Control device for internal combustion engine

Abstract

A control device for an internal combustion engine capable of executing ignition delay control for delaying an ignition timing for igniting an air-fuel mixture in a combustion chamber than during normal operation, the control device being provided with: a per-cylinder torque calculation unit for calculating the amount of deviation in combustion torque for each cylinder; an injection amount correction unit that corrects the fuel injection amount to each cylinder so as to reduce the amount of deviation in the combustion torque of each cylinder calculated by the per-cylinder torque calculation unit; and a misfire determination unit that determines misfire of a predetermined cylinder on the basis of the combustion torque of the predetermined cylinder among the cylinders, and does not perform correction of the fuel injection amount to each cylinder by the injection amount correction unit when the combustion torque of any one of the cylinders is equal to or less than a predetermined torque.

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine capable of changing the timing of igniting a mixture gas. Background Art

[0002] Japanese Patent Application Laid-Open No. 2008-297933 describes a control device configured to retard the ignition timing of the engine compared to normal when preheating a catalyst device for purifying exhaust gas output from the engine. The control device is configured to calculate the crankshaft speed to suppress the difference in torque generated in each cylinder due to the retardation of the ignition timing for preheating the catalyst device as described above. Furthermore, the control device is configured to control the fuel injection amount of each cylinder to suppress the deviation of the calculated crankshaft speed.

[0003] In addition, Japanese Patent Publication No. 2017-141791 describes a control device that heats up a gasoline particulate filter (GPF) that captures particulate matter (PM) in the exhaust gas of the engine, and burns and removes the PM accumulated on the GPF. The control device determines to execute GPF regeneration control to burn and remove PM when the pressure difference before and after the GPF reaches a specified pressure or above. The control device is configured to retard the ignition timing of the engine compared to a case where the GPF regeneration control is not executed when it is determined that the GPF regeneration control needs to be executed. In addition, the boost pressure is increased by reducing the opening of the exhaust bypass valve, thereby suppressing the reduction in engine output caused by the execution of the GPF regeneration control.

[0004] Moreover, Japanese Patent Publication No. 2022-062848 describes a control device for appropriately judging misfire even when the ignition timing is delayed to preheat the catalyst, thereby making the combustion of the engine unstable. The control device is configured to judge the presence or absence of misfire based on the change in the measured time required for the crankshaft to rotate 30°CA due to the combustion of the cylinder as the judgment object. Specifically, the control device is configured to subtract the measured time one cycle ago from the latest measured time when the delay control for preheating the catalyst is not performed. The control device is configured to judge that misfire has occurred when the value obtained by subtracting the measured time one cycle ago from the latest measured time is greater than the prescribed time. When the delay control is performed, the five shorter measured times of the measured time from the past 10 cycles ago are extracted and the average value is taken, and the latest measured time is subtracted from the average value. The control device is configured to judge that misfire has occurred when the value obtained by subtracting the latest measured time from the average value is greater than the prescribed time. Summary of the invention

[0005] According to the control device described in Japanese Patent Application Laid-Open No. 2008-297933 and Japanese Patent Application Laid-Open No. 2017-141791, the ignition timing of the engine is delayed when the catalyst device is preheated or the GPF is regenerated. Since the ignition timing of the engine is delayed in this way, the combustion of the engine becomes unstable. In order to suppress the deviation of the crankshaft speed, the control device described in Japanese Patent Application Laid-Open No. 2008-297933 is configured to control the amount of fuel injected into each cylinder based on the deviation of the crankshaft speed. That is, according to the control device described in Japanese Patent Application Laid-Open No. 2008-297933, the deviation of the crankshaft speed is suppressed.

[0006] On the other hand, the control device described in Japanese Patent Application Laid-Open No. 2022-062848 determines the presence or absence of misfire based on the amount of change in the time required for the crankshaft to rotate a predetermined crankshaft angle. Therefore, when the fuel injection amount is controlled to suppress the deviation of the crankshaft speed as in the control device described in Japanese Patent Application Laid-Open No. 2008-297933, the fuel injection amount for the cylinder whose crankshaft speed has changed due to misfire is changed to make the crankshaft speed uniform. Therefore, the time required to rotate the predetermined crankshaft angle is also uniform, and the presence or absence of misfire may not be determined.

[0007] The present invention has been made in view of the above technical problems, and an object of the present invention is to provide a control device for an internal combustion engine that can suppress a situation where misfire cannot be determined by correcting the amount of fuel injected into the cylinders to make the combustion torque of each cylinder uniform.

[0008] In order to achieve the above-mentioned purpose, the present invention relates to a control device for an internal combustion engine, which is capable of executing ignition delay control for delaying the ignition timing for igniting the mixture in the combustion chamber compared to a predetermined normal operation, and is characterized in that the control device for the internal combustion engine includes a controller for controlling the internal combustion engine, and the controller includes: a cylinder torque calculation unit for calculating the deviation of the combustion torque of each cylinder during the execution of the ignition delay control; an injection amount correction unit for correcting the fuel injection amount to each cylinder to reduce the deviation of the combustion torque of each cylinder calculated by the cylinder torque calculation unit; and a misfire determination unit for determining misfire of the specified cylinder based on the combustion torque of the specified cylinder among the cylinders or the rotational speed of the internal combustion engine, and when the combustion torque of any cylinder among the cylinders is below a predetermined torque, the correction of the fuel injection amount to each cylinder by the injection amount correction unit is not performed.

[0009] In addition, the present invention relates to a control device for an internal combustion engine, which is capable of executing ignition delay control for delaying the ignition timing for igniting the mixture in the combustion chamber compared to a predetermined normal operation, and is characterized in that the control device for the internal combustion engine includes a controller for controlling the internal combustion engine, the controller including: a cylinder torque calculation unit for calculating a deviation of the combustion torque of each cylinder during the execution of the ignition delay control; an injection amount correction unit for correcting the fuel injection amount to each cylinder to reduce the deviation of the combustion torque of each cylinder calculated by the cylinder torque calculation unit; and a misfire determination unit for determining misfire of the specified cylinder based on the combustion torque associated with the combustion of the specified cylinder among the cylinders or the speed of the internal combustion engine and a specified determination threshold, wherein the misfire determination unit corrects the determination threshold by a change in torque or speed corresponding to the correction amount of the fuel injection amount to the specified cylinder when the fuel injection amount to each cylinder is corrected by the injection amount correction unit.

