JP2013047487A - Device for controlling variable valve mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for controlling a variable valve mechanism that prevents knocking in an internal combustion engine controlled to delay closing of a suction valved.SOLUTION: An internal combustion engine 1 includes a valve timing variable mechanism 13 for changing the timing to open a suction valve 9. A control device 26 performs closing delay control to close the suction valve 9 after a bottom dead center. During the closing delay control, the control device 26 sets the timing to close the suction valve 9 so that the higher the suction temperature is, the smaller the delay amount from the bottom dead center is.

Description

  The present invention relates to a control device for a variable valve mechanism.

  As described in Patent Document 1, an internal combustion engine including a variable valve mechanism that changes the closing timing of an intake valve is known. In the device disclosed in Patent Document 1, when knocking occurs, the valve closing timing of the intake valve is changed to the retard side to reduce the effective compression ratio, thereby suppressing the occurrence of knocking.

  Also, in recent internal combustion engines, the intake valve is closed after the piston reaches the intake bottom dead center, that is, the intake valve is controlled to be delayed, so that the substantial start of the compression stroke is delayed. Atkinson cycles that can achieve high expansion ratios may be implemented. In this Atkinson cycle, the thermal energy of the fuel is sufficiently converted into kinetic energy in the expansion stroke, so that the thermal efficiency of the internal combustion engine is improved.

JP 2010-138737 A

  When performing the above-described Atkinson cycle, the intake valve is closed after the intake bottom dead center, so that the intake air sucked into the cylinder is blown back to the intake port in the first half of the compression stroke. The intake air blown back at this time is the intake air once sucked into the cylinder, and its temperature is increased by receiving engine heat. Therefore, as the amount of intake air blown back to the intake port increases, the temperature of the intake air taken into the cylinder increases, and knocking is likely to occur.

  During the execution of such an Atkinson cycle, if the technique described in the above-mentioned document 1, that is, the technique of changing the closing timing of the intake valve to the retard side in order to suppress the occurrence of knocking, the intake air blown back to the intake port is applied. Therefore, the temperature of the intake air sucked into the cylinder increases, and knocking is more likely to occur.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a variable valve mechanism that can suppress the occurrence of knocking in an internal combustion engine in which intake valve slow closing control is performed. It is in.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is applied to an internal combustion engine having a variable valve mechanism for changing the closing timing of the intake valve, and the closing timing is set so that the closing timing is set to the retarded angle side from the intake bottom dead center. A control device for a variable valve mechanism that performs control, wherein during the execution of the delayed closing control, the valve closing timing is set so that the retarded amount from the intake bottom dead center decreases as the intake air temperature increases. The gist is to perform the closing timing setting process.

  According to this configuration, during the execution of the slow closing control, the closing timing of the intake valve is set so that the retard amount from the bottom dead center of the intake air becomes smaller as the intake air temperature becomes higher and knocking is likely to occur. As a result, the amount of intake air blown back is reduced, and the rise in intake air temperature is suppressed. Therefore, according to this configuration, it is possible to suppress the occurrence of knocking in the internal combustion engine in which the intake valve is slowly closed.

  As a more specific aspect of the valve closing timing setting process, the guard value for restricting the valve closing timing set based on the engine operating state to the advance side is an intake air as in the second aspect of the invention. A configuration in which the valve is set based on temperature, that is, a configuration in which the valve closing timing is limited by a guard value can be employed. In this configuration, it is desirable to set the guard value to be a value on the advance side as the intake air temperature is higher.

  Further, as a more specific aspect of the valve closing timing setting process, as in the invention according to claim 3, a correction value for correcting the valve closing timing set based on the engine operating state to the advance side. It is also possible to adopt a configuration in which is calculated based on the intake air temperature, that is, a configuration in which the valve closing timing is corrected to the advance side. In this configuration, it is desirable to calculate the correction value so that the valve closing timing is corrected to the more advanced side as the intake air temperature is higher.

  According to a fourth aspect of the present invention, in the control apparatus for a variable valve mechanism according to any one of the first to third aspects, the valve closing timing setting process is performed when the engine coolant temperature is equal to or higher than a predetermined temperature. The gist is to be executed.

