JP2009115102A - Controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for an internal combustion engine capable of enhancing the controlling accuracy of the ignition timing control even when the reliability of the calculated suction air amount is likely to degrade, and also capable of reducing the manufacturing costs. <P>SOLUTION: The controller 1 has an ECU 2 which calculates a calculative suction amount Gcyl (Step 17), calculates in accordance with the engine speed NE, a maximum presumptive suction amount Gcyl_max that can be sucked into a cylinder 3a at the engine speed NE (Step 50), calculates a normalized suction amount Kgcyl as the ratio of Gcyl to Gcyl_max (Step 51), and decides the ignition timing Iglog in accordance with the obtained calculations and the engine speed NE (Steps 52 and 54). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that controls the ignition timing of an internal combustion engine in which the amount of intake air taken into a cylinder by a variable intake mechanism is freely changed.

  2. Description of the Related Art Conventionally, a control device for an internal combustion engine in which an intake air amount sucked into a cylinder by a variable intake mechanism is freely changed is disclosed in Patent Document 1. This control device controls the amount of intake air via a variable intake mechanism, an air flow sensor for detecting the air flow rate in the intake passage of the internal combustion engine, a crank angle sensor for detecting the rotation state of the crankshaft, An accelerator opening sensor that detects the opening of the accelerator pedal (hereinafter referred to as “accelerator opening”) and a controller that receives detection signals from these sensors are provided. The controller calculates the engine speed based on the detection signal of the crank angle sensor and calculates the intake air amount based on the detection signal of the air flow sensor. Further, the internal combustion engine is provided with a throttle valve mechanism and a variable valve lift mechanism as a variable intake mechanism. The throttle valve mechanism freely changes the air flow rate in the intake passage, and the variable valve lift mechanism. Thus, the lift of the intake valve (hereinafter referred to as “valve lift”) is freely changed.

  In this control device, the intake air amount is controlled by the controller as described below. First, based on the engine speed, the accelerator opening, the intake air amount, and the like, it is determined what operating load range the internal combustion engine is in. When it is determined that the internal combustion engine is in the low rotation and low load range including the idle operation range, the valve lift is controlled to a predetermined low lift via the variable valve lift mechanism and the throttle valve mechanism is used. Thus, the opening degree of the throttle valve is controlled to a value corresponding to the engine speed and the accelerator opening degree. On the other hand, when it is determined that the internal combustion engine is in the medium rotation and medium load range to the high rotation and high load range, the throttle valve is controlled to the fully open state, and the valve lift corresponds to the engine speed and the accelerator opening. Controlled by value.

JP 2003-254100 A

  In the above-described conventional control device, the intake air amount may not be appropriately calculated due to the low resolution of the air flow sensor. For example, there is an internal combustion engine in which the diameter of the intake passage is set to a large value (that is, a large diameter) in order to reduce the flow resistance in the intake passage in order to increase the charging efficiency of the intake air into the cylinder. When the conventional control device is applied to such an internal combustion engine, when the internal combustion engine is in a low rotation and low load range, the intake air flow velocity becomes extremely low. Therefore, in the conventional control device, the air flow sensor Due to the low resolution, the intake air amount cannot be calculated appropriately, and the control accuracy of the intake air amount control decreases. As a result, if the amount of fuel supplied to the combustion chamber is controlled based on such an intake air amount, the control accuracy also decreases, which may lead to deterioration of fuel consumption and exhaust gas characteristics. In addition, since the internal combustion engine to which the above-described conventional control device is applied is provided with a throttle valve mechanism, the flow resistance in the intake passage increases accordingly.

  Further, in an internal combustion engine, the reliability of the intake air amount calculated based on the detection signal of the air flow sensor decreases due to the occurrence of intake pulsation or the intake flow velocity becoming too high in a high load range. In some cases, the above-described problem occurs.

  On the other hand, in the ignition timing control of the internal combustion engine, the engine speed and the intake air amount are used as load parameters representing the load of the internal combustion engine, and an ignition timing map value is preset for such load parameters. A technique using a timing map has been conventionally used, and it is assumed that the ignition timing is controlled by such a control technique even in the above-described large-diameter internal combustion engine. However, as described above, in the conventional control device, the intake air amount cannot be calculated appropriately due to the low resolution of the air flow sensor in the low load region, so the control accuracy of the ignition timing control is also reduced. End up. In addition, because the intake charging efficiency in the cylinder changes according to the engine speed, the maximum value of the intake air amount in a high load range where knocking starts to occur also changes according to the engine speed. Therefore, in such a high load range, it is necessary to set the intake air amount and the maximum value finely while making them different from each other for each set engine speed. As a result, an increase in the number of data in the ignition timing map increases the number of measurements for data sampling and increases the capacity of a storage medium such as a ROM, resulting in an increase in manufacturing cost. In addition, as described above, even in an internal combustion engine in which the reliability of the intake air amount calculated based on the detection signal of the air flow sensor is reduced in a high load region, the control accuracy of the ignition timing control is reduced. End up.

  The present invention has been made to solve the above-described problems, and can improve the control accuracy of the ignition timing control even when there is a possibility that the reliability of the calculated intake air amount may be reduced. An object of the present invention is to provide a control device for an internal combustion engine that can reduce the cost.

  In order to achieve the above object, the control device 1 for the internal combustion engine 3 according to claim 1 calculates the intake air amount calculation means for calculating the intake air amount (calculated intake amount Gcyl) to be taken into the cylinder 3a of the internal combustion engine 3. (ECU 2, steps 17 and 19), engine speed detecting means (ECU 2, crank angle sensor 20) for detecting the engine speed NE of the internal combustion engine 3, and cylinders at the engine speed NE according to the engine speed NE. Maximum intake air amount calculation means (ECU 2, maximum estimated intake amount calculation unit 121, step 50) for calculating a maximum intake air amount (maximum estimated intake amount Gcyl_max) that can be inhaled into 3a, intake air amount and maximum intake air amount Timing determining means (ECU2, ignition time) for determining the ignition timing Iglog of the internal combustion engine in accordance with the ratio of one of the two to the other (normalized intake air amount Kgcyl) and the engine speed NE Controller 120, and step 52 and 54), characterized in that it comprises a.

  According to this control device for an internal combustion engine, the ignition timing of the internal combustion engine is determined in accordance with the ratio between the intake air amount and the maximum intake air amount and the engine speed, so that it is set with respect to the ratio and the engine speed. The ignition timing can be determined using the ignition timing map. When determining the ignition timing in this way, the ratio of one of the intake air amount and the maximum intake air amount to the other is a value within the range from the value 0 to the value 1, or a value within the range from the value 1 to infinity. In a high load range where the intake air amount is close to the maximum intake air amount and knocking occurs, the ratio becomes a value in the vicinity of the value 1 including the value 1, and the engine speed is different from each other. With respect to the set value, there is no variation for each set value. As a result, when the ignition timing map data is set according to the engine speed and ratio, the set data number can be set to the same number with respect to the ratio among the set values of the engine speed. Therefore, compared with the conventional case where the ignition timing map data is set for the engine speed and the intake air amount, the total number of data can be reduced, and the storage capacity of the storage medium such as ROM is reduced accordingly. Manufacturing cost can be reduced.

  According to a second aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the first aspect, the internal combustion engine 3 includes a variable intake mechanism (variable valve lift mechanism 50, variable cam phase mechanism) that freely changes the intake air amount. 70, a variable compression ratio mechanism 80), and operating state parameter detecting means (ECU2, crank angle) for detecting operating state parameters (valve lift Liftin, cam phase Cain, compression ratio Cr) representing the operating state of the variable intake mechanism. Sensor 20, rotation angle sensor 25, cam angle sensor 26, control angle sensor 27), air flow rate detecting means (air flow sensor 22) for detecting the flow rate Gin of air flowing in the intake passage 12a of the internal combustion engine 3, and the internal combustion engine Negative to detect load parameters (engine speed NE, valve lift Liftin, cam phase Cain, compression ratio Cr) representing the load of the engine 3 Parameter detecting means (ECU 2, crank angle sensor 20, rotation angle sensor 25, cam angle sensor 26, control angle sensor 27), and the intake air amount calculating means determines the intake air amount and the load parameter is predetermined. When it is in the first range (Gin_vt ≦ Gin1), it is calculated according to the operating state parameter, and when the load parameter is in a predetermined second range (Gin2 ≦ Gin_vt) different from the predetermined first range, the air flow rate Gin (Step 17).

  According to the control device for an internal combustion engine, when the load parameter is within the predetermined first range, the intake air amount is calculated according to the operation state parameter representing the operation state of the variable intake mechanism, and the load parameter is set to the predetermined value. Is calculated in accordance with the flow rate of the air flowing through the intake passage of the internal combustion engine, and the ignition timing is determined in accordance with the amount of intake air thus calculated. It is determined. Therefore, in the predetermined first range, the reliability of the detected value of the operating state parameter exceeds the reliability of the detected value of the air flow rate, so that the reliability of the intake air amount calculated according to the operating state parameter is increased. However, by setting a load range that exceeds the reliability of the intake air amount calculated according to the air flow rate, the ignition timing should be determined appropriately according to the intake air amount even in such a load region. Can do. For example, as described above, in the case of an internal combustion engine in which the intake passage is set to a large diameter, the predetermined first range may be set to a low load region, while the flow rate of air in the high load region may be set. In the case of an internal combustion engine in which the reliability of the detected value is lower than the reliability of the detected value of the operating state parameter, the predetermined first range may be set to such a high load range.

  Further, when the load parameter is in a predetermined second range that is different from the predetermined first range, the intake air amount is calculated according to the air flow rate. Therefore, the predetermined second range is used as the reliability of the air flow rate. Exceeds the reliability of the operating state parameter, so that the reliability of the intake air amount calculated according to the air flow rate exceeds the reliability of the intake air amount calculated according to the operating state parameter. In such a load range, the ignition timing can be appropriately determined according to the intake air amount. As described above, in the load range where the reliability of the intake air amount calculated according to the air flow rate exceeds the reliability of the intake air amount calculated according to the operation state parameter, and vice versa, Since the ignition timing can be appropriately determined, the control accuracy of the ignition timing control can be improved. As a result, fuel consumption and combustion stability can be improved (in this specification, “operation state parameter detection”, “load parameter detection” and “air flow rate detection” The parameters and the air flow rate are not limited to being directly detected by the sensor, but also include calculation or estimation).

  According to a third aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the second aspect, the predetermined first range and the predetermined second range are set so as not to overlap each other, and the intake air amount calculating means When the load parameter is between the predetermined first range and the predetermined second range (Gin1 <Gin_vt <Gin2), the intake air amount is calculated according to the operation state parameter and the air flow rate (step 17). It is characterized by.

  According to the control device for the internal combustion engine, when the load parameter is between the predetermined first range and the predetermined second range, the intake air amount is calculated according to the operation state parameter and the air flow rate. Unlike the case where the intake air amount used to determine the timing is switched directly from one of the value calculated according to the air flow rate and the value calculated according to the operating state parameter to the other, It is possible to avoid the occurrence of a torque step due to this, and to improve drivability.

  According to a fourth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the second or third aspect, the first failure determination means (ECU2, step 14, 92-94), and the intake air amount calculation means determines that the load is detected when the first failure determination means determines that the air flow rate detection means has failed (when the determination result of step 14 is YES). Regardless of the parameter value, the intake air amount (calculated intake air amount Gcyl) is calculated according to the operating state parameter (steps 16 and 17).

  According to this control device for an internal combustion engine, when it is determined that the air flow rate detecting means has failed, the intake air amount is calculated according to the operating state parameter regardless of the value of the load parameter. Even when the reliability of the detected value of the air flow rate is reduced due to the failure of the detection means, the ignition timing can be calculated appropriately, and good control accuracy in the ignition timing control can be ensured.

  According to a fifth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to any one of the second to fourth aspects, second failure determination means (ECU2, step for determining whether or not the variable intake mechanism has failed) 30, 60, 80 to 91) and when the second failure determination means determines that the variable intake mechanism has failed (when the determination result of step 60 is YES), the intake air amount is a predetermined value ( When it is determined by the second failure determination means that the variable intake mechanism is in failure (step 30) and the drive means (ECU2, step 76) for driving the variable intake mechanism so that the predetermined failure time value Gcyl_fs) is reached (step 30). When the result of the determination is YES), it further comprises failure target revolution speed setting means (ECU2, step 38) for setting a target revolution speed NE_fs at failure that is a target of the engine revolution speed. When it is determined by the second failure determination means that the variable intake mechanism has failed (when the determination result of step 30 is YES), the timing determination means sets the engine speed NE to the target rotation speed NE_fs at the time of failure. Thus, the ignition timing Iglog is determined by a predetermined feedback control algorithm [Equations (13) to (15)] (steps 38 and 39).

