JP2015166559A - Internal combustion engine controller - Google Patents

Abstract

A control device for an internal combustion engine capable of suppressing an excessive temperature rise of a catalyst due to an ignition timing retardation.
When there is a request for retarding an ignition timing, a control device 80 corrects the ignition timing with a retard correction amount according to the retard request, and injects fuel according to the retard correction amount. Correct the amount by increasing. This control device 80, for a cylinder that is predicted not to be in time for an increase in the fuel injection amount due to the increase correction with respect to the ignition timing retardation correction, the ignition timing retardation correction amount of the cylinder meets the retardation request. Limit the amount to be smaller than the retardation correction amount.
[Selection] Figure 1

Description

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

  In an internal combustion engine, in order to suppress the occurrence of torque shock or the like, the ignition timing is sometimes retarded. Such ignition timing retardation correction causes an increase in the exhaust gas temperature, and thus the catalyst provided in the exhaust passage may be damaged by heat.

  Therefore, when there is a concern about an excessive increase in the temperature of the catalyst, for example, as described in Patent Document 1, by increasing the fuel injection amount to increase the heat of vaporization of the fuel, the exhaust temperature and the catalyst temperature are increased. Processing to suppress the rise is performed.

JP 2009-19521 A

By the way, in order to suppress an increase in the temperature of the catalyst, it is necessary that the fuel whose amount has been corrected for increase has reached the combustion chamber by the timing of ignition whose angle has been corrected.
Here, for example, the actual ignition timing delay based on the retard angle request can be executed promptly, but a certain period of time is required to inject the fuel with the increased correction. Further, when the ignition timing is retarded, it is necessary to increase the amount of fuel prior to the ignition timing retardation.

For this reason, in some cases, there is a state in which the increase in the fuel injection amount is not in time for the ignition timing retardation correction, and the temperature of the catalyst may be excessively high although it is temporary.
It should be noted that during a high load operation where the fuel injection amount is large or during a high rotation operation where the crank angular speed is high, the period required to inject the required fuel, that is, the fuel injection period (generally, the fuel injection period) Is controlled by the crank angle), the above-described state is particularly likely to occur.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for an internal combustion engine that can suppress an excessive temperature rise of the catalyst due to ignition timing retardation.

  The control apparatus for an internal combustion engine that solves the above-described problem, when there is a request for retarding the ignition timing, retards the ignition timing by a retard correction amount according to the retard request, and also corrects the retard of the ignition timing. The fuel injection amount is corrected to increase according to the amount. For a cylinder that is predicted not to be able to make an increase in the fuel injection amount due to the increase correction with respect to the ignition timing delay correction, the control timing of the ignition timing of the cylinder is determined according to the above-described retardation request. It is limited so as to be less than the retard correction amount.

  According to this configuration, for a cylinder that is predicted not to be in time for the fuel injection amount increase due to the increase correction with respect to the ignition timing retardation correction, the ignition timing retardation correction amount of the cylinder is the retardation request. It is limited to be smaller than the retardation correction amount according to. Therefore, an increase in the exhaust gas temperature due to the ignition timing retardation correction can be suppressed in a cylinder in which the fuel increase is not in time, thereby suppressing an excessive temperature rise of the catalyst due to the ignition timing retardation.

  As the fuel injection period becomes longer, the number of cylinders that are predicted not to be able to increase the fuel injection amount due to the increase correction with respect to the ignition timing retardation correction increases. Therefore, the ignition timing retardation correction amount is limited. The cylinder to be determined can be obtained based on, for example, the fuel injection period.

The schematic block diagram of the internal combustion engine to which this is applied about one Embodiment of the control apparatus of an internal combustion engine. The flowchart which shows the process sequence when restrict | limiting an ignition timing retardation. The timing chart which shows the fuel injection and ignition mode in each cylinder.

Hereinafter, an embodiment embodying a control device for an internal combustion engine will be described with reference to FIGS.
As shown in FIG. 1, a multi-cylinder engine 1 to which this control device is applied includes a plurality of cylinders 3 in a cylinder block 2 (only one is shown in FIG. 1).

