Engine control devices and hybrid vehicles
The engine control system enhances cold-start performance in pre-chamber engines by increasing sub-chamber fuel supply and ignition energy, addressing vaporization issues and maintaining chamber heat for smoother starts.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- MITSUBISHI MOTORS CORP
- Filing Date
- 2023-03-24
- Publication Date
- 2026-07-22
AI Technical Summary
In cold-start conditions, pre-chamber type engines face poor starting performance due to fuel vaporization difficulties and deteriorating exhaust gas components, exacerbated by the ignition device's narrow space in the sub-chamber.
An engine control system that selects between non-cold and cold injection controls, increasing fuel supply to the sub-chamber during cold starts, and allows multiple injections and enhanced ignition energy during the latter half of the expansion stroke.
Improves engine starting performance by promoting fuel vaporization and maintaining heat in the combustion chamber, ensuring smoother cold starts and efficient warm-up.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an engine control device and a hybrid vehicle equipped with the engine control device.
Background Art
[0002] Conventionally, a lean combustion engine that burns an air-fuel mixture with a lower fuel ratio (excess air relative to fuel) than the stoichiometric air-fuel ratio has been proposed. In addition, in order to burn the lean air-fuel mixture better, a sub-chamber type engine having a main chamber and a sub-chamber as combustion chambers has been proposed. In the sub-chamber type engine, a communication passage is provided in a partition wall separating the main chamber and the sub-chamber, and the air-fuel mixture formed by the fuel injected into the main chamber is supplied into the sub-chamber through the communication passage and is ignited by a spark plug in the sub-chamber. When a flame is formed in the sub-chamber, the flame propagates into the main chamber through the communication passage to ignite the air-fuel mixture in the main chamber. As a result, operation at a leaner air-fuel ratio becomes possible, and fuel consumption is said to be improved (see, for example, Patent Document 1 and Patent Document 2). [[ID=1�]]
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, in a general engine, since fuel is difficult to vaporize when the engine is not warmed up (in a cold state), the starting performance of the engine is poor, and the components contained in the exhaust gas immediately after starting may deteriorate. In particular, in the case of a sub-chamber type engine, since the ignition device faces a narrow space in the sub-chamber, there is a problem that the engine starting performance deteriorates when the engine is in a cold state if fuel has not spread into the sub-chamber even though fuel is supplied to the main chamber.
[0005] Therefore, the objective of this invention is to make engine starting smoother when the engine is cold in a pre-chamber type engine. [Means for solving the problem]
[0006] To solve the above problems, this invention provides an engine comprising: a combustion chamber having a main chamber formed surrounded by the inner circumferential surface of a cylinder, the inner surface of a cylinder head, and the top surface of a piston; a sub-chamber separated from the main chamber by a partition wall and formed at the cylinder head end of the main chamber; a communication passage provided in the partition wall that connects the main chamber and the sub-chamber; an injection device that supplies fuel to the combustion chamber; and an ignition device that faces the sub-chamber and ignites the air-fuel mixture in the sub-chamber; and a control means for controlling the engine, wherein the control means can select between non-cold injection control, which supplies an amount of fuel from the injection device to the sub-chamber according to the required torque, and cold injection control, which increases the amount of fuel supplied to the sub-chamber compared to the non-cold injection control, and the control device for the engine selects the cold injection control when the engine is cold.
[0007] Furthermore, in the cold-state injection control described above, a configuration can be adopted in which fuel is injected into the sub-chamber multiple times per combustion cycle.
[0008] Furthermore, in the cold-state injection control described above, a configuration can be adopted in which fuel is injected into the sub-chamber during the latter half of the expansion stroke in one combustion cycle.
[0009] When fuel is injected during the latter half of the expansion stroke, a configuration can be adopted that increases the ignition energy per injection or performs multiple ignitions during one combustion cycle.