  According to this control device for an internal combustion engine, when it is determined that the variable intake mechanism has failed, the variable intake mechanism is driven so that the intake air amount becomes a predetermined value, and the engine speed is the target at the time of failure. Since the ignition timing is determined by a predetermined feedback control algorithm so as to achieve the engine speed, acceleration associated with an increase in the engine speed can be avoided by setting the predetermined value and the target engine speed at the time of failure to appropriate values. At the same time, the operation can be continued while avoiding the deceleration accompanying the decrease in the engine speed. As a result, when the internal combustion engine is used as a power source for the vehicle, it is possible to ensure the minimum necessary traveling performance in the vehicle.

  According to a sixth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to any one of the second to fifth aspects, the variable intake mechanism changes a phase Cain of the intake camshaft 5 of the internal combustion engine 3 with respect to the crankshaft 3d. A variable cam phase mechanism 70 that changes the lift Liftin of the intake valve 4 of the internal combustion engine 3, and a variable compression ratio mechanism 80 that changes the compression ratio Cr of the internal combustion engine 3. Features.

  According to the control device for an internal combustion engine, the variable intake mechanism changes the phase of the intake camshaft of the internal combustion engine with respect to the crankshaft, the variable valve lift mechanism that changes the lift of the intake valve of the internal combustion engine, and Since at least one of the variable compression ratio mechanisms for changing the compression ratio of the internal combustion engine is included, the throttle valve mechanism can be omitted, and accordingly, the flow resistance in the intake passage is reduced and the charging efficiency is increased. And manufacturing cost can be reduced.

1 is a schematic diagram showing a schematic configuration of an internal combustion engine to which a control device according to an embodiment of the present invention is applied. It is a block diagram which shows schematic structure of a control apparatus. It is sectional drawing which shows schematic structure of the variable type intake valve mechanism and exhaust valve mechanism of an internal combustion engine. It is sectional drawing which shows schematic structure of the variable valve lift mechanism of a variable intake valve mechanism. (A) It is a figure which shows the state which has the short arm of a lift actuator in the maximum lift position, and (b) the state in the minimum lift position. (A) It is a figure which shows the valve opening state of the intake valve when the lower link of the variable valve lift mechanism is at the maximum lift position, and (b) the valve opening state of the intake valve when it is at the minimum lift position. It is a figure which respectively shows the valve lift curve (solid line) of the intake valve when the lower link of the variable valve lift mechanism is at the maximum lift position, and the valve lift curve (two-dot chain line) when at the minimum lift position. It is a figure which shows typically schematic structure of a variable cam phase mechanism. By the variable cam phase mechanism, the valve lift curve (solid line) of the intake valve 4 when the cam phase is set to the most retarded value and the intake valve 4 when the cam phase is set to the most advanced value. It is a figure which shows a valve lift curve (two-dot chain line), respectively. (A) The figure which shows typically the whole structure of the variable compression ratio mechanism when the compression ratio is set to the low compression ratio, (b) The variable compression ratio when the compression ratio is set to the high compression ratio It is a figure which shows the structure of the control shaft and compression ratio actuator vicinity in a mechanism. It is a block diagram which shows schematic structure of a fuel-injection controller. It is a figure which shows an example of the map used for calculation of the basic estimated intake air amount Gcyl_vt_base. It is a figure which shows an example of the map used for calculation of the correction coefficient K_gcyl_vt. It is a figure which shows an example of the table used for calculation of the compression ratio correction coefficient K_gcyl_cr. It is a figure which shows an example of the table used for calculation of the transfer coefficient Kg. It is a block diagram which shows schematic structure of an ignition timing controller. It is a figure which shows an example of the table used for calculation of the largest estimated intake air amount Gcyl_max. It is a figure which shows an example of the map used for calculation of the correction coefficient K_gcyl_max. It is a figure which shows an example of the basic ignition timing map for Cr = Crmin & Cain = Cainrt. It is a figure which shows an example of the basic ignition timing map for Cr = Crmin & Cain = Cainad. It is a figure which shows the comparative example of the basic ignition timing map set by using the calculated intake air amount Gcyl and the engine speed NE as parameters. It is a flowchart which shows a fuel-injection control process. It is a flowchart which shows the calculation process of basic fuel injection amount Tcyl_bs. It is a flowchart which shows an ignition timing control process. It is a flowchart which shows a normal ignition timing control process. It is a flowchart which shows a variable mechanism control process. It is a figure which shows an example of the table used for calculation of target valve lift Liftin_cmd during engine starting. It is a figure which shows an example of the table used for calculation of the target cam phase Cain_cmd during engine starting. It is a figure which shows an example of the map used for calculation of target valve lift Liftin_cmd during catalyst warm-up control. It is a figure which shows an example of the map used for calculation of the target cam phase Cain_cmd during catalyst warm-up control. It is a figure which shows an example of the map used for calculation of target valve lift Liftin_cmd during normal driving | operation. It is a figure which shows an example of the map used for calculation of the target cam phase Cain_cmd during normal driving | operation. It is a figure which shows an example of the map used for calculation of target compression ratio Cr_cmd during normal driving | operation. It is a flowchart which shows the failure determination process of a variable valve lift mechanism, a variable cam phase mechanism, a variable compression ratio mechanism, and an airflow sensor.

  Hereinafter, an internal combustion engine control apparatus according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, the control device 1 includes an ECU 2. As will be described later, the ECU 2 performs fuel injection control and ignition according to the operating state of an internal combustion engine (hereinafter referred to as "engine") 3. Control processing such as timing control is executed.

  As shown in FIGS. 1 and 3, the engine 3 is an in-line multi-cylinder gasoline engine having a large number of cylinders 3a and pistons 3b (only one set is shown), and is mounted on a vehicle with an automatic transmission (not shown). Yes. The engine 3 is provided for each cylinder 3a, and opens and closes an intake valve 4 and an exhaust valve 7 that open and close an intake port and an exhaust port, an intake camshaft 5 and an intake cam 6 for driving the intake valve 4, and an intake valve 4, respectively. A variable intake valve mechanism 40 for driving, an exhaust camshaft 8 and an exhaust cam 9 for driving the exhaust valve 7, an exhaust valve mechanism 30 for opening and closing the exhaust valve 7, and a variable compression ratio mechanism for changing the compression ratio 80, a fuel injection valve 10, a spark plug 11 (see FIG. 2), and the like. In the following description, the engine 3 is assumed to be an inline 4-cylinder engine.

  The intake valve 4 has a stem 4a slidably fitted to a guide 4b, and the guide 4b is fixed to the cylinder head 3c. Further, as shown in FIG. 4, the intake valve 4 is provided with upper and lower spring seats 4c, 4d and a valve spring 4e provided therebetween, and is attached in the valve closing direction by the valve spring 4e. It is energized.

  Further, each of the intake camshaft 5 and the exhaust camshaft 8 is rotatably attached to the cylinder head 3c via a holder (not shown). An intake sprocket (not shown) is coaxially disposed on one end of the intake camshaft 5 and is rotatably provided. The intake sprocket is connected to the crankshaft 3d via a timing belt (not shown), and is connected to the intake camshaft 5 via a variable cam phase mechanism 70 described later. With the above configuration, the intake camshaft 5 rotates once every time the crankshaft 3d rotates twice. Further, the intake cam 6 is provided for each cylinder 3a on the intake camshaft 5 so as to rotate integrally therewith.

  Further, the variable intake valve mechanism 40 drives the intake valve 4 of each cylinder 3a to open and close as the intake camshaft 5 rotates, and changes the lift and valve timing of the intake valve 4 steplessly. Details thereof will be described later. In the present embodiment, “the lift of the intake valve 4 (hereinafter referred to as“ valve lift ”)” represents the maximum lift of the intake valve 4.

  On the other hand, the exhaust valve 7 has a stem 7a slidably fitted to a guide 7b, and the guide 7b is fixed to the cylinder head 3c. Further, the exhaust valve 7 includes upper and lower spring seats 7c and 7d and a valve spring 7e provided therebetween, and is urged in the valve closing direction by the valve spring 7e.

  The exhaust camshaft 8 includes an exhaust sprocket (not shown) integrated with the exhaust camshaft 8 and is connected to the crankshaft 3d via the exhaust sprocket and a timing belt (not shown). One rotation for every rotation. Further, the exhaust cam 9 is provided for each cylinder 3a on the exhaust camshaft 8 so as to rotate integrally therewith.

  Further, the exhaust valve mechanism 30 includes a rocker arm 31. The rocker arm 31 rotates with the rotation of the exhaust cam 9, thereby opening and closing the exhaust valve 7 against the urging force of the valve spring 7e. To drive.

  On the other hand, the fuel injection valve 10 is provided for each cylinder 3a, and is attached to the cylinder head 3c in an inclined state so as to inject fuel directly into the combustion chamber. That is, the engine 3 is configured as a direct injection engine. Further, the fuel injection valve 10 is electrically connected to the ECU 2, and the valve opening time and the valve opening timing are controlled by the ECU 2 as will be described later, whereby fuel injection control is executed.

  A spark plug 11 is also provided for each cylinder 3a and attached to the cylinder head 3c. The spark plug 11 is electrically connected to the ECU 2, and the discharge state is controlled by the ECU 2 so that the air-fuel mixture in the combustion chamber is combusted at a timing corresponding to an ignition timing described later.

  On the other hand, the engine 3 is provided with a crank angle sensor 20 and a water temperature sensor 21. The crank angle sensor 20 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3d rotates. The CRK signal is output at one pulse every predetermined crank angle (for example, 10 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly before the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle. In the present embodiment, the crank angle sensor 20 corresponds to load parameter detection means and engine speed detection means, and the engine speed NE corresponds to load parameters.

  Moreover, the water temperature sensor 21 is comprised, for example with the thermistor etc., and outputs the detection signal showing engine water temperature TW to ECU2. This engine water temperature TW is the temperature of the cooling water circulating in the cylinder block 3 h of the engine 3.

  Further, in the intake pipe 12 of the engine 3, the throttle valve mechanism is omitted and the intake passage 12a is formed with a large diameter, so that the flow resistance is set to be smaller than that of a normal engine. ing. The intake pipe 12 is provided with an air flow sensor 22 and an intake air temperature sensor 23 (see FIG. 2).

  The air flow sensor 22 (air flow rate detecting means) is configured by a hot-wire air flow meter, and outputs a detection signal representing the flow rate (hereinafter referred to as “air flow rate”) Gin of the air flowing through the intake passage 12a to the ECU 2. The unit of the air flow rate Gin is g / sec. Further, the intake air temperature sensor 23 outputs a detection signal representing the temperature TA (hereinafter referred to as “intake air temperature”) TA flowing through the intake passage 12a to the ECU 2.

  Further, the exhaust pipe 13 of the engine 3 is provided with a LAF sensor 24 upstream of a catalyst device (not shown). The LAF sensor 24 is composed of zirconia and a platinum electrode, etc., and linearly detects the oxygen concentration in the exhaust gas in a wide range of air-fuel ratios from a rich region richer than the stoichiometric air-fuel ratio to an extremely lean region. Is output to the ECU 2. The ECU 2 calculates a detected air-fuel ratio KACT representing the air-fuel ratio in the exhaust gas based on the value of the detection signal of the LAF sensor 24. The detected air-fuel ratio KACT is specifically calculated as an equivalence ratio.

  Next, the variable intake valve mechanism 40 described above will be described. As shown in FIG. 4, the variable intake valve mechanism 40 includes an intake camshaft 5, an intake cam 6, a variable valve lift mechanism 50, a variable cam phase mechanism 70, and the like.

  The variable valve lift mechanism 50 (variable intake mechanism) drives the intake valve 4 to open and close as the intake camshaft 5 rotates, and the valve lift Liftin is stepless between a predetermined maximum value Liftinmax and minimum value Liftinmin. And a four-bar linkage type rocker arm mechanism 51 provided for each cylinder 3a, and a lift actuator 60 (see FIG. 5) for simultaneously driving these rocker arm mechanisms 51.

  Each rocker arm mechanism 51 includes a rocker arm 52 and upper and lower links 53 and 54. One end portion of the upper link 53 is rotatably attached to the upper end portion of the rocker arm 52 via the upper pin 55, and the other end portion is rotatably attached to the rocker arm shaft 56. The rocker arm shaft 56 is attached to the cylinder head 3c via a holder (not shown).

