JP2007009835A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of surely suppressing vibration at a time of idling operation of the internal combustion engine including multiple cylinders. <P>SOLUTION: Crank rotation speed is detected for each cylinder when each cylinder goes into expansion stroke. Average value of continuous eight engine rotation speeds at a time of expansion stroke of each cylinder going into expansion stroke is calculated. The calculated average value and crank rotation speed at a time of expansion stroke of each cylinder are compared, ignition timing of a spark plug 31 of a cylinder of which crank rotation speed at a time of expansion stroke is below the average speed is advanced and ignition timing of the spark plug 31 of the cylinder of which crank rotation speed at a time of expansion stroke is above the average speed is retarded. When ignition timing reaches MBT and crank rotation speed at a time of expansion stroke i of the cylinder is below the average speed, air fuel ratio of the cylinder is shifted to rich side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine (engine) mounted on an automobile or the like. In particular, the present invention relates to an improvement in control operation for suppressing vibration during an idling operation of an internal combustion engine having a plurality of cylinders.

  Conventionally, when idling (hereinafter simply referred to as idling) operation of a multi-cylinder engine mounted on an automobile or the like, there is a high possibility that variation occurs in the combustion state during the expansion stroke of each cylinder. It is said that this variation in the combustion state is caused by manufacturing variations of parts constituting the engine, deterioration with time, and the like, and cannot generally be avoided. If this variation in the combustion state occurs, torque fluctuation will be caused and the idling speed will become unstable, resulting in large vibrations in the engine.

  For example, the following Patent Document 1 and Patent Document 2 have been proposed as techniques for suppressing torque fluctuations during idle operation.

  In Patent Document 1, during idle operation, the amount of change in angular velocity during the expansion stroke is calculated for each cylinder, and based on these amounts of change, the ignition timing and fuel are set so that the difference in amount of change between the cylinders becomes zero. It is disclosed that the injection amount is corrected. Specifically, in a four-cylinder engine, the difference between the time required for the cylinder in the expansion stroke to rotate by a predetermined crank angle and the time required for the cylinder in the expansion stroke 180 ° before that crank angle to rotate by the predetermined crank angle. In other words, these expansion strokes balance the angular velocities between adjacent cylinders. For example, the ignition timing and the fuel injection amount are corrected so that the angular velocities of the first and second cylinders are balanced, and the ignition is performed so that the angular velocities of the third and fourth cylinders are balanced. The timing and fuel injection amount are corrected.

On the other hand, Patent Document 2 calculates the indicated mean effective pressure for each cylinder individually, and controls the ignition timing and the fuel injection amount so as to reduce the variation in the standard deviation of the indicated mean effective pressure of each cylinder. Is disclosed.
JP-A-2-64252 JP-A-8-319866

  However, all of the above-mentioned patent documents all perform feedback control of the ignition timing and the fuel injection amount based on the immediately preceding rotational fluctuation state, so that the immediately preceding rotational fluctuation state is suddenly caused by misfire or poor combustion. In the case of a large change, the ignition timing and the fuel injection amount are corrected with the feedback control amount that is greatly affected by the change. For this reason, there is a possibility of correcting the ignition timing and the fuel injection amount in the direction opposite to the direction that should be controlled. For example, in the case of the above-mentioned patent document 1, when the combustion failure occurs in the third cylinder and the angular velocity becomes extremely low, the fourth cylinder that reaches the expansion stroke thereafter balances with the angular velocity of the third cylinder. That is, in other words, the ignition timing is delayed so as to lower the angular velocity (retarding control), the fuel injection amount reduction control is performed, etc., the engine rotational speed is lowered, and the idle rotational speed is further reduced. There is a possibility that the vibration of the engine increases as the engine becomes stable.

The above-mentioned Patent Document 1 also discloses that the fuel injection amount for each cylinder is corrected so that the former approaches the latter by comparing the engine rotation speed of each cylinder with the average engine rotation speed of all cylinders. . However, also in this case, if the rotational fluctuation state suddenly changes greatly in any of the cylinders, the ignition timing and the fuel injection amount are corrected with the feedback control amount that has a large effect.

  For example, in the case of a four-cylinder engine, the average value of the engine rotation speed during the expansion stroke of each cylinder that has just reached four consecutive expansion strokes, and the cylinder (cylinder to be controlled) that is currently undergoing the expansion stroke The engine rotation speed at the previous expansion stroke is compared, and the fuel injection amount is corrected so that the engine rotation speed of the cylinder that reaches this expansion stroke approaches the average value.

  However, as shown in FIG. 4 (the vertical axis is the engine rotation speed during the expansion stroke, and the horizontal axis is the order of the cylinders in the expansion stroke), a sudden combustion failure occurred in the third cylinder (# 3 in the figure). In this case (timing D in FIG. 4), the fuel injection amount correction operation is performed so that the average value calculated thereafter becomes extremely low, and the engine rotation speed of the cylinder that reaches the current expansion stroke also becomes extremely low. It will be broken. Specifically, in the fuel injection amount correction control (control at timing E in the figure) for the fourth cylinder (# 4 in the figure) after the sudden combustion failure in the third cylinder has occurred, The average value of the engine speed during the four expansion strokes (timing A to D in the figure) of the immediately preceding No. 4 to No. 3 cylinders is used as the target of the engine speed during the current No. 4 cylinder expansion stroke. The target value of the engine speed is set lower than the originally required speed because the average value is low due to the sudden combustion failure in the third cylinder. Will be. That is, a sufficient fuel injection amount cannot be obtained, and the engine speed during the expansion stroke of the fourth cylinder is lowered. Such a situation is a fuel injection amount correction control for the first cylinder (# 1 in the figure) thereafter (control at timing F in the figure, and the average value of the engine speed at timings B to E in the figure is determined). Target control) and correction control of the fuel injection amount for the second cylinder (# 2 in the figure) (control at timing G in the figure, and target the average value of the engine speed at timings C to F in the figure) And control for correcting the fuel injection amount for the third cylinder (# 3 in the figure) (control at timing H in the figure, with the average value of engine rotation speeds at timings D to G in the figure as the target) This also occurs in the control), and a situation occurs in which the target value of the engine speed gradually decreases. Then, the fuel injection amount correction control for the fourth cylinder (# 4 in the figure) is performed (control at timing I in the figure, and the control is aimed at the average value of the engine speed at timings E to H in the figure). ) Does not use the engine speed data (data at timing D in the figure) during the expansion stroke of the third cylinder, which has suddenly failed, in calculating the average value. The target value of the engine speed during the expansion stroke of the fourth cylinder is suddenly set to be high, and a large torque fluctuation is caused at this timing. become.

  The present invention has been made in view of this point, and an object thereof is to propose a control device for an internal combustion engine that can reliably suppress vibration during idling operation of an internal combustion engine having a plurality of cylinders. There is.

