Control system for divided-chamber type internal combustion engine

Abstract

This control system is for a divided-chamber type internal combustion engine having a main combustion chamber and a sub combustion chamber that is provided separate from the main combustion chamber by a wall. The control system comprises: an ignition device disposed in the sub combustion chamber; and a control device that controls the ignition device. The ignition device can change the electric discharge time between a first time and a second time longer than the first time, and can change the discharged electric current between a first electric current and a second electric current higher than the first electric current. The control device causes the electric discharge to occur for the second time when the divided-chamber type internal combustion engine is being operated at a low load, and causes the electric discharge to occur for the first time at the second electric current when the divided-chamber type internal combustion engine is being operated at a high load.

Description

Control system for pre-chamber internal combustion engines

[0001] The present disclosure relates to a control system for an internal combustion engine with a separate combustion chamber.

[0002] Conventionally, a pre-combustion chamber type internal combustion engine is known (see, for example, Patent Document 1). The pre-combustion chamber type internal combustion engine includes a main combustion chamber and a pre-combustion chamber, and ignites the air-fuel mixture in the main combustion chamber by injecting a flame from the pre-combustion chamber toward the main combustion chamber.

[0003] Japanese Patent Application Laid-Open No. 2006-316715

[0004] In such a pre-combustion chamber type internal combustion engine, there is a risk of misfire due to variations in the air-fuel mixture in the pre-combustion chamber.

[0005] An object of the present disclosure is to provide a control system for a pre-chamber internal combustion engine that can suppress misfires.

[0006] One aspect of the control system for a pre-combustion chamber internal combustion engine according to the present disclosure is a control system for a pre-combustion chamber internal combustion engine having a main combustion chamber and a pre-combustion chamber separated from the main combustion chamber by a wall, the control system comprising an ignition device disposed in the pre-combustion chamber and a control device that controls the ignition device, wherein the ignition device is capable of changing the discharge time between a first time and a second time longer than the first time, and is capable of changing the discharge current between a first current and a second current higher than the first current, and the control device discharges for the second time when the pre-combustion chamber internal combustion engine is operated under low load, and discharges the second current for the first time when the pre-combustion chamber internal combustion engine is operated under high load.

[0007] According to another aspect of the control system for a pre-combustion chamber internal combustion engine of the present disclosure, there is provided a control system for a pre-combustion chamber internal combustion engine having a main combustion chamber and an auxiliary combustion chamber separated from the main combustion chamber by a wall, the control system comprising an ignition device disposed in the auxiliary combustion chamber and a control device that controls the ignition device, wherein the ignition device is capable of changing the discharge time to a first time or a second time that is longer than the first time, and when the pre-combustion chamber internal combustion engine is started, the control device discharges current to the ignition device multiple times to implement the second time.

[0008] According to the control system for an internal combustion engine with a pre-combustion chamber of one aspect of the present disclosure, stable ignition can be achieved by varying the discharge current and discharge time in accordance with the rotation speed and load of the pre-combustion engine, thereby suppressing misfires.

[0009] According to another aspect of the control system for a pre-ignition chamber internal combustion engine of the present disclosure, stable ignition can be achieved by discharging the spark multiple times when the pre-ignition chamber internal combustion engine is started, thereby making it possible to suppress misfires when the pre-ignition chamber internal combustion engine is started.

[0010] Fig. 1 is a cross-sectional view of an internal combustion engine with a pre-combustion chamber according to a first embodiment of the present disclosure. Fig. 2 is a system diagram of an ignition device portion of a control system according to a first embodiment of the present disclosure. Fig. 3 is an overall system diagram of a control system according to a first embodiment of the present disclosure. Fig. 4 is a diagram showing a discharge pattern due to multiple discharges according to a first embodiment of the present disclosure. Fig. 5 is a diagram showing a discharge pattern due to a single discharge according to a first embodiment of the present disclosure. Fig. 6 is a diagram showing a map showing a discharge form with respect to engine rotation and load according to a first embodiment of the present disclosure. Fig. 7 is a diagram showing a discharge pattern due to multiple discharges according to a second embodiment of the present disclosure. Fig. 8 is a system diagram of a vehicle according to a third embodiment of the present disclosure. Fig. 9 is a flowchart showing a control procedure executed by an engine control device according to a third embodiment of the present disclosure.

