10 is completed. In the case of this neutral stop, the electric motor 26 does not need to be driven to either the power running side or the regenerative side.

[0028] (Ignition control for motoring stop) Next, the ignition control in the process of stopping the main body 10 will be described in the case of a motoring stop. Figure 4 is an explanatory diagram showing how various control variables change over time when a motoring stop is performed. Here, it is assumed that the main body 10, which was operating with SI ignition as in Figure 3, is requested to stop due to a motoring stop at time t1, and fuel supply from the injector 9 is stopped.

[0029] When performing a motoring stop, the control device 50 stops the fuel supply at time t1 and then drives the electric motor 26 to the powering side, i.e., the side that applies driving force to the main body 10, for a second predetermined period Δt2 (predetermined period). As a result, the rotation speed Ne of the main body 10 is maintained so as not to decrease from time t1 to the second predetermined period Δt2. In other words, the control device 50 delays the start of the decrease in the rotation speed Ne due to the motoring stop for the second predetermined period Δt2. The second predetermined period Δt2 is determined appropriately through experimentation and analysis as the time required for combusting unburned fuel in the main combustion chamber 40 and the auxiliary combustion chamber 42 by JET ignition.

[0030] Then, the control device 50 executes JET ignition by the second spark plug 62 during the second predetermined period Δt2. As a result, it becomes possible to ignite the unburned fuel remaining in the main combustion chamber 40 and the auxiliary combustion chamber 42 with the flame F2 injected by JET ignition. In this case, too, because the fuel supply is stopped, combustion does not occur in the main combustion chamber 40 to an extent that would cause the rotation speed Ne to increase due to JET ignition.

[0031] Thereafter, when the second predetermined period Δt2 has elapsed, the control device 50 ends the JET ignition (time t2) and drives the electric motor 26 to the regeneration side, that is, the side that applies a braking force to the main body 10. As a result, the rotation speed Ne of the main body 10 suddenly decreases at a rate that is greater than that in the case of a neutral stop, and the rotation of the main body 10 stops. In the example shown in Fig. 4, the rotation of the electric motor 26 stops at time t3, and the operation stop process of the main body 10 is completed.

[0032] (Effects of the embodiment) As described above, the control device 50 of the internal combustion engine system 1 of this embodiment executes JET ignition by the second spark plug 62 at least once over the first predetermined period Δt1 or the second predetermined period Δt2 after stopping the fuel supply during the operation shutdown process of the main body 10. This configuration makes it possible to burn unburned fuel during the operation shutdown process by JET ignition. Therefore, according to the internal combustion engine system 1 of this embodiment, it is possible to more appropriately suppress the formation of deposits of unburned fuel by using the second ignition plug 62 arranged in the auxiliary combustion chamber 42.

[0033] Furthermore, in neutral stop, the control device 50 executes ignition by the second spark plug 62 for a first predetermined period Δt1 from when fuel supply is stopped until the rotation speed of the main body 10 becomes equal to or lower than a predetermined rotation speed Ne1, and in motoring stop, the control device 50 executes ignition by the second spark plug 62 while suppressing a decrease in the rotation speed Ne of the main body 10 by the electric motor 26 for a second predetermined period Δt2 from when fuel supply is stopped, and after the predetermined period Δt has elapsed, the control device 50 causes the electric motor 26 to reduce the rotation speed Ne of the main body 10. With this configuration, unburned fuel can be combusted well in both neutral stop and motoring stop.

[0034] (JET ignition period adjustment method) Furthermore, the control device 50 may adjust the first predetermined period Δt1 and the second predetermined period Δt2 (appropriately referred to indistinguishably as the "predetermined period Δt") according to the state of the main body 10. For example, when the ignition method before the start of the operation shutdown process of the main body 10 (immediately before time t1) includes JET ignition (when only JET ignition is performed or when both SI ignition and JET ignition are performed), the control device 50 sets the predetermined period Δt to be shorter than when the ignition method before the start of the shutdown process was SI ignition only. This makes it possible to avoid unnecessary JET ignition during the operation shutdown process, thereby saving energy.