[0010] Moreover, the present invention relates to a control device for an internal combustion engine, which is capable of executing ignition delay control for delaying the ignition timing for igniting the mixture in the combustion chamber compared to a predetermined normal operation, and is characterized in that the control device for the internal combustion engine includes a controller for controlling the internal combustion engine, the controller including: a cylinder torque calculation unit for calculating a deviation amount of the combustion torque of each cylinder during the execution of the ignition delay control; an injection amount correction unit for correcting the fuel injection amount to each cylinder to reduce the deviation amount of the combustion torque of each cylinder calculated by the cylinder torque calculation unit; and a misfire determination unit for determining misfire of the specified cylinder based on the combustion torque associated with the combustion of the specified cylinder among the cylinders or the speed of the internal combustion engine and a specified determination threshold value, the misfire determination unit correcting the combustion torque or the speed by a change amount of torque or speed corresponding to the correction amount of the fuel injection amount to the specified cylinder when the fuel injection amount to each cylinder is corrected by the injection amount correction unit.

[0011] In the present invention, the control device may further include a filter that captures particulate matter contained in the exhaust gas discharged from each of the cylinders, and the controller may include an over-temperature determination unit that determines that the filter is abnormally heated when the occurrence rate of misfire determined by the misfire determination unit is greater than a predetermined ratio.

[0012] In the present invention, the overtemperature determination unit may set the predetermined ratio when the fuel injection amount to each cylinder is corrected to a value smaller than the predetermined ratio when the fuel injection amount to each cylinder is not corrected.

[0013] In the present invention, when the fuel injection amount to each cylinder is corrected, if the occurrence rate of misfire determined by the misfire determination unit is greater than a value obtained by multiplying the predetermined ratio by a coefficient smaller than 1, the overtemperature determination unit may determine that the filter is abnormally heated.

[0014] In the present invention, the over-temperature determination unit may include a three-dimensional map for determining the predetermined ratio using the rotation speed of the internal combustion engine, the load of the internal combustion engine, and the retardation amount of the ignition timing as parameters.

[0015] According to the present invention, the control device is provided with an injection amount correction unit, which corrects the fuel injection amount to each cylinder in the process of executing the ignition delay control that makes the ignition timing delayed compared with the normal operation, so as to reduce the deviation of the combustion torque of each cylinder. By correcting the fuel injection amount to each cylinder in this way, the deviation of the combustion torque in the process of executing the ignition delay control can be suppressed, so that the vibration can be suppressed. In addition, when the combustion torque of any cylinder in each cylinder is below the specified torque, the correction of the fuel injection amount by the injection amount correction unit is not performed. That is, when there is a possibility that misfire occurs in any cylinder, the correction of the fuel injection amount is not performed. In other words, the correction of the fuel injection amount is performed only when there is a possibility that misfire does not occur in all cylinders. Therefore, it is possible to suppress the situation where the judgment of the misfire of the cylinder based on the combustion torque of the cylinder and the rotation speed of the internal combustion engine cannot be performed due to the correction of the fuel injection amount.

[0016] In addition, according to the present invention, when the amount of fuel injected into each cylinder is corrected, the determination threshold for determining misfire is corrected by the correction amount of the fuel injected into the specified cylinder, or the combustion torque and speed for determining misfire are corrected by the correction amount of the fuel injected into the specified cylinder. That is, the correction of the fuel injection amount is taken into account, and the detection value and threshold for determining misfire are corrected. Therefore, it is possible to take into account both the suppression of the deviation of the combustion torque caused by the execution of the ignition delay control and the determination of misfire. That is, it is possible to determine misfire and suppress the generation of vibration caused by the deviation of the combustion torque. As a result, it is possible to promote the ignition delay control. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0018] Figure 1 This is a diagram schematically showing an example of a hybrid vehicle equipped with an internal combustion engine according to an embodiment of the present invention.

[0019] Figure 2 This is a block diagram for explaining the structure of the ECU.

[0020] Figure 3 This is a flowchart for explaining an example of fuel injection correction control.

[0021] Figure 4 This is a flowchart for explaining an example of control that enables misfire determination.

[0022] Figure 5 This is a flowchart for explaining a control example in which the misfire determination threshold is corrected to determine the presence or absence of misfire.

[0023] Figure 6 This is a flowchart for explaining a control example in which the actual combustion torque is corrected to determine the presence or absence of misfire.

[0024] Figure 7 This is a flowchart for explaining a control example of changing the OT determination threshold value according to whether or not the fuel injection correction control is executed.

[0025] Figure 8 This is a diagram showing an example of a misfire rate map.

[0026] Fig. 9 This is a flowchart for explaining a control example of setting the OT determination threshold value based on a three-dimensional map using the engine speed, the engine load, and the ignition retard amount as parameters.

[0027] Fig.10 This is a flowchart for explaining a control example of setting the OT determination threshold value according to the ignition retard amount. DETAILED DESCRIPTION

[0028] The present invention will be described based on the embodiments shown in the drawings. The embodiments described below are merely examples of the present invention, and do not limit the present invention.

[0029] Figure 1 An example of a hybrid vehicle equipped with an internal combustion engine (hereinafter referred to as an engine) according to an embodiment of the present invention is schematically shown. Figure 1 The hybrid vehicle (hereinafter, simply referred to as a vehicle) Ve shown includes an engine 1 , a first electric motor 2 , and a second electric motor 3 as drive power sources.

[0030] Figure 1 The engine 1 shown is a four-cylinder engine 1 having four cylinders #1, #2, #3, and #4. In each of the cylinders #1, #2, #3, and #4, a piston is provided in a reciprocating manner via a connecting rod (not shown) on a crankshaft 4, which is an output shaft of the engine 1, and fuel and air are supplied to a combustion chamber 5, which is a space on the upper side of the piston. Then, the crankshaft 4 is rotated by the load that presses down the piston by burning the mixture of fuel and air.

[0031] Each combustion chamber 5 is connected to an intake passage 7 via an intake manifold 6. The intake passage 7 is configured to allow external air to flow through an air filter (not shown), and a throttle valve 8 for controlling the flow rate (air volume) of the air is arranged on the upstream side. Therefore, as the opening of the throttle valve 8 increases, the amount of air flowing in the intake passage 7 increases.

