JP2020023910A - Control device for internal combustion engine - Google Patents

Abstract

Provided is a control device capable of accurately estimating a diluted fuel amount in an internal combustion engine in which a fuel introduction process is performed.
When stopping combustion in a cylinder while a crankshaft of an internal combustion engine is rotating, a control device injects fuel from a fuel injection valve to convert the fuel into unburned fuel. A fuel introduction process is performed to cause the fuel to flow out of the cylinder to the exhaust passage 21 as it is. The control device 100 executes a diluted fuel amount calculation process for calculating a diluted fuel amount, which is an amount of fuel contained in the lubricating oil of the internal combustion engine 10, and the diluted fuel amount calculation process is executed by a fuel introduction process. In the case where the fuel injection process is performed, the process includes a process of correcting the calculated diluted fuel amount to be larger than the case where the fuel introduction process is not performed.
[Selection diagram] Fig. 1

Description

  The present invention relates to a control device for an internal combustion engine.

  Patent Document 1 discloses an internal combustion engine using gasoline as a fuel. This internal combustion engine includes a three-way catalyst provided in an exhaust passage, and a filter disposed in an exhaust passage downstream of the three-way catalyst to collect particulate matter in exhaust gas.

  In the internal combustion engine described in Patent Literature 1, combustion in the cylinder may be stopped when the load applied to the internal combustion engine is low when the required torque for the internal combustion engine is reduced due to cancellation of the accelerator operation or the like. . In such a combustion stop period, a fuel cut process for stopping the fuel injection of the fuel injection valve, and a fuel introduction process for injecting the fuel from the fuel injection valve and allowing the fuel to flow out of the cylinder into the exhaust passage without burning. Is performed. According to Patent Literature 1, when the filter is regenerated, a fuel introduction process is performed. On the other hand, when the regeneration is not performed, a fuel cut process is executed.

  In the fuel introduction process, the fuel injected from the fuel injection valve flows through the exhaust passage together with the air. When the fuel is introduced into the three-way catalyst, the temperature of the three-way catalyst rises due to the combustion of the fuel. When the temperature of the three-way catalyst rises in this way, high-temperature gas flows into the filter and the temperature of the filter rises. As a result, the particulate matter trapped in the filter is burned.

US Patent Application Publication No. 2014/41362

  By the way, in the internal combustion engine, part of the fuel injected from the fuel injection valve adheres to the wall surface in the cylinder without being burned and mixes with the lubricating oil. The lubricating oil mixed with the fuel is scraped off from the wall in the cylinder as the piston reciprocates, and flows into the oil pan. When such a situation continues, the fuel dilution of the lubricating oil stored in the oil pan proceeds.

  Therefore, in an internal combustion engine, calculation of a diluted fuel amount, which is an amount of fuel contained in lubricating oil, may be performed. Here, during the execution of the above-described fuel introduction process, the fuel injected from the fuel injection valve is discharged from the cylinder without burning. Therefore, the calculation of the diluted fuel amount performed in the internal combustion engine that does not perform the above-described fuel introduction process during the operation of the engine, that is, the internal combustion engine on the premise that the fuel injected from the fuel injection valve is burned in the cylinder is performed. It is difficult to accurately estimate the amount of diluted fuel even if it is applied directly to the internal combustion engine where the processing is performed.

  A control device for an internal combustion engine for solving the above-mentioned problem is applied to an internal combustion engine that burns an air-fuel mixture containing fuel injected from a fuel injection valve in a cylinder by spark discharge of an ignition device. When the combustion in the cylinder is stopped under the condition that the crankshaft is rotating, fuel is injected from the fuel injection valve and the fuel flows out of the cylinder into the exhaust passage without burning the fuel. Execute the process. The control device executes a diluted fuel amount calculating process for calculating a diluted fuel amount which is an amount of fuel contained in the lubricating oil of the internal combustion engine, and the diluted fuel amount calculating process includes executing the fuel introduction process. In such a case, a process for correcting the amount of the diluted fuel to be larger than when the fuel introduction process is not performed is included.

  During the execution of the fuel introduction process, the fuel injected from the fuel injection valve is discharged from the cylinder without burning. Therefore, compared to the case where the air-fuel mixture is combusted in the cylinder, the time during which the fuel in the unburned state stays in the cylinder is longer during the fuel introduction process, and the amount of fuel adhering to the wall surface in the cylinder is longer. Increase. Therefore, during execution of the fuel introduction process, the amount of fuel mixed into the lubricating oil increases, as compared with the case where the air-fuel mixture is burned in the cylinder, and the amount of fuel contained in the lubricating oil increases.

  Therefore, in the configuration, when the fuel introduction process is executed, the correction is performed so that the calculated diluted fuel amount is larger than when the fuel introduction process is not executed. Therefore, even when the fuel introduction process is executed, the difference between the actual amount of fuel contained in the lubricating oil and the calculated diluted fuel amount can be suppressed, and the diluted fuel amount can be accurately estimated. Become like

FIG. 1 is a schematic diagram illustrating a configuration of a hybrid vehicle including a control device for an internal combustion engine according to an embodiment. FIG. 2 is a schematic diagram showing a configuration of the internal combustion engine of the embodiment. 5 is a flowchart showing a processing procedure executed by the control device of the embodiment. FIG. 4 is a block diagram showing a process for calculating a diluted fuel amount in the embodiment. 9 is a flowchart showing a procedure of a process of calculating an additional dilution amount in the embodiment. 9 is a flowchart showing a procedure of a subtraction dilution amount calculation process in the embodiment.

Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of a hybrid vehicle 500 (hereinafter simply referred to as a vehicle 500). As shown in FIG. 1, the vehicle 500 includes an internal combustion engine 10, a power distribution integration mechanism 40 to which the crankshaft 14 of the internal combustion engine 10 is connected, and a first motor generator 71 connected to the power distribution integration mechanism 40. And A second motor generator 72 is connected to the power distribution integration mechanism 40 via a reduction gear 50, and a drive wheel 62 is connected via a reduction mechanism 60 and a differential 61.

  The power distribution integration mechanism 40 is a planetary gear mechanism, and includes a sun gear 41 of an external gear and a ring gear 42 of an internal gear. A plurality of pinion gears 43 that mesh with both the sun gear 41 and the ring gear 42 are arranged between the sun gear 41 and the ring gear 42. Each pinion gear 43 is supported by a carrier 44 so as to be able to rotate and revolve around the sun gear 41. The first motor generator 71 is connected to the sun gear 41. The crankshaft 14 is connected to the carrier 44. A ring gear shaft 45 is connected to the ring gear 42, and both a reduction gear 50 and a reduction mechanism 60 are connected to the ring gear shaft 45.

  The reduction gear 50 is a planetary gear mechanism, and includes a sun gear 51 of an external gear to which a second motor generator 72 is connected, and a ring gear 52 of an internal gear. The ring gear shaft 45 is connected to the ring gear 52. A plurality of pinion gears 53 that mesh with both the sun gear 51 and the ring gear 52 are arranged between the sun gear 51 and the ring gear 52. Each pinion gear 53 is supported in a state where it can rotate and cannot revolve around the sun gear 51.

  The first motor generator 71 exchanges power with the battery 77 via the first inverter 75. The second motor generator 72 exchanges power with the battery 77 via the second inverter 76.

  When the output torque of the internal combustion engine 10 is input to the carrier 44 of the power distribution integration mechanism 40, the output torque is distributed to the sun gear 41 and the ring gear 42. When the first motor generator 71 rotates with the output torque distributed to the sun gear 41 side, the first motor generator 71 functions as a generator.

  On the other hand, when the first motor generator 71 functions as an electric motor, the output torque of the first motor generator 71 is input to the sun gear 41. The output torque of the first motor generator 71 input to the sun gear 41 is distributed to the carrier 44 side and the ring gear 42 side. Then, when the output torque of the first motor generator 71 is input to the crankshaft 14 via the carrier 44, the crankshaft 14 rotates. In the present embodiment, rotating the crankshaft 14 by causing the first motor generator 71 to function as an electric motor is referred to as “motoring”.

  The output torque of the internal combustion engine 10 and the output torque of the first motor generator 71 distributed to the ring gear 42 are input to the drive wheels 62 via the ring gear shaft 45, the speed reduction mechanism 60, and the differential 61.

  When the vehicle 500 decelerates, the regenerative braking force corresponding to the amount of power generated by the second motor generator 72 is generated in the vehicle 500 by causing the second motor generator 72 to function as a generator. On the other hand, when the second motor generator 72 functions as an electric motor, the output torque of the second motor generator 72 is input to the drive wheels 62 via the reduction gear 50, the ring gear shaft 45, the reduction mechanism 60, and the differential 61. Is done.

  As shown in FIG. 2, the internal combustion engine 10 has a plurality of cylinders 11 (only one is shown in FIG. 2), and a piston 12 reciprocates in each cylinder 11. Each piston 12 is connected to a crankshaft 14 via a connecting rod 13. The crankshaft 14 is rotatably supported in a crankcase 26. An oil pan 27 for storing lubricating oil is provided below the crankcase 26.

  A space above the piston 12 in the cylinder 11 is a combustion chamber 25. The intake passage 15 of the internal combustion engine 10 is provided with a throttle valve 16 and an intake valve 18 for adjusting the flow rate of intake air flowing through the intake passage 15. The internal combustion engine 10 is provided with a fuel injection valve 17 that injects fuel into the intake passage 15 and an ignition device 19 that ignites a mixture of fuel and intake by spark discharge. The exhaust gas generated in each combustion chamber 25 by the combustion of the air-fuel mixture is discharged to the exhaust passage 21 when the exhaust valve 20 is open. A three-way catalyst 22 is provided in the exhaust passage 21, and a filter 23 for collecting particulate matter contained in the exhaust gas is provided downstream of the three-way catalyst 22 in the exhaust gas.

  Further, the internal combustion engine 10 includes a blow-by gas recirculation mechanism that recirculates the blow-by gas leaked into the crankcase 26 through the space between the peripheral wall of the cylinder 11 and the piston 12 to the intake passage 15. The blow-by gas recirculation mechanism includes a first blow-by bus passage 31 that connects the intake passage 15 upstream of the throttle valve 16 and the inside of the crankcase 26, a suction passage 15 downstream of the throttle valve 16 and the crankcase 26. And a second blow-by gas passage 32 that communicates with the inside. A PCV valve 33 is provided in the second blow-by gas passage 32. The PCV valve 33 opens when the pressure in the intake passage 15 downstream of the throttle valve 16 in the intake passage 15 becomes lower than a specified value, and permits the recirculation of blow-by gas from the crankcase 26 to the intake passage 15. It is configured to be.

