Engine control device

Abstract

To improve startability of an engine regardless of a state of a lock pin in a variable valve train in an engine control device.SOLUTION: An engine control device 30 is applied to an electric vehicle including an engine 1 provided with a hydraulic variable valve mechanism 10 having a lock pin, a traveling motor 2, and a secondary battery 5, and includes a setting part 31 and a control part 32. When the engine 1 is stopped, the setting unit 31 sets the flag to ON if the oil temperature of the engine oil that drives the variable valve mechanism 10 is equal to or lower than a predetermined temperature. The controller 32 can perform the passive scavenging control when the flag is on in the EV mode in which the vehicle travels by the driving force of the traveling motor 2 while the engine 1 is stopped. The passive scavenging control is control in which the throttle opening degree is fully opened and the inside of the combustion chamber is scavenged by the traveling wind during the EV mode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine control device for an electric vehicle equipped with an engine equipped with a hydraulic variable valve mechanism having a lock pin. [Background technology]

[0002] Some hydraulic variable valve timing systems (VVTs) are provided with a lock pin to fix the relative rotational phase of the vanes relative to the housing. In engines equipped with this type of variable valve timing system, a control method is known to resolve the deterioration of startability resulting from improper fitting of the lock pin. For example, a known technique is to suppress a sudden change in the relative phase by controlling a hydraulic oil supply / discharge mechanism that drives the vanes when the relative phase of the vanes is not in the locked phase during engine start-up (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-124619 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, when the lock pin is not properly engaged, the engine may stall with a large valve overlap between the intake and exhaust valves. In this case, some of the exhaust gas remaining in the exhaust pipe may flow back into the combustion chamber, entering the intake port or even the intake passage further upstream. The backflowing exhaust gas changes the air-fuel ratio in the combustion chamber when the engine is subsequently started, preventing a smooth start.

[0005] One of the objects of the present invention, which was devised in light of the above-mentioned problems, is to provide an engine control device that can improve engine startability regardless of the state of the lock pin in the variable valve mechanism. In addition to this object, another object of the present invention is to achieve effects derived from the configurations shown in the "Mode for Carrying Out the Invention" below, which are effects that cannot be obtained with conventional technologies. [Means for solving the problem]

[0006] The disclosed engine control device can be realized as the following disclosed aspects (application examples), which solve at least part of the above-mentioned problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected additionally as appropriate, and each of the aspects can be omitted. None of the aspects from aspect 2 onwards discloses an aspect or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed engine control device is an engine control device for an electric vehicle equipped with an engine provided with a hydraulic variable valve mechanism having a lock pin, a traction motor, and a secondary battery. The engine control device includes a setting unit that sets a flag to ON if the temperature of engine oil that drives the variable valve mechanism is equal to or lower than a predetermined temperature when the engine is stopped, and a control unit that can implement passive scavenging control when the flag is ON in an EV mode in which the vehicle travels using the driving force of the traction motor while the engine is stopped.

[0008] The passive scavenging control is a control in which the throttle is fully opened and the combustion chamber is scavenged with the wind generated when the engine is running in the EV mode. The predetermined temperature is preferably a temperature corresponding to the boundary between a low temperature range in which a fitting failure of the lock pin may occur when the engine is stopped and a normal temperature range in which the fitting failure does not occur.

[0009] Aspect 2. In relation to the aspect including Aspect 1 above, it is preferable that the control unit executes the passive scavenging control when the flag is on and the charging rate of the secondary battery exceeds a predetermined charging rate. Aspect 3. In relation to the aspects including Aspect 2 above, it is preferable that the control unit, in the EV mode, performs active scavenging control when the flag is on and the charging rate of the secondary battery is equal to or lower than the predetermined charging rate. Here, the active scavenging control is control for scavenging the combustion chamber by cranking without performing fuel injection or ignition.

[0010] Aspect 4. With respect to an aspect including the aspect 3 described above, it is preferable that the active scavenging control has a first control that generates negative pressure in the combustion chamber by cranking with the throttle fully closed, and a second control that promotes the introduction of fresh air into the combustion chamber by cranking with the throttle fully opened after the first control.

[0011] Aspect 5. In the aspects including Aspect 1 described above, it is preferable that the control unit performs active scavenging control when receiving an instruction to start the engine while the passive scavenging control is being performed. Here, the active scavenging control is a control for scavenging the inside of the combustion chamber by cranking without performing fuel injection or ignition.

[0012] Aspect 6. With respect to aspects including Aspect 5 above, it is preferable that the active scavenging control has a first control that generates negative pressure in the combustion chamber by cranking with the throttle fully closed, and a second control that promotes the introduction of fresh air into the combustion chamber by cranking with the throttle fully opened after the first control.

[0013] Aspect 7. With respect to an aspect including the aspect 1 described above (for example, an aspect described in any one of Aspects 1 to 6), it is preferable that the conditions for completing the passive scavenging control include that an estimated value of the amount of fresh air introduced into the combustion chamber exceeds a predetermined value, or that an instantaneous value of the intake air flow rate exceeds a predetermined flow rate, or that an implementation time of the passive scavenging control exceeds a predetermined passive scavenging time, or that a traveling distance while the passive scavenging control is being implemented exceeds a predetermined distance. [Effects of the Invention]

[0014] According to the disclosed engine control device, even if exhaust gas backflow occurs due to improper fitting of the lock pin when the engine is stopped, the exhaust gas can be discharged into the exhaust passage by utilizing the wind generated by EV driving while the engine is stopped. Therefore, the startability of the engine can be improved regardless of the state of the lock pin in the variable valve mechanism. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an engine and an engine control device. [Figure 2] 4 is a table showing control details of the engine control device. [Figure 3] 10 is a flowchart relating to flag setting when stopping the engine. [Figure 4] 4 is a flowchart relating to control after the engine is stopped. [Figure 5] 4 is a flowchart relating to control when starting the engine. [Figure 6] This is a graph showing the time-dependent fluctuations in passive scavenging control, where (A) is engine speed, (B) is throttle opening, (C) is vehicle speed, (D) is the estimated amount of fresh air introduced into the combustion chamber, (E) is intake flow rate, and (F) is mileage. [Figure 7] This is a graph showing the time-dependent fluctuations in active scavenging control and normal control, where (A) is the engine speed, (B) is the throttle opening, (C) is the intake manifold pressure, and (D) is the estimated amount of fresh air introduced into the combustion chamber. [Figure 8] This is a graph of the fluctuation over time when active scavenging control is performed during passive scavenging control. (A) shows the engine speed, (B) shows the throttle opening, (C) shows the vehicle speed, (D) shows the intake manifold pressure, and (E) shows the estimated amount of fresh air introduced into the combustion chamber. DETAILED DESCRIPTION OF THE INVENTION

[0016] The disclosed engine control device is applied to an electric vehicle equipped with an engine (internal combustion engine), a traction motor, and a secondary battery. The engine and the traction motor are the driving sources of the electric vehicle. The traction motor is driven by at least the electric power stored in the secondary battery. The engine is also provided with a hydraulic variable valve mechanism having a lock pin. The variable valve mechanism is a mechanism for changing the opening and closing timing of the intake and exhaust valves of the engine. The opening and closing timing of the intake and exhaust valves can be changed, for example, by changing the relationship (relative phase) between the rotational angle of the camshaft and the rotational angle of the housing that supports the camshaft.