  A roller 57 is rotatably provided on the upper pin 55 of the rocker arm 52. The roller 57 is in contact with the cam surface of the intake cam 6 and rolls on the intake cam 6 while being guided by the cam surface when the intake cam 6 rotates. As a result, the rocker arm 52 is driven in the vertical direction, and the upper link 53 rotates about the rocker arm shaft 56.

  Further, an adjustment bolt 52a is attached to the end of the rocker arm 52 on the intake valve 4 side. When the rocker arm 52 moves up and down with the rotation of the intake cam 6, the adjust bolt 52a drives the stem 4a up and down to open and close the intake valve 4 against the urging force of the valve spring 4e.

  Further, one end portion of the lower link 54 is rotatably attached to the lower end portion of the rocker arm 52 via the lower pin 58, and the connecting shaft 59 is rotatable to the other end portion of the lower link 54. It is attached. The lower link 54 is connected to a short arm 65 (to be described later) of the lift actuator 60 via the connecting shaft 59.

  On the other hand, the lift actuator 60 includes a motor 61, a nut 62, a link 63, a long arm 64, a short arm 65, and the like, as shown in FIG. The motor 61 is connected to the ECU 2 and is disposed outside the head cover 3 g of the engine 3. The rotation shaft of the motor 61 is a screw shaft 61a on which a male screw is formed, and a nut 62 is screwed onto the screw shaft 61a. The nut 62 is connected to the long arm 64 via the link 63. One end of the link 63 is rotatably attached to the nut 62 via a pin 63a, and the other end is rotatably attached to one end of the long arm 64 via a pin 63b. .

  The other end of the long arm 64 is attached to one end of the short arm 65 via a rotation shaft 66. The rotation shaft 66 is formed in a circular cross section, penetrates the head cover 3g of the engine 3, and is rotatably supported by the rotation shaft 66. As the rotation shaft 66 rotates, the long arm 64 and the short arm 65 rotate integrally therewith.

  Further, the above-described connecting shaft 59 is rotatably attached to the other end of the short arm 65, whereby the short arm 65 is connected to the lower link 54 via the connecting shaft 59. .

  Next, the operation of the variable valve lift mechanism 50 configured as described above will be described. In the variable valve lift mechanism 50, when a later-described lift control input U_Liftin from the ECU 2 is input to the lift actuator 60, the screw shaft 61a rotates, and the long arm 64 and the short arm 65 are moved by the movement of the nut 62 associated therewith. While rotating about the rotation shaft 66, the lower link 54 of the rocker arm mechanism 51 rotates about the lower pin 58 as the short arm 65 rotates. That is, the lower link 54 is driven by the lift actuator 60.

  At that time, under the control of the ECU 2, the rotation range of the short arm 65 is regulated between the maximum lift position shown in FIG. 5A and the minimum lift position shown in FIG. The rotation range 54 is also regulated between the maximum lift position indicated by a solid line in FIG. 4 and the minimum lift position indicated by a two-dot chain line in FIG.

  When the lower link 54 is at the maximum lift position, in the four-bar link constituted by the rocker arm shaft 56, the upper and lower pins 55, 58 and the connecting shaft 59, the distance between the centers of the upper pin 55 and the lower pin 58 is the rocker arm shaft. 56 and the distance between the centers of the connecting shafts 59, so that, as shown in FIG. 6A, when the intake cam 6 rotates, the contact point between this and the roller 57 is reduced. The moving amount of the adjusting bolt 52a is larger than the moving amount.

  On the other hand, when the lower link 54 is at the minimum lift position, the distance between the centers of the upper pin 55 and the lower pin 58 is shorter than the distance between the centers of the rocker arm shaft 56 and the connecting shaft 59 in the four-bar link. Accordingly, as shown in FIG. 6B, when the intake cam 6 rotates, the moving amount of the adjusting bolt 52a is smaller than the moving amount of the contact point between the intake cam 6 and the roller 57. Become.

  For the above reasons, the intake valve 4 opens with a larger valve lift Liftin when the lower link 54 is at the maximum lift position than when it is at the minimum lift position. Specifically, during the rotation of the intake cam 6, when the lower link 54 is at the maximum lift position, the intake valve 4 is opened according to the valve lift curve shown by the solid line in FIG. 7, and the valve lift Liftin has its maximum value. Liftinmax is shown. On the other hand, when the lower link 54 is at the minimum lift position, the valve is opened according to the valve lift curve shown by the two-dot chain line in FIG. 7, and the valve lift Liftin indicates the minimum value Liftinmin.

  Accordingly, in the variable valve lift mechanism 50, the valve lift Liftin is set to the maximum value Liftinmax and the minimum value Liftinmin by rotating the lower link 54 between the maximum lift position and the minimum lift position via the actuator 60. Can be changed steplessly between.

  The variable valve lift mechanism 50 is provided with a lock mechanism (not shown), and when the lift control input U_Liftin is set to a failure value U_Liftin_fs, which will be described later, or due to a disconnection or the like, the ECU 2 When the lift control input U_Liftin is not input to the lift actuator 60, the operation of the variable valve lift mechanism 50 is locked. That is, the change of the valve lift Liftin by the variable valve lift mechanism 50 is prohibited, and the valve lift Liftin is held at the minimum value Liftinmin. The minimum value Liftinmin secures a predetermined failure value Gcyl_fs described later as the intake air amount when the cam phase Cain is maintained at a lock value described later and the compression ratio Cr is maintained at the minimum value Crmin. It is set to a value that allows it. The predetermined failure time value Gcyl_fs (predetermined value) is set to a value such that the idling operation and the engine starting can be appropriately performed while the vehicle is stopped and the low-speed traveling state can be maintained during the traveling.

  The engine 3 is provided with a rotation angle sensor 25 (see FIG. 2). The rotation angle sensor 25 detects the rotation angle of the rotation shaft 66, that is, the short arm 65, and detects the rotation angle. A signal is output to the ECU 2. The ECU 2 calculates the valve lift Liftin based on the detection signal of the rotation angle sensor 25. In the present embodiment, the rotation angle sensor 25 corresponds to an operation state parameter detection unit and a load parameter detection unit, and the valve lift Liftin corresponds to an operation state parameter and a load parameter.

  Next, the aforementioned variable cam phase mechanism 70 (variable intake mechanism) will be described. This variable cam phase mechanism 70 changes the relative phase (hereinafter referred to as “cam phase”) Cain of the intake camshaft 5 with respect to the crankshaft 3d to the advance side or the retard side steplessly. It is provided at the end of the shaft 5 on the intake sprocket side. As shown in FIG. 8, the variable cam phase mechanism 70 includes a housing 71, a three-blade vane 72, a hydraulic pump 73, an electromagnetic valve mechanism 74, and the like.

  The housing 71 is formed integrally with an intake sprocket on the intake camshaft 5 and includes three partition walls 71a formed at equal intervals. The vane 72 is coaxially attached to the end of the intake camshaft 5 on the intake sprocket side, extends radially outward from the intake camshaft 5, and is rotatably accommodated in the housing 71. In the housing 71, three advance chambers 75 and three retard chambers 76 are formed between the partition wall 71 a and the vane 72.

  The hydraulic pump 73 is a mechanical type connected to the crankshaft 3d. When the crankshaft 3d rotates, along with this, the lubricating oil stored in the oil pan 3e of the engine 3 passes through the oil passage 77c. And is supplied to the electromagnetic valve mechanism 74 via the oil passage 77c in a state where the pressure is increased.

  The electromagnetic valve mechanism 74 is a combination of a spool valve mechanism 74a and a solenoid 74b, and is connected to the advance chamber 75 and the retard chamber 76 via an advance oil passage 77a and a retard oil passage 77b, respectively. At the same time, the hydraulic pressure supplied from the hydraulic pump 73 is output to the advance chamber 75 and the retard chamber 76 as the advance hydraulic pressure Pad and the retard hydraulic pressure Prt, respectively. The solenoid 74b of the electromagnetic valve mechanism 74 is electrically connected to the ECU 2, and when a later-described phase control input U_Cain is input from the ECU 2, the spool valve body of the spool valve mechanism 74a is made to respond to the phase control input U_Cain. Thus, both the advance hydraulic pressure Pad and the retard hydraulic pressure Prt are changed by moving within a predetermined movement range.

  In the variable cam phase mechanism 70 described above, during the operation of the hydraulic pump 73, the electromagnetic valve mechanism 74 operates in accordance with the control input U_Cain, whereby the advance hydraulic pressure Pad becomes the advance chamber 75 and the retard hydraulic pressure Prt becomes the retard angle. Each is supplied to the chamber 76, whereby the relative phase between the vane 72 and the housing 71 is changed to the advance side or the retard side. As a result, the aforementioned cam phase Cain is continuously between the most retarded angle value Cainrt (for example, a value corresponding to a cam angle of 0 °) and the most advanced angle value Cainad (for example, a value corresponding to a cam angle of 55 °). Thus, the valve timing of the intake valve 4 is changed steplessly between the most retarded timing shown by the solid line in FIG. 9 and the most advanced timing shown by the two-dot chain line in FIG.

  The variable cam phase mechanism 70 is provided with a lock mechanism (not shown). When the hydraulic pressure supplied from the hydraulic pump 73 is low by this lock mechanism, the phase control input U_Cain becomes a failure time value U_Cain_fs described later. When set, and when the phase control input U_Cain is not input to the electromagnetic valve mechanism 74 due to disconnection or the like, the operation of the variable cam phase mechanism 70 is locked. That is, the change of the cam phase Cain by the variable cam phase mechanism 70 is prohibited, and the cam phase Cain is held at a predetermined lock value. As described above, the predetermined lock value is the predetermined failure value Gcyl_fs as the intake air amount when the valve lift Liftin is held at the minimum value Liftinmin and the compression ratio Cr is held at the minimum value Crmin. Is set to a value that can be secured.

  As described above, in the variable intake valve mechanism 40 of the present embodiment, the variable valve lift mechanism 50 changes the valve lift Liftin continuously, and the variable cam phase mechanism 70 causes the cam phase Cain, that is, the intake valve. The valve timing 4 is changed steplessly between the most retarded timing and the most advanced timing described above. Further, as will be described later, the ECU 2 controls the valve lift Liftin and the cam phase Cain via the variable valve lift mechanism 50 and the variable cam phase mechanism 70, respectively.

  On the other hand, a cam angle sensor 26 (see FIG. 2) is provided at the end of the intake camshaft 5 opposite to the variable cam phase mechanism 70. The cam angle sensor 26 is composed of, for example, a magnet rotor and an MRE pickup, and outputs a CAM signal, which is a pulse signal, to the ECU 2 every predetermined cam angle (for example, 1 °) as the intake camshaft 5 rotates. . The ECU 2 calculates the cam phase Cain based on this CAM signal and the above-described CRK signal. In the present embodiment, the cam angle sensor 26 corresponds to an operation state parameter detection unit and a load parameter detection unit, and the cam phase Cain corresponds to an operation state parameter and a load parameter.

  Next, the aforementioned variable compression ratio mechanism 80 (variable intake mechanism) will be described with reference to FIG. This variable compression ratio mechanism 80 changes the compression ratio Cr steplessly between a predetermined maximum value Crmax and a minimum value Crmin by changing the top dead center position of the piston 3b, that is, the stroke of the piston 3b. A composite link mechanism 81 connected between the piston 3b and the crankshaft 3d, a control shaft 85 for controlling the movement of the composite link mechanism 81, a compression ratio actuator 87 for driving the control shaft 85, and the like. It is configured.

  The composite link mechanism 81 includes an upper link 82, a lower link 83, a control link 84, and the like. The upper link 82 corresponds to a so-called connecting rod, and its upper end is rotatably connected to the piston 3b via the piston pin 3f, and its lower end is connected to one end of the lower link 83 via the pin 83a. It is pivotally connected.

  The lower link 83 has a triangular shape, and two ends other than the end connected to the upper link 82 are connected to the crankshaft 3d via the crankpin 83b and the control link 84 via the control pin 83c. One end is pivotally connected. With the above configuration, the reciprocating motion of the piston 3b is transmitted to the crankshaft 3d via the composite link mechanism 81 and converted into the rotational motion of the crankshaft 3d.