  In the internal combustion engine 10, combustion of the air-fuel mixture in the cylinder 11 may be stopped when the vehicle 500 is running and the crankshaft 14 is rotating. The period during which the combustion of the air-fuel mixture in the cylinder 11 is stopped while the crankshaft 14 is rotating is hereinafter referred to as a “combustion stop period”. During the combustion stop period, the piston 12 reciprocates in synchronization with the rotation of the crankshaft 14. Therefore, the air introduced into the cylinder 11 through the intake passage 15 is discharged to the exhaust passage 21 without being used for combustion.

  In the combustion stop period described above, a fuel cut process for stopping the fuel injection of each fuel injection valve 17 or the fuel is injected from each fuel injection valve 17 to leave the fuel unburned from each cylinder 11 to the exhaust passage 21. Either one of the fuel introduction processes to be discharged is executed.

  When the fuel introduction process is executed, the fuel injected from each fuel injection valve 17 flows through the exhaust passage 21 together with the air, so that the fuel is introduced into the three-way catalyst 22. At this time, when the temperature of the three-way catalyst 22 is equal to or higher than the activation temperature, and the three-way catalyst 22 has a sufficient amount of oxygen to burn the fuel, the fuel is burned by the three-way catalyst 22. I do. When the fuel is burned by the three-way catalyst 22, the temperature of the three-way catalyst 22 rises and high-temperature gas flows into the filter 23, and the temperature of the filter 23 rises. When the temperature of the filter 23 becomes equal to or higher than the combustible temperature of the particulate matter in a state where oxygen is supplied to the filter 23, the particulate matter trapped by the filter 23 burns and the filter 23 is regenerated. You.

  The vehicle 500 includes an engine control device 100 that performs various controls of the internal combustion engine 10, a motor control device 300 that performs various controls of the first motor generator 71 and the second motor generator 72, and a control device for the engine. 100 and a vehicle control device 200 that integrally controls the motor control device 300. The vehicle 500 is equipped with a battery monitoring device 400 that monitors the state of charge (SOC) of the battery 77.

  Battery monitoring device 400 is connected to battery 77. The battery monitoring device 400 includes a central processing unit (CPU) and a memory, and inputs the current IB, the voltage VB, and the temperature TB of the battery 77. Then, battery monitoring device 400 calculates the state of charge SOC of battery 77 by causing the CPU to execute a program stored in the memory based on the current IB, voltage VB, and temperature TB.

  The motor control device 300 is connected to the first inverter 75 and the second inverter 76. The motor control device 300 includes a central processing unit (CPU) and a memory. When the CPU executes the program stored in the memory, the motor control device 300 controls the amount of power supplied from the battery 77 to the first motor generator 71 and the second motor generator 72, The amount of electric power (that is, the amount of charge) supplied from second motor generator 72 to battery 77 is controlled.

  The engine control device 100, the motor control device 300, and the battery monitoring device 400 are connected to the vehicle control device 200 via a communication port. The vehicle control device 200 also includes a central processing unit (CPU) and a memory, and executes various controls by the CPU executing a program stored in the memory.

  The storage amount SOC of the battery 77 is input from the battery monitoring device 400 to the vehicle control device 200. Further, the vehicle control device 200 includes an accelerator pedal sensor 86 that detects a driver's accelerator pedal depression amount (accelerator operation amount ACP), a vehicle speed sensor 87 that detects a vehicle speed VS that is a traveling speed of the vehicle 500, A power switch 88 is connected, and output signals from these sensors and switches are input. The power switch 88 is a switch for starting the system of the hybrid vehicle 500, and when the vehicle driver turns on the power switch 88, the vehicle 500 is in a runnable state. Hereinafter, a period from when the power switch 88 is turned on by the vehicle driver to when the power switch 88 is turned off next time is referred to as “one trip”.

  Then, vehicle control device 200 calculates the required vehicle power, which is the required value of the driving force of vehicle 500, based on accelerator operation amount ACP and vehicle speed VS. Further, the vehicle control device 200 determines the engine required torque, which is the required value of the output torque of the internal combustion engine 10, and the required value of the power running torque or the regenerative torque of the first motor generator 71 based on the vehicle required power, the charged amount SOC, and the like. , And the second motor required torque, which is the required value of the powering torque or the regenerative torque of the second motor generator 72, respectively. Then, the engine control device 100 controls the output of the internal combustion engine 10 according to the engine required torque, and the motor control device 300 controls the first motor generator 71 and the second motor required torque according to the first motor required torque and the second motor required torque. By performing the torque control of second motor generator 72, the torque control required for traveling of vehicle 500 is performed.

  The engine control device 100 includes a central processing unit (hereinafter referred to as a CPU) 110, a ROM 120 storing control programs and data, a RAM 130 serving as a work area when the CPU 110 executes the programs, and electrically rewriting data. And a non-volatile memory 140 capable of performing the following operations. The CPU 110 executes programs stored in the ROM 120 to execute various engine controls.

  The engine control device 100 includes an air flow meter 81 that detects an intake air amount GA, a water temperature sensor 82 that detects a cooling water temperature THW that is a temperature of cooling water of the internal combustion engine 10, and a crank angle that detects a rotation angle of the crankshaft 14. Sensors 85 are connected, and output signals from the various sensors are input. Further, the engine control device 100 includes a first air-fuel ratio sensor 83 provided in the exhaust passage 21 upstream of the three-way catalyst 22 to detect the upstream-side air-fuel ratio Afu, A second air-fuel ratio sensor 84 that is provided in the exhaust passage 21 and detects the downstream air-fuel ratio Afd is also connected, and output signals from the respective air-fuel ratio sensors are also input.

