JP2008196330A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that when required torque is reduced, actual VCT is shifted to a timing advance side with respect to a VCT target value and a combustion state is deteriorated as a result, due to response delay of a valve timing variable device capable of varying a relative rotating phase difference (VCT) of a cam shaft 42 with respect to a crank shaft 28 of a gasoline engine 10. <P>SOLUTION: When the required torque of the gasoline engine 10 is reduced, a combustion state achieved by the VCT target value obtained by a map operation is estimated. When the combustion state is not within a tolerance, feed forward correction of operation amount of an actuator used for output control of the gasoline engine 10 is performed, such as setting of the VCT target value to the timing delay side from the value obtained by the map operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device including target value setting means for setting a target value of an operation amount of a specific actuator among actuators for controlling an output of the internal combustion engine according to an operating state of the internal combustion engine. .

As is well known, when controlling an internal combustion engine, complicated control is performed to satisfy various requirements regarding output characteristics (output torque, exhaust characteristics, etc.) and fuel consumption. That is, based on the rotational speed and load of the internal combustion engine, the operation amounts of various actuators of the internal combustion engine are preliminarily adapted so as to optimize the injection amount, the charging efficiency, and the recirculation exhaust amount (EGR amount). Various actuators are operated based on the operation amount. Thereby, it becomes possible to satisfy various requirements for the internal combustion engine (Patent Document 1).
JP 2002-206456 A

  By the way, the adaptation of the operation amount of the actuator is basically performed so as to be an optimum value in a steady operation state of the internal combustion engine, but actually, it is restricted by the combustion state of the internal combustion engine at the time of transition. That is, when the actuator is operated with the optimum value in the steady operation state, the combustion state of the internal combustion engine may be out of the allowable range in the transient operation state of the internal combustion engine. For this reason, the operation amount is adapted so that the combustion state of the internal combustion engine is within the allowable range even in the transient operation state.

  However, in this case, since the operation amount of the actuator deviates from the optimum value in a steady state, it becomes an obstacle to improving the output characteristics of the internal combustion engine and reducing the fuel consumption.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to set a target value of an operation amount of a specific actuator among actuators for controlling an output of the internal combustion engine as an operating state of the internal combustion engine. It is an object of the present invention to provide a control device for an internal combustion engine that includes target value setting means for setting the target value in accordance with the target value.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to a first aspect of the present invention, target value setting means for setting a target value of an operation amount of a specific actuator among actuators for controlling an output of the internal combustion engine according to an operating state of the internal combustion engine, and the internal combustion engine Detection means for detecting a change in demand with respect to the operating state of the engine, and avoiding the combustion state of the internal combustion engine from deviating from an allowable range due to a response delay of the specific actuator when the change in demand is detected Therefore, it is characterized by comprising correction means for feedforward correcting the operation amount of at least one actuator for controlling the output of the internal combustion engine.

  In the above invention, in a situation where the combustion state of the internal combustion engine is assumed to be out of the allowable range due to a response delay of a specific actuator, at least one for controlling the output in order to make the combustion state within the allowable range. The operation amount of one actuator is feedforward corrected. For this reason, the setting of the target value by the target value setting means can be set to an optimum value in the steady state. That is, when setting the target value, if the optimum value in the steady state is taken into consideration when the transient is not taken into account, the combustion state in the transient may be out of the allowable range. By performing control based on setting of an operation amount different from that in the steady state, the target value can be adapted without considering the transition time.

  The correction target for the feedforward correction is preferably a command value (target value) for the operation amount of the actuator. As a result, the operation signal for the actuator can be appropriately feedforward corrected.

  According to a second aspect of the present invention, in the first aspect of the present invention, the input used by the target value setting means for setting the target value is operated according to a detection result of the detection means of the actuator. It includes a physical quantity that changes due to the operation of the object.

  In the above invention, the target value set by the target value setting means changes in accordance with the change in the physical quantity. For this reason, when the change rate of the physical quantity is large, the change rate of the target value also becomes large, and as a result, the influence of the response delay of a specific actuator may become significant.

  According to a third aspect of the present invention, in the second aspect of the present invention, the internal combustion engine is a spark ignition type internal combustion engine, and the actuator operated according to the detection result of the detection means is a flow path in the intake passage. It is a channel area adjusting means for adjusting the area, and the physical quantity is an intake air quantity of the internal combustion engine.

  In the above invention, the intake air amount may change abruptly depending on the changing speed of the flow path area adjusting means. For this reason, the target value set by the target value setting means may change abruptly according to the intake air amount, and there is a possibility that the response delay of a specific actuator becomes a problem.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the correction means includes means for reducing a change speed of the flow passage area by the flow passage area adjusting means for adjusting the flow passage area in the intake passage. It is characterized by.

  When the change speed of the flow path area by the flow path area adjusting means is large, the change speed of the target value set by the target value setting means also tends to increase. For this reason, in this case, there is a possibility that the delay of the actual operation amount with respect to the target value of the operation amount of the specific actuator may become remarkable, and the combustion state may deteriorate. In this regard, in the above-described invention, the change speed of the target value set by the target value setting means can be reduced by reducing the change speed of the channel area. For this reason, it can suppress suitably that the delay of the actual operation amount with respect to the target value of the operation amount of a specific actuator becomes remarkable, and it can avoid suitably that a combustion state remove | deviates from a tolerance | permissible_range. .

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the correction means compensates for a delay in a change in the output torque of the internal combustion engine accompanying a reduction in the change speed of the flow path area by correcting the ignition timing. It is characterized by further comprising means for performing.

  When the change speed of the flow passage area is reduced, the change speed of the output torque may be delayed because the change speed of the intake air amount is reduced. On the other hand, it is well known that the output torque changes when the ignition timing is changed. In the above invention, paying attention to this point and correcting the ignition timing, it is possible to suitably compensate for the delay in the change in the output torque caused by the reduction in the change speed of the flow path area.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, when the change in the demand is detected, the correction unit determines a target value of the operation amount of the specific actuator each time. Characterized by comprising a target value setting means at the time of transition that is set to a value on the side that is assumed to change with the change of the request from the value set by the target value setting means according to the operating state of To do.

  The operation amount of a specific actuator changes as its target value changes. And when a response delay arises in the actual operation amount of a specific actuator when a target value changes, there exists a possibility that a combustion state may remove | deviate from a tolerance | permissible_range due to this. Here, in the above invention, in such a situation, the target value of the manipulated variable is set by the target value setting means in accordance with a change in request, rather than the value set by the target value setting means in accordance with the driving state each time. Set the value on the side that is expected to change in the future. For this reason, compared with the case where the operation amount of a specific actuator is changed based on the value which a target value setting means sets according to each driving | running state, it becomes possible to change an operation amount rapidly. For this reason, it is possible to suitably suppress or avoid the actual operation amount of a specific actuator from being delayed with respect to the value set by the target value setting means in accordance with each operation state, and thus the combustion state is within an allowable range. Deviating from the above can be suitably avoided.

  According to a seventh aspect of the present invention, in the sixth aspect of the invention, the transient target value setting means predicts a value after the change of the target value associated with the change of the request, whereby the specific actuator The target value of the operation amount is set to the predicted value.