  A piston 4 provided in each cylinder 3 is connected to a crankshaft 5 via a connecting rod 6. By this connecting rod 6, the reciprocating motion of the piston 4 is converted into the rotational motion of the crankshaft 5. The crankshaft 5 is connected to the input shaft of the automatic transmission 100 that automatically switches the gear position.

  A cylinder head 7 is attached to the upper part of the cylinder block 2. In the cylinder 3, a combustion chamber 8 is formed between the upper end of the piston 4 and the cylinder head 7.

  A spark plug 11 is provided in the combustion chamber 8. An intake passage 14 and an exhaust passage 15 are connected to the intake port 12 and the exhaust port 13 communicating with the combustion chamber 8, respectively. The intake port 12 is provided with an injector 16 for injecting fuel.

An intake valve 17 and an exhaust valve 18 provided in the cylinder head 7 open and close the intake port 12 and the exhaust port 13, respectively.
The intake valve 17 opens and closes when a cam provided on the intake camshaft 31 rotates as the intake camshaft 31 rotates. The exhaust valve 18 opens and closes when a cam provided on the camshaft 32 rotates as the exhaust camshaft 32 rotates.

  A timing pulley 33 provided at the tip of the intake camshaft 31 and a timing pulley 34 provided at the tip of the exhaust camshaft 32 are drivingly connected to the crankshaft 5 via a timing belt 35. When the crankshaft 5 rotates twice, each timing pulley 33, 34 rotates once.

  During operation of the engine 1, the rotational force of the crankshaft 5 is transmitted to the intake side camshaft 31 and the exhaust side camshaft 32 via the timing belt 35 and the timing pulleys 33 and 34.

Thus, the intake valve 17 and the exhaust valve 18 open and close at a predetermined timing in synchronization with the rotation of the crankshaft 5, that is, corresponding to the reciprocating movement of each piston 4.
The timing pulley 33 provided on the intake side camshaft 31 is provided with an intake side variable valve mechanism (hereinafter referred to as IN-VVT mechanism) 60a. By driving the IN-VVT mechanism 60a, the relative rotational phase of the intake camshaft 31 with respect to the crankshaft 5 is changed, and the valve timing of the intake valve 17 is changed.

  The timing pulley 34 provided on the exhaust side camshaft 32 is provided with an exhaust side variable valve mechanism (hereinafter referred to as EX-VVT mechanism) 60b. By driving the EX-VVT mechanism 60b, the relative rotational phase of the exhaust camshaft 32 with respect to the crankshaft 5 is changed, and the valve timing of the exhaust valve 18 is changed.

  A surge tank 51 for suppressing intake pulsation is provided in the middle of the intake passage 14. On the upstream side of the surge tank 51, a throttle valve 53 whose opening degree is changed based on the operation of the accelerator pedal 52 is provided. By changing the opening of the throttle valve 53, the amount of air taken into the combustion chamber 8 is adjusted.

  A high voltage output from the igniter 46 is supplied to the spark plug 11. The ignition timing of the spark plug 11 is determined by the output timing of the high voltage from the igniter 46.

  Then, an air-fuel mixture composed of intake air supplied from the intake passage 14 and fuel injected from the injector 16 is ignited by the spark plug 11, and the air-fuel mixture is combusted in the combustion chamber 8 to produce engine output. Occur. Combustion gas generated by the combustion of the air-fuel mixture is discharged to the exhaust passage 15.

In the middle of the exhaust passage 15, a catalyst 70 for purifying exhaust (combustion gas) from the combustion chamber 8 is provided.
The engine 1 is provided with various sensors.

  For example, a crank angle sensor 41 is provided in the vicinity of the crankshaft 5. The crank angle sensor 41 detects the rotation (crank angle) of the crankshaft 5 and detects the engine speed NE based on the detection result. Further, a cam angle sensor 42a is provided in the vicinity of the intake side camshaft 31, and the rotation phase of the intake side camshaft 31 is detected based on the output signals of the cam angle sensor 42a and the crank angle sensor 41. The valve timing of the intake valve 17 is detected. Similarly, a cam angle sensor 42b is provided in the vicinity of the exhaust side camshaft 32, and the rotational phase of the exhaust side camshaft 32 is detected based on the output signals of the cam angle sensor 42b and the crank angle sensor 41. As a result, the valve timing of the exhaust valve 18 is detected. A throttle opening sensor 54 for detecting the opening is attached to the throttle valve 53. Further, on the upstream side of the throttle valve 53, an air flow meter 56 that provides an output corresponding to the intake air amount GA taken into the engine 1 is provided.

