JP6604259B2 - Control device for internal combustion engine - Google Patents

Description

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

  For example, Patent Document 1 discloses a control device for an internal combustion engine including an in-cylinder pressure sensor. This control device uses the output value of the in-cylinder pressure sensor to perform feedback control of the fuel injection amount so that the actual crank angle period from the ignition timing to the crank angle at which a predetermined combustion mass ratio is obtained approaches the target crank angle period. Is executed. Further, in this control device, feedback control of ignition timing is performed using the output value of the in-cylinder pressure sensor so that the actual combustion center of gravity (crank angle CA50 when the combustion mass ratio becomes 50%) approaches the target combustion center of gravity. Executed. In addition, the two feedback controls are configured such that the response speed for adjusting the ignition timing is higher than the response speed for adjusting the fuel injection amount.

Japanese Patent Laying-Open No. 2015-094339 Japanese Patent Laid-Open No. 9-273468

  As described above, the feedback control described in Patent Document 1 is configured such that the response speed for adjusting the ignition timing is higher than the response speed for adjusting the fuel injection amount. Here, during the transient operation of the internal combustion engine, the actual air-fuel ratio tends to deviate from the target air-fuel ratio due to a delay in transportation of the air amount. According to the configuration of Patent Literature 1, during the transient operation, first, the ignition timing is quickly adjusted so as to reduce the deviation of the actual combustion gravity center from the target combustion gravity center caused by the air-fuel ratio deviation. When the actual crank angle period follows the target crank angle period by adjusting the fuel injection amount at a timing delayed from the adjustment of the ignition timing, a deviation of the actual combustion center of gravity due to the adjustment of the fuel injection amount occurs. End up. In the ignition timing feedback control, the ignition timing is adjusted again to reduce the deviation. Further, the feedback control of the fuel injection amount adjusts the fuel injection amount in response to a change in the actual crank angle period resulting from the adjustment of the ignition timing.

  In the case where the configuration of Patent Document 1 is provided, as a result of the above-described operation, the control amount of the above-described feedback control (actual combustion center of gravity and Overshoot with respect to the target value of the (angular period) is likely to occur. As a result, exhaust emission and drivability of the internal combustion engine may be deteriorated. In addition, feedback control potentially involves a response delay regardless of the configuration. For this reason, during transient operation, exhaust emission and drivability of the internal combustion engine may be deteriorated due to the fact that the air-fuel ratio deviation cannot be corrected due to a delay in feedback control response.

  The present invention has been made in order to solve the above-described problems. The feedback control of the fuel injection amount using the ignition delay index value based on the output value of the in-cylinder pressure sensor and the combustion timing index based on the output value are provided. Control device for an internal combustion engine capable of suppressing deterioration of exhaust emission and drivability due to deviation of the actual air-fuel ratio with respect to the target air-fuel ratio during transient operation in a configuration in which feedback control of ignition timing using values is executed The purpose is to provide.

  An internal combustion engine control apparatus according to an aspect of the present invention includes an ignition device that ignites an air-fuel mixture in a cylinder, a fuel injection valve that supplies fuel into the cylinder, and an in-cylinder pressure sensor that detects in-cylinder pressure. Control the internal combustion engine. The control device includes index value calculation means, first feedback control means, and second feedback control means. The index value calculation means calculates an actual ignition delay index value and an actual combustion timing index value based on the output value of the in-cylinder pressure sensor. The first feedback control means executes feedback control of the fuel injection amount so that the actual ignition delay index value approaches the target ignition delay index value. The second feedback control means executes feedback control of ignition timing so that the actual combustion timing index value approaches the target combustion timing index value. In the transient operation of the internal combustion engine, the first feedback control means and the second feedback control means are configured such that a response speed of adjustment of the fuel injection amount by the first feedback control means is the second feedback control means. It is configured to be higher than the response speed of the adjustment of the ignition timing by.