  The engine control device 100 calculates the engine speed NE based on the output signal Scr of the crank angle sensor 85. Further, the engine control device 100 calculates the engine load factor KL based on the engine speed NE and the intake air amount GA. The engine load factor KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is operated in a steady state with the throttle valve 16 fully opened at the current engine rotation speed NE. Note that the cylinder inflow air amount is the amount of air flowing into each of the cylinders 11 during the intake stroke.

  The engine control device 100 calculates a catalyst temperature Tsc, which is the temperature of the three-way catalyst 22, and a filter temperature Tf, which is the temperature of the filter 23, based on various engine operating states such as the charging efficiency of the intake air and the engine speed NE. . Further, the engine control device 100 calculates the PM accumulation amount Ps, which is the accumulation amount of the particulate matter in the filter 23, based on the engine speed NE, the engine load factor KL, the filter temperature Tf, and the like.

  When the air-fuel mixture is burned in the cylinder 11, the engine control device 100 controls the ignition timing of the air-fuel mixture so that the spark discharge of the ignition device 19 is performed at the timing when the piston 12 reaches the vicinity of the compression top dead center. I do. On the other hand, the engine control device 100 stops the spark discharge of the ignition device 19 during the above-described combustion stop period. In addition, the engine control device 100 performs the spark discharge of the ignition device 19 when the condition for stopping the combustion of the air-fuel mixture in the cylinder 11 described later is not satisfied, and when the condition for stopping the combustion is satisfied. , The spark discharge of the ignition device 19 is stopped.

  In addition, when the execution condition of the fuel introduction process described later is satisfied and the execution of the fuel introduction process is requested during the combustion stop period, the engine control device 100 sends the above-described control to the vehicle control device 200. Request execution of motoring. When the execution of the motoring is requested, the vehicle control device 200 requests the motor control device 300 to drive the first motor generator 71. Then, the motor control device 300 controls the driving of the first motor generator 71 to perform the above-described motoring. Through the drive control of the first motor generator 71, the rotation speed of the crankshaft 14 during the combustion stop period is controlled.

  Next, referring to FIG. 3, a procedure of a process executed by the engine control device 100 to control the driving of the fuel injection valve 17 will be described. Note that the series of processing illustrated in FIG. 3 is realized by the CPU 110 repeatedly executing a program stored in the ROM 120 at predetermined intervals. In the following, step numbers are represented by numbers prefixed with “S”.

  In the series of processes shown in FIG. 3, the CPU 110 first determines whether a condition for stopping combustion of the air-fuel mixture in the cylinder 11 is satisfied (S100). For example, when the engine required torque is equal to or less than “0”, the CPU 110 determines that the condition for stopping combustion is satisfied. On the other hand, when the engine required torque is greater than “0”, the CPU 110 determines that the condition for stopping combustion is satisfied. It is determined that the condition is not satisfied.

  When it is determined in S100 that the condition for stopping combustion is not satisfied (S100: NO), the CPU 110 calculates a required value QPR of the fuel injection amount of the fuel injection valve 17 (S110). In S110, the CPU 110 calculates the required value QPR of the fuel injection amount through feedback control so that the upstream air-fuel ratio Afu becomes the target air-fuel ratio Aft. Subsequently, the CPU 110 controls the driving of the fuel injection valve 17 based on the request value QPR calculated in S110 (S120). When the drive control of the fuel injection valve 17 is executed in S120, the combustion of the air-fuel mixture in the cylinder 11 is performed. Then, the CPU 110 ends the present process once.

  On the other hand, when it is determined in S100 that the condition for stopping combustion is satisfied (S100: YES), CPU 110 determines whether or not the above-described execution condition of the fuel introduction process is satisfied (S130). ). In the present embodiment, when both the following conditions (A) and (B) are satisfied, the CPU 110 determines that the execution condition of the fuel introduction process is satisfied.

  (Condition A): The catalyst temperature Tsc, which is the temperature of the three-way catalyst 22, is equal to or higher than a specified temperature. This condition is set for the following reason. That is, even if unburned fuel is introduced into the three-way catalyst 22, if the temperature of the three-way catalyst 22 is low, the fuel may not be burned. Therefore, the specified temperature is set in advance as a criterion for determining whether the unburned fuel introduced into the three-way catalyst 22 can be burned. The activation temperature of the three-way catalyst 22 or a temperature slightly higher than the activation temperature is set as the specified temperature.

  (Condition B): The PM accumulation amount Ps of the filter 23 is equal to or more than a specified amount. This condition is set for the following reason. That is, as the amount of accumulated particulate matter collected by the filter 23 increases, the filter 23 is more clogged. Therefore, the above-described specified amount is set in advance as a criterion for determining whether or not clogging has progressed to the extent that the filter 23 needs to be regenerated.

  Then, if it is determined in S130 that the execution condition of the fuel introduction process is not satisfied (S130: NO), CPU 110 sets request value QPR of the fuel injection amount to "0" (S140). Subsequently, the CPU 110 controls the driving of the fuel injection valve 17 based on the required value QPR set in S140 (S150). When the drive control of the fuel injection valve 17 is executed in S150, no fuel is injected from the fuel injection valve 17 because the required value QPR is set to “0”. That is, the fuel cut process is executed during the combustion stop period. Then, the CPU 110 ends the present process once.