[0010] A hybrid vehicle can be adopted that incorporates an engine control device comprising each of these embodiments, a rotating electric machine that operates by electricity and is capable of motorizing the engine, and in which the cold-state injection control is performed while the engine is being motorized by the rotating electric machine.
[0011] In this hybrid vehicle, the driving force for propulsion is supplied by the engine and the rotating electric machine, and it has at least two driving modes: a series driving mode and a parallel driving mode. When the parallel driving mode is selected, the cold-start injection control can employ a configuration that increases the amount of fuel injected into the sub-chamber compared to the cold-start injection control when the series driving mode is selected, or a second control that increases the number of ignitions in one combustion cycle, or both of the first and second controls. [Effects of the Invention]
[0012] According to this invention, starting a pre-chamber type engine when it is cold can be made smoother. [Brief explanation of the drawing]
[0013] [Figure 1] This is a longitudinal cross-section of a pre-chamber engine. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3A] This is a longitudinal cross-sectional view showing the combustion state of a pre-chamber engine. [Figure 3B] This is a longitudinal cross-sectional view showing the combustion state of a pre-chamber engine. [Figure 3C] This is a longitudinal cross-sectional view showing the combustion state of a pre-chamber engine. [Figure 4] This is a longitudinal cross-sectional view showing the state in which fuel injection is being directed towards the sub-chamber during cold-state injection control. [Figure 5] This is a longitudinal cross-sectional view showing the state in which the flame propagates from the sub-chamber during cold-state injection control. [Figure 6] This is a schematic diagram showing an example of a vehicle according to this invention. [Modes for carrying out the invention]
[0014] Embodiments of the present invention will be described based on the drawings. This embodiment is a hybrid vehicle 60 (hereinafter simply referred to as vehicle 60), and the main parts of the engine 10 mounted on the vehicle 60 are shown in FIGS. 1 and 2.
[0015] The vehicle 60 includes a battery 50 mainly used as a power source for running, and two rotating electric machines 30 and 40 operated by electric power. One rotating electric machine 30 (hereinafter referred to as the first rotating electric machine 30) functions as a starter, and the engine 10 is started by the operation of the first rotating electric machine 30. The other rotating electric machine 40 (hereinafter referred to as the second rotating electric machine 40) is a motor that supplies driving force for running. Further, the first rotating electric machine 30 also functions as a generator that generates electric power by the driving force of the engine 10 (see FIG. 6).
[0016] The vehicle 60 is a hybrid vehicle in which three types of driving modes, namely an electric driving mode (EV mode), a series driving mode, and a parallel driving mode, are set. An electronic control unit (Electronic Control Unit) 20 provided in the vehicle 60 selects an optimal driving mode according to the state of the vehicle 60, the driving state, the driver's request, etc. at that time. According to the selected driving mode, the engine 10, the first rotating electric machine 30, the second rotating electric machine 40, etc. are controlled.
[0017] The first rotating electric machine 30 is an electric generator (motor - generator) having both a function as an electric motor (motor) and a function as a generator (generator). When starting the engine 10, the first rotating electric machine 30 functions as an electric motor for the starter. At this time, the electric power from the battery 50 or a separately mounted auxiliary battery is used. Also, when the engine 10 is operating, it exhibits a function of generating electric power by the driving force of the engine 10. The electric power generated by the first rotating electric machine 30 is supplied to the second rotating electric machine 40, the battery 50, etc. The rotating shaft of the first rotating electric machine 30 is connected to the crankshaft of the engine 10 via an endless member such as a belt or a gear. During the operation of the engine 10, the first rotating electric machine 30 is usually rotated along with the rotation of the crankshaft.
[0018] The second rotating electric machine 40 is provided as a driving source for the vehicle 60 to travel. The second rotating electric machine 40 is driven using the electric power stored in the battery 50 or the electric power generated by the first rotating electric machine 30. As shown in FIG. 6, the second rotating electric machine 40 may be arranged only one on the front side, or may be provided on each of the front side and the rear side, and the number of installations and the installation locations are various. Further, the second rotating electric machine 40 also functions mainly as a generator that generates regenerative electric power during coasting.
