Control device for internal combustion engine

Abstract

To inform a user of when engine operation by forced start is finished.SOLUTION: The hybrid vehicle has an internal combustion engine 11 and an electric motor as prime movers. The control device 60 executes a process of calculating an oil dilution amount which is an amount of fuel mixed in the oil stored in the oil pan 29, a process of forcibly starting the internal combustion engine 11 and operating the internal combustion engine 11 for a predetermined period when the oil dilution amount is equal to or greater than a predetermined threshold value, and a process of notifying a user of a correlation value correlated with a time from the start of the forced start to the end of the predetermined period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for an internal combustion engine. [Background technology]

[0002] For example, the vehicle described in Patent Document 1 is equipped with an internal combustion engine and an electric motor as prime movers. This vehicle is capable of EV driving, which means that the vehicle runs using only the driving force of the electric motor. If the EV driving mode desired by the user cannot be implemented, the reason for this is displayed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-222308 Summary of the Invention [Problem to be solved by the invention]

[0004] In low-temperature environments or when the engine is repeatedly operated for short periods of time, oil dilution occurs when fuel adhering to the inside of the cylinders mixes with the oil stored in the engine's oil pan. When the oil dilution amount, which is the amount of fuel mixed in the oil, exceeds a predetermined threshold, the internal combustion engine is forced to start and the engine temperature is raised, thereby performing a vaporization process to volatilize the fuel mixed in the oil.

[0005] In a vehicle capable of EV driving, vehicle users expect the vehicle to be driven in EV mode as much as possible. Therefore, when the above-described forced start of the internal combustion engine is initiated, it is desirable to notify the user when the engine operation due to the forced start will end. [Means for solving the problem]

[0006] A control device for an internal combustion engine that solves the above problem is a device for controlling an internal combustion engine of a vehicle having an internal combustion engine and an electric motor as prime movers. This control device executes the following processes: calculating an oil dilution amount, which is the amount of fuel mixed in oil stored in an oil pan of the internal combustion engine; forcibly starting the internal combustion engine and running it for a predetermined period of time if the oil dilution amount is equal to or greater than a predetermined threshold; and notifying a user of a correlation value that correlates with the time from the start of the forced start to the end of the predetermined period. [Effects of the Invention]

[0007] According to this invention, it is possible to notify the user when the engine operation due to the forced start will end. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an internal combustion engine, a drive system, and a control device in one embodiment. [Figure 2] FIG. 2 is a flowchart showing the procedure of the process executed by the control device of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of a control device for an internal combustion engine will be described below with reference to Figures 1 and 2. The internal combustion engine of this embodiment is mounted on a hybrid vehicle having an internal combustion engine and an electric motor as prime movers.

[0010] <Configuration of the internal combustion engine, drive system, and control device> As shown in FIG. 1, a hybrid system 10 of a hybrid vehicle includes an internal combustion engine 11 that burns fuel to obtain power. The internal combustion engine 11 is provided with a plurality of cylinders 12. In this embodiment, four cylinders 12 are provided. An intake passage 13 for introducing intake air into the cylinders 12 is connected to the cylinders 12. The downstream side of the intake passage 13 branches into four passages corresponding to the number of cylinders 12, and each branched passage is connected to a cylinder 12. Furthermore, a fuel injection valve 14 for supplying fuel into the cylinder 12 is attached to each branched passage.

[0011] A throttle valve 15 that opens and closes the intake passage 13 is attached upstream of the branch point in the intake passage 13. The throttle valve 15 is a so-called butterfly valve that adjusts the amount of intake air supplied to each cylinder 12 by changing the flow path cross-sectional area of ​​the intake passage 13. An air flow meter 16 that detects the intake air flow rate GA flowing through the intake passage 13 is attached upstream of the throttle valve 15 in the intake passage 13.

[0012] An exhaust passage 21 is connected to each cylinder 12 to discharge exhaust gas from the cylinder 12. The upstream side of the exhaust passage 21 branches into four passages, one for each of the cylinders 12, and each of the branched passages is connected to a cylinder 12. A catalytic converter 22 that purifies the exhaust gas is attached downstream of the branch point in the exhaust passage 21. The catalytic converter 22 oxidizes hydrocarbons contained in the exhaust gas into water and carbon dioxide, and oxidizes carbon monoxide to carbon dioxide. The catalytic converter 22 also reduces nitrogen oxides contained in the exhaust gas to nitrogen. A particulate filter 23 that collects particulate matter contained in the exhaust gas is attached downstream of the catalytic converter 22 in the exhaust passage 21.