  Various controls such as the ignition timing control of the engine 1, the fuel injection amount control, or the valve timing control of the intake valve 17 and the exhaust valve 18 based on the phase control of the IN-VVT mechanism and the EX-VVT mechanism are performed by the control device 80. .

  The control device 80 is configured around a microcomputer including a central processing control device (CPU). For example, the control device 80 is provided with a read-only memory (ROM) in which various programs, maps, and the like are stored in advance, and a random access memory (RAM) in which CPU calculation results and the like are temporarily stored.

  The control device 80 is also provided with a backup RAM, an input interface, an output interface, and the like for storing calculation results and prestored data after the engine is stopped. And the operation state of the engine 1 is detected by the output signal from the said various sensors being input through an input interface.

  On the other hand, the output interface is connected to the drive actuators and the like of the injector 16, the igniter 46, the IN-VVT mechanism 60a, and the EX-VVT mechanism 60b through corresponding drive circuits. The control device 80, based on the signals from the various sensors and the like, in accordance with the control program and initial data stored in the ROM, the injector 16, igniter 46, IN-VVT mechanism 60a, EX-VVT mechanism 60b, etc. To control.

  The control device 80 sets the ignition timing and the fuel injection amount based on the engine operating condition such as the engine load factor KL (the ratio of the current intake air amount GA to the intake air amount GA at full load), the engine rotational speed NE, and the like. .

  Here, when the output torque of the engine 1 is temporarily reduced during the shift of the automatic transmission 100, a torque shock during the shift can be suppressed. Therefore, at the time of shifting the automatic transmission 100, the control device 80 corrects the ignition timing set based on the engine operating state to retard the output torque of the engine 1 temporarily.

  On the other hand, such ignition timing retardation correction tends to cause an increase in exhaust gas temperature, and the catalyst 70 may be thermally damaged. Therefore, when there is a concern about an excessive temperature rise of the catalyst 70 due to the ignition timing retardation correction, the control device 80 increases the fuel vaporization heat to increase the fuel vaporization heat, thereby increasing the exhaust temperature and the catalyst. A process for suppressing a rise in temperature, that is, a so-called OT increase process is executed.

  Here, although the actual ignition timing retardation based on the ignition timing retardation request can be executed promptly, a certain period of time is required to completely inject the corrected fuel. Further, when the ignition timing is retarded, it is necessary to increase the amount of fuel prior to the ignition timing retardation. Therefore, in some cases, there is a state in which the increase in the fuel injection amount is not in time for the correction of the retard of the ignition timing, and the temperature of the catalyst 70 may be excessively high although it is temporary. Note that if the temperature of the catalyst 70 is excessively increased even if it is temporary, the thermal degradation of the catalyst 70 may gradually proceed. Further, since the temporary temperature rise of the catalyst 70 causes a sudden change in temperature distribution in the catalyst 70, there is a possibility that a strong thermal stress acts on the catalyst 70.

  By the way, during high-load operation where the fuel injection amount increases or during high-speed operation where the crank angular speed increases, the period required to blow out the required fuel, that is, the fuel injection period (generally, the fuel injection period Is controlled by the crank angle). Therefore, in such an engine operating state, the above-described state, that is, a state in which the increase in the fuel injection amount is not in time for the ignition timing retardation correction is particularly likely to occur.

  Therefore, in this embodiment, in order to suppress the excessive temperature rise of the catalyst 70 due to such ignition timing retardation, a process for limiting the ignition timing retardation is performed as shown in FIG. This restriction process is executed by the control device 80 every 90 ° CA before compression top dead center of each cylinder.

