Control device for internal combustion engine

Abstract

To properly execute individual cylinder retard control to suppress deterioration of the drivability and emissions of a vehicle mounted with an internal combustion engine.SOLUTION: A control device for an internal combustion engine executes individual cylinder retard control of independently retarding the ignition timing for each of a plurality of cylinders of the internal combustion engine mounted on a vehicle, when predetermined execution conditions are satisfied. The control device determines whether or not execution of the individual cylinder retard control is predicted to cause deterioration of combustion in at least one cylinder, and determines whether or not combustion in at least one cylinder deteriorates. When execution of the individual cylinder retard control is predicted to cause deterioration of combustion in at least one cylinder and when combustion in at least one cylinder deteriorates, the control device prohibits execution of the individual cylinder retard control regardless of whether the execution conditions are satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a control device for an internal combustion engine mounted on a vehicle.

Background Art

[0002] Conventionally, in order to minimize the influence of knocking, a control device for an internal combustion engine that performs cylinder-by-cylinder retard control to correct the ignition timing to the retard side for each of a plurality of cylinders is known (see, for example, Patent Document 1). This control device detects a knock intensity parameter representing the intensity of knocking for each cylinder, and calculates a correction degree parameter representing the degree to which the ignition timing should be corrected to the retard side for each cylinder according to the detected knock intensity parameter. Then, the control device determines the ignition timing for each cylinder by correcting the ignition timing to the retard side for each cylinder according to the calculated correction degree parameter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By performing cylinder-by-cylinder retard control as described above, it is possible to suppress the occurrence of knocking and also suppress the exciting force in a cylinder so that the vibration of the internal combustion engine is not amplified after explosion in a cylinder where the vibration transmission sensitivity is high. However, when cylinder-by-cylinder retard control is performed, there is also a risk of deteriorating the drivability and emissions of a vehicle equipped with the internal combustion engine.

[0005] Therefore, the main object of the present disclosure is to appropriately perform cylinder-by-cylinder retard control and suppress deterioration of the drivability and emissions of a vehicle equipped with an internal combustion engine.

Means for Solving the Problems

[0006] The control device for an internal combustion engine of the present disclosure is a control device for an internal combustion engine that executes cylinder-by-cylinder retard control to independently retard the ignition timing of the internal combustion engine mounted on a vehicle for each of a plurality of cylinders when a predetermined execution condition is satisfied. The control device determines whether or not deterioration of combustion in at least one of the cylinders is predicted by the execution of the cylinder-by-cylinder retard control, and determines whether or not combustion in at least one of the cylinders has deteriorated. When deterioration of combustion in at least one of the cylinders is predicted by the execution of the cylinder-by-cylinder retard control, and when combustion in at least one of the cylinders has deteriorated, the execution of the cylinder-by-cylinder retard control is prohibited regardless of the satisfaction of the execution condition.

[0007] The control device for an internal combustion engine of the present disclosure executes cylinder-by-cylinder retard control to independently retard the ignition timing of the internal combustion engine mounted on a vehicle for each of a plurality of cylinders when a predetermined execution condition is satisfied. Further, when deterioration of combustion in at least one of the cylinders is predicted by the execution of the cylinder-by-cylinder retard control, and when combustion in at least one of the cylinders has deteriorated, the control device prohibits the execution of the cylinder-by-cylinder retard control regardless of the satisfaction of the above execution condition. Thereby, it becomes possible to appropriately execute the cylinder-by-cylinder retard control so that combustion in at least one cylinder does not become unstable or the combustion state does not further deteriorate, and to suppress deterioration of drivability and emissions of a vehicle equipped with the internal combustion engine.

[0008] Further, the control device may be configured to determine that deterioration of combustion in at least one of the cylinders is predicted by the execution of the cylinder-by-cylinder retard control when at least any one of retard control for catalyst warm-up, retard control for raising the temperature of a particulate filter, and retard control during idling operation is being executed. Thereby, it becomes possible to preferably suppress deterioration of combustion in at least one cylinder due to the execution of the cylinder-by-cylinder retard control.