  On the other hand, if it is determined in S130 that the execution condition of the fuel introduction process is satisfied (S130: YES), CPU 110 calculates a required value QPR for the fuel introduction process (S160). When it is determined that the execution condition of the fuel introduction process is satisfied, the motoring is executed as described above.

  The required value QPR for the fuel introduction process is a required value QPR of the fuel injection amount for executing the fuel introduction process during the combustion stop period, and the required value QPR of the fuel injection amount calculated in S160 is the same as the cylinder 11 Is smaller than the required value QPR calculated when the air-fuel mixture is burned. Therefore, when the fuel injected from the fuel injection valve 17 is introduced into the cylinder 11 based on the required value QPR calculated in S160, the air-fuel ratio in the cylinder 11 causes the air-fuel mixture to burn in the cylinder 11. The value is leaner than the air-fuel ratio at the time.

  Subsequently, the CPU 110 controls the driving of the fuel injection valve 17 based on the request value QPR calculated in S160 (S170). When the drive control of the fuel injection valve 17 is executed in S170, fuel is injected from the fuel injection valve 17 even during the combustion stop period, and the fuel introduction process is performed. Then, the CPU 110 ends the present process once.

  In the internal combustion engine 10, part of the fuel injected from the fuel injection valve 17 adheres to the wall surface in the cylinder 11 and mixes with the lubricating oil that lubricates the wall surface. The lubricating oil diluted by this fuel is scraped off from the wall inside the cylinder 11 with the reciprocating motion of the piston 12 and flows into the oil pan 27. If such a situation continues, the fuel dilution of the lubricating oil stored in the oil pan 27 proceeds, so that the amount of diluted fuel, which is the amount of fuel contained in the lubricating oil, increases. On the other hand, when the temperature of the lubricating oil in the oil pan 27 increases, the fuel mixed in the lubricating oil volatilizes, and the amount of the diluted fuel decreases. The fuel volatilized from the lubricating oil is introduced into the intake passage 15 via the second blow-by gas passage 32 of the blow-by gas recirculation mechanism.

The engine control device 100 of the present embodiment executes a diluted fuel amount calculation process shown in FIG. 4 in order to calculate the diluted fuel amount DA which is an estimated value of the diluted fuel amount.
The process shown in FIG. 4 is realized by the CPU 110 executing a program stored in the ROM 120 of the engine control device 100.

  The additional dilution amount calculation processing M10 is based on the first integrated intake air amount SGA1, the post-start operation time STM, the starting water temperature THWs, the second integrated intake air amount SGA2, and the first introduction water temperature THWfs. This is a process for calculating an additional dilution amount DAad, which is an estimated value of the amount of. Hereinafter, the first start of the internal combustion engine 10 in one trip is referred to as “initial start”.

  The first integrated intake air amount SGA1 is an integrated value of the intake air amount GA from the first start of the internal combustion engine 10. The post-start operation time STM is an integrated value of the operation time of the internal combustion engine 10 from the time when the internal combustion engine 10 is first started. The starting water temperature THWs is the cooling water temperature THW when the internal combustion engine 10 is first started. The second integrated intake air amount SGA2 is an integrated value of the intake air amount GA during execution of the above-described fuel introduction process. The initial introduction water temperature THWfs is the cooling water temperature THW at the time of the first execution of the fuel introduction processing in one trip. The specific processing content of the addition dilution amount calculation processing M10 will be described later.

The addition process M20 is a process of adding the addition dilution amount DAad to the previous value DAold of the dilution fuel amount DA.
The subtraction dilution amount calculation processing M30 is based on the first integrated intake air amount SGA1, the starting water temperature THWs, and the sum (DAold + DAad) of the previous value DAold calculated in the addition processing M20 and the addition dilution amount DAad (DAold + DAad). This is a process for calculating a subtraction dilution amount DAsub which is an estimated value of the amount of fuel volatilized from the lubricating oil. Specific processing contents of the subtraction dilution amount calculation processing M30 will be described later.

  The subtraction process M40 is a process of calculating the current dilution fuel amount DA by subtracting the subtraction dilution amount DAsub from the sum (DAold + DAad) of the previous value DAold and the addition dilution amount DAad calculated in the addition process M20.

  When the power switch 88 is turned off, the CPU 110 writes the current value of the diluted fuel amount DA into the nonvolatile memory 140 as the backup value DApv. When the power switch 88 is turned on next time, the CPU 110 sets the backup value DApv read from the nonvolatile memory 140 as an initial value of the previous value DAold described above.

  During the execution of the fuel introduction process, the fuel injected from the fuel injection valve 17 is discharged from the cylinder 11 without burning. Therefore, compared to the case where the air-fuel mixture is burned in the cylinder 11, the time during which the fuel in the unburned state stays in the cylinder is longer during the fuel introduction process, and adheres to the wall surface in the cylinder 11. The amount of fuel increases. Therefore, during the execution of the fuel introduction process, the amount of fuel mixed into the lubricating oil increases and the amount of fuel contained in the lubricating oil increases as compared with the case where the air-fuel mixture is burned in the cylinder 11. .

  Therefore, in the present embodiment, when there is an execution history of the fuel introduction process, the addition dilution amount DAad is calculated so as to be larger than when there is no execution history of the fuel introduction process. The calculated diluted fuel amount DA is increased.

