Control device for internal combustion engine

Abstract

To prevent generation of water droplets in an exhaust passage and freezing of water droplets on a valve seat by executing ignition timing delay control.SOLUTION: In a low temperature condition where an outside air temperature is below zero, a control device 11 for an internal combustion engine 10 performs ignition timing delay control of the internal combustion engine 10 until warming-up of the internal combustion engine 10 is completed after catalyst warming-up is completed. Through the ignition timing delay control of the internal combustion engine 10, part of energy generated through combustion of an air-fuel mixture in the internal combustion engine 10 is used for intensifying force of exhaust gas. By intensifying the force of the exhaust gas in the internal combustion engine 10, water droplets generated in a cylinder 12 and an exhaust passage 14 are blown off.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 describes a control device that performs a drive load adjustment process to adjust the drive load of a high-pressure pump so that the opening of the exhaust valve when the internal combustion engine is stopped is an opening that avoids a specified small opening when the vehicle is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-122929 Summary of the Invention [Problem to be solved by the invention]

[0004] In a control device such as that described in Patent Document 1, when an internal combustion engine is stopped, the exhaust valve is opened by avoiding a specified small opening, thereby preventing a water film from forming between the exhaust valve and the valve seat. However, if moisture is present in the exhaust passage, depending on the amount of moisture in the exhaust passage and the outside temperature, the moisture may turn into droplets and freeze on the valve seat. In this case, the exhaust valve may not be able to close completely when the engine is started, which could result in a misfire. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. One aspect of the present disclosure is a control device applied to a vehicle including an internal combustion engine having an exhaust passage, a water temperature sensor for detecting the temperature of a coolant of the internal combustion engine, and an outside air temperature sensor for detecting an outside air temperature, and controls the internal combustion engine. When the coolant temperature is equal to or lower than a first temperature that is equal to or lower than a dew point at which water droplets form in the exhaust passage and the outside air temperature is equal to or lower than a second temperature that is below the freezing point at which the water droplets freeze, the control device for the internal combustion engine executes ignition retard control to increase an ignition retard amount of the internal combustion engine after catalyst warm-up is completed, until the coolant temperature reaches or exceeds a third temperature at which the internal combustion engine has completed warm-up. [Effects of the Invention]

[0006] The control device for the internal combustion engine can suppress the generation of water droplets in the exhaust passage and the freezing of water droplets on the valve seat by executing ignition retard control of the internal combustion engine. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the configuration of an internal combustion engine and a control device for the internal combustion engine according to one embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of processing executed by the control device for an internal combustion engine according to the embodiment. [Figure 3] FIG. 3 is a time chart showing the ignition retard control executed by the control device for an internal combustion engine according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a control device for an internal combustion engine will be described below with reference to FIGS. <Configuration of the internal combustion engine 10> First, the configuration of the internal combustion engine 10, which is controlled by a control device 11 for the internal combustion engine 10, will be described with reference to FIG. 1. The internal combustion engine 10 has multiple cylinders 12. FIG. 1 shows only one of the multiple cylinders 12. An air-fuel mixture is combusted in each of the multiple cylinders 12. The internal combustion engine 10 also includes an intake passage 13, which is a passage through which intake air is introduced into the multiple cylinders 12, and an exhaust passage 14, which is a passage through which exhaust gas is discharged from the cylinders 12. The internal combustion engine 10 also includes an in-cylinder injector 15 that injects fuel into the cylinders 12 to form an air-fuel mixture. The internal combustion engine 10 also includes an ignition device 16 that ignites the air-fuel mixture in the cylinders 12 by spark discharge. A throttle valve 17 is installed in the intake passage 13. The amount of intake air introduced into the cylinders 12 can be adjusted by changing the opening of the throttle valve 17. The internal combustion engine 10 generates driving force for the vehicle by rotating a crankshaft 18 through combustion of an air-fuel mixture in the cylinders 12 .

[0009] The internal combustion engine 10 is controlled by a control device 11. Detection results of various sensors for detecting the operating conditions of the internal combustion engine 10 are input to the control device 11. The various sensors include an air flow meter 19, a vehicle speed sensor 20, an accelerator position sensor 21, a crank angle sensor 22, a water temperature sensor 23, an outside air temperature sensor 24, and a catalyst temperature sensor 25.