[0032] The intake manifold 6 is a member for branching the air flowing in the intake passage 7 and supplying it to each cylinder #1, #2, #3, and #4, and is connected to the downstream side of the intake passage 7. Port injection valves 9 for injecting fuel toward intake ports provided in each cylinder #1, #2, #3, and #4 are provided in the branched flow passages of the intake manifold 6, respectively.

[0033] exist Figure 1 Each cylinder #1, #2, #3, and #4 shown in the figure has two intake ports and exhaust ports, and is provided with an intake valve 10 for opening and closing the intake port and an exhaust valve 11 for opening and closing the exhaust port. These intake valves 10 and exhaust valves 11 are configured to be opened and closed by a camshaft 12 that rotates synchronously with the crankshaft 4 via a timing belt (not shown) or the like.

[0034] In addition, each cylinder #1, #2, #3, and #4 is provided with an in-cylinder injection valve 15 for injecting fuel into the combustion chamber 5 and a spark plug 16 for igniting the air-fuel mixture in the combustion chamber 5. Therefore, when the intake valve 10 is opened, air and the fuel injected from the port injection valve 9 are supplied into the combustion chamber 5, and further, fuel is injected from the in-cylinder injection valve 15, thereby forming an air-fuel mixture in the combustion chamber 5. The air-fuel mixture is ignited by the spark plug 16 and burns, thereby generating a load that presses down the piston.

[0035] An exhaust passage 17 for discharging exhaust gas generated by burning the mixed gas as described above is connected to each cylinder #1, #2, #3, and #4 via an exhaust manifold 18. In the exhaust passage 17, a three-way catalyst (hereinafter referred to as a catalyst device) 19 for oxidizing and reducing hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas to purify the exhaust gas, and a gasoline particulate filter (hereinafter referred to as a GPF) 20 for capturing particulate matter (hereinafter referred to as PM) contained in the exhaust gas are arranged in order from the upstream side.

[0036] The crankshaft 4 is connected to a power distribution mechanism 21. The power distribution mechanism 21 may be composed of a single pinion type planetary gear mechanism. The crankshaft 4 is connected to the wheel carrier C of the power distribution mechanism 21. The first motor 2 is connected to the sun gear S. The ring gear R is connected to the drive wheel 22 via a gear transmission part not shown. In addition, the second motor 3 is connected to the gear transmission part between the ring gear R and the drive wheel 22.

[0037] Therefore, the output torque of the engine 1 is distributed and transmitted to the first motor 2 and the drive wheels 22 according to the gear ratio of the power split mechanism 21. By outputting torque from the second motor 3, the output torque of the second motor 3 can be added to the torque transmitted to the drive wheels 22.

[0038] Each of the above-mentioned motors 2 and 3 can be configured in the same manner as the motors provided as the driving force source of the conventional battery electric vehicle and hybrid electric vehicle. That is, in addition to the function of a motor that outputs a driving torque by being supplied with electric power, it also has the function of a generator that converts a part of its power into electric power by rotating the output shaft. As such motors 2 and 3, for example, permanent magnet synchronous motors and induction motors can be used.

[0039] Therefore, a power storage device 23 as a power source for the motors 2 and 3, and a first inverter 24 and a second inverter 25 are provided. The first inverter 24 and the second inverter 25 are configured to convert the DC power output from the power storage device 23 into AC power and output it to the motors 2 and 3, and to convert the AC power generated by the motors 2 and 3 into DC power and output it to the power storage device 23.

[0040] In addition, Figure 1 The vehicle Ve shown is provided with an electronic control unit (hereinafter referred to as ECU) 26 for controlling the throttle valve 8, the spark plug 16, the port injection valve 9, the in-cylinder injection valve 15, and each inverter 24, 25. The ECU 26 is mainly composed of a microcomputer, similar to the ECU provided in the conventional vehicle. The ECU 26 is configured to determine the amount of fuel injection to the engine 1, the ignition timing for igniting the mixture, the output torque and rotation speed of the first motor 2 and the second motor 3, etc. based on the input signal and the pre-stored map, calculation formula, etc., and output the signal to the throttle valve 8, the spark plug 16, the port injection valve 9, the in-cylinder injection valve 15, and each inverter 24, 25. In addition, the ECU 26 may also be equivalent to the "controller" in the embodiment of the present invention. The ECU 26 is not limited to a single ECU, and may also be configured to include an engine ECU for controlling the engine 1 and a motor ECU for controlling each motor 2, 3, and to communicate between these ECUs to determine each output signal.

[0041] Sensors that input signals to ECU26 include, for example, an air flow meter 27 that detects the amount of air flowing in the intake passage 7, a water temperature sensor 28 that detects the engine water temperature, a crank angle sensor 29 that detects the rotation angle (crank angle) of the crankshaft 4, a first rotary transformer 30 that detects the rotation speed of the first motor 2, and a second rotary transformer 31 that detects the rotation speed of the second motor 3.

[0042] Figure 2A block diagram for explaining the structure of the ECU 26 is shown. Figure 2 The ECU 26 shown has a cylinder torque calculation unit 32, an injection amount correction unit 33, a misfire determination unit 34, and an over-temperature determination unit 35. The cylinder torque calculation unit 32 calculates the deviation of the output torque (combustion torque) of each cylinder #1, #2, #3, and #4. For example, the combustion torque generated by the combustion of the mixture in the first cylinder #1 is calculated based on the torque acting on the first motor 2 at that time point. Specifically, the combustion torque of the first cylinder #1 is calculated based on the reaction torque based on the command value for the first motor 2, the rate of change of the rotation speed of the first motor 2 multiplied by the inertia torque of the first motor 2, the gear ratio of the power distribution mechanism 21, and the inertia torque of the engine 1. Similarly, the combustion torques of the second cylinder #2, the third cylinder #3, and the fourth cylinder #4 are calculated. Then, the difference between the average value (average torque) of the combustion torques of the cylinders #1, #2, #3, and #4 and the combustion torques of the individual cylinders #1, #2, #3, and #4 is calculated as a deviation.