The solving means of the present invention taken to achieve the above object is an internal combustion engine equipped with an ignition timing control means for controlling the ignition timing of a spark plug provided in each cylinder of an internal combustion engine having a plurality of cylinders. The control device is assumed. The control device for the internal combustion engine is provided with a rotation speed detection means, an average speed calculation means, and an ignition timing correction means. The rotation speed detection means detects the crank rotation speed in a predetermined crank angle range including the expansion stroke of each cylinder for each expansion stroke during the idling operation of the internal combustion engine. The average speed calculating means receives the output of the rotational speed detecting means and calculates the average speed of the crank rotational speed detected continuously with the number of times exceeding the number of cylinders possessed by the internal combustion engine. The ignition timing correction means receives the outputs of the rotation speed detection means and the average speed calculation means, and the crank rotation speed during the expansion stroke detected by the rotation speed detection means is lower than the average speed calculated by the average speed calculation means. For the cylinder, while the ignition timing of the spark plug is advanced, the cylinder rotational speed detected during the expansion stroke detected by the rotational speed detecting means exceeds the average speed calculated by the average speed calculating means. The ignition timing of the ignition plug by the ignition timing control means is corrected so as to retard the ignition timing of the ignition plug.

  Due to this specific matter, at the time of idling operation of the internal combustion engine, first, the rotational speed detecting means detects the crank rotational speed in a predetermined crank angle range including the expansion stroke of each cylinder for each expansion stroke of each cylinder. For example, the time during which the crankshaft rotates in an angle range of 90 ° crank angle before and after the piston of each cylinder reaches top dead center is detected, and the crank rotation speed in this crank angle range is detected. That is, the “predetermined crank angle range including the expansion stroke of each cylinder” means a crank angle including a part of the expansion stroke of each cylinder (in the above case, a range rotated from the compression top dead center to a crank angle of 45 °). Say range. Then, the average speed calculating means calculates the average speed of the crank rotational speeds detected continuously in the number of crank rotational speeds thus detected exceeding the number of cylinders of the internal combustion engine. For example, in the case of a four-cylinder internal combustion engine, the average speed is calculated with respect to eight consecutive crank rotation speeds detected. Then, for each cylinder, the crank rotational speed during the expansion stroke detected by the rotational speed detecting means is compared with the average speed calculated by the average speed calculating means. Based on the comparison result, the ignition timing of the spark plug is advanced for the cylinder whose crank rotation speed during the expansion stroke is lower than the average speed. As a result, the torque when the cylinder performs the expansion stroke increases, and approaches the torque when the other cylinder performs the expansion stroke. On the other hand, the ignition timing of the spark plug is retarded for the cylinder in which the crank rotation speed during the expansion stroke exceeds the average speed. As a result, the torque when the cylinder performs the expansion stroke decreases, and approaches the torque when the other cylinder performs the expansion stroke. By controlling the ignition timing as described above, the torques when the cylinders perform the expansion stroke can be brought closer to each other, and vibration during idling can be reliably suppressed as the torque stabilizes. In particular, according to the present invention, since the average speed of the crank rotational speed continuously detected with the number of times exceeding the number of cylinders possessed by the internal combustion engine is compared with the crank rotational speed at the expansion stroke of each cylinder, Even if the rotational fluctuation state suddenly changes greatly due to combustion failure or the like, it is not greatly affected, the control amount of the ignition timing can be appropriately obtained, and the vibration suppression effect is reliably obtained be able to.

  As another solution of the present invention taken in order to achieve the above object, it is possible to correct the air-fuel ratio control amount instead of correcting the ignition timing. The configuration in this case is as follows. First, a control device for an internal combustion engine provided with an air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder of the internal combustion engine having a plurality of cylinders is assumed. The control device for the internal combustion engine is provided with a rotational speed detection means, an average speed calculation means, and an air-fuel ratio correction means. The rotation speed detection means detects the crank rotation speed in a predetermined crank angle range including the expansion stroke of each cylinder for each expansion stroke during the idling operation of the internal combustion engine. The average speed calculating means receives the output of the rotational speed detecting means and calculates the average speed of the crank rotational speed detected continuously with the number of times exceeding the number of cylinders possessed by the internal combustion engine. The air-fuel ratio correcting means receives the outputs of the rotational speed detecting means and the average speed calculating means, and the crank rotational speed during the expansion stroke detected by the rotational speed detecting means is below the average speed calculated by the average speed calculating means. For the cylinder, the air-fuel ratio is shifted to the rich side, while for the cylinder in which the crank rotation speed during the expansion stroke detected by the rotation speed detection means exceeds the average speed calculated by the average speed calculation means, the cylinder is empty. The air-fuel ratio control amount by the air-fuel ratio control means is corrected so that the fuel ratio is shifted to the lean side.

According to this specific matter, for each cylinder, the crank rotational speed detected during the expansion stroke detected by the rotational speed detecting means is compared with the average speed calculated by the average speed calculating means, For cylinders whose crank rotational speed is below the average speed, the air-fuel ratio is shifted to the rich side. Specifically, the fuel injection amount from the injector is increased. As a result, the torque when the cylinder performs the expansion stroke increases, and approaches the torque when the other cylinder performs the expansion stroke. On the other hand, the air-fuel ratio is shifted to the lean side for the cylinder whose crank rotation speed during the expansion stroke exceeds the average speed. Specifically, the fuel injection amount from the injector is reduced. As a result, the torque when the cylinder performs the expansion stroke decreases, and approaches the torque when the other cylinder performs the expansion stroke. By controlling the air-fuel ratio as described above, the torques when the cylinders perform the expansion stroke can be brought closer to each other, and vibration during idling can be reliably suppressed as the torque stabilizes. And also in the present invention, since the average speed of the crank rotational speed continuously detected with the number of times exceeding the number of cylinders possessed by the internal combustion engine is compared with the crank rotational speed at the expansion stroke of each cylinder, Even if the rotational fluctuation state suddenly changes greatly due to misfire or combustion failure, the control amount of the air-fuel ratio can be appropriately obtained without being greatly affected, and the vibration suppression effect is ensured. Obtainable.