[0009] Furthermore, when an abnormality occurs in a predetermined sensor, when the internal combustion engine is started while the temperature of the internal combustion engine is equal to or higher than a predetermined temperature, when the integrated intake air amount is less than a predetermined threshold immediately after the start of the internal combustion engine, and when the rotational speed of the internal combustion engine is less than a predetermined rotational speed immediately after the start of the internal combustion engine, the control device may determine that combustion in at least one of the cylinders has deteriorated. Thereby, when combustion in at least one cylinder becomes unstable, it becomes possible to satisfactorily suppress further deterioration of combustion in the cylinder by executing the cylinder-by-cylinder retard control.

[0010] In addition, the vehicle may include at least one electric motor capable of outputting driving power for traveling in addition to the internal combustion engine, and the threshold value compared with the integrated intake air amount immediately after the intermittent start of the internal combustion engine may be set smaller than the threshold value compared with the integrated intake air amount immediately after the first start of the internal combustion engine. Thereby, it is possible to suppress the execution of the cylinder-by-cylinder retard control from being restricted more than necessary, and to satisfactorily suppress the occurrence of knocking and vehicle vibration.

[0011] Furthermore, the cylinder-by-cylinder retard control may set a retard amount according to the rotational speed and intake air amount of the internal combustion engine for each of the plurality of cylinders using predetermined constraints.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Next, embodiments for carrying out the invention of the present disclosure will be described with reference to the drawings.

[0014] FIG. 1 is a schematic configuration diagram of a hybrid vehicle (HEV) 1 which is a vehicle including a control device for an internal combustion engine of the present disclosure. The hybrid vehicle 1 shown in the figure includes an engine 2, a single pinion type planetary gear 3 as a power distribution mechanism, a gear train 4, motor generators MG1 and MG2 which are both synchronous generator motors (three-phase alternating current motors), a battery (power storage device) 5, a power control unit (hereinafter referred to as "PCU") 6 which is connected to the battery 5 and drives the motor generators MG1 and MG2, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 100 which controls the entire vehicle.

[0015] The engine 2 of the hybrid vehicle 1 is a gasoline engine (in this embodiment, for example, an in-line three-cylinder engine) that converts the reciprocating motion of a piston 21 accompanying the combustion of a mixture of a hydrocarbon-based fuel and air in a plurality of cylinders (combustion chambers) 20 formed in an engine block into a rotational motion of a crankshaft (output shaft) 22. Further, the engine 2 includes, as an exhaust gas purification device, an upstream purification device 23 and a downstream purification device 24 each incorporated in an exhaust pipe. The upstream purification device 23 includes a NOx storage type exhaust gas purification catalyst (three-way catalyst) that purifies harmful components such as CO (carbon monoxide), HC, and NOx in the exhaust gas from each cylinder 20 of the engine 2. The downstream purification device 24 includes a particulate filter PF (GPF) that collects particulate matter (fine particles) in the exhaust gas and is disposed downstream of the upstream purification device 23. In this embodiment, the particulate filter PF is a porous filter carrying a NOx storage type exhaust gas purification catalyst (three-way catalyst). That is, the downstream purification device 24 includes a four-way catalyst having a purification function of a three-way catalyst and a function of collecting particulate matter.

[0016] Furthermore, the engine 2 is controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 200 as the control device of the present disclosure. The engine ECU 200 includes a microcomputer having a CPU, ROM, RAM, input / output interface, etc. (not shown), various drive circuits, various logic ICs, etc. The engine ECU 200 acquires detection values of a crank angle sensor that detects the rotational position (crank position) of the crankshaft 22, an air flow meter that detects the intake air amount Qa, a throttle opening sensor that detects the opening degree of a throttle valve (not shown), an upstream air-fuel ratio sensor that detects the air-fuel ratio of the exhaust gas flowing into the upstream purification device 23, a downstream air-fuel ratio sensor that detects the air-fuel ratio of the exhaust gas flowing into the downstream purification device 24, a water temperature sensor that detects the water temperature Tw of the cooling water that cools the engine block, etc. (all not shown) via an input port (not shown).