  Similarly to the crankshaft 3d, the control shaft 85 extends in the depth direction in the figure, and a rotation shaft portion 85a that is rotatably supported by the cylinder block, an eccentric shaft portion 85b integrated therewith, and An arm 86 is provided. A lower end portion of the control link 84 is rotatably connected to the eccentric shaft portion 85b. The distal end portion of the arm 86 is a fork portion 86a, and the distal end portion of the drive shaft 87b of the compression ratio actuator 87 is rotatably connected to the fork portion 86a.

  The compression ratio actuator 87 is a combination of a motor and a speed reduction mechanism (both not shown), and includes a casing 87a incorporating these, a drive shaft 87b that can move in the direction of protruding from the casing 87a, and the like. Yes. In the compression ratio actuator 87, when the motor is driven in the forward / reverse rotation direction by a compression ratio control input U_Cr (described later) from the ECU 2, the drive shaft 87b is at the low compression ratio position that protrudes most from the casing 87a (FIG. 10 ( the position shown in a) and a high compression ratio position (the position shown in FIG. 10B) that is most retracted to the casing 87a side.

  With the above-described configuration, in the variable compression ratio mechanism 80, when the drive shaft 87b of the actuator 87 moves from the low compression ratio position to the high compression ratio position, the control shaft 85 is moved via the arm 86 to the rotation shaft portion 85a. Is driven to rotate counterclockwise in the figure, and accordingly, the eccentric shaft portion 85b moves downward. Accordingly, as the entire control link 84 is pushed down, the lower link 83 rotates about the crank pin 83b in the clockwise direction in the drawing, and the upper link 82 rotates counterclockwise in the drawing about the piston pin 3f. Rotate around. As a result, the piston pin 3f, the upper pin 83a, and the crank pin 83b come closer to a straight line than at the low compression ratio position, so that the piston pin 3f and the crank pin 83b when the piston 3b reaches the top dead center The compression distance Cr increases as the connecting linear distance increases (that is, the stroke of the piston 3b increases) and the volume of the combustion chamber decreases.

  On the other hand, contrary to the above, when the drive shaft 87b of the actuator 87 moves from the high compression ratio position to the low compression ratio position, the rotation shaft portion 85a rotates in the clockwise direction in the drawing, and accordingly, eccentricity occurs. As the shaft portion 85b moves upward, the entire control link 84 is pushed up. As a result, the lower link 83 rotates counterclockwise and the upper link 82 rotates clockwise by an operation opposite to the above. As a result, the linear distance connecting the piston pin 3f and the crank pin 83b when the piston 3b reaches top dead center is shortened (that is, the stroke of the piston 3b is shortened), and the volume of the combustion chamber is increased. The ratio Cr is lowered. As described above, in the variable compression ratio mechanism 80, the compression ratio Cr is changed steplessly between the predetermined maximum value Crmax and the minimum value Crmin described above by changing the rotation angle of the control shaft 85. The

  The variable compression ratio mechanism 80 is provided with a lock mechanism (not shown). When the compression ratio control input U_Cr is set to a failure time value U_Cr_fs, which will be described later, or due to a disconnection or the like. When the compression ratio control input U_Cr is not input to the compression ratio actuator 87, the operation of the variable compression ratio mechanism 80 is locked. That is, change of the compression ratio Cr by the variable compression ratio mechanism 80 is prohibited, and the compression ratio Cr is held at the minimum value Crmin. As described above, the minimum value Crmin is a predetermined failure time value Gcyl_fs as an intake air amount when the valve lift Liftin is held at the minimum value Liftinmin and the cam phase Cain is held at a predetermined lock value. Is set to a value that can be secured.

  Further, the engine 3 is provided with a control angle sensor 27 in the vicinity of the control shaft 85 (see FIG. 2). The control angle sensor 27 sends a detection signal indicating the rotation angle of the control shaft 85 to the ECU 2. Output. The ECU 2 calculates the compression ratio Cr based on the detection signal of the control angle sensor 27. In the present embodiment, the control angle sensor 27 corresponds to the operation state parameter detection unit and the load parameter detection unit, and the compression ratio Cr corresponds to the operation state parameter and the load parameter.

  Further, as shown in FIG. 2, an accelerator opening sensor 28 and an ignition switch (hereinafter referred to as “IG · SW”) 29 are connected to the ECU 2. The accelerator opening sensor 28 outputs to the ECU 2 a detection signal indicating the depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle. The IG / SW 29 is turned ON / OFF by operating an ignition key (not shown), and outputs a signal indicating the ON / OFF state to the ECU 2.

  The ECU 2 is composed of a microcomputer comprising a CPU, RAM, ROM, I / O interface (all not shown), and the detection signals of the various sensors 20 to 28 described above and ON / OFF of the IG / SW 29. In accordance with the signal or the like, the operating state of the engine 3 is determined and various controls are executed. Specifically, the ECU 2 executes fuel injection control and ignition timing control according to the operating state, as will be described later. In addition, the valve lift Liftin and the cam phase Cain are controlled via the variable valve lift mechanism 50 and the variable cam phase mechanism 70, respectively, and the compression ratio Cr is controlled via the variable compression ratio mechanism 80.

  In the present embodiment, the ECU 2 includes an operation state parameter detection unit, a load parameter detection unit, a first failure determination unit, a second failure determination unit, a drive unit, an intake air amount calculation unit, an engine speed detection unit, and a maximum intake rate. It corresponds to an air amount calculating means, an ignition timing determining means, and a failure target rotational speed setting means.

  Next, the control apparatus 1 of this embodiment is demonstrated. The control device 1 includes a fuel injection controller 100 (see FIG. 11) that performs fuel injection control, and an ignition timing controller 120 (see FIG. 16) that executes ignition timing control. Specifically, the ECU 2 is configured.

  First, the fuel injection controller 100 will be described. The fuel injection controller 100 calculates a fuel injection amount TOUT (fuel amount) for each fuel injection valve 10 as described below. As shown in FIG. 11, the first and second estimated intake air amounts are calculated. Sections 101 and 102, transition coefficient calculation section 103, amplification elements 104 and 105, addition element 106, amplification element 107, air-fuel ratio correction coefficient calculation section 108, total correction coefficient calculation section 109, multiplication element 110, and fuel adhesion correction section 111 It has.

  As will be described below, the first estimated intake air amount calculation unit 101 calculates the first estimated intake air amount Gcyl_vt according to the engine speed NE, the valve lift Liftin, the cam phase Cain, and the compression ratio Cr.

  Specifically, first, a basic estimated intake air amount Gcyl_vt_base is calculated by searching a map shown in FIG. 12 according to the engine speed NE and the valve lift Liftin. In the figure, NE1 to NE3 are predetermined values of the engine speed NE that satisfy the relationship NE1 <NE2 <NE3, and this is the same in the following description.

  In this map, when NE = NE1 or NE2, the basic estimated intake air amount Gcyl_vt_base is set to a larger value as the valve lift Liftin is larger in a region where the valve lift Liftin is smaller, and the valve lift Liftin is closer to the maximum value Liftinmax. In the region, the larger the valve lift Liftin, the smaller the value is set. This is because, in the low / medium rotation range, the valve lift Liftin becomes a larger value in the region close to the maximum value Liftinmax, and the opening time of the intake valve 4 becomes longer, so that the charging efficiency is reduced due to the return of intake air. Because. Further, the basic estimated intake air amount Gcyl_vt_base is set to a larger value as the valve lift Liftin is larger when NE = NE3. This is because, in the high rotation range, even if the valve lift Liftin is large, the intake air is less likely to blow back due to the inertial force of the intake air. Therefore, the larger the valve lift Liftin, the higher the charging efficiency.

  Further, the correction coefficient K_gcyl_vt is calculated by searching the map shown in FIG. 13 according to the engine speed NE and the cam phase Cain. In this map, when NE = NE1 or NE2, the correction coefficient K_gcyl_vt is set to a smaller value when the cam phase Cain is close to the most retarded value Cainrt, and is set to a smaller value when the cam phase Cain is closer to the most retarded value Cainrt. In the region, the cam phase Cain is set to a smaller value as the value is on the most advanced angle value Cainad side. This is because, in the low / medium rotation range, in the region where the cam phase Cain is close to the most retarded angle value Cainrt, the closer the valve timing is to the most retarded angle value Cainrt, the later the closing timing of the intake valve 4 is. This is because the charging efficiency is reduced due to the increase in internal EGR amount accompanying the increase in valve overlap as the cam phase Cain is closer to the most advanced value Cainad in other regions. is there. When NE = NE3, the correction coefficient K_gcyl_vt is set to a constant value (value 1) when the cam phase Cain is close to the most retarded angle value Cainrt, and the cam phase Cain is the most advanced angle in other regions. The smaller the value on the value Cainad side, the smaller the value is set. This is because, in the high rotation range, even if the cam phase Cain is close to the most advanced angle value Cainad, the intake air blow-back is less likely to occur due to the inertial force of the intake air described above.

  Further, the compression ratio correction coefficient K_gcyl_cr is calculated by searching the table shown in FIG. 14 according to the compression ratio Cr. In this table, the compression ratio correction coefficient K_gcyl_cr is set to a larger value as the compression ratio Cr is higher. This is because in the variable compression ratio mechanism 80, the higher the compression ratio Cr, the longer the stroke of the piston 3b and the greater the displacement.

  Then, using the basic estimated intake air amount Gcyl_vt_base, the correction coefficient K_gcyl_vt, and the compression ratio correction coefficient K_gcyl_cr calculated as described above, the first estimated intake air amount Gcyl_vt is calculated by the following equation (1).

Further, the transfer coefficient calculation unit 103 calculates the transfer coefficient Kg as follows. First, the estimated flow rate Gin_vt (unit: g / sec) is calculated by the following equation (2) using the first estimated intake air amount Gcyl_vt calculated by the first estimated intake air amount calculation unit 101 and the engine speed NE.
Gin_vt = 2 · Gcyl_vt · NE / 60 (2)

  Next, the transition coefficient Kg is calculated by searching the table shown in FIG. 15 according to the estimated flow rate Gin_vt. In the figure, Gin1 and Gin2 are predetermined values that satisfy the relationship of Gin1 <Gin2. In the range of Gin_vt ≦ Gin1, the predetermined value Gin1 is a second estimated value whose reliability of the first estimated intake air amount Gcyl_vt will be described later due to the resolution of the airflow sensor 22 because the air flow rate in the intake passage 12a is small. The value is set to exceed the reliability of the intake air amount Gcyl_afm. Further, the predetermined value Gin2 is a value such that the reliability of the second estimated intake air amount Gcyl_afm exceeds the reliability of the first estimated intake air amount Gcyl_vt because the air flow rate in the intake passage 12a is large in the range of Gin2 ≦ Gin_vt. Is set to Furthermore, in this table, the transition coefficient Kg is set to a value of 0 in the range of Gin_vt ≦ Gin1, and to a value of 1 in the range of Gin2 ≦ Gin_vt, and values 0 and 1 in the range of Gin1 <Gin_vt <Gin2. And a value proportional to the estimated flow rate Gin_vt. The reason for this will be described later.

On the other hand, the second estimated intake air amount calculation unit 102 calculates the second estimated intake air amount Gcyl_afm (unit: g) by the following equation (3) based on the air flow rate Gin and the engine speed NE.
Gcyl_afm = Gin · 60 / (2 · NE) (3)

The amplification elements 104 and 105 calculate values obtained by amplifying the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm calculated as described above by (1−Kg) and Kg times, respectively. Then, in the addition element 106, the calculated intake air amount Gcyl is calculated by the weighted average calculation of the following equation (4) based on the value thus amplified.
Gcyl = Kg · Gcyl_afm + (1−Kg) · Gcyl_vt (4)

  As is apparent from the equation (4), when Kg = 0, that is, in the above-described range of Gin_vt ≦ Gin1, Gcyl = Gcyl_vt, and when Kg = 1, that is, in the range of Gin2 ≦ Gin_vt, Gcyl = When Gcyl_afm and 0 <Kg <1, that is, in the range of Gin1 <Gin_vt <Gin2, the degree of weighting of the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm in the calculated intake air amount Gcyl is the value of the transition coefficient Kg. Determined by.

Further, the amplifying element 107 calculates the basic fuel injection amount Tcyl_bs from the calculated intake air amount Gcyl (intake air amount) by the following equation (5).
Tcyl_bs = Kgt · Gcyl (5)
Here, Kgt is a conversion coefficient set in advance for each fuel injection valve 10.

  The air-fuel ratio correction coefficient calculation unit 108 calculates an air-fuel ratio correction coefficient KSTR by a control algorithm (not shown) including a predetermined feedback control algorithm according to the detected air-fuel ratio KACT and the target air-fuel ratio KCMD.

