Internal combustion engine system

Abstract

To provide an internal combustion engine system that enables more appropriate combustion corresponding to a transmission state of a transmission 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 is mounted to a vehicle and 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, a first ignition plug 61 disposed in the main combustion chamber 40 to ignite the air-fuel mixture in the main combustion chamber 40 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 to which a transmission 26 is connected; and a control device that controls the body 10. The control device switches an ignition method to the air-fuel mixture by using the first ignition plug 61 and the second ignition plug 62 in accordance with an operating state of the body 10 and a transmission state of the transmission.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 sub-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] A transmission that changes the output of an internal combustion engine mounted on a vehicle is connected to the engine at a predetermined gear ratio. 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 describe the relationship between the ignition device and the transmission connected to the engine. However, depending on the speed change state of the transmission, the target point for the combustion state of the internal combustion engine may change. Therefore, in order to achieve more appropriate combustion, it is necessary to perform ignition control according to the speed change state.

[0005] The present invention has been made in view of the above problems, and its purpose is to provide an internal combustion engine system that can achieve more appropriate combustion in accordance with the speed change state of the transmission 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-mentioned object, the internal combustion engine system of the present invention is mounted on a vehicle and includes a main combustion chamber filled with a mixture of air and fuel, an auxiliary combustion chamber connected to 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 is also provided with an internal combustion engine body to which a transmission is connected, and a control device that controls the internal combustion engine body, and the control device switches the ignition method of the mixture by the first ignition device and the second ignition device depending on the operating state of the internal combustion engine body and the shifting state of the transmission. [Effects of the Invention]

[0007] According to the internal combustion engine system of the present invention, it is possible to achieve more appropriate combustion that corresponds to the shifting state of the transmission by using a first ignition device arranged in the main combustion chamber and a second ignition device arranged 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 an example of the relationship between the operating range of the main body and fuel efficiency when SI ignition is used, using contour lines. [Figure 4] FIG. 10 is an explanatory diagram showing, by contour lines, an example of the relationship between the operating range of the main body and fuel efficiency when JET ignition is used. [Figure 5] FIG. 2 is an explanatory diagram showing an example of an ignition method when the transmission is a stepped transmission. [Figure 6] FIG. 2 is an explanatory diagram showing an example of an ignition method when the transmission is a continuously variable transmission. [Figure 7] FIG. 10 is an explanatory diagram showing another example of an ignition method when the transmission is a continuously variable transmission. [Figure 8] FIG. 10 is an explanatory diagram showing an example of ignition control when kickdown occurs. [Figure 9] FIG. 10 is an explanatory diagram showing an example of kick-down JET determination. [Figure 10] 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 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 gas 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] Furthermore, a transmission 26 that changes the speed of the force output from the main body 10 at a predetermined gear ratio is connected to the output shaft (crankshaft) of the main body 10. The transmission 26 may be a stepped automatic transmission, a stepped manual transmission, or a continuously variable transmission (CVT). The control device 50 acquires information on the current gear change state set by the transmission 26 (the gear stage if stepped, or the gear ratio if continuously variable). The transmission 26 may be drive-controlled by the control device 50, or may be controlled by another control device of the vehicle in which the internal combustion engine system 1 is mounted.

[0020] (Ignition control) FIG. 3 is an explanatory diagram showing an example of the relationship between the operating range of the main body 10 and fuel economy when SI ignition is used, using contour lines. FIG. 4 is an explanatory diagram showing an example of the relationship between the operating range of the main body 10 and fuel economy when JET ignition is used, using contour lines. FIGS. 3 and 4 show an example of the case where the main body 10 is operating in a steady state. Also, in FIGS. 3 and 4, the more inside the contour line is positioned within the frame, the better the fuel economy, and points P1 and P2 indicate the best fuel economy points. Thus, fuel economy varies for each operating range defined by the rotation speed Ne and torque (load) of the main body 10 depending on whether SI ignition or JET ignition is used. Therefore, it can be seen that, from the perspective of improving fuel economy alone, it is preferable to switch between SI ignition and JET ignition depending on the operating state of the main body 10.