[0017] The engine ECU 200 calculates the rotational speed Ne of the engine 2 (crankshaft 22) based on the crank position from the crank angle sensor. Further, the engine ECU 200 calculates the integrated intake air amount AQ during one trip of the hybrid vehicle 1 based on the intake air amount Qa from the air flow meter. Furthermore, the engine ECU 200 calculates the load factor KL based on the intake air amount Qa from the air flow meter and the rotational speed Ne of the engine 2. The load factor KL is the ratio of the volume of air actually inhaled during one cycle to the stroke volume per cycle of the engine 2. Also, the engine ECU 200 controls the throttle valve (intake air amount Qa), a plurality of fuel injection valves (fuel injection amount), a plurality of spark plugs (ignition timing), etc. based on the rotational speed Ne, load factor KL, etc. Furthermore, the engine ECU 200 mainly executes ignition timing retard control for warming up the exhaust gas purification catalyst of the upstream purification device 23, ignition timing retard control for raising the temperature of the particulate filter of the downstream purification device 24, and ignition timing retard control during idling operation. The retard control for warming up the upstream purification device 23, the retard control for warming up the downstream purification device 24, and the retard control during idling operation all set the same retard amount for each cylinder 20 of the engine 2.

[0018] In addition, when predetermined execution conditions are satisfied, the engine ECU 200 executes cylinder-by-cylinder retard control to independently retard the ignition timing of the engine 2 for each of the plurality of cylinders 20. In the present embodiment, the execution conditions for the cylinder-by-cylinder retard control are that the coolant temperature Tw indicating the temperature of the engine 2 is equal to or higher than a predetermined execution permission temperature Ta (for example, -20°C), and the rotational speed Ne of the engine 2 is equal to or lower than a predetermined upper limit rotational speed Na (for example, 4000 rpm). When the execution conditions for the cylinder-by-cylinder retard control are satisfied and the prohibition conditions for the cylinder-by-cylinder retard control are not satisfied, the engine ECU 200 derives values corresponding to the rotational speed Ne and the intake air amount Qa acquired in step S100 from a retard amount setting map (constraint) created (adapted) in advance so as to define the relationship between the rotational speed Ne and the intake air amount Qa of the engine 2 and the retard amount for each of the plurality of cylinders 20. Then, the engine ECU 200 sets the values derived from the retard amount setting map for each of the plurality of cylinders 20 as the retard amount, and sets the ignition timing for each cylinder 20 based on the retard amount and the base ignition timing or the like.

[0019] The planetary gear 3 is a differential rotation mechanism including a sun gear 3s, a ring gear 3r, and a planetary carrier 3c that rotatably supports a plurality of pinion gears 3p. As shown in FIG. 1, the sun gear 3s is connected to the rotor of the motor generator MG1, and the planetary carrier 3c is connected to the crankshaft 22 of the engine 2 via a damper mechanism DD. Further, the ring gear 3r rotates coaxially and integrally with the counter drive gear 4a (output member) of the gear train 4. The gear train 4 includes, in addition to the counter drive gear 4a, a counter driven gear 4b and a final drive gear (drive pinion gear) 4c. The final drive gear 4c meshes with the differential ring gear Dr of the differential gear DF, and is connected to the left and right wheels (drive wheels) W via the differential gear DF and the drive shaft DS. Thereby, the planetary gear 3, the gear train 4, and the differential gear DF constitute a transaxle that transmits a part of the output torque of the engine 2 as a power generation source to the wheels W and connects the engine 2 and the motor generator MG1 to each other.