An internal combustion engine control apparatus according to another aspect of the present invention includes an ignition device that ignites an air-fuel mixture in a cylinder, a fuel injection valve that supplies fuel into the cylinder, and an in-cylinder pressure sensor that detects in-cylinder pressure. The internal combustion engine provided is controlled. The control device includes index value calculation means, first feedback control means, second feedback control means, and transient adjustment means. The index value calculation means calculates an actual ignition delay index value and an actual combustion timing index value based on the output value of the in-cylinder pressure sensor. The first feedback control means executes feedback control of the fuel injection amount so that the actual ignition delay index value approaches the target ignition delay index value. The second feedback control means executes feedback control of ignition timing so that the actual combustion timing index value approaches the target combustion timing index value. The transient adjustment means, instead of adjusting the fuel injection amount by the first feedback control means, during the transient operation of the internal combustion engine, the time rate of change of the engine load factor and the injection amount increase value based on the engine load factor The adjustment of the fuel injection amount using is performed. The injection amount increase value is an increase value with respect to the basic fuel injection amount. During steady operation of the internal combustion engine, the feedback control of the fuel injection amount by the first feedback control means and the feedback control of the ignition timing by the second feedback control means are executed. During the transient operation, of the feedback control of the fuel injection amount by the first feedback control means and the feedback control of the ignition timing by the second feedback control means, the ignition timing by the second feedback control means Only feedback control is performed. Further, the second feedback control means may retard the target combustion timing index value with respect to a value at which the MBT ignition timing is obtained during the transient operation.

  According to one aspect of the present invention, the fuel injection amount adjustment response speed by the first feedback control means is made higher than the response speed of the ignition timing adjustment by the second feedback control means, thereby causing an air-fuel ratio shift. In this case, it is possible to quickly correct the fuel injection amount, which is a parameter to be adjusted first in order to suppress the air-fuel ratio deviation. In other words, more effective correction of the fuel injection amount can be advanced in order to cope with the air-fuel ratio deviation. As a result, it is possible to reduce the amount of control of each feedback control from overshooting the target value due to the rapid adjustment of the ignition timing, contrary to such a configuration. As a result, it is possible to suppress the deterioration of exhaust emission and drivability due to the above-described air-fuel ratio shift.

  Further, according to another aspect of the present invention, during transient operation, instead of adjusting the fuel injection amount by the first feedback control means, the engine load factor time change rate and the injection amount increase value based on the engine load factor are set. Adjustment of the used fuel injection amount is executed. As a result, in a situation where an increase in the fuel injection amount is required, if the feedback control is used to adjust the fuel injection amount, the drivability that can occur due to the fact that the air-fuel ratio cannot be corrected due to the response delay Deterioration of exhaust emissions can be suppressed.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a flowchart showing the main routine of the control performed in Embodiment 1 of this invention. It is a flowchart showing the subroutine showing the process regarding SA-CA10 feedback control. It is a flowchart showing the subroutine showing the process regarding CA50 feedback control. It is a flowchart showing the main routine of the control performed in Embodiment 2 of this invention. It is a flowchart showing the main routine of the control performed in Embodiment 3 of this invention. It is an image figure for demonstrating the setting of the map referred in order to determine the injection quantity increase value in Embodiment 3 of this invention.

Embodiment 1 FIG.
First, Embodiment 1 of the present invention will be described with reference to FIGS.

[System Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes a spark ignition type internal combustion engine (a gasoline engine as an example) 10. A piston 12 is provided in the cylinder of the internal combustion engine 10. A combustion chamber 14 is formed on the top side of the piston 12 in the cylinder. An intake passage 16 and an exhaust passage 18 communicate with the combustion chamber 14.

  The intake port of the intake passage 16 is provided with an intake valve 20 that opens and closes the intake port, and the exhaust port of the exhaust passage 18 is provided with an exhaust valve 22 that opens and closes the exhaust port. The intake passage 16 is provided with an electronically controlled throttle valve 24. Each cylinder of the internal combustion engine 10 has a fuel injection valve (for example, a direct injection type fuel injection valve) 26 for supplying fuel into the combustion chamber 14 (in-cylinder), and an ignition for igniting an air-fuel mixture. A device (only the spark plug is shown) 28 is provided. Furthermore, an in-cylinder pressure sensor 30 for detecting the in-cylinder pressure is incorporated in each cylinder.

  Furthermore, the system of the present embodiment includes a drive circuit (not shown) for driving the following various actuators as well as an electronic control unit (ECU) 40 as a control device for controlling the internal combustion engine 10. In addition to the in-cylinder pressure sensor 30 described above, the ECU 40 receives signals from a crank angle sensor 42 disposed near the crankshaft (not shown) and an airflow sensor 44 disposed near the inlet of the intake passage 16. Various sensors for acquiring the engine operating state such as are included. The ECU 40 is electrically connected to an accelerator position sensor 46 that detects the amount of depression of the accelerator pedal (accelerator opening) of the vehicle on which the internal combustion engine 10 is mounted.

  The actuator from which the ECU 40 outputs an operation signal includes various actuators for controlling the engine operation such as the throttle valve 24, the fuel injection valve 26, and the ignition device 28 described above. Further, the ECU 40 has a function of acquiring an output signal of the in-cylinder pressure sensor 30 by performing AD conversion in synchronization with the crank angle. Thereby, the in-cylinder pressure at an arbitrary crank angle timing can be detected within a range allowed by the AD conversion resolution. Further, the ECU 40 stores a map that defines the relationship between the crank angle and the in-cylinder volume in the memory, and can calculate the in-cylinder volume corresponding to the crank angle with reference to such a map.