[0017] A vane shaped like a blade is fixed to the end of the camshaft. The vane is housed in a hollow cylindrical housing. The housing is set up to rotate at half the angular speed of the crankshaft. Two chambers are formed inside the housing, each defined by the vane. These two chambers are called the advance chamber and the retard chamber. The relative phase of the vane with respect to the housing (i.e., the relative phase of the camshaft) is changed by generating an oil pressure difference between the advance chamber and the retard chamber, causing the vane to rotate. The oil pressure difference can be generated by adjusting the flow rate of engine oil (hydraulic fluid) filled in each of the advance chamber and the retard chamber.

[0018] The lock pin is a shaft-shaped member used to fix the relative phase of the camshafts. The lock pin is housed, for example, together with a spring, inside an axial hole drilled in the vane and is provided so as to be slidable in the axial direction. A recess into which the end of the lock pin can be fitted is provided in a position of the housing facing the axial hole of the vane. The relative phase of the camshafts is mechanically fixed by sliding the lock pin along the axial hole and fitting it into the recess.

[0019] The state in which the lock pin and the recess are engaged is called the "locked state," and the state in which they are disengaged is called the "unlocked state." The spring force of the lock pin is set so that it is in the locked state when the engine is stopped (when the oil pressure in the advance and retard chambers is low) and is in the unlocked state when the oil pressure in the advance and retard chambers rises. Note that the relative phase of the camshafts in the locked state corresponds to a state in which the valve overlap of the intake and exhaust valves is relatively small.

[0020] The inventors of this invention discovered that when the engine oil temperature is relatively low when the engine is stopped, the lock pin may fail to fit due to an imbalance in the oil pressure in each chamber and the spring force. When this failure occurs, the relative phase of the camshafts may fluctuate randomly, resulting in a large valve overlap between the intake and exhaust valves. This may cause some of the exhaust gas remaining in the exhaust pipe to gradually flow back into the combustion chamber while the engine is stopped, and then into the intake port or intake passage.

[0021] The backflowing exhaust gas can change the air-fuel ratio and oxygen concentration in the combustion chamber when the engine is subsequently started, potentially impairing engine startability. Therefore, the inventors of the present invention have devised a method for improving engine startability by scavenging the combustion chamber in advance, taking into account the possibility of exhaust gas backflow. On the other hand, if the engine oil temperature is sufficiently high when the engine is stopped, there is a high possibility that lock pin misfit will not occur. Therefore, the need for scavenging is determined based on the engine oil temperature. An example of implementing this control is described in detail below. [Example]

[0022] [1. Electric vehicles] 1 is a diagram showing the configuration of an engine control device 30 according to an embodiment and the configuration of an engine 1 that is the object of its control. The engine control device 30 and the engine 1 are mounted on an electric vehicle that has at least a traction motor 2 and a secondary battery (high-voltage battery 5). The electric vehicle of this embodiment is provided with the traction motor 2, a generator 3, a clutch 4, a high-voltage battery 5, a starter 6, and a low-voltage battery 7.

[0023] Electric vehicles in which the engine control device 30 and the engine 1 can be installed include HEVs (Hybrid Electric Vehicles) and PHEVs (Plug-in Hybrid Electric Vehicles). A PHEV is a hybrid electric vehicle that allows external charging of a secondary battery (high-voltage battery 5) that serves as a power supply source for the traction motor 2, or external power supply from the high-voltage battery 5 to various electrical appliances. A PHEV is provided with at least either a charging port (inlet) for inserting a charging cable that supplies power from external charging equipment, or an outlet (outlet) for external power supply.

[0024] The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 1 is equipped with a hydraulic variable valve mechanism 10 having at least a lock pin. The engine 1 is provided with an injector 8 for injecting fuel and a spark plug 9 for igniting the fuel. However, if the engine 1 is a diesel engine, the spark plug 9 may be omitted. Although FIG. 1 shows only one cylinder of the engine 1, the engine 1 may have multiple cylinders.

[0025] The traction motor 2 is a device that serves as a drive source for the electric vehicle together with the engine 1. The traction motor 2 has the function of propelling the electric vehicle using battery power stored in the high-voltage battery 5 and power generated by the generator 3, and the function of charging the high-voltage battery 5 with power generated by regeneration. A speed change mechanism (not shown) may be installed on the power transmission path connecting the traction motor 2 and the drive wheels.

[0026] The generator 3 has both the function of starting (cranking) the engine 1 using battery power stored in the high-voltage battery 5 and the function of generating electricity using the driving force of the engine 1. The high-voltage battery 5 is a secondary battery, such as a lithium-ion secondary battery, for supplying high-voltage power (for example, power of several hundred volts or more) to drive the electric vehicle. The high-voltage battery 5 is connected to the traction motor 2 and the generator 3 via a converter and inverter (not shown).

[0027] The clutch 4 is disposed on the power transmission path connecting the engine 1 and the drive wheels. When the clutch 4 is disengaged (released), the engine 1 and generator 3 are disconnected from the drive wheels, and the traction motor 2 is connected to the drive wheels. Therefore, for example, by operating only the traction motor 2, an EV mode (a mode corresponding to a state in which the electric vehicle can run on its own motor (EV running) among the multiple driving modes available to the electric vehicle) is realized. In addition, by operating the engine 1 and causing the generator 3 to generate electricity, a series mode (a mode corresponding to a state in which the energy transmission path is in series in the order of engine 1, generator 3, traction motor 2, and drive wheels) is realized.