[0043] The injection amount correction unit 33 corrects the amount of fuel injected into each cylinder #1, #2, #3, and #4 so as to reduce the deviation of the combustion torque calculated by the cylinder torque calculation unit 32. For example, when the combustion torque of the first cylinder #1 is higher than the average torque, the amount of fuel injected into the first cylinder #1 is reduced according to the torque difference. When the combustion torque of the first cylinder #1 is lower than the average torque, the amount of fuel injected into the first cylinder #1 is increased according to the torque difference.

[0044] The misfire determination unit 34 determines whether a misfire has occurred in each cylinder #1, #2, #3, #4. For example, the combustion torque generated by burning the mixture in the specified cylinder #1 (#2, #3, #4) as the determination object is always calculated based on the torque acting on the first motor 2 at that time point. And, in a case where the difference between the combustion torque at the time of determination and the past combustion torque of the specified cylinder #1 (#2, #3, #4) is greater than a specified difference, it is determined that a misfire has occurred in the specified cylinder #1 (#2, #3, #4). Alternatively, in a case where the difference between the combustion torque at the time of determination and the average value of the combustion torque of the specified cylinder #1 (#2, #3, #4) a specified number of times in the past is greater than a specified difference, it is determined that a misfire has occurred in the specified cylinder #1 (#2, #3, #4). Alternatively, in order to determine a complete misfire situation such as a specified cylinder #1 (#2, #3, #4) failing to ignite, when the difference between the combustion torque of the specified cylinder #1 (#2, #3, #4) and the combustion torque of other cylinders #2 (#1, #3, #4) is greater than a specified difference, it is determined that a misfire has occurred in the specified cylinder #1 (#2, #3, #4).

[0045] That is, the misfire judgment unit 34 uses the past combustion torque, the average value of the past combustion torque, or the combustion torque #2 (#1, #3, #4) of other cylinders as the specified judgment threshold, and judges the misfire of the specified cylinder #1 (#2, #3, #4) based on the combustion torque at the time of judgment of the specified cylinder #1 (#2, #3, #4) and the specified judgment threshold.

[0046] In addition, the misfire determination unit 34 may determine that a misfire has occurred by comparing the rotational variation of the crankshaft 4 (i.e., the rotation speed of the engine 1) at the time of misfire determination with the rotational variation before the rotation angle (crankshaft angle) of the crankshaft 4 is 720°CA, similarly to the control device described in Japanese Patent Application Laid-Open No. 2022-062848. In this case, the rotational variation before 720°CA becomes the "predetermined determination threshold" in the embodiment of the present invention.

[0047] The over-temperature determination unit 35 determines whether the temperature of the GPF 20 is equal to or higher than the permissible upper limit temperature. Specifically, when the occurrence rate (number of occurrences) of misfires of the engine 1 is equal to or higher than a predetermined ratio (predetermined number of times) predetermined according to the operating state of the engine 1, it is determined that the temperature of the GPF 20 is equal to or higher than the permissible upper limit temperature.

[0048] The engine 1 constructed as described above is capable of performing a catalyst preheating control for heating the catalyst device 19 to an activation temperature. The catalyst preheating control is a control performed when the bed temperature of the catalyst device 19 is below a predetermined specified temperature (activation temperature). The catalyst preheating control includes an HV catalyst preheating control that delays the ignition timing compared to the normal operation in which the catalyst device 19 is heated to the activation temperature. The catalyst preheating control includes a rapid catalyst preheating control in which the delay amount of the ignition timing is made larger than the delay amount of the ignition timing of the HV catalyst preheating control, and stratified injection combustion is performed by injecting fuel from the in-cylinder injection valve 15 into the combustion chamber 5 in the late stage of the compression stroke so that the state near the spark plug 16 is an over-rich state at the ignition timing. In addition, compared with the HV catalyst preheating control, the rapid catalyst preheating control can accelerate the heating rate of the catalyst device 19.

[0049] In addition, when the amount of PM accumulated on the GPF 20 reaches a predetermined amount or more, a GPF regeneration control can be performed to restore the trapping function of the GPF 20. The GPF regeneration control is a control to burn and remove the PM accumulated on the GPF 20 by supplying air containing oxygen to the GPF 20. Specifically, the GPF regeneration control delays the ignition timing compared to the case where the GPF regeneration control is not performed.

[0050] In the above-mentioned warm-up control and GPF regeneration control, as the ignition timing is retarded, the combustion in each cylinder #1, #2, #3, #4 becomes unstable. That is, the combustion torque generated in each cylinder #1, #2, #3, #4 is deviated, and the engine 1 may excessively vibrate. Therefore, the control device in the embodiment of the present invention is configured to correct the amount of fuel injected into each cylinder #1, #2, #3, #4 to suppress the deviation of the combustion torque generated in each cylinder #1, #2, #3, #4 when the ignition delay control for retarding the ignition timing is executed.

[0051] Figure 3 1 is a flowchart for explaining a control example for suppressing the deviation of the combustion torque caused by executing the ignition delay control. Figure 3 In the control example shown, first, it is determined whether the conditions for executing the ignition delay control are met (S1). Specifically, it is determined whether there is a request to execute the HV catalyst warm-up control or the rapid catalyst warm-up control, or it is determined whether there is a request to execute the GPF regeneration control. That is, it is determined whether the catalyst bed temperature is lower than the predetermined activation temperature, and whether the pressure on the upstream side of the GPF 20 is higher than the pressure on the downstream side by a predetermined pressure or more.

[0052] If a negative determination is made in S1 because the conditions for executing the ignition delay control are not satisfied, the routine is immediately terminated temporarily. On the contrary, if an affirmative determination is made in S1 because the conditions for executing the ignition delay control are satisfied, the ignition delay control is executed (S2).

[0053] Next, it is determined whether the prerequisite for the fuel injection amount correction control is established (S3). This S3 is a step for determining whether the combustion torque can be detected to obtain the deviation of the combustion torque. In the control example shown here, the combustion torque of each cylinder #1, #2, #3, and #4 is detected by the first motor 2. Therefore, in S3, for example, it is determined whether the system such as the first motor 2 and the rotary transformer 30 for detecting its rotation speed are functioning normally.