  FIG. 5 shows a processing procedure of an additional dilution amount calculation process M10 for calculating the additional dilution amount DAad. The process shown in FIG. 5 is realized by the CPU 110 executing a program stored in the ROM 120 of the engine control device 100 at predetermined intervals after the internal combustion engine 10 is first started.

  In a series of processes shown in FIG. 5, the CPU 110 determines whether the calculation condition of the additional dilution amount DAad is satisfied (S200). If any of the following conditions (C) or (D) is satisfied during one trip, the CPU 110 determines that the calculation condition of the additional dilution amount DAad is satisfied.

  Condition (C): The amount of fuel dissolved in the lubricating oil is saturated. This condition is set for the following reason. That is, the amount of fuel dissolved into the lubricating oil gradually increases when the internal combustion engine 10 is started. Then, when the temperature of the combustion chamber 25 rises to a certain temperature or higher due to the heat energy generated by the combustion of the air-fuel mixture, the amount of the fuel dissolved into the lubricating oil is saturated. This is because when the temperature of the combustion chamber 25 increases, the fuel supplied into the cylinder 11 vaporizes before adhering to the wall surface inside the cylinder 11. Therefore, the CPU 110 determines that the first integrated intake air amount SGA1 correlated with the total amount of heat energy generated by the combustion of the air-fuel mixture in the combustion chamber 25 after the start of the internal combustion engine 10 is equal to or greater than the predetermined first determination integrated amount SGATh. , It is determined that the amount of fuel dissolved into the lubricating oil is saturated.

Condition (D): The power switch 88 is turned off before it is determined that the amount of fuel dissolved in the lubricating oil is saturated.
Then, if the CPU 110 determines that the calculation condition of the additional dilution amount DAad is not satisfied (S200: NO), the CPU 110 sets the additional dilution amount DAad to “0” (S220), and ends this process once.

  On the other hand, if the CPU 110 determines that the calculation condition of the additional dilution amount DAad is satisfied (S200: YES), the CPU 110 sets the dilution fuel amount DA from the time when the internal combustion engine 10 is first started until the calculation condition is satisfied. A first addition amount DAad1, which is an estimated value of the increase amount, is calculated (S210). In S210, the CPU 110 calculates the first addition amount DAad1 by using the following Expression 1.

DAad1 = DAad1B × Kw1 (1)
DAad1B: First basic addition amount Kw1: First water temperature correction coefficient

In the above equation 1, the first basic addition amount DAad1B is a base value of the first addition amount DAad1, and is calculated based on the first integrated intake air amount SGA1 and the post-start operation time STM. More specifically, the first integrated intake air amount SGA1 is a value correlated with the integrated value of the amount of fuel supplied into the cylinder 11, and the larger the first integrated intake air amount SGA1, the more the fuel adhering to the cylinder 11 Since the amount increases, the amount of fuel mixed into the lubricating oil also increases. Therefore, the first basic addition amount DAad1B is calculated such that the larger the first integrated intake air amount SGA1, the larger the first basic addition amount DAad1B.

  Further, when the temperature of the lubricating oil adhering to the wall surface in the cylinder 11 increases with an increase in the post-start operation time STM, fuel is mixed into the lubricating oil adhering to the wall surface in the cylinder 11. However, since the amount of volatilization increases thereafter, the amount of fuel finally mixed into the lubricating oil decreases. Therefore, the first basic addition amount DAad1B is calculated such that the longer the post-start operation time STM, the smaller the first basic addition amount DAad1B.

  The first water temperature correction coefficient Kw1 is a value calculated based on the starting water temperature THWs. More specifically, since the wall surface temperature in the cylinder 11 is lower as the starting water temperature THWs is lower, the fuel attached to the wall surface in the cylinder 11 is less likely to be vaporized, and the amount of fuel mixed into the lubricating oil increases. Therefore, the first water temperature correction coefficient Kw1 is calculated so that the value of the first water temperature correction coefficient Kw1 becomes larger as the starting water temperature THWs becomes lower. The first addition amount DAad1 calculated as described above is a large amount.

  After calculating the first addition amount DAad1, the CPU 110 next determines whether or not there is an execution history of the fuel introduction process (S230). In step S230, the CPU 110 determines whether there is an execution history of the fuel introduction process by referring to a flag whose value is changed from “OFF” to “ON” when the fuel introduction process is executed. This flag is used to determine whether or not there is an execution history of the fuel introduction process during one trip. When the addition dilution amount calculation process M10 is completed after the power switch 88 is turned off, “OFF” is set. Is reset to

  Then, when determining that there is an execution history of the fuel introduction process (S230: YES), the CPU 110 calculates the second addition amount DAad2 (S240). This second addition amount DAad2 is a correction value of the addition dilution amount DAad, and when the execution history of the fuel introduction process is present, the dilution fuel amount DA is larger than when there is no execution history of the fuel introduction process. It is a value for correcting so as to be, and more specifically, the following value. That is, when the amount of fuel mixed into the lubricating oil out of the fuel injected from the fuel injection valve 17 is defined as the mixed fuel amount, the mixed fuel per unit fuel injection amount when the air-fuel mixture is burned in the cylinder 11 This is a value calculated as a value for compensating for the difference between the amount and the mixed fuel amount per unit fuel injection amount during execution of the fuel introduction process. Then, the CPU 110 calculates the second addition amount DAad2 using Expression 2 shown below.