  In the above invention, the target value of the operation amount of the specific actuator when the request changes is set as a predicted value for the value after the change of the target value set by the target value setting means in accordance with the change of the request. For this reason, it can be avoided that the correction of the target value by the correcting means becomes excessive.

  The invention according to claim 8 is the valve characteristic variable according to any one of claims 1 to 7, wherein the specific actuator is configured to change a valve characteristic of at least one of an intake valve and an exhaust valve of the internal combustion engine. It is a device.

  When a delay occurs in the operation of the variable valve characteristic device, the combustion tends to become unstable due to the internal exhaust gas recirculation amount (internal EGR amount) recirculating into the combustion chamber of the internal combustion engine deviating from an appropriate value. For this reason, the said invention can show suitably the effect of a correction | amendment means.

  According to a ninth aspect of the present invention, in the eighth aspect of the invention, the intake valve and the exhaust valve of the internal combustion engine open and close in accordance with a rotation operation of a cam shaft that rotates in conjunction with the output shaft of the internal combustion engine. The valve characteristic varying device is characterized by comprising means for varying the relative rotational phase difference between the output shaft of the internal combustion engine and the cam shaft.

  When the relative rotational phase difference between the output shaft and the cam shaft is changed, a relatively large force is required, so that a large force is required for the valve characteristic variable device. The larger the force that can be generated by the variable valve characteristic device, the larger the variable valve characteristic device tends to be. On the other hand, there is always a demand for miniaturization of each member in the engine system. For this reason, the force that can be generated by the variable valve characteristic device is usually constrained by a demand for downsizing. Therefore, when the change speed of the target value set by the target value setting means is large, a response delay tends to occur in the operation amount adjusted by the valve characteristic variable device. For this reason, when the change of the said request | requirement is detected, there exists a possibility that a combustion state may remove | deviate from an allowable range. For this reason, the said invention can show | play especially suitably the effect of a correction | amendment means.

  According to a tenth aspect of the invention, in the invention according to any one of the first to ninth aspects, the correction means is realized by setting the target value by the target value setting means when a change in the request is detected. An estimation means for estimating the combustion state of the internal combustion engine, a determination means for determining whether or not the combustion state estimated by the estimation means is within an allowable range, and when it is determined that the combustion state is out of the allowable range And a means for feedforward correcting the operation amount of the at least one actuator so as to be within the allowable range.

  In the above invention, the correcting means can be appropriately configured by including the estimating means and the determining means.

  According to an eleventh aspect of the present invention, in the invention according to any one of the first to tenth aspects, the change in the request is a change in a required torque of the internal combustion engine.

  When the required torque changes, the operating state of the internal combustion engine is changed. For this reason, when the required torque changes, the operating state of the internal combustion engine also becomes a transient state, and the operation of a specific actuator tends to be changed. For this reason, there exists a possibility that a combustion state may remove | deviate from a tolerance | permissible_range due to the response delay of a specific actuator.

  A twelfth aspect of the invention according to the eleventh aspect of the invention is that, in the invention according to the eleventh aspect, the detection means detects a change in the required torque based on a detected value of an operation amount of an accelerator operation member.

  As a factor that increases the amount of change in the required torque and the change speed, the main cause is that caused by the operation of the accelerator operation member by the user. In this regard, in the above-described invention, by detecting a change in the required torque based on the detected value of the operation amount of the accelerator operation member by the user, it is possible to appropriately detect a situation in which the required torque changes rapidly.

  A thirteenth aspect of the invention is characterized in that in the invention of the internal combustion engine according to any one of the first to twelfth aspects, the change in the demand is a change to a reduction side of the demand torque of the internal combustion engine.

  When the required torque changes to the reduction side, if the manipulated variable remains at the value on the high torque side due to the delay of each actuator, the combustion state may be particularly lowered. For example, in the case where the specific actuator is a variable valve characteristic device as in the invention described in claim 8 above, the internal exhaust gas recirculation amount (internal Combustion tends to become unstable due to an increase in (EGR amount). For this reason, the said invention can show | play especially the effect by a correction | amendment means especially suitably.

(First embodiment)
Hereinafter, a first embodiment in which a control device for an internal combustion engine according to the present invention is applied to a control device for a gasoline engine will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the engine system according to the present embodiment.

  As shown in the figure, in a gasoline engine 10, a throttle valve 14 that adjusts the flow passage area in the intake passage 12 by adjusting the opening degree of the intake passage 12 by a DC motor or the like, and a throttle opening degree are detected. A throttle opening sensor 15 is provided. An air flow meter 13 for detecting the intake air amount is provided upstream of the throttle valve 14. On the other hand, a surge tank 16 is provided downstream of the throttle valve 14. The surge tank 16 is provided with an intake air temperature sensor 17. An electromagnetically driven fuel injection valve 18 for supplying and supplying fuel is attached downstream of the intake passage 12.

  The mixture of air and fuel in the intake passage 12 of the gasoline engine 10 is introduced into the combustion chamber 22 by opening the intake valve 20. An ignition plug 24 is attached to each cylinder of the cylinder head of the gasoline engine 10, and a high voltage is applied to the ignition plug 24 at a desired ignition timing through an ignition device (not shown) including an ignition coil. . By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 24, and the air-fuel mixture introduced into the combustion chamber 22 is ignited and used for combustion. The combustion energy is converted into rotational energy of the crankshaft 28 via the piston 26. Further, the air-fuel mixture subjected to combustion in the combustion chamber 22 is discharged to the exhaust passage 32 by the opening operation of the exhaust valve 30. A crank angle sensor 29 that detects the rotation angle of the crankshaft 28 is provided in the vicinity of the crankshaft 28.

  An exhaust gas recirculation passage 34 is provided between the surge tank 16 and the exhaust passage 32 in order to return a part of the exhaust gas to the intake passage 12. The exhaust gas recirculation passage 34 is provided with an EGR valve 36 made of an electromagnetic valve or the like. By adjusting the opening degree of the EGR valve 36, the exhaust amount (EGR amount) recirculated to the intake passage 12 through the exhaust recirculation passage 34 is adjusted.

  The intake valve 20 and the exhaust valve 30 are supplied with power from the crankshaft 28 and open and close with a cycle of two rotations of the crankshaft 28. However, in the present embodiment, the intake valve 20 and the exhaust valve 30 are connected to the crankshaft 28 via variable valve timing mechanisms 40a and 40b, respectively. For this reason, the opening timing of the intake valve 20 and the exhaust valve 30 with respect to the rotation angle of the crankshaft 28 can be made variable.

  Specifically, the power of the crankshaft 28 is transmitted to the camshaft 42 via the belt 43 and variable valve timing mechanisms 40a and 40b (hereinafter, variable valve timing mechanism 40). The variable valve timing mechanism 40 includes a first rotating body 44 that is mechanically connected to the crankshaft 28, and a second rotating body 46 that is mechanically connected to the camshaft 42. In the present embodiment, the second rotating body 46 includes a plurality of protrusions 46 a, and the second rotating body 46 is accommodated in the first rotating body 44. Then, the retard angle for retarding the relative rotation angle (rotation phase difference) of the cam shaft 42 with respect to the crankshaft 28 by the protrusion 46a of the second rotation body 46 and the inner wall of the first rotation body 44. A chamber 48 and an advance chamber 50 for advancing the rotational phase difference are partitioned.