[0035] Furthermore, the control device 50 sets the predetermined period Δt shorter the higher the temperature of the main body 10 at the start of the shutdown process of the main body 10, and longer the lower the temperature. Similarly, the control device 50 sets the predetermined period Δt shorter the higher the air pressure at the start of the shutdown process, and longer the air pressure. The temperature of the main body 10 may be the temperature of the cooling water flowing through a cooling circuit (not shown) or the temperature of the lubricating oil flowing through a lubrication path (not shown), and may be detected by an appropriate sensor. The air pressure around the aircraft on which the main body 10 is mounted may be detected by an appropriate sensor.

[0036] In this way, under conditions where unburned fuel is unlikely to remain in the main combustion chamber 40 or the auxiliary combustion chamber 42, such as when the temperature of the main body 10 is high or the ambient air pressure is high, it is possible to conserve energy by not performing unnecessary jet ignition during the operation shutdown process. On the other hand, under conditions where unburned fuel is likely to remain, such as when the temperature of the main body 10 is low or the ambient air pressure is low, it is possible to more reliably combust the unburned fuel by performing jet ignition more frequently during the operation shutdown process.

[0037] Furthermore, if the main body 10 was idling before the start of the operation shutdown process, the control device 50 sets the predetermined period Δt shorter the shorter the idling time, and sets the predetermined period Δt longer the longer the idling time. As a result, if the idling time, during which unburned fuel is likely to remain in the main combustion chamber 40 or the auxiliary combustion chamber 42, is relatively short, unnecessary jet ignition is not performed during the operation shutdown process, thereby achieving energy savings. On the other hand, if the idling time has been long, the number of jet ignitions performed during the shutdown process is increased to combust the unburned fuel.

[0038] (Example of application to hybrid vehicles) Furthermore, when the internal combustion engine system 1 is installed in a hybrid vehicle, the control device 50 may execute jet ignition during the shutdown process according to FIG. 5. FIG. 5 is an explanatory diagram showing an example of an ignition method when the internal combustion engine system 1 of the embodiment is applied to a hybrid vehicle. The hybrid vehicle here is a vehicle capable of executing a series running mode in which the generator motor generates electricity using the power of the main body 10 while running on the power of another traction motor, a parallel running mode in which the main body 10 can run on the power of both the generator motor and the other traction motor, or an engine running mode in which the main body 10 runs on the power of only the main body 10. Note that the "pre-operation" in FIG. 5 refers to the operation performed before the main body 10 was shut down, "power generation operation" refers to the state in which the hybrid vehicle is generating electricity in the series running mode, and "running operation" refers to the state in which the hybrid vehicle is running on the power of the main body 10 in the parallel running mode or the engine running mode. Furthermore, the "number of times jet ignition is performed" refers to the relative frequency of jet ignition during the shutdown process and is proportional to the length of the predetermined period Δt. This example also includes a "none" pattern in which no jet ignition is performed during the stop process.

[0039] As shown in patterns (1) to (8), when the main body 10 is currently stopped and not in idling stop, coast stop, or fuel cut stop (described later), the control device 50 sets the number of times JET ignition is performed to be higher if the previous ignition method was SI ignition only, and sets the number of times JET ignition is performed to be lower if JET ignition is included. Also, when the previous operation of the main body 10 was idling operation as in patterns (1) and (2), the control device 50 sets the number of times JET ignition is performed to be higher compared to patterns (3) to (8).

[0040] Furthermore, as shown in pattern (9), when the previous operation of the main body 10 was idling and the current state of the main body 10 is idling stop, the control device 50 sets the number of times JET ignition is performed to be smaller than in the case of operation stop of pattern (1). Idling stop is a state in which operation of the main body 10 is stopped due to idling operation continuing for a predetermined period of time in a parked hybrid vehicle. In idling stop, there is a high possibility that operation of the main body 10 will be required to be resumed in a short period of time compared to the case of pattern (1), and therefore the number of times JET ignition is performed to combust unburned fuel may be set to be slightly smaller.