[0019] A control unit (not shown) including an inverter that converts a direct current and an alternating current is provided between the first rotating electric machine 30 and the second rotating electric machine 40 and the electronic control unit 20. The rotational speed of the first rotating electric machine 30 and the second rotating electric machine 40 during driving is controlled by the electronic control unit 20 via the inverter.
[0020] The engine 10 is a gasoline engine. The rotation of the crankshaft of the engine 10 is switched between a state where it is transmitted to the drive wheels via a torque converter, a continuously variable transmission, a clutch, a differential, etc. according to the driving mode, and a state where the transmission is interrupted.
[0021] The battery 50 is a high-voltage power source capable of storing (charging) the generated electric power by the first rotating electric machine 30 and the regenerative electric power by the second rotating electric machine 40, and discharging the stored electric power. The battery 50 is mainly used as a power source for supplying electric power for traveling. When the vehicle 60 is a plug-in hybrid car (PHEV vehicle), the battery 50 can be externally charged, for example, by charging from an external power source such as a household AC power source (normal charging) or a high-voltage DC power source (rapid charging).
[0022] Vehicle 60 is equipped with a steering wheel, brake pedal, and accelerator pedal, which are operated by the driver. The brake pedal is equipped with a brake sensor 23 that detects the force with which the driver presses the brake pedal. The accelerator pedal is equipped with an accelerator position sensor 24 that detects the amount with which the driver presses the accelerator pedal. Brake information detected by the brake sensor 23 and accelerator information detected by the accelerator position sensor 24 are sent to the electronic control unit 20. Vehicle 60 is also equipped with a vehicle speed sensor, which is mounted on the axle or the like, to detect the vehicle's speed. Vehicle speed information detected by the vehicle speed sensor is also sent to the electronic control unit 20.
[0023] The vehicle 60 is also equipped with an engine speed sensor for detecting the rotational speed of the engine 10, rotational speed sensors for detecting the rotational speeds of the first rotating electric machine 30 and the second rotating electric machine 40, a voltage sensor for detecting the cell voltage of the battery 50, and a current sensor for detecting the current of the battery 50. The vehicle 60 is also equipped with a water temperature sensor for detecting the temperature of the coolant in the engine 10 and an oil temperature sensor for detecting the temperature of the engine oil. Information from these sensors is also sent to the electronic control unit 20.
[0024] The electronic control unit 20 comprises an engine control unit (control means) 21 that primarily controls the engine 10, and a vehicle control unit 22 that controls the operation of the entire hybrid vehicle. The electronic control unit 20 is a collection of electronic control devices (computers) that control various devices of the vehicle 60. Inside, it contains interfaces, processors, memory, etc., which are connected to each other via a bus. Together with the engine 10 and the electronic control unit 20, it constitutes the engine control device. The contents of the control performed by the engine control unit 21 and the vehicle control unit 22 are stored in memory in advance, and new data is stored as the control progresses, and this data is used for subsequent control. The electronic control unit 20 selects and switches between various driving modes, such as electric driving mode (a mode in which the vehicle is driven solely by the driving force of the second rotating electric motor 40), series driving mode (a mode in which the vehicle is driven solely by the driving force of the second rotating electric motor 40, using the driving force of the engine 10 to operate the first rotating electric motor 30 and generate electricity, and then using the generated electricity to drive the vehicle), and parallel driving mode (a mode in which the vehicle 60 is driven by the driving force of the engine 10, and the driving force of the second rotating electric motor 40 is used to assist the driving of the vehicle 60 as needed), in response to signals based on various operations of the driver and the driving state at that time.