  The variable valve timing mechanism 40 is hydraulically driven by the inflow and outflow of oil between the retard chamber 48 and the advance chamber 50. The oil inflow and outflow is adjusted by an oil control valve (OCV60).

  The OCV 60 supplies the oil in the oil pan 72 to the retard chamber 48 or the advance chamber 50 via the supply path 61 and the retard path 62 or the advance path 63 by the hydraulic pump 70. Further, the OCV 60 causes oil to flow out from the retard chamber 48 or the advance chamber 50 to the oil pan 72 via the retard path 62 or the advance path 63 and the discharge path 64. The flow path area between the retard path 62 or the advance path 63 and the supply path 61 or the discharge path 64 is adjusted by the spool 65. That is, the spool 65 is pushed to the left in the drawing by the spring 66, and a force toward the right in the drawing is applied by the electromagnetic solenoid 67. Therefore, it is possible to manipulate the displacement amount of the spool 65 by giving an operation signal to the electromagnetic solenoid 67 and adjusting the duty of the operation signal.

  Note that cam angle sensors 41a and 41b for detecting the rotation angle of the cam shaft 42 (actually, the intake cam shaft and the exhaust cam shaft) are provided in the vicinity of the variable valve timing mechanisms 40a and 40b.

  The engine system further includes an accelerator sensor 80 that detects an operation amount of the accelerator pedal 81.

  On the other hand, the electronic control unit (ECU 90) takes in the detection results of the various sensors and controls the output of the gasoline engine 10 based on the detection results. FIG. 2 shows a processing procedure of output control of the gasoline engine 10 when the accelerator pedal 81 is operated by the user. This process is repeatedly executed by the ECU 90, for example, at a predetermined cycle.

  In this series of processes, first, in step S100, a target value (target opening) of the opening of the throttle valve 14 corresponding to the detected value of the operation amount of the accelerator pedal 81 is calculated. Here, in view of the fact that the operation amount of the accelerator pedal 81 becomes a parameter expressing the torque requested by the user, the target opening degree is calculated so as to satisfy the required torque. For example, when performing torque base control, the target opening may be set by adding the torque required from the vehicle roll prevention control to the required torque calculated from the operation amount of the accelerator pedal.

  In the subsequent step S102, the throttle valve 14 is operated so that the opening degree of the throttle valve 14 becomes the target opening degree. In the subsequent step S104, the rotational speed based on the detection value of the crank angle sensor 29 and the air amount detected by the air flow meter 13 are acquired. In step S106, an air amount GN per rotation is calculated based on the rotation speed and the air amount. Actually, there is a difference due to the flow of air between the air flow rate in the vicinity of the air flow meter 13 and the air flow rate flowing into the combustion chamber 22, so that this difference is compensated by a known method. It is desirable that the air amount GN be an air amount per one rotation flowing into the combustion chamber 22.

  In the subsequent step S108, the target value (VCT target value) of the rotational phase difference VCT of the camshaft 42 with respect to the crankshaft 28 is calculated based on the rotational speed and the air amount GN. Here, as shown in FIG. 3, the VCT target value is map-calculated using a map that defines the relationship between the rotational speed and the air amount GN and the VCT target value. In practice, the map shown in FIG. 3 is composed of two different maps corresponding to the intake valve 20 and the exhaust valve 30, respectively. That is, in step S108, VCT target values for both the intake valve 20 and the exhaust valve 30 are calculated separately. In subsequent step S110, a detection value (actual VCT) of rotational phase difference VCT is acquired. Here, the actual VCT of the intake valve 20 and the exhaust valve 30 is detected based on the detection value of the crank angle sensor 29 and the detection values of the cam angle sensors 41a and 41b. In step S112, the OCV 60 is operated to control the actual VCT to the VCT target value. Here, for example, when the VCT target value changes, the actual VCT is feedback-controlled to the VCT target value by proportional control based on the difference between the actual VCT and the VCT target value, and when the VCT target value is in a steady state, the actual VCT The actual VCT may be feedback-controlled to the VCT target value by integral control based on the VCT target value.

  In the subsequent step S114, a target value for the ignition timing is calculated based on the air amount GN, the rotational speed NE, and the actual VCT. Here, for example, the target value of the ignition timing may be calculated using a three-dimensional map that defines the relationship between the air amount GN, the rotational speed NE, and the actual VCT and the target value of the ignition timing. In step S116, the spark plug 24 is operated so that the ignition timing is set to the target value.

  The map shown in FIG. 3 is adapted to optimize the output characteristics (output torque, exhaust characteristics, etc.) of the gasoline engine 10 and to minimize fuel consumption. This adaptation is basically set to a value for optimizing the output characteristics of the gasoline engine 10 in a steady state. That is, for example, as illustrated in FIG. 4, the VCT target value is adapted so that the output torque becomes maximum within a range where the combustion stability does not exceed the allowable upper limit value. Here, the combustion stability is an amount determined by the percentage of the standard deviation of the average value (average effective pressure) per combustion cycle of the pressure in the combustion chamber 22 (in-cylinder pressure) with respect to the average value of a plurality of sampling values Pi. The smaller the value is, the more stable the operation state is.

  However, in this case, there is a possibility that the output characteristics cannot be kept good in the transient state of the gasoline engine 10. This will be described below.

  FIG. 5 shows the relationship between the actual VCT of the intake valve 20, torque, and combustion stability. As shown in the figure, as the actual VCT advances, the value of the combustion stability increases (combustion becomes unstable), approaches the allowable upper limit value, and eventually exceeds this value. On the other hand, the torque gradually increases as the actual VCT is advanced, and then gradually decreases. Here, the torque gradually increasing by advancing the actual VCT is due to a decrease in pumping loss or the like. On the other hand, when the actual VCT is advanced to some extent, the torque gradually decreases because the combustion becomes unstable and the frequency of misfire increases. For this reason, it is desirable to set the actual VCT so that the torque becomes the maximum value within the range where the combustion stability is within the allowable upper limit value.

  By the way, the combustion stability and torque change according to the load (required torque, air amount GN, etc.). That is, as the load becomes lower, the actual VCT whose combustion stability becomes the allowable upper limit shifts to the retard side. Further, the actual VCT at which the torque becomes maximum also shifts to the retard side. For this reason, when the operating state of the gasoline engine 10 shifts from a high load to a low load, the optimum value of VCT also shifts to the retard side. For this reason, the VCT target value is set to a retarded value as the load is low.