[0021] Therefore, when the main body 10 is operated in a steady state, the control device 50 preliminarily sets a map that defines an ignition method for each operating range of the main body 10, and selects a method from the map according to the current rotation speed Ne and torque (load). The map may be determined from the perspective of improving fuel efficiency as described above, or may be determined from other perspectives. For example, it is preferable to consider adaptability to both lean and rich combustion of the main combustion chamber 40 and the auxiliary combustion chamber 42, such as mainly using SI ignition if the fuel supply or ignition ability of the auxiliary combustion chamber 42 is poor, or mainly using JET ignition if the state is suitable for high-speed combustion, or changing the method according to the transient state of the main body 10.

[0022] (Ignition control according to gear shift status: in the case of stepped transmission) Here, depending on the shift state of the transmission 26, the target point in the combustion state of the main body 10 may change. Therefore, to achieve more appropriate combustion, it is necessary to perform ignition control according to the shift state. Therefore, when the state of the main body 10 changes transiently, the control device 50 of the embodiment switches between SI ignition and JET ignition as follows, based on information on the shift state (gear stage) obtained from the transmission 26. First, FIG. 5 is an explanatory diagram showing an example of an ignition method when the transmission 26 is a stepped transmission. Note that the transmission 26 here may be either an automatic transmission or a manual transmission. In FIG. 5, the horizontal axis represents the vehicle speed of the vehicle on which the internal combustion engine system 1 is installed, the vertical axis represents the rotation speed Ne of the main body 10, and dashed lines represent shift lines corresponding to the first, second, third, and fourth gears of the transmission 26 ("1st," "2nd," "3rd," and "4th," respectively, in the figure). The area surrounded by the two-dot chain line in the figure is defined as an efficiency band B, which is a region where the main body 10 has good combustion efficiency.

[0023] Assume now that, as the vehicle accelerates, the main body 10 is driven while the gears of the transmission 26 are changed along the arrows A1 to A7 in the figure. First, when the main body 10 is driven at a predetermined low speed (gear position) as indicated by the arrows A1 to A4, the fuel supply amount changes from moment to moment, causing transient changes in the rotation speed Ne and the load, i.e., the state of the main body 10. More specifically, sudden transient changes often occur when the vehicle is driven at low speed and high load, such as when turning uphill. Therefore, the control device 50 executes JET ignition using the second spark plug 62 when the vehicle is in a predetermined low speed state. This allows the rotation speed Ne to be effectively increased by utilizing the high-speed combustion of JET ignition in situations where the state of the main body 10 is prone to transient changes. Furthermore, the generation of unburned fuel in transient states can be suppressed.

[0024] In contrast, as shown by arrows A5 to A7, when the main body 10 is operated at a predetermined high-speed gear position higher than the predetermined low-speed gear position, the state of the main body 10 is less likely to change transiently than at the predetermined low-speed gear position. After the vehicle reaches its maximum speed, only the traveling wind and rolling resistance act on the vehicle, and the state of the main body 10 becomes steady. Therefore, the control device 50 executes SI ignition using the first spark plug 61 at the predetermined high-speed gear position. This ensures stable combustion through reliable ignition by SI ignition and reduces in-cylinder heat loss compared to when JET ignition is used. Furthermore, by preventing combustion noise and vibration caused by JET ignition, it is possible to suppress discomfort to the driver of a vehicle traveling at high speeds where traveling noise and rotational fluctuations are small.

[0025] However, when the gear position is in a predetermined low-speed state and the rotation speed Ne of the main body 10 is in a predetermined high-speed range, the control device 50 executes both SI ignition and JET ignition. For example, as shown by arrows A8 and A9, assume that the main body 10 is operated at a rotation speed Ne in a low-speed position that is higher than that indicated by arrows A1 and A2. In such a low-speed, high-speed range, the explosion caused by JET ignition is likely to increase the in-cylinder pressure. Therefore, by consuming a portion of the fuel in the main combustion chamber 40 through SI ignition, it is possible to prevent the in-cylinder pressure from increasing beyond the upper limit due to JET ignition. Therefore, in this case, it is preferable to control the explosion caused by SI ignition to occur before the explosion caused by JET ignition.