  The invention according to claim 5 is the control device for the variable valve mechanism according to any one of claims 1 to 4, wherein the valve closing timing setting process is performed when the intake air temperature is equal to or higher than a predetermined temperature. The gist is to be executed.

  Knocking is likely to occur when the engine coolant temperature is equal to or higher than a predetermined temperature, that is, when the engine temperature is high, or when the intake air temperature is higher than a predetermined temperature. Therefore, by adopting the configuration according to the fourth or fifth aspect, the valve closing timing setting process can be executed when knocking is likely to occur. That is, it is possible to suitably determine whether or not the valve closing timing setting process is necessary.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a structure of an internal combustion engine to which a control device for a variable valve mechanism according to the present invention is embodied in a first embodiment. The graph which shows the relationship between the intake temperature in an intake port, and valve closing timing. The flowchart which shows the procedure about the setting process of the advance amount in the embodiment. The graph which shows the relationship between intake temperature and guard value in the embodiment. The flowchart which shows the procedure about the setting process of the advance amount in 2nd Embodiment. The graph which shows the relationship between intake temperature and correction value in the same embodiment.

(First embodiment)
Hereinafter, a first embodiment of a control device for a variable valve mechanism according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, in the internal combustion engine 1, air is sucked into the combustion chamber 2 through the intake passage 3 and the intake port 3 a, and fuel injected from the fuel injection valve 4 is supplied to the combustion chamber 2. When the air / fuel mixture is ignited by the spark plug 5, the air / fuel mixture burns, the piston 6 reciprocates, and the crankshaft 7 that is the output shaft of the internal combustion engine 1 rotates. The air-fuel mixture after combustion is discharged as exhaust gas from each combustion chamber 2 to the exhaust passage 8.

The intake passage 3 of the internal combustion engine 1 is provided with a throttle valve 29 for adjusting the intake air amount. The opening degree of the throttle valve 29 is adjusted by an electric motor.
The intake port 3a connected to the intake passage 3 and the combustion chamber 2 are connected and cut off by the opening / closing operation of the intake valve 9, and the exhaust port 8a connected to the exhaust passage 8 and the combustion chamber 2 are opened / closed. It is communicated and blocked by. The intake valve 9 and the exhaust valve 10 are opened and closed with the rotation of the intake camshaft 11 and the exhaust camshaft 12 to which the rotation of the crankshaft 7 is transmitted.

  The internal combustion engine 1 includes a variable valve timing mechanism (hereinafter referred to as VVT) 13 provided on an intake camshaft 11 as a variable valve mechanism that changes the valve characteristics of the intake valve 9. The VVT 13 adjusts the relative rotation phase of the intake camshaft 11 with respect to the crankshaft 7 to change the valve timing of the intake valve 9, so that the intake valve 9 is kept constant while the intake valve 9 is kept open. Both the valve opening timing IVO and the valve closing timing IVC are changed to the advance side or the retard side. Note that the most retarded phase of the VVT 13 is set to a phase at which the valve closing timing IVC of the intake valve 9 is greatly delayed from the intake bottom dead center. When the VVT 13 is controlled, the most retarded phase is set to “0”, and the advance amount AD from the most retarded phase is controlled. Therefore, as the advance amount AD is larger, the valve closing timing IVC of the intake valve 9 becomes an advance timing. The advance amount AD is a value set based on the engine operating state such as the engine load and the engine speed, and the VVT 13 is driven so that the set advance amount AD matches the actual advance amount. Is controlled.

  Various controls of the internal combustion engine 1 are performed by the control device 26. The control device 26 includes a CPU that executes arithmetic processing related to control of the internal combustion engine 1, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores arithmetic results of the CPU, and an external device. An input / output port for inputting / outputting a signal between them is provided.

Various sensors and switches shown below are connected to the input port of the control device 26.
An accelerator position sensor 28 that detects an operation amount (accelerator operation amount) of the accelerator pedal 27 that is operated by the driver of the vehicle.

A throttle position sensor 30 that detects the opening (throttle opening) of the throttle valve 29 provided in the intake passage 3.
An air flow meter 31 that detects the amount of air (intake air amount GA) sucked into the combustion chamber 2 through the intake passage 3.

An intake air temperature sensor 32 that detects the intake air temperature THA in the intake passage 3.
A water temperature sensor 33 that detects the cooling water temperature THW of the internal combustion engine 1.
A crank angle sensor 34 that detects the rotation angle of the crankshaft 7.