Incidentally, in the present embodiment, the timing of 90 ° CA before compression top dead center is also the timing at which the final ignition timing is calculated in each cylinder.
When this process is started, it is first determined whether or not there is a retardation request at the time of shifting of the automatic transmission 100 (S100). Here, for example, it is determined whether or not the required retard amount RR of the ignition timing is equal to the required retard amount RRS at the time of shift, that is, whether the required retard amount RRS at the time of shift is set as the required retard amount RR of the ignition timing. Is done.

The shift required retard amount RRS is an ignition timing retard amount corresponding to a retard request for suppressing torque shock at the time of shifting of the automatic transmission 100 described above among various retard requests.
In addition, the various retardation requests include a retardation request for suppressing a torque shock when returning from the fuel cut, and a retardation request for early warming up of the catalyst 70. Further, the retardation required amount RR is a value corresponding to a retardation correction amount for correcting the ignition timing, and is the value with the largest retardation degree among the ignition timing retardation amounts corresponding to various retardation requests. Is selected as the retardation request amount RR.

  When it is determined in step S100 that there is no request for retarding at the time of shifting (S100: NO), in step S200, the retard holding execution count DLY is set to “0”, and this process is temporarily terminated. Is done. The retard hold execution count DLY is the number of times that the ignition timing is held without performing the retard of the ignition timing within a period in which there is a request for retarding the ignition timing.

  On the other hand, when it is determined in step S100 that there is a request for retardation at the time of shifting (S100: YES), it is determined whether or not the number of delay suspension execution times DLY is “0” (S110).

  When the delay angle hold execution count DLY is “0” (S110: YES), that is, when there is a delay request at the time of shifting and there is no history of holding the retard of the ignition timing, step S120. The subsequent processing is executed.

  In step S120, the required increase value EK is calculated based on the retardation request amount RR. Here, the estimated temperature of the catalyst 70 is calculated based on the engine rotational speed NE, the engine load factor KL, the retardation request amount RR, and the like. When the estimated temperature exceeds a predetermined determination temperature, the required increase value EK, which is an increase coefficient of the fuel injection amount required to reduce the temperature of the catalyst 70 to the allowable temperature, is the estimated temperature of the catalyst 70. It is calculated based on the above.

  Next, the basic value of the fuel injection amount is corrected based on the required increase value EK, other increase request values, etc., so that the fuel injection amount for one cylinder that is the calculation target in this process QE is calculated (S130). Since this fuel injection amount QE reflects the required increase value EK, the fuel injection amount QE is the increased fuel injection amount when the above-described OT increase processing is executed.

Next, a fuel injection period ETAU is calculated based on the fuel injection amount QE (S140).
In this step S140, based on various parameters, a time required for injecting an amount of fuel corresponding to the fuel injection amount QE from the injector 16 is calculated, and the calculated injection time is set to the rotation angle of the crankshaft 5. By performing the conversion, the injection period ETAU is calculated. The calculation of the injection period corresponding to the fuel injection amount is well known and can be carried out in an appropriate manner. Hereinafter, an example of calculation of such an injection period will be described.

First, the injection time [μs (microseconds)] corresponding to the fuel injection amount can be obtained from the following equation (1).

Injection time ← {Increase coefficient x (Fuel density x Injector flow rate x Fuel pressure correction coefficient x Air density x Combustion chamber volume x Filling efficiency) / Target air-fuel ratio} + Invalid injection time (1)

The above increase coefficient is a coefficient obtained by integrating the above-described required increase value EK and other increase request values, and is a coefficient for increasing the basic value of the fuel injection amount.

The fuel injection time thus obtained can be converted into the injection period [CA (crank angle)] by the following equation (2) and the following equation (3) based on the engine rotational speed NE.

Angular speed of crankshaft [CA / μs] ← (360 [CA] × engine rotational speed [rpm]) / (60 [sec / min] × 1000000 [μs / sec]) (2)

Injection period [CA] ← Crankshaft angular velocity [CA / μs] × injection time [μs] (3)

Next, the retard hold setting number MSK is calculated according to the calculated injection period ETAU (S150). The retard hold setting number MSK is the number of times that the ignition timing is held without performing the retard of the ignition timing within a period in which there is a request for retarding the ignition timing, and is a value based on the principle described below. .

