JP2017040241A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of variably setting an opening degree and valve characteristics of a recirculation valve in accordance with respective operation points, and capable of suppressing deterioration of torque.SOLUTION: A valve characteristic processing section M10 variably sets valve timing in accordance with an operation point of an internal combustion engine 10. An opening degree setting processing section M12 variably sets an opening degree of a recirculation valve 72 in accordance with the operation point of the internal combustion engine 10. A control section 90 fully closes the recirculation valve 72 regardless of the operation point when variable control of the valve timing by the valve characteristic processing section M10 is not permitted.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a variable valve system that changes a valve characteristic that is at least one of a valve timing, a valve lift amount, and a valve operating angle of an engine valve, and an exhaust gas recirculation passage that communicates an intake passage and an exhaust passage of an internal combustion engine. The present invention also relates to a control device for an internal combustion engine that controls an internal combustion engine that includes a recirculation valve that opens and closes the exhaust gas recirculation passage.

  As this type of control device, for example, as described in Patent Document 1, a variable valve is operated when an external EGR mechanism (recirculation valve) is operated to control an external EGR amount (exhaust recirculation amount). A device that controls the valve timing of an engine valve by an apparatus is known (paragraph “0002” or the like).

  It is well known that the control of the exhaust gas recirculation amount is executed as open loop control by determining the opening degree of the recirculation valve for each operating point determined by the rotational speed and load of the internal combustion engine. That is, when the valve characteristics such as the valve timing of the engine valve are determined for each operating point, at least in the steady state, the differential pressure between the intake passage side of the return valve and the exhaust passage side of the return valve is determined for each operating point. . On the other hand, the exhaust gas recirculation amount is determined according to the differential pressure and the opening degree of the recirculation valve. For this reason, by determining the opening degree for each operating point, the exhaust gas recirculation amount can be controlled in an open loop.

JP 2004-285860 A

  By the way, when executing the variable setting process of the valve characteristics by the variable valve operating apparatus, several conditions are usually imposed. For example, when the variable valve operating apparatus is of a hydraulic type and the hydraulic pressure is increased by the power of the internal combustion engine, the variable setting process is not permitted during the period until the hydraulic pressure increases. In addition, when the variable valve system is one that makes the valve timing variable, the variable setting process is not permitted during the period until the initial position learning process in which the valve timing is fixed when the engine is stopped is completed. is there.

  If the open-loop control of the exhaust gas recirculation amount is executed when the variable valve characteristic setting process is not performed, the torque may decrease due to the execution of the open-loop control.

  First, when the open loop control of the exhaust gas recirculation amount is executed when the variable setting process is not performed, the differential pressure between the intake passage side and the exhaust passage side of the recirculation valve in the exhaust recirculation passage This is because there is a possibility that the pressure difference greatly deviated from the precondition for setting the opening degree of the valve. When the difference in the differential pressure is such that the pressure on the exhaust passage side becomes higher than expected on the intake passage side of the recirculation valve, the exhaust gas recirculation amount flowing from the exhaust recirculation passage into the intake passage is the desired exhaust return amount. There is a possibility that the flow rate is excessively higher than the flow rate, and in that case, there is a risk of causing misfire of the internal combustion engine or engine stall. In other words, the torque may decrease.

  Secondly, since the charging efficiency when the opening degree of the reflux valve is the same according to the valve characteristic, when the variable setting process of the valve characteristic is not performed, the opening degree is set for each operating point. This is because the actual filling efficiency may deviate from the assumed filling efficiency. If this shift is a shift in which the actual charging efficiency is lower than the assumed charging efficiency, there is a concern that the amount of fresh air taken into the combustion chamber will be insufficient. In such a case, if the exhaust gas is caused to flow from the exhaust gas recirculation passage to the intake air passage by opening the recirculation valve, the exhaust gas prevents the fresh air from being sucked into the combustion chamber, and the amount of fresh air sucked into the combustion chamber. May be insufficient. And when the situation where the amount of fresh air suck | inhaled in a combustion chamber runs short occurs, there exists a possibility that a torque may fall.

  The present invention has been made in view of such circumstances, and its purpose is to variably set the opening degree and valve characteristics of the reflux valve in accordance with each of a plurality of operating points, and to reduce torque. An object of the present invention is to provide a control device for an internal combustion engine that can be suppressed.