[0013] An exhaust air-fuel ratio sensor 24 that detects the oxygen concentration in the exhaust as the exhaust air-fuel ratio R is attached downstream of the branch point in the exhaust passage 21 and upstream of the catalytic converter 22. In addition, an exhaust temperature sensor 25 that detects the exhaust temperature TE is attached downstream of the catalytic converter 22 in the exhaust passage 21 and upstream of the particulate filter 23.

[0014] A crank angle sensor 27 that detects the rotational position of the crankshaft 11A as a crank angle CA is disposed near the crankshaft 11A, which is the output shaft of the internal combustion engine 11. Although not shown, a water jacket through which coolant flows for cooling the internal combustion engine 11 is defined inside the internal combustion engine 11. A coolant temperature sensor 28 that detects the coolant temperature TW is attached to the most downstream portion of the water jacket.

[0015] The internal combustion engine 11 is provided with an oil pan 29 for storing oil to be supplied to various parts including the internal combustion engine 11. The oil stored in the oil pan 29 is pumped by an oil pump P, supplied to the internal combustion engine 11 and other devices, and then returned to the oil pan 29.

[0016] The crankshaft 11A of the internal combustion engine 11 is drivingly connected to a first motor-generator 51 via a first planetary gear mechanism 30. The first planetary gear mechanism 30 has a sun gear 31, which is an external gear, and a ring gear 32, which is an internal gear, arranged coaxially with the sun gear 31. A plurality of pinion gears 33 are arranged between the sun gear 31 and the ring gear 32, and mesh with both the sun gear 31 and the ring gear 32. Each pinion gear 33 is supported by a carrier 34 in a state in which it can freely rotate and revolve. In the first planetary gear mechanism 30 configured in this manner, the crankshaft 11A of the internal combustion engine 11 is connected to the carrier 34. The sun gear 31 is also connected to the first motor-generator 51. A ring gear shaft 35 is connected to the ring gear 32.

[0017] The ring gear shaft 35 is drivingly connected to the left and right drive wheels W via a reduction gear mechanism 56 and a differential gear 57. In addition, the ring gear shaft 35 is connected to a second motor generator 52 via a second planetary gear mechanism 40.

[0018] The second planetary gear mechanism 40 has a sun gear 41, which is an external gear, and a ring gear 42, which is an internal gear, that is arranged coaxially with the sun gear 41. 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 rotatable on its own axis but is unable to revolve. In the second planetary gear mechanism 40 configured in this manner, a ring gear shaft 35 is connected to the ring gear 42. A second motor-generator 52 is also connected to the sun gear 41.

[0019] The hybrid system 10 is equipped with a battery 53 that stores power to be supplied to the first motor generator 51 and the second motor generator 52. The battery 53 has a built-in sensor unit 53A that detects battery information IF such as the voltage between the terminals of the battery 53, the output current and input current from the battery 53, and the temperature of the battery 53.

[0020] The battery 53 is connected to the first motor generator 51 via a first inverter 54. When the first motor generator 51 functions as an electric motor, the first inverter 54 converts direct current from the battery 53 into alternating current and outputs it to the first motor generator 51. When the internal combustion engine 11 is started, the first motor generator 51 functions as an electric motor and therefore acts as a starter. When the first motor generator 51 functions as a generator, the first inverter 54 converts alternating current generated by the first motor generator 51 into direct current and supplies it to the battery 53.

[0021] The battery 53 is connected to the second motor generator 52 via the second inverter 55. When the second motor generator 52 functions as an electric motor, the second inverter 55 converts the direct current from the battery 53 into alternating current and outputs it to the second motor generator 52. When the second motor generator 52 functions as a generator, the second inverter 55 converts the alternating current generated by the second motor generator 52 into direct current and supplies it to the battery 53.

[0022] A display device 71 is attached to the instrument panel of the hybrid vehicle. This display device 71 displays notifications to convey various information to the vehicle user. Multiple speakers 72 are built into various locations in the hybrid vehicle, for example, in the doors. The speakers 72 emit notifications to convey various information to the vehicle user.

[0023] A mode changeover switch 73 is mounted near the driver's seat of the hybrid vehicle for switching between an electric vehicle mode in which the vehicle runs using only the driving force of the first motor generator 51 and the second motor generator 52.