  Furthermore, as another solution of the present invention taken to achieve the above object, it is also possible to perform both the correction of the ignition timing and the correction of the air-fuel ratio control amount. The configuration in this case is as follows. First, an internal combustion engine comprising ignition timing control means for controlling the ignition timing of spark plugs provided in each cylinder of an internal combustion engine having a plurality of cylinders, and air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder It is assumed that the control device. The control device for the internal combustion engine is provided with a rotation speed detection means, an average speed calculation means, an ignition timing correction means, and an air-fuel ratio correction means. The rotation speed detection means detects the crank rotation speed in a predetermined crank angle range including the expansion stroke of each cylinder for each expansion stroke during the idling operation of the internal combustion engine. The average speed calculating means receives the output of the rotational speed detecting means and calculates the average speed of the crank rotational speed detected continuously with the number of times exceeding the number of cylinders possessed by the internal combustion engine. The ignition timing correction means receives the outputs of the rotation speed detection means and the average speed calculation means, and the crank rotation speed during the expansion stroke detected by the rotation speed detection means is lower than the average speed calculated by the average speed calculation means. For the cylinder, while the ignition timing of the spark plug is advanced, the cylinder rotational speed detected during the expansion stroke detected by the rotational speed detecting means exceeds the average speed calculated by the average speed calculating means. The ignition timing of the ignition plug by the ignition timing control means is corrected so as to retard the ignition timing of the ignition plug. The air-fuel ratio correcting means corrects the ignition timing of the spark plug by the ignition timing correcting means, and the crank speed during the expansion stroke of the cylinder whose ignition timing has reached MBT is still calculated by the average speed calculating means. If the air-fuel ratio is less than, the air-fuel ratio control amount by the air-fuel ratio control means is corrected so that the air-fuel ratio is shifted to the rich side for this cylinder.

According to this specific matter, first, as in the case described above, for each cylinder, the crank rotational speed during the expansion stroke detected by the rotational speed detecting means, and the average speed calculated by the average speed calculating means, Based on the comparison result, the ignition timing of the spark plug is advanced or retarded to suppress the vibration accompanying the stabilization of the torque. As a result of correcting the ignition timing, when there is a cylinder whose ignition timing has reached MBT, the crank speed during the expansion stroke of the cylinder is still the average speed calculated by the average speed calculating means. It is determined whether or not the air-fuel ratio is below, and if it is below the air-fuel ratio control amount, the air-fuel ratio control amount is corrected so that the air-fuel ratio is shifted to the rich side. That is, although the ignition timing has reached MBT, a control operation for further improving the torque by controlling the air-fuel ratio is performed on the cylinder that still has a lower torque than the other cylinders. The cylinder is brought close to the torque when the expansion stroke is performed. That is, the torque is stabilized by the synergistic effect of both the ignition timing control and the air-fuel ratio control to suppress vibration. In addition, since the ignition timing control is prioritized over the air-fuel ratio control, it is possible to ensure high control responsiveness and to avoid vibration deterioration while avoiding deterioration of the fuel consumption rate and drivability as much as possible. Suppression can be achieved.

  In addition, during idling operation of the internal combustion engine, instead of detecting the crank rotation speed for each expansion stroke of each cylinder, it is also possible to detect the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke of each cylinder. It is. The configuration will be described below.

  First, a control device for an internal combustion engine provided with an ignition timing control means for controlling the ignition timing of a spark plug provided in each cylinder of the internal combustion engine having a plurality of cylinders is assumed. The control device for the internal combustion engine is provided with in-cylinder pressure detecting means, average value calculating means, and ignition timing correcting means. The in-cylinder pressure detecting means detects the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke during the idling operation of the internal combustion engine. The average value calculating means receives the output of the in-cylinder pressure detecting means, and calculates the average value of the in-cylinder pressure detected continuously with the number of times exceeding the number of cylinders of the internal combustion engine. The ignition timing correction means receives the outputs of the in-cylinder pressure detecting means and the average value calculating means, and the average value in which the in-cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means is calculated by the average value calculating means. For cylinders lower than, the ignition timing of the spark plug is advanced, while the cylinder pressure during the expansion stroke detected by the cylinder pressure detection means exceeds the average value calculated by the average value calculation means. On the other hand, the ignition timing of the ignition plug by the ignition timing control means is corrected so as to retard the ignition timing of the ignition plug. The in-cylinder pressure value detected by the in-cylinder pressure detecting means includes the maximum pressure value during the expansion stroke and the illustrated average effective pressure value.

  Further, other means for solving the problem in the case where the in-cylinder pressure during the expansion stroke of each cylinder is detected for each expansion stroke of each cylinder can be exemplified as follows. First, a control apparatus for an internal combustion engine provided with air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder of the internal combustion engine having a plurality of cylinders is assumed. The control device for the internal combustion engine is provided with in-cylinder pressure detecting means, average value calculating means, and air-fuel ratio correcting means. The in-cylinder pressure detecting means detects the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke during the idling operation of the internal combustion engine. The average value calculating means receives the output of the in-cylinder pressure detecting means, and calculates the average value of the in-cylinder pressure detected continuously with the number of times exceeding the number of cylinders of the internal combustion engine. The air-fuel ratio correcting means receives the outputs of the in-cylinder pressure detecting means and the average value calculating means, and the in-cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means is an average value calculated by the average value calculating means. For cylinders that are less than, the air-fuel ratio is shifted to the rich side, while the cylinder pressure during the expansion stroke detected by the cylinder pressure detection means exceeds the average value calculated by the average value calculation means. Thus, the air-fuel ratio control amount by the air-fuel ratio control means is corrected so that the air-fuel ratio is shifted to the lean side.

Furthermore, when the in-cylinder pressure during the expansion stroke of each cylinder is detected for each expansion stroke of each cylinder, both the correction of the ignition timing and the correction of the air-fuel ratio control amount may be performed. The configuration in this case is as follows. First, an internal combustion engine comprising ignition timing control means for controlling the ignition timing of spark plugs provided in each cylinder of an internal combustion engine having a plurality of cylinders, and air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder It is assumed that the control device. The control device for the internal combustion engine is provided with in-cylinder pressure detection means, average value calculation means, ignition timing correction means, and air-fuel ratio correction means. The in-cylinder pressure detecting means detects the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke during the idling operation of the internal combustion engine. The average value calculating means receives the output of the in-cylinder pressure detecting means, and calculates the average value of the in-cylinder pressure detected continuously with the number of times exceeding the number of cylinders of the internal combustion engine. The ignition timing correction means receives the outputs of the in-cylinder pressure detecting means and the average value calculating means, and the average value in which the in-cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means is calculated by the average value calculating means. For cylinders lower than, the ignition timing of the spark plug is advanced, while the cylinder pressure during the expansion stroke detected by the cylinder pressure detection means exceeds the average value calculated by the average value calculation means. On the other hand, the ignition timing of the ignition plug by the ignition timing control means is corrected so as to retard the ignition timing of the ignition plug. The air-fuel ratio correction means calculates the average value of the in-cylinder pressure during the expansion stroke of the cylinder when the ignition timing of the spark plug is corrected by the ignition timing correction means and the ignition timing reaches MBT. When the average value calculated by the means is below, the air-fuel ratio control amount by the air-fuel ratio control means is corrected so that the air-fuel ratio is shifted to the rich side for this cylinder.

  As described above, the in-cylinder pressure during the expansion stroke of each cylinder is detected for each expansion stroke of each cylinder, and the detected in-cylinder pressure and the number of cylinders possessed by the internal combustion engine are determined for each cylinder. By comparing the average value of the in-cylinder pressure continuously detected with the number of times exceeded, and correcting the ignition timing of the spark plug and the control amount of the air-fuel ratio based on the comparison results, the torque of each cylinder can be stabilized. As a result, vibration during idling can be reliably suppressed.