  An internal combustion engine control device includes: a variable valve gear that changes a valve characteristic that is at least one of a valve timing, a valve lift amount, and a valve operating angle of an engine valve; and an exhaust gas that communicates an intake passage and an exhaust passage of the internal combustion engine. An internal combustion engine including a recirculation passage and a recirculation valve that opens and closes the exhaust recirculation passage is controlled, and the recirculation valve is operated according to each of a plurality of operating points determined by the rotational speed and load of the internal combustion engine. An opening degree setting processing unit that variably sets the opening degree of the reflux valve, and a valve characteristic processing unit that variably sets the valve characteristic by operating the variable valve device according to each of the plurality of operating points. In the control device for an internal combustion engine provided, when the processing for variably setting the valve characteristic according to each of the plurality of operating points is not permitted, The operating point of the engine, the opening degree by the degree of opening setting processing unit is even operating point is set to a nonzero value, to perform a reflux control stop processing of the recirculation valve is fully closed.

  In the above configuration, the opening degree of the recirculation valve is variably set according to the operating point of the internal combustion engine, and the valve characteristic is also variably set according to the operating point. In this case, when the operating point of the internal combustion engine is an operating point at which the valve characteristic is variably set by the valve characteristic processing unit, the processing for variably setting the valve characteristic is not permitted. As described above, when the opening degree of the reflux valve is variably set to a value larger than zero, the torque may be insufficient. In this regard, in the above configuration, when the processing for variably setting the valve characteristics is not permitted, the operating point of the internal combustion engine is an operating point at which the opening degree is set to a value other than zero by the opening degree setting processing unit. Also, a reflux control stop process is executed in which the reflux valve is fully closed. For this reason, even if the pressure on the exhaust passage side of the recirculation valve becomes excessively higher than the pressure on the intake passage side of the recirculation valve, the amount of exhaust flowing into the intake passage through the exhaust recirculation passage becomes zero. Even when there is a concern that the amount of fresh air sucked into the combustion chamber will be insufficient, fresh air is sucked into the combustion chamber due to the exhaust flowing into the intake passage via the exhaust recirculation passage. There is no hindrance. Therefore, in the above configuration, the opening degree of the return valve and the valve characteristic are variably set according to each of the plurality of operating points, and a reduction in torque can be suppressed.

The figure which shows the control apparatus concerning one Embodiment, and the control object of a control apparatus. The flowchart which shows the procedure of the operation process of the reflux valve which the control apparatus concerning the embodiment performs.

Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to the drawings.
As shown in FIG. 1, the intake passage 12 of the internal combustion engine 10 is provided with a throttle valve 14 having a variable cross-sectional area, and a fuel injection valve 16 is provided downstream of the throttle valve 14. ing. The air-fuel mixture of the fuel injected by the fuel injection valve 16 and the air sucked from the upstream side of the intake passage 12 is combusted by the cylinder 20 and the piston 22 as the intake valve 18 opens. Inhaled. A spark plug 26 is exposed in the combustion chamber 24. The air-fuel mixture sucked into the combustion chamber 24 is used for combustion by spark discharge by the spark plug 26. The energy generated by the combustion is converted into rotational energy of the crankshaft 28 that is the engine output shaft through the displacement of the piston 22.

The air-fuel mixture subjected to combustion in the combustion chamber 24 is discharged into the exhaust passage 32 as exhaust gas by the valve opening operation of the exhaust valve 30.
The intake valve 18 is driven to open and close as the intake camshaft 40 rotates. The intake camshaft 40 is provided with a valve timing variable mechanism 52 of a hydraulically driven valve timing variable device 50 that adjusts the opening / closing timing of the intake valve 18, that is, the valve timing without changing the lift amount and the operating angle. Yes. Then, the rotational force of the crankshaft 28 is transmitted from the timing chain 43 to the variable valve timing mechanism 52 and is transmitted to the intake camshaft 40 via the variable valve timing mechanism 52. When the rotational force of the crankshaft 28 is transmitted to the intake camshaft 40, the intake valve 18 is driven to open and close by the rotation of the cam 42 provided integrally with the intake camshaft 40.

  The variable valve timing device 50 includes an oil control valve (OCV 54) in addition to the variable valve timing mechanism 52. The OCV 54 adjusts the amount of hydraulic fluid discharged from the engine-driven oil pump 60 to be input to the variable valve timing mechanism 52 and adjusts the amount of hydraulic fluid discharged from the variable valve timing mechanism 52. It is an electronically controlled valve body.