  Here, when the operation state of the gasoline engine 10 changes rapidly from the high load operation state to the low load operation state, the VCT target value also changes rapidly to the retard side. However, even if the OCV 60 is operated so that the actual VCT follows the VCT target value, it takes time until the actual VCT actually follows the VCT target value, and a response delay may occur. Here, when the VCT target value is adapted so as to maximize the torque generated in a range where the combustion stability is less than or equal to the allowable upper limit value in the steady state, the VCT target value changes rapidly as shown in FIG. When the actual VCT is performed, the combustion stability may exceed the allowable upper limit value because the actual VCT is more advanced than the VCT target value. FIG. 6A shows the change in the amount of operation of the accelerator pedal, FIG. 6B shows the change in the actual opening of the throttle valve 14 with a solid line, and shows the change in the target opening with a one-dot chain line. Show. FIG. 6C shows the transition of the air amount GN, FIG. 6D shows the transition of the actual VCT with a solid line, and the transition of the VCT target value with a one-dot chain line. Further, FIG. 6 (e) shows the transition of the ignition timing, FIG. 6 (f) shows the actual torque by the solid line, and the transition of the required torque according to the operation amount of the accelerator pedal by the one-dot chain line. .

  As shown in the drawing, when the required torque decreases due to abrupt release of the accelerator pedal 81, first, the target opening of the throttle valve 14 decreases rapidly (the target value of the flow path area of the intake passage 12 increases abruptly). Decrease). As a result, the actual opening of the throttle valve 14 decreases. When the opening degree of the throttle valve 14 decreases, the air amount GN decreases. As the air amount GN decreases, the VCT target value shifts to the retard side. Here, the changing speed of the VCT target value is substantially determined by the changing speed of the air amount GN. This is because the change in the rotational speed NE accompanying the operation of the accelerator pedal 81 is slower than the change in the air quantity GN, although the VCT target value is set by the rotational speed NE and the air quantity GN. . When the VCT target value suddenly changes to the retard side, the actual VCT is on the more advanced side than the VCT target value due to a response delay of the valve timing variable mechanism 40. For this reason, the exhaust gas (internal EGR) that flows backward from the exhaust passage 32 to the combustion chamber 22 at the time of overlap of the valve opening period of the intake valve 20 and the exhaust valve 30 increases, and as a result, the combustion may become unstable. That is, in the transient operation state in which the VCT target value changes to the retard side, as shown in FIG. 7, the EGR rate when the combustion stability becomes the allowable upper limit value (the amount of internal EGR with respect to the gas in the combustion chamber 22). Ratio). In this case, when the misfire or the like occurs, the torque temporarily decreases as shown in FIG.

  FIG. 8 shows a simulation result of an increase in the EGR rate when the required torque is rapidly reduced and the occurrence of misfire associated therewith. Specifically, FIG. 8A shows the transition of the load factor, which is the ratio of the actual air amount GN to the maximum value of the air amount GN at each rotational speed. 8 (b) and 8 (c), the transition of the actual VCT on the intake side and the exhaust side is shown by a solid line, and the transition of the VCT target value is shown by a one-dot chain line. FIG. 8 (d) shows the transition of the output torque, and FIG. 8 (e) shows a solid line that is determined according to the combustion pressure for the torque generated by combustion in the gasoline engine 10 (torque shown). The transition of the indicated torque when the optimum combustion state is realized is shown by a one-dot chain line. In FIG. 8 (f), the solid line shows the transition of the actual EGR rate, the one-dot chain line shows the transition of the ideal EGR rate, and the two-dot chain line shows the EGR rate at which combustion does not become unstable. Indicates the critical value.

  As shown in the figure, the EGR rate exceeds the critical value because the actual VCT is delayed with respect to the VCT target value. As a result, combustion deteriorates and misfire occurs, and the indicated torque and output torque (shaft torque) are excessively reduced.

  On the other hand, when the VCT target value is adapted so that the combustion stability does not exceed the allowable upper limit regardless of the actual VCT response delay when the VCT target value changes, the steady state where the VCT target value does not change. In this case, the output characteristics of the gasoline engine 10 cannot be maximized or the fuel consumption cannot be minimized.

  Therefore, in the present embodiment, when the required torque decreases, in order to avoid the combustion state from deviating from the allowable range due to the response delay of the valve timing variable device (the valve timing variable mechanism 40 and the OCV 60), FIG. The feed-forward correction is performed on the output control mode shown in (1). Specifically, as shown in FIG. 9, feedforward correction for reducing the change rate of the target opening of the throttle valve 14 is performed. Here, FIG. 9A to FIG. 9F correspond to the previous FIG. 6A to FIG. 6F.

As shown in the figure, the rate of change of the target opening degree of the throttle valve 14 is reduced, so that the rate of decrease of the air amount GN is reduced, so the rate of change of the VCT target value is also reduced. For this reason, the followability of the actual VCT with respect to the VCT target value is improved. For this reason, the internal EGR rate at the time of transition in which the VCT target value changes does not exceed the limit value shown in FIG. For this reason, even if the VCT target value is adapted to the optimum value in the steady state, the combustion state at the time of transition can be within the allowable range. Hereinafter, with regard to the specific processing of the feedforward correction, (a) processing related to estimation of the combustion state at the time of transition, and (b) switching of the output control mode when it is determined that the combustion state is out of the allowable range. This process will be described in detail in the order of (c) the feedforward correction process.
<(A) Processing related to estimation of combustion state during transition>
FIG. 10 shows a processing procedure for estimating the combustion state at the time of transition. This process is repeatedly executed by the ECU 90, for example, at a predetermined cycle.

  In this series of processing, first, in step S10, based on the detection value of the accelerator sensor 80, it is determined whether or not the amount of change in the output torque of the gasoline engine 10 with respect to the operation amount of the accelerator pedal 81 exceeds the determination value. To do. This process is based on the amount of operation of the accelerator pedal 81, and there is a concern that the combustion state of the gasoline engine 10 may become unstable due to the actual VCT shifting toward the advance side with respect to the VCT target value. It is temporarily determined whether or not there is. The determination value is set according to the amount of change that causes a concern that the combustion state of the gasoline engine 10 may become unstable.

  In the subsequent step S12, the target opening degree of the throttle valve 14 corresponding to the operation amount of the accelerator pedal is estimated (calculated). This process is for estimating how the target opening of the throttle valve 14 changes in accordance with the change in the operation amount of the accelerator pedal 81 detected in step S10. Here, for example, when torque-based control is performed, the change in the required torque is grasped from the change in the operation amount of the accelerator pedal 81, and the required torque is determined based on the relationship between the required torque and the target opening of the throttle valve 14. What is necessary is just to estimate the change of the target opening according to a change. When changing the target opening according to the change in the required torque, for example, when performing a relaxation process that relaxes the change in the target opening by weighted average processing, etc., the time change of the target opening due to the relaxation process is predicted. It is desirable to do.

  In the subsequent step S14, the response delay of the actual opening with respect to the change in the target opening of the throttle valve 14 is estimated based on the dynamic characteristics of the throttle valve 14. In other words, the behavior of the throttle valve 14 is estimated. This process can be performed using a dynamic characteristic model of the throttle valve 14. As this model, for example, a model in which dead time is added to the first-order delay may be used.

  In the subsequent step S16, the time change of the air amount GN according to the behavior of the throttle valve 14 estimated in step S14 is estimated. This processing may be performed based on a model (physical model or the like) corresponding to the structure of the intake passage 12 and the opening of the throttle valve 14, for example. At this time, it is desirable to include the detected value of the intake air temperature sensor 17, the rotational speed, etc., in addition to the estimated value of the opening degree of the throttle valve 14, as the input parameters of this physical model.

