JP2010190193A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid transitional knocking caused by delay in response of a variable compression ratio mechanism in acceleration, in an internal combustion engine having the variable compression ratio mechanism and a variable valve train. <P>SOLUTION: Although intake valve closing timing (IVC) is controlled to be advanced from a bottom dead center in a low-load area, a target IVC is retarded to a knocking limit on a retard side in acceleration where a request load of an engine is suddenly increased. At this time, the IVC crosses an intake amount maximum intake valve closing timing IVCmax in which an intake amount in a cylinder becomes maximum, reduction correction of throttle valve opening is performed at the same time to avoid the transitional knocking. The IVC is controlled along the knocking limit corresponding to an actual mechanical compression ratio until the actual mechanical compression ratio is decreased to a target mechanical compression ratio. When it reaches the target mechanical compression ratio, it is set as a target IVC responding to the request load advanced from the bottom dead center. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including a variable compression ratio mechanism and a variable valve mechanism on the intake valve side.

  Various variable compression ratio mechanisms that can change the mechanical compression ratio of the engine, that is, the nominal compression ratio, are proposed in order to improve the thermal efficiency of the internal combustion engine in the low and medium load areas and to avoid knocking in the high load area. Has been. Various variable valve mechanisms that can change at least the intake valve closing timing in order to change the intake air amount actually entering the cylinder and the actual compression ratio have been proposed.

  And it is also possible to equip both such a variable compression ratio mechanism and a variable valve mechanism like patent documents 1-3, and in patent document 3, it is intake using a variable valve mechanism at the time of engine acceleration. It is disclosed that knocking at the initial stage of acceleration due to a delay of the variable valve mechanism is avoided by retarding the valve closing timing largely from the bottom dead center and suppressing the intake air amount.

JP 2006-46193 A JP 2004-218551 A JP 2004-239174 A

  In Patent Document 3, when the intake valve closing timing is set as the so-called early closing before the bottom dead center in a low load range immediately before acceleration, in the process of retarding the intake valve closing timing during engine acceleration. Since the intake valve closing timing crosses the bottom dead center and the actual compression ratio becomes transiently high, knocking at the initial stage of acceleration is rather deteriorated.

  Further, Patent Document 3 discloses an alternative example in which the intake valve closing timing is further advanced during engine acceleration to reduce the actual compression ratio. However, when the intake valve closing timing is so-called early closing in this way, so-called delay is achieved. As compared with the case of closing, the inertia of the intake air flowing into the cylinder as the piston descends makes it relatively easy to cause knocking even with the same intake amount. That is, as a knock limit of the intake air amount, so-called early closing makes the intake air amount small, which is disadvantageous in terms of acceleration response.

  An internal combustion engine to which the present invention is applied includes a variable compression ratio mechanism that changes its mechanical compression ratio, a variable valve mechanism that can change at least the closing timing of an intake valve before and after bottom dead center, and a throttle valve And.

  As a control device for the internal combustion engine, target mechanical compression ratio setting means for setting a target mechanical compression ratio according to engine operating conditions, and an actual mechanical compression ratio that changes with a delay at the time of transition are detected. Mechanical compression ratio detection means, basic target intake valve closing timing setting means for setting the basic target intake valve closing timing according to the engine operating state, acceleration detection means for detecting a sudden increase in the required load of the internal combustion engine, When the required load increases, the in-cylinder intake amount after bottom dead center is maximized. The predetermined intake amount at which the maximum intake valve closes. The knocking limit intake valve close timing that is retarded from the maximum intake valve close timing. A target intake valve closing timing correcting means for setting the valve closing timing and converging the target intake valve closing timing to the basic target intake valve closing timing as the actual mechanical compression ratio decreases, and the required load increase Sometimes the target intake valve closing timing is Throttle valve opening correction means for temporarily decreasing and correcting the throttle valve opening during a period corresponding to a timing when the maximum air intake valve closing timing changes from the advance side to the retard side. .