The internal combustion engine 10 includes an exhaust recirculation passage 70 that connects the intake passage 12 and the exhaust passage 32, and a recirculation valve 72 that opens and closes the exhaust recirculation passage 70.
A crank angle sensor 80 that detects the rotational speed NE is provided near the crankshaft 28, and an accelerator sensor that detects an accelerator operation amount ACCP that is the operation amount is provided near the accelerator pedal 82. 84 is provided. The cam angle sensor 86 is provided in the vicinity of the intake camshaft 40 to detect the rotation angle of the intake camshaft 40, and the intake pressure sensor 88 is connected to the exhaust gas recirculation passage 70 in the intake passage 12. The downstream pressure is detected.

  The control device 90 controls the internal combustion engine 10 and outputs operation signals to various actuators in order to control the control amount (torque, exhaust characteristics, etc.). Specifically, the control device 90 outputs the operation signal MS1 to the OCV 54, outputs the operation signal MS2 to the recirculation valve 72, outputs the operation signal MS3 to the fuel injection valve 16, and outputs the operation signal MS4 to the spark plug 26. The operation signal MS5 is output to the throttle valve 14.

  FIG. 1 is a block diagram showing a part of the processing executed by the control device 90. The following processing by each processing unit is processing realized by a program stored in a memory in the control device 90 being executed by the CPU.

  The valve characteristic processing unit M10 outputs the operation signal MS1 to the OCV 54, thereby operating the valve timing varying device 50 to variably set the valve timing of the intake valve 18. Specifically, the valve characteristic processing unit M10 variably sets the valve timing based on a map that defines the relationship between each of the operating points determined according to the rotational speed NE and the load KL and the valve timing. Here, the map is data that defines the value of the output variable (here, valve timing) in each of a plurality of discrete values of the input variables (here, rotational speed NE and load KL). Hereinafter, the operating points corresponding to the discrete input variables stored in the map may be referred to as map points. FIG. 1 schematically shows a map that stores the valve timings aij of a plurality of map points. Here, the variable i designates the load KL. If the variable i is the same, it means that the load KL is the same. The variable j designates the rotational speed NE. If the variable j is the same, it means that the rotational speed NE is the same. Specifically, when the current operating point matches one of the map points, the valve characteristic processing unit M10 sets the valve timing aij determined by the operating point as a target value, and sets the actual valve timing as the target value. The OCV 54 is operated to control it. On the other hand, if the actual operating point does not coincide with any map point, the target value is calculated by interpolation calculation of the valve timing aij at a plurality of map points close to the actual operating point, and the actual valve timing is set as the target. The OCV 54 is operated to control the value. Specifically, for example, the valve timing is detected based on the output value of the crank angle sensor 80 and the output value of the cam angle sensor 86, and the operation signal MS1 for feedback-controlling the detected valve timing to the target value is generated. And output.

The load KL is a required torque of the internal combustion engine 10 corresponding to the accelerator operation amount ACCP.
The opening degree setting processing unit M12 operates the recirculation valve 72 by outputting the operation signal MS2 to the recirculation valve 72, and variably sets the opening degree of the recirculation valve 72 according to the operating point of the internal combustion engine 10. Specifically, the opening degree setting processing unit M12 variably sets the opening degree based on a map that defines the relationship between each of a plurality of map points determined according to the rotational speed NE and the load KL and the opening degree. FIG. 1 schematically shows a map in which the opening degrees bij of a plurality of map points are stored. Here, the variable i designates the load KL. If the variable i is the same, it means that the load KL is the same. The variable j designates the rotational speed NE. If the variable j is the same, it means that the rotational speed NE is the same. Specifically, when the current operating point matches one of the map points, the opening degree setting processing unit M12 sets the opening degree bij determined by the operating point as a target value, and sets the opening degree of the reflux valve 72 as a target. An operation signal MS2 is output to control the value. On the other hand, if the actual operating point does not match any map point, the target value is calculated by interpolation calculation of the opening degrees bij at a plurality of map points close to the actual operating point, and the opening degree of the reflux valve 72 is calculated. The operation signal MS2 is output to control the value to the target value.