A cam position sensor 35 that detects the valve timing VT by outputting a signal corresponding to the rotational position of the camshaft.
A drive circuit such as an actuator for driving the electric motor of the throttle valve 29, the fuel injection valve 4, the spark plug 5, and the VVT 13 is connected to the output port of the control device 26.

  And the control apparatus 26 grasps | ascertains an engine operating state based on input signals, such as said various sensors, and outputs a command signal to the various drive circuits connected to the said output port according to the grasped engine operating state. Thus, control of the fuel injection amount by the fuel injection valve 4, control of the ignition timing of the spark plug 5, control of the valve timing of the intake valve 9, control of the opening degree of the throttle valve 29, and the like are performed through the control device 26.

  In the internal combustion engine 1 according to the present embodiment, the above-described Atkinson cycle is performed by performing the slow closing control of the intake valve by the VVT 13, that is, the control of closing the intake valve 9 on the retard side of the intake bottom dead center of the piston 6. To implement. In this Atkinson cycle, the closing timing of the intake valve 9 is later than the intake bottom dead center of the piston 6, so that the intake air sucked into the cylinder is blown back to the intake port 3a at the beginning of the compression stroke. As a result, the substantial start of the compression stroke is delayed, and as a result, a high expansion ratio can be obtained without increasing the actual compression ratio. And, in the Atkinson cycle that can increase the expansion ratio in this way, since the substantial piston stroke in the expansion stroke can be lengthened, the thermal energy of the fuel can be efficiently converted into kinetic energy, As a result, the thermal efficiency of the internal combustion engine 1 can be improved.

  By the way, as described above, when the Atkinson cycle is performed, the intake valve 9 is closed after the intake bottom dead center, so that the intake air sucked into the cylinder enters the intake port 3a in the first half of the compression stroke. Blown back. The intake air blown back at this time is the intake air once sucked into the cylinder, and its temperature is increased by receiving engine heat. Accordingly, as the amount of intake air blown back to the intake port 3a increases, the temperature of the intake air sucked into the cylinder increases, and knocking is likely to occur.

  As shown in FIG. 2, as the valve closing timing IVC of the intake valve 9 approaches the most retarded timing, the amount of intake air blown back to the intake port 3a increases. Therefore, the intake air temperature in the intake port 3a, that is, in the cylinder The temperature of the inhaled air intake increases. In addition, the intake air temperature in the intake port 3a increases as the intake air temperature THA in the intake passage 3 increases.

  Therefore, when the maximum temperature that can suppress the occurrence of knocking is set as the allowable temperature TK as the intake air temperature in the intake port 3a, the valve closing timing IVC that reaches the allowable temperature TK increases as the intake temperature THA increases. It's time. For example, in FIG. 2, the valve closing timing IVC that reaches the allowable temperature TK when “intake air temperature THA−middle” is the advance timing Gb from the most retarded timing, and when “intake air temperature THA−high”. The valve closing timing IVC at which the allowable temperature TK is reached becomes the timing Ga on the further advance side than the timing Gb. Therefore, when “intake air temperature THA−medium”, the valve closing timing IVC is limited so as not to be retarded from the timing Gb. When “intake air temperature THA−high”, the valve closing timing IVC is set to the timing Ga. By limiting the timing so as not to be at a more retarded angle than that, the occurrence of knocking during execution of the Atkinson cycle can be suppressed.

  Therefore, in this embodiment, the guard value G is set for the valve closing timing IVC. More specifically, the guard value G is set for the advance amount AD. Hereinafter, with reference to FIG. 3, a setting process of the advance amount AD that also sets the guard value G will be described. This setting process is repeatedly executed by the control device 26 at predetermined intervals.

  When this process is started, first, the advance amount AD is calculated based on the engine speed NE and the engine load KL (S100). Here, the advance angle amount AD is basically calculated so as to become smaller as the engine speed becomes lower and the load becomes lower, so that the Atkinson cycle is performed by the slow closing control of the intake valve 9 at the low engine speed and the low load.

  Next, it is determined whether or not the coolant temperature THW is equal to or higher than a determination value A (S110). As this determination value A, a value that can determine whether or not the engine temperature has risen to such an extent that the occurrence of knocking is a concern is set.