  Further, the total correction coefficient calculation unit 109 calculates various correction coefficients by searching a map and a table (not shown) according to various parameters representing operating conditions such as the engine water temperature TW and the intake air temperature TA, A total correction coefficient KTOTAL is calculated by multiplying these various correction coefficients.

In the multiplication element 110, the required fuel injection amount Tcyl is calculated by the following equation (6).
Tcyl = Tcyl_bs · KSTR · KTOTAL (6)

  Furthermore, the fuel adhesion correction unit 111 calculates the fuel injection quantity TOUT by performing a predetermined fuel adhesion correction process on the required fuel injection quantity Tcyl calculated as described above. Then, the fuel injection valve 10 is controlled so that the fuel injection timing and the valve opening time of the fuel injection valve 10 become values based on the fuel injection amount TOUT.

  As shown in the above equations (5) and (6), in the fuel injection controller 100, the fuel injection amount TOUT is calculated based on the calculated intake air amount Gcyl, and as shown in the equation (4), Kg = 0. Sometimes Gcyl = Gcyl_vt, and when Kg = 1, Gcyl = Gcyl_afm. As described above, in the range of Gin_vt ≦ Gin1, the reliability of the first estimated intake air amount Gcyl_vt exceeds the reliability of the second estimated intake air amount Gcyl_afm. Therefore, in such a range, the fuel injection amount TOUT is more increased. This is to ensure good calculation accuracy by calculating based on the highly reliable first estimated intake air amount Gcyl_vt. Further, in the range of Gin2 ≦ Gin_vt, since the air flow rate in the intake passage 12a is large, the reliability of the second estimated intake air amount Gcyl_afm exceeds the reliability of the first estimated intake air amount Gcyl_vt. This is to ensure good calculation accuracy by calculating the fuel injection amount TOUT based on the second estimated intake air amount Gcyl_afm with higher reliability.

  When 0 <Kg <1, the degree of weighting of the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm in the calculated intake air amount Gcyl is determined by the value of the transition coefficient Kg. This is considered to occur when a torque step occurs due to a large difference between the values of the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm when switching directly from one of Gcyl_vt and Gcyl_afm to the other. This is to avoid it. That is, as described above, in the range of Gin1 <Gin_vt <Gin2 where the transition coefficient Kg is 0 <Kg <1, the transition coefficient Kg is set to a value proportional to the estimated flow rate Gin_vt. When Gin_vt changes between Gin1 and Gin2, the transition coefficient Kg gradually changes accordingly, whereby the calculated intake air amount Gcyl gradually changes from one value of Gcyl_vt and Gcyl_afm to the other value. Become. As a result, generation of a torque step can be avoided.

  Next, the ignition timing controller 120 (ignition timing determination means) will be described with reference to FIG. As shown in the figure, a part of the ignition timing controller 120 is configured in the same manner as the fuel injection controller 100 described above. Therefore, the same components are denoted by the same reference numerals and description thereof is omitted. To do. The ignition timing controller 120 calculates an ignition timing Iglog as described below, and includes first and second estimated intake air amount calculation units 101 and 102, a transition coefficient calculation unit 103, amplification elements 104 and 105, and an addition element. 106, a maximum estimated intake air amount calculation unit 121, a division element 122, a basic ignition timing calculation unit 123, an ignition correction value calculation unit 124, and an addition element 125.

  In the maximum estimated intake air amount calculation unit 121 (maximum intake air amount calculation means), as described below, the maximum estimated intake air amount Gcyl_max (maximum intake air amount) according to the engine speed NE, cam phase Cain, and compression ratio Cr. Is calculated. Specifically, first, the basic value Gcyl_max_base of the maximum estimated intake air amount is calculated by searching the table shown in FIG. 17 according to the engine speed NE. In this table, the basic value Gcyl_max_base is set to a larger value as the engine speed NE is higher in the low to medium speed range, and is set to a smaller value as the engine speed NE is higher in the high speed range. In addition, the maximum value is set at a predetermined value in the middle rotation range. This is because, from the viewpoint of drivability, the intake system is configured so that the charging efficiency is maximized when the predetermined value is in the middle rotation range.

  Further, the correction coefficient K_gcyl_max is calculated by searching the map shown in FIG. 18 according to the engine speed NE and the cam phase Cain. In this map, when NE = NE1 or NE2, the correction coefficient K_gcyl_max is set to a smaller value when the cam phase Cain is close to the most retarded value Cainrt, and is set to a smaller value when the cam phase Cain is closer to the most retarded value Cainrt. In the region, the cam phase Cain is set to a smaller value as the value is on the most advanced angle value Cainad side. Further, when NE = NE3, the correction coefficient K_gcyl_max is set to a constant value (value 1) when the cam phase Cain is close to the most retarded angle value Cainrt, and the cam phase Cain is the most advanced angle in other regions. The smaller the value on the value Cainad side, the smaller the value is set. The reason why the correction coefficient K_gcyl_max is set in this manner is the same as the reason described in the description of the map of FIG. 13 used for calculating the correction coefficient K_gcyl_vt.

  Further, as described above, the compression ratio correction coefficient K_gcyl_cr is calculated by searching the table shown in FIG. 14 according to the compression ratio Cr. Then, using the basic value Gcyl_max_base of the maximum estimated intake air amount calculated as described above, the correction coefficient K_gcyl_max, and the compression ratio correction coefficient K_gcyl_cr, the maximum estimated intake air amount Gcyl_max is calculated by the following equation (7).

On the other hand, in the division element 122, the normalized intake air amount Kgcyl (ratio) is calculated by the following equation (8).
Kgcyl = Gcyl / Gcyl_max (8)

  Further, as described below, the basic ignition timing calculation unit 123 searches the basic ignition timing map according to the normalized intake air amount Kgcyl, the engine speed NE, the cam phase Cain, and the compression ratio Cr, so that the basic ignition timing is calculated. The time Iglog_map is calculated. In this case, as a basic ignition timing map, one set of maps for Cr = Crmin and one set of maps for Cr = Crmax are prepared, and one set for Cr = Crmin is shown in FIG. The map for Cr = Crmin & Cain = Cainrt, the map for Cr = Crmin & Cain = Cainad shown in FIG. 20, and Cr = Crmin, and the cam phase Cain is between the most retarded angle value Cainrt and the most advanced angle value Cainad. And a plurality of maps (not shown) set corresponding to the values of the cam phases Cain in a plurality of stages. Although not shown, the set of maps for Cr = Crmax is configured in the same manner as the set of maps for Cr = Crmin.

  In the above basic ignition timing map search, a plurality of values are selected based on the values of the normalized intake air amount Kgcyl, the engine speed NE, the cam phase Cain, and the compression ratio Cr, and an interpolation operation of the plurality of selected values is performed. The basic ignition timing Iglog_map is calculated.

  As described above, the basic ignition timing calculation unit 123 uses the normalized intake air amount Kgcyl as a parameter for setting the map value of the basic ignition timing map, and the reason is as follows. That is, when the map value of the basic ignition timing map is set using the calculated intake air amount Gcyl as a parameter instead of the normalized intake air amount Kgcyl as in the prior art, for example, the basic ignition timing map shown in FIG. 21 is obtained. As shown in the figure, in this basic ignition timing map, the maximum setting value of the calculated intake air amount Gcyl is different from each other, and the region where the calculated intake air amount Gcyl is large (region surrounded by an ellipse), that is, a high load at which knocking starts to occur. The number of map values set in the region (the number of grid points indicated by black circles) varies for each engine speed NE. This is because the intake air charging efficiency in the cylinder 3a changes according to the engine speed NE, and the maximum value of the intake air amount in the high load region where knocking begins to occur also depends on the engine speed NE. Because it changes.

  On the other hand, in the basic ignition timing map of the basic ignition timing calculation unit 123, since the normalized intake air amount Kgcyl is used as a parameter instead of the calculated intake air amount Gcyl, knocking occurs as shown in FIGS. The number of map values can be set to the same number between the set values NE1 to NE3 of the engine speed even in a high load range where Kgcyl includes a value of 1, and the setting data It can be seen that the number can be reduced from the map of FIG. That is, by using the normalized intake air amount Kgcyl as a parameter instead of the calculated intake air amount Gcyl as in this embodiment, the storage capacity of the ROM of the ECU 2 can be reduced, and the manufacturing cost can be reduced accordingly. It is.

  The ignition correction value calculation unit 124 calculates various correction values by searching a map and a table (not shown) according to the intake air temperature TA, the engine water temperature TW, the target air-fuel ratio KCMD, and the like. Based on various correction values, an ignition correction value Diglog is calculated.

Further, in the addition element 125, the ignition timing Iglog is calculated by the following equation (9).
Iglog = Ilog_map + Diglog (9)

  The spark plug 11 is controlled to discharge at a discharge timing corresponding to the ignition timing Iglog.

  Hereinafter, the fuel injection control process executed by the ECU 2 will be described with reference to FIG. This process calculates the fuel injection amount TOUT for each fuel injection valve 10 and is executed in synchronization with the generation timing of the TDC signal.

  First, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), a basic fuel injection amount Tcyl_bs is calculated. Specifically, the basic fuel injection amount Tcyl_bs is calculated as shown in FIG. That is, first, in step 10, the second estimated intake air amount Gcyl_afm is calculated by the above-described equation (3).

  Next, in step 11, the first estimated intake air amount Gcyl_vt is calculated by the method described above. That is, the basic estimated intake air amount Gcyl_vt_base is calculated by searching the map shown in FIG. 12 according to the engine speed NE and the valve lift Liftin, and shown in FIG. 13 according to the engine speed NE and the cam phase Cain. A correction coefficient K_gcyl_vt is calculated by searching the map, and a compression ratio correction coefficient K_gcyl_cr is calculated by searching the table shown in FIG. 14 according to the compression ratio Cr. Then, based on these three values Gcyl_vt_base, K_gcyl_vt, K_gcyl_cr, the first estimated intake air amount Gcyl_vt is calculated by the above-described equation (1).

  Next, in step 12, the estimated flow rate Gin_vt is calculated by the above-described equation (2). Thereafter, the process proceeds to step 13 to determine whether or not the variable mechanism failure flag F_VDNG is “1”.

  The variable mechanism failure flag F_VDNG is set to “1” when it is determined that at least one of the variable valve lift mechanism 50, the variable cam phase mechanism 70, and the variable compression ratio mechanism 80 has failed in the failure determination process described later. When both are determined to be normal, each is set to “0”. In the following description, the variable valve lift mechanism 50, the variable cam phase mechanism 70, and the variable compression ratio mechanism 80 are collectively referred to as “three variable mechanisms”.

  If the determination result in step 13 is NO and all the three variable mechanisms are normal, the process proceeds to step 14 to determine whether or not the air flow sensor failure flag F_AFMNG is “1”. The air flow sensor failure flag F_AFMNG is set to “1” when it is determined that the air flow sensor 22 has failed in a failure determination process described later, and is set to “0” when it is determined that the air flow sensor 22 is normal.

  When the determination result of step 14 is NO and the air flow sensor 22 is normal, the process proceeds to step 15 and, as described above, the transition coefficient Kg is searched by searching the table shown in FIG. 15 according to the estimated flow rate Gin_vt. calculate.

  On the other hand, if the decision result in the step 14 is YES and the air flow sensor 22 is out of order, the process proceeds to a step 16 and the transition coefficient Kg is set to a value 0.

  In step 17 following step 15 or 16, the calculated intake air amount Gcyl is calculated by the above-described equation (4). Next, in step 18, the basic fuel injection amount Tcyl_bs is set to the product Kgt · Gcyl of the conversion coefficient and the calculated intake air amount, and then this process is terminated.

  On the other hand, if the determination result in step 13 is YES and it is determined that at least one of the three variable mechanisms has failed, the process proceeds to step 19 where the calculated intake air amount Gcyl is set to the predetermined failure value Gcyl_fs described above. To do. Next, after executing step 18 described above, the present process is terminated.

  Returning to FIG. 23, in step 1, the basic fuel injection amount Tcyl_bs is calculated as described above, and then the process proceeds to step 2 where the total correction coefficient KTOTAL is calculated. Specifically, as described above, various tables and maps are searched for according to various operation parameters (for example, intake air temperature TA, atmospheric pressure PA, engine water temperature TW, accelerator pedal opening AP, etc.). The total correction coefficient KTOTAL is calculated by multiplying these various correction coefficients with each other.