[0026] Furthermore, the control device 50 executes both SI ignition and JET ignition when the gear position is in a predetermined high-speed state and the rotation speed Ne of the main body 10 is in a predetermined low-speed range. For example, as shown by arrows A10 and A11, assume that the main body 10 is operated at a lower rotation speed Ne in the high-speed range than the arrows A5 and A7. In such a high-speed, low-speed range, the transmission 26 may be set to a gear position that is too high for the rotation speed Ne, which may result in a lack of torque required by the main body 10 and a failure to smoothly increase the rotation speed Ne. Therefore, in this case, by using both SI ignition and JET ignition and achieving high-speed combustion through JET ignition, the rotation speed Ne can be quickly exceeded beyond the range in which it does not smoothly increase. The predetermined low-speed range, the predetermined high-speed range, the predetermined high-speed range, and the predetermined low-speed range may be appropriately divided based on various viewpoints, such as the combustion efficiency and combustion stability of the main body 10.

[0027] Furthermore, the control device 50 executes both SI ignition and JET ignition in the idling region IDL in the figure, regardless of the gear position of the transmission 26. As a result, during idling operation when the fuel supply and intake air volume are relatively low, SI ignition stabilizes combustion and reduces in-cylinder heat loss, while JET ignition effectively increases the rotation speed Ne through high-speed combustion. In other words, the characteristics of both SI ignition and JE ignition can be utilized.

[0028] (Ignition control according to gear shift status: in the case of continuously variable transmission) Next, Fig. 6 is an explanatory diagram showing an example of an ignition method when the transmission 26 is a continuously variable transmission. In Fig. 6, the horizontal axis represents the vehicle speed of the vehicle on which the internal combustion engine system 1 is mounted, and the vertical axis represents the rotation speed Ne of the main body 10. The main body 10 and the transmission 26 operate within the range enclosed by the dashed line. The range enclosed by the two-dot chain line in the figure is the efficiency band B.

[0029] Assume now that, as the vehicle accelerates, the main body 10 is operated while the transmission 26 changes its speed (gear ratio) along arrows A12 and A13 in the figure. When the main body 10 is operated at a predetermined low speed as indicated by arrow A12, the control device 50 executes JET ignition using the second spark plug 62. This allows for an effective increase in the rotation speed Ne through high-speed combustion and suppression of unburned fuel generation, similar to the case of a stepped transmission, in situations where the state of the main body 10 is prone to transient changes. On the other hand, when the main body 10 is operated at a predetermined high speed as indicated by arrow A13, the control device 50 executes SI ignition using the first spark plug 61. This allows for combustion stabilization, reduced in-cylinder heat loss, and suppression of combustion noise and vibration due to JET ignition, similar to the case of a stepped transmission.

[0030] Even in the case of a continuously variable transmission, the predetermined low-speed region and the predetermined high-speed region may be appropriately separated based on factors such as the combustion efficiency and combustion stability of the main body 10. Here, the region lower or higher than the variable line L1, indicated by the dashed-dotted line, is referred to as the "predetermined low-speed region," and the region higher or lower than the variable line L1 is referred to as the "predetermined high-speed region." The position of variable line L1 changes depending on a value that responds to the driver's acceleration request, such as the vehicle's APS opening (accelerator opening). Suppose that a sudden change in the APS opening causes variable line L1 to move to variable line L2. As a result, the predetermined low-speed region expands, and the ignition method of the main body 10, which had been operating along arrow A13, switches from SI ignition to JET ignition. As a result, the high-speed combustion of JET ignition can be utilized to effectively respond to the driver's acceleration request. Such variable lines L1, L2 may be set, for example, so as to temporarily move in a direction that widens the region of the predetermined low speed state if the rate of change in the APS opening is equal to or greater than a preset threshold value.