[0020] The motor generator MG1 mainly operates as a generator that converts at least part of the power from the engine 2 being under load operation into electric power. Also, the motor generator MG2 is connected to the left and right wheels W via a differential gear DF including a drive gear 4d, a counter drive gear 4b, a final drive gear 4c, a differential ring gear Dr, and a drive shaft DS. The motor generator MG2 mainly operates as an electric motor that is driven by at least either one of the electric power from the battery 5 and the electric power from the motor generator MG1 to generate driving torque on the drive shaft DS.

[0021] The battery 5 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The battery 5 is managed by a battery management electronic control unit (hereinafter referred to as "battery ECU") 500 including a microcomputer having a CPU or the like (not shown). The battery ECU 500 derives the SOC (state of charge) of the battery 5, the allowable charging power Win (negative value), the allowable discharging power Wout (positive value), etc. based on the inter-terminal voltage VB of the battery 5, the charge and discharge current IB of the battery 5, the battery temperature Tb of the battery 5, etc.

[0022] The PCU 6 includes a first inverter that drives the motor generator MG1, a second inverter that drives the motor generator MG2, a boost converter that can boost the electric power from the battery 5 and step down the electric power from the motor generators MG1 and MG2 sides (all not shown). The PCU 6 is controlled by a motor electronic control unit (hereinafter referred to as "MGECU") 600 including a microcomputer having a CPU or the like (not shown).

[0023] The HVECU 100 includes a microcomputer having a CPU and the like, various drive circuits, various logic ICs, and the like. As shown in FIG. 3, the HVECU 100 acquires the vehicle speed V detected by a vehicle speed sensor (not shown), the accelerator opening Acc indicating the depression amount of an accelerator pedal (not shown) detected by an accelerator pedal position sensor, the shift position SP of a shift lever (not shown) detected by a shift position sensor, and the like. Further, the HVECU 100 exchanges information with the above-mentioned ECUs 200, 500, 600 and a brake electronic control unit (not shown) that controls a hydraulic brake actuator (not shown), etc., and comprehensively controls the hybrid vehicle 1 based on the vehicle speed V, the accelerator opening Acc, signals from the respective ECUs 200, 500, 600, and the like. Also, the HVECU 100 intermittently stops or starts (restarts) the engine 2 in cooperation with the engine ECU 200 and the MGECU 600 based on the driver's output request, the state of the battery 5, and the like.

[0024] Subsequently, with reference to FIGS. 2 and 3, the execution procedure of the cylinder-by-cylinder retard control by the engine ECU 200 will be described.

[0025] FIGS. 2 and 3 are flowcharts showing a cylinder-by-cylinder retard control routine that is executed at predetermined time intervals (micro time intervals) by the engine ECU 200 while the engine 2 is being operated (including during the engine start-up process) after the hybrid vehicle 1 is system-started. When the execution timing of the cylinder-by-cylinder retard control routine arrives, the engine ECU 200 acquires information necessary for control, such as the coolant temperature Tw from a coolant temperature sensor, the engine speed Ne calculated separately, the intake air amount Qa detected by an air flow meter, the integrated intake air amount AQ calculated separately, and the flags Fct, Fpf, Fid, Fsf, Fest, as shown in FIG. 2 (step S100).

[0026] Flag Fct is turned on mainly while the ignition timing retard control for warming up the exhaust gas purification catalyst of the upstream purification device 23 is being executed, and is turned off when the retard control is not being executed. Flag Fpf is turned on mainly while the ignition timing retard control for raising the temperature of the particulate filter of the downstream purification device 24 is being executed, and is turned off when the retard control is not being executed. Flag Fid is turned on mainly while the retard control during idle operation is being executed, and is turned off when the retard control is not being executed. Flag Fsf is turned on when any abnormality occurs in the sensors necessary for ensuring the combustion stability in each cylinder 20, such as the air flow meter, the upstream air-fuel ratio sensor, and the downstream air-fuel ratio sensor, and is turned off when no abnormality occurs in these sensors. Flag Fest is turned on when the starting process of the engine 2 is being executed, and is turned off in response to the completion of the starting process.