DAad2 = DAad2B × Kw2 (2)
DAad2B: Second basic addition amount Kw2: Second water temperature correction coefficient

In the above equation 2, the second basic addition amount DAad2B is a base value of the second addition amount DAad2, and is calculated based on the second integrated intake air amount SGA2 and the post-start operation time STM. More specifically, the second integrated intake air amount SGA2 is a value correlated with the integrated value of the fuel amount supplied into the cylinder 11 during the execution of the fuel introduction process. Since the amount of fuel adhering to the cylinder 11 during the execution of the fuel introduction process also increases, the amount of fuel mixed into the lubricating oil also increases. Therefore, the second basic addition amount DAad2B is calculated such that the larger the second integrated intake air amount SGA2, the larger the second basic addition amount DAad2B.

  Further, as described above, when the temperature of the lubricating oil attached to the wall surface in the cylinder 11 increases as the post-start operation time STM increases, the amount of fuel finally mixed into the lubricating oil becomes Less. Therefore, the second basic addition amount DAad2B is calculated such that the longer the post-start operation time STM, the smaller the second basic addition amount DAad2B.

  Further, the second water temperature correction coefficient Kw2 is a value calculated based on the first introduction water temperature THWfs. More specifically, the lower the water temperature THWfs at the time of the first introduction is, the lower the wall surface temperature in the cylinder 11 is. Therefore, the fuel adhered to the wall surface in the cylinder 11 during the first execution of the fuel introduction process is less likely to be vaporized and mixed into the lubricating oil. The amount of fuel increases. Therefore, the second water temperature correction coefficient Kw2 is calculated so that the value of the second water temperature correction coefficient Kw2 becomes larger as the first time water temperature THWfs becomes lower. The second addition amount DAad2 calculated based on is large.

  Next, the CPU 110 calculates the sum of the first addition amount DAad1 calculated in S210 and the second addition amount DAad2 calculated in S240, and sets the calculation result as the addition dilution amount DAad (S260). In this case, the additional dilution amount DAad is increased and corrected by the second addition amount DAad2 calculated in S240. That is, if there is an execution history of the fuel introduction processing, the increase correction of the addition dilution amount DAad by the second addition amount DAad2 is performed. Then, the CPU 110 ends the present process once.

On the other hand, in S230, when determining that there is no execution history of the fuel introduction process (S230: NO), the CPU 110 sets the second addition amount DAad2 to “0” (S250).
Next, the CPU 110 calculates the sum of the first addition amount DAad1 calculated in S210 and the second addition amount DAad2 set in S250, and sets the calculation result as the addition dilution amount DAad (S260). In this case, since the value of the second addition amount DAad2 set in S250 is “0”, the addition dilution amount DAad calculated in the process of S260 is the same as the first addition amount DAad1 calculated in S210. Become. That is, when there is no execution history of the fuel introduction process, the correction of the addition dilution amount DAad by the second addition amount DAad2 is not performed. Then, the CPU 110 ends the present process once.

  FIG. 6 shows a processing procedure of the subtraction dilution amount calculation processing M30. The process shown in FIG. 6 is realized by the CPU 110 executing a program stored in the ROM 120 of the engine control device 100 at predetermined intervals after the internal combustion engine 10 is first started.

  In a series of processes shown in FIG. 6, CPU 110 determines whether or not it is time to calculate subtraction dilution amount DAsub (S300). In this S300, the CPU 110 determines whether or not the elapsed time TME from the time when the subtraction dilution amount DAsub was last updated is equal to or longer than the specified time TMTh, and when the elapsed time TME is equal to or longer than the specified time TMTh, It is determined that it is time to calculate the subtraction dilution amount DAsub.

  Then, if the CPU 110 determines that it is not the timing for calculating the subtraction dilution amount DAsub (S300: NO), the CPU 110 sets the subtraction dilution amount DAsub to “0” (S320), and terminates this process once.

  On the other hand, in S300, if the CPU 110 determines that it is time to calculate the subtraction dilution amount DAsub (S300: YES), the CPU 110 next calculates the subtraction dilution amount DAsub (S310). In S310, the CPU 110 calculates the subtraction dilution amount DAsub using Expression 3 shown below.

DAsub = DAsubB × Koil (3)
DAsubB: Basic subtraction amount Koil: Oil temperature correction coefficient

In the above formula 3, the basic subtraction amount DAsubB is a base value of the subtraction dilution amount DAsub, and is calculated by the addition process M20 in FIG. 4, that is, the previous value DAold of the dilution fuel amount DA and the addition dilution amount calculation process M10. It is calculated based on the sum (DAold + DAad) with the added dilution amount DAad. More specifically, as the amount of fuel in the lubricating oil increases, the amount of fuel volatilized from the lubricating oil within the specified time TMTh increases, and therefore, the basic subtraction increases as the sum of the previous value DAold and the additional dilution amount DAad increases. The basic subtraction amount DAsubB is calculated so that the amount DAsubB becomes a large amount.

  Further, the oil temperature correction coefficient Koil is a value calculated based on the estimated oil temperature THWo of the lubricating oil. More specifically, as the temperature of the lubricating oil increases, the amount of fuel volatilized from the lubricating oil in the oil pan 27 increases, and the amount of fuel contained in the lubricating oil decreases. Therefore, the CPU 110 calculates the estimated oil temperature THWo of the lubricating oil in the oil pan 27 based on, for example, the first integrated intake air amount SGA1 and the starting water temperature THWs. Then, the oil temperature correction coefficient Koil is calculated such that the higher the estimated oil temperature THWo, the larger the value of the oil temperature correction coefficient Koil becomes. Thus, the higher the estimated oil temperature THWo, the more the oil temperature correction coefficient Koil is calculated based on the above equation 3. The subtracted dilution amount DAsub is a large amount.