[0031] Furthermore, in the region where the main body 10 is idling, shown as an idling region IDL in the figure, the control device 50 executes both SI ignition and JET ignition regardless of the gear state of the transmission 26, similar to the example of a stepped transmission. Furthermore, although not shown, the control device 50 may execute both SI ignition and JET ignition when the rotation speed Ne is in a predetermined high rotation region at a predetermined low speed, or when the rotation speed Ne is in a predetermined low rotation region at a predetermined high speed, similar to the case of a stepped transmission. The predetermined high rotation region and the predetermined low rotation region may be appropriately distinguished.

[0032] (Another example of an ignition system for a continuously variable transmission) FIG. 7 is an explanatory diagram showing another example of an ignition method when the transmission 26 is a continuously variable transmission. As shown in the figure, two variable lines are predefined. The region lower or higher than the variable line L3 is defined as the "predetermined low-speed region," the region higher or lower than the variable line L4 is defined as the "predetermined high-speed region," and the region between the variable lines L3 and L4 is defined as the "predetermined intermediate region." The control device 50 then executes JET ignition in the predetermined low-speed region, SI ignition in the predetermined high-speed region, and both SI ignition and JET ignition in the predetermined intermediate region. As a result, when the main body 10 and the transmission 26 are operated in the predetermined intermediate region, as illustrated by arrow A14, combustion utilizing the characteristics of both SI ignition and JET ignition can be achieved. In other words, the method shown in FIG. 7 enables more precise adjustment of the combustion state depending on the speed change state of the transmission 26. Note that, in the case of a stepped transmission, a gear corresponding to the "predetermined intermediate state" may also be set in a similar manner.

[0033] (Ignition control that corresponds to the kickdown of the transmission) When a driver of a vehicle depresses the accelerator pedal heavily, a kickdown occurs in which the gear position of transmission 26 automatically drops, which can cause a sudden change in the operating point of main body 10. Therefore, when a kickdown occurs in transmission 26, control device 50 executes ignition control as follows. Note that although the description here focuses on a stepped automatic transmission, similar control can also be applied to continuously variable transmissions as long as a change in the gear state similar to a kickdown occurs.

[0034] Figure 8 is an explanatory diagram showing an example of ignition control when kickdown occurs. Note that the graphs for SI ignition and JET in Figure 8 are simply shown as "ON" when the ignition method is used and "OFF" when the ignition method is not used, and do not represent ignition signals.

[0035] Now, suppose that while the main body 10 is operating with SI ignition, the accelerator is depressed heavily at time t1 (see "APS [%]" in the figure), causing a kickdown in which the transmission 26 shifts from fourth gear to third gear. As a result, from time t1, the rotation speed Ne of the main body 10 increases rapidly, for example, to the first rotation speed Ne1 or higher. At this time, the control device 50 turns on the kickdown JET determination and executes JET ignition. Details of the kickdown JET determination will be described later, but it is sufficient that the ON / OFF state is switched based on the rate of change of the APS opening or the rate of change of the rotation speed Ne. This allows high-speed combustion by JET ignition to be used in response to the rapid increase in the rotation speed Ne of the main body 10, thereby stabilizing combustion. Furthermore, an increase in unburned fuel can be suppressed.

[0036] Thereafter, when the kickdown JET determination is turned OFF at time t2, SI ignition is performed again. Then, at time t3, the accelerator is again depressed heavily, causing a kickdown in which the transmission 26 shifts from third gear to third gear. As a result, from time t3, the rotation speed Ne of the main body 10 increases rapidly, for example, to the second rotation speed Ne2 or higher. This causes the control device 50 to turn the kickdown JET determination ON again, and perform JET ignition from time t3. Note that FIG. 8 shows an example in which the kickdown JET determination is turned OFF at time t4, but JET ignition is continued thereafter based on other conditions.

[0037] Next, switching on and off of the kick-down jet determination will be described with reference to Figure 9. Figure 9 is an explanatory diagram showing an example of the kick-down jet determination. Now, assume that the APS opening increases sharply when transmission 26 is set to fourth speed, third speed, or second speed.