  In the subsequent step S18, the time change of the VCT target value is estimated using the map shown in FIG. 3 based on the air amount GN estimated in step S16 and the rotational speed. Here, the current actual rotational speed is used as the rotational speed in view of the fact that the responsiveness of the rotational speed change accompanying the change of the accelerator pedal 81 is slower than the responsiveness of the change in the air amount GN. For this reason, the VCT target value changes according to the time-series data of the estimated air amount GN.

  In the subsequent step S20, the behavior of the actual VCT corresponding to the VCT target value estimated in step S18 is estimated. Here, the behavior of the actual VCT may be estimated based on the dynamic characteristic model of the valve timing variable device. As this dynamic characteristic model, for example, a model in which dead time is added to the first order delay may be used.

  In subsequent step S22, the air amount GN estimated in step S16, the actual VCT estimated in step S20, and the current rotation speed are input, and the same process as in step S114 of FIG. 2 is performed. Estimate the target value of the ignition timing. For example, when the target value is set using the three-dimensional map in step S114 of FIG. 2, the target value may be estimated using the same three-dimensional map.

  In the subsequent step S24, the actual ignition timing is estimated in consideration of the response delay of the operation of the spark plug 24. In view of the fact that the response delay of the operation of the spark plug 24 is normally negligible, the estimated value of the actual ignition timing may be set as the target value estimated in step S24.

  In subsequent step S26, a value in a transient state of a parameter (combustion state parameter) for quantifying the combustion state is estimated. Here, the combustion state parameters include exhaust characteristics, torque, torque fluctuation, combustion stability, and the like. The transient combustion state may be a combustion state from when the required torque is changed by operating the accelerator pedal 81 until the actual VCT converges to a value corresponding to the required torque. For the estimation of the combustion state parameter, the estimated value of the air amount GN, the estimated value of the actual VCT, the estimated value of the ignition timing, and the current rotation speed are used. However, in order to estimate the above parameters with higher accuracy, the air / fuel ratio, EGR amount, injection amount, etc. at the time of transition may be estimated, and the above parameters may be estimated using these estimated values together.

  Here, the air-fuel ratio at the time of transition may be estimated from a target air-fuel ratio determined from the operating state of the gasoline engine 10 and a physical model. That is, during the transition, the actual air-fuel ratio cannot be set to the target air-fuel ratio by the air-fuel ratio feedback control, so that the fuel injected from the fuel injection valve 18 adheres to the intake passage 12 and burns into the combustion chamber 22. What is necessary is just to estimate by the quantity etc. which are not supplied to a physical model. Further, regarding the EGR amount, in consideration of the opening degree of the EGR valve 36 being set according to the rotational speed and the air amount GN, the temporary opening degree of the EGR valve 36 is determined by the estimated value of the air amount GN and the rotational speed. The actual opening degree of the EGR valve 36 is estimated in consideration of the response delay based on the dynamic characteristic model of the EGR valve 36. Based on the opening degree of the EGR valve 36 estimated in this way, the EGR amount is estimated by using a model for the exhaust gas recirculation mode in the exhaust gas recirculation passage 34. The injection amount is estimated based on the estimated value of the air amount GN and the target air-fuel ratio estimated by the control logic of the ECU 90.

  The combustion state parameter may be estimated by, for example, a statistical model based on the estimated values and the rotation speed. That is, for example, when the combustion parameter is combustion stability, a map that defines the relationship between the actual VCT and the combustion stability is prepared for each air amount GN based on the relationship shown in FIG. What is necessary is just to prepare the map etc. which determine the relationship between a time and combustion stability, and estimate final combustion stability by the weighted average value of each combustion stability value calculated by these. Instead of this, it may be estimated by a physical model using the above estimated values or the like.

In a succeeding step S28, it is determined whether or not the combustion state is within an allowable range. Here, for example, it may be determined whether or not the estimated value of the combustion stability is equal to or less than the allowable upper limit value. If it is determined that the combustion state is out of the allowable range, a combustion deterioration determination counter indicating that the combustion state is estimated to be deteriorated is set to a predetermined value in step S30.
<(B) Processing for switching output control mode>
The predetermined value temporarily determines a period during which it is assumed that it is appropriate to correct the control mode shown in FIG. 2 by the feedforward correction process. That is, as shown in FIG. 11, when the combustion deterioration determination counter is not zero (step S40: NO), the combustion deterioration determination counter is decremented at a predetermined cycle (step S42). Therefore, depending on the decrement speed and the predetermined value, A provisional period during which it is assumed that the above correction is appropriate can be determined. Then, as shown in FIG. 12, while the combustion deterioration determination counter is larger than zero (step S50: YES), the feedforward correction control is performed (S200). Normal output control is performed (step S100).
<(C) Feedforward correction process>
FIG. 13 shows the procedure of the feedforward correction process. This process is repeatedly executed by the ECU 90, for example, at a predetermined cycle.

  In this series of processing, in step S200, the target opening of the throttle valve 14 corresponding to the operation amount of the accelerator pedal 81 is calculated in the same manner as the processing in step S100 of FIG. In the subsequent step S202, the amount of change in the target opening of the throttle valve 14 is calculated. In step S204, it is determined whether or not the amount of change in the throttle valve 14 exceeds a reference value. This process determines whether or not the change rate of the target opening is so fast that it is assumed that the deterioration of the combustion state due to the response delay of the valve timing variable device is remarkable. If it is determined that the amount of change in the target opening exceeds the reference value, the target opening is set in step S206 so that the amount of change in the target opening is within the reference value. Here, the current target opening may be a value obtained by correcting the previous target opening by reducing the reference value. According to the processes in steps S204 and S206, the changing speed of the target opening is limited to a speed determined by the processing cycle and the reference value in FIG. Thereby, compared with the case where it does not correct | amend, the change speed of the throttle valve 14 can be reduced, and the change of the air quantity GN can be relieved by extension. For this reason, the change speed of the VCT target value is reduced, and the response delay of the actual VCT can be reduced.

  When the process of step S206 is completed, the same processes as steps S102 to S116 of FIG. 2 are performed in steps S208 to S222.

  Note that, depending on the time required to determine whether there is combustion deterioration by the process shown in FIG. 10, there is a possibility that the process of reducing the target opening change rate in FIG. 13 cannot be performed appropriately. Therefore, in such a case, the processes in steps S200 to S206 in FIG. 13 are always performed, and the control in FIG. 13 may be validated when step S200 is selected in step S50 in FIG. Further, as the operation amount of the accelerator pedal 81, different parameters may be used in the previous FIG. 10 and FIG. That is, since noise is mixed in the output of the accelerator sensor 80, the final accelerator pedal 81 is usually subjected to a relaxation process for reducing the change by a weighted average process or a moving average process. The amount of operation. Here, if the process of FIG. 10 is performed using the value subjected to the second relaxation process with a small relaxation degree or the value before the relaxation process, it is possible to more quickly estimate the presence or absence of combustion deterioration.