  For example, from a state where the engine is in a relatively low load range and the mechanical compression ratio is controlled to be high and the intake air intake closing timing is before the bottom dead center as a so-called early closing, the engine accelerates, that is, the required load suddenly increases. When the increase is made, the target mechanical compression ratio becomes a low compression ratio. The variable compression ratio mechanism operates so as to follow this, and the actual mechanical compression ratio gradually decreases. On the other hand, the target intake valve closing timing is once delayed from the position before the bottom dead center before acceleration to the knocking limit intake valve closing timing after the bottom dead center (or further retarded), and then after acceleration It converges to the basic target intake valve closing timing corresponding to the operating state as the actual mechanical compression ratio decreases. In the process of delaying from the position before the bottom dead center to the knocking limit intake valve closing timing as described above, the intake amount maximum intake valve closing timing at which the intake amount becomes maximum (this is slightly lower than the bottom dead center). However, during this period, the throttle valve opening is temporarily reduced and corrected, and transient knocking is avoided.

  In general, when the operating state, for example, the load changes, the variable valve mechanism and the throttle valve are relatively responsive compared to the responsiveness of the variable compression ratio mechanism.

  According to the present invention, when the internal combustion engine is relatively suddenly accelerated, the intake air amount in the cylinder can be as large as possible while reliably suppressing knocking, and a good acceleration response can be obtained.

Structure explanatory drawing which shows an example of a variable compression ratio mechanism. Structure explanatory drawing which shows an example of a variable valve mechanism. The characteristic view which shows the characteristic of the intake air quantity with respect to the center angle and operating angle of a variable valve mechanism. The valve timing chart which shows an example of intake valve closing timing. The characteristic view which shows the example of a characteristic of the target mechanical compression ratio with respect to a driving | running state. The characteristic view which shows the example of a characteristic of the suction negative pressure with respect to a driving | running state. The characteristic view which shows the example of a characteristic of the basic target intake valve closing timing with respect to a driving | running state. The flowchart which shows the flow of the process for acceleration detection. The flowchart which shows the flow of the correction control at the time of acceleration. The time chart which shows an example of the change of each parameter at the time of acceleration.

    Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a variable compression ratio mechanism that can variably control a mechanical compression ratio (nominal compression ratio) included in an internal combustion engine according to the present invention. The variable compression ratio mechanism itself is known from the above-described Patent Document 1 and the like.

  This variable compression ratio mechanism uses a multi-link type piston-crank mechanism, and an upper link 5 having one end connected to a piston 3 sliding in a cylinder 2 of a cylinder block 1 via a piston pin 4; The lower link 9 is connected to the other end of the upper link 5 via a connecting pin 6 and is rotatably connected to the crankpin 8 of the crankshaft 7. In order to limit the degree of freedom of the lower link 9 A control link 11 having one end connected to the lower link 9 via a connecting pin 10 and the other end swingably supported by the internal combustion engine body. The position is variably controlled by the eccentric cam portion 13 of the control shaft 12.

  The control shaft 12 is disposed in parallel with the crankshaft 7 and is rotatably supported by the cylinder block 1. The control shaft 12 is driven in the rotational direction by an actuator 15 made of an electric motor via a gear mechanism 14 and its rotational position is controlled.

  In the variable compression ratio mechanism configured as described above, the swing support position of the lower end of the control link 11 changes depending on the rotational position of the control shaft 12, that is, the position of the eccentric cam portion 13, and the initial posture of the lower link 9 changes. Along with this, the top dead center position of the piston 3, and thus the compression ratio changes.

  The target mechanical compression ratio is controlled by the engine operating state, that is, mainly the engine speed and the required load. For example, as shown in FIG. 5, basically, the lower the load side, the higher the compression ratio, and the higher the load side. Controlled to a low compression ratio.

  FIG. 2 shows an example of a variable valve mechanism on the intake valve side similarly provided in the internal combustion engine. This is because the first variable valve mechanism 51 capable of continuously expanding and reducing the lift / operating angle of the intake valve and the second variable valve capable of continuously delaying the central angle of the operating angle. The variable valve mechanism 52 is combined. Since this variable valve mechanism is also known from the above-mentioned Patent Document 1, only its outline will be described.

  The first variable valve mechanism 51 that variably controls the lift / operating angle is rotatably supported by a drive shaft 22 driven by a crankshaft of an internal combustion engine, an eccentric cam 23 fixed to the drive shaft 22. The eccentric cam 23 includes a control shaft 32, a rocker arm 26 that is swingably supported by the eccentric cam portion 38 of the control shaft 32, and a swing cam 29 that contacts the tappet 30 of the intake valve 53. The rocker arm 26 is linked by a link arm 24, and the rocker arm 26 and the swing cam 29 are linked by a link member 28.