  Next, the routine proceeds to step 3, where a target air-fuel ratio KCMD is calculated by searching a map (not shown) according to the accelerator opening AP and the calculated intake air amount Gcyl. This target air-fuel ratio KCMD is basically set to the theoretical air-fuel ratio (14.5) in order to keep the exhaust gas purification performance of the catalyst device in a good state.

  Next, the routine proceeds to step 4 where the air-fuel ratio correction coefficient KSTR is calculated by a predetermined control algorithm including a feedback control algorithm in accordance with the target air-fuel ratio KCMD and the detected air-fuel ratio KACT.

  Next, the routine proceeds to step 5, where the required fuel injection amount Tcyl is calculated by the above-described equation (6). Thereafter, in step 6, as described above, the fuel injection amount TOUT is calculated by applying a predetermined fuel adhesion correction process to the required fuel injection amount Tcyl. Then, this process is complete | finished. Thereby, the fuel injection valve 10 is controlled so that the fuel injection timing and the valve opening time of the fuel injection valve 10 become values based on the fuel injection amount TOUT.

  Next, the ignition timing control process executed by the ECU 2 will be described with reference to FIG. This process is to calculate the ignition timing Iglog as described below, and is executed following the fuel injection control process described above in synchronization with the generation timing of the TDC signal.

  In this process, first, in step 30, it is determined whether or not the aforementioned variable mechanism failure flag F_VDNG is “1”. When the determination result is NO and all the three variable mechanisms are normal, the process proceeds to step 31 to determine whether or not the engine start flag F_ENGSTART is “1”.

  The engine start flag F_ENGSTART is set in a determination process (not shown) by determining whether engine start control is being performed, that is, cranking, according to the output signal of the engine speed NE and the IG / SW 29. Specifically, “1” is set when the engine start control is being performed, and “0” is set otherwise.

  If the decision result in the step 31 is YES and the engine start control is being performed, the process proceeds to a step 32, the ignition timing Iglog is set to a predetermined start time value Ig_crk (for example, BTDC 10 °), and the present process is ended.

  On the other hand, when the determination result of step 31 is NO and the engine start control is not being performed, the routine proceeds to step 33, where it is determined whether or not the accelerator opening AP is smaller than a predetermined value APREF. The predetermined value APREF is for determining that the accelerator pedal is not depressed, and is set to a value (for example, 1 °) that can determine that the accelerator pedal is not depressed.

  If the determination result is YES and the accelerator pedal is not depressed, the routine proceeds to step 34, where the catalyst warm-up control execution time Tcat, which is an elapsed time immediately after the start of the engine 3, is from a predetermined value Tcatlmt (for example, 30 sec). Determine whether it is small. This catalyst warm-up control is for rapidly activating the catalyst in the catalyst device provided in the exhaust pipe 13 after the engine is started. If the determination result is YES and Tcat <Tcatlmt, it is determined that the catalyst warm-up control should be executed, and the process proceeds to step 35 to calculate the catalyst warm-up value Ig_ast. Specifically, the catalyst warm-up value Ig_ast is calculated by a response designation control algorithm (sliding mode control algorithm or backstepping control algorithm) of the following equations (10) to (12).

  In addition, each discrete data with the symbol (k) in the expressions (10) to (12) is data sampled (or calculated) in synchronization with a predetermined control period (in this embodiment, the generation period of the TDC signal). The symbol k represents the order of the sampling cycle of each discrete data. For example, the symbol k indicates a value sampled at the current control timing, and the symbol k-1 indicates a value sampled at the previous control timing. This also applies to the following discrete data. In the following description, the symbol (k) in each discrete data is omitted as appropriate.

  In Expression (10), Ig_ast_base represents a predetermined catalyst warm-up reference ignition timing (for example, BTDC 5 °), and Krch and Kadp represent a predetermined feedback gain. Also, σ is a switching function defined as in equation (11). In the equation (11), “pole” is a response designation parameter set so that the relationship of −1 <pole <0 is established, and “Elast” is a tracking error calculated by the equation (12). In Expression (12), NE_ast is a predetermined target engine speed for warming up the catalyst (for example, 1800 rpm). By the control algorithm described above, the catalyst warm-up value Ig_ast is calculated as a value that converges the engine speed NE to the catalyst warm-up target speed NE_ast.

  Next, the routine proceeds to step 36, where the ignition timing Iglog is set to the catalyst warm-up value Ig_ast, and then this process is terminated.

  On the other hand, when the determination result in step 33 or 34 is NO, that is, when Tcat ≧ Tcatlmt, or when the accelerator pedal is depressed, the routine proceeds to step 37, where the normal ignition timing control process is executed.

  Specifically, the normal ignition timing control process is executed as shown in FIG. First, at step 50, the maximum estimated intake air amount Gcyl_max is calculated by the method described above. That is, the basic value Gcyl_max_base of the maximum estimated intake air amount is calculated by searching the table shown in FIG. 17 according to the engine speed NE, and the map shown in FIG. 18 according to the engine speed NE and the cam phase Cain. Is calculated, and the compression ratio correction coefficient K_gcyl_cr is calculated by searching the table shown in FIG. 14 according to the compression ratio Cr. Then, based on the three Gcyl_max_base, K_gcyl_max, and K_gcyl_cr calculated as described above, the maximum estimated intake air amount Gcyl_max is calculated by the above-described equation (7).

  Next, at step 51, the normalized intake air amount Kgcyl is calculated by the above-described equation (8). Thereafter, in step 52, the basic ignition timing Iglog_map is calculated by the method described above. That is, according to the normalized intake air amount Kgcyl, the engine speed NE, the cam phase Cain, and the compression ratio Cr, a basic ignition timing map such as FIGS. 19 and 20 is searched to select a plurality of values and to select the plurality of selections. The basic ignition timing Iglog_map is calculated by value interpolation.

  Next, in step 53, the ignition correction value Diglog is calculated by the method described above. That is, various correction values are calculated by searching a map and a table (not shown) according to the intake air temperature TA, the engine water temperature TW, the target air-fuel ratio KCMD, and the like, and the ignition correction value is calculated based on these various correction values. Calculate the Dialog. Next, at step 54, the ignition timing Iglog is calculated by the aforementioned equation (9).

  Returning to FIG. 24, in step 37, after executing the normal ignition timing control process as described above, the present process is terminated.

 On the other hand, if the decision result in the step 30 is YES and at least one of the three variable mechanisms has failed, the process proceeds to a step 38 to calculate a failure value Ig_fs. Specifically, the failure time value Ig_fs is calculated by a response designating control algorithm (sliding mode control algorithm or backstepping control algorithm) represented by the following equations (13) to (15).

In the above equation (13), Ig_fs_base represents a predetermined failure ignition reference ignition timing (for example, TDC ± 0 °), and Krch ^# and Kadp ^# represent a predetermined feedback gain. Also, σ ^# is a switching function defined as in equation (14). In equation (14), pole ^# is a response designation parameter set so that the relationship of −1 <pole ^# <0 is established, and Enfs is a tracking error calculated by equation (15). In Expression (15), NE_fs is a predetermined failure target rotational speed (for example, 2000 rpm). By the above control algorithm, the failure value Ig_fs is calculated as a value for converging the engine speed NE to the failure target speed NE_fs.

  Next, the routine proceeds to step 39, where the ignition timing Iglog is set to the failure time value Ig_fs, and then this processing is terminated.

  Hereinafter, the variable mechanism control process executed by the ECU 2 will be described with reference to FIG. This process calculates three control inputs U_Liftin, U_Cain, U_Cr for controlling the three variable mechanisms, respectively, and is executed at a predetermined control cycle (for example, 5 msec).

  In this process, first, in step 60, it is determined whether or not the aforementioned variable mechanism failure flag F_VDNG is “1”. When the determination result is NO and all the three variable mechanisms are normal, the routine proceeds to step 61, where it is determined whether or not the engine start flag F_ENGSTART described above is “1”.

  If the determination result is YES and the engine start control is being performed, the routine proceeds to step 62, where the target valve lift Liftin_cmd is calculated by searching the table shown in FIG. 27 according to the engine coolant temperature TW.

  In this table, the target valve lift Liftin_cmd is set to a larger value as the engine coolant temperature TW is lower in the range where the engine coolant temperature TW is higher than the predetermined value TWREF1, and to the predetermined value Liftinref in the range of TW ≦ TWREF1. Is set. This is for compensating for the friction of the variable valve lift mechanism 50 when the engine coolant temperature TW is low.

  Next, at step 63, the target cam phase Cain_cmd is calculated by searching the table shown in FIG. 28 according to the engine coolant temperature TW.

  In this table, the target cam phase Cain_cmd is set to a more retarded value as the engine coolant temperature TW is lower in the range where the engine coolant temperature TW is higher than the predetermined value TWREF2, and in the range of TW ≦ TWREF2, The value Cainref is set. This is because when the engine water temperature TW is low, the cam phase Cain is controlled to be retarded as compared with the case where the engine water temperature TW is high, and the valve overlap is reduced to increase the intake air flow rate and stabilize combustion. Because.

  Next, at step 64, the target compression ratio Cr_cmd is set to a predetermined starting value Cr_cmd_crk. This starting value Cr_cmd_crk is set to a value on the low compression ratio side that can increase the engine speed NE during cranking and suppress the generation of unburned HC.

  Next, the routine proceeds to step 65, where the lift control input U_Liftin is calculated by the target value filter type two-degree-of-freedom sliding mode control algorithm expressed by the following equations (16) to (19).

  In the equation (16), Krch_lf represents a predetermined reaching law gain, Kadp_lf represents a predetermined adaptive law gain, and σ_lf is a switching function defined as in the expression (17). In the equation (17), pole_lf is a response specifying parameter set so that the relationship of -1 <pole_lf <0 is established, and E_lf is a tracking error calculated by the equation (18). In the equation (18), Liftin_cmd_f is a filter value of the target valve lift, and is calculated by the first-order lag filter algorithm shown in the equation (19). In the equation (19), pole_f_lf is a target value filter setting parameter that is set so that the relationship of -1 <pole_f_lf <0 is established.

  Next, the process proceeds to step 66, where the phase control input U_Cain is calculated by the target value filter type two-degree-of-freedom sliding mode control algorithm expressed by the following equations (20) to (23).

  In equation (20), Krch_ca represents a predetermined reaching law gain, Kadp_ca represents a predetermined adaptive law gain, and σ_ca is a switching function defined as in expression (21). In the equation (21), pole_ca is a response specifying parameter set so that the relationship of -1 <pole_ca <0 is established, and E_ca is a tracking error calculated by the equation (22). In the equation (22), Cain_cmd_f is a filter value of the target cam phase, and is calculated by the first order lag filter algorithm shown in the equation (23). In the equation (23), pole_f_ca is a target value filter setting parameter that is set so that the relationship of -1 <pole_f_ca <0 is established.

  Next, the process proceeds to step 67, and the compression ratio control input U_Cr is calculated by the target value filter type two-degree-of-freedom sliding mode control algorithm expressed by the following equations (24) to (27).

  In Expression (24), Krch_cr represents a predetermined reaching law gain, Kadp_cr represents a predetermined adaptive law gain, and σ_cr is a switching function defined as Expression (25). In the equation (25), pole_cr is a response designation parameter set so that the relationship of -1 <pole_cr <0 is established, and E_cr is a follow-up error calculated by the equation (26). In the equation (26), Cr_cmd_f is a filter value of the target compression ratio, and is calculated by the first order lag filter algorithm shown in the equation (27). In the equation (27), pole_f_cr is a target value filter setting parameter that is set so that the relationship of −1 <pole_f_cr <0 is established.

  After the compression ratio control input U_Cr is calculated in the above step 67, this process is terminated.

  On the other hand, when the determination result of step 61 is NO and the engine start control is not being performed, the routine proceeds to step 68, where it is determined whether or not the accelerator pedal opening AP is smaller than a predetermined value APREF. If the determination result is YES and the accelerator pedal is not depressed, the routine proceeds to step 69, where it is determined whether or not the catalyst warm-up control execution time Tcat is smaller than a predetermined value Tcatlmt.

  If the determination result is YES and Tcat <Tcatlmt, it is determined that the catalyst warm-up control should be executed, and the process proceeds to step 70, where the target valve lift Liftin_cmd is set according to the catalyst warm-up control execution time Tcat and the engine water temperature TW. Then, it is calculated by searching the map shown in FIG. In the figure, TW1 to TW3 indicate predetermined values of the engine coolant temperature TW that satisfy the relationship of TW1 <TW2 <TW3, and this also applies to the following description.