ただし、上記（１）式において、θ_ｍｉｎは燃焼開始点であり、θ_ｍａｘは燃焼終了点である。 [Control of Embodiment 1]
(Calculation of MFB and CAX based on this)
According to the system of the present embodiment including the in-cylinder pressure sensor 30 and the crank angle sensor 42, it is possible to acquire measured data (in-cylinder pressure waveform) of the in-cylinder pressure in synchronization with the crank angle in each cycle of the internal combustion engine 10. . The in-cylinder heat generation amount Q at an arbitrary crank angle θ can be calculated using the obtained in-cylinder pressure waveform and the first law of thermodynamics. Then, using the actually measured data (heat generation amount waveform) of the heat generation amount Q in the cylinder, the combustion mass ratio (hereinafter referred to as “MFB”) at an arbitrary crank angle θ is expressed by the following equation (1): It can be calculated according to In addition, by executing the MFB calculation process for each predetermined crank angle, it is possible to calculate MFB actual measurement data (MFB waveform) in synchronization with the crank angle. Further, when the MFB actual measurement data is obtained, the crank angle CAX when the MFB becomes the specific ratio X can be calculated.

However, in the above equation (1), θ _min is the combustion start point, and θ _max is the combustion end point.

(Feedback control of fuel injection amount using SA-CA10)
As a premise, in this embodiment, the lean burn operation is performed at a lean air-fuel ratio larger than the stoichiometric air-fuel ratio. Here, the crank angle period from the ignition timing (SA) to the crank angle (10% combustion point) CA10 when the MFB becomes 10% (more specifically, obtained by subtracting the ignition timing (SA) from CA10). Difference) is referred to as “SA-CA10”. SA-CA10 is one of the ignition index values representative of the ignition delay.

  There is a certain correlation between SA-CA10 and the air-fuel ratio. More specifically, in a lean air-fuel ratio region where the air-fuel ratio is larger than the stoichiometric air-fuel ratio, there is a relationship that SA-CA10 increases as the air-fuel ratio becomes leaner. In the present embodiment, the fuel injection amount is controlled so that the actual SA-CA10, which is the calculated value of SA-CA10 based on the output value of the in-cylinder pressure sensor 30, approaches the target SA-CA10 corresponding to the target air-fuel ratio. The This control is referred to as “SA-CA10 feedback control” for convenience. Specifically, according to the SA-CA10 feedback control, in the cylinder in which the actual SA-CA10 smaller than the target SA-CA10 is obtained, in order to make the actual SA-CA10 larger by making the air-fuel ratio lean, Correction for reducing the fuel injection amount used in the combustion cycle is executed. On the other hand, in the cylinder in which the actual SA-CA10 larger than the target SA-CA10 is obtained, the fuel injection amount used in the next combustion cycle is reduced in order to reduce the actual SA-CA10 by enriching the air-fuel ratio. Increasing correction is performed.

(Ignition timing feedback control using CA50)
In the present embodiment, the calculated value of the crank angle (50% combustion point) CA50 (combustion center of gravity) when the MFB based on the output of the in-cylinder pressure sensor 30 becomes 50% along with the SA-CA10 feedback control during the lean burn operation. The feedback control for adjusting the ignition timing so that the actual CA50 approaches the target CA50 (hereinafter simply referred to as “CA50 feedback control”) is executed. More specifically, according to the CA50 feedback control, in the cylinder in which the actual CA50 is obtained as a value retarded from the target CA50, the ignition timing used in the next combustion cycle is used to advance the actual CA50. Correction to advance is executed. On the other hand, in the cylinder in which the actual CA50 is obtained as the value on the advance side of the target CA50, in order to retard the actual CA50, correction for retarding the ignition timing used in the next combustion cycle is executed. The

(Problems during transient operation)
During transient operation in which engine conditions such as engine speed and engine load factor change transiently, the actual air-fuel ratio tends to deviate from the target air-fuel ratio. More specifically, the cause of such an air-fuel ratio shift is mainly a shift in the amount of air taken into the cylinder. This air quantity deviation is mainly due to a delay in air transportation. Further, as the air amount deviation, the residual gas amount (internal EGR gas amount) changes due to the back pressure changing due to a transient change in the opening / closing timing of the intake / exhaust valve, and accordingly, during the intake stroke A deviation in the air amount due to a change in the in-cylinder pressure is also included. Further, the cause of the air-fuel ratio deviation includes a fuel quantity deviation in addition to the air quantity deviation. The fuel amount deviation can be caused by, for example, fluctuations in fuel pressure. Further, in the case of in-cylinder injection, the fuel amount deviation can occur due to a change in the differential pressure between the in-cylinder pressure (gas pressure) and the fuel pressure.