[0027] Next, the engine ECU 200 determines whether the coolant temperature Tw acquired in step S100 is equal to or higher than the above-described execution permission temperature Ta (step S110). When the coolant temperature Tw is equal to or higher than the execution permission temperature Ta, the engine ECU 200 determines whether the rotational speed Ne acquired in step S100 is equal to or lower than the above-described upper limit rotational speed Na (step S120). When the coolant temperature Tw is equal to or higher than the execution permission temperature Ta and the rotational speed Ne is equal to or lower than the upper limit rotational speed Na, and the execution condition for the cylinder-by-cylinder retard control is satisfied (step S120: YES), the engine ECU 200 determines whether the flag Fct acquired in step S100 is off (step S130). When the flag Fct is off and the ignition timing retard control for warming up the exhaust gas purification catalyst of the upstream purification device 23 is not being executed (step S130: YES), the engine ECU 200 determines whether the flag Fpf acquired in step S100 is off (step S140). When the flag Fpf is off and the ignition timing retard control for raising the temperature of the particulate filter of the downstream purification device 24 is not being executed (step S140: YES), the engine ECU 200 determines whether the flag Fid acquired in step S100 is off (step S150).

[0028] When the flag Fid is off and the retard control during idle operation is not being executed (step S150: YES), as shown in FIG. 3, the engine ECU 200 determines whether the flag Fsf acquired in step S100 is off (step S160). When the flag Fsf is off and the sensors necessary for ensuring the combustion stability in each cylinder 20, such as the air flow meter, the upstream air-fuel ratio sensor, and the downstream air-fuel ratio sensor, are normal (step S160: YES), the engine ECU 200 determines whether the starting process of engine 2 is being executed based on the flag Fest acquired in step S100 (step S170).

[0029] If the startup process of Engine 2 is being executed and Engine 2 is starting up (step S170: YES), Engine ECU 200 determines whether the coolant temperature Tw acquired in step S100 is less than or equal to a predetermined temperature Th (step S180). The predetermined temperature Th used as a threshold value in step S180 is, for example, a temperature within the range of 110 - 120°C. If the coolant temperature Tw is less than or equal to the predetermined temperature Th and Engine 2 has not been started (restarted) in a high-temperature state (step S180: YES), Engine ECU 200 deems that the execution conditions for cylinder-by-cylinder retard control are satisfied and the prohibition conditions for cylinder-by-cylinder retard control during the startup of Engine 2 are not satisfied. Then, Engine ECU 200 sets, for each of the plurality of cylinders 20, a retard amount corresponding to the rotational speed Ne and the intake air amount Qa acquired in step S100 using a retard amount setting map (constraint) defined for each of the plurality of cylinders 20 (step S240), and once terminates the cylinder-by-cylinder retard control routine.

[0030] Also, if the startup process of Engine 2 is not being executed (Engine 2 is not starting up) (step S170: NO), Engine ECU 200 determines whether Engine 2 has just been started based on the on / off state of the flag Fest (step S190). If Engine 2 has just been started (step S190: YES), Engine ECU 200 determines whether the most recent startup of Engine 2 is the first startup after the startup of the system of the hybrid vehicle 1 (one trip) (step S200). If the most recent startup of Engine 2 is the first startup (step S200: YES), Engine ECU 200 sets a positive value A0 predetermined for a threshold value AQref to be compared with the integrated intake air amount AQ acquired in step S100 (step S210). Also, if the most recent startup of Engine 2 is not the first startup but a restart (intermittent startup) after the operation of Engine 2 has been once stopped during one trip (step S200: NO), Engine ECU 200 sets a positive value A1 smaller than the value A0 to the threshold value AQref (step S215).