  Each of the solutions described above recognizes the difference between the average combustion state of each cylinder and the combustion state of each cylinder when detecting variations in the combustion state of each cylinder during idle operation. In addition, there is a common technical feature in that the combustion state of each cylinder is controlled to approach the average combustion state.

  In addition to the above solutions, the following configuration can also be adopted for controlling the air / fuel ratio by the air / fuel ratio correcting means. In other words, when the fuel consumption rate deteriorates to a predetermined amount or more, or when the exhaust emission deteriorates to a predetermined amount or more, the air-fuel ratio correction unit maintains the ratio between the air-fuel ratios of the respective cylinders while maintaining the ratio between the air-fuel ratios of the cylinders. The air-fuel ratio control amount by the air-fuel ratio control means is corrected so as to shift the air-fuel ratio to the lean side. According to this, it is possible to suppress the deterioration of the fuel consumption rate and the exhaust emission while maintaining the effect of suppressing the vibration during the idling operation.

  In the present invention, the average speed of the crank rotational speed continuously detected with the number of times exceeding the number of cylinders possessed by the internal combustion engine is compared with the crank rotational speed at the expansion stroke of each cylinder, or the internal combustion engine has By comparing the average value of the in-cylinder pressure continuously detected with the number of times exceeding the number of cylinders, and the in-cylinder pressure value during the expansion stroke of each cylinder, the ignition timing control and air-fuel ratio control are performed. ing. For this reason, even when the rotational fluctuation state suddenly changes greatly due to misfire or combustion failure, it is not greatly affected, and torque fluctuation during idling can be suppressed and vibration suppression effect can be achieved. You can definitely get it.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to an automobile four-cylinder gasoline engine will be described.

-Engine configuration description-
First, a schematic configuration of an engine (internal combustion engine) and its peripheral devices according to this embodiment will be described with reference to FIG. As shown in FIG. 1, the engine 1 according to the present embodiment includes a cylinder block 2 having cylinder bores 21 for four cylinders (only one cylinder is shown in FIG. 1), and a cylinder head 3. Each cylinder bore 21 is provided with a piston 4 that is reciprocally movable. The piston 4 is connected to a crankshaft 5 that is an output shaft of the engine 1 via a connecting rod (connecting rod) 41. A combustion chamber 11 is defined by a space surrounded by the piston 4 and the cylinder head 3 inside the cylinder bore 21.

A spark plug (ignition plug) 31 is attached to the cylinder head 3 corresponding to each combustion chamber 11. The spark plug 31 performs an ignition operation on the air-fuel mixture in accordance with the application timing of the high voltage output from the igniter 34.

  Further, the cylinder head 3 is provided with an intake port 32 and an exhaust port 33 communicating with each combustion chamber 11, and the intake port 32 and the exhaust port 33 constitute an intake pipe 6 and an exhaust passage that constitute an intake passage. Each exhaust pipe 7 is connected. An intake valve 61 and an exhaust valve 71 are provided at each opening end of the intake port 32 and the exhaust port 33 that communicate with the combustion chamber 11. The intake valve 61 and the exhaust valve 71 are opened and closed by an intake camshaft 62 and an exhaust camshaft 72 that are respectively rotated by the power of the crankshaft 5. The power of the crankshaft 5 is transmitted to the intake camshaft 62 and the exhaust camshaft 72 via the timing belt 51 and the timing pulleys 63 and 73.

  In the vicinity of the intake port 32, a fuel injection valve (injector) 64 is provided corresponding to each cylinder. Each fuel injection valve 64 is supplied with fuel of a predetermined pressure via a fuel supply system (not shown).

  On the other hand, an air cleaner 65 for purifying the intake air is provided at the upstream end portion of the intake pipe 6, and a throttle that is driven to open and close in accordance with the operation of an accelerator pedal (not shown) is provided downstream of the air cleaner 65. A valve 66 is provided. The amount of intake air introduced into the intake pipe 6 is adjusted according to the opening of the throttle valve 66. A surge tank 67 is provided on the downstream side of the throttle valve 66 to suppress pulsation of the intake air flow.

  The intake pipe 6 is provided with a bypass passage 68 that bypasses the throttle valve 66 and communicates the upstream side and the downstream side of the throttle valve 66. In the middle of the bypass passage 68, a linear solenoid type idle speed control valve (hereinafter referred to as "ISCV") 69 is provided as a bypass air amount adjustment valve for adjusting the flow rate of air flowing through the bypass passage 68. The ISCV 69 is configured by an electromagnetic valve that adjusts a passage area through which a valve (not shown) is displaced in accordance with the duty ratio of a duty drive signal output to a solenoid coil (not shown). Further, the ISCV 69 operates during the idling operation of the engine 1 in which the throttle valve 66 is fully closed, and is controlled based on a predetermined duty drive signal, that is, the ISCV control is performed. The flowing air amount (bypass air amount) is adjusted, and the intake air amount taken into the combustion chamber 11 is adjusted.

  When the operation of the engine 1 is started, the intake air is introduced into the intake pipe 6 and fuel is injected from the fuel injection valve 64, whereby the intake air and the fuel are mixed to become an air-fuel mixture. . In the intake stroke of the engine 1, the intake port 32 is opened by the intake valve 61, whereby the air-fuel mixture is taken into the combustion chamber 11 through the intake port 32. The air-fuel mixture taken into the combustion chamber 11 is compressed in the compression stroke, and then ignited by the spark plug 31. The air-fuel mixture explodes and burns, and driving force is applied to the crankshaft 5 (expansion stroke). . The exhaust gas after combustion is discharged to the exhaust pipe 7 by opening the exhaust port 33 by the exhaust valve 71 (exhaust stroke), further purified through the catalytic converter 74, and then released to the outside.

  The engine 1 according to the present embodiment is provided with various sensors as described below for detecting the operating state.

A crank angle sensor 81 for detecting the rotation angle (crank angle CA) and the rotation speed (engine rotation speed NE) is disposed in the vicinity of the crankshaft 5. The crank angle sensor 81 outputs a pulse signal every predetermined crank angle (for example, 30 °). As an example of the crank angle detection method by the crank angle sensor 81, external teeth are formed at intervals of 30 ° on the outer peripheral surface of a rotor (NE rotor) (not shown) that is integrally rotated with the crankshaft 5, and The crank angle sensor 81 made of an electromagnetic pickup is disposed so as to face. When the external teeth pass in the vicinity of the crank angle sensor 81 as the crankshaft 5 rotates, the crank angle sensor 81 generates an output pulse. In addition, as this rotor, the thing in which the external tooth formed in an outer peripheral surface was formed every 10 degrees may be applied.