[0025] The engine 10 is a pre-chamber engine. Figures 1 and 2 show the main components of one cylinder 2 of the engine 10. Its configuration includes an intake passage (intake port) 5 that sends air into the combustion chamber C, an exhaust passage (exhaust port) 6 drawn out from the combustion chamber C, and an injection device 9 that supplies fuel to the combustion chamber C. The opening 5a of the intake passage 5 to the combustion chamber C is opened and closed by an intake valve 7. The opening 6a of the exhaust passage 6 to the combustion chamber C is opened and closed by an exhaust valve 8. In this embodiment, the injection device 9 includes both a direct injection fuel injection device 9a that directly injects fuel into the combustion chamber C and a port injection fuel injection device 9b that injects fuel into the intake passage 5. In the figures, only components and means directly related to this invention are shown, and other components are omitted from the illustration. The number of cylinders in the engine 10 can be freely set according to the specifications of the vehicle 60 and the engine 10, and may be, for example, 3 cylinders, 4 cylinders, or any other number of cylinders.
[0026] As shown in Figure 1, the combustion chamber C comprises a main chamber 1 formed by being surrounded by the inner circumferential surface 2a of the cylinder (cylinder block) 2, the inner surface (bottom surface) of the cylinder head 13, and the top surface 3a of the piston 3, and a sub-chamber 11 separated from the main chamber 1 and formed at the end of the main chamber 1 on the cylinder head 13 side. The combustion chamber C also comprises a partition wall 14 separating the main chamber 1 and the sub-chamber 11, and a connecting passage 12 consisting of a pore that penetrates the partition wall 14. The space of the main chamber 1 and the space of the sub-chamber 11 are connected by the connecting passage 12. The sub-chamber 11 is also provided with an ignition device 4 that ignites the fuel-air mixture inside the sub-chamber 11 by generating an electric spark.
[0027] To describe the operating state of engine 10, first, as shown in Figure 3A, air is introduced into the main chamber 1 from the intake passage 5, and a lean air-fuel mixture is formed in the main chamber 1 by the injection of fuel from the injector 9. As shown in Figure 3B, the lean air-fuel mixture is pushed from the main chamber 1 into the sub-chamber 11 during the compression stroke when the piston 3 rises. Here, as shown in Figure 3C, a spark is generated at the electrode 4a of the ignition device 4, igniting the air-fuel mixture introduced into the sub-chamber 11. The ignition of the air-fuel mixture in the sub-chamber 11 causes the flame to be injected towards the main chamber 1 through the connecting passage 12, becoming a high-speed jet flame. This jet flame promotes combustion even when the air-fuel mixture is lean (including when a large amount of exhaust gas is introduced).
[0028] The engine 10 of this embodiment is based on a lean mixture with a lower fuel ratio (leaner fuel mixture) than the stoichiometric air-fuel ratio (A / F = 14.7). The air-fuel ratio of this basic lean mixture is used as the initial value. The air-fuel ratio is an air / fuel ratio, which is a dimensionless quantity obtained by dividing the mass of air by the mass of fuel. The electronic control unit 20 has the function of estimating the air-fuel ratio in the sub-chamber 11 and the air-fuel ratio of the entire combustion chamber C, etc., based on information from sensors around the engine 10.
[0029] In this embodiment, under normal operating conditions, two fuel injections are performed during one combustion cycle. Specifically, a first injection is performed mainly to supply fuel to the main chamber 1, and a second injection is performed mainly to supply fuel to the sub-chamber 11. The first fuel injection is performed during the intake or exhaust stroke, and the second fuel injection is performed during the compression stroke. In this embodiment, the first injection is performed mainly by a port injection type fuel injector 9b, and the second injection is performed mainly by a direct injection type fuel injector 9a.