[0028] On the other hand, when the clutch 4 is engaged (connected), the engine 1, the traction motor 2, and the generator 3 are all connected to the drive wheels. Therefore, for example, by operating only the engine 1, a so-called ENG mode (a mode in which the vehicle can be driven solely by the engine) is realized. In addition, by driving the traction motor 2 and the generator 3, a parallel mode (a mode in which the engine 1, the generator 3, and the traction motor 2 are connected in parallel to the drive wheels) is realized.

[0029] The series mode and parallel mode are also called HV mode (hybrid mode). Note that some of the driving modes, such as the EV mode, ENG mode, series mode, and parallel mode, may be omitted as appropriate.

[0030] The starter 6 is a device for starting (cranking) the engine 1 using battery power stored in a low-voltage battery 7. The starter 6 is also called a cell motor or starter motor, and if it also has a power generation mechanism, it is also called a starter dynamo. The low-voltage battery 7 is a secondary battery, such as a lead-acid battery, for supplying low-voltage power (for example, power of several tens of volts at most) to drive various electrical components.

[0031] The intake system of the engine 1 is provided with an intake passage 11, a throttle valve 12, and an intake manifold 13, while the exhaust system is provided with an exhaust passage 14 and an exhaust manifold 15. An EGR passage 16 is provided between the intake passage 11 and the exhaust passage 14 to recirculate a portion of the exhaust gas. An EGR valve 17 is installed in the EGR passage 16. The connection position of the EGR passage 16 with respect to the intake passage 11 and the exhaust passage 14 can be changed as appropriate.

[0032] The engine 1 is provided with sensors for detecting information related to the operating state of the engine 1. The oil temperature sensor 20 detects the temperature of the engine oil that drives the variable valve mechanism 10. The oil temperature may be detected near the variable valve mechanism 10 or at another location (for example, inside the oil pan). The engine rotation speed sensor 21 detects the engine rotation speed (number of engine rotations per unit time).

[0033] The intake manifold pressure sensor 22 detects the intake manifold pressure (pressure inside the intake manifold). The outside air temperature sensor 23 detects the outside air temperature (temperature of the outside air and the air passing through the intake passage 11). The air flow sensor 24 detects the intake air flow rate (flow rate of air passing through the throttle valve 12). The oxygen concentration sensor 25 detects the oxygen concentration in the exhaust passage 14. Information detected by these sensors is transmitted to the engine control device 30, which will be described later.

[0034] The electric vehicle is provided with sensors for detecting information related to the running state of the electric vehicle and the driver's operation state. An accelerator pedal stroke sensor 26 detects the accelerator pedal depression stroke (accelerator opening). A brake pedal stroke sensor 27 detects the brake pedal depression stroke. A vehicle speed sensor 28 detects the vehicle speed (travel speed of the electric vehicle). Information detected by these sensors is transmitted to an engine control device 30, which will be described later.

[0035] [2. Engine control device] The engine control device 30 is a computer (electronic control unit, ECU) that controls the operating state of the engine 1. The engine control device 30 has a built-in processor (arithmetic processing unit) and memory (storage device). The contents of the control (control program) performed by the engine control device 30 are stored in the memory and executed by the processor. The engine control device 30 may be provided as a single device or may be provided as separate devices.

[0036] The engine control device 30 obtains information obtained from various sensors as well as information from the high-voltage battery 5 and the low-voltage battery 7 (e.g., their respective state of charge (SOC), voltage values, current values, and internal resistance values), and controls the operating states of various devices based on this information to control the operating state of the engine 1. Specific examples of the various devices include the generator 3, starter 6, injector 8, spark plug 9, throttle valve 12 (throttle opening), and EGR valve 17 (EGR opening).

[0037] As shown in Fig. 1, the engine control device 30 includes a setting unit 31 and a control unit 32. These elements are shown by classifying the functions of the engine control device 30 for convenience. These elements can be written as independent programs, or can be written as a composite program that combines multiple elements. These elements can be integrated and implemented in a single engine control device 30, or can be distributed and implemented in multiple engine control devices 30.

[0038] The setting unit 31 has a function of setting a control flag based on the engine oil temperature when the engine 1 that has been operating is stopped. The setting unit 31 sets the flag to on (F=1) when the oil temperature is equal to or lower than a predetermined temperature, and sets the flag to off (F=0) when the oil temperature exceeds the predetermined temperature. The predetermined temperature is preferably a temperature corresponding to the boundary between a low temperature range in which a lock pin may fail to fit when the engine 1 is stopped and a normal temperature range in which a lock pin will not fail to fit. Specifically, the predetermined temperature is, for example, a temperature within a range of 0 to 50°C.

[0039] The control unit 32 controls the operating state (start, stop) and scavenging of the engine 1. The control unit 32 has the function of performing normal control, passive scavenging control, and active scavenging control. The normal control is control for starting the engine 1, and the passive scavenging control and active scavenging control are controls for scavenging the engine 1. The passive scavenging control is control for passively scavenging using the wind generated while the engine is running, and the active scavenging control is control for actively scavenging by cranking.

[0040] [2-1] Normal control Normal control is a control for starting the stopped engine 1 by cranking while performing both fuel injection by the injector 8 and ignition by the spark plug 9. Normal control is initiated when predetermined engine start conditions are met. The device for cranking the engine 1 under normal control is the generator 3 or the starter 6, and either may be used.

[0041] The engine start conditions determined by the control unit 32 can be various well-known conditions such as those shown below. The control unit 32 can determine that the engine start conditions are met when, for example, at least one of the following is met. However, the engine start conditions are not limited to these. The following predetermined charging rate is preferably set as a threshold value at which the generator 3 should be driven by the engine 1 to charge the high-voltage battery 5. The predetermined charging rate can be set appropriately within the range of, for example, 10 to 40%. Furthermore, an accelerator operation in which the accelerator opening exceeds a predetermined opening in EV mode is defined as an "engine start start command by the driver."

[0042] - Idling stop control has been cancelled. (The brake pedal is released or the accelerator pedal is depressed.) In EV mode, the charging rate of the high-voltage battery 5 is below a predetermined charging rate. - In EV mode, the vehicle speed exceeds the specified speed. - In EV mode, the accelerator opening exceeds the specified opening.

[0043] Various known conditions such as those shown below can be applied as engine stop conditions. However, the engine stop conditions are not limited to these. The engine stop conditions may be determined by the control unit 32, or by another control device (not shown). The control and processing for stopping the engine 1 may be the responsibility of the control unit 32, or may be the responsibility of another control device (not shown).

[0044] - Idling stop control has been initiated. (The brake pedal was pressed continuously while the vehicle speed was 0.) In HV mode, the charging rate of the high-voltage battery 5 exceeds a predetermined charging rate. In HV mode, the vehicle speed is below a specified speed. In HV mode, the accelerator opening is below the specified opening.