  The rocker arm 26 is supported at its substantially central portion by the eccentric cam portion 38 so as to be swingable, and the arm portion of the link arm 24 is linked to one end portion thereof via a connecting pin 25. The upper end portion of the link member 28 is linked to the end portion via a connecting pin 27. The eccentric cam portion 38 is eccentric from the axis of the control shaft 32, and accordingly, the rocking center of the rocker arm 26 changes according to the angular position of the control shaft 32.

  The swing cam 29 is rotatably supported by being fitted to the outer periphery of the drive shaft 22, and a lower end portion of the link member 28 is linked to an end portion extending laterally via a connecting pin 37. ing. On the lower surface of the swing cam 29, a base circle surface concentric with the drive shaft 22 and a cam surface extending in a predetermined curve from the base circle surface are continuously formed. These base circle surface and cam surface come into contact with the upper surface of the tappet 30 according to the swing position of the swing cam 29.

  The control shaft 32 is configured to rotate within a predetermined angle range by a lift / operating angle control actuator 33 provided at one end. The lift / operating angle control actuator 33 is composed of, for example, an electric motor that drives the control shaft 32 via the worm gear 35, and is controlled by a control signal from the control unit 54. The rotation angle of the control shaft 32 is detected by a control shaft sensor 34.

  According to the first variable valve mechanism 51, the lift and the operating angle of the intake valve 53 are continuously expanded and reduced simultaneously according to the rotational angle position of the control shaft 32.

  On the other hand, the second variable valve mechanism 52 that variably controls the center angle is configured such that the sprocket 42 provided at the front end portion of the drive shaft 22 is relative to the sprocket 42 and the drive shaft 22 within a predetermined angle range. And a phase control actuator 43 that is rotated in an automatic manner. The sprocket 42 is linked to the crankshaft via a timing chain or timing belt (not shown). The phase control actuator 43 is composed of, for example, a hydraulic rotary actuator, and is controlled by a control signal from the control unit 54 via a hydraulic control valve (not shown). The action of the phase control actuator 43 causes the sprocket 42 and the drive shaft 22 to rotate relative to each other, thereby delaying the lift center angle in the valve lift. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The control state of the second variable valve mechanism 52 is detected by a drive shaft sensor 36 that responds to the rotational position of the drive shaft 22.

  As described above, in the variable valve mechanism, the intake valve closing timing is continuously delayed and changed by variably controlling the lift / operating angle and the central angle, for example, as shown in FIG. In addition, the intake air amount in the cylinder can be variably controlled.

  FIG. 7 shows the basic characteristics of the target intake valve closing timing (IVC) with respect to the engine speed and the required load. The lower the low-speed and low-load side, the more advanced the intake valve closing timing is from the bottom dead center. It is on the side and is retarded to approach the bottom dead center as the load increases. That is, in the low-medium load region, the intake valve closing timing is so-called early closing closer to the advance side than the bottom dead center, as indicated by “IVC1” in FIG. 4 in order to reduce the effective compression ratio. As shown in the figure, the intake amount maximum intake valve closing timing IVCmax at which the in-cylinder intake amount is maximum is slightly retarded from the bottom dead center, and at the maximum load, the intake valve closing timing is near this IVCmax. Become. The intake valve closing timing indicated as “IVC2” is a reference example in the case of so-called late closing in order to reduce the effective compression ratio.

  The internal combustion engine further includes an electronically controlled throttle valve (not shown) in the intake passage. FIG. 6 shows an example of the characteristics of the suction negative pressure adjusted by the throttle valve, and the throttle valve opening is controlled so as to achieve the target suction negative pressure with respect to the engine speed and the required load.

  The present invention is not limited to a specific type of multi-link type variable compression ratio mechanism or a specific type of variable valve mechanism as shown in FIGS. 1 and 2, but various types of variable compression mechanisms. It can be applied in combination with a ratio mechanism or a variable valve mechanism.

  Next, correction control during acceleration, which is the main part of the present invention, will be described with reference to the flowcharts of FIGS. 8 and 9 and the time chart of FIG. The actual mechanical compression ratio is detected from, for example, the rotational angular displacement of the control shaft 12 of the variable compression ratio mechanism or the operation amount of the actuator 15. Further, the actual intake valve closing timing (actual IVC) is obtained from the signals of the control shaft sensor 34 and the drive shaft sensor 36 described above, for example.