(Setting of response speed of feedback control of embodiment 1)
In this embodiment, when both SA-CA10 feedback control and CA50 feedback control are executed during transient operation, overshoot with respect to the target values (target SA-CA10 and target CA50) of the control amounts (real SA-CA10 and actual CA50) is performed. In order to reduce this, these two feedback controls are configured as follows. That is, in this embodiment, the response speed of the fuel injection amount adjustment by the SA-CA10 feedback control is higher than the response speed of the ignition timing adjustment by the CA50 feedback control.

(Specific processing in Embodiment 1)
FIG. 2 is a flowchart showing a main routine of control executed in the first embodiment of the present invention. This routine is started at the timing when the opening timing of the exhaust valve 22 has elapsed in each cylinder (that is, when the acquisition of the data of the in-cylinder pressure P, which is the basis of calculation of the MFB actual measurement data), and Repeated every combustion cycle.

  In the main routine shown in FIG. 2, the ECU 40 first determines whether or not the lean burn operation is being performed (step 100). In the internal combustion engine 10, a lean burn operation is performed at an air-fuel ratio larger (lean) than the stoichiometric air-fuel ratio in a predetermined operation region. Here, it is determined whether or not the current operation region corresponds to an operation region in which such lean burn operation is performed. The operation region here can be defined based on, for example, the engine load factor and the engine speed.

In step 100 if it is determined that the lean-burn operation, ECU 40 sets the SA-CA10 feedback control and CA50 rotation moderation respectively used for the calculation of the correction amount of the feedback control _{N F} and _{N S} (step 102). More specifically, smoothing number _{N F} for SA-CA10 feedback control is smaller than the averaging count _{N S} for CA50 feedback control.

  Next, the ECU 40 executes processing related to SA-CA10 feedback control (step 104). FIG. 3 is a flowchart showing a subroutine representing processing related to SA-CA10 feedback control.

  In the subroutine shown in FIG. 3, the ECU 40 first acquires the engine load factor and the engine rotation speed (step 200). The engine speed can be calculated using the crank angle sensor 42. The engine load factor can be calculated based on the intake air flow rate detected by the air flow sensor 44, the throttle opening, the valve timing of the intake and exhaust valves 20 and 22, and the engine speed.

  Next, the ECU 40 calculates a target SA-CA10 (step 202). The ECU 40 stores a map (not shown) that defines the target SA-CA10 in relation to the engine load factor and the engine speed. In step 202, the target SA-CA10 corresponding to the engine load factor and the engine speed is calculated with reference to such a map.

  Next, the ECU 40 uses the output value of the in-cylinder pressure sensor 30 to acquire in-cylinder pressure data on a crank angle basis (step 204). Next, the ECU 40 acquires a target ignition timing (step 206). The target ignition timing is a value obtained by adding the latest correction amount of the ignition timing by CA50 feedback control to the basic ignition timing according to the engine load factor and the engine speed.

  Next, the ECU 40 calculates actual SA-CA10 (step 208). The actual SA-CA10 is calculated as a crank angle period from the target ignition timing acquired in step 208 to the actual CA10 obtained as an analysis result of the in-cylinder pressure data acquired in step 204. Next, the ECU 40 calculates a difference ΔSA-CA10 between the target SA-CA10 calculated in steps 202 and 208 and the actual SA-CA10 (step 210).

Next, ECU 40 calculates the present value of the smoothing number _{N F} after moderation process using difference [Delta] SA-CA10 _sm (step 212). The following equation (2) represents a general equation for the annealing process. The current value X _sm (n) after the annealing process uses the previous value X _sm (n−1) after the annealing process, the current value X (n) before the annealing process, and the number N of annealing. (2). Therefore, averaging the previous value of the difference ΔSA-CA10sm after processing, _X sm (n in the difference [Delta] SA-CA10 calculated in step 210, and SA-CA10 for feedback control smoothing the number _{N F,} respectively (2) -1), X (n) and N are substituted, and the current value of the difference ΔSA−CA10 _sm after the annealing process can be calculated.

