JP2013050061A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a liquid fuel from adhering to an inner wall surface of a combustion chamber in cooling a port injection type internal combustion engine.SOLUTION: In cooling the internal combustion engine for executing an Atkinson cycle, an intake valve opening timing is adjusted to a timing when the occurrence of a reverse flow into an intake port starts (S106-114), so that sudden intake into a cylinder is not caused right after the intake valve is opened. The liquid fuel, which exists in a wall surface of the intake port or a back surface of the intake valve in cooling the internal combustion engine, is evaporated from the surface in the relatively mild airflow and is absorbed into the combustion chamber. As a result, the fuel is not absorbed into the cylinder while it is in a liquid state, which prevents the adhesion of the liquid fuel to the inner wall surface of the fuel chamber. Accordingly, combustion is not locally enriched, and PM generation is prevented.

Description

  The present invention relates to an internal combustion engine valve timing control apparatus that executes control for retarding an intake valve opening timing from TDC in accordance with an operating state of the internal combustion engine in an internal combustion engine that injects fuel into an intake port.

In a cold internal combustion engine, a technique for improving atomization of injected fuel and improving combustibility has been proposed (see, for example, Patent Documents 1 to 3).
In Patent Document 1, in order to improve fuel atomization in an internal combustion engine that is performing intake port fuel injection, intake balance is considered in consideration of the balance between fuel atomization promotion by heat reception at the intake port and fuel aggregation. If the valve opening timing is early, the fuel injection timing is also advanced, and if the intake valve opening timing is late, the fuel injection timing is also delayed.

In Patent Document 2, in an internal combustion engine that performs in-cylinder fuel injection, atomization is promoted by returning a part of the in-cylinder injected fuel to the intake port using the Atkinson cycle.
In Patent Document 3, when the internal combustion engine that is performing the intake port fuel injection is cold, atomization is promoted by controlling the fuel injection end timing according to the exhaust blowback amount from the intake valve. Further, in Patent Document 3, when the suction speed by the intake valve is slow, the fuel injection timing is brought close to the intake valve opening timing, and when the suction speed by the intake valve is fast, the fuel injection timing is kept away from the intake valve opening timing. In this way, the fuel adhering to the intake valve is put on the airflow by using the high suction speed and flows into the cylinder to reduce the residual unburned HC (hydrocarbon).

JP 2006-144753 A (page 4-7, FIGS. 3 and 4) JP 2009-174345 A (page 7-10, FIGS. 1 and 2) JP 2010-275932 A (pages 12-14, FIGS. 9 to 11)

  When the control is performed to retard the entire valve opening period of the intake valve and return the intake air once sucked into the cylinder to the intake port side again, such as the Atkinson cycle, the intake valve opening timing is Set after TDC. For this reason, the intake valve opens at the timing when the inside of the cylinder is in a negative pressure state. If the degree of retardation of the intake valve opening timing is large and the differential pressure between the intake port and the cylinder is large, intake air suddenly enters the cylinder from the intake port immediately after the intake valve opens. A flowing state occurs.

  When such an abrupt intake flow occurs in the cold state, the liquid fuel adhering to the intake port wall surface or the back surface of the intake valve is blown off by the fuel injection, and is sucked into the cylinder in a liquid state. For this reason, the situation which a liquid fuel adheres to the inner wall face of a combustion chamber generate | occur | produces.

If it burns in this state, it will become combustion in a local rich state, and will cause PM (particulate matter: particulate matter) generation.
In Patent Document 1, control is performed in consideration of fuel atomization at the intake port, and even when the intake valve opening timing is after TDC, the fuel injection timing is only controlled to the retard side. For this reason, no measures are taken against the liquid fuel sucked into the cylinder immediately after the intake valve is opened in the cold state and adhered to the inner wall surface of the combustion chamber. Therefore, there is no PM prevention effect.