[0038] The control device 50 sets the predetermined value of the APS speed (rate of change in accelerator opening [% / s]) for turning on the kickdown JET determination in fourth gear to a first predetermined value α1, sets the predetermined value in third gear to a second predetermined value α2 that is smaller than the first predetermined value α1, and sets the predetermined value in second gear to a third predetermined value α3 that is smaller than the second predetermined value α2. As a result, in fourth gear, the APS speed becomes equal to or greater than the first predetermined value α1 at time t11, and the kickdown JET determination is turned on until time t12. In third gear, the APS speed becomes equal to or greater than the second predetermined value α2 at time t13, and the kickdown JET determination is turned on until time t14. In second gear, the APS speed becomes equal to or greater than the first predetermined value α1 at time t15, and the kickdown JET determination is turned on until time t16.

[0039] In this way, the predetermined value is set so that the smaller the gear ratio, the more likely the kick-down jet determination is to be on. In other words, the more likely the rotation speed Ne of the main body 10 is to be high, the more likely the kick-down jet determination is to be on. This makes it possible to more appropriately use high-speed combustion by jet ignition in response to an increase in the rotation speed Ne of the main body 10. Note that the transition of the kick-down jet determination from on to off may be based on, for example, the fact that the amount or rate of change in the APS opening or the rotation speed Ne remains below a certain value for a predetermined duration.

[0040] (Effects of the embodiment) As described above, the internal combustion engine system 1 of the embodiment is mounted on a vehicle and includes a main combustion chamber 40 filled with a mixture of air and fuel, an auxiliary combustion chamber 42 communicating with the main combustion chamber 40 via a plurality of communication holes, a first ignition plug 61 (first ignition device) arranged in the main combustion chamber 40 and igniting the mixture in the main combustion chamber 40, and a second ignition plug 62 (second ignition device) arranged in the auxiliary combustion chamber 42 and igniting the mixture in the auxiliary combustion chamber 42, a main body 10 (internal combustion engine main body) to which a transmission 26 is connected, and a control device 50 that controls the main body 10. The control device 50 switches the method of igniting the mixture by the first ignition plug 61 and the second ignition plug 62 depending on the operating state of the main body 10 and the gear shift state of the transmission 26.

[0041] With this configuration, not only the operating state of the main body 10 but also the speed change state is taken into consideration, so even if the operating state of the main body 10 is the same, if the speed change state is different, an ignition method appropriate for the speed change state can be used. Therefore, according to the internal combustion engine system 1 of the embodiment, it is possible to achieve more appropriate combustion corresponding to the speed change state of the transmission 26 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.

[0042] Furthermore, when the speed change state is in a predetermined low speed state, the control device 50 ignites the air-fuel mixture with the second spark plug 62, and when the speed change state is in a predetermined high speed state, the control device 50 ignites the air-fuel mixture with the first spark plug 61. With this configuration, when the speed change state is in a predetermined low speed state, JET ignition is used to quickly increase the rotation speed Ne and suppress the generation of unburned fuel, and when the speed change state is in a predetermined high speed state, SI ignition is used to stabilize combustion and reduce in-cylinder heat loss.

[0043] Furthermore, when the main body 10 is idling, the control device 50 ignites the air-fuel mixture by both the first spark plug 61 and the second spark plug 62, regardless of the gear shift state. With this configuration, it is possible to utilize the characteristics of both SI ignition and JE ignition to stabilize combustion during idling when the fuel supply and intake air amounts are relatively small, reduce in-cylinder heat loss, and increase the rotation speed Ne.

[0044] Furthermore, the control device 50 changes the ignition method depending on the operating state of the main body 10 and the gear shift state of the transmission 26 when the vehicle is accelerating. This configuration enables a rapid increase in the rotation speed Ne through JET ignition at a predetermined low speed, allowing the vehicle to accelerate smoothly. Furthermore, for example, when the vehicle is accelerating in a way that causes kickdown of the transmission 26, high-speed combustion through JET ignition can stabilize combustion.