  In the present embodiment, the map point where the opening degree bij is determined is the same as the map point where the valve timing aij is determined. That is, for example, the map point where the opening degree b11 is determined is the same as the map point where the valve timing a11 is determined, and the map point where the opening degree b22 is determined and the map point where the valve timing a22 is determined. Both are the same.

  The opening degree bij is an open loop operation amount for controlling the amount of exhaust gas (exhaust gas recirculation amount) flowing into the intake passage 12 via the exhaust gas recirculation passage 70 to a target value. The opening degree bij is a conforming value for making the exhaust gas recirculation amount at which the exhaust characteristic and the fuel consumption amount become appropriate values when the internal combustion engine 10 is steadily operated at the operating point specified by the variable (i, j). It is. Here, it is assumed that the valve timing of the intake valve 18 is controlled to a value set by the valve characteristic processing unit M10. In other words, the opening degree bij is an appropriate value when the valve timing of the intake valve 18 is controlled to the target value set by the valve characteristic processing unit M10.

  The abnormality diagnosis processing unit M14 diagnoses whether or not the valve timing variable device 50 is abnormal. Specifically, the abnormality diagnosis processing unit M14 diagnoses, for example, whether the cam angle sensor 86 is abnormal, whether the OCV 54 is disconnected or shorted, whether there is an abnormality in the valve timing of the intake valve 18, and the like. Here, a known diagnostic method may be used.

  The most retarded angle learning processing unit M16 learns the most retarded position of the valve timing. Specifically, the variable valve timing mechanism 52 according to the present embodiment is provided with a lock pin that fixes the valve timing of the intake valve 18 at the most retarded position, and the valve timing of the intake valve 18 is the lock pin. The most retarded angle position is learned by detecting the valve timing at the most retarded angle position. The valve timing aij is defined as an advance amount from the most retarded position serving as a reference. The valve characteristic processing unit M10 is based on the most retarded position learned by the most retarded angle learning processing unit M16. The actual valve timing is controlled to the target value defined as the advance amount from the most retarded position. Incidentally, the most retarded position according to the present embodiment is the timing at which the charging efficiency is lowest in the variable range of the valve timing when the opening degree of the throttle valve 14 and the opening degree of the reflux valve 72 are the same. ing.

  The hydraulic pressure increase determination processing unit M18 determines whether or not the hydraulic oil pressure output from the OCV 54 to the variable valve timing mechanism 52 has increased to a value that can guarantee the operation of the variable valve timing device 50. This is a process provided in view of the fact that the hydraulic pressure of the hydraulic oil output from the OCV 54 is low when the internal combustion engine 10 is started because the oil pump 60 is an engine drive type. The hydraulic pressure increase determination processing unit M18 may determine that the hydraulic pressure has increased, for example, when a predetermined time has elapsed since the start of the internal combustion engine 10.

  In the valve characteristic processing unit M10, the abnormality diagnosis processing unit M14 has not been diagnosed as having an abnormality, the most retarded angle learning processing unit M16 has completed the most retarded angle learning, and the hydraulic pressure increase determination processing unit When the logical product with the determination that the hydraulic pressure has increased by M18 is true, the above processing for variably setting the valve timing is executed.

On the other hand, the opening degree setting processing unit M12 executes the operation of the reflux valve 72 when the valve characteristic processing unit M10 variably sets the valve timing. This will be described below.
FIG. 2 shows a procedure for operating the reflux valve according to the present embodiment. This process is repeatedly executed by the control device 90, for example, at a predetermined cycle.

  In the series of processes shown in FIG. 2, the control device 90 first determines whether there is a request other than cooperative control between the opening degree of the recirculation valve 72 and the valve timing of the intake valve 18 (S10). Here, the cooperative control is the cooperation of the variable setting process of the valve timing by the valve characteristic processing unit M10 and the variable setting process of the opening degree by the opening degree setting processing unit M12, and the fuel consumption rate and the exhaust characteristic of the internal combustion engine 10. This is a process for controlling well. On the other hand, as a request other than the cooperative control, specifically, for example, there is a request for abnormality diagnosis processing of the reflux valve 72. In this abnormality diagnosis process, during the fuel cut process for stopping fuel injection, the recirculation valve 72 is forcibly opened to determine whether or not gas has flowed from the exhaust recirculation passage 70 into the intake passage 12. This is a process for determining based on the detection value of the sensor 88. Further, as a request other than the cooperative control, there is a request for processing for driving the reflux valve 72 for an inspection in a factory or the like. The process of driving here is executed by the control device 90 when, for example, a command for forcibly driving the reflux valve 72 is input to the control device 90 from the outside of the control device 90.