Next, the ECU 40 uses the calculated difference and a predetermined PI gain (proportional term gain and integral term gain), and the injection amount corresponding to the difference ΔSA−CA10 _sm after the annealing process and the magnitude of the integrated value. A correction amount is calculated (step 214). Then, the ECU 40 corrects the fuel injection amount used in the next cycle by adding the injection amount correction amount calculated in step 214 to the basic fuel injection amount based on the engine load factor and the engine rotation speed ( Step 216).

  In the main routine shown in FIG. 2, the ECU 40 executes a process related to the CA50 feedback control following the process related to the SA-CA10 feedback control in Step 104 (Step 106). FIG. 4 is a flowchart showing a subroutine showing processing related to CA50 feedback control.

  In the subroutine shown in FIG. 4, the ECU 40 first acquires the target ignition efficiency together with the engine load factor and the engine speed (step 300). The ignition efficiency is an index relating to the engine torque generation efficiency by adjusting the ignition timing, and is 1 (peak value) in CA50 when the ignition timing is controlled to the MBT (Minimum advance for the Best Torque) ignition timing. Also, when CA50 is advanced or retarded by adjusting the ignition timing, it decreases.

  Next, the ECU 40 calculates a target CA50 (step 302). Target CA50 is set based on the engine speed, engine load factor, and target ignition efficiency acquired in step 300. Next, the ECU 40 acquires in-cylinder pressure data (step 304), and calculates an actual CA 50 using the analysis result of the acquired in-cylinder pressure data (step 306). Next, the ECU 40 calculates a difference ΔCA50 between the target CA50 calculated in steps 302 and 306 and the actual CA50 (step 308).

Next, ECU 40 calculates the present value of the smoothing number _N difference after moderation treatment with _{S ΔCA50 sm} (step 310). The current value of the difference ΔCA50 _sm after the annealing process can be calculated using the above equation (2), similarly to the difference ΔSA−CA10. Next, the ECU 40 uses the calculated difference and a predetermined PI gain (proportional term gain and integral term gain) to calculate the ignition timing correction amount corresponding to the difference ΔCA50 _sm after the annealing process and the magnitude of the integrated value. Calculate (step 312). Then, the ECU 40 corrects the ignition timing used in the next cycle by adding the calculated ignition timing correction amount to the basic ignition timing (step 314).

According to the routines shown in FIGS. 2 to 4 described above, the injection amount correction amount by the SA-CA10 feedback control and the ignition timing correction amount by the CA50 feedback control are the difference ΔSA−CA10 _sm and ΔCA50 after the annealing process, respectively. Calculated using _sm . Then, according to the process of step 102, smoothing number _{N F} for SA-CA10 feedback control is smaller than the averaging count _{N S} for CA50 feedback control. Such moderation number N _F, according to the setting of the N _S, the response speed of the adjustment of the fuel injection amount by the SA-CA10 feedback control is enhanced than the response speed of the adjustment of the ignition timing by the CA50 feedback control.

  During transient operation, as described above, the actual air-fuel ratio tends to deviate from the target air-fuel ratio. The following effects can be obtained by increasing the response speed for adjusting the fuel injection amount higher than the response speed for adjusting the ignition timing as described above during transient operation. That is, when the air-fuel ratio shift occurs, the fuel injection amount, which is a parameter to be adjusted first to suppress the air-fuel ratio shift, is quickly corrected. Thus, according to the above setting, it is possible to advance the correction of the fuel injection amount more effectively to cope with the air-fuel ratio deviation. As a result, the control amount (actual SA-CA10 and actual CA50) exceeds the target value (target SA-CA10 and target CA50) because the adjustment of the ignition timing proceeds rapidly contrary to such setting. You can reduce shooting. As a result, it is possible to suppress the deterioration of exhaust emission and drivability due to the above-described air-fuel ratio shift. In addition, in the actual use environment of the vehicle on which the internal combustion engine is mounted, transient operation is used more than steady operation. For this reason, according to the present embodiment, the response speed of each feedback control can be set so as to be appropriate at the time of transient operation frequently used during actual use of the vehicle.

Embodiment 2. FIG.
Next, Embodiment 2 of the present invention will be described with reference mainly to FIG. In the following description, the configuration shown in FIG. 1 is used as an example of the system configuration of the second embodiment.

[Control of Embodiment 2]
In the first embodiment described above, the response speed of the fuel injection amount adjustment by the SA-CA10 feedback control is the same as the ignition timing adjustment by the CA50 feedback control regardless of whether the operation is transient or steady operation. It is higher than the response speed. Here, when the above setting of the response speed is used during steady operation, the injection amount correction amount is likely to fluctuate finely under the influence of variations in the actual air-fuel ratio between combustion cycles. Therefore, during steady operation, it may be better to use a setting opposite to the above setting (that is, a setting in which the response speed of ignition timing adjustment is relatively high) for the following reason. That is, during steady-state operation, it is more effective to adjust the fuel injection amount relatively slowly while increasing the response speed of adjustment of the ignition timing to bring the actual CA50 closer to an appropriate value (target CA50) during lean burn combustion. It can be said that it is preferable in approaching the lean combustion limit.

