JP2007002699A - 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 varying the valve overlap period with high responsiveness in an internal combustion engine provided with variable valve gears of which valve opening characteristics are variable on the intake side and the exhaust side. <P>SOLUTION: This device is provided with an intake variable valve train capable of varying valve characteristics of an intake valve, and an exhaust variable valve train capable of varying valve opening characteristics of an exhaust valve. Upon confirming establishment of F/C start conditions (figure 5(A)), the exhaust variable valve train 30 in which control is necessary on the delay side is selected, not the intake variable valve train 28 in which control is necessary on the advance side, as an actuator to generate desired valve overlap (figure 5(E)). Upon detecting a request for restoration from F/C by a request for acceleration (figure (A)), the intake variable valve train 28 on the delay control side is selected as an actuator for eliminating the valve overlap. (figure 5(D)). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus suitable as an apparatus for controlling an internal combustion engine having a variable valve mechanism that can change the valve opening characteristics of an intake valve and an exhaust valve.

  Conventionally, for example, Patent Document 1 discloses a control device for an internal combustion engine including a hydraulically driven variable valve timing mechanism as a valve operating mechanism for driving an intake valve. The cam shaft of the internal combustion engine drives the valve while receiving a reaction force when the cam pushes the valve lifter. Therefore, the variable valve timing mechanism has a responsiveness when changing the valve timing in the direction opposite to the reaction force from the valve lifter, that is, in the advance direction in the conventional mechanism, in the retard direction. It has a characteristic that it is not good as compared with the response when changing. Therefore, in the above-described conventional apparatus, the target advance angle amount at the time of acceleration / deceleration is determined in consideration of such characteristics of the variable valve timing mechanism.

  More specifically, the conventional apparatus has the following control in order to obtain high responsiveness of the valve timing during acceleration and deceleration. That is, in the case of deceleration that is often controlled in the retarding direction, the target advance amount is acquired based on a map that defines the relationship between the intake air amount and the engine speed. Further, in the case of acceleration that is often controlled in the advance direction, the target advance amount is acquired based on a map that defines the relationship between the throttle opening and the engine speed.

JP-A-6-330716 JP 2004-360550 A JP-A-11-218035 JP 2000-199440 A

  By the way, there is known an internal combustion engine provided with variable valve mechanisms (including the variable valve timing mechanism) that can change the valve opening characteristics on the intake side and the exhaust side, respectively. In such an internal combustion engine, for example, under an operating condition such as when fuel cut is introduced or when it is restored, there is a demand for changing the valve overlap period with high responsiveness.

  According to the above-described conventional apparatus, by considering the characteristics of the variable valve timing mechanism, it is possible to improve the useless control amount and control delay of the variable valve timing mechanism due to the characteristics. However, when the above prior art is applied to an internal combustion engine having variable valve mechanisms on the intake side and the exhaust side, the variable valve mechanisms on the intake side and the exhaust side are properly used to increase the valve overlap period. There was still room for consideration in terms of changing the response.

  The present invention has been made to solve the above-described problems. In an internal combustion engine provided with variable valve gears that can change the valve opening characteristics on the intake side and the exhaust side, respectively, the valve overlap period is increased. An object of the present invention is to provide a control device for an internal combustion engine that can be changed with high responsiveness.

In order to achieve the above object, the first invention provides an intake variable valve mechanism that varies the valve opening characteristics of the intake valve;
An exhaust variable valve mechanism that varies the valve opening characteristics of the exhaust valve;
A request to detect a valve overlap change request in a direction to increase the valve overlap period in which the intake valve open period and the exhaust valve open period overlap and / or to detect a valve overlap change request in a direction to decrease the valve overlap period Detection means;
Selecting means for selecting a variable valve mechanism having a higher responsiveness from the intake variable valve mechanism and the exhaust variable valve mechanism according to the direction of the valve overlap change request;
Command means for giving a command to change the valve overlap period to the variable valve mechanism using at least the variable valve mechanism selected by the selection means;
It is characterized by providing.

  In addition, the second invention is the first invention selected as the variable valve mechanism having higher responsiveness when the valve overlap is applied after the valve overlap is given by the command means. 1) At least a second variable valve mechanism that is not a variable valve mechanism is used, and the second variable valve mechanism is used as a main variable valve mechanism, and an overlap maintaining unit that maintains a given valve overlap is provided. It is characterized by that.