When the coolant temperature THW is less than the determination value A (S110: NO), this process is temporarily terminated.
On the other hand, when the coolant temperature THW is equal to or higher than the determination value A (S110: YES), it is determined whether the intake air temperature THA is equal to or higher than the determination value B (S120). As the determination value B, a value that can determine whether or not the intake air temperature has risen to such an extent that the occurrence of knocking is a concern is set.

When the intake air temperature THA is less than the determination value B (S120: NO), this process is temporarily terminated.
On the other hand, when the intake air temperature THA is equal to or higher than the determination value B (S120: YES), it is determined whether or not the current engine operation region is an execution region of the slow closing control of the intake valve 9 (S130). Here, for example, an affirmative determination is made when the intake air load factor (current intake air amount GA / intake air amount at full load) is equal to or less than a predetermined value and the engine operation region is in a low load region.

In step S130, when it is determined that it is not the execution region of the late closing control (S130: NO), this process is temporarily ended.
On the other hand, when it is determined that it is the execution region of the late closing control (S130: YES), since there is a concern about the occurrence of knocking due to the above-described blowback, the guard value G is set based on the intake air temperature THA. Performed (S140). This guard value G is a value that limits the amount of retardation from the intake bottom dead center for the closing timing IVC of the intake valve 9 during execution of the delayed closing control, and restricts the closing timing IVC to the advance side. This is a value that limits the amount of retardation from the intake bottom dead center to the advance side. In other words, by limiting the advance amount from the most retarded phase so as not to be smaller than the guard value G, the retard amount from the intake bottom dead center is limited. As shown in FIG. 4, the guard value G is variably set so that the guard value G increases as the intake air temperature THA increases, that is, increases toward the advance side.

  Next, it is determined whether or not the advance angle amount AD calculated in step S100 is smaller than the guard value G (S150). When the advance amount AD is equal to or greater than the guard value G (S150: NO), this process is temporarily terminated.

  On the other hand, when the advance amount AD is smaller than the guard value G (S150: YES), the valve closing timing IVC when the advance amount AD is applied is greater than the valve closing timing IVC when the guard value G is applied. However, there is a concern that the intake air temperature will rise due to blowback. Therefore, in order to set the valve closing timing IVC to a more advanced timing, the guard value G is set as the advance amount AD (S160), and this process is temporarily terminated. In addition, the process of step S140-step S160 comprises the said valve closing timing setting process.

  Incidentally, when the negative determination is made in step S100, step S120, step S130, or step S150, the occurrence of knocking can be suppressed without limiting the advance amount AD with the guard value G, so that the calculation is performed in step S100. The valve timing is controlled so that the advance amount AD is obtained.

Next, the operation of this embodiment will be described.
First, the valve timing ADC of the intake valve 9 is set by calculating the advance amount AD based on the engine operating state such as the engine speed NE and the engine load KL. Here, the guard value G that limits the valve closing timing IVC to the advance side by limiting the advance amount AD is calculated based on the intake air temperature THA. More specifically, the guard value G is set to be a value on the advance side as the intake air temperature THA is higher. Therefore, during the execution of the slow closing control of the intake valve 9, the closing timing IVC of the intake valve 9 is set so that the retard amount from the intake bottom dead center becomes smaller as the intake temperature THA becomes higher and knocking is more likely to occur. By being set, the amount of blow-back of intake air is reduced, and an increase in intake air temperature is suppressed. Therefore, the occurrence of knocking in the internal combustion engine 1 in which the intake valve 9 is controlled to be closed slowly is suppressed.

  Further, knocking is likely to occur when the cooling water temperature of the engine is higher than a predetermined temperature, that is, when the engine temperature is high, or when the intake air temperature is higher than the predetermined temperature. Therefore, when the coolant temperature THW is equal to or higher than the determination value A and the intake air temperature THA is equal to or higher than the determination value B, the above-described limit processing of the advance amount AD by the guard value G is performed. Accordingly, the closing timing setting process for setting the closing timing of the intake valve 9 so that the retard amount from the intake bottom dead center becomes smaller as the intake air temperature becomes higher is executed when knocking is likely to occur. It becomes possible. That is, it is appropriately determined whether or not the valve closing timing setting process is necessary.