[0011] First Embodiment A first embodiment of the present disclosure will be described below with reference to the drawings.

[0012] As shown in FIG. 1 , the auxiliary combustion chamber type internal combustion engine 1 has a main combustion chamber 4 , an auxiliary combustion chamber 6 , a plurality of communication passages 8 , an ignition plug (an example of an ignition device) 10 , and a fuel injection valve 12 .

[0013] The main combustion chamber 4 is a space surrounded by the cylinder 101a of the cylinder block 101, the cylinder head 102, and the piston 103. In this embodiment, the main combustion chamber 4 has a pent roof shape, with two slopes formed toward the intake port 105 side and the exhaust port 110 side of the cylinder head 102. The main combustion chamber 4 is connected to the intake port 105 via an intake valve 104. The main combustion chamber 4 is connected to the exhaust port 110 via an exhaust valve 109.

[0014] The intake port 105 is connected to, for example, the intake passage 24 (see FIG. 3), the throttle valve 26 (see FIG. 3), the intercooler 28 (see FIG. 3), and the air cleaner 30 (see FIG. 3). However, the pre-chamber internal combustion engine 1 need only be able to supply intake air to the intake port 105, and may not, for example, be equipped with the intercooler 28. The intake valve 104 is driven by an intake cam (not shown). The exhaust port 110 is connected to the exhaust passage 32 (see FIG. 3) and the exhaust purification catalyst 34 (see FIG. 3). The exhaust valve 109 is driven by an exhaust cam (not shown).

[0015] The auxiliary combustion chamber 6 is located adjacent to the main combustion chamber 4 at the top of the pent roof shape and has a space surrounded by an auxiliary combustion chamber wall 61. The auxiliary combustion chamber 6 protrudes from the cylinder head 102 toward the main combustion chamber 4 and is separated from the main combustion chamber 4 by the auxiliary combustion chamber wall 61. In this embodiment, the auxiliary combustion chamber 6 is located approximately at the center of the intersection line (ridge line) of the slopes of the pent roof shape of the main combustion chamber 4. However, the auxiliary combustion chamber 6 may also be located offset from approximately the center of the main combustion chamber 4 toward the inner wall surface of the cylinder 101a. In this embodiment, the auxiliary combustion chamber wall 61 has, for example, a circular cross section and a hemispherical bottom 61a. However, the auxiliary combustion chamber wall 61 is not limited to this and can be modified into various shapes.

[0016] The spark plug 10 is provided in approximately the center of the pre-combustion chamber 6 and ignites the air-fuel mixture in the pre-combustion chamber 6. A central electrode 10a of the spark plug 10 protrudes into the pre-combustion chamber 6. In this embodiment, the central electrode 10a is provided in approximately the center of the pre-combustion chamber 6. However, the central electrode 10a may be positioned offset from approximately the center of the pre-combustion chamber 6.

[0017] A plurality of communication passages 8 are provided in the bottom 61a of the auxiliary combustion chamber wall 61. The communication passages 8 connect the main combustion chamber 4 and the auxiliary combustion chamber 6, and guide the air-fuel mixture in the main combustion chamber 4 to the auxiliary combustion chamber 6. In this embodiment, for example, six communication passages 8 are provided.

[0018] The volume of the auxiliary combustion chamber 6 is smaller than that of the main combustion chamber 4, and the flame of the air-fuel mixture ignited by the spark plug 10 propagates quickly into the auxiliary combustion chamber 6. The flame generated in the auxiliary combustion chamber 6 is injected into the main combustion chamber 4 via the communication passage 8. The flame injected into the main combustion chamber 4 ignites and burns the air-fuel mixture in the main combustion chamber 4. That is, in the auxiliary combustion chamber internal combustion engine 1, the combustion space 3 is formed by including the main combustion chamber 4 and the auxiliary combustion chamber 6.