  That is, when a request for retarding the ignition timing is generated, the fuel injection amount commensurate with the correction of the retarded ignition timing is applied to the cylinder in which fuel injection has already been completed or the cylinder in which fuel injection is being performed. This increase is reflected from the next fuel injection.

  Therefore, it is predicted that the cylinders in which the fuel injection has been completed or the cylinders in which the fuel injection is being performed are cylinders in which the increase in the fuel injection amount due to the increase correction is not in time for the retard correction of the ignition timing. can do.

  Therefore, in the present embodiment, the retard correction amount of the ignition timing is limited to be smaller than the retard correction amount according to the retard request in the cylinder that is predicted to be unable to meet such an increase in the fuel injection amount. Thus, an excessive temperature rise of the catalyst 70 described above is suppressed.

  More specifically, in a cylinder that is predicted not to be in time for the fuel injection amount increase due to the increase correction with respect to the ignition timing delay angle correction, until the fuel injection amount increase is in time, the delay request is met. The set value of the required retard amount RR is limited to “0”, and is substantially held without performing the retard correction of the ignition timing.

  Then, the number of cylinders that are predicted to be inadequate to increase the fuel injection amount due to the increase correction with respect to the ignition timing retardation correction, in other words, the fuel injection amount due to the increase correction with respect to the ignition timing retardation correction. The number of ignitions of the engine 1 within a period in which the increase is predicted not to be in time is set to the above-described retardation hold setting number MSK.

  For example, in the case of an in-line four-cylinder engine, the ignition interval between the cylinders is 180 ° CA. The fuel injection end timing is assumed to be “240 ° CA before compression top dead center”. Incidentally, physically, it is possible to inject fuel into the combustion chamber up to the intake bottom dead center (180 ° CA before compression top dead center).

  In this case, when the injection period ETAU is 180 ° CA or less, the delay hold setting number MSK is set to “2” to increase the fuel injection amount by the increase correction with respect to the ignition timing delay correction. The ignition timing retardation correction in the cylinder that is predicted not to be in time is appropriately suspended.

  Further, when the injection period ETAU exceeds 180 ° CA and is 360 ° CA or less, the delay hold setting number MSK is set to “3” to increase the ignition timing with respect to the retard correction. The retard correction of the ignition timing in the cylinder that is predicted not to be in time for the increase in the fuel injection amount due to is appropriately suspended.

  Further, when the injection period ETAU exceeds 360 ° CA and is equal to or less than 540 ° CA, the delay hold setting number MSK is set to “4” to increase the ignition timing relative to the retard correction. The retard correction of the ignition timing in the cylinder that is predicted not to be in time for the increase in the fuel injection amount due to is appropriately suspended.

  When the injection period ETAU exceeds 540 ° CA and is equal to or shorter than the maximum injection possible period, the retard hold setting number MSK is set to “5” to increase the ignition timing retard correction. The ignition timing retardation correction in the cylinder that is predicted not to be in time for the fuel injection amount increase due to the correction is appropriately suspended. The maximum injectable period is the maximum period in which fuel can be physically injected. For example, the opening operation of the intake valve 17 performed prior to fuel injection is completed for one cylinder. This corresponds to the period from when the intake valve 17 is closed to when fuel injection ends. As an example, inhalation of fresh air used for one ignition is completed at “840 ° CA before compression top dead center”, and fuel injection for the fresh air ends at “240 ° CA before compression top dead center” The maximum injectable period is “840−240 = 600 ° CA”.

  Incidentally, when the injection period ETAU exceeds the maximum possible injection period, the fuel injection is physically impossible, and therefore, for example, the retardation request amount RR is limited to be smaller than the original value. In addition, the injection period ETAU may be shortened to the maximum injection possible period or less.

  In addition to setting the retard hold setting number MSK in advance for each predetermined injection period range in this way, the retard hold setting number MSK may be set, for example, as follows. Is possible.

  That is, since the injection period ETAU changes according to the engine rotational speed NE and the engine load factor KL, a setting map using such an engine rotational speed NE and the engine load factor KL as parameters is constructed, and the delay is determined from the setting map. The corner hold setting number MSK may be obtained.