[0030] Here, as shown in Figure 3C, a spark is generated at the electrode 4a of the ignition device 4, igniting the air-fuel mixture introduced into the sub-chamber 11. The ignition of the air-fuel mixture in the sub-chamber 11 causes the combustion gases to be injected as a high-speed flame through the connecting passage 12 towards the main chamber 1. This high-speed flame promotes combustion even when the air-fuel mixture is lean (including when a large amount of exhaust gas is introduced). The combustion gases are discharged to the outside through the exhaust passage 6 drawn out from the combustion chamber C. The exhaust passage 6 leads to the exhaust pipe 15 that goes towards the rear of the vehicle, and the exhaust pipe 15 is equipped with an exhaust gas purification device 16 and a muffler 17 that purify harmful components in the exhaust gas (see Figure 7). Sensors for detecting the amount and ratio of various components contained in the exhaust gas and sensors for detecting the temperature of the exhaust gas purification device 16 (temperature sensors) are provided before and after the exhaust gas purification device 16 as needed. The information obtained from these sensors is sent to the electronic control unit 20.
[0031] In general, in hybrid vehicles, there are several instances where a control system, known as motoring, is implemented to rotate the crankshaft by introducing the driving force of a rotating electric machine to the engine 10, which is not operating and does not burn fuel.
[0032] One example of a motoring scenario is when, as part of the electric driving mode, the vehicle 60 starts operation, and the crankshaft is rotated by the driving force of a rotating electric machine (for example, a first rotating electric machine 30) relative to the non-operating engine 10, and the vehicle is driven by the driving force of that rotating electric machine. This driving state, which is one aspect of the electric driving mode, will be hereinafter referred to as the motoring driving mode.
[0033] Another example of motoring is the engine starting mode. For instance, in addition to the aforementioned motoring driving mode, when the vehicle 60 is running solely on the driving force of the rotating electric motor (e.g., the second rotating electric motor 40) and the crankshaft are disconnected, and the remaining charge of the battery 50 decreases, the engine 10, which is in a non-operating state, is about to be started (combusted). In this case, the driving force of the rotating electric motor (e.g., the first rotating electric motor 30) is introduced to the non-operating engine 10 to rotate the crankshaft and start the engine 10.
[0034] In other words, the engine start mode refers to the time when the engine 10 is started (operating) when it is stopped without combustion (in a non-operating state) during a transition from an electric driving mode including motoring mode to a series driving mode, or from an electric driving mode including motoring mode to a parallel driving mode, or when the engine 10 is started (operating) by turning on the ignition of a vehicle 60 that has been parked for a long time and has had the ignition off.
[0035] As mentioned above, in engine starting mode, when the engine 10 is not warmed up (cold state), the fuel does not vaporize easily, resulting in poor starting performance for the engine 10, and potentially worsening of the exhaust gas components immediately after starting. In particular, in the case of a pre-chamber type engine, since the ignition device 4 faces the narrow space inside the pre-chamber 11, when cold, even if fuel is supplied to the main chamber 1, if the fuel does not reach the pre-chamber 11, there is a problem that the starting performance of the engine 10 will deteriorate. Also, in motoring driving mode, the crankshaft continues to rotate idly without combustion during motoring, so there is a concern that the warmed-up engine 10 will cool down. If the engine 10 cools down, its starting performance may deteriorate afterward.
[0036] Therefore, the control means provided by the electronic control unit 20 allows selection between non-cold injection control, which supplies an amount of fuel from the injection device 9 to the sub-chamber 11 according to the required torque, and cold injection control, which increases the amount of fuel supplied to the sub-chamber 11 compared to the non-cold injection control, and cold injection control is selected when the engine 10 is cold.
[0037] Specifically, in the engine start mode, if the engine 10 is warm, a non-cold injection control corresponding to normal engine start is performed; if the engine 10 is cold, a cold injection control different from normal engine start is performed.
[0038] During normal engine starting, fuel is injected to distribute fuel throughout the entire combustion chamber C, including the main chamber 1. While fuel injection during normal engine starting is primarily performed by a port injection fuel injector 9b, this may be used in combination with fuel injection by a direct injection fuel injector 9a. In non-cold state injection control, a fuel supply to the sub-chamber 11 is provided according to the required torque. When the engine 10 is started, if the required torque is 0 due to the accelerator being released, the fuel supply to the sub-chamber 11 can also be set to 0.