[0045] [2-2] Passive scavenging control Passive scavenging control is a control in which the throttle is fully opened and the inside of the combustion chamber is passively scavenged by the wind generated when the engine is in EV mode. Passive scavenging control is initiated when the engine start condition is not met. Passive scavenging control is executable when a flag is on (F=1) in EV mode. Passive scavenging control may be executed based only on the flag condition, or may be executed after taking into consideration conditions other than the flag. In other words, the start condition for passive scavenging control includes at least the flag being on (F=1) in EV mode, and may include other additional conditions.

[0046] Specific examples of additional conditions are shown below. The control unit 32 can determine that the conditions for starting passive scavenging control are met when one of the following additional conditions (or multiple conditions) is met in addition to the fact that "the flag is on (F=1) in the EV mode." The charging rate of the high-voltage battery 5 exceeds the specified charging rate. The vehicle speed exceeds the specified speed. The throttle opening is greater than the specified opening.

[0047] The additional conditions may overlap with part of the engine start conditions. The additional conditions may be completely the same as part of the engine start conditions, or may include part of the engine start conditions. The necessary conditions for passive scavenging control preferably include the engine start conditions not being satisfied. When the flag is on (F=1) in the EV mode and the engine start conditions are satisfied, it is preferable that active scavenging control is immediately performed instead of passive scavenging control.

[0048] In passive scavenging control, fuel injection by the injector 8 and ignition by the spark plug 9 are not performed, and the engine 1 is not cranked. However, when the electric vehicle runs with the throttle fully open, wind from the vehicle's running is introduced into the intake passage 11. As a result, even if exhaust gas flows back into the combustion chamber or the intake passage 11, the exhaust gas is expelled into the exhaust passage 14. Therefore, compared to when passive scavenging control is not performed, the startability of the engine 1 is improved when normal control is subsequently performed.

[0049] The passive scavenging control continues unless a predetermined passive scavenging completion condition (a completion condition of the passive scavenging control) is satisfied. After that, when the passive scavenging completion condition is satisfied, the passive scavenging control ends. If the engine start condition is satisfied before the passive scavenging completion condition is satisfied, the active scavenging control starts. Specific examples of the passive scavenging completion conditions are as follows: The control unit 32 can determine that the passive scavenging completion conditions are met when, for example, at least one of the following is met.

[0050] The estimated amount of fresh air introduced into the combustion chamber exceeded a specified value. The instantaneous intake flow rate exceeded the specified flow rate. The passive scavenging control execution time has exceeded the specified passive scavenging time. The driving distance while passive scavenging control is in operation exceeds the specified distance. The exhaust gas in the exhaust passage 14 can be considered to have been purged. (The oxygen concentration in the exhaust passage 14 has reached a concentration equivalent to that of the outside air.)

[0051] The estimated value of the fresh air volume can be calculated based on the intake air flow rate (instantaneous value, integrated value) detected by the air flow sensor 24 and the vehicle running speed. The estimated value of the fresh air volume increases as the air density increases, and therefore may be increased as the outside air temperature detected by the outside air temperature sensor 23 decreases. Similarly, the predetermined passive scavenging time may be decreased as the outside air temperature decreases.

[0052] [2-3] Active scavenging control Active scavenging control is a control that actively scavenges the combustion chamber by cranking the engine 1 without performing fuel injection by the injector 8 or ignition by the spark plug 9. Active scavenging control is performed prior to normal control, mainly when the engine start conditions are met.

[0053] When active scavenging control is started, normal control is started after active scavenging control ends. Even when an engine start condition is met while passive scavenging control is being performed (for example, when the driver issues an instruction to start the engine), active scavenging control is started, and normal control is started after active scavenging control ends. By performing active scavenging control, even if exhaust gas flows back into the combustion chamber or the intake passage 11, the exhaust gas is expelled into the exhaust passage 14. This improves the startability of the engine 1 during normal control, which is performed after active scavenging control. The device that cranks the engine 1 during active scavenging control is the generator 3 or the starter 6, and either may be used.

[0054] The active scavenging control of this embodiment includes two different controls, namely, a first control and a second control. The first control is a control that generates negative pressure in the combustion chamber by cranking with the throttle fully closed. The second control is a control that promotes the introduction of fresh air into the combustion chamber by cranking with the throttle fully opened after the first control. Even if only the second control is performed without performing the first control, it is possible to scavenge the combustion chamber.

[0055] On the other hand, by performing the first control before the second control, the negative pressure in the combustion chamber increases, and fresh air can be forcefully flowed into the combustion chamber during the second control. This improves the efficiency of scavenging, and exhaust gas scavenging can be completed in a short time. Note that the first control is not a required control and can be omitted. If the first control is omitted, the second control is immediately performed when a predetermined engine start condition is met.

[0056] The main flows of active scavenging control and normal control are as follows. First, when the conditions for implementing active scavenging control are met, the first control is started (implemented). The first control is continued unless a predetermined transition condition is met. After that, when the transition condition is met, the first control ends, and the second control is started (implemented). The second control is continued unless a predetermined active scavenging completion condition is met. After that, when the active scavenging completion condition is met, the second control ends, and normal control is started (implemented). The normal control is continued unless a predetermined engine start completion condition is met. After that, when the engine start completion condition is met, the normal control ends.

[0057] Specific examples of the transition condition are as follows: The control unit 32 can determine that the transition condition is met when, for example, at least one of the following is met. - The intake manifold pressure (pressure inside the combustion chamber) has fallen below a specified pressure. The duration of the first control exceeded the first predetermined time. - The engine speed due to cranking exceeds the specified speed.

[0058] Specific examples of the active scavenging completion condition are given below: The control unit 32 can determine that the active scavenging completion condition is met when, for example, at least one of the following is met. The active scavenging control execution time has exceeded the second predetermined time. (Or the execution time of the second control exceeds the second predetermined time.) The estimated amount of fresh air introduced into the combustion chamber exceeded a specified value. The exhaust gas in the exhaust passage 14 can be considered to have been purged. (The oxygen concentration in the exhaust passage 14 has reached a concentration equivalent to that of the outside air.)