Further, a third invention is the first or second invention, in which fuel cut means for performing fuel cut at the time of deceleration of the internal combustion engine,
Variable valve timing control means for driving at least one of the intake variable valve mechanism and the exhaust variable valve mechanism to increase or decrease the exhaust gas recirculation amount;
The valve overlap change request in the direction of increasing the valve overlap is issued when a fuel cut is introduced.

According to a fourth aspect of the present invention, in any one of the first to third aspects, fuel cut means for performing fuel cut at the time of deceleration of the internal combustion engine;
Variable valve timing control means for driving at least one of the intake variable valve mechanism and the exhaust variable valve mechanism to increase or decrease the exhaust gas recirculation amount;
The valve overlap change request in the direction of decreasing the valve overlap is issued at the time of return from the fuel cut.

  According to the first aspect of the present invention, the variable valve mechanism having the higher response is selected from the intake variable valve mechanism and the exhaust variable valve mechanism in accordance with the direction of the valve overlap change request. The valve overlap period is changed using at least the variable valve mechanism. Therefore, according to the present invention, it is possible to change the valve overlap period with high responsiveness in an internal combustion engine provided with variable valve gears that can change the valve opening characteristics on the intake side and the exhaust side, respectively. Become.

  According to the second aspect of the present invention, when a valve overlap change request in a direction to reduce the valve overlap is issued after the valve overlap is given, the valve overlap period is changed with high responsiveness. Is possible.

  According to the third aspect of the invention, a desired valve overlap (internal EGR) can be generated with high responsiveness when the deceleration fuel cut is introduced. As a result, it is possible to bring out the catalyst deterioration suppressing effect over a longer period.

  According to the fourth aspect of the present invention, when returning from the deceleration fuel cut, it is possible to reduce the feeling of stagnation during acceleration after returning from the fuel cut while avoiding misfire.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining the configuration of the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine 10. A combustion chamber 12 is formed in the cylinder of the internal combustion engine 10. An intake passage 14 and an exhaust passage 16 communicate with the combustion chamber 12. A throttle valve 18 is disposed in the intake passage 14. The throttle valve 18 is an electronically controlled valve that is driven by a throttle motor based on the accelerator opening. A throttle position sensor 20 for detecting the throttle opening degree TA is disposed in the vicinity of the throttle valve 18.

  The internal combustion engine 10 is a multi-cylinder engine having a plurality of cylinders, and FIG. 1 shows a cross section of one of the cylinders. Each cylinder included in the internal combustion engine 10 is provided with an intake port that communicates with the intake passage 14 and an exhaust port that communicates with the exhaust passage 16. A fuel injection valve 22 for injecting fuel into the intake port is disposed in the intake port. The intake port and the exhaust port are provided with an intake valve 24 and an exhaust valve 26 for bringing the combustion chamber 12 and the intake passage 14 or the combustion chamber 12 and the exhaust passage 16 into a conductive state or a cut-off state, respectively. .

  The intake valve 24 and the exhaust valve 26 are driven by a hydraulic intake variable valve (VVT) mechanism 28 and an exhaust variable valve (VVT) mechanism 30, respectively. The variable valve mechanisms 28 and 30 respectively open and close the intake valve 24 and the exhaust valve 26 in synchronization with the rotation of the crankshaft, and change their valve opening characteristics (valve opening timing, operating angle, lift amount, etc.). can do.

  The internal combustion engine 10 includes a crank angle sensor 32 in the vicinity of the crankshaft. The crank angle sensor 32 is a sensor that reverses the Hi output and the Lo output each time the crankshaft rotates by a predetermined rotation angle. According to the output of the crank angle sensor 32, it is possible to detect the rotational position and rotational speed of the crankshaft, and further the engine rotational speed NE and the like. The internal combustion engine 10 also includes a cam angle sensor 34 in the vicinity of the intake camshaft. The cam angle sensor 34 is a sensor having the same configuration as the crank angle sensor 32. According to the output of the cam angle sensor 34, the rotational position (advance value) of the intake camshaft can be detected.

  An upstream catalyst (SC) 36 and a downstream catalyst (UF) 38 for purifying exhaust gas are arranged in series in the exhaust passage 16 of the internal combustion engine 10. An air-fuel ratio sensor 40 for detecting the exhaust air-fuel ratio at that position is disposed upstream of the upstream catalyst 36. Further, an oxygen sensor 42 that generates a signal corresponding to whether the air-fuel ratio at that position is rich or lean is disposed between the upstream catalyst 36 and the downstream catalyst 38.