[0054] In the case where a negative judgment is made in S3 because the prerequisite for the fuel injection amount correction control is not satisfied, the routine is directly temporarily terminated. On the contrary, in the case where an affirmative judgment is made in S3 because the prerequisite for the fuel injection amount correction control is satisfied, the correction amount of the fuel injection amount to each cylinder #1, #2, #3, and #4 is calculated (S4). Specifically, first, the combustion torque of each cylinder #1, #2, #3, and #4 is calculated in sequence based on the torque acting on the first motor 2 by the cylinder torque calculation unit 32, and the average torque of the calculated combustion torque is calculated. Next, the difference between the combustion torque of each cylinder #1, #2, #3, and #4 and the average torque is calculated to calculate the deviation. That is, the correction torque required to reduce the deviation is calculated for each cylinder #1, #2, #3, and #4. Then, the correction amount of the fuel injection amount is calculated by multiplying the correction torque by a specified coefficient that relates the fuel amount to the torque. Furthermore, when the difference between the combustion torque and the average torque is equal to or smaller than a predetermined difference such as a slight difference that does not affect the vibration of the vehicle, the correction torque may be set to “0”.

[0055] Next, the fuel injection correction control (S5) is performed on each cylinder #1, #2, #3, and #4. That is, for the cylinder whose combustion torque is less than the average torque, the fuel injection amount is increased, and for the cylinder whose combustion torque is greater than the average torque, the fuel injection amount is reduced. Then, in this control example, the delay amount of the ignition timing is further increased (S6), and the routine is temporarily terminated. The purpose of this S6 is to reduce the deviation of the combustion torque by correcting the fuel injection amount as described above, thereby further increasing the heating rate of the catalyst device 19, or quickly regenerating the GPF 20. Therefore, the additional delay amount is determined so that the deviation of the fuel torque is within the allowable range. In addition, the step of further delaying the ignition timing based on S6 may not be performed.

[0056] When the ignition delay control is performed in this way, by performing the fuel injection correction control, even if the combustion becomes unstable due to the ignition delay control, the fuel injection amount to each cylinder #1, #2, #3, #4 can be corrected. Therefore, the deviation of the combustion torque can be reduced. In other words, the vibration of the vehicle caused by the deviation of the combustion torque can be suppressed. In addition, compared with the case where the fuel injection amount to each cylinder #1, #2, #3, #4 is not corrected in this way, the delay amount of the ignition timing can be increased, so the catalyst device 19 can be quickly heated up, or the GPF 20 can be quickly regenerated.

[0057] On the other hand, as described above, the misfire determination unit 34 determines misfire of the specified cylinder #1 (#2, #3, #4) based on the combustion torque at the time of determination of the specified cylinder #1 (#2, #3, #4), the rotational variation amount corresponding to the combustion torque, and the specified determination threshold value. Therefore, there is a possibility that misfire cannot be determined due to the correction of the fuel injection amount.

[0058] Therefore, the control device in the embodiment of the present invention is configured not to correct the fuel injection amount when misfire is likely to occur. A flowchart for explaining an example of this control is shown in FIG. Figure 4 In addition, Figure 3 The same steps as those in the control example shown are denoted by the same reference numerals and their descriptions are omitted.

[0059] exist Figure 4 In the control example shown, following S4, it is determined whether the combustion torque of any cylinder is less than a predetermined torque (S11). This S11 is a step for determining whether misfire is likely to occur in any cylinder. Therefore, the predetermined torque can be set to the magnitude of the torque generated when misfire occurs, or the magnitude of the torque slightly larger than the magnitude of the torque.

[0060] In the case where an affirmative determination is made in S11 because the combustion torque of any cylinder is below the prescribed torque, if the fuel injection amount is corrected to reduce the deviation of the combustion torque of each cylinder #1, #2, #3, and #4, misfire cannot be determined. In addition, for example, in the case where ignition cannot be performed and misfire occurs, the combustion torque of the cylinder is substantially 0. Therefore, in the case where the deviation of the combustion torque of each cylinder #1, #2, #3, and #4 is to be reduced, the fuel injection amount to the cylinder is increased. In this case, there is a possibility that the fuel becomes excessive in the combustion chamber 5, and fuel hammer (fuel hammer) occurs. Therefore, in the case where an affirmative determination is made in S11, the fuel injection correction control (S12) is not executed, and the routine is temporarily terminated.

[0061] On the contrary, when a negative determination is made in S11 because the combustion torque of all cylinders is higher than the prescribed torque, the fuel injection correction control (S5) is performed for each cylinder #1, #2, #3, and #4. That is, the fuel injection amount is increased for the cylinder whose combustion torque is lower than the average torque, and the fuel injection amount is reduced for the cylinder whose combustion torque is higher than the average torque, and the routine is temporarily terminated.

[0062] As described above, when misfire is likely to occur in any cylinder due to the combustion torque of any cylinder being below the predetermined torque, the fuel injection correction control is prohibited. In other words, the combustion injection correction control is performed only when there is no possibility of misfire. That is, the determination of the presence or absence of misfire is prioritized over suppressing the deviation of the combustion torque. As a result, it is possible to suppress the situation where the presence or absence of misfire cannot be determined by executing the fuel injection correction control.

[0063] Figure 5 and Figure 6 A flowchart for explaining a control example that can achieve both correction of the fuel injection amount for suppressing the deviation of the combustion torque and determination of misfire. Figure 5 The control example shown is configured to determine the presence or absence of misfire by correcting the determination threshold for determining the presence or absence of misfire, and comparing the combustion torque after the fuel injection amount is corrected and the rotation variation of the crankshaft 4 with the corrected determination threshold to determine the presence or absence of misfire. Figure 3 and Figure 4 The same steps as those in the control example shown are denoted by the same reference numerals and their descriptions are omitted.

[0064] exist Figure 5 In the control example shown, after the fuel injection correction control is executed by S5, the judgment threshold (S21) for judging the presence or absence of misfire is corrected by the misfire judgment unit 34. That is, when the misfire judgment unit 34 compares the combustion torque at the time point of executing the routine with the past combustion torque to judge the presence or absence of misfire, the past combustion torque is corrected. Specifically, when the fuel injection amount of the specified cylinder #1 (#2, #3, #4) is increased, the torque increased by increasing the fuel injection amount is added to the past combustion torque before the fuel injection amount is corrected. On the contrary, when the fuel injection amount of the specified cylinder #1 (#2, #3, #4) is reduced, the torque reduced by reducing the fuel injection amount is subtracted from the past combustion torque before the fuel injection amount is corrected. In addition, by multiplying the correction amount of the fuel injection amount by a predetermined coefficient, etc., the increase or decrease amount of the combustion torque caused by the correction of the fuel injection amount can be calculated.