  FIG. 14 shows an aspect of the feedforward correction process of the output control of the gasoline engine 10 by the above process. Specifically, FIG. 14 (a) shows the change in the opening of the throttle valve 14, FIG. 14 (b) shows the change in the load factor, and FIG. 14 (c) shows the change in the actual VCT on the intake side. FIG. 14D shows the transition of the output torque of the gasoline engine 10. In FIG. 14, the solid line indicates the characteristic in the present embodiment, and the two-dot chain line indicates the characteristic when the feedforward correction is not performed in a situation where the required torque rapidly decreases. Moreover, what is shown with a dashed-dotted line in FIG.14 (c) has shown transition of the VCT target value about both this embodiment and the case where feedforward correction | amendment is not performed.

  As shown in the figure, the change in the load factor (air amount GN) is alleviated by reducing the changing speed of the throttle valve 14. For this reason, the change speed of the VCT target value is reduced, and the follow-up delay of the actual VCT with respect to the VCT target value can be reduced. Here, the VCT target value is adapted to optimize the combustion state in each operation state. For this reason, if the actual VCT follows the VCT target value, it is considered that the combustion state can be improved. Therefore, by reducing the follow-up delay of the actual VCT, it is possible to suppress or avoid the deterioration of combustion, and it is possible to avoid an excessive drop in the output torque of the gasoline engine 10. This excessive decrease in output torque is considered to be caused by misfire.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) To control the output of the gasoline engine 10 in order to avoid that the combustion state of the gasoline engine 10 deviates from the allowable range due to a response delay of the variable valve timing device when a change in the required torque is detected. The feed amount was corrected for the operation amount of the actuator. As a result, the VCT target value can be adapted without considering the transition, so that the VCT target value can be set to an optimum value in the steady state. Thereby, fuel consumption can be reduced.

  (2) The air quantity GN which is a physical quantity that changes due to the operation of the throttle valve 14 is included in the input parameters for setting the VCT target value. As a result, the VCT target value changes according to the change in the air amount GN. For this reason, a reliable effect can be expected by the feedforward correction described above.

  (3) Feedforward correction was performed by reducing the changing speed of the throttle valve 14. Thereby, the change rate of the VCT target value can be reduced. For this reason, it is possible to reduce the follow-up delay of the actual VCT with respect to the VCT target value, and thus it is possible to preferably avoid the combustion state from deviating from the allowable range.

  (4) A variable valve timing device for changing the valve characteristics of the intake valve 20 and the exhaust valve 30 of the gasoline engine 10 is provided, and these VCT target values are optimized in a steady state. In this case, since the internal EGR rate deviates from an appropriate value, the combustion is likely to become unstable, so that the effect of feedforward correction can be suitably achieved.

  (5) In the variable valve timing device, the relative rotational phase difference between the crankshaft 28 and the camshaft 42 of the gasoline engine 10 is variable. For this reason, when the rotational phase difference is changed, a relatively large force is required, and thus a large force is required for the valve timing variable device. Here, the larger the force that can be generated by the variable valve timing device, the larger the variable valve timing device tends to be. On the other hand, there is always a demand for miniaturization of each member in the engine system. For this reason, when the change rate of the VCT target value is large, a response delay is likely to occur in the operation amount adjusted by the variable valve timing device. For this reason, when the change of the said request | requirement is detected, there exists a possibility that a combustion state may remove | deviate from an allowable range. For this reason, the said invention can show | play especially the effect of feedforward correction | amendment especially suitably.

  (6) A process for estimating the combustion state of the gasoline engine 10 realized by setting the VCT target value, a process for determining whether or not the estimated combustion state is within the allowable range, and a determination that it is out of the allowable range When the operation is performed, a process of feedforward correcting the operation amount of the actuator for output control so as to be within the allowable range is performed. Thereby, feedforward correction can be performed appropriately.

  (7) The change in the required torque is detected based on the detected value of the operation amount of the accelerator pedal 81. As a result, it is possible to appropriately detect a situation in which the required torque changes rapidly.

  (8) The change of the required torque of the gasoline engine 10 toward the reduction side was handled as the change of the required torque. When the required torque changes to the reduction side, if the manipulated value remains at the value on the high torque side due to the valve timing delay, the combustion state may be particularly lowered. For this reason, the effect by the said feedforward correction can be show | played especially suitably.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  According to the first embodiment, although the instability of combustion can be suppressed or avoided by reducing the change rate of the target opening degree of the throttle valve 14, the change rate of the air amount GN is reduced. As a result, the output torque decreases at a reduced rate. For this reason, the followability to the required torque is deteriorated. Therefore, in the present embodiment, as shown in FIG. 15, in addition to the process of reducing the changing speed of the target opening of the throttle valve 14, the ignition timing is retarded. 15A to 15F correspond to the previous FIGS. 9A to 9F. In particular, FIG. 15E shows the corrected ignition timing by a solid line, the ignition timing before the correction by a broken line, FIG. 15F shows the output torque by the ignition timing correction by a solid line, and the broken line The transition of the output torque when the ignition timing is not corrected is shown. As shown in the figure, by correcting the ignition timing by retarding, the output torque can be reduced as compared with the case where the ignition timing is not corrected. For this reason, it can compensate suitably that the fall speed of the output torque decreases due to the change speed of the air amount GN decreasing.

  FIG. 16 shows a processing procedure for feedforward correction according to the present embodiment. This process is repeatedly executed by the EUC 90, for example, at a predetermined cycle. In FIG. 16, the same processes as those shown in FIG. 13 are given the same reference numerals for the sake of convenience.

  In this series of processes, when the process of step S220 shown in FIG. 13 is completed, in step S230, the amount of increase in the air amount GN resulting from reducing the change rate of the target opening of the throttle valve 14, that is, Then, the difference between the air amount GN and the air amount GN when the change rate is not reduced is calculated. Here, the air amount GN when the change rate is not reduced is calculated by the process of step S16 of FIG. For this reason, in step S230, the air amount GN in the case where processing is performed using the change in the target opening as a reference value by making an affirmative determination in step S204 is the same as the processing in step S16 in FIG. And the difference between these estimated values is calculated.

  In the subsequent step S232, the torque increase amount is calculated from the air amount increase amount, that is, the difference in torque when the target opening degree change rate is not reduced. Here, for example, in the same manner as the process of step S114 of FIG. 2, the map calculation is performed by inputting the air amount increase amount, the rotational speed, the target air-fuel ratio, etc. under the assumption that the ignition timing is set. The amount of torque increase may be calculated. In the subsequent step S234, the required amount A1 of the ignition timing correction amount is calculated based on the relationship between the ignition timing and the torque characteristics. Here, for example, the required amount A1 may be map-calculated with the air amount GN and the amount of increase in torque and the air-fuel ratio (and the ignition timing before correction) as inputs. This map shows that when the air amount GN and the air-fuel ratio of the gasoline engine 10 are constant, the output torque efficiency (the ratio of the output torque at each ignition timing to the output torque at a predetermined ignition timing) depends on the ignition timing. Created in view of what will be determined. That is, since the output torque at a predetermined ignition timing is determined by the air amount GN and the air / fuel ratio, the output torque is determined based on the air amount, the air / fuel ratio, and the ignition timing. This means that the ignition timing is determined from the air amount, the air-fuel ratio, and the torque. Therefore, based on the air amount GN, the air-fuel ratio, and the torque, the required amount A1 of the ignition timing correction amount for correcting the torque increase amount can be calculated. The required amount A1 is set to a larger value as it is on the retard side.