[0059] The estimated value of the fresh air volume can be calculated based on the intake air flow rate (instantaneous value, integrated value) detected by the air flow sensor 24 and the engine rotation speed (instantaneous value, integrated value) due to cranking. The estimated value of the fresh air volume increases as the air density increases, and therefore may be corrected to be increased as the outside air temperature detected by the outside air temperature sensor 23 decreases. Similarly, the first predetermined time period and the second predetermined time period may be corrected to be shortened as the outside air temperature decreases. Furthermore, when the engine 1 is cold, frictional resistance increases, making it difficult to increase the engine rotation speed due to cranking. Therefore, the first predetermined time period and the second predetermined time period may be corrected to be extended as the outside air temperature, oil temperature, engine coolant temperature, etc. decrease.

[0060] The engine start completion conditions determined by the control unit 32 can be various known conditions such as those shown below. For example, the control unit 32 can determine that the engine start completion conditions are met when at least one of the following is met. However, the engine start completion conditions are not limited to these. The engine speed exceeds the specified self-sustaining speed. - The engine torque exceeds the specified self-sustaining torque. The normal control execution time has exceeded the third specified time.

[0061] FIG. 2 is a table showing the control contents of the engine control device 30. The purpose of passive scavenging control is to scavenge air using the wind generated by the electric vehicle traveling in EV mode. Therefore, during passive scavenging control, the throttle is fully opened and the EGR valve 17 is closed (fully closed state). Furthermore, neither fuel injection by the injector 8 nor ignition by the spark plug 9 is performed, and the engine 1 is not cranked.

[0062] In both active scavenging control and normal control, the engine 1 is cranked with the EGR valve 17 closed. The purpose of cranking during active scavenging control is to scavenge exhaust gas that is likely to have flowed back. Therefore, in active scavenging control, neither fuel injection by the injector 8 nor ignition by the spark plug 9 is performed. On the other hand, the purpose of cranking during normal control is to provide an impetus to start the engine 1 rotating independently. Therefore, in normal control, both fuel injection by the injector 8 and ignition by the spark plug 9 are performed.

[0063] Active scavenging control includes a first control that is performed first and a second control that is performed afterwards. The purpose of cranking during the first control is to increase the negative pressure in the combustion chamber. Therefore, during the first control, the throttle opening is fully closed. On the other hand, the purpose of cranking during the second control is to promote the introduction of fresh air into the combustion chamber by utilizing the intake inertia effect. Therefore, during the second control, the throttle opening is fully opened. During the subsequent normal control, the throttle opening is again fully closed to suppress excessive acceleration of the engine 1 (a sudden increase in engine speed immediately after starting).

[0064] In this embodiment, "fully closed" means that the throttle opening is sufficiently narrowed, and does not necessarily mean that the throttle opening is 0%. Similarly, "fully open" means that the throttle opening is sufficiently open, and does not necessarily mean that the throttle opening is 100%. "Fully open" during passive scavenging control may be read as "passive scavenging opening V0," "fully closed" during first control may be read as "first opening V1," "fully open" during second control may be read as "second opening V2," and "fully closed" during normal control may be read as "third opening V3."

[0065] It is preferable that the magnitude relationships of the various opening degrees described above satisfy the following relationships. 0≦V1 <V2≦100[%] 0≦V3 <V2≦100[%] 0≦V3 <V0≦100[%] 0≦V1 <V0≦100[%] V1 may be the same as V3, or may be different, and either may be larger. V0 may be the same as V2, or may be different, and either may be larger.

[0066] [3. Flowchart] [3-1] Flag setting 3 is a flowchart relating to flag setting when stopping the engine 1. The control shown in this flowchart is repeatedly executed by the engine control device 30 at predetermined intervals while the engine 1 is operating. In step A1, it is determined whether or not an engine stop condition is met in the control unit 32. If this condition is met, the process proceeds to step A2, and if not, the control for this cycle ends.

[0067] In step A2, the temperature of the engine oil that drives the variable valve mechanism 10 is detected. In the following step A3, it is determined whether the oil temperature is equal to or lower than a predetermined temperature. If the oil temperature is equal to or lower than the predetermined temperature, the process proceeds to step A4, where the value of flag F is set to F=1 in the setting unit 31 (i.e., the flag is on). F=1 means that if the engine 1 is stopped in this state, there is a high possibility that the lock pin will not fit properly and that exhaust gas will flow backward.

[0068] On the other hand, if the oil temperature exceeds the predetermined temperature, the process proceeds to step A5, where the setting unit 31 sets the value of flag F to F=0 (i.e., the flag is off). F=0 means that even if the engine 1 is stopped as it is, there is a high possibility that the lock pin will not malfunction and exhaust gas will not flow back. The value of flag F (flag state) set in steps A4 and A5 is stored in, for example, a non-volatile memory or a data storage device. In the following step A6, the control unit 32 performs a known engine stop process (for example, stopping fuel injection and ignition) and stops the engine 1. When the engine stop process is completed, the control shown in FIG. 4 is executed.

[0069] [3-2] Various controls 4 is a flowchart relating to control after stopping of the engine 1. The control shown in this flowchart is repeatedly executed in the engine control device 30 (mainly the control unit 32) at predetermined intervals while the engine 1 is stopped. In step B1, it is determined whether or not the flag set by the setting unit 31 is on (F=1). If this condition is met, the process proceeds to step B2, and if not, the process proceeds to step B16 (symbol A) in FIG. 5, since it is deemed that scavenging control itself is unnecessary.

[0070] In step B2, it is determined whether the driving mode is EV mode. If this condition is met, the process proceeds to step B3; if not, the process proceeds to step B15 (symbol B) in Figure 5. A specific example of when the driving mode is not EV mode is when idling stop control is initiated in parallel mode (when the electric vehicle stops temporarily at an intersection while traveling using the driving force of the engine 1 and the traction motor 2, and the engine 1 is stopped by idling stop control).

[0071] In step B3, it is determined whether the charging rate of the high-voltage battery 5 exceeds a predetermined charging rate. If this condition is met, the process proceeds to step B4, but if not, it is determined that the high-voltage battery 5 needs to be charged, and the process proceeds to step B8 (symbol C) in FIG. 5. In step B4, passive scavenging control is performed. In passive scavenging control, the throttle opening is controlled to be fully open, and the EGR valve 17 is controlled to be fully closed. Neither fuel injection by the injector 8 nor ignition by the spark plug 9 is performed, and cranking is also not performed. As a result, running wind is passively introduced into the intake passage 11, and exhaust gas in the combustion chamber and the intake passage 11 is scavenged.

[0072] In the next step B5, it is determined whether or not the engine start conditions are met. The engine start conditions include the driver issuing an engine start command. If the determination conditions of step B5 are met, it is determined that it is necessary to start the engine 1 and transition to HV mode, and the process proceeds to step B8 (symbol C) in FIG. 5. On the other hand, if this condition is not met, it is determined that there is no need to start the engine 1 (a state in which passive scavenging control can be continued in EV mode), and the process proceeds to step B6.