[0019] The fuel injection valve 12 is provided facing the main combustion chamber 4 and injects fuel into the main combustion chamber 4. The fuel injection valve 12 is disposed on the intake valve 104 side of the cylinder head 102. The fuel injection valve 12 supplies fuel in a spray form to form an air-fuel mixture in the main combustion chamber 4. The fuel injection valve 12 also injects fuel into the main combustion chamber 4, thereby supplying the fuel to the auxiliary combustion chamber 6 via the communication passage 8. The fuel injection valve 12 supplies fuel to the auxiliary combustion chamber 6 to form an air-fuel mixture in the auxiliary combustion chamber 6. In this embodiment, the tip of the fuel injection valve 12 faces the main combustion chamber 4 and injects fuel directly into the main combustion chamber 4. That is, the auxiliary combustion chamber internal combustion engine 1 of this embodiment is a direct injection type internal combustion engine. However, the auxiliary combustion chamber internal combustion engine 1 may also be a port injection type internal combustion engine. The fuel injection valve 12 is electrically connected to a control device 18, and the injection amount and injection timing are controlled by the control device 18.

[0020] As shown in FIG. 2 , the control system 2 includes a first coil 14, a second coil 16, and a control device 18, and is a system for controlling the ignition energy supplied to the spark plug 10. As shown in FIG. 3 , the control system 2 for the pre-combustion chamber internal combustion engine 1 may also include a supercharger 17, an exhaust gas recirculation system 20, various devices for improving the performance of the pre-combustion chamber internal combustion engine 1, and sensors for detecting the state of the pre-combustion chamber internal combustion engine 1, such as an airflow sensor 22. In this embodiment, the pre-combustion chamber internal combustion engine 1 is an in-line internal combustion engine in which multiple cylinders are arranged in series. The main combustion chamber 4, the auxiliary combustion chamber 6, multiple communication passages 8, the spark plug 10, and the fuel injection valve 12 are provided for each of the in-line cylinders. However, the cylinder arrangement is not limited to this, and the pre-combustion chamber internal combustion engine 1 may be a V-type or horizontally opposed type.

[0021] The first coil 14 and the second coil 16 repeatedly store and discharge electricity to supply ignition energy (also referred to as discharge energy) to the spark plug 10. In the first embodiment, the first coil 14 and the second coil 16 are formed by coils having the same characteristics.

[0022] The first coil 14 and the second coil 16 are electrically connected to a control device 18. The control device 18 changes the discharge time and discharge current of the spark plug 10 by controlling the charge storage time and discharge time of the first coil 14 and the second coil 16. The control device 18 is actually an ECU (Electronic Control Unit) configured by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc.

[0023] 4A shows a discharge pattern in which the control device 18 simultaneously discharges the first coil 14 and the second coil 16 multiple times. As shown at time t1 in FIG. 4A, the control device 18 stores ignition energy in the first coil 14 and the second coil 16 until time t1, and then discharges the ignition energy at time t1. By overlapping the ignition energy of the first coil 14 and the ignition energy of the second coil 16 in this manner, a peak current Ap (an example of a second current) flows through the spark plug 10. The peak current Ap is higher than the normal current An (an example of a first current) that would flow if the spark were discharged only through the first coil 14 or the second coil 16.

[0024] As shown in Figure 4A from time t2 to time t3, the control device 18 stores electricity in the first coil 14 and the second coil 16 between time t2 and time t3. At time t3, the control device 18 discharges the first coil 14 and the second coil 16 again. In this second discharge, the ignition energy of the first coil 14 and the ignition energy of the second coil 16 are overlapped, causing a peak current Ap to flow through the spark plug 10. Hereinafter, this discharge pattern will be referred to as the first discharge pattern.

[0025] In this embodiment, at time t1, both the first coil 14 and the second coil 16 are sufficiently charged. However, the charge storage time from time t2 to time t3 is shorter than the charge storage time before time t1. Therefore, the second peak current Ap2 is lower than the first peak current Ap1. However, by controlling the charge storage and discharge of the first coil 14 and the second coil 16 in this manner, the control device 18 can generate the peak current Ap multiple times (two times in this embodiment) between time t1 and time t4.

[0026] 4B shows a discharge pattern in which the control device 18 alternately discharges the first coil 14 and the second coil 16 multiple times. As shown in FIG. 4B, at time t1, the control device 18 discharges the first coil 14, and at time t2, when the discharge of the first coil 14 is completed, the control device 18 discharges the second coil 16. The control device 18 stores electricity in the first coil 14 between time t2 and time t3, and performs a second discharge at time t3. The control device 18 stores electricity in the second coil 16 from after the discharge of the second coil 16 is completed until time t4, and performs a second discharge of the second coil 16 at time t4, when the second discharge of the first coil 14 is completed, and finishes discharging at time t5.