As described above, according to the present embodiment, the following effects can be obtained.
(1) During execution of the delayed closing control of the intake valve 9, the valve closing timing for setting the valve closing timing IVC of the intake valve 9 so that the retard amount from the intake bottom dead center becomes smaller as the intake temperature THA becomes higher. Setting processing is performed. More specifically, the guard value G that limits the valve closing timing IVC set based on the engine operating state to the advance side is set based on the intake air temperature THA, that is, the valve closing timing IVC is the guard value G. Limited. Thereby, the amount of blow-back of the intake air is reduced, and the rise of the intake air temperature is suppressed. Accordingly, it is possible to suppress the occurrence of knocking in the internal combustion engine 1 in which the intake valve 9 is controlled to be slowly closed.

  (2) Knocking is likely to occur when the cooling water temperature of the engine is equal to or higher than a predetermined temperature, that is, when the engine temperature is high. Therefore, the valve closing timing setting process described above is executed when the engine coolant temperature THW is equal to or higher than the determination value A. Accordingly, it is possible to suitably determine whether or not the valve closing timing setting process is necessary.

(3) Further, knocking is likely to occur when the intake air temperature is higher than a predetermined temperature. Therefore, the valve closing timing setting process described above is executed when the intake air temperature THA is equal to or higher than the determination value B. Therefore, it is possible to suitably determine whether or not the valve closing timing setting process is necessary.
(Second Embodiment)
Next, a second embodiment in which the control device for the variable valve mechanism according to the present invention is embodied will be described with reference to FIGS.

  In the first embodiment, during the execution of the slow closing control of the intake valve 9, the closing timing IVC of the intake valve 9 is set so that the retard amount from the intake bottom dead center becomes smaller as the intake temperature THA becomes higher. In order to perform the valve closing timing setting process, the advance amount AD for determining the valve closing timing IVC is limited by the guard value G.

  On the other hand, in this embodiment, in order to perform such valve closing timing setting processing, a correction value K for correcting the advance amount AD for determining the valve closing timing IVC to the advance side is calculated. Only part of the setting process shown in FIG. Therefore, hereinafter, the setting process in the present embodiment will be described focusing on the differences from the setting process of the first embodiment.

  The advance amount setting process shown in FIG. 5 is also repeatedly executed by the control device 26 at predetermined intervals. In FIG. 5, the same step numbers are assigned to the same processes as those described in the first embodiment.

When this process is started, first, the advance amount AD is calculated based on the engine speed NE and the engine load KL (S100).
Next, it is determined whether or not the coolant temperature THW is equal to or higher than a determination value A (S110). When the coolant temperature THW is less than the determination value A (S110: NO), this process is temporarily terminated.

  On the other hand, when the coolant temperature THW is equal to or higher than the determination value A (S110: YES), it is determined whether the intake air temperature THA is equal to or higher than the determination value B (S120). When the intake air temperature THA is less than the determination value B (S120: NO), this process is temporarily terminated.

  On the other hand, when the intake air temperature THA is equal to or higher than the determination value B (S120: YES), it is determined whether or not the current engine operation region is an execution region of the slow closing control of the intake valve 9 (S130). Then, when it is determined that it is not the execution region of the late closing control (S130: NO), this process is temporarily ended. On the other hand, when it is determined that it is the execution region of the late closing control (S130: YES), there is a concern about the occurrence of knocking due to the blow-back as described above. Performed (S200). The correction value K is a value that further increases the advance amount AD calculated in step S100 in accordance with the intake air temperature THA during execution of the slow closing control. As shown in FIG. 6, the correction value K is variably set so that the correction value K increases as the intake air temperature THA increases.

  Next, the advance value AD is corrected by adding the correction value K to the advance value AD calculated in step S100 (S210), and this process is temporarily terminated. In this way, when the correction value K is added to the advance amount AD, the value of the advance amount AD increases, so that the valve closing timing IVC is set to a more advanced timing as compared to before the advance amount AD is corrected. Be changed.

In addition, the process of step S200 and step S210 comprises the said valve closing timing setting process in this embodiment.
Next, the operation of this embodiment will be described.