[0039] In contrast, in cold-start injection control, even under the same condition of a required torque of 0, the amount of fuel supplied to the sub-chamber 11 is set to be greater than 0. That is, when starting the engine 10, the injector 9 directs fuel injection towards the sub-chamber 11, i.e., it is a control that supplies fuel to the sub-chamber 11. When fuel is injected into the sub-chamber 11, the fuel-air mixture ignites within the sub-chamber 11, and the flame propagates into the main chamber 1 (see Figure 5), so the inner wall of the combustion chamber C is heated. Therefore, even in a cold state, vaporization of the fuel in the combustion chamber C is promoted, and a good start can be expected. This effect can be expected by deliberately directing the fuel injection direction towards the sub-chamber 11 during cold starting. At this time, combustion in the main chamber 1 is not necessarily required.
[0040] This cold-start injection control is not only for the purpose of heating the inner wall of the combustion chamber C in the cold-start engine mode, but can also be used for the purpose of maintaining heat by deliberately causing combustion to occur only in the sub-chamber 11 during motoring mode (while motoring) or during fuel cut operation, which would normally stop the supply of fuel to the combustion chamber C (such as when coasting downhill with the accelerator released). In this case, combustion in the main chamber 1 is not necessarily required, so fuel injection should be directed at the sub-chamber 11 to supply fuel to it. In this case, since combustion occurs only in the sub-chamber 11, the torque generated by the engine 10 is about the same as at idle. Compared to non-cold-start injection control, cold-start injection control increases the amount of fuel supplied to the sub-chamber 11, and combustion occurs in a limited area within the sub-chamber 11, thus providing the warm-up and heat retention effects described above.
[0041] Here, the state in which fuel is injected into the sub-chamber 11 means that fuel is injected directed towards the sub-chamber 11. For example, as shown in Figure 4, this means not only the case where the fuel injection centerline X from the injection device 9 is directed directly towards the sub-chamber 11 (especially the connecting passage 12), but also the case where the sub-chamber 11 is located within that injection range Y. Furthermore, the state in which fuel is injected into the sub-chamber 11 also includes cases where the fuel injected from the injection device 9 along the injection centerline X hits the inner surface of the cylinder head 13, etc., and bounces back, resulting in it being directed indirectly towards the sub-chamber 11 (especially the connecting passage 12), as well as cases where the injection device 9 is located inside the sub-chamber 11 and fuel is injected directly into the sub-chamber 11.
[0042] In this cold-state injection control, it is sufficient that fuel is supplied to the sub-chamber 11, and combustion in the main chamber 1 is not required. Therefore, during cold-state injection control, fuel injection directed towards the sub-chamber 11 may be performed by the direct-injection fuel injector 9a, and fuel injection by the port-injection fuel injector 9b may be stopped.
[0043] Here, "cold state" of the engine 10 generally refers to a state in which the engine 10 is at or below the ambient temperature of the environment in which it is located. In actual vehicles, for example, the engine coolant temperature can be set to below a predetermined temperature (e.g., 40°C), or the engine oil temperature can be set to below a predetermined temperature (e.g., 60°C). When the engine 10 is recognized as being in a cold state, the electronic control unit 20 sets up a cold state flag and, based on that cold state flag, switches the subsequent control from normal to cold state.
[0044] Furthermore, during this cold-state injection control, the ignition device 4 can be controlled to perform ignition multiple times per combustion cycle. In this case, the fuel injection directed towards the sub-chamber 11 may also be performed the same number of times per combustion cycle in conjunction with these multiple ignitions. For example, it may be set to a total of three times per combustion cycle, with one ignition during the compression stroke and two during the expansion stroke. Performing multiple ignitions per combustion cycle can shorten the time required for warming up and also enhance the heat retention effect. Regarding multiple ignitions, examples include methods such as performing multiple ignitions using a single coil during one combustion cycle, or methods such as performing a re-discharge using another coil after one discharge during one combustion cycle to create multiple sparks (boost).