[0045] Furthermore, when the gear shift state is a predetermined low speed state and the rotation speed Ne of the main body 10 is in a predetermined high rotation range, the control device 50 ignites the air-fuel mixture by both the first spark plug 61 and the second spark plug 62. With this configuration, in the low-speed, high rotation range, SI ignition can be used in combination with JET ignition to suppress excessive increases in in-cylinder pressure.

[0046] Furthermore, when the speed change state is a predetermined high speed state and the rotation speed Ne of the main body 10 is in a predetermined low rotation range, the control device 50 ignites the air-fuel mixture by both the first spark plug 61 and the second spark plug 62. With this configuration, by using JET ignition in combination with SI ignition in the low-speed, high rotation range, it is possible to quickly exceed the range in which the rotation speed Ne of the main body 10 does not increase smoothly.

[0047] (Other examples of the arrangement of the first and second spark plugs) 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. 10 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. 10, 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.

[0048] 10, the flame F1 generated by SI ignition is set to spread in the direction of extension of the surface of the piston 37. In this configuration, the flame F1 propagates a longer distance within the main combustion chamber 40 than in the example in which the flame F1 generated by SI ignition spreads from the center of the main combustion chamber 40 as shown in FIG. 2. 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.

[0049] Although the description of the embodiment has been completed, aspects of the present invention are not limited to this embodiment. For example, in this embodiment, the switching of ignition methods was described, mainly assuming acceleration of a vehicle equipped with the internal combustion engine system 1. However, similar switching of ignition methods may also be performed during steady driving or deceleration of the vehicle, or a different ignition method may be used during steady driving or deceleration. For example, as described above, ignition methods corresponding to operating ranges in the steady state of the main body 10 are defined in advance using a map. Then, the map may be modified so that the operating range in which JET ignition is primarily used is larger in the predetermined low-speed state, and the operating range in which SI ignition is primarily used is larger in the predetermined high-speed state. The combustion state to be targeted by the main body 10 changes depending on the specifications and characteristics of the vehicle, the main body 10, and the transmission 26. An ignition method may be adopted according to the load, engine speed Ne, and gear state for each target.

[0050] In addition, for example, when fuel cut control that stops fuel supply due to the accelerator being released while the vehicle is running is started or stopped (when fuel supply is restored), the state of the main body 10 changes suddenly. The ignition method may be switched in response to such a transient sudden change in the state of the main body 10. [Explanation of symbols]

[0051] 1 Internal combustion engine system 10 Internal combustion engine body 26 Transmission 30 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. It is mounted on a vehicle, 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 to which a transmission is connected; a control device that controls the internal combustion engine body; Equipped with The control device switches the ignition method for the air-fuel mixture by the first ignition device and the second ignition device depending on the operating state of the internal combustion engine body and the speed change state of the transmission.

2. 2. The internal combustion engine system according to claim 1, wherein the control device ignites the air-fuel mixture by the second ignition device when the speed change state is in a predetermined low speed state, and ignites the air-fuel mixture by the first ignition device when the speed change state is in a predetermined high speed state.

3. 3. The internal combustion engine system according to claim 1, wherein the control device ignites the air-fuel mixture by both the first ignition device and the second ignition device regardless of the gear shift state when the internal combustion engine body is idling.

4. 3. The internal combustion engine system according to claim 2, wherein the control device changes the ignition method in accordance with the operating state of the internal combustion engine body and the speed change state of the transmission when the vehicle is accelerating.

5. 3. The internal combustion engine system according to claim 2, wherein the control device ignites the air-fuel mixture by both the first ignition device and the second ignition device when the speed change state is the predetermined low speed state and the rotation speed of the internal combustion engine body is in a predetermined high rotation range.

6. 3. The internal combustion engine system according to claim 2, wherein the control device ignites the mixture by both the first ignition device and the second ignition device when the speed change state is the predetermined high speed state and the rotation speed of the internal combustion engine body is in a predetermined low rotation range.

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