[0031] After the process of step S210 or S215, the engine ECU 200 determines whether the integrated intake air amount AQ obtained in step S100 is equal to or greater than the threshold value AQref (step S220). When it is determined that the integrated intake air amount AQ is equal to or greater than the threshold value AQref and the combustion in each cylinder 20 is recognized as being stable (step S220: YES), the engine ECU 200 further determines whether the rotational speed Ne of engine 2 obtained in step S100 is equal to or greater than a predetermined rotational speed N0 (step S230). When the rotational speed Ne of engine 2 is equal to or greater than the predetermined rotational speed N0 and has sufficiently increased immediately after startup (step S230: YES), the engine ECU 200 considers that the execution condition of the cylinder-by-cylinder retard control is satisfied and the prohibition condition of the cylinder-by-cylinder retard control immediately after the startup of engine 2 is not satisfied. Further, when the startup process of engine 2 is not being executed and it is not immediately after the completion of the startup process of engine 2 (step S190: NO), the engine ECU 200 considers that the execution condition of the cylinder-by-cylinder retard control is satisfied and the prohibition condition of the cylinder-by-cylinder retard control is not satisfied. In these cases as well, the engine ECU 200 sets, for each of the plurality of cylinders 20, a retard amount corresponding to the rotational speed Ne and the intake air amount Qa obtained in step S100 using a retard amount setting map (constraint) defined for each of the plurality of cylinders 20 (step S240), and once terminates the cylinder-by-cylinder retard control routine.

[0032] On the other hand, when any one of the flags Fct, Fpf, and Fid is on (step S130: NO, step S140: NO, or step S150: NO), the engine ECU 200 prohibits the execution of cylinder-specific retard control (step S250) and temporarily ends the cylinder-specific retard control routine without setting the retard amount for each of the plurality of cylinders 20. That is, when the flag Fct is on and the ignition timing retard control for warming up the exhaust gas purification catalyst of the upstream purification device 23 is being executed (step S130: NO), when the flag Fpf is on and the ignition timing retard control for raising the temperature of the particulate filter of the downstream purification device 24 is being executed (step S140: NO), and when the flag Fid is on and the retard control during idling operation is being executed (step S150: NO), if the ignition timing is further retarded independently for each cylinder 20 by the cylinder-specific retard control routine, the combustion state in each cylinder 20 may become unstable (deteriorate). Based on this, in the hybrid vehicle 1, even if the water temperature Tw is equal to or higher than the execution permission temperature Ta and the rotational speed Ne is equal to or lower than the upper limit rotational speed Na, and the execution conditions for cylinder-specific retard control are satisfied (step S120: YES), when any one of the flags Fct, Fpf, and Fid is on (step S130: NO, step S140: NO, or step S150: NO), the execution of cylinder-specific retard control is prohibited (step S250).

[0033] Also, when the flag Fsf is on (step S160: NO), when the coolant temperature Tw exceeds the predetermined temperature Th (step S180: NO), when the integrated intake air amount AQ is less than the threshold value AQref (step S220: NO), or when the engine speed Ne of engine 2 is less than the predetermined engine speed N0 (step S230: NO), the engine ECU 200 prohibits the execution of cylinder-by-cylinder ignition retard control (step S250) and temporarily terminates the cylinder-by-cylinder ignition retard control routine without setting the ignition retard amount for each of the plurality of cylinders 20. That is, when the flag Fsf is on and there is some abnormality in at least any one of the sensors necessary to ensure the combustion stability in each cylinder 20 such as an air flow meter (step S160: NO), when the coolant temperature Tw exceeds the predetermined temperature Th and the engine 2 is started (restarted) in a high-temperature state (step S180: NO), when the integrated intake air amount AQ immediately after the start of engine 2 is less than the threshold value AQref (step S220: NO), and when the engine speed Ne is less than the predetermined engine speed N0 and has not increased sufficiently immediately after the start of engine 2 (step S230: NO), there is a risk that the combustion state deteriorates in at least one cylinder 20, and if the ignition timing is further retarded independently for each cylinder 20 by the cylinder-by-cylinder ignition retard control routine, the combustion state in the at least one cylinder 20 may deteriorate further. Based on this, in the hybrid vehicle 1, even when the coolant temperature Tw is equal to or higher than the execution permission temperature Ta and the engine speed Ne is equal to or lower than the upper limit engine speed Na and the execution conditions for cylinder-by-cylinder ignition retard control are satisfied (step S120: YES), if a negative determination is made in any of steps S160, S180, S220, and S230 (step S160: NO, step S180: NO, step S220: NO, or step S230: NO), the execution of cylinder-by-cylinder ignition retard control is prohibited (step S250).