[0065] Similarly, when the misfire determination unit 34 compares the combustion torque at the time when the routine is executed with the average value of the past combustion torque before the fuel injection amount is corrected to determine the presence of misfire, the average value of the past combustion torque before the fuel injection amount is corrected. In addition, when the misfire determination unit 34 compares the combustion torque at the time when the routine is executed with the combustion torque of other cylinders to determine the presence of misfire, the combustion torque of other cylinders is corrected.

[0066] Furthermore, when the misfire determination unit 34 determines that a misfire has occurred by comparing the rotational variation of the crankshaft 4 at the time of misfire determination with the rotational variation before the crankshaft angle reaches a predetermined angle, the rotational variation before the predetermined angle is corrected. Specifically, first, the increase or decrease in the combustion torque caused by the correction of the fuel injection amount is obtained by multiplying the correction of the fuel injection amount by a predetermined coefficient, etc. The rotational variation of the crankshaft 4 increases or decreases according to the combustion torque, and therefore, the change in the rotational variation caused by the correction of the fuel injection amount is obtained by multiplying the increase or decrease in the combustion torque caused by the correction of the fuel injection amount by a predetermined coefficient, etc. Then, the change in the rotational variation obtained is added or subtracted from the rotational variation before the predetermined angle.

[0067] On the other hand, when a negative judgment is made in S3 because the precondition is not satisfied, the fuel injection correction control (S12) is not executed. Therefore, the determination threshold (S22) for determining the presence or absence of misfire by the misfire determination unit 34 is not corrected. That is, when misfire is determined based on the past combustion torque before the fuel injection amount is corrected, its average value, or the combustion torque of other cylinders, or the rotational variation of the crankshaft 4, the rotational variation before the predetermined angle is set as the determination threshold.

[0068] Following S21 and S22, it is determined whether the prerequisite for misfire determination is satisfied (S23). This S23 determines, for example, whether the rotation speed of the crankshaft 4 is above a predetermined rotation speed after the engine is started, that is, whether the number of samples of the past combustion torque is above a predetermined number, or whether the change of the fuel injection amount corresponding to the correction amount based on the fuel injection control is completed.

[0069] If the precondition for misfire determination is not satisfied and the determination in S23 is negative, the routine is terminated immediately. On the contrary, if the precondition for misfire determination is satisfied and the determination in S23 is positive, the misfire determination process is executed (S24).

[0070] In this control example, the misfire determination unit 34 compares the combustion torque at the time point when the routine is executed with the past combustion torque to determine whether there is a misfire. Therefore, when the misfire determination process is executed, the combustion torque generated by injecting the fuel injection amount corrected by S4 is detected, and it is determined whether the detected actual combustion torque is below the determination threshold (S25). That is, when the determination threshold is corrected in S21, it is determined whether the actual combustion torque is below the corrected determination threshold. When S22 is executed and the determination threshold is not corrected, it is determined whether the actual combustion torque is below the past combustion torque before the fuel injection amount is corrected.

[0071] Then, if an affirmative determination is made in S25 because the actual combustion torque is below the determination threshold, it is determined that a misfire abnormality has occurred (S26). On the contrary, if a negative determination is made in S25 because the actual combustion torque is a torque higher than the determination threshold, it is determined that no misfire abnormality has occurred, that is, it is normal (S27), and the routine is temporarily terminated.

[0072] In the above control example, the fuel injection amount is corrected to suppress the deviation of the combustion torque. And the presence or absence of misfire is determined by comparing the actual combustion torque (actual rotational variation) generated by injecting the corrected fuel injection amount with the judgment threshold value obtained by correcting the amount corresponding to the combustion torque (or rotational variation) that changes due to the correction of the fuel injection amount. Therefore, it is possible to take into account both the suppression of the deviation of the combustion torque caused by the execution of the ignition delay control and the judgment of the misfire. That is, it is possible to suppress the generation of vibration caused by the deviation of the combustion torque while making a judgment of the misfire. As a result, the ignition delay control can be promoted, the catalyst device 19 can be activated quickly, and the GPF 20 can be regenerated quickly.

[0073] Figure 6 The control example shown is configured to obtain a virtual combustion torque obtained by adding and subtracting the change in the combustion torque caused by the correction of the fuel injection amount from the actual combustion torque after the fuel injection amount is corrected. Then, the virtual combustion torque is compared with the determination threshold for determining the presence or absence of misfire to determine the presence or absence of misfire. Figures 3 to 5 The same steps as those in the control example shown are denoted by the same reference numerals and their descriptions are omitted.

[0074] exist Figure 6 In the control example shown, following S5, a hypothetical combustion torque (S31) is calculated. In this S31, the combustion torque generated when the fuel injection amount is not corrected is calculated as the hypothetical combustion torque. Therefore, in S31, the combustion torque after the fuel injection amount is corrected is detected, and the increase or decrease in the combustion torque caused by the correction of the fuel injection amount is added or subtracted from the detected actual combustion torque. Specifically, when the fuel injection amount is increased by S5, the torque increased by increasing the fuel injection amount is subtracted from the actual combustion torque. On the contrary, when the fuel injection amount is reduced by S5, the torque reduced by reducing the fuel injection amount is added to the actual combustion torque.

[0075] In addition, when the misfire determination unit 34 determines misfire based on the rotational variation of the crankshaft 4, it is sufficient to detect the actual rotational variation of the crankshaft 4 after the fuel injection amount is corrected, and add or subtract the increase or decrease amount of the rotational variation caused by the correction of the fuel injection amount from the detected actual rotational variation. The increase or decrease amount of the rotational variation caused by the correction of the fuel injection amount can be obtained based on the increase or decrease amount of the combustion torque caused by the correction of the fuel injection amount as described above.

[0076] And, in Figure 6 In the control example shown, when the misfire determination process is executed in S24, the misfire determination unit 34 determines whether the hypothetical combustion torque calculated in S31 is below a determination threshold such as the past combustion torque before the fuel injection amount is corrected, its average value, or the combustion torque of other cylinders (S32).