[0073] In step B6, it is determined whether or not the passive scavenging completion condition is satisfied. If the passive scavenging completion condition is not satisfied, the control returns to step B4, and the passive scavenging control continues. If the passive scavenging completion condition is satisfied, the value of flag F is set to F=0 in step B7, the throttle opening is fully closed, and the control for this cycle ends. In the next control cycle, scavenging has already been completed, so the process proceeds from step B1 to step B16 (symbol A) in FIG. 5.

[0074] In step B8 of FIG. 5, which follows the No route of step B3 and the Yes route (symbol C) of step B5, a first control of the active scavenging control is performed. In the first control, the throttle opening is controlled to be fully closed, and the EGR valve 17 is controlled to be fully closed. Neither fuel injection by the injector 8 nor ignition by the spark plug 9 is performed, and cranking by the generator 3 or the starter 6 is performed. This increases the negative pressure in the combustion chamber. In the following step B9, it is determined whether or not a transition condition from the first control to the second control is satisfied. If the transition condition is not satisfied, the control returns to step B8, and the first control continues. If the transition condition is satisfied, the control proceeds to step B10.

[0075] In step B10, the second control of the active scavenging control is performed. In the second control, the states of the EGR valve 17, the injector 8, and the spark plug 9 are the same as those in the first control. Meanwhile, the throttle opening is controlled to be fully open, and cranking is performed by the generator 3 or the starter 6. This promotes the introduction of fresh air into the combustion chamber. In the following step B11, it is determined whether or not the active scavenging completion condition is satisfied. If the active scavenging completion condition is not satisfied, the control returns to step B10, and the second control is continued. If the active scavenging completion condition is satisfied, the value of flag F is set to F=0 in step B12, and then the process proceeds to step B13.

[0076] In step B13, normal control is performed. If F=1 in step B1, passive scavenging control or active scavenging control is performed, so that F=0, and then normal control is performed. In normal control, the throttle opening is controlled to be fully closed, and the EGR valve 17 is controlled to be fully closed. Furthermore, fuel injection by the injector 8 and ignition by the spark plug 9 are both performed, and cranking by the generator 3 or the starter 6 is performed. This causes the engine 1 to start.

[0077] In the following step B14, it is determined whether or not the engine start completion condition is satisfied. If the engine start completion condition is not satisfied, the control returns to step B13, and normal control continues. If the engine start completion condition is satisfied, the control of this flowchart ends. After the engine 1 is started, the control shown in FIG. 3 is executed.

[0078] In step B15 of FIG. 5, which follows the No route (symbol B) of step B2, it is determined whether or not the engine start condition is satisfied, similar to step B5. If the condition of step B15 is satisfied, the process proceeds to step B8, where the first control of the active scavenging control is performed. If the condition of step B15 is not satisfied, the control for this cycle ends. In the next control cycle, the condition of step B15 is determined again via the Yes route of step B1 and the No route of step B2. The control flow after the first control is performed is as described above.

[0079] In step B16 of FIG. 5, which follows the No route (symbol A) of step B1, it is determined whether or not the engine start condition is satisfied, similar to step B5. If the condition of step B16 is satisfied, the process proceeds to step B13, where normal control is performed. If the condition of step B16 is not satisfied, the control for this cycle ends. In the next control cycle, the condition of step B16 is determined again via the No route of step B1. The control flow after normal control is performed is as described above.

[0080] [4. Time Chart] [4-1] Passive scavenging control FIG. 6 is a graph showing the time-dependent fluctuations in passive scavenging control, where (A) represents the engine speed, (B) represents the throttle opening, (C) represents the vehicle speed, (D) represents the estimated amount of fresh air introduced into the combustion chamber, (E) represents the intake air flow rate, and (F) represents the mileage.

[0081] When the engine 1 is stopped, the flag is set to on (F=1) at time t0, and the electric vehicle is running in EV mode (see Figures 6(A) and 6(C)). At this time, if the charge rate of the high-voltage battery 5 exceeds a predetermined charge rate, passive scavenging control is initiated. In passive scavenging control, fuel injection, ignition, and cranking are not performed. Meanwhile, the throttle opening is fully open (see Figures 6(A) and 6(B)). As a result, running wind is introduced into the intake passage 11, and the estimated fresh air volume gradually increases (see Figure 6(D)).

[0082] When the electric vehicle stops at time t1, scavenging by the traveling wind is temporarily stopped. When the electric vehicle starts moving at time t2, scavenging by the traveling wind is resumed (see Figures 6(C) and 6(D)). Passive scavenging control continues, for example, until a passive scavenging completion condition is met, after which the throttle opening is controlled to be fully closed. When the passive scavenging completion condition is met, scavenging of the intake passage 11 and the combustion chamber is considered to be completed, so there is no need to perform active scavenging control when the engine 1 is started thereafter.

[0083] The passive scavenging completion condition may be, for example, that the estimated amount of fresh air exceeds a predetermined value (see FIG. 6(D)), that the duration of passive scavenging control exceeds a predetermined passive scavenging time (time corresponding to t3-t0) (see FIG. 6(A)), that the instantaneous value of intake air flow rate exceeds a predetermined flow rate (see time t4 in FIG. 6(E)), or that the traveling distance while passive scavenging control is being performed exceeds a predetermined distance (see time t5 in FIG. 6(F)).

[0084] [4-2] Active scavenging control FIG. 7 is a graph showing the time-dependent fluctuations in active scavenging control and normal control, where (A) represents the engine speed, (B) represents the throttle opening, (C) represents the intake manifold pressure, and (D) represents the estimated amount of fresh air introduced into the combustion chamber.

[0085] When engine 1 is stopped, at time t 10 Assume that the flag is set to on (F=1) and the electric vehicle is running in EV mode (see FIG. 7(A)). At this time, if the charge rate of the high-voltage battery 5 is equal to or lower than a predetermined charge rate, the first control of the active scavenging control is initiated. In the first control, cranking is performed without fuel injection or ignition, with the throttle opening kept fully closed (see FIGS. 7(A) and (B)). As a result, the estimated fresh air amount gradually increases, and the intake manifold pressure gradually decreases (see FIGS. 7(C) and (D)).