When determining that the request is present (S10: YES), the control device 90 forcibly operates the reflux valve 72 according to the request (S12).
On the other hand, when determining that there is no request (S10: NO), the control device 90 indicates that the abnormality diagnosis processing unit M14 has not diagnosed that there is an abnormality, and the most retarded angle learning processing unit M16 performs the most retarded angle learning. It is determined whether the logical product of the completion of the process and the determination that the hydraulic pressure has increased by the hydraulic pressure increase determination processing unit M18 is true (S14). This process is a process of determining whether or not the variable setting process of the valve timing of the intake valve 18 is permitted by the valve characteristic processing unit M10. If the controller 90 determines that the logical product is true (S14: YES), the controller 90 sets the reflux valve 72 based on the map calculation of the opening degree of the reflux valve 72 as a process by the opening degree setting processing unit M12. The process to operate is performed (S16).

  On the other hand, when determining that the logical product is false (S14: NO), the control device 90 sets the opening degree of the recirculation valve 72 to zero (S18). That is, a reflux control stop process is performed to fully close the reflux valve 72.

In addition, the control apparatus 90 once complete | finishes this series of processes, when the process of step S12, S16, S18 is completed.
Here, the operation of the present embodiment will be described.

  When a startup request for the internal combustion engine 10 is generated, the control device 90 starts the internal combustion engine 10. And the control apparatus 90 performs the process by the most retarded angle learning process part M16, and the process by the hydraulic pressure raise determination process part M18. During the period in which these processes are executed, the control device 90 performs variable setting processing of the valve timing of the intake valve 18 by the valve characteristic processing unit M10 and variable opening degree of the return valve 72 by the opening degree setting processing unit M12. Do not execute the setting process. As a result, the intake valve 18 is fixed at the most retarded position. On the other hand, the recirculation valve 72 is fully closed even when the operating point of the internal combustion engine 10 is an operating point at which the opening degree is set to a value other than zero by the opening degree setting processing unit M12.

  After that, when the processing by the most retarded angle learning processing unit M16 is completed and the hydraulic pressure increase determination processing unit M18 determines that the hydraulic pressure has increased, the abnormality diagnosis processing unit M14 does not diagnose that there is an abnormality. Under these conditions, the valve characteristic processing unit M10 executes variable setting processing of the valve timing of the intake valve 18. Then, when the variable setting process of the valve timing of the intake valve 18 by the valve characteristic processing unit M10 is executed, the variable setting process of the opening degree of the recirculation valve 72 is executed by the opening degree setting processing unit M12.

According to the present embodiment described above, the following effects can be obtained.
(1) When the variable setting process of the valve timing of the intake valve 18 by the valve characteristic processing unit M10 is not permitted, the valve timing of the intake valve 18 is fixed at the most retarded position, so Qi is less likely to be inhaled. In particular, when the required torque is large, it is difficult to compensate for the decrease in the amount of fresh air even if the opening degree of the throttle valve 14 is increased. In this case, when the recirculation valve 72 is opened, the exhaust gas flowing into the intake passage 12 from the exhaust recirculation passage 70 is sucked into the combustion chamber 24, so that a new one is introduced into the combustion chamber 24 compared to the case where the recirculation valve 72 is not opened. There is a risk that it will become more difficult to get in, and the torque may be insufficient. On the other hand, in this embodiment, when the variable setting process of the valve timing of the intake valve 18 is not permitted by the valve characteristic processing unit M10, the recirculation valve 72 is fully closed. Thereby, the fall of torque can be controlled.

<Other embodiments>
In addition, you may change at least 1 of each matter of the said embodiment as follows. In the following, items described in the column of “Means for Solving Problems” are itemized, and there is a part that illustrates the correspondence with the items in the above embodiment by reference numerals, etc. There is no intention to limit the items to the items in the embodiment illustrating the correspondence.