  Therefore, in this embodiment, when both the SA-CA10 feedback control and the CA50 feedback control are executed, it is determined whether the operation is transient or steady. In addition, when it is determined that the engine is in the transient operation, the setting in which the response speed of the adjustment of the fuel injection amount is relatively high is used as in the first embodiment, and on the other hand, the engine is determined to be in the steady operation. For this, a setting is used in which the response speed of the ignition timing adjustment is relatively high.

(Specific processing in Embodiment 2)
FIG. 5 is a flowchart showing a main routine of control executed in the second embodiment of the present invention. In FIG. 5, the same steps as those shown in FIG. 2 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

In the main routine shown in FIG. 5, if the ECU 40 determines in step 100 that the lean burn operation is being performed, then it determines whether or not the ECU 40 is in steady operation (transient operation) (step 400). ). More specifically, whether the engine is in steady operation or transient operation is based on, for example, whether the engine load factor change rate with time (d load factor / dt) is less than a predetermined value _Kth. Can be determined. In addition, the determination as to whether or not the vehicle is in steady operation may be performed using one or more of the following methods, for example, instead of or together with the above method.

  That is, the above determination may be made based on whether or not the temporal change rate of the engine rotation speed is less than a predetermined value. Further, when the difference ΔSA-CA10 between the target SA-CA10 and the actual SA-CA10, which is a value corresponding to the engine operating condition, is less than a predetermined value, it is determined that steady operation is being performed, and the difference ΔSA-CA10 is You may determine that it is in transient operation when it is more than the above-mentioned predetermined value. Furthermore, the following determination may be performed in a hybrid vehicle including an internal combustion engine 10 and an electric motor as a power source, or a vehicle in which the internal combustion engine 10 is combined with a continuously variable transmission (CVT). That is, in these vehicles, a steady mode in which the internal combustion engine 10 is operated as steady as possible by controlling the electric motor or the CVT when the vehicle required torque changes may be used. When a high torque that cannot be satisfied in such a steady mode is required, a transient mode that satisfies the torque request using the internal combustion engine 10 may be used. In a vehicle in which such control is performed, for example, when the rate of change of the accelerator opening is less than a predetermined value, it is determined that the steady mode is being used, and therefore, it is in steady operation, When the rate of change of the accelerator opening is equal to or greater than the predetermined value, it is determined that the transient mode is being used, and therefore the transient operation is being performed. Further, in a vehicle equipped with a CVT, when a manual mode in which the driver selects the CVT gear ratio is selected, it is determined that the vehicle is in transient operation, and the vehicle automatically controls the CVT gear ratio. When the mode is selected, it may be determined that steady operation is being performed.

If the ECU 40 determines that the transient operation is being performed in step 400, the ECU 40 selects the setting of the number of annealings (N _F <N _S ) similar to that of the first embodiment in step 102, while the steady operation is being performed. When it is determined that there is, the setting of the number of times of annealing (N _F > N _S ) opposite to the above is selected (step 402). Subsequent CA50 feedback control of the SA-CA10 feedback control and step 106 of step 104, the number _{N F} and _{N S} moderation is set in step 102 or 402 depending on the determination result of step 400 is used, respectively.

According to the routine shown in FIG 5 described above, depending on whether is in transient operation or is in steady operation, setting the smoothing number N _F and N _S are different. Specifically, during transient operation, the same smoothing constant setting as in the first embodiment is used, so that the control amount (actual SA-CA10 and actual CA50) is the target value (target SA-CA10 and target CA50). Overshoot can be reduced. Further, during steady operation, the response speed for adjusting the ignition timing can be made higher than the response speed for adjusting the fuel injection amount by setting an annealing constant opposite to that in the first embodiment. Therefore, it is possible to satisfactorily perform control to bring the air-fuel ratio closer to the lean combustion limit during steady operation in which lean burn combustion is performed. As described above, according to the control of the present embodiment, the fuel injection amount and the ignition timing can be adjusted at an appropriate response speed in each of the transient operation and the steady operation.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference mainly to FIG. 6 and FIG. In the following description, it is assumed that the configuration shown in FIG. 1 is used as an example of the system configuration of the third embodiment.