[0024] The mode selector switch 73 is a toggle-type push button switch that switches between the above-mentioned electric vehicle mode and a hybrid mode in which the vehicle travels with the internal combustion engine. However, if other conditions for executing the electric vehicle mode are not met, the hybrid mode is executed regardless of whether the mode selector switch 73 is pressed. Examples of other conditions for executing the electric vehicle mode include the hybrid vehicle speed being less than a specified vehicle speed, the accelerator pedal depression amount being less than a specified amount, and the temperature of the battery 53 being within a specified temperature range. Furthermore, if the system activation switch (sometimes referred to as an ignition switch, etc.) of the hybrid system 10 is turned off and then on again, the hybrid mode is executed as the initial mode.

[0025] The hybrid system 10 includes a control device 60 that controls the internal combustion engine 11, the first motor-generator 51, and the second motor-generator 52 in an integrated manner. The control device 60 receives a signal indicating the intake air flow rate GA from the air flow meter 16 and a signal indicating the crank angle CA from the crank angle sensor 27. The control device 60 also receives a signal indicating the coolant temperature TW from the coolant temperature sensor 28 and information indicating battery information IF from the sensor unit 53A of the battery 53. The control device 60 also receives a signal indicating the exhaust air-fuel ratio R from the exhaust air-fuel ratio sensor 24 and a signal indicating the exhaust temperature TE from the exhaust temperature sensor 25. Although not shown, the control device 60 also receives various signals required to control the hybrid system 10, such as a signal indicating the vehicle speed of the hybrid vehicle and a signal indicating the amount of depression of the accelerator pedal.

[0026] The control device 60 includes a CPU 60A and a memory 60B including a ROM, a RAM, etc., and performs various controls by the CPU 60A executing programs stored in the memory 60B. For example, the control device 60 controls the opening of the throttle valve 15 and the amount of fuel injected from the fuel injection valve 14 in the internal combustion engine 11 based on signals from each sensor provided in the hybrid system 10. The control device 60 also controls the first inverter 54 and the second inverter 55 based on signals from each sensor provided in the hybrid system 10, thereby controlling the first motor generator 51 and the second motor generator 52.

[0027] <About volatilization treatment> The control device 60 calculates the oil dilution amount DIL, which is the amount of fuel mixed into the oil stored in the oil pan 29, at each predetermined control cycle. The calculation of the oil dilution amount DIL is well known. For example, the control device 60 calculates a larger estimated value for the amount of fuel mixed into the oil as the intake air flow rate GA input from the air flow meter 16 increases. Furthermore, the control device 60 calculates a larger estimated value for the amount of fuel mixed into the oil as the coolant temperature TW input from the coolant temperature sensor 28 increases. Furthermore, the control device 60 calculates a larger estimated value for the amount of fuel volatilizing from the oil as the coolant temperature TW input from the coolant temperature sensor 28 increases. The control device 60 then subtracts the estimated amount of fuel volatilizing from the oil from the estimated amount of fuel mixed into the oil, and adds the difference to the oil dilution amount DIL calculated in the previous cycle to calculate a new oil dilution amount DIL. In this manner, in this embodiment, the control device 60 executes a calculation process to calculate the oil dilution amount DIL.

[0028] When the oil dilution amount DIL calculated as described above becomes equal to or greater than a predetermined threshold value DILref, the control device 60 performs a volatilization process to volatilize and remove the fuel contained in the oil stored in the oil pan 29. When performing this volatilization process, the control device 60 operates the internal combustion engine 11 for a predetermined operating time T to increase the temperature of the internal combustion engine 11. As a result, the temperature of the oil stored in the oil pan 29 becomes a temperature sufficient to volatilize the fuel, and the amount of fuel contained in the oil decreases to or below the predetermined value. Note that when the oil dilution amount DIL becomes equal to or greater than the threshold value DILref while the internal combustion engine 11 is operating, the engine load is increased to further increase the temperature of the internal combustion engine 11, thereby promoting fuel volatilization.

[0029] 2 shows the procedure of the process that the control device 60 executes at predetermined intervals to execute the above-mentioned volatilization process while the internal combustion engine 11 is stopped. Note that, hereinafter, the step number of each process is represented by a number preceded by "S."

[0030] 2 starts, the control device 60 acquires the currently calculated oil dilution amount DIL and determines whether the acquired value is equal to or greater than a predetermined threshold value DILref (S100). The threshold value DILref is the oil dilution amount DIL at which the volatilization process needs to be performed, and is set in advance.