  FIG. 8 is a flow chart for calculating a load change width for determining whether or not the acceleration is sudden such that there is a possibility of knocking. First, in step 1, whether or not the load is the first time, that is, the previous load is stored. If it is the first time, after clearing a starting load described later in step 2, the requested load at that time is stored as a new previous load.

  If it is not the first time, the process proceeds from step 1 to step 3, and the required load increment is obtained as the difference between the required load at that time and the previous load. In step 4, the required load increment is compared with a predetermined value ΔT, and if it is larger than the predetermined value ΔT, the process proceeds to step 5 to determine whether or not the starting load is stored. If the starting load is not stored, the previous load is set as the starting load in step 6, and the load change width is obtained as the difference between the requested load and the starting load at step 7. In step 4, if the required load increment is equal to or less than the predetermined value ΔT, it is determined that the acceleration is steady or slow acceleration or deceleration, and the process proceeds to step 2 to clear the starting load as described above.

  That is, in the process of FIG. 8, the requested load at that time and the previous load are sequentially compared to determine whether or not the acceleration is abrupt, and if it is abrupt acceleration, the load immediately before the start of acceleration is temporarily set as the starting load. And the load change width from this starting load to the present time is obtained. Note that the required load is obtained from, for example, an accelerator opening operated by the driver.

  FIG. 9 is a flowchart regarding correction control of the intake valve closing timing and the throttle valve opening during acceleration. In step 11, the state of the IVC retardation control flag shown in FIG. 10A is determined. This IVC retardation control flag indicates that the correction control during acceleration is being performed. Since the first time is 0, the process proceeds to step 12 and proceeds to step 12 to determine the load change width and the compression ratio at that time (the target machine just before acceleration). Whether or not there is a possibility of knocking from the estimated response delay of the variable compression ratio mechanism. If there is a possibility of knocking, the IVC retardation control flag is set to “1” in step 14 and then the process proceeds to step 18 and thereafter.

  If there is no risk of knocking due to a small load change range even if the acceleration is sudden to some extent, the process proceeds to Steps 15 to 17 and, as usual, according to the operating conditions, the mechanical compression ratio, the intake air The valve closing timing and the throttle valve opening are respectively controlled.

  On the other hand, in step 18 when there is a risk of knocking, a target mechanical compression ratio and a target intake air amount are obtained based on the operating conditions at that time. Here, the target mechanical compression ratio changes stepwise toward the low compression ratio side as shown in FIG. Further, the target intake air amount increases in a stepwise manner as indicated by broken lines in (c) and (h) of FIG.

  In step 19, the actual mechanical compression ratio is read, and in step 20, it is determined whether or not the actual mechanical compression ratio has reached the target mechanical compression ratio. If “NO” here, in step 21, the retard side target IVC is obtained based on the actual mechanical compression ratio at that time. The retard side target IVC is an intake valve closing timing that becomes a knocking limit (an appropriate margin may be added as necessary) under the actual mechanical compression ratio at that time. This is the intake valve closing timing at the knocking limit on the retard side (that is, on the IVC2 side in FIG. 4) with respect to the maximum intake amount closing timing IVCmax described in the above. Since the actual mechanical compression ratio gradually changes with a delay as shown in FIG. 10 (d) with respect to the step change in the target mechanical compression ratio, the retard side target IVC that is the knocking limit is also As shown in FIG. 10 (e), when the deviation from the target value of the mechanical compression ratio is the largest, it becomes the most retarded angle side and gradually advances with time.

  In step 22, the actual IVC obtained based on the control axis sensor 34 and the drive axis sensor 36 is read, and in step 23, it is determined whether or not this actual IVC has become the retard side target IVC. If “NO” here, the process proceeds to the step 24. Since the variable valve mechanism performs known feedback control along the given target values of the operating angle and the central angle, the actual IVC follows the retard side target IVC as shown in FIG. try to. Note that the delay of the actual IVC is slightly exaggerated between times t1 and t5.

  As is apparent from FIG. 10 (f), the actual IVC immediately before acceleration is before bottom dead center, and the retarded target IVC, which is the target intake valve closing timing immediately after acceleration, is greater than the intake amount maximum intake valve closing timing IVCmax. Therefore, the actual IVC always crosses the intake amount maximum intake valve closing timing IVCmax. That is, the actual IVC changes from the advance side to the retard side of the maximum intake air intake valve closing timing IVCmax at a time slightly delayed from the time t1, for example, around the time t3.