[0034] As described above, when the predetermined execution conditions are satisfied (step S120: YES), the engine ECU 200 of the hybrid vehicle 1 executes cylinder-by-cylinder retard control (step S240) to independently retard the ignition timing of the engine 2 mounted on the hybrid vehicle 1 for each of the plurality of cylinders 20. Further, when it is predicted that combustion deterioration will occur in at least one cylinder 20 due to the execution of the cylinder-by-cylinder retard control (step S130: NO, step S140: NO, or step S150: NO), and when combustion has deteriorated in at least one cylinder 20 (step S160: NO, step S180: NO, step S220: NO, or step S230: NO), the engine ECU 200 prohibits the execution of the cylinder-by-cylinder retard control (step S250) regardless of the satisfaction of the above execution conditions. Thereby, it becomes possible to appropriately execute the cylinder-by-cylinder retard control so that combustion in at least one cylinder 20 does not become unstable or the combustion state does not deteriorate further, and to favorably suppress the deterioration of drivability and emissions of the hybrid vehicle 1 equipped with the engine 2.

[0035] Further, when at least any one of the retard control for warming up the catalyst of the upstream purification device 23, the retard control for raising the temperature of the particulate filter of the downstream purification device 24, and the retard control during idling operation is being executed, the engine ECU 200 determines that combustion deterioration is predicted in at least one cylinder 20 due to the execution of the cylinder-by-cylinder retard control (steps S130, S140, S150). Thereby, it becomes possible to favorably suppress the deterioration of combustion in at least one cylinder 20 due to the execution of the cylinder-by-cylinder retard control.

[0036] Furthermore, when an abnormality occurs in a predetermined sensor such as an air flow meter (step S160: NO), when the engine 2 is started in a state where the coolant temperature Tw indicating the temperature of the engine 2 is equal to or higher than a predetermined temperature Th (step S180: NO), when the integrated intake air amount AQ is less than a predetermined threshold value AQref immediately after the start of the engine 2 (step S220: NO), and when the rotational speed Ne is less than a predetermined rotational speed N0 immediately after the start of the engine 2 (step S230: NO), the engine control unit 200 may determine that the combustion in at least one cylinder 20 has deteriorated. As a result, when the combustion in at least one cylinder 20 becomes unstable, it is possible to preferably suppress further deterioration of the combustion in the cylinder 20 by executing the cylinder-by-cylinder retard control.

[0037] In addition, in the hybrid vehicle 1 including the motor generator MG2 capable of outputting driving power in addition to the engine 2, the threshold value AQref compared with the integrated intake air amount AQ immediately after the intermittent start of the engine 2 is set smaller than the threshold value AQref compared with the integrated intake air amount AQ immediately after the first start in one trip of the engine 2 (steps S210, S215). As a result, it is possible to suppress the execution of the cylinder-by-cylinder retard control from being restricted more than necessary in step S220, and to preferably suppress the occurrence of knocking and vibration of the hybrid vehicle 1.