  The system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50. In addition to the various sensors described above, the ECU 50 is connected to an accelerator position sensor 52 for detecting the accelerator pedal opening PA and the various actuators described above. The ECU 50 can control the operating state of the internal combustion engine 10 based on those sensor outputs.

[Overview of catalyst deterioration suppression control]
The system of the present embodiment configured as described above is a process for stopping the supply of fuel when the throttle opening TA is set to the idle opening during the operation of the internal combustion engine 10, that is, a fuel cut (F / F Perform C). Since fuel injection is not performed during execution of F / C, the gas flowing into the catalyst (upstream catalyst 36 and downstream catalyst 38) is extremely lean. When a lean gas flows into the high-temperature catalyst, the catalyst tends to deteriorate.

  According to the system shown in FIG. 1, the valve opening phase of the intake valve 24 is advanced by the intake variable valve mechanism 28 (more specifically, the valve opening timing is advanced). The period during which both the intake valve 24 and the exhaust valve 26 are open can be extended. Further, during the valve overlap period, instead of or at the same time as the advance angle of the valve opening phase of the intake valve 24, the valve opening phase of the exhaust valve 26 is retarded (more specifically, closed) by the variable exhaust valve mechanism 30. It can be extended by delaying the timing. If the valve overlap period is extended during execution of F / C during deceleration when the intake pipe pressure is negative, the amount of burned gas blown back into the intake passage 14 after the intake valve 24 is opened, that is, The amount of internal EGR increases.

  Accordingly, if the throttle opening degree TA is sufficiently reduced in a state where a sufficient valve overlap is generated, a sufficient exhaust gas recirculation amount (hereinafter referred to as an EGR gas amount) can be generated. Therefore, in the system of the present embodiment, during the execution of F / C, the throttle valve 18 is controlled to the fully closed position while introducing the EGR gas into the combustion chamber 12. According to such control, it is possible to effectively suppress the progress of deterioration of the catalyst while suppressing an excessive negative pressure of the intake pipe pressure. Hereinafter, such control, that is, control for suppressing deterioration of the catalyst by introducing the EGR gas into the combustion chamber 12 while keeping the throttle valve 18 fully closed during execution of F / C during deceleration, This is referred to as “catalyst deterioration suppression control”.

[Characteristics of Embodiment 1]
In order to bring out the effect of the catalyst deterioration suppression control as described above over a longer period of time, there is a demand for the throttle opening degree TA to be fully closed immediately after the F / C start condition is satisfied. However, in order to sufficiently throttle the throttle opening TA while suppressing an excessive negative pressure of the intake pipe pressure, a sufficient valve overlap is a prerequisite for this. Therefore, in order to further bring out the effect of the catalyst deterioration suppression control, the variable valve mechanisms 28 and 30 are required to have high responsiveness.

  In addition, when returning from F / C where the catalyst deterioration suppression control is being executed, the internal EGR is to be terminated rapidly in order to avoid a misfire and eliminate the feeling of acceleration after the F / C recovery. There is a request. That is, even in this case, the variable valve mechanisms 28 and 30 are required to have high responsiveness.

  FIG. 2 is a diagram for explaining the characteristics of the variable valve mechanisms 28 and 30 shown in FIG. As shown in FIG. 2A, the timing sprockets 60 and 62 of the variable valve mechanisms 28 and 30 described above are configured to rotate in synchronization with a crankshaft (not shown) via a chain 64. . The intake camshaft and exhaust camshaft (not shown) basically rotate in synchronization with the timing sprockets 60 and 62, respectively. The variable valve mechanisms 28 and 30 are adjusted so that relative rotation occurs between the timing sprocket 60 and the intake camshaft and the like by adjusting the hydraulic pressure in the hydraulic chambers (not shown) provided therein. It is configured.

  As shown in FIG. 2B, when the intake cam 66 pushes the valve lifter 68, the intake cam 66 receives a reaction force from the valve lifter 68. For this reason, the intake variable valve mechanism 28 is responsive to the reaction force from the valve lifter 68 in the direction against the reaction force from the valve lifter 68, that is, the responsiveness when changing the valve timing in the advance direction. That is, it has a characteristic that it is not as good as the response when changing the valve timing in the retard direction. In the case of the configuration of the present embodiment, the same applies to the configuration on the exhaust side shown in FIG. 2C, and the exhaust variable valve mechanism 30 is more responsive when changing the valve timing in the advance direction. Has a characteristic that it is not as good as when it is controlled in the retarding direction.