[0086] time t 11 When the transition condition is satisfied, the first control ends and the second control starts. The transition condition may be, for example, that the intake manifold pressure becomes equal to or lower than a predetermined pressure (see FIG. 7C), or that the execution time of the first control is equal to or lower than a first predetermined time (t 11 -t 10 The second control may be performed by fully opening the throttle and cranking without fuel injection or ignition (see Figures 7(A) and 7(B)). This promotes the introduction of fresh air into the combustion chamber, and the estimated fresh air amount increases rapidly (see Figure 7(D)).

[0087] time t 12When the active scavenging completion condition is satisfied, the second control (active scavenging control) is terminated and normal control is started. The active scavenging completion condition may be, for example, that the estimated amount of fresh air exceeds a predetermined value (see FIG. 7(D)), or that the active scavenging control is completed for a second predetermined time (t 12 -t 10 7(A) )。 In normal control, the throttle opening is fully closed and cranking with fuel injection and ignition is performed (see Fig. 7(A) and (B)). This causes the engine 1 to start rotating autonomously. 13 When the engine start completion condition is met, the normal control ends.

[0088] [4-3] Transition from passive to active scavenging control FIG. 8 is a graph showing the time-dependent fluctuations when active scavenging control is performed during the passive scavenging control shown in FIG. 6, where (A) represents the engine speed, (B) represents the throttle opening, (C) represents the vehicle speed, (D) represents the intake manifold pressure, and (E) represents the estimated amount of fresh air introduced into the combustion chamber.

[0089] When the engine 1 is stopped, the flag is set to on (F=1) at time t0, and the electric vehicle is running in EV mode (see FIGS. 8A and 8C). At this time, if the charge rate of the high-voltage battery 5 exceeds a predetermined charge rate, passive scavenging control is initiated. In passive scavenging control, fuel injection, ignition, and cranking are not performed, and the throttle opening is set to full open (see FIGS. 8A and 8B). As a result, the intake manifold pressure becomes approximately equal to atmospheric pressure (see FIG. 8D). Furthermore, running wind is introduced into the intake passage 11, and the estimated fresh air volume gradually increases (see FIG. 8E).

[0090] When the electric vehicle stops temporarily at time t1, scavenging by the running wind is temporarily stopped, and when the electric vehicle starts moving at time t2, scavenging by the running wind is resumed (see Figures 8(C) and (E)). After that, at time t 20When the engine start conditions are met, the first control of active scavenging control is initiated. In the first control, the throttle is fully closed and cranking is performed without fuel injection or ignition (see Figures 8(A) and (B)). As a result, the estimated fresh air volume gradually increases and the intake manifold pressure gradually decreases (see Figures 8(D) and (E)).

[0091] time t 21 When the transition condition is met by the intake manifold pressure falling below a predetermined pressure, the first control ends and the second control begins (see Figures 8(A) and 8(D)). In the second control, the throttle is fully opened and cranking is performed without fuel injection or ignition (see Figures 8(A) and 8(B)). This promotes the introduction of fresh air into the combustion chamber, and the estimated fresh air amount increases rapidly (see Figure 8(E)).

[0092] time t 22 When the estimated fresh air volume exceeds a predetermined value, and the active scavenging completion condition is met, the second control (active scavenging control) ends and normal control starts (see Fig. 8(A) and (E)). In normal control, the throttle opening is fully closed, and cranking accompanied by fuel injection and ignition is performed (see Fig. 8(A) and (B)). This causes the engine 1 to start self-sustaining rotation. At time t 23 When the engine start completion condition is met, the normal control ends.

[0093] [5. Effects] (1) The engine control device 30 of this embodiment is applied to an electric vehicle equipped with an engine 1 provided with a hydraulic variable valve mechanism 10 having a lock pin, a traction motor 2, and a high-voltage battery 5. This engine control device 30 includes a setting unit 31 and a control unit 32. When the engine 1 is stopped, the setting unit 31 sets the flag to ON (F=1) if the temperature of the engine oil that drives the variable valve mechanism 10 is equal to or lower than a predetermined temperature. When the flag is on, the control unit 32 can perform passive scavenging control in EV mode, in which the vehicle travels using the driving force of the traction motor 2 while the engine 1 is stopped. Passive scavenging control is a control in which the throttle is fully opened and the inside of the combustion chamber is scavenged with the wind generated during travel in EV mode.

[0094] With this configuration, even if a backflow of exhaust gas occurs due to a poor fit of the lock pin in the variable valve mechanism 10, the exhaust gas can be discharged into the exhaust passage 14 by utilizing the wind generated by EV driving while the engine 1 is stopped. Therefore, the startability of the engine 1 can be improved regardless of the state of the lock pin in the variable valve mechanism 10. Furthermore, in electric vehicles, the engine 1 may be started during EV driving to assist acceleration. The engine control device 30 of this embodiment can improve acceleration performance in such situations.

[0095] (2) As shown in Fig. 4, the control unit 32 performs passive scavenging control when the flag is on (F = 1) and the charging rate of the high-voltage battery 5 exceeds a predetermined charging rate. This allows the passive scavenging control to be started in a state where long-term or long-distance EV driving is possible, and increases the possibility of achieving scavenging by running wind. Therefore, the startability of the engine 1 can be further improved.

[0096] (3) As shown in FIGS. 4 and 5, the control unit 32 performs active scavenging control when the flag is on (F=1) and the charging rate of the high-voltage battery 5 is equal to or lower than a predetermined charging rate. Active scavenging control is a control that scavenges the combustion chamber by cranking without performing fuel injection or ignition. This allows the active scavenging control to be started in a state where long-term or long-distance EV driving is not expected, thereby forcibly achieving scavenging. Therefore, the startability of the engine 1 can be further improved.

[0097] (4) The active scavenging control of this embodiment has a first control and a second control. The first control generates negative pressure in the combustion chamber by cranking with the throttle fully closed. The second control promotes the introduction of fresh air into the combustion chamber by cranking with the throttle fully opened after the first control. This makes it possible to progress and complete scavenging in a short time by utilizing the intake inertia effect. Therefore, the startability of the engine 1 can be further improved.

[0098] (5) As shown in Figures 4 and 5, when the control unit 32 receives a command to start the engine 1 while the passive scavenging control is being performed, it performs active scavenging control (steps B5 and B8). The active scavenging control is a control that scavenges the combustion chamber by cranking without performing fuel injection or ignition. The start-up command includes, for example, the accelerator opening exceeding a predetermined opening (the accelerator pedal being pressed hard).