After calculating the subtraction dilution amount DAsub in this way, the CPU 110 ends the present process once.
In the present embodiment, as described above, when either the condition (C) or the condition (D) is satisfied during one trip, the additional dilution amount DAad is calculated, and the dilution fuel amount DA is updated based on the additional dilution amount DAad. Is performed. Further, every time the specified time TMTh elapses after the first start of the internal combustion engine 10, the subtracted dilution amount DAsub is calculated, and the diluted fuel amount DA is updated by the subtracted dilution amount DAsub.

According to the embodiment described above, the following operation and effect can be obtained.
(1) When the fuel introduction process is executed, the amount of fuel mixed into the lubricating oil is larger than when the fuel introduction process is not executed. Therefore, in the present embodiment, when the fuel introduction process is executed, the second addition amount DAad2 is calculated and the addition dilution amount DAad is increased and corrected, so that the fuel introduction process is executed. , The dilution fuel amount DA is corrected so as to be larger than when the fuel introduction process is not performed. Therefore, even when the fuel introduction process is executed, it is possible to suppress the difference between the actual amount of fuel contained in the lubricating oil and the calculated diluted fuel amount DA, and to estimate the diluted fuel amount DA. The accuracy will be improved.

The present embodiment can be implemented with the following modifications. The present embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.
In the above embodiment, the spark discharge of the ignition device 19 is stopped during the execution of the fuel introduction process. However, the ignition device 19 may be caused to perform spark discharge at a time when the air-fuel mixture does not burn in the cylinder 11 during execution of the fuel introduction process. For example, when spark discharge is performed when the piston 12 is located near the bottom dead center, the air-fuel mixture is not burned in the cylinder 11 where the spark discharge has been performed. Therefore, even if spark discharge is performed during execution of the fuel introduction process, the fuel injected from the fuel injection valve 17 can flow out of the cylinder 11 to the exhaust passage 21 without burning.

  The internal combustion engine to which the control device for the internal combustion engine is applied may include an in-cylinder injection valve that is a fuel injection valve that injects fuel directly into the cylinder 11. In this case, during execution of the fuel introduction process, fuel may be injected into the cylinder 11 from the in-cylinder injection valve, and the fuel may flow out to the exhaust passage 21 without burning. Thus, unburned fuel can be introduced into the three-way catalyst 22.

  The hybrid vehicle system may be another system different from the system shown in FIG. 1 as long as the rotation speed of the crankshaft 14 can be controlled by driving the motor.

  The control device of the internal combustion engine may be embodied as a device that controls an internal combustion engine mounted on a vehicle having no power source other than the internal combustion engine. Even in such an internal combustion engine mounted on a vehicle, combustion of the air-fuel mixture in the cylinder may be stopped while the crankshaft 14 is rotating by inertia. If the conditions for executing the fuel introduction process are satisfied during such a combustion stop period, the fuel introduction process is executed.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder, 12 ... Piston, 13 ... Connecting rod, 14 ... Crankshaft, 15 ... Intake passage, 16 ... Throttle valve, 17 ... Fuel injection valve, 18 ... Intake valve, 19 ... Ignition device, 20 ... exhaust valve, 21 ... exhaust passage, 22 ... three-way catalyst, 23 ... filter, 25 ... combustion chamber, 26 ... crankcase, 27 ... oil pan, 31 ... first blow-by bus passage, 32 ... second blow-by gas passage, 33: PCV valve, 40: power distribution integration mechanism, 41: sun gear, 42: ring gear, 43: pinion gear, 44: carrier, 45: ring gear shaft, 50: reduction gear, 51: sun gear, 52: ring gear, 53: pinion gear, 60: reduction mechanism, 61: differential, 62: drive wheel, 71: first motor generator, 72 ... 2 motor generator, 75 first inverter, 76 second inverter, 77 battery, 81 air flow meter, 82 water temperature sensor, 83 first air-fuel ratio sensor, 84 second air-fuel ratio sensor, 85 crank angle Sensor 86, accelerator pedal sensor 87 vehicle speed sensor 88 power switch 100 engine control device 110 central processing unit (CPU) 120 ROM ROM 130 RAM 140 non-volatile memory 200 Vehicle control device, 300: motor control device, 400: battery monitoring device, 500: hybrid vehicle (vehicle).

Claims (1)

It is applied to an internal combustion engine that burns a mixture containing fuel injected from a fuel injection valve in a cylinder by spark discharge of an ignition device,
When stopping combustion in the cylinder under the condition that the crankshaft of the internal combustion engine is rotating, fuel is injected from the fuel injection valve, and the fuel is left unburned from the cylinder to the exhaust passage. In the control device of the internal combustion engine that executes the fuel introduction process to be discharged,
Executing a diluted fuel amount calculation process of calculating a diluted fuel amount which is an amount of fuel contained in the lubricating oil of the internal combustion engine,
The control apparatus for the internal combustion engine, wherein the diluted fuel amount calculation process includes a process of correcting the amount of the diluted fuel to be larger when the fuel introduction process is performed than when the fuel introduction process is not performed. .