[0027] By alternately discharging the first coil 14 and the second coil 16 in this manner, the normal current An continues to flow through the spark plug 10 from time t1 to time t3 (an example of the second time). This allows the normal current An to continue to be discharged for a longer period of time than the time required for the first coil 14 and the second coil 16 to be discharged once (an example of the first time), which is shown as time t1 to time t2 in FIG. 4B. In this embodiment, by discharging twice, the normal current An continues to flow through the spark plug 10 from time t1 to time t5. Hereinafter, this discharge pattern will be referred to as the second discharge pattern.

[0028] As shown in Fig. 4, the normal current An and the peak current Ap have the highest current values ​​immediately after discharge and gradually decrease as the discharge time progresses. The actual normal current An and peak current Ap change in a fine undulating manner (see Fig. 6). Therefore, in this embodiment, the normal current An and the peak current Ap do not represent the current values, but represent the waveforms of such currents. The same applies to Figs. 5 and 7 described below.

[0029] 5A shows a discharge pattern in which the control device 18 alternately causes the first coil 14 and the second coil 16 to perform single discharges. As shown in FIG. 5A, the control device 18 causes the first coil 14 to discharge at time t1, causes the second coil 16 to discharge at time t2 when the discharge of the first coil 14 is completed, and ends the discharge at time t3. By alternately discharging the first coil 14 and the second coil 16 in this manner, normal current An continues to flow through the spark plug 10 for the period from time t1 to time t3 (an example of a second time), which is longer than the period from time t1 to time t2 (an example of a first time) in FIG. 5 (charge b). Hereinafter, this discharge pattern will be referred to as a third discharge pattern.

[0030] 5B shows a discharge pattern in which the control device 18 simultaneously causes a single discharge from the first coil 14 and the second coil 16. As shown in FIG. 5B, the control device 18 discharges the ignition energy from the first coil 14 and the second coil 16 at time t1. By overlapping the ignition energy from the first coil 14 and the ignition energy from the second coil 16 in this manner, a peak current Ap (an example of the second current) flows through the spark plug 10 from time t1 to time t2. Hereinafter, this discharge pattern will be referred to as a fourth discharge pattern.

[0031] Next, the combination of discharge patterns executed by the control device 18 will be described with reference to FIG.

[0032] In Fig. 6, the vertical axis represents the load Ec, and the horizontal axis represents the rotational speed Ne. In this embodiment, the load Ec is represented by the charging efficiency. As shown in Fig. 5, when the pre-chamber internal combustion engine 1 is operated at low rotation speed and low load, the control device 18 causes the spark plug 10 to discharge the second current multiple times. In this embodiment, the control device 18 controls the charge storage and discharge of the first coil 14 and the second coil 16, executes the first discharge pattern shown in Fig. 4(a), and causes the spark plug 10 to discharge the peak current Ap multiple times.

[0033] When the pre-combustion chamber internal combustion engine 1 is operated at low speed and low load, the flow in the pre-combustion chamber 6 is weak, preventing premixing of the burned gas from the previous cycle with fresh air, resulting in a stratified mixture. This tendency is particularly pronounced in a passive pre-combustion chamber internal combustion engine 1, such as the present embodiment, which supplies the mixture from the main combustion chamber 4 to the pre-combustion chamber 6. For this reason, ignition performance is poor when the pre-combustion chamber internal combustion engine 1 is operated at low speed and low load. However, by having the spark plug 10 discharge according to the first discharge pattern, ignition performance is improved and misfires are more easily suppressed.

[0034] When the pre-combustion engine 1 is operating at high speed and low load, the control device 18 discharges the first current for a second period of time. In this embodiment, the control device 18 controls the charge storage and discharge of the first coil 14 and the second coil 16 to execute the second discharge pattern shown in Fig. 4(b) or the third discharge pattern shown in Fig. 5(a) and causes the spark plug 10 to discharge the normal current An for a long period of time.

[0035] When the pre-combustion chamber type internal combustion engine 1 is operated at high speed and low load, the air-fuel mixture in the pre-combustion chamber 6 tends to vary greatly. This tends to result in a variation in combustion distribution at the time of ignition. Therefore, when the pre-combustion chamber type internal combustion engine 1 is operated at high speed and low load, the control device 18 causes the spark plug 10 to discharge for a long period of time, thereby suppressing the variation in combustion distribution and achieving more uniform combustion in the pre-combustion chamber 6.