  In step 24, it is determined whether or not the actual IVC is retarded from the maximum intake valve closing timing IVCmax. If NO, the process proceeds to step 25 and the target throttle valve opening is maintained as it is. To do. On the other hand, if YES, the routine proceeds to step 26, where the target throttle valve opening is obtained based on the operating conditions at that time. That is, the throttle valve opening corresponding to the required load after acceleration is given as a target value. For example, Th0 in FIG. 10G indicates the target throttle opening corresponding to the required load.

  Further, in step 27, it is determined whether the actual intake air amount in the cylinder at that time exceeds a predetermined upper limit, and if it exceeds the upper limit, the process proceeds to step 28 and the target throttle valve opening is corrected to decrease. The change in the actual intake air amount is shown in FIG. 10 (h), but the actual intake air amount in step 27 is obtained by converting from the actual IVC, for example. The upper limit is indicated by a line Amax1 in FIG. 10 (h), which indicates a knocking limit when the intake valve closing timing is on the retard side with respect to the intake amount maximum intake valve closing timing IVCmax. This is expressed as the amount of intake air in the cylinder. Accordingly, during the period when the actual IVC is in the vicinity of the maximum intake valve closing timing IVCmax, the intake air amount in the cylinder tends to exceed the knocking limit Amax1 as shown by the symbol a in FIG. Since the throttle valve opening is corrected to decrease, the actual intake air amount is controlled along the knocking limit Amax1, and the occurrence of transient knocking is reliably avoided.

  In other words, the actual behavior is that, when sudden acceleration is performed, the throttle valve opening does not increase immediately, but instead increases after shrinking for a very short time, and this throttle valve opening is reduced. In the meantime, the intake valve closing timing exceeds the intake amount maximum intake valve closing timing IVCmax and is delayed to the knocking limit.

  In the example of FIG. 10, since the actual IVC reaches the retarded target IVC at time t5, the process proceeds from step 23 to step 29 to determine whether the actual intake air amount has reached the target intake air amount. Since the retard side target IVC is along the retarding limit knocking limit, as shown in FIG. 10 (h), the actual intake amount increases along the knocking limit Amax1 as the intake amount after time t5. To go.

  If it is determined in step 29 that the target intake air amount has been reached, the routine proceeds to step 30, where the retard side target IVC is fixedly held. That is, if the actual intake air amount becomes the target intake air amount as between the times t6 to t7 of (e) and (f) in FIG. 10, the target IVC and thus the actual IVC does not advance any further. In step 31, the normal throttle valve opening corresponding to the operating condition is obtained, and the process proceeds to step 17.

  In the example of FIG. 10, since the actual mechanical compression ratio reaches the target mechanical compression ratio at time t7, the determination in step 20 is YES, and the process proceeds to step 32 and thereafter. In step 32, the target IVC on the advance side corresponding to the operating condition at that time (that is, the basic target intake valve closing timing corresponding to the engine operating condition) is obtained. This is given as a value on the advance side with respect to the intake amount maximum intake valve closing timing IVCmax, in particular, as with the early closing IVC1 described in FIG. In step 33, the actual IVC is read, and in step 34, the normal throttle valve opening corresponding to the operating condition is obtained.

  Since the target IVC changes stepwise to the advance side target IVC as described above, the actual IVC advances at the times t7 to t9 in FIG. 10 (f). Then, it is determined whether or not the actual IVC has reached the advance target IVC, and the process proceeds to step 36 until the advance IV target IVC is reached. In step 36, the target throttle valve opening is corrected to decrease so that the actual intake air amount does not exceed the upper limit (here, the target intake air amount becomes the upper limit) by the same processing as in steps 27 and 28 described above. As is apparent from FIG. 10 (f), the actual IVC again crosses the intake amount maximum intake valve closing timing IVCmax between times t7 and t9, so that if there is no correction of the throttle valve opening, As indicated by reference sign b, the intake air amount in the cylinder is larger than the target intake air amount. By correcting the throttle valve opening to decrease in step 36, the actual intake air amount can be maintained at the target intake air amount. It should be noted that the correction of the throttle valve opening between times t7 and t9 is not always essential and can be omitted.

  When the actual IVC becomes the advance side target IVC and the determination in step 35 is YES, the process proceeds to step 37 and the IVC retard control flag is cleared. Thereby, the correction control during a series of accelerations ends.