[0031] In the process of S100, when it is determined that the oil dilution amount DIL is equal to or greater than the threshold value DILref (S100), the control device 60 performs a forced start (S110) of the internal combustion engine 11. This forced start starts the operation of the internal combustion engine 11, which had been stopped until then.

[0032] Next, the control device 60 displays the count value on the display device 71 (S120). The count value is a value corresponding to the length of time from when the forced start of the internal combustion engine 11 is initiated in the processing of S110 until the elapse of the operating time T. This count value is a correlation value that correlates with the time from when the forced start of the internal combustion engine 11 is initiated until the end of the predetermined period when the internal combustion engine 11 is started and operated for the predetermined period.

[0033] The control device 60 sets a larger count value as the value of the oil dilution amount DIL acquired in S100 increases. Then, the control device 60 subtracts from the count value every time a predetermined time elapses, and displays the subtracted count value on the display device 71. The process of S120 above is a process for notifying the user of the correlation value.

[0034] Next, the control device 60 determines whether the countdown of the count value has ended (S130). In the process of S130, the control device 60 determines that the countdown of the count value has ended if the subtracted count value is "0".

[0035] If a negative determination is made in the process of S130, the control device 60 repeatedly executes the process of S120 and the process of S130 until a positive determination is made in the process of S130. On the other hand, if the determination in the processing of S130 is affirmative, the control device 60 performs engine stop to stop the engine operation of the internal combustion engine 11 (S140).

[0036] Then, when the process of S140 is completed, or when a negative determination is made in the process of S100, the control device 60 terminates this process. <Actions and Effects of This Embodiment> The control device 60 calculates the oil dilution amount DIL, which is the amount of fuel mixed in the oil stored in the oil pan 29 of the internal combustion engine 11. When the control device 60 determines that the oil dilution amount DIL is equal to or greater than the threshold value DILref, the internal combustion engine 11 is forced to start and is operated for a predetermined period. Then, the user is notified of a count value that is a correlation value correlated with the time until the end of the predetermined period and that is subtracted as time passes within the predetermined period.

[0037] In this way, the oil dilution amount DIL is reduced by forcibly starting the internal combustion engine 11. The end time of the engine operation due to the forcible start is notified to the vehicle user by the count value, which is the correlation value. Therefore, the user can know when the engine operation due to the forcible start will end.

[0038] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0039] As a process for notifying the user of the correlation value, a process for displaying the count value on the display device 71 is executed. Alternatively, the count value may be output from the speaker 72. The oil dilution amount DIL within the predetermined period may be used as the correlation value. That is, the oil dilution amount DIL, which is updated every predetermined time within the operating time T corresponding to the duration of operation of the forcibly started internal combustion engine 11, is displayed on the display device 71. Then, when the oil dilution amount DIL reaches a predetermined threshold value, the operation of the forcibly started internal combustion engine 11 may be stopped. Even in this case, the same functions and effects as those of the above embodiment can be obtained. Note that in this modified example, the oil dilution amount DIL may be output from the speaker 72.

[0040] The hybrid vehicle may include a hybrid system different from the hybrid system 10 described above. [Explanation of symbols]

[0041] 10...Hybrid system 11...Internal combustion engine 11A...Crankshaft 12...cylinder 13...Intake passage 14...Fuel injection valve 15...Throttle valve 21...Exhaust passage 22...Catalytic converter 23...Particulate filter 29...Oil pan 30...First planetary gear mechanism 40...Second planetary gear mechanism 51...First motor generator 52...Second motor generator 54...First inverter 55...Second inverter 60...Control device 71...Display device 72...Speaker 73...Mode switch

Claims

1. A device for controlling an internal combustion engine of a vehicle having an internal combustion engine and an electric motor as prime movers, A process of calculating an oil dilution amount, which is the amount of fuel mixed in the oil stored in the oil pan of the internal combustion engine; a process of forcibly starting the internal combustion engine and operating it for a predetermined period of time when the oil dilution amount is equal to or greater than a predetermined threshold value; and notifying a user of a correlation value that correlates with the time from the start of the forced start to the end of the predetermined period. Control device for internal combustion engines.

2. The correlation value is a count value that is subtracted as time passes within the predetermined period. The control device for an internal combustion engine according to claim 1.

3. The correlation value is the amount of oil dilution within the predetermined period. The control device for an internal combustion engine according to claim 1.

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