[0036] When the pre-chamber internal combustion engine 1 is operating under high load, the control device 18 discharges the second current for a first period of time, regardless of whether the engine is running at low or high speed. In this embodiment, the control device 18 controls the charge and discharge of the first coil 14 and the second coil 16, executes the fourth discharge pattern shown in Fig. 5(b), and discharges the peak current Ap for a short period of time.

[0037] When the pre-combustion chamber type internal combustion engine 1 is operated under high load, the flow in the pre-combustion chamber 6 is high, which promotes the mixing of the air-fuel mixture. Therefore, when the pre-combustion chamber type internal combustion engine 1 is operated under high load, the control device 18 causes the ignition plug 10 to discharge a peak current Ap, thereby quickly igniting the fuel and promoting combustion in the pre-combustion chamber 6.

[0038] In this way, the control device 18 changes the discharge pattern according to the rotation speed and load of the pre-combustion chamber type internal combustion engine 1. This allows the mixture in the pre-combustion chamber 6 to be ignited appropriately according to the rotation speed and load. As a result, the control system 2 can suppress misfires. The low rotation speed may be, for example, less than half the maximum rotation speed of the pre-combustion chamber type internal combustion engine 1. The high rotation speed may be, for example, more than half the maximum rotation speed of the pre-combustion chamber type internal combustion engine 1. The low load may be, for example, less than half the maximum output of the pre-combustion chamber type internal combustion engine 1. The high load may be, for example, more than half the maximum output of the pre-combustion chamber type internal combustion engine 1.

[0039] Second Embodiment Next, a second embodiment will be described with reference to Fig. 7. In the second embodiment, only the differences from the first embodiment will be described. As shown in Fig. 7, the second embodiment differs from the first embodiment in that the first coil 14 and the second coil 16 are formed by coils having different characteristics.

[0040] 7A, the first coil 14 has coil characteristics that allow it to generate a peak current Ap (an example of the second current) from time t1 to time t2 (an example of the first time) in one discharge. As shown in FIG. 7B, the second coil 16 has coil characteristics that allow it to generate a normal current An (an example of the first current) in one discharge from time t1 to time t3 (an example of the second time), which is longer than time t2.

[0041] The control device 18 forms the first discharge pattern shown in Figures 4 and 5 by switching between the first coil 14 and the second coil 16. The control device 18 realizes the first discharge pattern shown in Figure 4(a) by discharging the first coil 14 twice at low rotation and low load as shown in Figure 6. The control device 18 realizes the third discharge pattern shown in Figure 5(a) by discharging the second coil 16 once at low rotation and high load. The control device 18 realizes the fourth discharge pattern shown in Figure 5(b) by discharging the first coil 14 once at high load. Note that the control device 18 can also realize the second discharge pattern by discharging the second coil 16 multiple times.

[0042] The control device 18 can realize the first to fourth discharge patterns by using the first coil 14 and the second coil 16 with different characteristics in this way.

[0043] Third Embodiment Next, a third embodiment will be described with reference to Figures 8 and 9. In the third embodiment, only the differences from the first and second embodiments will be described. In the third embodiment, an example will be described in which the vehicle C equipped with the pre-combustion engine 1 is a plug-in hybrid vehicle.

[0044] 8 , the control system 302 for the auxiliary combustion chamber internal combustion engine 301 includes the auxiliary combustion chamber internal combustion engine 301, a motor (FrM) 303, a generator (GEN) 304, a drive battery (BT) 306, a transaxle 308, an inverter 318 that controls the motor 303 and the generator 304, an accelerator pedal 316 operated by a user of the vehicle C, a charger 320 that can be connected to an external power source, a power supply device (external power supply device) 322 that can supply power to external devices such as home appliances, a vehicle control device (an example of a control device) 312, an engine control device (an example of a control device) 314 that controls the auxiliary combustion chamber internal combustion engine 301, and a fuel tank (FUEL TANK) 342. In addition, the vehicle C may include, for example, a charge button (not shown) that the user uses to instruct charging. Vehicle C of this embodiment is a plug-in hybrid electric vehicle (PHEV) equipped with external charging, which allows power from an external power source to be stored in drive battery 306 by charger 320, and external power feeding, which allows power from drive battery 306 to be supplied to external devices by power feeding device 322.