  After the calculation of the retard hold setting number MSK according to the injection period ETAU in this way, or when it is determined in step S110 that the delay hold execution number DLY is not “0” (S110: NO). Then, it is determined whether or not the delay hold execution count DLY is equal to or greater than the delay hold set count MSK (S160).

  If the retard hold execution count DLY is less than the retard hold set count MSK (S160: NO), it is predicted that the fuel injection amount increase due to the increase correction will not be in time for the retard correction of the ignition timing. In this case, as described above, the required retard amount RR is set to “0” (S170), and the retard of the ignition timing is suspended.

Then, by adding “1” to the delay hold execution count DLY, the delay hold execution count DLY is updated (S180), and this process is temporarily terminated.
On the other hand, when it is determined in step S160 that the retard hold execution count DLY is equal to or greater than the retard hold set count MSK (S160: YES), the fuel injection amount by the increase correction with respect to the retard correction of the ignition timing. It is determined that the increase in the amount is in time for all cylinders. In this case, as the value of the retardation request amount RR that has been limited to “0” until then, the value of the shift retardation request amount RRS is set (S190), and in response to the retardation request. The ignition timing is retarded.

Then, the delay hold execution count DLY is reset to “0” (S200), and this process is temporarily terminated.
Next, with reference to FIG. 3, the effect | action by the said limitation process is demonstrated. Note that the example shown in FIG. 3 is merely an example.

  First, the engine 1 is an in-line four-cylinder internal combustion engine, the ignition interval between the cylinders is “180 ° CA”, the fuel injection end timing is “240 ° CA before compression top dead center”, and the amount of increase is corrected. The fuel injection period ETAU is assumed to be “480 ° CA”. The ignition order of each cylinder is “1st cylinder # 1 → 3rd cylinder # 3 → 4th cylinder # 4 → 2nd cylinder # 2”. Further, it is assumed that the opening timing of the intake valve 17 is “360 ° CA before compression top dead center” and the closing timing of the intake valve 17 is “120 ° CA before compression top dead center”.

  Further, in order to show the correspondence between the fuel injected for each combustion cycle in each cylinder and the ignition timing of the injected fuel, the fuel injected in the “injection period (n)” It is assumed that ignition is performed by the ignition (n) indicated by “ For example, in the first cylinder # 1, the fuel that has been injected from the time t1 and injected and supplied within the “injection period (5)” is ignited by the “ignition (5)” at the time t5.

  As shown in FIG. 3, when a delay angle request at the time of shifting occurs at time t0, each cylinder thereafter calculates a final ignition timing corresponding to the delay angle request every 90 ° CA before compression top dead center. The restriction process is executed. In addition, fuel injection amount increase calculation is performed within the period from time t0 to time t1, and after time t1, OT increase is executed, so that in each cylinder, the fuel injection amount corresponding to the retardation required amount RR. The amount of increase is performed.

  Here, for example, when the ignition (1), which is the first ignition after the request for retarding, is performed in the first cylinder # 1 at the time t1, the fuel ignited here is a timing before the time t1. In other words, the fuel has already been injected and has not been subjected to OT increase. Therefore, if the ignition timing at the ignition (1) is corrected to be retarded, an increase in the fuel injection amount is insufficient with respect to the ignition timing that has been corrected for the retard.

  Further, for example, when ignition (2), which is the second ignition after the request for retarding, is performed in the third cylinder # 3 at time t2, the fuel ignited here also has a timing before time t1. In other words, the fuel has already been injected and has not been subjected to OT increase. Accordingly, if the ignition timing at the ignition (2) is corrected to be retarded, an increase in the fuel injection amount is insufficient with respect to the ignition timing that has been corrected for the retard.

  Also, for example, when ignition (3), which is the third ignition after the request for retarding, is performed in the fourth cylinder # 4 at time t3, the fuel ignited here is already injected at time t1. The fuel that was being executed (the fuel that was injected during the injection period (3) in which the injection was started before the time t1), and the fuel that has not been subjected to the OT increase. Therefore, if the ignition timing at the ignition (3) is corrected to be retarded, an increase in the fuel injection amount is insufficient with respect to the ignition timing that has been retarded.