  First, the valve timing ADC of the intake valve 9 is set by calculating the advance amount AD based on the engine operating state such as the engine speed NE and the engine load KL. Here, by correcting the advance amount AD, a correction value K for correcting the valve closing timing IVC to the advance side is calculated based on the intake air temperature THA. More specifically, the correction value K is increased as the intake air temperature THA is higher, so that the valve closing timing IVC is corrected to the more advanced side as the intake air temperature THA is higher. Therefore, during the execution of the slow closing control of the intake valve 9, the closing timing IVC of the intake valve 9 is set so that the retard amount from the intake bottom dead center becomes smaller as the intake temperature THA becomes higher and knocking is more likely to occur. By being set, the amount of blow-back of intake air is reduced, and an increase in intake air temperature is suppressed. Therefore, the occurrence of knocking in the internal combustion engine 1 in which the intake valve 9 is controlled to be closed slowly is suppressed.

As described above, according to the present embodiment, in addition to the effects (2) and (3), the following effects can be obtained.
(4) During execution of the delayed closing control of the intake valve 9, the valve closing timing for setting the valve closing timing IVC of the intake valve 9 so that the retard amount from the intake bottom dead center becomes smaller as the intake temperature THA becomes higher. Setting processing is performed. More specifically, the correction value K for correcting the valve closing timing IVC, which is set based on the engine operating state, to the advance side is set based on the intake air temperature THA, so that the amount of return of intake air is reduced. Increase in intake air temperature is suppressed. Therefore, according to this embodiment, the occurrence of knocking can be suppressed in the internal combustion engine 1 in which the intake valve 9 is controlled to be closed slowly.

In addition, each said embodiment can also be changed and implemented as follows.
The correction value K described in the second embodiment is a value added to the advance amount AD, but may be a value to be multiplied. In the case of this modification, the minimum value of the correction value K is “1”, and the correction value K may be variably set so that the value increases as the intake air temperature THA increases.

-In 1st and 2nd embodiment, you may abbreviate | omit the process of step S110. Even in this case, effects other than the above (2) can be obtained.
-In 1st and 2nd embodiment, you may abbreviate | omit the process of step S120. Even in this case, effects other than the above (3) can be obtained.

  -In 1st and 2nd embodiment, you may abbreviate | omit the process of step S110 and step S120 together. Even in this case, effects other than the above (2) and (3) can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Combustion chamber, 3 ... Intake passage, 3a ... Intake port, 4 ... Fuel injection valve, 5 ... Spark plug, 6 ... Piston, 7 ... Crankshaft, 8 ... Exhaust passage, 8a ... Exhaust port, DESCRIPTION OF SYMBOLS 9 ... Intake valve, 10 ... Exhaust valve, 11 ... Intake cam shaft, 12 ... Exhaust cam shaft, 13 ... Valve timing variable mechanism (VVT), 26 ... Control device, 27 ... Accelerator pedal, 28 ... Accelerator position sensor, 29 ... Throttle valve, 30 ... throttle position sensor, 31 ... air flow meter, 32 ... intake air temperature sensor, 33 ... water temperature sensor, 34 ... crank angle sensor, 35 ... cam position sensor.

Claims (5)

Control of a variable valve mechanism that is applied to an internal combustion engine having a variable valve mechanism that changes the valve closing timing of the intake valve, and that performs a delay closing control that sets the valve closing timing to a retard angle side from the intake bottom dead center A device,
During the execution of the delayed closing control, a variable closing operation is performed in which the valve closing timing is set so that the retard amount from the intake bottom dead center decreases as the intake air temperature increases. Control device for valve mechanism. 2. The variable valve mechanism according to claim 1, wherein in the valve closing timing setting process, a guard value that limits the valve closing timing set based on an engine operating state to an advance side is set based on intake air temperature. Control device. 2. The variable valve mechanism according to claim 1, wherein in the valve closing timing setting process, a correction value for correcting the valve closing timing set based on an engine operating state to an advance side is calculated based on intake air temperature. Control device. The control device for a variable valve mechanism according to any one of claims 1 to 3, wherein the valve closing timing setting process is executed when a cooling water temperature of the engine is equal to or higher than a predetermined temperature. The control device for a variable valve mechanism according to any one of claims 1 to 4, wherein the valve closing timing setting process is executed when an intake air temperature is equal to or higher than a predetermined temperature.

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