[0045] The pre-combustion chamber internal combustion engine 301 is connected to and drives a generator 304. Furthermore, in this embodiment, the pre-combustion chamber internal combustion engine 301 is capable of driving wheels C1 via a transaxle 308. The pre-combustion chamber internal combustion engine 301 of this embodiment is an in-line four-cylinder gasoline engine. The pre-combustion chamber internal combustion engine 301 receives fuel from a fuel tank 342 and burns and consumes the fuel. The configurations of the pre-combustion chamber internal combustion engine 301 and the control system 302 are the same as those of the first or second embodiment, and therefore description thereof will be omitted.

[0046] The motor 303 is connected to the wheels C1 via a transaxle 308 and an axle 310 and drives the wheels C1. In this embodiment, the motor 303 is a three-phase AC motor having multiple coils and multiple permanent magnets. The generator 304 is connected to the auxiliary combustion chamber internal combustion engine 301 and is capable of driving the auxiliary combustion chamber internal combustion engine 301. The generator 304 performs motoring to drive the auxiliary combustion chamber internal combustion engine 301 while the engine is being powered by electric power from the drive battery 306. Meanwhile, the generator 304 is driven by the auxiliary combustion chamber internal combustion engine 301 to generate electricity while the auxiliary combustion chamber internal combustion engine 301 is in operation. Therefore, the generator 304 is a motor-generator capable of both power running and generating electricity.

[0047] The driving battery 306 outputs electric power to the motor 303 and the generator 304, and also receives electric power generated by the motor 303 and the generator 304. Furthermore, the driving battery 306 receives external electric power via a charger 320. In this embodiment, the driving battery 306 is made up of multiple lithium-ion batteries.

[0048] The transaxle 308 has a plurality of gears and a clutch 308a. The auxiliary combustion engine 301 is connected to the generator 304 and an axle 310 via the transaxle 308. When the clutch 308a is in a disengaged state, the transaxle 308 cuts off the power transmission between the auxiliary combustion engine 301 and the axle 310, and when the clutch 308a is in a engaged state, the power of the auxiliary combustion engine 301 is transmitted to the axle 310.

[0049] The inverter 318 converts the DC power supplied from the drive battery 306 into AC power and adjusts the power supplied to the motor 303, thereby controlling the power running torque of the motor 303. When the motor 303 regenerates electricity, the inverter 318 converts the AC power supplied from the motor 303 into DC power and adjusts the power supplied to the drive battery 306, thereby controlling the regenerative torque of the motor 303.

[0050] The vehicle control device 312 is electrically connected to the motor 303 and the generator 304 via the inverter 318, and controls the motor 303 and the generator 304. The vehicle control device 312 is actually an ECU (Electronic Control Unit) configured by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc. The vehicle control device 312 controls the vehicle C based on maps and programs stored in the memory.

[0051] The vehicle control device 312 of this embodiment is further electrically connected to an engine control device 314. The engine control device 314 is electrically connected to various devices included in the pre-combustion chamber internal combustion engine 301 and controls the pre-combustion chamber internal combustion engine 301. Note that the control of the pre-combustion chamber internal combustion engine 301 may be performed by the vehicle control device 312 in addition to the engine control device 314. The vehicle control device 312 may also be electrically connected to various other devices of the vehicle C and perform various controls.

[0052] The vehicle C of this embodiment has driving modes such as EV mode, series mode, and parallel mode. In EV mode, the vehicle C drives the motor 303 with power from the drive battery 306. In series mode, the vehicle C drives the generator 304 with the auxiliary combustion chamber internal combustion engine 301 and uses the power generated by the generator 304 to drive the motor 303. In parallel mode, the vehicle C engages the clutch 308a and uses the power of the auxiliary combustion chamber internal combustion engine 301 to drive the wheels C1 via the axle 310. The vehicle C may also have a charge mode. In charge mode, the vehicle C drives the generator 304 with the auxiliary combustion chamber internal combustion engine 301 and stores the power generated by the generator 304 in the drive battery 306. In vehicle C, the vehicle control device 312 switches between driving modes depending on the depression state of the accelerator pedal 316 and the operation state of the charge button, controls the motor 303 and the generator 304 via the inverter 318, and causes the engine control device 314 to control the pre-chamber internal combustion engine 301.