・ "Variable valve gear (50)"
The valve timing varying device 50 may include an intermediate lock mechanism that locks the valve timing of the intake valve 18 at a valve timing intermediate between the most retarded angle position and the most advanced angle position. In this case, if the intermediate valve timing is learned as the initial position, the valve timing is variably set to be fixed at the intermediate valve timing for the period until the learning is completed. When the opening degree of the recirculation valve 72 is variably set while being fixed at an intermediate valve timing by prohibition, the valve timing of the intake valve 18 is retarded from the intermediate valve timing unless prohibited. It is possible that the opening degree is set to a value larger than zero at the operating point that is assumed to be assumed to be. In this case, if the intermediate valve timing is a timing at which the pressure on the exhaust passage 32 side is higher than the pressure on the intake passage 12 side than the recirculation valve 72, the recirculation valve 72 is. The pressure on the exhaust passage 32 side becomes higher than expected than the pressure on the intake passage 12 side, and the exhaust gas recirculation amount may be excessive. For this reason, also in this case, the control device 90 executes the recirculation control stop process for fully closing the recirculation valve 72 when the variable setting of the valve timing is not permitted.

  In the above embodiment, the intake valve 18 includes the valve timing varying device 50 that varies the valve timing. However, the present invention is not limited to this. For example, the exhaust valve 30 may be provided with a valve timing varying device that varies the valve timing. In this case, the initial position of the valve timing may be the most advanced angle position. In this case, if learning is performed using the most advanced position as the initial position, variable setting of the valve timing is prohibited during the period until the learning is completed. If the opening degree of the recirculation valve 72 is variably set when the variable setting of the valve timing is prohibited and fixed at the most advanced position, the valve timing of the exhaust valve 30 is the most advanced if not prohibited. At an operating point that is assumed to be retarded from the angular position, the opening degree may be set to a value larger than zero. Then, when the timing on the retarded side compared to the most advanced position is a timing at which the exhaust gas is likely to blow back, if the valve timing of the exhaust valve 30 is retarded from the most retarded position, the exhaust The pressure on the intake passage 12 side increases due to the blowback. For this reason, when it is fixed to the most advanced position, the pressure on the exhaust passage 32 side becomes higher than expected than the pressure on the intake passage 12 side of the recirculation valve 72, and the exhaust gas recirculation amount may be excessive. For this reason, also in this case, the control device 90 executes the recirculation control stop process for fully closing the recirculation valve 72 when the variable setting of the valve timing is not permitted.

  Further, the valve timing is not limited to variable without changing the lift amount. For example, a lift amount variable device that makes the lift amounts of the intake valve 18 and the exhaust valve 30 variable may be used. When this includes an increase in the operating angle when the lift amount is increased, a state where the intake valve 18 is fixed at a small operating angle may be set as the initial position. In this case, if the initial position is learned, variable setting of the lift amount is prohibited during the period until the learning is completed. When the opening degree of the recirculation valve 72 is variably set when the variable setting of the lift amount is prohibited, it is assumed that the closing timing of the intake valve 18 is more retarded unless it is prohibited. At the operating point being operated, the aperture may be set to a value greater than zero. Further, the valve closing timing on the more retarded side may be set to a timing at which the charging efficiency is lowered as compared with the initial position due to the return of the intake air from the combustion chamber 24 to the intake passage 12. In this case, if the closing timing of the intake valve 18 is more advanced than expected, the charging efficiency is higher than expected, the pressure in the intake passage 12 is lower than expected, and the intake of the recirculation valve 72 is increased. The pressure on the exhaust passage 32 side becomes higher than expected than the pressure on the passage 12 side, and the exhaust gas recirculation amount may be excessive. For this reason, also in this case, the control device 90 executes a reflux control stop process for fully closing the reflux valve 72 when variable setting of the lift amount is not permitted.

  The variable valve timing device 50 is not limited to a hydraulic one, but may be, for example, a motor. This can be realized, for example, as a configuration in which the sun gear, the carrier, and the ring gear of the planetary gear mechanism are allocated and connected to the intake camshaft 40, the crankshaft 28, and the electric motor, respectively. Further, both the intake valve 18 and the exhaust valve 30 may be provided with a valve timing variable device that makes the valve timing variable. Furthermore, you may provide both a valve timing variable apparatus and a lift amount variable apparatus. Also, the intake valve 18 and the exhaust valve 30 may be electromagnetically driven valves that open and close regardless of the rotational power of the crankshaft 28. In this case, at least one of the valve timing, the valve lift amount, and the valve operating angle can be variably set by electronic control. Thus, even when various types of variable valve actuating devices are used, problems similar to those in the above-described embodiment and its modifications may occur when variable characteristic setting processing is not permitted. Therefore, the control device 90 executes a reflux control stop process for bringing the reflux valve 72 into a fully closed state.