  In the subsequent step S236, a range (allowable value A2) in which retardation correction is allowed to ensure combustion stability is calculated. Here, for example, a map may be created by previously matching the relationship between the air amount GN, the rotation speed, the actual VCT, and the like and the allowable value A2, and calculation may be performed using this map. In a succeeding step S238, it is determined whether or not the required amount A1 is larger than the allowable value A2. When it is determined that the value is equal to or smaller than the allowable value A2, the ignition timing target value SA is retarded by the required amount A1 in step S240. On the other hand, when it is determined in step S238 that it is larger than the allowable value A2, the target value SA is retarded by the allowable value A2 in step S242. When the processes in steps S240 and S242 are completed, the process in step S222 shown in FIG. 2 is performed.

  FIG. 17 shows the transition of the indicated torque by the feedforward correction. Specifically, in the figure, a solid line indicates the transition of the indicated torque by the feedforward control according to the present embodiment, a one-dot chain line indicates a transition of the indicated torque according to the first embodiment, and a broken line indicates any feed. The transition of the indicated torque when forward correction is not performed is shown. As shown in the figure, when the normal output control shown in FIG. 2 is performed without feedforward correction, the indicated torque can be quickly reduced according to the required torque, but combustion is not possible. Stabilizes and excessive torque drops due to misfire. In the first embodiment, although the combustion is stable, the decrease rate of the indicated torque is delayed, so that it is not possible to quickly cope with the decrease in the required torque. For this reason, the user cannot obtain a feeling of deceleration, and drivability deteriorates. On the other hand, in this embodiment, since the ignition timing is corrected, the rate of decrease in the output torque can be set to the same level as in the case of performing the normal output control shown in FIG. Moreover, instability of combustion can be avoided.

  According to this embodiment described above, in addition to the effects (1) to (8) of the first embodiment, the following effects can be obtained.

  (9) A decrease in the changing speed of the output torque of the gasoline engine 10 accompanying a reduction in the changing speed of the throttle valve 14 was compensated by correcting the ignition timing. Thereby, a feeling of deceleration can be ensured when the accelerator pedal 81 is released.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, when the combustion deterioration determination counter is set, the VCT target value is set in advance of the retarded side from the value determined from the map shown in FIG. 3 according to each operation state. FIG. 18 shows a form of feedforward correction according to this embodiment. 18A to 18F correspond to the previous FIG. 6A to FIG. 6F.

  As shown in the figure, when the required torque is reduced by releasing the accelerator pedal 81, before the air amount GN is reduced accordingly, as shown by a one-dot chain line in FIG. Set the VCT target value to the retard side. As a result, as indicated by a solid line in FIG. 18D, the actual VCT shifts to the retard side from the beginning when the accelerator pedal 81 is released regardless of whether the air amount GN is decreased. For this reason, compared with the case where the feedforward correction shown with the broken line in FIG.18 (d) is not performed, real VCT can be operated to a retard angle side rapidly.

  FIG. 19 shows a processing procedure for feedforward correction according to the present embodiment. This process is repeatedly executed by the ECU 90, for example, at a predetermined cycle. In FIG. 19, the same steps as those shown in FIG. 13 are given the same step numbers for the sake of convenience.

  In this series of processes, when the process of step S212 in FIG. 13 is completed, the VCT target value is forcibly set to the retard side in step S250 by comparing with the value determined by the process shown in FIG. Perform the setting process. Specifically, the VCT target value is set to the final value determined by the required torque for the VCT target value estimated in step S18 of FIG. 10, that is, the convergence value after the change of the VCT target value. Except for this process, the process is the same as the process shown in FIG. 13 except that there is no process for limiting the change rate of the target opening.

  According to this embodiment described above, in addition to the effects (1), (2) and (4) to (8) of the first embodiment, the following effects can be obtained. .

  (10) When the required torque is reduced, the VCT target value is set to a value on the retard side from the value set by the map shown in FIG. 3 according to each operation state. Thereby, it can be suitably avoided that the actual VCT is excessively advanced with respect to the VCT target value set by the map shown in FIG.

  (11) The value after the change of the VCT target value is predicted, and the VCT target value is set to a predicted value. Thereby, it is possible to avoid the feedforward correction of the VCT target value from being excessively retarded.

(Fourth embodiment)
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 20 shows a processing procedure for feedforward correction according to the present embodiment. This process is repeatedly executed by the ECU 90, for example, at a predetermined cycle. In FIG. 20, processes corresponding to the processes shown in FIG. 13 are given the same step numbers for convenience.

  As shown in the figure, in the present embodiment, the target opening degree changing speed limiting process in the previous first embodiment, and the VCT target value setting process to the retard side in the previous third embodiment, Do both. Thereby, combustion can be stabilized while relaxing the restriction degree of the target opening.

  According to the present embodiment described above, in accordance with the effects (1) to (8) of the previous first embodiment and the effects (10) and (11) of the previous third embodiment. In addition to the above effects, the following effects can be obtained.

  (12) In addition to the process of limiting the change rate of the target opening, the degree of restriction of the change rate of the target opening can be relaxed by performing feedforward correction to the retard side of the VCT target value. For this reason, the fall of the reduction | decrease rate of the air quantity GN can be suppressed.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  -You may combine the said 2nd Embodiment and 3rd Embodiment.

  In each of the above embodiments, the combustion state is estimated, and it is determined whether or not this is within the allowable range. This means that it is possible to determine whether or not the transient combustion state falls within the allowable range by using the parameter used for estimating the combustion state as an input. For this reason, a map for selecting one of the two logical values corresponding to whether or not the transient combustion state exceeds the allowable range from the parameters used for the above estimation is created, thereby deteriorating the combustion state. The presence or absence of may be judged. According to such a setting, the time required for the determination is shortened. Therefore, for example, a process that requires quick start of feedforward correction, such as a process of limiting the change rate of the target opening, is particularly effective. is there.

  In the previous second embodiment, the amount of increase in the air amount GN is obtained based on the degree of restriction on the amount of change in the target opening, and the ignition timing retardation correction amount is calculated therefrom. However, the present invention is not limited to this. For example, the ignition timing retardation correction amount may be map-calculated based on the driving state of the gasoline engine 10 (for example, the operation amount of the accelerator pedal 81, the rotational speed, and the actual VCT). According to this, it is possible to quickly perform feedforward correction at the time of transition requiring quick control.

  In the previous third embodiment, the VCT target value is set to the convergence value after the end of the transient state. However, the present invention is not limited to this. For example, it may be a value that is retarded by a predetermined amount from the value determined from the map shown in FIG. Even during the transition, the actual VCT is set to the VCT target value determined by the map shown in FIG. 3 in accordance with each operation state (rotational speed and air amount GN) to optimize combustion. This is considered desirable. For this reason, it is desirable to determine the amount of retarding based on the dynamic characteristics of the variable valve timing device so that the actual VCT becomes the VCT target value determined from each operating state.