[0010] The air flow meter 19 is a sensor that detects the intake air volume, which is the flow rate of intake air flowing through the intake passage 13. The vehicle speed sensor 20 is a sensor that detects the speed of the vehicle. The accelerator position sensor 21 is a sensor that detects the depression amount of the accelerator pedal. The crank angle sensor 22 is a sensor that detects the crank angle, which is the rotation angle of the crankshaft 18. The water temperature sensor 23 is a sensor that detects the temperature of the coolant for the internal combustion engine 10. The outside air temperature sensor 24 is a sensor that detects the outside air temperature. The catalyst temperature sensor 25 is a sensor that detects the temperature of the catalyst 26. Based on the detection results of these sensors, the control device 11 controls the fuel injection amount and fuel injection timing of the in-cylinder injector 15, the ignition timing of the ignition device 16, the throttle opening, etc.

[0011] The catalyst 26 is configured to purify harmful components contained in the exhaust gas, such as carbon monoxide, hydrocarbons, and nitrogen oxides. <Processing Executed by the Control Device 11> The process executed by the control device 11 will be described with reference to FIG.

[0012] The process in FIG. 2 is a process in which the control device 11 executes ignition retard control of the internal combustion engine 10. While the internal combustion engine 10 is operating, the control device 11 repeatedly executes the process in FIG. 2. In step S10, the control device 11 determines whether the temperature of the coolant of the internal combustion engine 10 is equal to or lower than a first temperature. The control device 11 acquires data on the coolant temperature using the water temperature sensor 23. The first temperature is a temperature equal to or lower than the dew point at which water droplets form in the exhaust passage 14 of the internal combustion engine 10. If the temperature of the coolant is higher than the dew point, the temperature of the exhaust passage 14 is also higher than the dew point, and no water droplets form in the exhaust passage 14. If the temperature of the coolant is higher than the first temperature in step S10 (S10: NO), the control device 11 temporarily ends this series of processes. If the temperature of the coolant is equal to or lower than the first temperature in step S10 (S10: YES), the control device 11 proceeds to step S20.

[0013] Next, in step S20, it is determined whether the outside air temperature is equal to or lower than a second temperature. The control device 11 acquires outside air temperature data using the outside air temperature sensor 24. The second temperature is a sub-zero temperature at which water droplets formed in the exhaust passage 14 of the internal combustion engine 10 freeze. When the outside air temperature is below freezing, the water droplets formed in the exhaust passage 14 freeze. If the outside air temperature is higher than the second temperature in step S20 (S20: NO), the control device 11 temporarily ends this series of processes. If the outside air temperature is equal to or lower than the second temperature in step S20 (S20: YES), the control device 11 proceeds to step S30.

[0014] Next, in step S30, it is determined whether catalyst warm-up of the internal combustion engine 10 has been completed. In order for the catalyst 26, which is a purification device, to function properly, the temperature of the catalyst 26 needs to be raised to its activation temperature. The control device 11 acquires temperature data of the catalyst 26 using the catalyst temperature sensor 25. If the temperature of the catalyst 26 is below the activation temperature, the control device 11 performs catalyst warm-up. In catalyst warm-up, the control device 11 increases the ignition retard amount in each cylinder 12 of the internal combustion engine 10. The ignition retard amount is the amount by which the ignition timing is retarded from the timing at which torque is greatest. In catalyst warm-up, the ignition retard amount in all cylinders 12 is increased simultaneously. If the temperature of the catalyst 26 is equal to or higher than the activation temperature, the control device 11 terminates catalyst warm-up of the internal combustion engine 10. If catalyst warm-up has not been completed in step S30 (S30: NO), the control device 11 temporarily terminates this series of processes. If the catalyst warm-up has been completed in step S30 (S30: YES), the control device 11 proceeds to step S40.

[0015] Next, in step S40, the control device 11 executes ignition retard control. The ignition retard control in step S40 will be described with reference to FIG. 3. The control device 11 executes the ignition retard control in step S40 after catalyst warm-up is completed. The control device 11 executes the ignition retard control to delay ignition in the internal combustion engine 10. By delaying ignition, the rate at which energy generated by the combustion of the air-fuel mixture in the internal combustion engine 10 is converted into torque decreases, and the momentum of the exhaust gas is increased. By increasing the momentum of the exhaust gas, water droplets generated in the cylinders 12 and the exhaust passage 14 can be blown away. The ignition retard control by the control device 11 increases the amount of ignition retard for each cylinder 12. With reference to FIG. 3, the ignition retard control in the internal combustion engine 10 having three cylinders #1, #2, and #3 will be described.