  In this map, the target valve lift Liftin_cmd is set to a larger value as the engine coolant temperature TW is lower. This is because the lower the engine water temperature TW, the longer the time required for the activation of the catalyst. Therefore, by increasing the exhaust gas volume, the time required for the activation of the catalyst is shortened. In addition, in this map, the target valve lift Liftin_cmd is set to a larger value as the execution time Tcat is longer while the execution time Tcat of the catalyst warm-up control is shorter, and after the execution time Tcat has elapsed to some extent. Is set to a smaller value as the execution time Tcat is longer. This is because when the engine 3 warms up as the execution time Tcat elapses and the friction decreases, the ignition timing is used to maintain the engine speed NE at the target value unless the intake air amount is reduced. This is to avoid the excessively retarded control and the combustion state becoming unstable.

  Next, at step 71, the target cam phase Cain_cmd is calculated by searching the map shown in FIG. 30 according to the catalyst warm-up control execution time Tcat and the engine coolant temperature TW.

  In this map, the target cam phase Cain_cmd is set to a more advanced value as the engine coolant temperature TW is lower. This is because, as the engine water temperature TW is lower, the time required for catalyst activation becomes longer as described above, so the pumping loss is reduced and the intake air amount is increased, thereby reducing the time required for catalyst activation. It is to do. In addition, in this map, the target cam phase Cain_cmd is set to a more retarded value as the execution time Tcat is longer while the catalyst warm-up control execution time Tcat is shorter. After elapses, the value is set to a more advanced value as the execution time Tcat is longer. This is due to the same reason as described in FIG.

  Next, in step 72, the target compression ratio Cr_cmd is set to a predetermined warm-up control value Cr_cmd_ast. This warm-up control value Cr_cmd_ast is set to a value on the low compression ratio side that can reduce the thermal efficiency and increase the exhaust gas temperature in order to shorten the time required for the activation of the catalyst.

  Subsequent to step 72, as described above, after executing steps 65 to 67, the present process is terminated.

  On the other hand, when the determination result of step 68 or 69 is NO, that is, when Tcat ≧ Tcatlmt, or when the accelerator pedal is depressed, the routine proceeds to step 73, where the target valve lift Liftin_cmd is set to the engine speed NE and the accelerator opening. It is calculated by searching the map shown in FIG. 31 according to the degree AP. In the figure, AP1 to AP3 indicate predetermined values of the accelerator opening AP at which the relationship of AP1 <AP2 <AP3 is established, and this also applies to the following description.

  In this map, the target valve lift Liftin_cmd is set to a larger value as the engine speed NE is higher or the accelerator pedal opening AP is larger. This is because the higher the engine speed NE or the greater the accelerator pedal opening AP, the greater the required output for the engine 3 and the greater the required intake air amount.

  Next, at step 74, the target cam phase Cain_cmd is calculated by searching the map shown in FIG. 32 according to the engine speed NE and the accelerator pedal opening AP. In this map, the target cam phase Cain_cmd is set to a value on the advance side when the accelerator pedal opening AP is small and in the middle rotation range, compared to other times. This is because in such an operation state, it is necessary to reduce the internal EGR amount and the pumping loss.

  Next, at step 75, the target compression ratio Cr_cmd is calculated by searching the map shown in FIG. 33 according to the engine speed NE and the accelerator pedal opening AP. In this map, the target compression ratio Cr_cmd is set to a smaller value as the engine speed NE is higher or as the accelerator pedal opening AP is larger. This is because the higher the load range, that is, the easier the occurrence of knocking, the lower the compression ratio, thereby preventing the ignition timing from being excessively retarded and avoiding a decrease in combustion efficiency. is there.

  Subsequent to step 75, as described above, after executing steps 65 to 67, the present process is terminated.

 On the other hand, if the decision result in the step 60 is YES and at least one of the three variable mechanisms has failed, the process proceeds to a step 76 where the lift control input U_Liftin is set to a predetermined failure value U_Liftin_fs and the phase control input U_Cain is set to a predetermined value. After setting the compression ratio control input U_Cr to a predetermined failure time value U_Cr_fs and the failure time value U_Cain_fs, this processing is terminated. As a result, as described above, the valve lift Liftin is held at the minimum value Liftinmin, the cam phase Cain is held at the predetermined lock value, and the compression ratio Cr is held at the minimum value Crmin. Can be appropriately executed, and at the same time, a low-speed traveling state can be maintained during traveling.

  Next, the failure determination process for the three variable mechanisms and the airflow sensor 22 executed by the ECU 2 will be described with reference to FIG. This process determines whether or not the three variable mechanisms and the airflow sensor 22 are out of order, and is executed at a predetermined control cycle (for example, 5 msec).

  In this process, first, in step 80, it is determined whether or not the variable valve lift mechanism 50 is in a failure state. Specifically, when the absolute value of the deviation between the valve lift Liftin and the target valve lift Liftin_cmd exceeds a predetermined threshold for a predetermined time or more, or the absolute value of the lift control input U_Liftin exceeds the predetermined value When the state continues for a predetermined time or more, it is determined that the variable valve lift mechanism 50 is in a failure state, and otherwise, it is determined that the variable valve lift mechanism 50 is normal.

  If the determination result is YES and the variable valve lift mechanism 50 is in a failure state, the process proceeds to step 81 to indicate that, and the lift mechanism failure flag F_VDNG1 is set to “1”. On the other hand, if the decision result in the step 80 is NO and the variable valve lift mechanism 50 is normal, the process proceeds to a step 82 to indicate that, and the lift mechanism failure flag F_VDNG1 is set to “0”.

  In step 83 following step 81 or 82, it is determined whether or not the variable cam phase mechanism 70 is in a failure state. Specifically, when the absolute value of the deviation between the cam phase Cain and the target cam phase Cain_cmd exceeds a predetermined threshold for a predetermined time or more, or the absolute value of the phase control input U_Cain is a predetermined threshold. When the state exceeding the value continues for a predetermined time or more, it is determined that the variable cam phase mechanism 70 is in a failure state, and otherwise, it is determined that the variable cam phase mechanism 70 is normal.

  If the determination result is YES and the variable cam phase mechanism 70 is in a failure state, the process proceeds to step 84 to indicate that, and the phase mechanism failure flag F_VDNG2 is set to “1”. On the other hand, if the determination result in step 83 is NO and the variable cam phase mechanism 70 is normal, the process proceeds to step 85 to indicate that, and the phase mechanism failure flag F_VDNG2 is set to “0”.

  In step 86 following step 84 or 85, it is determined whether or not the variable compression ratio mechanism 80 is in a failure state. Specifically, when the absolute value of the deviation between the compression ratio Cr and the target compression ratio Cr_cmd exceeds a predetermined threshold for a predetermined time or longer, or when the absolute value of the compression ratio control input U_Cr is a predetermined value. When the state exceeding the threshold value continues for a predetermined time or more, it is determined that the variable compression ratio mechanism 80 is in a failure state, and otherwise, it is determined that the variable compression ratio mechanism 80 is normal.

  If the determination result is YES and the variable compression ratio mechanism 80 is in a failure state, the process proceeds to step 87 to indicate that, and the compression ratio mechanism failure flag F_VDNG3 is set to “1”. On the other hand, if the determination result in step 86 is NO and the variable compression ratio mechanism 80 is normal, the process proceeds to step 88 to indicate that, and the compression ratio mechanism failure flag F_VDNG3 is set to “0”.

  In step 89 following step 87 or 88, it is determined whether or not any of the above three failure flags F_VDNG1 to 3 is “0”. If the determination result is NO and at least one of the three variable mechanisms has failed, the process proceeds to step 90 to indicate that, and the variable mechanism failure F_VDNG is set to “1”.

  On the other hand, if the determination result in step 89 is NO and all the three variable mechanisms are normal, the process proceeds to step 91 to indicate that, and the variable mechanism failure F_VDNG is set to “0”.

  In step 92 following step 90 or 91, it is determined whether or not the airflow sensor 22 is in a failure state. Specifically, when the air flow sensor 22 is normal, a failure determination table in which the upper limit value and the lower limit value of the second estimated intake air amount Gcyl_afm with respect to the first estimated intake air amount Gcyl_vt are set in advance according to the first estimated intake air amount Gcyl_vt. To search. When the second estimated intake air amount Gcyl_afm is outside the range defined by the search values for the upper limit value and the lower limit value, it is determined that the airflow sensor 22 is in a failure state. It is determined that the sensor 22 is normal.

  If the decision result in the step 92 is YES and the air flow sensor 22 is in a failure state, the process proceeds to a step 93 to indicate that, and the air flow sensor failure flag F_AFMNG is set to “1”, and then this process ends.

  On the other hand, if the determination result in step 92 is NO and the airflow sensor 22 is normal, the process proceeds to step 94 to indicate that, and after setting the airflow sensor failure flag F_AFMNG to “0”, the present process ends. .

  As described above, according to the control device 1 of the present embodiment, the first estimated intake air amount Gcyl_vt is calculated according to the valve lift Liftin, the cam phase Cain, and the compression ratio Cr, and the second estimated intake air amount Gcyl_afm is calculated based on the air flow. It is calculated according to the air flow rate Gin detected by the sensor 22. Then, the calculated intake air amount Gcyl is calculated as a weighted average value of the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm according to the equation (4), and in the range of Gin_vt ≦ Gin1, Gcyl = Gcyl_vt and Gin2 ≦ Gin_vt In this range, Gcyl = Gcyl_afm.

  In the fuel injection control process, the fuel injection amount TOUT is calculated based on the calculated intake amount Gcyl. Therefore, when Gin_vt ≦ Gin1, that is, when the air flow rate in the intake passage 12a is small, the detection signal of the air flow sensor 22 When the reliability is low and the reliability of the first estimated intake air amount Gcyl_vt exceeds the reliability of the second estimated intake air amount Gcyl_afm, the fuel injection amount TOUT is set based on the higher reliability of the first estimated intake air amount Gcyl_vt. It is possible to calculate with high accuracy. When Gin2 ≦ Gin_vt, that is, the air flow rate in the intake passage 12a is large, the reliability of the detection signal of the airflow sensor 22 is high, and the reliability of the second estimated intake air amount Gcyl_afm is the first estimated intake air amount Gcyl_vt. The fuel injection amount TOUT can be accurately calculated based on the second estimated intake air amount Gcyl_afm with higher reliability. As described above, the fuel injection amount TOUT can be accurately calculated even in a low load region where the reliability of the first estimated intake air amount Gcyl_vt exceeds the reliability of the second estimated intake air amount Gcyl_afm, or in the opposite load region. Therefore, the control accuracy of the fuel injection control, that is, the control accuracy of the air-fuel ratio control can be improved. As a result, fuel consumption and exhaust gas characteristics can be improved.

  Furthermore, the degree of weighting of the first and second estimated intake air amounts Gcyl_vt, Gcyl_afm in the calculated intake air amount Gcyl is determined by the value of the transition coefficient Kg, and when Gin1 <Gin_vt <Gin2, the transition coefficient Kg is the estimated flow rate Gin_vt. Therefore, when the estimated flow rate Gin_vt changes between Gin1 and Gin2, the transition coefficient Kg gradually changes accordingly, so that the calculated intake air amount Gcyl becomes equal to Gcyl_vt and Gcyl_afm. The value gradually changes from the value on one side to the value on the other side. Accordingly, when the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm are directly switched from one to the other, the difference between the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm is large, so the fuel injection amount TOUT changes. Even when a torque step occurs due to the above, it can be avoided.

  When it is determined that the airflow sensor 22 is in a failure state, Gcyl = Gcyl_vt, and the fuel injection amount TOUT is calculated in accordance with the first estimated intake air amount Gcyl_vt in all load regions. Even when the reliability of the second estimated intake air amount Gcyl_afm is reduced due to the above, the fuel injection amount TOUT can be appropriately calculated according to the first estimated intake air amount Gcyl_vt, and good control accuracy in the fuel injection control can be obtained. It can be secured.

  Further, when it is determined that at least one of the three variable mechanisms is in a failure state, control inputs U_Liftin, U_Cain, U_Cr to the three variable mechanisms are set so that the intake air amount becomes a predetermined failure value Gcyl_fs. All are set to predetermined failure values U_Liftin_fs, U_Cain_fs, and U_Cr_fs, respectively. In addition to this, even when the control inputs U_Liftin, U_Cain, U_Cr are not input to the three variable mechanisms due to disconnection or the like, the valve lift Liftin, the cam phase Cain, and the compression ratio Cr are set by the lock mechanism so that the intake air amount is predetermined. Is maintained at a value such that the failure value Gcyl_fs. As a result, it is possible to avoid an increase in engine output due to an increase in the intake air amount, to avoid the accompanying acceleration, and to continue the operation while avoiding a deceleration due to a decrease in the engine speed NE. The minimum required driving performance in the vehicle can be ensured.