  -The change in the required torque is not limited to the reduction side, but may be the increase side. Even in this case, in order to optimize the combustion state at the time of transition, it is effective to perform feedforward correction on the operation amount of the actuator for the normal output control. This can be realized, for example, by changing the VCT target value ahead of the value determined by the map shown in FIG. 3 in the third embodiment.

  The actuator that causes deterioration of the combustion state in the transient state due to dynamic characteristics is not limited to the hydraulically driven valve timing variable device. For example, even in a valve timing variable device that makes the relative rotational phase difference between the crankshaft 28 and the camshaft 42 variable by an electric motor, the motor tends to increase in size when the responsiveness is improved. This contradicts the demand for miniaturization of equipment. For this reason, even in this case, since the responsiveness tends to be a problem, the application of the present invention is effective.

  In addition, not only those that make the valve timing variable, but those that make the valve characteristics variable, such as those that make the valve lift variable, in short, the combustion state deteriorates due to the response delay. Therefore, the application of the present invention is effective. Further, not limited to the variable valve characteristic device, for example, an EGR valve 36 or the like, that is, among actuators that control the output of the gasoline engine 10, the target value according to the operating state (for those that perform open loop control, Anything may be used as long as it sets an operation amount).

  The method for detecting the change in the required torque is not limited to using the detection value of the accelerator sensor 80 that detects the operation amount of the accelerator pedal 81. For example, when cruise control that automatically controls the traveling speed (vehicle speed) of the vehicle to a constant speed is performed, the required torque calculated when the vehicle speed is controlled may be detected.

  -The change in the request for the operating state of the internal combustion engine is not limited to the change in the required torque. For example, it may be a change in demand for exhaust characteristics.

  The internal combustion engine is not limited to the intake port type spark ignition type internal combustion engine such as the gasoline engine 10, but may be a cylinder injection type spark ignition type internal combustion engine, or a compression ignition such as a diesel engine, for example. An internal combustion engine may be used.

The figure which shows the whole structure of the engine system concerning 1st Embodiment. The flowchart which shows the process sequence of the normal output control concerning the embodiment. The figure which shows the map for setting a VCT target value. The figure explaining the adaptation method of a VCT target value. The figure which shows the relationship between combustion stability and torque, and VCT. The time chart which shows the problem in the case of applying the output control in normal time at the time of transition. The figure explaining the problem in the case of applying the output control in normal time at the time of transition. The time chart which shows the problem in the case of applying the output control in normal time at the time of transition. The time chart which shows the aspect of the output control at the time of the transition concerning the said embodiment. The flowchart which shows the procedure of the estimation process of the combustion state at the time of the transition concerning the embodiment. The flowchart which shows the counting method of the combustion deterioration determination counter concerning the embodiment. The flowchart which shows the procedure of the switching process of the aspect of the output control concerning the embodiment. The flowchart which shows the procedure of the feedforward correction process of the output control at the time of the transition concerning the embodiment. The time chart which shows the aspect of the feedforward correction | amendment concerning the embodiment. The time chart which shows the aspect of the output control at the time of the transition concerning 2nd Embodiment. The flowchart which shows the procedure of the feedforward correction process of the output control at the time of the transition concerning the embodiment. The time chart which shows the combustion state at the time of the transition concerning the embodiment. The time chart which shows the aspect of the output control at the time of the transition concerning 3rd Embodiment. The flowchart which shows the procedure of the feedforward correction process of the output control at the time of the transition concerning the embodiment. The flowchart which shows the procedure of the feedforward correction | amendment process of the output control at the time of the transition concerning 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Gasoline engine, 14 ... Throttle valve, 20 ... Intake valve, 24 ... Spark plug, 28 ... Crankshaft, 32 ... Exhaust valve, 40 ... Valve timing variable mechanism, 90 ... ECU (One Embodiment of control apparatus of internal combustion engine) ).

Claims (13)

Target value setting means for setting a target value of an operation amount of a specific actuator among actuators for controlling an output of the internal combustion engine according to an operating state of the internal combustion engine;
Detecting means for detecting a change in demand for the operating state of the internal combustion engine;
When the change in demand is detected, at least one for controlling the output of the internal combustion engine to avoid that the combustion state of the internal combustion engine deviates from an allowable range due to a response delay of the specific actuator. A control device for an internal combustion engine, comprising: correction means for feed-forward correcting the operation amounts of two actuators.   The input used by the target value setting means for setting the target value includes a physical quantity that changes due to the operation of the actuator that is operated according to the detection result of the detection means. The control apparatus for an internal combustion engine according to claim 1. The internal combustion engine is a spark ignition internal combustion engine,
The actuator operated according to the detection result of the detection means is a flow area adjustment means for adjusting the flow area in the intake passage,
3. The control apparatus for an internal combustion engine according to claim 2, wherein the physical quantity is an intake air quantity of the internal combustion engine.   4. The control apparatus for an internal combustion engine according to claim 3, wherein the correction means includes means for reducing a change speed of the flow passage area by the flow passage area adjustment means for adjusting the flow passage area in the intake passage.   5. The internal combustion engine according to claim 4, wherein the correction means further comprises means for compensating for a delay in the change in the output torque of the internal combustion engine due to a reduction in the change speed of the flow passage area by correcting the ignition timing. Engine control device.   When the change in the request is detected, the correction means sets the target value of the operation amount of the specific actuator to a change in the request from a value set by the target value setting means in accordance with each operation state. The control device for an internal combustion engine according to any one of claims 1 to 5, further comprising a transient target value setting means for setting a value on the side assumed to change with the transition.   The transient target value setting means sets the target value of the operation amount of the specific actuator to the predicted value by predicting the value after the change of the target value accompanying the change of the request. 7. The control device for an internal combustion engine according to claim 6,   The internal combustion engine according to any one of claims 1 to 7, wherein the specific actuator is a valve characteristic variable device that varies a valve characteristic of at least one of an intake valve and an exhaust valve of the internal combustion engine. Control device. The intake valve and the exhaust valve of the internal combustion engine open and close in accordance with the rotation operation of the cam shaft that rotates in conjunction with the output shaft of the internal combustion engine,
9. The internal combustion engine according to claim 8, wherein the valve characteristic variable device comprises means for varying a relative rotational phase difference between the output shaft of the internal combustion engine and the cam shaft. Control device.   The correction means is estimated by an estimation means for estimating a combustion state of the internal combustion engine realized by setting the target value by the target value setting means when the change in the request is detected, and is estimated by the estimation means. A determination means for determining whether or not the combustion state is within an allowable range; and when it is determined that the combustion state is out of the allowable range, the operation amount of the at least one actuator is feedforward corrected so as to be within the allowable range The control device for an internal combustion engine according to any one of claims 1 to 9, further comprising: means.   11. The control device for an internal combustion engine according to claim 1, wherein the change in the request is a change in a required torque of the internal combustion engine.   The control device for an internal combustion engine according to claim 11, wherein the detection means detects the change in the required torque based on a detected value of an operation amount of an accelerator operation member.   The control device for an internal combustion engine according to any one of claims 1 to 12, wherein the change in the request is a change toward a reduction in a required torque of the internal combustion engine.

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