[0077] Then, if an affirmative determination is made in S32 because the assumed combustion torque is below the determination threshold, it is determined that a misfire abnormality has occurred (S26). On the contrary, if a negative determination is made in S32 because the assumed combustion torque is a torque higher than the determination threshold, it is determined that no misfire abnormality has occurred, that is, it is normal (S27), and the routine is temporarily terminated.

[0078] In the above control example, the fuel injection amount is corrected to suppress the deviation of the combustion torque. From the actual combustion torque (actual rotational variation) generated by injecting the corrected fuel injection amount, an amount corresponding to the combustion torque (or rotational variation) that changes due to the correction of the fuel injection amount is added or subtracted to obtain a hypothetical combustion torque, and the hypothetical combustion torque is compared with the judgment threshold to determine whether misfire occurs. Therefore, it is possible to take into account both suppressing the deviation of the combustion torque caused by executing the ignition delay control and determining the misfire. That is, it is possible to suppress the generation of vibrations caused by the deviation of the combustion torque while making a determination of misfire. As a result, the ignition delay control can be promoted, the catalyst device 19 can be activated quickly, and the GPF 20 can be regenerated quickly.

[0079] As described above, by executing the fuel injection correction control, the retardation amount of the ignition timing can be increased, so that the GPF 20 can be quickly regenerated. On the other hand, the temperature rise amount of the GPF 20 accompanying the occurrence of misfire is faster than the case where the normal ignition delay control without executing the fuel injection control is executed. That is, the occurrence frequency (number of occurrences) of misfires reaching the upper limit temperature determined to protect the GPF 20 is reduced. Therefore, the control device in the embodiment of the present invention is configured to change the threshold value for judging the abnormal heating of the GPF 20 according to the presence or absence of the execution of the fuel injection correction control.

[0080] Figure 7 , Fig. 9 and Fig.10 A flowchart for explaining the control example is shown. Figures 4 to 6 The control example is executed. Figure 7 The control example shown is configured to change the threshold value for determining abnormal heating of the GPF 20 according to whether the fuel injection correction control is executed. Therefore, first, it is determined whether the fuel injection correction control is executed (S41). In this S41, by determining whether the fuel injection correction control is executed, it is determined whether the ignition delay amount is increased compared to the ignition delay amount when the fuel injection correction control is not executed. In addition, it is possible to make a determination based on whether the above-mentioned S5 is executed.

[0081] In the case where a negative determination is made in S41 because the fuel injection correction control is not executed, a predetermined normal determination value is set as a threshold value for determination of abnormal heating (OT determination threshold value) (S42). As described above, the temperature of the GPF 20 increases according to the degree of occurrence of misfire, so the misfire rate (OT misfire rate) can be used as a threshold value for determination of abnormal heating. An example of this OT misfire rate is shown as a map in Figure 8 . Figure 8 The OT misfire rate map shown is a map obtained by determining the occurrence rate of misfire caused by abnormal heating of the GPF 20 in advance through experiments, etc., using the engine speed and engine load as parameters. The OT misfire rate map is stored in the ECU 26 (overtemperature determination unit 35). Figure 8 As shown in FIG. 1 , the OT misfire rate map is configured such that the OT misfire rate (i.e., the normal judgment value) is set larger as the engine speed is lower, and the OT misfire rate (i.e., the normal judgment value) is set larger as the engine load is smaller. In addition, the so-called misfire occurrence rate is the ratio of the number of occurrences of misfires in the engine 1 to the predetermined number of combustions (i.e., equivalent to the engine speed) (number of occurrences of misfires / predetermined number of combustions). That is, the number of occurrences of misfires is calculated by accumulating the misfires that occur in each cylinder #1, #2, #3, and #4, thereby calculating the occurrence rate of misfires.

[0082] Therefore, in S42, the OT determination threshold is determined by detecting the engine speed and the engine load and referring to the OT misfire rate map. In addition, the occurrence rate of misfire is the number of misfires in a predetermined number of combustions, so the occurrence rate of misfire is substantially synonymous with the number of misfires.

[0083] On the contrary, when a positive determination is made in S41 due to the execution of the fuel injection correction control, a correction determination value is set as the OT determination threshold value (S43), and the correction determination value is determined so that the occurrence rate of misfire is lower than the above-mentioned normal determination value. In S43, the misfire occurrence rate at which the GPF 20 becomes abnormally heated when the engine 1 is operated with the ignition retard amount that can be set when the fuel injection correction control is executed is obtained through experiments, etc. The misfire occurrence rate can be mapped and stored in the ECU 26, so that the correction determination value can be obtained. In addition, in this case, even if the engine speed and the engine load are the same as in normal times, the GPF 20 becomes abnormally heated with a lower misfire occurrence rate.

[0084] Following S42 and S43, it is determined whether the misfire rate is equal to or higher than the OT determination threshold (S44). Figures 4 to 6 When misfire abnormality determination is performed according to the control example shown in FIG. 1 , the history is stored, and the misfire occurrence rate at a predetermined number of combustions is calculated. Then, in S44, the misfire occurrence rate is compared with the OT determination threshold value.

[0085] When a positive determination is made in S44 because the misfire occurrence rate is greater than the OT determination threshold, an OT abnormal determination is performed (S45). On the contrary, when a negative determination is made in S44 because the misfire occurrence rate is less than the OT determination threshold, a normal determination is performed (S46), and the routine is temporarily terminated. In addition, when an OT abnormal determination is made in S45, for example, a display indicating that the GPF 20 is abnormally heated is made on the instrument panel to warn the driver, or control to limit the output of the engine 1 to suppress further temperature rise of the GPF 20 may be performed.

[0086] When the fuel injection correction control is performed as described above and the ignition delay amount is increased, by changing the OT judgment threshold to a misfire incidence rate that is less than the ignition delay amount in the normal ignition delay control, the abnormal heating of GPF20 can be suppressed or the abnormal heating of GPF20 can be accurately judged.

[0087] Fig. 9 The control example shown is similar to Figure 7 The control examples shown are different only in the method of setting the OT determination threshold. Fig. 9 In the control example shown, after setting the OT determination threshold (S51) with reference to the OT misfire rate map (three-dimensional map) that uses the ignition delay amount as a parameter in addition to the engine speed and the engine load, the above-mentioned processing after S44 is executed. The OT misfire rate map can be determined so that the OT determination threshold (misfire occurrence rate) becomes smaller as the ignition delay amount becomes larger.