  A cam angle sensor 82 is disposed in the vicinity of the intake camshaft 62. The cam angle sensor 82 is normally used as a cylinder discrimination sensor, and outputs a pulse signal corresponding to, for example, the compression top dead center (TDC) of the first cylinder # 1. That is, the cam angle sensor 82 outputs a pulse signal for each rotation of the intake camshaft 62. As an example of the cam angle detection method by the cam angle sensor 82, an external tooth is formed at one place on the outer peripheral surface of the rotor integrated with the intake camshaft 62, and this external tooth is faced with an electromagnetic pickup. The cam angle sensor 82 is arranged, and when the external teeth pass near the cam angle sensor 82 as the intake cam shaft 62 rotates, the cam angle sensor 82 generates an output pulse. . Since this rotor rotates at half the rotational speed of the crankshaft 5, an output pulse is generated every time the crankshaft 5 rotates 720 °. In other words, an output pulse is generated each time a specific cylinder reaches the same stroke (for example, when the first cylinder # 1 reaches compression top dead center).

  The surge tank 67 is provided with a pressure sensor 83 for detecting the pressure in the intake pipe 6 (intake pipe pressure PM). The pressure sensor 83 outputs a signal corresponding to the pressure in the surge tank 65.

  A throttle sensor 84 for detecting the throttle opening is provided in the vicinity of the throttle valve 66. The throttle sensor 84 outputs a detection signal corresponding to the throttle opening. The throttle sensor 84 incorporates an idle switch (not shown) that is turned on only when the throttle valve 66 is in the fully closed position, and outputs an idle signal indicating the ON / OFF state of the switch. The throttle sensor 84 in the present embodiment functions as an idle determination means for determining whether or not the engine 1 is in an idle state.

  The above is the schematic configuration of the engine according to the present embodiment.

-Configuration and operation for idle speed control-
Next, a configuration and operation for idle speed control, which is a feature of the present embodiment, will be described.

  The engine 1 includes an ECU 9 configured with, for example, a microcomputer. The ECU 9 receives the output signals of the sensors 81 to 84, respectively. The ECU 9 calculates the crank angle CA, the engine speed NE, the current operating cylinder (for example, the cylinder that is currently in the expansion stroke), the intake pipe pressure PM, and the like based on these signals. It is determined whether or not the engine is in an idle state, and based on these, an idle speed control operation to be described later is executed.

The ECU 9 determines the reference ignition timing of the spark plug 31 in accordance with each received signal (which is determined by the basic control operation of the ignition timing control means referred to in the present invention and is based on a previously stored map. The ignition timing obtained by adding “correction advance angle” determined according to the coolant temperature detected by a water temperature sensor (not shown) to the “basic advance angle” or a reference from the fuel injection valve 64 Fuel injection amount ("basic injection amount" determined by the basic control operation of the air-fuel ratio control means in the present invention, which is determined by the intake air amount detected by an air flow meter (not shown), the engine speed, etc. In addition, a fuel injection amount obtained by adding a “correction injection amount” determined in accordance with the intake air temperature, the cooling water temperature, or the like is determined. In the idle speed control operation according to the present embodiment, correction is performed with a predetermined correction amount with respect to the reference ignition timing and the reference fuel injection amount respectively determined during the idle operation. Details will be described later.

  This idle speed control operation is performed by “rotation speed detection operation”, “average speed calculation operation”, “ignition timing correction operation”, and “air-fuel ratio correction operation”. Hereinafter, each operation will be described.

  “Rotational speed detection operation (operation of the rotational speed detection means in the present invention)” refers to the crank rotational speed in a predetermined crank angle range including the expansion stroke of each cylinder during the idling operation of the engine 1 for each expansion stroke. It has come to be detected. Specifically, 45 ° from the compression top dead center (TDC) when each cylinder reaches the expansion stroke to the advance side (crank rotation return side) and 45 ° to the retard side (crank rotation advance side). , The time required for the crankshaft 5 to rotate is detected in the crank angle range of 90 ° in total (detected by the crank angle sensor 81), and this is used as the crank rotation of the cylinder (cylinder in the expansion stroke). Detect as speed.

  The “average speed calculation operation (the operation of the average speed calculation means in the present invention)” is an expansion that is performed eight times with respect to the crank rotation speed during the expansion stroke of each cylinder detected by the “rotational speed detection operation” as described above. This is an operation for calculating the average value of the engine rotation speed during the expansion stroke of each cylinder that has reached the stroke. For example, in an engine that reaches the expansion stroke in order from the first cylinder # 1 to the fourth cylinder # 4, when the first cylinder # 1 is the control target, each of the expansion strokes that has just reached eight consecutive expansion strokes. The average value of the engine rotation speed during the expansion stroke of each cylinder (two expansion strokes from the first cylinder # 1 to the fourth cylinder # 4) is calculated.

  The “ignition timing correction operation (operation of the ignition timing correction means in the present invention)” is the average value calculated in the “average speed calculation operation” as described above and the crank rotational speed at the previous expansion stroke in each cylinder. The comparison is an operation of correcting the ignition timing of the spark plug 31 for each cylinder in accordance with the comparison result (correcting the reference ignition timing of the spark plug 31 described above). Specifically, for the cylinder whose crank rotation speed during the expansion stroke is lower than the average speed, the ignition timing of the spark plug 31 is advanced, while the crank rotation speed during the expansion stroke is higher than the average speed. On the other hand, the ignition timing of the spark plug 31 is retarded.

  The advance amount and retard amount of these ignition timings are changed by 1 degree at a crank angle in one control operation. Further, the advance amount or the retard amount may be changed according to the difference between the crank rotational speed during the expansion stroke of the cylinder to be controlled and the average speed. That is, when the crank rotational speed during the expansion stroke is lower than the average speed, the larger the difference is, the more the ignition timing is advanced, while the crank rotational speed during the expansion stroke is higher than the average speed. In this case, the control is such that the larger the difference is, the more the retard amount of the ignition timing is increased.

The “air-fuel ratio correction operation (operation of the air-fuel ratio correction means in the present invention)” controls the ignition timing of the spark plug 31 to the advance side by the “ignition timing correction operation”, and the ignition timing is MBT ( Minimum Spark Advance for Best
(Torque: optimal ignition timing), and if the crank rotational speed during the expansion stroke of the cylinder is still below the average speed, the air-fuel ratio is shifted to the rich side for this cylinder. The fuel injection amount from the fuel injection valve 64 is increased (correction is increased with respect to the reference fuel injection amount of the fuel injection valve 64 described above). As the shift amount of the air-fuel ratio to the rich side, the fuel injection amount may be increased by a predetermined amount in one control operation, or the crank rotational speed at the expansion stroke of the cylinder to be controlled and the above-mentioned The increase rate of the fuel injection amount may be changed according to the difference from the average speed. That is, when the crank rotational speed during the expansion stroke is lower than the average speed, the control is such that the increase rate of the fuel injection amount is set to be larger as the difference is larger.

  The MBT is set according to the engine speed, and is stored in advance in a memory in the ECU 9 as a map.