[0045] Furthermore, when controlling injection in a cold state, it is preferable to inject fuel directed towards the sub-chamber 11 during the latter half of the expansion stroke in one combustion cycle. In particular, it is desirable to do so towards the end of the expansion stroke, just before the exhaust valve 8 opens. This suppresses the flame propagating from the sub-chamber 11 from hitting the piston 3. As a result, the temperature of the gas exhausted from the combustion chamber C can be efficiently raised, enabling smooth warming or temperature maintenance of the main chamber 1 and the sub-chamber 11.
[0046] As described above, injecting fuel in the latter half of the expansion stroke tends to make the mixture in the sub-chamber 11 leaner. This is because fuel enters the sub-chamber 11 less easily during the expansion stroke than during the compression stroke. For this reason, increasing the ignition energy per ignition, or performing multiple ignitions during one combustion cycle, makes ignition more reliable and further enhances the warm-up or heat retention effect of the main chamber 1 and sub-chamber 11. When multiple ignitions are performed during one combustion cycle, the same number of fuel injections directed towards the sub-chamber 11 may also be performed per combustion cycle in conjunction with those multiple ignitions.
[0047] Conventionally, the ignition energy was constant regardless of the ignition timing (crank angle). However, by increasing the ignition energy per combustion cycle in the sub-chamber 11, the warm-up or heat retention effect can be further enhanced. However, if the ignition energy is constantly increased, it is possible that the ignition device 4 (spark plug) may melt or that the thermal efficiency of the engine 10 will decrease due to the increased use of electricity. For this reason, when increasing the ignition energy, it is necessary to limit the energy increase to the minimum necessary. One method for increasing the ignition energy per cycle is to shorten the discharge time in the ignition device 4 to create a state with a higher current value and promote ignition.
[0048] The ignition energy increase control sets the ignition energy C2 (referred to as the second ignition energy C2) after the start of control to be relatively larger than the ignition energy C1 (referred to as the first ignition energy C1) in the steady state before the start of control. Here, (Second ignition energy C2) = (First ignition energy C1) × α In this case, α > 1, and for example, the value of α can be set to the minimum necessary value according to the operating conditions, such as 1.1, 1.2, 1.3, 1.4, etc.
[0049] As mentioned above, cold-state injection control is performed during electric driving mode, that is, when switching from electric driving mode to series driving mode, or from electric driving mode to parallel driving mode. Furthermore, cold-state injection control is also performed when the ignition is turned on to start (operate) the engine 10 of a vehicle 60 that has been parked for a long time with the ignition off.
[0050] Here, in the cold-start injection control when the parallel driving mode is selected (when switching to the parallel driving mode), the first control can be used, which increases the amount of fuel injected into the sub-chamber 11 compared to the cold-start injection control when the series driving mode is selected (when switching to the series driving mode). When the parallel driving mode is selected, it is considered highly likely that the engine speed and engine torque will fluctuate immediately due to subsequent changes in driving conditions, etc. Therefore, in response to the expectation of such fluctuations, the amount of fuel injected is increased to promote early warm-up.
[0051] Furthermore, when the parallel driving mode is selected (when switching to the parallel driving mode), the cold-start injection control can be a second control that increases the number of ignitions per combustion cycle compared to the cold-start injection control when the series driving mode is selected (when switching to the series driving mode). For example, it can be set to 1 ignition per combustion cycle when the series driving mode is selected, and 3 ignitions per combustion cycle when the parallel driving mode is selected. In this way, it is possible to warm up the engine earlier in response to the changes in operating conditions that are expected to occur after the parallel driving mode is selected.
[0052] The first control and the second control may be adopted individually, or both may be adopted simultaneously. Such first and second control can be adopted when there are at least two types of driving modes: a series driving mode and a parallel driving mode.