[Control of Embodiment 3]
Any feedback control potentially involves a response delay. Therefore, in the present embodiment, unlike the first and second embodiments, as a measure for suppressing the deterioration of exhaust emission and drivability due to the above-described air-fuel ratio shift, the control of the fuel injection amount during the transient operation is performed. As a feedforward control is used.

  Specifically, in the present embodiment, during transient operation, the SA-CA10 feedback control is stopped, and the following injection amount with respect to the basic fuel injection amount according to the engine rotation speed and the engine load factor: The fuel injection amount is controlled by a value obtained by adding the increase value. That is, the fuel injection amount is adjusted using a preset injection amount increase value based on the engine load factor and the engine load factor. The CA50 feedback control is also executed in this embodiment regardless of whether it is during transient operation.

(Specific processing in Embodiment 3)
FIG. 6 is a flowchart showing a main routine of control executed in the third embodiment of the present invention. In FIG. 6, the same steps as those shown in FIG. 2 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

In the main routine shown in FIG. 6, when the ECU 40 determines that the lean burn operation is performed in step 100, the ECU 40 sets the number of times of annealing in step 402 (N _F > N _S ). Next, the ECU 40 determines whether or not it is in steady operation (transient operation) (step 400). The processing in the case where it is determined in step 400 that the vehicle is in steady operation is the same as that in the second embodiment.

  On the other hand, when it is determined in step 400 that the engine is in a transient operation, the ECU 40 calculates an injection amount increase value (step 500). FIG. 7 is an image diagram for explaining the setting of a map referred to for determining the injection amount increase value in the third embodiment of the present invention. In this map, the injection amount increase value is set based on the engine load factor and the engine load factor for each predetermined engine speed. The injection amount increase value is set in advance as a value that does not deteriorate combustion or cause misfire even if uncertain elements that cannot be assumed are included. More specifically, the injection amount increase value is set so as to increase as the engine load factor increases with time and as the engine load factor decreases. Therefore, according to the setting of the map, the injection amount increase value becomes the largest when the time change rate of the engine load factor is large and the engine load factor is small.

Next, the ECU 40 adds the injection amount increase value calculated in step 500 to the basic fuel injection amount (step 502). During transient operation, feed-forward control of the fuel injection amount is executed by the processing of step 502. Note that, as described above, the basic fuel injection amount is calculated as a value corresponding to the engine speed and the engine load factor. Next, the ECU 40 executes CA50 feedback control even during transient operation (step 106). Also in CA50 feedback control performed in this case, the number N _S moderation calculated in step 402 is used.

  According to the routine shown in FIG. 6 described above, during the transient operation, the SA-CA10 feedback control is stopped, and the basic fuel injection amount is equal to the fuel injection amount calculated according to the relationship shown in FIG. Is increased from The engine load factor is a filling rate of the amount of air taken into the cylinder. When the engine load factor changes by a certain change amount, the smaller the engine load factor, the larger the ratio of the change amount to the engine load factor value. For this reason, the influence of the air-fuel ratio deviation (mainly, the air quantity deviation) during transient operation increases as the engine load factor decreases. Further, when the time change rate of the engine load factor increases, the air-fuel ratio shift increases. According to the setting of the map shown in FIG. 7, the injection amount increase value can be determined so as to increase as the influence of the air-fuel ratio shift increases. As a result, the fuel injection amount can be appropriately increased by an amount for suppressing an air-fuel ratio shift assumed when fuel injection is performed with the basic fuel injection amount during transient operation. According to such a technique, in a situation where an increase in the fuel injection amount is required, if feedback control is used for adjusting the fuel injection amount, the air-fuel ratio cannot be corrected due to a response delay. It becomes possible to suppress deterioration of drivability and exhaust emission that may occur.

  Note that, according to the routine shown in FIG. 6, the main control after the SA-CA10 feedback control is stopped during the transient operation is resumed when the determination in step 400 is established (when the operation returns to the steady operation). become. However, the method of resuming the present control is not limited to the above, and may be immediately after the fuel injection amount is increased by the injection amount increase value after it is determined in step 400 that the transient operation is being performed, for example.

  In addition, as described above, the injection amount increase value is set as a value such that combustion does not deteriorate or misfire does not occur even if an uncertain element that cannot be assumed is included. Here, the injection amount increase value can be decreased by retarding the target CA50 with respect to the value of CA50 when the MBT ignition timing is obtained. More specifically, the in-cylinder temperature and the in-cylinder pressure are the highest by retarding the target CA50 so that the ignition timing (≈combustion start point CA0) is near the compression top dead center during execution of the CA50 feedback control. Since the ignition can be performed in the state, the ignitability is improved. For this reason, by retarding the target CA50, it is possible to reduce the amount of fuel injection necessary to ensure equivalent ignitability. Therefore, the retarded angle can reduce the injection amount increase value. Therefore, in order to obtain such an effect of reducing the injection amount increase value, a map of setting obtained by replacing the injection amount increase value in the setting of the map shown in FIG. The retardation amount of the target CA 50 during transient operation may be determined based on the time change rate of the load factor and the engine load factor. According to such a map, the target CA50 can be set so that the retardation amount increases when the injection amount increase value is increased as the air-fuel ratio deviation increases.