  The above is the operation executed by the idle speed control operation according to the present embodiment.

  Hereinafter, the control procedure of the idle speed control in the present embodiment will be described along the flowchart of FIG. First, after the engine 1 is started by performing an ignition ON operation (starting operation using an ignition key or pushing a start switch) in step ST1, the engine 1 receives a signal from the throttle sensor 84 in step ST2. It is determined whether or not is in an idle operation state. Moreover, you may make it determine whether it is an idle driving | running state by the signal from the crank angle sensor 81 and an accelerator opening sensor. That is, when the engine speed is equivalent to idle rotation and the accelerator opening is in the fully closed state, it is determined that the engine 1 is in the idle operation state.

  If the determination in step ST2 is NO, the engine 1 is not in an idle operation state, and thus this routine is terminated without executing this idle speed control. On the other hand, if the determination in step ST2 is YES, that is, if the engine 1 is in an idle operation state, the process proceeds to idle speed control after step ST3.

  In this step ST3, the crank rotation speed in the predetermined crank angle range including the expansion stroke of each cylinder (in the present embodiment, a total of 90 ° before and after TDC is 90 °) is detected for each expansion stroke of each cylinder. . Then, in step ST4, each cylinder that has undergone eight consecutive expansion strokes immediately before the cylinder to be controlled reaches the expansion stroke with respect to the crank rotational speed at the expansion stroke of each cylinder thus detected. The average value of the engine speed during the expansion stroke is calculated, and the process proceeds to step ST5.

  In step ST5, the average value calculated in step ST4 is compared with the crank rotation speed during the previous expansion stroke of the cylinder to be controlled. In step ST6, when the crank rotational speed of the cylinder to be controlled during the previous expansion stroke is lower than the average speed, the ignition timing of the spark plug 31 is advanced with respect to the cylinder. When the crank rotational speed of the cylinder to be controlled during the previous expansion stroke exceeds the average speed, the ignition timing of the spark plug 31 is retarded for the cylinder.

  After performing such advance / retard control of the ignition timing, it is determined in step ST7 whether or not there is a cylinder whose ignition timing has reached MBT. If there is no cylinder whose ignition timing has reached MBT, NO is determined in this step ST7, and the idling speed control is terminated. On the other hand, if there is a cylinder whose ignition timing has reached MBT, the determination in step ST7 is YES, and the process proceeds to step ST8.

In step ST8, the average value calculated in step ST4 is compared with the crank rotation speed during the expansion stroke of the cylinder that has reached MBT. And in step ST9,
If the crank rotational speed during the expansion stroke of the cylinder is still below the average speed, in step ST10, the fuel from the fuel injection valve 64 is shifted so that the air-fuel ratio is shifted to the rich side for that cylinder. Increase the injection amount.

After the above-described series of control operations is performed, the control operations of Step ST2 to Step ST10 are performed until the engine stop operation (IG OFF) is performed, and the idle speed control is always performed during the idle operation of the engine 1. Will be executed. The above is the idling speed control operation according to the present embodiment.

  Next, an example of the fluctuation state of the idle speed when the idle speed control operation according to the present embodiment is executed will be described.

  In FIG. 3, the vertical axis represents the engine speed during the expansion stroke, and the horizontal axis represents the order of the cylinders in the expansion stroke, and sudden combustion failure occurs in the third cylinder (# 3 in the figure) (FIG. 3). 3 shows the fluctuation state of the engine rotation speed during the expansion stroke of each cylinder at timing D).

  In this embodiment, the average value of the engine rotation speed at the time of the expansion stroke of each cylinder that has just reached the expansion stroke 8 times immediately before is calculated, and the idle rotation speed is controlled using this as the target value. In other words, in the correction control (control at timing E in the figure) for the fourth cylinder (# 4 in the figure) after the sudden combustion failure in the third cylinder, 2 of the fourth cylinder itself. The average value of the engine rotation speed from the previous expansion stroke (timing W in the figure) to the immediately preceding expansion stroke of the third cylinder (timing D in the figure) is used as the engine in the expansion stroke of the current fourth cylinder. It is set as the target value for the rotational speed. In this case, as can be seen from the case of the conventional example (see timing E in FIG. 4), the average value is significantly lowered due to the sudden combustion failure in the third cylinder. Rather, the target value of the engine rotational speed can be set in the vicinity of the originally required rotational speed. That is, the engine speed during the expansion stroke of the fourth cylinder does not decrease. Further, the idle after the subsequent correction control for the first cylinder (# 1 in the figure, which is control at timing F in the figure and is targeted at the average value of the engine speed at timings X to E in the figure). Similarly, in the rotational speed control, the target value of the engine rotational speed can be set in the vicinity of the originally required rotational speed, and the engine rotational speed during the expansion stroke of each cylinder does not decrease. As a result, the vibration of the engine 1 can be significantly suppressed.

  As described above, in the present embodiment, even when the rotational fluctuation state suddenly changes greatly due to misfire or combustion failure, it is not greatly affected, and the control amount of the ignition timing and the fuel injection A control amount of the amount can be appropriately obtained, and a vibration suppressing effect can be reliably obtained.

(First modification)
Next, a first modification of the present invention will be described. In the above-described embodiment, by detecting the crank rotational speed in a predetermined crank angle range including the expansion stroke of each cylinder for each expansion stroke of each cylinder, variation in each cylinder during idle operation (variation in combustion state) is achieved. I was trying to detect it. Instead, in this modification, each cylinder is provided with an in-cylinder pressure sensor, and the in-cylinder pressure sensor detects the maximum value of the in-cylinder pressure during the expansion stroke of each cylinder and the average effective pressure value shown in the figure. It is designed to detect every stroke. In the following description, a case where the maximum value of the in-cylinder pressure is detected by the in-cylinder pressure sensor will be described. The in-cylinder pressure sensor is generally disposed in the vicinity of the spark plug 31 in the cylinder head 3.

In this modification, instead of the “rotation speed detection operation” and the “average speed calculation operation” in the idle rotation speed control operation of the above-described embodiment, the “in-cylinder pressure detection operation” and the “average value calculation operation” are executed. become. Hereinafter, each operation will be described.

  In the “in-cylinder pressure detection operation (operation of the in-cylinder pressure detection means in the present invention)”, the in-cylinder pressure sensor detects the maximum value of the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke. .

  In the “average value calculation operation (operation of the average value calculation means in the present invention)”, the maximum value of the in-cylinder pressure during the expansion stroke of each cylinder detected by the “in-cylinder pressure detection operation” as described above is 8 The average value of the maximum values of the in-cylinder pressures during the expansion stroke of each cylinder that has reached the expansion strokes that are repeated twice is calculated. For example, in an engine that reaches the expansion stroke in order from the first cylinder # 1 to the fourth cylinder # 4, when the first cylinder # 1 is the control target, each of the expansion strokes that has just reached eight consecutive expansion strokes. The average value of the maximum value of the in-cylinder pressure during the expansion stroke of each cylinder (two expansion strokes from the first cylinder # 1 to the fourth cylinder # 4) is calculated.