[0041] Furthermore, as shown in patterns (11) to (14), when the main body 10 is in a coast stop state or a fuel cut stop state, the control device 50 performs scavenging of the main body 10 without performing jet ignition. A coast stop is a state in which the operation of the main body 10 is stopped when the driver brakes the hybrid vehicle while it is running and the vehicle stops. A fuel cut stop is a state in which the fuel supply to the main body 10 is stopped and the vehicle stops running, for example, when the driver releases the accelerator pedal while the hybrid vehicle is running and decelerates. In such a coast stop or fuel cut stop, there is a high possibility that the main body 10 will be required to resume operation in a very short time compared to other patterns. Therefore, there is a low possibility that deposits will be generated from the remaining unburned fuel, and energy can be saved by not performing jet ignition.

[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. 6 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. 6, a pre-combustion chamber 42 separated by a partition wall 44 is provided at the top of the main combustion chamber 40 (i.e., the cylinder head 34), and the second spark plug 62 is disposed within the pre-combustion chamber 42. The first spark plug 61 is also provided in the cylinder block 36. 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] In the configuration shown in Fig. 6, 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 in the example shown in Fig. 2, in which 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 in the same way as with ignition timing retardation used in catalyst temperature rise control, for example.

[0044] Although the description of the embodiment has been completed, aspects of the present invention are not limited to this embodiment. For example, the present invention may be applied to an internal combustion engine body that does not include the first ignition plug 61 and that only includes the auxiliary combustion chamber 42 and the second ignition plug 62. [Explanation of symbols]

[0045] 1 Internal combustion engine system 10 Internal combustion engine body 26 Electric motor 30, 300 cylinders 40 Main combustion chamber 42 Auxiliary combustion chamber 46 Communication hole 50 Control device 61 No. 1 spark plug (main chamber ignition device) 62 Second spark plug (pre-chamber ignition device) Δt Predetermined period Δt1 First specified period Δt2 Second specified period

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; an auxiliary chamber 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 executes ignition by the pre-chamber ignition device at least once for a predetermined period of time after fuel supply is stopped during processing to stop operation of the internal combustion engine body.

2. an electric motor connected to the internal combustion engine body; stopping the operation of the internal combustion engine body includes a neutral stop in which fuel supply is stopped to reduce the rotation speed of the internal combustion engine body, and a motoring stop in which fuel supply is stopped and the electric motor is operated to reduce the rotation speed of the internal combustion engine body, The control device In the neutral stop, ignition by the auxiliary combustion chamber ignition device is performed at least once during the predetermined period from when fuel supply is stopped until the rotation speed of the internal combustion engine body becomes equal to or lower than a predetermined rotation speed, In the motoring stop, ignition is performed by the auxiliary chamber ignition device at least once while suppressing a decrease in the rotation speed of the internal combustion engine body by the electric motor for the predetermined period after fuel supply is stopped, and after the predetermined period has elapsed, the rotation speed of the internal combustion engine body is reduced by the electric motor.

10. The internal combustion engine system of claim 1.

3. a main chamber ignition device disposed in the main combustion chamber and configured to ignite the air-fuel mixture in the main combustion chamber; 3. The internal combustion engine system according to claim 1, wherein the control device sets the predetermined period to be shorter when an ignition method including ignition by the auxiliary ignition device is being executed before the start of the operation stop process than when ignition is being executed using only the main ignition device.

4. 3. The internal combustion engine system according to claim 1, wherein the control device sets the predetermined period to be shorter as the temperature of the internal combustion engine body at the start of the operation stop process is higher.

5. 3. The internal combustion engine system according to claim 1, wherein, when idling has been performed before the start of the operation stop process, the control device sets the predetermined period to be longer as the idling time is longer.

Images