  Therefore, the system of the present embodiment uses the characteristics of the variable valve mechanisms 28 and 30 as described above to change the valve overlap period with high responsiveness at the time of F / C introduction or F / C return. In particular, the control described with reference to FIGS. 3 to 5 below is executed.

(1) Specific processing at the time of introduction of the deceleration F / C FIG. 3 is a flowchart of a routine executed by the ECU 50 at the time of introduction of the deceleration F / C in order to realize the above function. In the routine shown in FIG. 3, first, it is determined whether or not the deceleration F / C start condition is satisfied based on the accelerator opening PA (step 100). As a result, when it is determined that the deceleration F / C start condition is satisfied, it can be determined that a valve overlap change request in a direction to increase the valve overlap period has been issued. Therefore, the valve timing Ex-VVT of the exhaust valve 26 is then retarded to generate a desired internal EGR (step 102). That is, the valve overlap is given by the retardation of the exhaust valve timing Ex-VVT.

  Next, it is determined whether or not the valve timing Ex-VVT of the exhaust valve 26 has reached the target value (step 104). As a result, when it is recognized that the valve timing Ex-VVT of the exhaust valve 26 has reached the target value, that is, the advance amount of the Ex-VVT is reduced to a state where the occurrence of excessive intake pipe negative pressure can be suppressed. If it is determined that the throttle valve 18 has been reached, the throttle valve 18 is controlled to be fully closed in order to more effectively generate the catalyst deterioration suppressing effect (step 106). Next, it is determined whether or not the throttle opening degree TA has reached the fully closed target value (step 108).

  If it is determined in step 108 that the throttle opening degree TA has reached the fully closed target value, then after F / C is executed (step 110), the exhaust valve timing Ex-VVT and the intake valve timing Control for switching the control amount of In-VVT (hereinafter, simply referred to as “In, Ex switching control”) is executed (step 112).

  That is, in this step 112, while maintaining the internal EGR amount constant (that is, maintaining the valve overlap period constant), the actuator for generating such an internal EGR amount is the exhaust variable valve mechanism 30. To the intake variable valve mechanism 28. Specifically, the exhaust valve timing Ex-VVT and the intake valve timing In-VVT are advanced at the same speed. In the processing of this step 112, the exhaust valve timing Ex-VVT is retarded with respect to the advance amount during normal operation, and the intake valve timing with respect to the advance amount during normal operation. With the In-VVT advanced, the advance angle is adjusted to ensure the internal EGR amount. In the present specification, when valve overlap is generated using both variable valve mechanisms 28 and 30, the deviation between the advance amount during normal operation and the current advance amount becomes large. The variable valve mechanism that is controlled in this manner (in the case of this step 112, the intake variable valve mechanism 28) is referred to as "main variable valve mechanism".

(2) Specific processing at the time of return from deceleration F / C FIG. 4 is a flowchart of a routine that the ECU 50 executes at the time of return from the deceleration F / C in order to realize the above function. The routine shown in FIG. 4 is executed when the F / C is returned after the In / Ex switching control by the routine shown in FIG. 3 is completed. In the routine shown in FIG. 4, it is first determined whether or not there is a return request from the deceleration F / C based on the accelerator opening PA and the engine speed NE (step 200).

  If it is determined in step 200 that there is a return request from the deceleration F / C, it can be determined that a valve overlap change request for reducing the valve overlap period has been issued. Therefore, the intake valve timing In-VVT is then retarded to the advance amount during normal operation (step 202). At this time, the exhaust valve timing Ex-VVT is advanced to the advance amount during normal operation. Next, it is determined whether or not the advance value of the intake valve timing In-VVT has passed a predetermined misfire limit value (step 204). Here, the misfire limit value of the intake valve timing In-VVT is the value of the intake valve timing In-VVT that suppresses the occurrence of misfire etc. when returning from the deceleration F / C and ensures that combustion is possible. It is an advance value.

  When it is determined in step 204 that the advance amount of the intake valve timing In-VVT has passed the misfire limit value, the throttle opening TA is then opened to a predetermined opening (step 206). Then, the recovery process from the deceleration F / C is executed, that is, the fuel injection is resumed (step 208).

  FIG. 5 is a timing chart showing an example of operations realized by the processing of the routines shown in FIGS. More specifically, in FIGS. 5A to 5E, the state of the idle flag that determines whether or not the accelerator pedal is in the idle position is determined in order from the top, and the success or failure of the F / C execution is determined. The state of the F / C flag to be performed, and waveforms representing changes in the throttle opening TA, the intake valve timing In-VVT, and the exhaust valve timing Ex-VVT are shown.