Incidentally, in the first to third embodiments described above, by executing the than smoothing number N _S for CA50 feedback control moderation utilizing smoothing number N _F for small SA-CA10 feedback control process In the transient operation, the response speed of the fuel injection amount adjustment by the SA-CA10 feedback control is higher than the response speed of the ignition timing adjustment by the CA50 feedback control. However, the realization method of this configuration may use, for example, the setting of the feedback gain instead of or using the setting of the number of times of annealing. Specifically, for example, the above configuration may be realized by making the PI gain used for SA-CA10 feedback control larger than the PI gain used for CA50 feedback control. The same applies to the reverse setting to that described above during steady operation.

Moreover, in Embodiment 1-3 mentioned above, SA-CA10 was illustrated as an ignition delay index value representing an ignition delay. However, the “ignition delay index value” in the present invention only needs to include an ignition delay period (a crank angle period from the ignition timing to the time when heat generation starts (combustion start point CA0)), and instead of SA-CA10, For example, a crank angle period from the ignition timing (SA) to an arbitrary specific combustion point CAX1 other than CA10 can be used. Further, the “combustion time index value” may be an index value representative of the combustion time, and may be, for example, any specific ratio combustion point CAX2 other than CA50 instead of the exemplified CA50, or MBT. It may be an ignition timing change amount from the ignition timing. Furthermore, the cylinder pressure maximum crank angle θ _Pmax may be used.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 14 Combustion chamber 24 Throttle valve 26 Fuel injection valve 28 Ignition device 30 In-cylinder pressure sensor 40 Electronic control unit (ECU)
42 Crank angle sensor 44 Air flow sensor 46 Accelerator position sensor

Claims (3)

A control device for controlling an internal combustion engine comprising: an ignition device that ignites an air-fuel mixture in a cylinder; a fuel injection valve that supplies fuel into the cylinder; and an in-cylinder pressure sensor that detects an in-cylinder pressure;
Index value calculation means for calculating an actual ignition delay index value and an actual combustion timing index value based on the output value of the in-cylinder pressure sensor;
First feedback control means for performing feedback control of the fuel injection amount so that the actual ignition delay index value approaches the target ignition delay index value;
Second feedback control means for executing feedback control of ignition timing so that the actual combustion timing index value approaches the target combustion timing index value;
With
In the transient operation of the internal combustion engine, the first feedback control means and the second feedback control means are configured such that a response speed of adjustment of the fuel injection amount by the first feedback control means is the second feedback control means. A control device for an internal combustion engine, characterized in that it is configured to be higher than a response speed of adjustment of ignition timing by the engine. A control device for controlling an internal combustion engine comprising: an ignition device that ignites an air-fuel mixture in a cylinder; a fuel injection valve that supplies fuel into the cylinder; and an in-cylinder pressure sensor that detects an in-cylinder pressure;
Index value calculation means for calculating an actual ignition delay index value and an actual combustion timing index value based on the output value of the in-cylinder pressure sensor;
First feedback control means for performing feedback control of the fuel injection amount so that the actual ignition delay index value approaches the target ignition delay index value;
Second feedback control means for executing feedback control of ignition timing so that the actual combustion timing index value approaches the target combustion timing index value;
During transient operation of the internal combustion engine, instead of adjusting the fuel injection amount by the first feedback control means, the fuel injection amount using the time change rate of the engine load factor and the injection amount increase value based on the engine load factor is changed. A transient adjustment means for performing the adjustment;
Equipped with a,
The injection amount increase value is an increase value with respect to the basic fuel injection amount,
During steady operation of the internal combustion engine, the feedback control of the fuel injection amount by the first feedback control means and the feedback control of the ignition timing by the second feedback control means are executed,
During the transient operation, of the feedback control of the fuel injection amount by the first feedback control means and the feedback control of the ignition timing by the second feedback control means, the ignition timing by the second feedback control means A control apparatus for an internal combustion engine, wherein only feedback control is executed . The second feedback control means retards the target combustion timing index value during the transient operation from a value when the MBT ignition timing is obtained.
The control apparatus for an internal combustion engine according to claim 2.

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