  Further, for example, when ignition (4), which is the fourth ignition after the request for retarding, is performed at time t4, the fuel ignited here is also the fuel that has already been subjected to fuel injection at time t1. (The fuel injected in the injection period (4) in which the injection is started at the time before time t1), and the fuel for which the OT increase is not executed. Therefore, if the ignition timing at the ignition (4) is corrected to be retarded, the increase in the fuel injection amount is insufficient with respect to the ignition timing that has been corrected for the retard.

  In this regard, in the present embodiment, as described above, the above-described restriction process is executed in order to prevent the increase in the fuel injection amount from being insufficient with respect to the ignition timing that has been retarded. Therefore, for example, in the case of the example shown in FIG. 3, the injection period ETAU is 360 ° CA, so the retard hold setting number MSK is set to “4”. Accordingly, the ignition (1) in the first cylinder # 1 that is the first ignition after the request for retarding the ignition timing is made, and the third cylinder that becomes the second ignition after the request for retarding the ignition timing is made. Ignition in # 3 (2), ignition in No. 4 cylinder # 4 that becomes the third ignition after the ignition timing delay request is made (3), 4 after the ignition timing retardation request is made In the ignition (4) in the second cylinder # 2, which is the second ignition, the retardation request amount RR is set to “0”. Thereby, in the ignition (1), the ignition (2), the ignition (3), and the ignition (4), the retard correction of the ignition timing is suspended.

  Then, the ignition timing retardation correction is started from the ignition (5) in the first cylinder # 1 at time t5, which is the fifth ignition after the ignition timing retardation request is made. In the cylinders that are ignited after this ignition (5), the fuel increased by the OT increasing process is ignited. For example, the fuel ignited in the ignition (5) of the first cylinder # 1 is injected in the injection period (5) (period from time t1 to time t3) calculated based on the fuel amount increased by the OT increase process. This fuel has a fuel increase in time with respect to the ignition timing corrected in retard. Therefore, in the ignition after ignition (5), the effect of increasing the OT accompanying the correction of the ignition timing retardation is sufficiently obtained, and as a result, the excessive temperature rise of the catalyst 70 can be appropriately suppressed.

As described above, according to the present embodiment, the following effects can be obtained.
(1) When the fuel injection amount is increased and corrected in accordance with the ignition timing retardation request amount RR, for the cylinder that is predicted not to be in time for the fuel injection amount increase due to the increase correction with respect to the ignition timing retardation correction Therefore, the required retard amount RR for the ignition timing of the cylinder is limited to be smaller than the required retard amount RR corresponding to the retard request.

  More specifically, for a cylinder that is predicted not to be in time for increasing the fuel injection amount, the ignition timing is limited by limiting the retardation request amount RR to “0” until the fuel injection amount increases in time. The delay angle correction of is suspended.

  Therefore, an increase in the exhaust gas temperature due to the ignition timing retardation correction can be suppressed in a cylinder in which the fuel increase is not in time, thereby suppressing an excessive increase in the temperature of the catalyst 70 due to the ignition timing retardation. For example, heat damage to the catalyst 70 can be suppressed.

  (2) The number of times that the retard correction of the ignition timing is limited in accordance with the fuel injection period ETAU, that is, the above-described retard hold setting number MSK is set. Therefore, it is possible to appropriately predict a cylinder in which the increase in the fuel injection amount due to the increase correction is not in time for the retardation correction of the ignition timing.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, when limiting the ignition timing retard amount RR, the value is set to “0” so that the ignition timing is retarded without being implemented. In addition, when limiting the required retard amount RR of the ignition timing, the value of the required retard amount RR is not set to “0”, but is at least smaller than the required retard amount RR determined according to the required retard angle. You may restrict | limit so that it may become. Even in this case, the ignition timing retardation request amount RR is smaller than the original correction amount for the cylinder that is predicted not to be in time for the fuel injection amount increase due to the increase correction with respect to the ignition timing retardation correction. Therefore, it is possible to suppress an increase in the temperature of the catalyst 70 due to an excessive amount of retardation of the ignition timing with respect to the fuel injection amount.