  In the “ignition timing correction operation (operation of the ignition timing correction means in the present invention)”, as described above, the average value calculated in the “in-cylinder pressure detection operation” and the in-cylinder at the time of the expansion stroke immediately before each cylinder. The maximum value of the pressure is compared, and the ignition timing of the spark plug 31 is corrected for each cylinder according to the comparison result. Specifically, for the cylinder in which the maximum value of the in-cylinder pressure during the expansion stroke is below the average value, the ignition timing of the spark plug 31 is advanced, while the maximum value of the in-cylinder pressure during the expansion stroke is For cylinders exceeding the average value, the ignition timing of the spark plug 31 is retarded.

  In the “air-fuel ratio correcting operation (operation of the air-fuel ratio correcting means in the present invention)”, the ignition timing of the spark plug 31 is controlled to the advance side by the “ignition timing correcting operation”, and the ignition timing is When MBT is reached, if the maximum value of the in-cylinder pressure during the expansion stroke of the cylinder is still below the average value, fuel injection is performed so that the air-fuel ratio is shifted to the rich side for this cylinder. The amount of fuel injection from the valve 64 is increased. Other configurations and control operations of the engine 1 are the same as those of the above-described embodiment.

  As described above, even in this modification, as in the case of the above-described embodiment, even when the rotational fluctuation state suddenly changes greatly due to misfire or combustion failure, it is not greatly affected. The control amount of the ignition timing and the control amount of the fuel injection amount can be appropriately obtained, and the vibration suppressing effect can be reliably obtained.

(Second modification)
Next, a second modification of the present invention will be described. In the present modification, when the idle speed control is performed as in the above-described embodiment and the first modification, a control operation for avoiding deterioration of the fuel consumption rate and the exhaust emission is added.

  Specifically, the ratio between the air-fuel ratios of the cylinders when the fuel consumption rate deteriorates to a predetermined amount or more during the execution of the idle speed control or the exhaust emission deteriorates to a predetermined amount or more. The air-fuel ratio of all the cylinders is controlled to shift to the lean side while maintaining the above. For example, in the case where the ratio between the air-fuel ratios of the cylinders is # 1: # 2: # 3: # 4 = 1: 1.2: 1.2: 1 by the idle speed control. The fuel injection amount is reduced and the amount of air flowing through the bypass passage 68 (bypass air amount) (ISCV control) is adjusted so that the air-fuel ratio is shifted to the lean side while maintaining this ratio. It has become.

  According to this, since the idling speed of each cylinder will decrease substantially uniformly, the deterioration of the fuel consumption rate and the deterioration of the exhaust emission are suppressed while maintaining the vibration suppressing effect during the idling operation. Can be achieved.

  Specifically, as an operation for detecting that the fuel consumption rate has deteriorated beyond a predetermined amount, the fuel consumption rate is calculated based on the fuel injection amount from the fuel injection valve 64, a vehicle speed signal from a vehicle speed sensor (not shown), or the like. Then, it is performed by determining whether or not the calculated value is worse than a predetermined value (fuel consumption deterioration limit value).

  The operation for detecting that the exhaust emission has deteriorated by a predetermined amount or more is performed, for example, by determining whether or not the NMHC emission value of US FTP exceeds a predetermined value (emission deterioration limit value).

(Other embodiments)
In the above-described embodiments and modifications, the case where the present invention is applied to a four-cylinder gasoline engine for automobiles has been described. However, the present invention is not limited to this and can be applied to various engines.

  Further, in the above-described embodiment, the average value of the engine rotation speed during the expansion stroke of each cylinder that has reached eight consecutive expansion strokes in the “average speed calculation operation” is calculated. Further, in the first modified example, the average value of the maximum value of the in-cylinder pressure during the expansion stroke of each cylinder that has reached eight consecutive expansion strokes in the “average value calculation operation” is calculated. The present invention is not limited to this, and it is only necessary to calculate the average of data continuously detected by the number of times exceeding the number of cylinders that the engine 1 has. For example, the number of cylinders that the engine 1 has The average value of the engine rotation speed and the maximum value of the in-cylinder pressure of each cylinder that has reached an expansion stroke that is continuous (16 consecutive times, etc.) with an integer multiple (2, 3, 4, ... n times). The average value may be calculated.

  In the above-described embodiment and modification, both the “ignition timing correction operation” and the “air-fuel ratio correction operation” are performed. However, only one of these correction operations may be performed. That is, when only the “ignition timing correction operation” is performed, an ignition plug is used for a cylinder in which the crank rotational speed during the expansion stroke is lower than the average speed or a cylinder in which the in-cylinder pressure during the expansion stroke is lower than the average value. While the ignition timing of the ignition plug 31 is advanced, the ignition timing of the ignition plug 31 is set for a cylinder in which the crank rotational speed during the expansion stroke exceeds the average speed or a cylinder in which the in-cylinder pressure during the expansion stroke exceeds the average value. A vibration suppressing effect can be obtained only by retarding the angle. On the other hand, when only the “air-fuel ratio correction operation” is performed, fuel injection is performed for a cylinder whose crank rotation speed during the expansion stroke is lower than the average speed or for a cylinder whose cylinder pressure during the expansion stroke is lower than the average value. While the fuel injection amount from the valve 64 is increased, the fuel injection valve 64 is used for a cylinder in which the crank rotation speed during the expansion stroke exceeds the average speed or a cylinder in which the in-cylinder pressure during the expansion stroke exceeds the average value. The vibration suppressing effect can be obtained only by reducing the fuel injection amount from the above.

It is a figure which shows schematic structure of the engine which concerns on embodiment, and its peripheral device. It is a flowchart figure which shows the control procedure of idle speed control. It is a figure which shows an example of the fluctuation | variation state of an idle speed at the time of performing the idle speed control operation | movement which concerns on embodiment. It is a figure which shows an example of the fluctuation | variation state of an idle speed at the time of performing the idle speed control operation in a prior art example.