  As described above, in the above-described embodiment, as illustrated in the time chart of FIG. 10, during acceleration, the intake valve closing timing is once corrected to the retard side, and gradually advances along the knocking limit. When the maximum intake valve closing timing IVCmax is crossed, the throttle valve opening is corrected to decrease, so that the maximum acceleration response can be avoided while reliably avoiding knocking against the response delay of the actual mechanical compression ratio. Can be secured. In particular, by setting the intake valve closing timing to the retard side of the intake amount maximum intake valve closing timing IVCmax, the intake amount can be given to a relatively high knocking limit indicated as Amax1 in FIG. The line indicated by the symbol Amax2 in the figure is the knocking limit when the intake valve closing timing is closer to the advance side than the maximum intake valve closing timing IVCmax as indicated by IVC1 in FIG. Since the intake valve closes on the way to the dead center, the intake amount is relatively smaller than the retarding side knocking limit Amax1. In the present invention, by controlling the intake air amount along the retarding side knock limit Amax1 where the intake air amount becomes relatively large, a high torque response to an increase in the required load can be obtained. In addition, the time chart of FIG. 10 represents each change on the assumption that the rotation speed is constant.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, A various change is possible. For example, in the above embodiment, when the actual IVC crosses the intake amount maximum intake valve closing timing IVCmax, the throttle valve opening is corrected to decrease. However, the responsiveness of the variable valve mechanism is sufficiently higher than that of the variable compression ratio mechanism. If the response delay is high and neglects the response delay, the actual IVC is not particularly calculated, and the target IVC is simplified to correct the decrease in the throttle valve opening when the target intake valve crosses the maximum intake valve closing timing IVCmax. You can also.

  Further, instead of obtaining the actual intake air amount as in steps 27 and 36, the reduction correction amount obtained from the operating conditions, the actual mechanical compression ratio, etc. may be simply added to the throttle valve opening.

DESCRIPTION OF SYMBOLS 12 ... Control shaft 15 ... Actuator 33 ... Actuator for lift / operation angle control 43 ... Actuator for phase control 51 ... First variable valve mechanism 52 ... Second variable valve mechanism

Claims (5)

A variable compression ratio mechanism for changing the mechanical compression ratio of the internal combustion engine;
A variable valve mechanism that can change at least the closing timing of the intake valve before and after bottom dead center;
A throttle valve,
In an internal combustion engine with
A target mechanical compression ratio setting means for setting a target mechanical compression ratio according to engine operating conditions;
An actual mechanical compression ratio detection means for detecting an actual mechanical compression ratio that changes with a delay during a transition;
Basic target intake valve closing timing setting means for setting the basic target intake valve closing timing according to the engine operating state;
Acceleration detecting means for detecting a sudden increase in the required load of the internal combustion engine;
When the required load increases, the in-cylinder intake amount after bottom dead center is maximized. The predetermined intake amount at which the maximum intake valve closes. A target intake valve closing timing correcting means for setting the valve closing timing and converging the target intake valve closing timing to the basic target intake valve closing timing as the actual mechanical compression ratio decreases;
When the required load increases, the throttle valve opening is in a period corresponding to the timing when the target intake valve closing timing or actual intake valve closing timing changes from the advance side to the retard side of the intake amount maximum intake valve closing timing. Throttle valve opening correction means for correcting the degree of decrease temporarily,
A control device for an internal combustion engine comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the target intake valve closing timing correcting means sequentially sets a knocking limit intake valve closing timing according to an actual mechanical compression ratio as a target intake valve closing timing. .   2. The target intake valve closing timing correcting means sets the basic target intake valve closing timing as a target intake valve closing timing when an actual mechanical compression ratio reaches a target mechanical compression ratio. Or the control apparatus for an internal combustion engine according to 2;   When the basic target intake valve closing timing corresponding to the required load is on the more advanced side than the intake amount maximum intake valve closing timing, the throttle valve opening correction means is configured to perform the target intake valve closing timing or the actual intake valve closing timing. The throttle valve opening is temporarily reduced and corrected in a period corresponding to a timing when the timing changes from the retard side to the advance side of the maximum intake valve closing timing. 4. The control apparatus for an internal combustion engine according to any one of 3 above.   5. The throttle valve opening reduction correction is performed when the estimated or detected in-cylinder intake amount exceeds a knocking limit intake amount determined from an actual mechanical compression ratio at that time. The control apparatus of the internal combustion engine in any one.

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