  If the injection period ETAU cannot be sufficiently secured due to various factors, the injection period ETAU calculated in the above aspect is shortened to a period during which injection is possible, and the retardation is delayed according to the shortened injection period. The request amount RR may be limited. In this case, since the retardation required amount RR is also reduced in accordance with the shortened injection period, the decrease in the OT increase effect due to the shortened injection period can be compensated for by limiting the retardation required amount RR. Accordingly, in this case as well, it is possible to suppress the excessive temperature rise of the catalyst 70 due to the ignition timing retardation.

  For example, even if fuel injection that is immediately increased from the final ignition timing calculation timing calculated at 90 ° CA before the compression top dead center of each cylinder is started, the first injection can be injected. The maximum period is 810 ° CA. Therefore, an example in which the injection period ETAU cannot be sufficiently secured includes a case where the injection period ETAU is set to a value exceeding 810 ° CA.

  -Predict the delay angle at the time of shifting from the shift schedule of the automatic transmission 100, the engine speed NE, the engine load factor KL, and the like. When it is predicted that a delay angle request at the time of shifting will occur soon, the fuel injection amount increasing process (the OT increasing process) may be started prior to the ignition timing delay. In this case, when the ignition timing is retarded, the amount of fuel has already been increased, so that it is also possible to suppress the excessive temperature rise of the catalyst 70 due to the ignition timing retardation.

  -The retard timing request amount RR of the ignition timing is limited when there is a retard request at the time of shifting, but the retard request amount RR of the ignition timing is limited when there are other retard requests. It may be. Even in this case, the excessive temperature rise of the catalyst 70 due to the ignition timing retardation can be suppressed.

Although the execution timing of the limiting process and the calculation timing of the final ignition timing are 90 ° CA before compression top dead center, they may be changed to other timings.
Although the estimated temperature of the catalyst 70 is calculated based on the engine rotational speed NE, the engine load factor KL, etc., the estimated temperature of the catalyst 70 is calculated based on other parameters related to the engine operating state. Also good. For example, an exhaust temperature sensor that detects the exhaust temperature may be provided in the exhaust passage 15 and the estimated temperature of the catalyst 70 may be calculated based on the detected exhaust temperature. Further, the temperature of the catalyst 70 may be directly detected.

  The engine 1 is a so-called port injection type engine that injects fuel into the intake port 12. In addition, even in the case of a so-called in-cylinder injection type engine in which fuel is directly injected into the combustion chamber 8, the same problem as in the above embodiment can occur. Therefore, even in such an in-cylinder injection type engine, it is possible to obtain the operational effects according to the above-described embodiment by executing the restriction process described above.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Cylinder block, 3 ... Cylinder, 4 ... Piston, 5 ... Crankshaft, 6 ... Connecting rod, 7 ... Cylinder head, 8 ... Combustion chamber, 11 ... Spark plug, 12 ... Intake port, 13 ... Exhaust port , 14 ... intake passage, 15 ... exhaust passage, 16 ... injector, 17 ... intake valve, 18 ... exhaust valve, 31 ... intake side camshaft, 32 ... exhaust side camshaft, 33, 34 ... timing pulley, 35 ... timing belt 41 ... Crank angle sensor, 42a ... Cam angle sensor, 42b ... Cam angle sensor, 46 ... Igniter, 51 ... Surge tank, 52 ... Accelerator pedal, 53 ... Throttle valve, 54 ... Throttle opening sensor, 56 ... Air flow meter, 60a: Intake side variable valve mechanism (IN-VVT mechanism), 60b: Exhaust side variable valve mechanism (EX-) VT mechanism), 70 ... catalyst 80 ... controller, 100 ... automatic transmission.

Claims (1)

When there is a request for retarding the ignition timing, the ignition timing is retarded by the retard correction amount according to the retard request, and the fuel injection amount is increased by the retard correction amount. A control device,
For a cylinder that is predicted not to be in time for the fuel injection amount increase due to the increase correction with respect to the ignition timing retardation correction, the retardation correction amount of the ignition timing of the cylinder is retarded according to the retardation request. A control device for an internal combustion engine, characterized by being limited to be less than the amount.