[0053] Furthermore, the vehicle C of this embodiment has an external power supply mode. In the external power supply mode, when the connector 320a is connected to an external device, the vehicle control device 312 supplies power from the drive battery 306 to the external device using the power supply device 322. When the state of charge (SOC) of the drive battery 306 falls below a predetermined state of charge SOCt during the external power supply mode, the vehicle control device 312 executes an engine power generation external power supply mode in which the vehicle control device 312 starts the auxiliary combustion engine 301 to drive the generator 304, and stores the power generated by the generator 304 in the drive battery 306 and supplies it to the external device.

[0054] Such a vehicle C repeatedly restarts the pre-combustion chamber internal combustion engine 301. For example, in the series mode, when the accelerator pedal 316 is released, the pre-combustion chamber internal combustion engine 301 stops, and when the accelerator pedal 316 is depressed again, the pre-combustion chamber internal combustion engine 301 restarts to drive the generator 304. Additionally, when the charging rate SOC decreases during charging or power supply, the pre-combustion chamber internal combustion engine 301 restarts to drive the generator 304.

[0055] Next, a control procedure executed by the engine control device 314 will be described with reference to Fig. 9. The engine control device 314 starts the control procedure when an ignition switch (not shown) is turned on.

[0056] In step S1, the engine control device 314 determines whether or not the pre-combustion chamber internal combustion engine 301 is restarting. If the engine control device 314 determines that the pre-combustion chamber internal combustion engine 301 is restarting (YES in step S1), the process proceeds to step S2. In step S2, the engine control device 314 executes the first discharge pattern.

[0057] Thus, when restarting, reliable starting of the pre-combustion chamber internal combustion engine 1 is required. For this reason, the engine control device 314 suppresses misfires by causing the spark plug 10 to discharge the peak current Ap multiple times using the first discharge pattern. As a result, the engine control device 314 can stably start the pre-combustion chamber internal combustion engine 1. After executing the process of step S2, the engine control device 314 proceeds to the process of step S3.

[0058] If the engine control device 314 determines in step S1 that the auxiliary combustion chamber type internal combustion engine 301 is not restarting (step S1 NO), the process proceeds to step S6. In step S6, the engine control device 314 enters the cold start mode, and the process proceeds to step S7. In step S7, the engine control device 314 executes the second discharge pattern.

[0059] In the cold start mode, the pre-chamber internal combustion engine 301 is in a cold state, so the ignition plug 10 (see FIG. 1) needs to be warmed up. The warming up of the ignition plug 10 is promoted by discharging the ignition plug 10 for a long period of time, as in the second discharge mode. After executing the process of step S7, the engine control device 314 proceeds to step S3.

[0060] In step S3, the engine control device 314 determines whether starting is complete. If the engine control device 314 determines that starting is complete (YES in step S3), the process proceeds to step S4. If the engine control device 314 determines that starting is not complete (NO in step S3), the process proceeds to step S1.

[0061] In step S4, the engine control device 314 determines whether the pre-chamber internal combustion engine 301 is in a low-speed, low-load operating state. If the engine control device 314 determines that the engine is in a low-speed, low-load operating state (YES in step S4), the engine control device 314 proceeds to step S5. In step S5, the engine control device 314 executes the first discharge pattern. After executing the process of step S5, the engine control device 314 proceeds to step S12.

[0062] In step S4, if the engine control device 314 determines that the engine is not operating at low speed and low load (step S4: NO), the engine control device 314 proceeds to step S8. In step S8, the engine control device 314 determines whether the pre-chamber internal combustion engine 301 is operating at high speed and low load. If the engine control device 314 determines that the engine is operating at high speed and low load (step S8: YES), the engine control device 314 proceeds to step S9. In step S9, the engine control device 314 executes the third discharge pattern. After executing step S9, the engine control device 314 proceeds to step S12.

[0063] If the engine control device 314 determines in step S8 that the engine is not operating at high speed and low load (NO in step S8), the engine control device 314 proceeds to step S10. In step S10, the engine control device 314 determines that the auxiliary combustion chamber type internal combustion engine 301 is operating at high load, and proceeds to step S11. In step S11, the engine control device 314 executes the fourth discharge pattern. After executing the process of step S11, the engine control device 314 proceeds to step S12.