[0099] In this way, when the driver requests to start the engine 1 during EV driving, the passive scavenging control is stopped and active scavenging control is immediately implemented, thereby forcibly achieving scavenging. This further improves the startability of the engine 1 and allows for an immediate response to the driver's request. For example, it becomes possible to achieve a transition from EV mode to HV mode in a short time, thereby improving the acceleration performance of the electric vehicle.

[0100] (6) The completion condition of the passive scavenging control of this embodiment (passive scavenging completion condition) may include one of the following conditions. The estimated amount of fresh air introduced into the combustion chamber exceeded a specified value. The instantaneous intake flow rate exceeded the specified flow rate. The passive scavenging control execution time has exceeded the specified passive scavenging time. The driving distance while passive scavenging control is in operation exceeds the specified distance. This allows scavenging of the engine 1 while minimizing the power consumption required to open the throttle valve 12.

[0101] [6. Other] The above-described embodiment is merely illustrative, and is not intended to exclude various modifications and applications of techniques not explicitly stated in the present embodiment. Each configuration of the present embodiment can be modified in various ways without departing from the spirit of the present embodiment. Furthermore, each configuration of the present embodiment can be selected or combined as needed.

[0102] In the above embodiment, as shown in Fig. 4, when the flag is on (F = 1) in the EV mode and the charging rate of the high-voltage battery 5 exceeds a predetermined charging rate, the passive scavenging control is started. However, the conditions for starting the passive scavenging control are not limited to this. The conditions for starting the passive scavenging control only need to include the flag being on (F = 1) in the EV mode. Additional conditions other than these can be added as appropriate.

[0103] In the above embodiment, as shown in FIG. 2, the presence or absence of "fuel injection and ignition" has been described as one of the features of each control. On the other hand, if the engine 1 is not provided with a spark plug 9, ignition itself is not necessary, and control related to ignition can be ignored. For example, if the engine 1 is a diesel engine, the passive scavenging control may be understood as "the throttle valve 12 is fully opened, the EGR valve 17 is closed, no fuel injection, and no cranking." Similarly, the active scavenging control may be understood as "control for scavenging the combustion chamber by cranking without fuel injection."

[0104] In the above embodiment, as shown in Figures 4 and 5, the active scavenging control via the No route in step B3 and the active scavenging control via the Yes route in step B5 are the same control, but they may be different. For example, in the active scavenging control via the No route in step B3, it is considered that cranking at a relatively low rotation speed is performed because there is little need to start the engine 1 in a short time. On the other hand, in the active scavenging control via the Yes route in step B5, it is considered that cranking at a relatively high rotation speed is performed because there is a high need to start the engine 1 in a short time. The control content of the active scavenging control can be set appropriately depending on the situation.

[0105] In the above embodiment, the first control and the second control are performed as the active scavenging control, but the first control can be omitted. At least, by cranking without performing fuel injection and ignition (in other words, by performing only the second control without performing the first control), the combustion chamber can be actively scavenged.

[0106] The generator 3 or the starter 6 may be used to crank the engine 1 depending on the driving environment, temperature conditions, charging rate, etc. of the electric vehicle. For example, the engine 1 may be cranked using the power of one battery with a higher battery temperature, or the engine 1 may be cranked using the power of one battery with a higher charging rate. Furthermore, the generator 3 and the starter 6 may be used together to crank the engine 1. [Industrial Applicability]

[0107] The present invention is applicable to the manufacturing industry of engine control devices mounted on electric vehicles, and also to the manufacturing industry of engines and electric vehicles equipped with engine control devices. The engine control device of the present invention is used in an electric vehicle to control an engine equipped with a variable valve mechanism having a lock pin. The engine control device of this invention is applicable to both HEVs and PHEVs. [Explanation of symbols]

[0108] 1 engine 2. Drive motor 3. Generator 4. Clutch 5 High-voltage battery (secondary battery) 6 Starter 7 Low voltage battery 8 injectors 9 Spark plugs 10 Variable valve mechanism 11 Intake passage 12 Throttle valve 13 Intake manifold 14 Exhaust passage 15 Exhaust manifold 16 EGR passage 17 EGR valve 20 Oil temperature sensor 21 Engine speed sensor 22 Intake manifold pressure sensor 23 Outside air temperature sensor 24 Airflow sensor 25 Oxygen concentration sensor 26 Accelerator pedal stroke sensor 27 Brake pedal stroke sensor 28 Vehicle speed sensor 30 Engine control device 31 Setting section 32 Control section

Claims

1. An engine control device for an electric vehicle including an engine provided with a hydraulic variable valve mechanism having a lock pin, a traction motor, and a secondary battery, a setting unit that sets a flag to ON when the temperature of engine oil that drives the variable valve mechanism is equal to or lower than a predetermined temperature when the engine is stopped; a control unit capable of implementing passive scavenging control when the flag is on in an EV mode in which the vehicle travels using the driving force of the traction motor while the engine is stopped, The passive scavenging control is a control in which the throttle is fully opened and the inside of the combustion chamber is scavenged with the running wind in the EV mode. An engine control device characterized by:

2. The control unit performs the passive scavenging control when the flag is on and the charging rate of the secondary battery exceeds a predetermined charging rate.

2. The engine control device according to claim 1.

3. the control unit performs active scavenging control when the flag is on and the charging rate of the secondary battery is equal to or lower than the predetermined charging rate in the EV mode; The active scavenging control is a control for scavenging the combustion chamber by cranking without performing fuel injection or ignition.

3. The engine control device according to claim 2.

4. The active scavenging control includes a first control for generating a negative pressure in the combustion chamber by cranking with the throttle fully closed, and a second control for promoting the introduction of fresh air into the combustion chamber by cranking with the throttle fully opened after the first control.

4. The engine control device according to claim 3.

5. the control unit performs active scavenging control when receiving a command to start starting the engine while the passive scavenging control is being performed, The active scavenging control is a control for scavenging the combustion chamber by cranking without performing fuel injection or ignition.

2. The engine control device according to claim 1.

6. The active scavenging control includes a first control for generating a negative pressure in the combustion chamber by cranking with the throttle fully closed, and a second control for promoting the introduction of fresh air into the combustion chamber by cranking with the throttle fully opened after the first control.

6. The engine control device according to claim 5.

7. The completion condition of the passive scavenging control is The estimated amount of fresh air introduced into the combustion chamber exceeds a predetermined value, or The instantaneous value of the intake flow rate exceeds a predetermined flow rate, or The implementation time of the passive scavenging control exceeds a predetermined passive scavenging time, or The traveling distance in a state where the passive scavenging control is being performed exceeds a predetermined distance.

7. The engine control device according to claim 1, wherein the engine control device comprises:

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