  On the other hand, in the ignition timing control, the basic ignition timing Iglog_map is calculated using an ignition timing map set for the normalized intake air amount Kgcyl and the engine speed NE. Since this normalized intake air amount Kgcyl is calculated as a ratio of the calculated intake air amount Gcyl and the maximum estimated intake air amount Gcyl_max, the calculated intake air amount Gcyl is a value within a range from 0 to 1, and the calculated intake air amount Gcyl is the maximum estimated intake air amount. In a high load region where the value is close to the amount Gcyl_max and knocking occurs, the normalized intake air amount Kgcyl becomes a value near the value 1 including the value 1, and the set values NE1 to NE3 of the engine speed NE different from each other. In contrast, the number of set data of the ignition timing map can be set to the same number with respect to the normalized intake air amount Kgcyl between the set values NE1 to NE3. As a result, the total number of data can be reduced compared with the conventional case where the ignition timing map data is set for the engine speed NE and the intake air amount, and the storage capacity of a storage medium such as a ROM is reduced accordingly. Manufacturing cost can be reduced.

  Further, as described above, since the ignition timing Iglog is calculated using the normalized intake air amount Kgcyl, which is the ratio of the calculated intake air amount Gcyl and the maximum estimated intake air amount Gcyl_max, when Gin_vt ≦ Gin1 or Gin2 ≦ Gin_vt In other words, the ignition timing Iglog is accurately calculated based on the more reliable value even in the load range where one of the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm exceeds the other. be able to. Thereby, the control accuracy of ignition timing control can be improved, and as a result, fuel consumption and combustion stability can be improved.

  Further, as described above, when the calculated intake air amount Gcyl is in the range of Gin1 <Gin_vt <Gin2, when the estimated flow rate Gin_vt changes between Gin1 and Gin2, the value on one side of Gcyl_vt and Gcyl_afm is gradually increased. Therefore, if the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm are directly switched from one to the other, the ignition timing Iglog changes because the difference between the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm is large. Even if a torque step occurs due to the above, it can be avoided.

  When it is determined that the airflow sensor 22 is in a failure state, as described above, Gcyl = Gcyl_vt, and the normalized intake air amount Kgcyl is calculated in accordance with the first estimated intake air amount Gcyl_vt in all load ranges. At the same time, since the ignition timing Iglog is calculated using such normalized intake air amount Kgcyl, even when the reliability of the second estimated intake air amount Gcyl_afm is reduced due to the failure of the air flow sensor 22, the ignition timing Iglog is calculated. Can be appropriately calculated according to the first estimated intake air amount Gcyl_vt, and good control accuracy in the ignition timing control can be ensured.

  Furthermore, as described above, even when it is determined that at least one of the three variable mechanisms is in a failure state, or when the control inputs U_Liftin, U_Cain, U_Cr are not input to the three variable mechanisms due to disconnection, etc. By the mechanism, the valve lift Liftin, the cam phase Cain, and the compression ratio Cr are maintained at values at which the intake air amount becomes a predetermined failure value Gcyl_fs, and the engine rotational speed NE becomes the failure target rotational speed NE_fs. Thus, the failure timing value Iglog_fs of the ignition timing is controlled by the response assignment control algorithm [Equations (13) to (15)]. As a result, acceleration associated with an increase in engine speed NE can be avoided, and at the same time, the operation can be continued while avoiding deceleration due to a decrease in engine speed NE. Can be secured.

  In addition, the throttle valve mechanism of the engine 3 is omitted, and the intake passage 12a is configured to have a large diameter, and accordingly, the flow resistance in the intake passage 12a can be reduced and the charging efficiency can be increased. Manufacturing cost can be reduced.

  The embodiment is an example in which the control device 1 of the present invention is applied to an internal combustion engine 3 for a vehicle. However, the control device of the present invention is not limited to this and is an internal combustion engine for various uses such as for ships and for power generation. Applicable to institutions.

  The embodiment is an example in which the variable valve lift mechanism 50, the variable cam phase mechanism 70, and the variable compression ratio mechanism 80 are used as the variable intake mechanism. However, the variable intake mechanism is not limited to these, and the combustion chamber of the engine 3 is not limited thereto. What is necessary is just to be able to change the amount of intake air sucked in. For example, a conventional throttle valve mechanism may be used as the variable intake mechanism.

  Furthermore, although the embodiment is an example in which the normalized intake air amount Kgcyl as a ratio is set as Kgcyl = Gcyl / Gcyl_max, it may be set as Kgcyl = Gcyl_max / Gcyl. When set in this way, the normalized intake air amount Kgcyl is in a range from 1 to infinity, and the calculated intake air amount Gcyl is close to the maximum estimated intake air amount Gcyl_max, that is, knocking occurs. In the high load range, the normalized intake air amount Kgcyl becomes a value in the vicinity of the value 1 including the value 1, and does not vary between the set values of the plurality of engine speeds NE. As a result, as in the embodiment, the number of set data in the basic ignition timing map can be set to the same number with respect to the normalized intake air amount Kgcyl among the set values of the plurality of engine speeds NE. As a result, the total number of data can be reduced compared with the case where the basic ignition timing map data is set for the engine speed NE and the intake air amount, and the storage capacity of a storage medium such as a ROM is reduced accordingly. Manufacturing costs can be reduced.

  On the other hand, the embodiment is an example in which the first estimated intake air amount Gcyl_vt and the estimated flow rate Gin_vt are calculated according to the engine speed NE, the cam phase Cain, and the compression ratio Cr as load parameters, but the first estimated intake air amount Gcyl_vt The load parameter used for calculating the estimated flow rate Gin_vt is not limited to this, and any load parameter that represents the load of the engine 3 may be used. For example, the target cam phase Cain_cmd and the target compression ratio Cr_cmd may be used, and the valve lift Liftin and / or the target valve lift Liftin_cmd may be used.

  The embodiment is an example in which the maximum estimated intake air amount Gcyl_max is calculated according to the engine speed NE, the cam phase Cain, and the compression ratio Cr, but the maximum estimated intake air amount Gcyl_max depends on other parameters representing the engine load. May be calculated. For example, the maximum estimated intake air amount Gcyl_max may be calculated according to the engine speed NE and the target cam phase Cain_cmd and / or the target compression ratio Cr_cmd. The engine speed NE, the valve lift Liftin and the target valve lift Liftin_cmd You may calculate according to one of these.

  Furthermore, in the embodiment, the control apparatus 1 according to the present invention is configured such that the reliability of the first estimated intake air amount Gcyl_vt is the first when the air flow rate Gin is small, that is, when the load is low, because the intake passage is configured to have a large diameter. 2 is an example applied to the internal combustion engine 3 where the estimated intake air amount Gcyl_afm exceeds the estimated intake air amount Gcyl_afm and the reliability of the second estimated intake air amount Gcyl_afm exceeds the first estimated intake air amount Gcyl_vt. The present invention is not limited to this, and the present invention is also applicable to an engine having a load range in which the reliability of both is reversed between the first and second estimated intake air amounts Gcyl_vt and Gcyl_afm. For example, in the low load range, the reliability of the second estimated intake air amount Gcyl_afm exceeds the first estimated intake air amount Gcyl_vt, and in the high load region, intake pulsation occurs or the intake air flow velocity becomes too high. The first estimated intake air amount Gcyl_vt may be applied to an internal combustion engine in which the reliability exceeds the second estimated intake air amount Gcyl_afm. In that case, the multiplication term of Gcyl_afm in equation (4) may be set to (1-Kg), and the multiplication term of Gcyl_vt may be set to Kg.

  The embodiment is an example in which the basic fuel injection amount Tcyl_bs is calculated as the product Kgt · Gcyl of the conversion coefficient and the calculated intake air amount. The table is searched for the basic fuel injection amount Tcyl_bs according to the calculated intake air amount Gcyl. You may comprise so that it may calculate by. In that case, a table preset for each fuel injection valve 10 may be used.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 ECU (Operating state parameter detection means, load parameter detection means, 1st failure determination means, 2nd failure determination means, drive means, intake air amount calculation means, engine speed detection means, maximum intake air amount calculation means Ignition timing determination means, failure target speed setting means)
3 Internal combustion engine 3a Cylinder 3d Crankshaft 4 Intake valve 5 Intake camshaft 12a Intake passage 20 Crank angle sensor (load parameter detection means, engine speed detection means)
22 Air flow sensor (Air flow detection means)
25 Rotation angle sensor (operation state parameter detection means, load parameter detection means)
26 Cam angle sensor (operation state parameter detection means, load parameter detection means)
27 Control angle sensor (operation state parameter detection means, load parameter detection means)
50 Variable valve lift mechanism (variable intake mechanism)
70 Variable cam phase mechanism (variable intake mechanism)
80 Variable compression ratio mechanism (variable intake mechanism)
120 ignition timing controller (ignition timing determining means)
121 Maximum estimated intake air amount calculation unit (maximum intake air amount calculation means)
NE Engine speed (load parameter)
NE_fs Failure target rotation speed
Gin Air flow rate Gcyl_vt First estimated intake air amount Gcyl_afm Second estimated intake air amount Gcyl Calculated intake air amount (intake air amount)
Gcyl_fs Fault value (predetermined value)
Gcyl_max Maximum estimated intake air amount (maximum intake air amount)
Kgcyl normalized intake volume (ratio)
TOUT Fuel injection amount (fuel amount)
Iglog ignition timing Liftin valve lift (operating state parameters, load parameters)
Cain cam phase (operating state parameters, load parameters)
Cr compression ratio (operating condition parameters, load parameters)

Claims (6)

An intake air amount calculating means for calculating an intake air amount sucked into a cylinder of the internal combustion engine;
Engine speed detecting means for detecting the engine speed of the internal combustion engine;
A maximum intake air amount calculating means for calculating a maximum intake air amount that can be sucked into the cylinder at the engine speed according to the engine speed;
Ignition timing determining means for determining the ignition timing of the internal combustion engine according to the ratio of one of the intake air amount and the maximum intake air amount to the other and the engine speed;
A control device for an internal combustion engine, comprising: The internal combustion engine includes a variable intake mechanism that freely changes the intake air amount,
An operation state parameter detecting means for detecting an operation state parameter representing an operation state of the variable intake mechanism;
Air flow rate detection means for detecting the flow rate of air flowing in the intake passage of the internal combustion engine;
Load parameter detecting means for detecting a load parameter representing a load of the internal combustion engine;
Further comprising
The intake air amount calculation means calculates the intake air amount according to the operation state parameter when the load parameter is in a predetermined first range, and the load parameter is different from the predetermined first range. 2. The control device for an internal combustion engine according to claim 1, wherein when it is within a predetermined second range, calculation is performed according to a flow rate of the air. The predetermined first range and the predetermined second range are set not to overlap each other,
The intake air amount calculation means calculates the intake air amount according to the operating condition parameter and the air flow rate when the load parameter is between the predetermined first range and the predetermined second range. The control apparatus for an internal combustion engine according to claim 2. Further comprising first failure determination means for determining whether or not the air flow rate detection means has failed,
The intake air amount calculation means uses the intake air amount as the operation state parameter when the first failure determination means determines that the air flow rate detection means is out of order, regardless of the value of the load parameter. 4. The control apparatus for an internal combustion engine according to claim 2, wherein the calculation is performed accordingly. Second failure determination means for determining whether or not the variable intake mechanism has failed;
Drive means for driving the variable intake mechanism so that the intake air amount becomes a predetermined value when it is determined by the second failure determination means that the variable intake mechanism has failed;
When it is determined by the second failure determination means that the variable intake mechanism has failed, a failure target rotational speed setting means for setting a failure target rotational speed that is a target of the engine rotational speed;
Further comprising
The ignition timing determining means has a predetermined feedback control algorithm so that when the second failure determining means determines that the variable intake mechanism has failed, the engine rotational speed becomes the target rotational speed at failure. The control apparatus for an internal combustion engine according to any one of claims 2 to 4, wherein the ignition timing is determined by:   The variable intake mechanism includes a variable cam phase mechanism that changes a phase of an intake camshaft of the internal combustion engine with respect to a crankshaft, a variable valve lift mechanism that changes a lift of an intake valve of the internal combustion engine, and a compression ratio of the internal combustion engine. 6. The control apparatus for an internal combustion engine according to claim 2, further comprising at least one variable compression ratio mechanism to be changed.

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