  At time t0, when the accelerator pedal is returned as shown in FIG. 5A and the F / C start condition is confirmed, a desired valve overlap is generated as shown in FIG. 5E. An exhaust variable valve mechanism 30 that needs to be controlled on the retard side is selected instead of the intake variable valve mechanism 28 that needs to be controlled on the advance side. As a result, the exhaust valve timing Ex-VVT is retarded to a level at which negative pressure can be suppressed (time t1). When the exhaust valve timing Ex-VVT is retarded to a level at which negative pressure can be suppressed, the throttle valve 18 is controlled to be fully closed (FIG. 5C), and then F / C is executed (FIG. 5). 5 (B)). According to the characteristics of the variable valve mechanisms 28 and 30, as described above, the valve timing can be changed faster when the angle is retarded than when the angle is advanced. Therefore, according to the routine processing shown in FIG. 3, a desired valve overlap (internal EGR) can be generated with high responsiveness when the deceleration F / C is introduced. As a result, it is possible to bring out the catalyst deterioration suppressing effect over a longer period.

  When the exhaust valve timing Ex-VVT is retarded to a level at which negative pressure can be suppressed at time t1, the main actuator for generating the valve overlap is changed from the exhaust variable valve mechanism 30 to the intake variable valve mechanism. 28 (In, Ex exchange control, FIG. 5 (C, D)). According to such control, it is possible to select the intake variable valve mechanism 28 as an actuator having excellent responsiveness at the time of deceleration F / C recovery that is expected to arrive thereafter.

  After that, when a return request from the F / C is detected by an accelerator request at time t2 (FIG. 5A), an intake variable valve mechanism that becomes a variable valve mechanism with better responsiveness in this case By 28, the intake valve timing In-VVT is retarded so that the valve overlap is eliminated (FIG. 5D). At this time, the exhaust valve timing Ex-VVT is also advanced so as to be the amount of advance during normal operation (FIG. 5E). When the passage of the misfire limit is confirmed, the throttle opening degree TA is opened to a predetermined opening degree, and the return from the F / C is executed (FIGS. 5B and 5C). According to such control, it becomes possible to pass the misfire limit more quickly than in the case where the variable exhaust valve mechanism 30 which is the control to the advance side in this case is used as the main actuator. . For this reason, it is possible to reduce the feeling of stickiness during acceleration after returning from the deceleration F / C while avoiding misfire.

  By the way, in the first embodiment described above, when introducing the deceleration F / C, first, the exhaust valve timing Ex-VVT is retarded to a level at which negative pressure can be suppressed, and then the intake valve timing In-VVT is set. It is going to advance. However, in the present invention, the valve overlap is generated using at least the exhaust valve timing EX-VVT in the situation where the valve overlap is necessary (when the deceleration F / C is introduced in the first embodiment described above). If it is, it is not limited to the above methods. For example, when the F / C is introduced, the advance of the intake valve timing In-VVT may be started simultaneously with the delay start of the exhaust valve timing Ex-VVT or after the start of the delay. This is the same in the situation where the valve overlap is eliminated (when returning from the deceleration F / C in the first embodiment described above), and at the time of returning from the F / C, at least the intake valve timing. It is only necessary to eliminate valve overlap using In-VVT.

  In the first embodiment described above, the In and Ex replacement control is executed during the valve overlap occurrence period. In such In and Ex replacement control, the exhaust valve timing Ex-VVT is set. Instead, the method is not limited to the above method as long as the intake valve timing In-VVT functions as a main actuator for generating valve overlap. That is, in addition to the above method, for example, the exhaust valve timing Ex-VVT is returned to the advance amount during normal operation during the execution of the In / Ex switching control, and finally the intake valve timing In-VVT is set. The necessary valve overlap period may be maintained only by the advance angle.

  Further, in the first embodiment described above, as an example of an operating condition in which there is a request to realize the provision (increase) and cancellation (decrease) of the valve overlap period with high responsiveness, This is explained by taking the return time as an example. That is, the operating conditions to which the present invention is applied are not limited to those relating to the deceleration F / C. For example, during high-speed driving, there is a request to immediately eliminate valve overlap even when there is an accelerator request in a situation where an overlap period is increased to protect the catalyst and an internal EGR is introduced. Even in such a case, if the intake variable valve mechanism 28 is used as a main actuator during the valve overlap period and at least the intake valve timing In-VVT is advanced, the response to the accelerator request is high. It is possible to eliminate the valve overlap.