[0053] In the above embodiment, the injection device 9 is configured to include both a direct injection fuel injector 9a and a port injection fuel injector 9b. However, the embodiment is not limited to this, and a configuration in which the injection device 9 is equipped only with a direct injection fuel injector 9a is also conceivable. In this case, the direct injection fuel injector 9a may be provided with two separate injectors: one that injects fuel toward the sub-chamber 11, and another that injects fuel toward the main chamber 1 without directing it toward the sub-chamber 11, i.e., toward the inner circumferential surface 2a of the cylinder 2 or the top surface 3a of the piston 3 in the main chamber 1. Furthermore, a single injector 9 may be configured to switch its injection direction, for example, by injecting fuel toward the sub-chamber 11 during cold-state injection control, and by injecting fuel toward the main chamber 1 in other cases.
[0054] Furthermore, in the above description of the embodiment, a plug-in hybrid vehicle equipped with at least three driving modes—electric driving mode, series driving mode, and parallel driving mode—was assumed as the vehicle 60. However, this invention can also be applied to other types of hybrid vehicles, such as mild hybrid vehicles, and to general engine-powered vehicles other than hybrid vehicles. [Explanation of symbols]
[0055] 1 Main room 2 liters 3 pistons 4 Ignition device 9 Injection device 9a direct fuel injection system 9b Port injection fuel injection system 10 Engines 11 Antechamber 12 Communication path 20 Electronic control unit 50 batteries 60 Hybrid Vehicles (Vehicles) C Combustion chamber
Claims
1. An engine comprising: a combustion chamber having a main chamber formed by being surrounded by the inner circumferential surface of the cylinder, the inner surface of the cylinder head, and the top surface of the piston; a sub-chamber separated from the main chamber by a partition wall and formed at the end of the main chamber on the cylinder head side; a communication passage provided in the partition wall that connects the main chamber and the sub-chamber; an injection device that supplies fuel to the combustion chamber; and an ignition device that faces the sub-chamber and ignites the air-fuel mixture in the sub-chamber; and control means for controlling the engine, The control means can select between non-cold injection control, which supplies an amount of fuel from the injection device to the sub-chamber according to the required torque, and cold injection control, which increases the amount of fuel supplied to the sub-chamber compared to the non-cold injection control, and selects the cold injection control when the engine is cold. The cold-state injection control is initiated when the engine is rotating without combustion, and is an engine control device that rotates the engine by an external force while increasing the amount of fuel supplied to the sub-chamber to more than zero.
2. The control device for an engine according to claim 1, wherein in the cold-state injection control, fuel is injected into the sub-chamber multiple times per combustion cycle.
3. The control device for an engine according to claim 1, wherein in the cold-state injection control, fuel is injected into the sub-chamber during the latter half of the expansion stroke in one combustion cycle.
4. The control device for an engine according to claim 3, wherein when fuel is injected in the latter half of the expansion stroke, the ignition energy per injection is increased or multiple ignitions are performed during one combustion cycle.
5. The engine control device according to any one of claims 1 to 4 is mounted, and the engine is equipped with a rotating electric machine that operates by electric power and is capable of motorizing the engine, The cold-start injection control is performed in a hybrid vehicle while the engine is being motored by the rotating electric machine.
6. The engine control device according to any one of claims 1 to 4 is mounted, and a rotating electric machine is provided which is powered by electricity and capable of motorizing the engine, wherein the cold-state injection control is performed when the engine is being motorized by the rotating electric machine, The driving force for propulsion is supplied by the engine and the rotating electric machine, and the vehicle has at least two driving modes: a series driving mode and a parallel driving mode, and in the cold-start injection control when the parallel driving mode is selected, a first control is performed to increase the amount of fuel injected into the sub-chamber compared to the cold-start injection control when the series driving mode is selected, or a second control is performed to increase the number of ignitions in one combustion cycle, or both the first and second control are performed.