[0064] In step S12, the engine control device 314 determines whether the pre-combustion chamber internal combustion engine 301 has stopped. If the engine control device 314 determines that the pre-combustion chamber internal combustion engine 301 has stopped (YES in step S12), the process proceeds to step S1. If the engine control device 314 determines that the pre-combustion chamber internal combustion engine 301 has not stopped (NO in step S12), the engine control device 314 proceeds to step S4.

[0065] As described above, according to the control system 2 for the pre-combustion chamber internal combustion engine 1 of the first and second embodiments of the present disclosure, stable ignition can be achieved by changing the discharge current and discharge time in accordance with the rotation speed and load of the pre-combustion chamber internal combustion engine 1. According to the control system 302 for the pre-combustion chamber internal combustion engine 301 of the third embodiment of the present disclosure, stable ignition can be achieved by discharging multiple times when the pre-combustion chamber internal combustion engine 301 starts. In other words, according to the present disclosure, it is possible to provide the control systems 2, 302 for the pre-combustion chamber internal combustion engines 1, 301 that can suppress misfires.

[0066] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple modifications described in this specification can be combined as needed.

[0067] (a) In the above first and second embodiments, the first period is the period from time t1 to time t2, and the second period is the period from time t1 to time t3. However, the present disclosure is not limited to this. The discharge period may be changed as appropriate as long as the second period is longer than the first period.

[0068] (b) In the third embodiment, the vehicle C is described as a plug-in hybrid vehicle, but the present disclosure is not limited to this. The vehicle C may be, for example, a hybrid vehicle or an idle-stop vehicle.

[0069] 1, 301: Pre-combustion chamber type internal combustion engine 2, 302: Control system 4: Main combustion chamber, 6: Pre-combustion chamber, 8: Connecting passage, 10: Spark plug 10a: Center electrode 12: Fuel injection valve, 14: First coil, 16: Second coil, 18: Control device 61: Pre-combustion chamber wall, 61a: Bottom 314: Engine control device (an example of a control device), 304: Generator An: Normal current, Ap: Peak current, C: Vehicle, Ec: Load

Claims

1. A control system for a sub-chamber type internal combustion engine having a main combustion chamber and a sub-combustion chamber provided with a wall separating the main combustion chamber, the control system comprising: an ignition device disposed in the sub-combustion chamber; and a control device for controlling the ignition device, wherein the ignition device can change the discharge time to a first time and a second time longer than the first time, and can change the discharge current to a first current and a second current higher than the first current, and the control device discharges for the second time when the sub-chamber type internal combustion engine is operating at a low load, and discharges with the second current for the first time when the sub-chamber type internal combustion engine is operating at a high load. Control system for a sub-chamber type internal combustion engine.

2. The control system for a sub-chamber type internal combustion engine according to claim 1, wherein when the sub-chamber type internal combustion engine is operating at a low speed and low load, the second time is implemented by discharging a plurality of times.

3. The control system for a sub-chamber type internal combustion engine according to claim 1, wherein when the sub-chamber type internal combustion engine is operating at a low speed and low load, it discharges with the second current, and when the sub-chamber type internal combustion engine is operating at a high speed and low load, it discharges with the first current.

4. The ignition device has a first coil and a second coil, the first coil generates the second current for the first time, and the second coil generates the first current for the second time. The control system for a sub-chamber type internal combustion engine according to any one of claims 1 to 3.

5. The second current is generated by discharging the first coil and the second coil simultaneously, and the second time of discharge is performed by discharging the first coil and the second coil alternately. The control system for a sub-chamber type internal combustion engine according to claim 4.

6. A control system for a sub-chamber type internal combustion engine having a main combustion chamber and a sub-combustion chamber provided with a wall separating the main combustion chamber, the control system comprising: an ignition device disposed in the sub-combustion chamber; and a control device for controlling the ignition device, wherein the ignition device can change the discharge time to a first time and a second time longer than the first time, and the control device discharges the ignition device a plurality of times with current to implement the second time when the sub-chamber type internal combustion engine starts. Control system for a sub-chamber type internal combustion engine.

7. The auxiliary chamber type internal combustion engine is mounted on a vehicle, the vehicle has a generator driven by the auxiliary chamber type internal combustion engine, and when the control device restarts the auxiliary chamber type internal combustion engine to drive the generator, the control device discharges the current a plurality of times. The control system for an auxiliary chamber type internal combustion engine according to claim 6.

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