  Further, in the first embodiment described above, due to the reaction force received from the valve lifter 68 when the intake cam 66 or the like is driven by the intake valve 24 or the like, the operation on the advance side is compared with the operation on the retard side. Although the variable valve mechanisms 28 and 30 having the characteristic of slowing down are described, the variable valve mechanism to which the present invention is applied is not limited to this. That is, the present invention can also be applied to a configuration including a variable valve mechanism having a characteristic that the operation toward the advance side becomes faster than the operation toward the retard side. If the intake side variable valve mechanism has such characteristics, advance control using such an intake variable valve mechanism as the main variable valve mechanism is performed when the valve overlap is applied. Just do it. If the variable valve mechanism on the exhaust side has such characteristics, retard control using such an exhaust variable valve mechanism as the main variable valve mechanism may be performed when the valve overlap is resolved. .

In the first embodiment described above, the ECU 50 executes the processing of step 100 or 200, whereby the “request detection means” and the processing of step 102 or 202 in the first invention are executed. Thus, the “selecting means” and the “command means” in the first invention are realized.
Further, the ECU 50 executes the process of step 112, thereby realizing the “overlap maintaining means” in the second aspect of the invention, and in the example of step 112, the exhaust variable valve mechanism 30 is the first step. The intake variable valve mechanism 28 corresponds to the “first variable valve mechanism” in the second invention, and the intake variable valve mechanism 28 corresponds to the “second variable valve mechanism” in the second invention.
Further, when the ECU 50 executes F / C during deceleration of the internal combustion engine, the “fuel cut means” in the third or fourth invention drives the intake variable valve mechanism 28 and / or the exhaust variable valve mechanism 30. Thus, the “variable valve timing control means” in the third or fourth invention is realized by increasing or decreasing the internal EGR amount.

It is a figure for demonstrating the structure of Embodiment 1 of this invention. It is a figure for demonstrating the characteristic which the variable valve mechanism shown in FIG. 1 has. 4 is a flowchart of a routine that is executed when a deceleration F / C is introduced in the first embodiment of the present invention. 4 is a flowchart of a routine that is executed at the time of return from deceleration F / C in the first embodiment of the present invention. FIG. 5 is a timing chart showing an example of an operation realized by processing of the routine shown in FIGS. 3 and 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 14 Intake passage 16 Exhaust passage 18 Electronically controlled throttle valve 28 Intake variable valve mechanism (VVT) mechanism 30 Exhaust variable valve mechanism (VVT) mechanism 32 Crank angle sensor 34 Cam angle sensor 50 ECU (Electronic Control Unit)
68 Valve lifter

Claims (4)

An intake variable valve mechanism that varies the valve opening characteristics of the intake valve;
An exhaust variable valve mechanism that varies the valve opening characteristics of the exhaust valve;
A request to detect a valve overlap change request in a direction to increase the valve overlap period in which the intake valve open period and the exhaust valve open period overlap and / or to detect a valve overlap change request in a direction to decrease the valve overlap period Detection means;
Selecting means for selecting a variable valve mechanism having a higher responsiveness from the intake variable valve mechanism and the exhaust variable valve mechanism according to the direction of the valve overlap change request;
Command means for giving a command to change the valve overlap period to the variable valve mechanism using at least the variable valve mechanism selected by the selection means;
A control device for an internal combustion engine, comprising:   After the valve overlap is given by the command means, the second variable valve mechanism that is not the first variable valve mechanism selected as the variable valve mechanism that has high responsiveness when the valve overlap is given. 2. The control of the internal combustion engine according to claim 1, further comprising: an overlap maintaining means for maintaining the applied valve overlap, wherein at least the second variable valve mechanism is used as a main variable valve mechanism. apparatus. Fuel cut means for performing fuel cut during deceleration of the internal combustion engine;
Variable valve timing control means for driving at least one of the intake variable valve mechanism and the exhaust variable valve mechanism to increase or decrease the exhaust gas recirculation amount;
The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the valve overlap change request in the direction of increasing the valve overlap is issued when a fuel cut is introduced. Fuel cut means for performing fuel cut during deceleration of the internal combustion engine;
Variable valve timing control means for driving at least one of the intake variable valve mechanism and the exhaust variable valve mechanism to increase or decrease the exhaust gas recirculation amount;
The control of the internal combustion engine according to any one of claims 1 to 3, wherein the valve overlap change request in a direction to reduce the valve overlap is issued at the time of return from the fuel cut. apparatus.

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