・ “When variable setting processing is not permitted (S14: NO)”
For example, when the variable valve timing mechanism is configured with an electric motor as described in the section “Variable valve operating device”, the condition that the hydraulic pressure increase determination is made is excluded from the variable setting permission conditions. Also good.

  Also, initial value learning may be omitted. Even in this case, when the variable valve apparatus is abnormal, the valve characteristic does not become a value corresponding to the operating point. Therefore, if the opening degree of the recirculation valve 72 is controlled by the open loop, the torque may be reduced.

  Instead of determining whether or not the condition that the variable setting process for the valve characteristic is not permitted is satisfied, for example, the control device 90 sets a flag indicating that the variable is not permitted when the variable setting process for the valve characteristic is not permitted. If the flag is set, it may be determined that processing for variably setting the valve characteristics is not permitted.

・ About map points
In the above embodiment, the map points that define the opening degree bij of the recirculation valve 72 are matched with the map points that define the valve timing aij, but this is not limitative. Even if the map point that defines each of the opening degrees bij is different from the map point that defines each of the valve timings aij, there are a region in which the opening degree is variably set and a region in which the valve timing is variably set. In the case of overlapping, the control device 90 sets the opening degree and valve timing corresponding to the same operating point at any operating point in the overlapping region. In this case, the opening degree at the operating point is a value based on the valve timing at the operating point. In this case, when the valve timing is not variably set in accordance with the operating point in the overlapping region, the case where the valve timing is variably set is the difference between the intake passage 12 side of the recirculation valve 72 and the exhaust passage 32 side of the recirculation valve 72. The differential pressure is different, or the charging efficiency when the opening degree of the throttle valve 14 and the reflux valve 72 is the same is different.

・ About load
The torque is not limited to the required torque of the internal combustion engine 10 corresponding to the accelerator operation amount ACCP. For example, a target value for the amount of air to be taken into the combustion chamber 24 based on the required torque may be calculated using a model, and a value based on the calculated amount of air may be used as the load KL. However, the present invention is not limited to this. For example, an air flow meter may be provided, and the load KL may be determined based on the detected value.

・ "About the control device (90)"
The program stored in the memory is not limited to the one executed by the CPU, but may be one that executes hardware processing such as an ASIC.

  M10 ... Valve characteristic processing unit, M12 ... Opening degree setting processing unit, M14 ... Diagnosis processing unit, M16 ... Most retarded angle learning processing unit, M18 ... Hydraulic pressure increase determination processing unit, 10 ... Internal combustion engine, 12 ... Intake passage, 14 ... Throttle valve, 16 ... fuel injection valve, 18 ... intake valve, 20 ... cylinder, 22 ... piston, 24 ... combustion chamber, 26 ... ignition plug, 28 ... crankshaft, 30 ... exhaust valve, 32 ... exhaust passage, 40 ... intake Cam shaft, 42 ... Cam, 43 ... Timing chain, 50 ... Valve timing variable device, 52 ... Valve timing variable mechanism, 54 ... OCV, 60 ... Oil pump, 70 ... Exhaust recirculation passage, 72 ... Recirculation valve, 80 ... Crank angle Sensor 82 Accelerator pedal 84 Accelerator sensor 86 Cam angle sensor 88 Intake pressure sensor 90 Control device

Claims (1)

A variable valve system that changes a valve characteristic that is at least one of a valve timing, a valve lift amount, and a valve operating angle of an engine valve, an exhaust gas recirculation passage that communicates an intake passage and an exhaust passage of the internal combustion engine, and the exhaust gas recirculation An internal combustion engine including a recirculation valve that opens and closes a passage is controlled,
An opening degree setting processing unit that variably sets the opening degree of the recirculation valve by operating the recirculation valve in accordance with each of a plurality of operating points determined by the rotational speed and load of the internal combustion engine;
A control device for an internal combustion engine, comprising: a valve characteristic processing unit configured to variably set the valve characteristic by operating the variable valve device according to each of the plurality of operating points;
When the process of variably setting the valve characteristic according to each of the plurality of operating points is not permitted, the operating point of the internal combustion engine is set to a value other than zero by the opening degree setting processing unit. A control device for an internal combustion engine that executes a recirculation control stop process for fully closing the recirculation valve even at an operating point.