[0038] Note that the application target of the engine ECU 200 that executes the cylinder-by-cylinder retard control as described above is not limited to the hybrid vehicle 1 including the two motor generators MG1 and MG1, and may be a so-called single-motor hybrid vehicle. Further, the above-described engine ECU 200 may be applied to a vehicle including only the engine 2 as a power generation source for running. Furthermore, the engine 2 is not limited to an in-line three-cylinder engine, and may be an in-line four-cylinder engine, an in-line six-cylinder engine, a V-type six-cylinder engine, or the like. Also, the engine 2 may include a supercharger and may be an LPG engine. Further, the cylinder-by-cylinder retard control executed by the engine ECU 200 sets a retard amount corresponding to the engine speed Ne and the intake air amount Qa for each of the plurality of cylinders 20 using a retard amount setting map determined for each of the plurality of cylinders 20, but is not limited thereto. That is, the cylinder-by-cylinder retard control may set, for example, a retard amount corresponding to the engine speed Ne and the intake pressure of the engine 2 for each of the plurality of cylinders 20. Also, in step S240, the retard amount used for setting the ignition timing of each cylinder 20 may be set to gradually change, for example, at a constant rate to a value corresponding to the engine speed Ne and the intake air amount Qa obtained from the above retard amount setting map. Furthermore, when the execution of the cylinder-by-cylinder retard control is prohibited during its execution, in step S250, the retard amount used for setting the ignition timing of each cylinder 20 may be set to gradually change from a value corresponding to the engine speed Ne and the intake air amount Qa obtained from the above retard amount setting map to zero at a constant rate.

[0039] And needless to say, the invention of the present disclosure is not limited to the above embodiment, and various changes can be made within the scope of the disclosure. Further, the above embodiment is merely a specific form of the invention described in the summary section of the invention, and does not limit the elements of the invention described in the summary section of the invention.

Industrial Applicability

[0040] The invention of the present disclosure can be used in the manufacturing industries of internal combustion engines and vehicles.

Description of Symbols

[0041] 1 Hybrid vehicle, 2 Engine, 20 Cylinders, 21 Pistons, 22 Crankshaft, 23 Upstream purification device, 24 Downstream purification device, 200 Engine electronic control unit (Engine ECU), 4 Gear trains, 3 Planetary gears, 5 Battery, 6 Power control unit (PCU), MG1, MG2 Motor generators.

Claims

1. A control device for an internal combustion engine that performs individual cylinder retard control for retarding an ignition timing of each of a plurality of cylinders of an internal combustion engine mounted on a vehicle when a predetermined execution condition is satisfied, A control device for an internal combustion engine that determines whether or not execution of the individual cylinder retard control is expected to result in deterioration of combustion in at least one of the cylinders, and determines whether or not combustion in at least one of the cylinders has deteriorated, and when execution of the individual cylinder retard control is expected to result in deterioration of combustion in at least one of the cylinders, and when combustion in at least one of the cylinders has deteriorated, prohibits execution of the individual cylinder retard control regardless of whether the execution condition is met.

2. 2. The control device for an internal combustion engine according to claim 1, A control device for an internal combustion engine that, when at least one of a retard control for warming up a catalyst, a retard control for raising the temperature of a particulate filter, and a retard control during idling is being executed, determines that the execution of the individual cylinder retard control will predict a deterioration of combustion in at least one of the cylinders.

3. 3. The control device for an internal combustion engine according to claim 1, A control device for an internal combustion engine that determines that combustion in at least one of the cylinders is deteriorating when an abnormality occurs in a specified sensor, when the internal combustion engine is started with the temperature of the internal combustion engine being equal to or higher than a specified temperature, when the accumulated intake air volume is less than a predetermined threshold value immediately after starting the internal combustion engine, and when the rotation speed of the internal combustion engine is less than a specified rotation speed immediately after starting the internal combustion engine.

4. 4. The control device for an internal combustion engine according to claim 3, The vehicle includes, in addition to the internal combustion engine, at least one electric motor capable of outputting power for traveling, A control device for an internal combustion engine, wherein the threshold value compared with the accumulated intake air amount immediately after an intermittent start of the internal combustion engine is set to be smaller than the threshold value compared with the accumulated intake air amount immediately after an initial start of the internal combustion engine.

5. 2. The control device for an internal combustion engine according to claim 1, The cylinder-by-cylinder retard control is a control device for an internal combustion engine that sets a retard amount for each of the plurality of cylinders according to the rotation speed and intake air amount of the internal combustion engine using predetermined constraints.

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