Explanation of symbols

1 engine (internal combustion engine)
2 Cylinder bore 31 Spark plug (ignition plug)
64 Fuel injection valve

Claims (7)

In an internal combustion engine control device comprising ignition timing control means for controlling the ignition timing of a spark plug provided in each cylinder of an internal combustion engine having a plurality of cylinders,
A rotation speed detecting means for detecting a crank rotation speed in a predetermined crank angle range including an expansion stroke of each cylinder for each expansion stroke of each cylinder during idling operation of the internal combustion engine;
Average speed calculation means for receiving the output of the rotation speed detection means and calculating the average speed of the crank rotation speed continuously detected at a number exceeding the number of cylinders of the internal combustion engine;
Ignition is performed for the cylinders that receive the outputs of the rotational speed detecting means and the average speed calculating means and whose crank rotational speed during the expansion stroke detected by the rotational speed detecting means is below the average speed calculated by the average speed calculating means. While the ignition timing of the plug is advanced, the ignition timing of the ignition plug is set for a cylinder in which the crank rotation speed during the expansion stroke detected by the rotation speed detection means exceeds the average speed calculated by the average speed calculation means. A control apparatus for an internal combustion engine, comprising: an ignition timing correcting means for correcting the ignition timing of the spark plug by the ignition timing control means so as to retard. In a control device for an internal combustion engine comprising air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder of an internal combustion engine having a plurality of cylinders,
A rotation speed detecting means for detecting a crank rotation speed in a predetermined crank angle range including an expansion stroke of each cylinder for each expansion stroke of each cylinder during idling operation of the internal combustion engine;
Average speed calculation means for receiving the output of the rotation speed detection means and calculating the average speed of the crank rotation speed continuously detected at a number exceeding the number of cylinders of the internal combustion engine;
Receiving outputs from the rotation speed detection means and the average speed calculation means, the cylinder rotation speed during the expansion stroke detected by the rotation speed detection means is empty for the cylinders below the average speed calculated by the average speed calculation means. While the fuel ratio is shifted to the rich side, the air-fuel ratio is shifted to the lean side for cylinders in which the crank rotational speed during the expansion stroke detected by the rotational speed detecting means exceeds the average speed calculated by the average speed calculating means. An internal combustion engine control apparatus comprising: an air-fuel ratio correction means for correcting an air-fuel ratio control amount by the air-fuel ratio control means. Control of internal combustion engine comprising ignition timing control means for controlling ignition timing of spark plugs provided in each cylinder of an internal combustion engine having a plurality of cylinders, and air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder In the device
A rotation speed detecting means for detecting a crank rotation speed in a predetermined crank angle range including an expansion stroke of each cylinder for each expansion stroke of each cylinder during idling operation of the internal combustion engine;
Average speed calculation means for receiving the output of the rotation speed detection means and calculating the average speed of the crank rotation speed continuously detected at a number exceeding the number of cylinders of the internal combustion engine;
Ignition is performed for the cylinders that receive the outputs of the rotational speed detecting means and the average speed calculating means and whose crank rotational speed during the expansion stroke detected by the rotational speed detecting means is below the average speed calculated by the average speed calculating means. While the ignition timing of the plug is advanced, the ignition timing of the ignition plug is set for a cylinder in which the crank rotation speed during the expansion stroke detected by the rotation speed detection means exceeds the average speed calculated by the average speed calculation means. Ignition timing correction means for correcting the ignition timing of the spark plug by the ignition timing control means so as to retard,
The ignition timing correction means corrects the ignition timing of the spark plug so that the ignition timing is MBT (Minimum Spark Advance for Best T).
orque: the optimum ignition timing), and if the crank rotational speed during the expansion stroke of the cylinder is still below the average speed calculated by the average speed calculating means, And an air-fuel ratio correction means for correcting an air-fuel ratio control amount by the air-fuel ratio control means so as to shift the air-fuel ratio to the rich side. In an internal combustion engine control device comprising ignition timing control means for controlling the ignition timing of a spark plug provided in each cylinder of an internal combustion engine having a plurality of cylinders,
In-cylinder pressure detecting means for detecting the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke during idling operation of the internal combustion engine;
An average value calculating means for receiving an output of the in-cylinder pressure detecting means and calculating an average value of the in-cylinder pressure continuously detected by the number of times exceeding the number of cylinders of the internal combustion engine;
With respect to the cylinder that receives the outputs of the in-cylinder pressure detecting means and the average value calculating means, and the cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means is below the average value calculated by the average value calculating means. While the ignition timing of the spark plug is advanced, the cylinder pressure at the expansion stroke detected by the cylinder pressure detecting means exceeds the average value calculated by the average value calculating means for the cylinder. A control apparatus for an internal combustion engine, comprising: ignition timing correction means for correcting the ignition timing of the spark plug by the ignition timing control means so as to retard the ignition timing. In a control device for an internal combustion engine comprising air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder of an internal combustion engine having a plurality of cylinders,
In-cylinder pressure detecting means for detecting the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke during idling operation of the internal combustion engine;
An average value calculating means for receiving an output of the in-cylinder pressure detecting means and calculating an average value of the in-cylinder pressure continuously detected by the number of times exceeding the number of cylinders of the internal combustion engine;
With respect to the cylinder that receives the outputs of the in-cylinder pressure detecting means and the average value calculating means, and the cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means is below the average value calculated by the average value calculating means. Shifts the air-fuel ratio to the rich side, while leaning the air-fuel ratio to the cylinder where the in-cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means exceeds the average value calculated by the average value calculating means. And an air-fuel ratio correction means for correcting the air-fuel ratio control amount by the air-fuel ratio control means so as to shift to the side. Control of internal combustion engine comprising ignition timing control means for controlling ignition timing of spark plugs provided in each cylinder of an internal combustion engine having a plurality of cylinders, and air-fuel ratio control means for individually controlling the air-fuel ratio of each cylinder In the device
In-cylinder pressure detecting means for detecting the in-cylinder pressure during the expansion stroke of each cylinder for each expansion stroke during idling operation of the internal combustion engine;
An average value calculating means for receiving an output of the in-cylinder pressure detecting means and calculating an average value of the in-cylinder pressure continuously detected by the number of times exceeding the number of cylinders of the internal combustion engine;
With respect to the cylinder that receives the outputs of the in-cylinder pressure detecting means and the average value calculating means, and the cylinder pressure during the expansion stroke detected by the in-cylinder pressure detecting means is below the average value calculated by the average value calculating means. While the ignition timing of the spark plug is advanced, the cylinder pressure at the expansion stroke detected by the cylinder pressure detecting means exceeds the average value calculated by the average value calculating means for the cylinder. Ignition timing correction means for correcting the ignition timing of the spark plug by the ignition timing control means so as to retard the ignition timing;
When there is a cylinder in which the ignition timing of the spark plug is corrected by the ignition timing correction means and the ignition timing reaches MBT (Minimum Spark Advance for Best Torque), the cylinder in the expansion stroke of the cylinder When the pressure is still below the average value calculated by the average value calculation means, the air-fuel ratio control amount by the air-fuel ratio control means is corrected so that the air-fuel ratio is shifted to the rich side for this cylinder. An internal combustion engine control device comprising air-fuel ratio correction means. In the control device for an internal combustion engine according to claim 2, 3, 5 or 6,
When the fuel consumption rate deteriorates to a predetermined amount or more, or when the exhaust emission deteriorates to a predetermined amount or more, the air-fuel ratio correction means maintains the ratio between the air-fuel ratios of the cylinders while maintaining the air-fuel ratio of all the cylinders. A control apparatus for an internal combustion engine, characterized in that the air-fuel ratio control amount by the air-fuel ratio control means is corrected so as to shift the fuel ratio to the lean side.

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