[0016] The control device 11 completes catalyst warm-up at time t1. Next, the control device 11 increases the ignition retard amount in cylinder #1 from time t2 to time t3, compared to normal. The period from time t1 to time t3 is several seconds to several tens of seconds. At this time, the ignition retard amount in cylinders #2 and #3 is not increased. Next, the control device 11 increases the ignition retard amount in cylinder #2 from time t4 to time t5, compared to normal. The period from time t4 to time t5 is the same as the period from time t2 to time t3. At this time, the ignition retard amount in cylinders #1 and #3 is not increased. Next, the control device 11 increases the ignition retard amount in cylinder #3 from time t6 to time t7, compared to normal. The period from time t6 to time t7 is the same as the period from time t2 to time t3. At this time, the ignition retard amount in cylinders #1 and #2 is not increased. After that, the same processing as that from time t1 to time t7 is repeated. In Figure 3, the same processing as that from time t1 to time t7 is repeated from time t7 to time t13. In this way, the control of making the ignition retard amount for each cylinder 12 larger than normal is the ignition retard control.

[0017] While the control device 11 is performing the ignition retard control through the processing of step S40, the control device 11 periodically proceeds to step S50. Next, in step S50, the control device 11 determines whether the temperature of the coolant of the internal combustion engine 10 is equal to or higher than a third temperature. The control device 11 acquires data on the coolant temperature using the water temperature sensor 23. The third temperature is a temperature at which it can be determined that the warm-up of the internal combustion engine 10 is complete, based on the coolant temperature being equal to or higher than the third temperature. If the coolant temperature is lower than the third temperature in step S50 (S50: NO), the control device 11 returns to step S40 and continues to execute the ignition retard control of the internal combustion engine 10. As the operation of the internal combustion engine 10 continues, the temperature of the wall surface of the exhaust passage 14 increases. When the temperature of the wall surface of the exhaust passage 14 increases, the exhaust passage 14 dries, and water droplets are no longer generated in the exhaust passage 14, making the ignition retard control of the internal combustion engine 10 unnecessary. Furthermore, since the temperature of the catalyst 26 increases when the ignition retard control of the internal combustion engine 10 is continuously executed, it is not preferable to constantly execute the ignition retard control of the internal combustion engine 10. Therefore, in step S50, if the temperature of the cooling water is equal to or higher than the third temperature (S50: YES), the control device 11 ends this series of processes.

[0018] <Actions and Effects of This Embodiment> The control device 11 of the internal combustion engine 10 performs ignition retard control when the outside air temperature is below freezing and the catalyst has warmed up but the internal combustion engine 10 has not. By controlling the ignition retard of the internal combustion engine 10, the amount of energy generated by the combustion of the air-fuel mixture in the internal combustion engine 10 that is used to increase the momentum of the exhaust gas increases. By increasing the momentum of the exhaust gas, water droplets that have formed in the cylinders 12 and the exhaust passage 14 are blown downstream of the exhaust. This makes it possible to suppress the formation of water droplets in the exhaust passage 14 and the freezing of water droplets on the valve seat.

[0019] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0020] The control device 11 may execute the ignition retard control before the catalyst warm-up is completed. The length of the period during which the ignition retard amount is increased in the ignition timing control may be different for each cylinder 12 or for each timing.

[0021] In the ignition retard control, the periods during which the ignition retard amount is increased for a plurality of cylinders 12 may overlap. The amount of ignition retard in the ignition retard control may be different for each cylinder 12 or for each timing. [Explanation of symbols]

[0022] 10...internal combustion engine, 11...control device, 12...cylinder, 13...intake passage, 14...exhaust passage, 15...in-cylinder injector, 16...ignition device, 17...throttle valve, 18...crankshaft, 19...air flow meter, 20...vehicle speed sensor, 21...accelerator position sensor, 22...crank angle sensor, 23...water temperature sensor, 24...outside air temperature sensor, 25...catalyst temperature sensor, 26...catalyst

Claims

[Claim 1] 1. A control device for an internal combustion engine that is applied to a vehicle that includes an internal combustion engine having an exhaust passage, a water temperature sensor that detects a temperature of a cooling water of the internal combustion engine, and an outside air temperature sensor that detects an outside air temperature, and controls the internal combustion engine, When the temperature of the cooling water is equal to or lower than a first temperature, which is a temperature below a dew point at which water droplets form in the exhaust passage, and the outside air temperature is equal to or lower than a second temperature, which is a temperature below the freezing point at which water droplets freeze, After catalyst warm-up is completed, ignition retard control is executed to increase the amount of ignition retard of the internal combustion engine until the temperature of the cooling water becomes equal to or higher than a third temperature, which is the temperature at which warm-up of the internal combustion engine is completed. Control device for internal combustion engines.

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