[0088] By determining the OT determination threshold value based on the OT misfire rate map using the ignition delay amount as a parameter as described above, even when the ignition delay amount is arbitrarily changed, the OT determination threshold value corresponding to the ignition delay amount can be set. As a result, the occurrence of abnormal heating of the GPF 20 can be suppressed, or the abnormal heating of the GPF 20 can be accurately determined.

[0089] Fig.10 The control example shown is similar to Figure 7 and Fig. 9 The control examples shown are different only in the method of setting the OT determination threshold. Fig.10 In the control example shown, after the OT determination threshold is set by multiplying the normal determination threshold by a predetermined coefficient determined according to the ignition delay amount (S61), the processing after S44 is executed. The predetermined coefficient is a coefficient smaller than "1" and is set to a smaller value as the ignition delay amount increases.

[0090] By multiplying the normal determination threshold by the predetermined coefficient corresponding to the ignition delay amount as described above to determine the OT determination threshold, even when the ignition delay amount is arbitrarily changed, the OT determination threshold corresponding to the ignition delay amount can be set. As a result, the occurrence of abnormal heating of the GPF 20 can be suppressed, or the abnormal heating of the GPF 20 can be accurately determined.

[0091] In addition, in the above control example, since the detection speed of the first motor 2 is fast and the detection accuracy is good, the first motor 2 is configured to calculate the combustion torque of each cylinder #1, #2, #3, and #4 from the torque acting on the first motor 2. However, the cylinder torque calculation unit in the embodiment of the present invention only needs to be able to detect the combustion torque of each cylinder #1, #2, #3, and #4, and can also be configured to detect it through other sensors. In addition, the internal combustion engine in the embodiment of the present invention is not limited to being mounted on Figure 1 The internal combustion engine of the so-called series-parallel hybrid vehicle constructed as shown can also be an internal combustion engine installed in a series hybrid vehicle, a parallel hybrid vehicle, or an internal combustion engine installed in a so-called conventional vehicle having only an engine as a driving force source.

Claims

1. A control device for an internal combustion engine capable of executing ignition delay control for delaying the ignition timing for igniting a mixture in a combustion chamber from a predetermined normal operation, characterized in that: The control device for the internal combustion engine includes a controller for controlling the internal combustion engine. The controller has: According to the cylinder torque calculation unit, during the execution of the ignition delay control, a deviation amount of the combustion torque of each cylinder is obtained; an injection amount correction unit that corrects the fuel injection amount to each of the cylinders so as to reduce a deviation of the combustion torque of each of the cylinders obtained by the cylinder-specific torque calculation unit; and a misfire determination unit that determines misfire of a predetermined cylinder among the cylinders based on the combustion torque of the predetermined cylinder or the rotation speed of the internal combustion engine, When the combustion torque of any one of the cylinders is equal to or less than a predetermined torque, the injection amount correction unit does not correct the fuel injection amount to each of the cylinders.

2. A control device for an internal combustion engine capable of executing ignition delay control for delaying the ignition timing for igniting a mixture in a combustion chamber from a predetermined normal operation, characterized in that: The control device for the internal combustion engine includes a controller for controlling the internal combustion engine. The controller has: According to the cylinder torque calculation unit, during the execution of the ignition delay control, a deviation amount of the combustion torque of each cylinder is obtained; an injection amount correction unit that corrects the fuel injection amount to each of the cylinders so as to reduce a deviation of the combustion torque of each of the cylinders obtained by the cylinder-specific torque calculation unit; and a misfire determination unit that determines misfire in a predetermined cylinder among the cylinders based on a combustion torque associated with combustion in the predetermined cylinder or a rotation speed of the internal combustion engine and a predetermined determination threshold value, The misfire determination unit corrects the determination threshold value by an amount of change in torque or rotation speed corresponding to an amount of correction of the fuel injection amount to the predetermined cylinder when the injection amount correction unit corrects the fuel injection amount to each of the cylinders.

3. A control device for an internal combustion engine capable of executing ignition delay control for delaying the ignition timing for igniting a mixture in a combustion chamber from a predetermined normal operation, characterized in that: The control device for the internal combustion engine includes a controller for controlling the internal combustion engine. The controller has: According to the cylinder torque calculation unit, during the execution of the ignition delay control, a deviation amount of the combustion torque of each cylinder is obtained; an injection amount correction unit that corrects the fuel injection amount to each of the cylinders so as to reduce a deviation of the combustion torque of each of the cylinders obtained by the cylinder-specific torque calculation unit; and a misfire determination unit that determines misfire in a predetermined cylinder among the cylinders based on a combustion torque associated with combustion in the predetermined cylinder or a rotation speed of the internal combustion engine and a predetermined determination threshold value, The misfire determination unit corrects the combustion torque or the rotation speed by a change amount of the torque or the rotation speed corresponding to the correction amount of the fuel injection amount to the predetermined cylinder when the injection amount correction unit corrects the fuel injection amount to each cylinder.

4. The control device for an internal combustion engine according to claim 2 or 3, characterized in that: The control device for the internal combustion engine further includes a filter for collecting particulate matter contained in the exhaust gas discharged from each of the cylinders. The controller includes an overtemperature determination unit configured to determine that the filter is abnormally heated when the occurrence rate of misfire determined by the misfire determination unit is equal to or higher than a predetermined ratio.

5. The control device for an internal combustion engine according to claim 4, characterized in that: The overtemperature determination unit sets the predetermined ratio when the fuel injection amount to each cylinder is corrected to a value smaller than the predetermined ratio when the fuel injection amount to each cylinder is not corrected.

6. The control device for an internal combustion engine according to claim 4, characterized in that: When the occurrence rate of misfire determined by the misfire determination unit is equal to or higher than a value obtained by multiplying the predetermined ratio by a coefficient smaller than 1 when the fuel injection amount to each cylinder is corrected, the overtemperature determination unit determines that the filter is abnormally heated.

7. The control device for an internal combustion engine according to claim 4, characterized in that: The over-temperature determination unit includes a three-dimensional map for determining the predetermined ratio using the rotation speed of the internal combustion engine, the load of the internal combustion engine, and the retardation amount of the ignition timing as parameters.

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