  In Patent Literature 2, a part of the fuel that is injected and floated in a cylinder is returned to the intake port side after BDC by using the Atkinson cycle. For this reason, the liquid fuel sucked from the intake port side after TDC and attached to the inner wall surface of the combustion chamber does not return to the intake port side. Therefore, since no countermeasure is taken for such a liquid fuel, there is no PM prevention effect.

  In Patent Document 3, control is performed in consideration of the suction speed of the intake valve in a state where there is no exhaust blowback. The purpose of this control is to suck the fuel and place it in the cylinder. Therefore, liquid fuel that has adhered to the inner wall surface of the combustion chamber due to cold suction is not considered. For this reason, there is no PM prevention effect.

  An object of the present invention is to prevent liquid fuel from adhering to the inner wall surface of a combustion chamber when the internal combustion engine is cold.

In the following, means for achieving the above-mentioned purpose, and its operation and effect are described.
The internal combustion engine valve timing control apparatus according to claim 1, wherein an internal combustion engine that injects fuel into an intake port executes control for retarding an intake valve opening timing from TDC in accordance with an operating state of the internal combustion engine. An engine valve timing control device, in which when the internal combustion engine is cold, the cylinder valve pressure at the intake valve opening timing is equal to or higher than the pressure of the intake port, and the intake valve opening timing and exhaust A cold time valve timing setting means for adjusting one or both of the valve closing timings is provided.

  When the control for delaying the intake valve opening timing from the TDC is executed in accordance with the operating state of the internal combustion engine as described above, the liquid fuel adhering to the wall surface of the intake port or the back surface of the intake valve when cold. However, it may be sucked into the cylinder by a sudden suction flow generated immediately after the intake valve is opened, and may adhere to the inner wall surface of the combustion chamber.

  However, in the present invention, the cold valve timing setting means sets the intake valve to a state where the in-cylinder pressure at the intake valve opening timing is equal to or higher than the pressure of the intake port when the internal combustion engine is cold. Adjust one or both of the valve opening timing and the exhaust valve closing timing. For this reason, an abrupt suction flow does not occur immediately after the intake valve opens, and an intake flow suction occurs thereafter.

  For this reason, when it is cold, the fuel that was present as liquid on the intake port wall and the back of the intake valve is not sucked into the cylinder in liquid form, but is sucked into the cylinder in a sufficiently atomized state. become. Therefore, liquid fuel can be prevented from adhering to the inner wall surface of the combustion chamber when the internal combustion engine is cold. This can prevent the generation of PM.

  The internal combustion engine valve timing control device according to claim 2, wherein the cold valve timing setting means is configured to approach the target state when the internal combustion engine is cold. The intake valve opening timing is adjusted.

  Thus, the cold time valve timing setting means controls the target state by adjusting only the intake valve opening timing. By adjusting only the intake valve opening timing in this way, it is possible to prevent a sudden suction flow from occurring immediately after the intake valve is opened. Therefore, liquid fuel can be prevented from adhering to the inner wall surface of the combustion chamber when the internal combustion engine is cold.

  The internal combustion engine valve timing control device according to claim 3, wherein the cold valve timing setting means detects an airflow reverse flow state at the intake port. When the internal combustion engine is cold, when the intake port reverse flow detection means does not detect the occurrence of the reverse flow, the intake valve open timing is advanced to detect the occurrence of the reverse flow. In this case, the intake valve opening timing is retarded.

By such a method, the cold time valve timing setting means can adjust the intake valve opening timing so as to be in the target state.
That is, the cold valve timing setting means sets the intake valve opening timing so that the intake valve opens in a state immediately before the occurrence of backflow in the intake port, that is, in a state in which exhaust blowback begins to occur from the combustion chamber. It controls the advance / retard angle. The state in which exhaust blow-back begins to occur from the combustion chamber can be achieved because the in-cylinder pressure is equal to the pressure of the intake port or a slightly higher in-cylinder pressure.

  In this way, by controlling the intake valve opening timing in accordance with the detection state of the intake port backflow detecting means, it is possible to prevent a sudden suction flow from occurring immediately after the intake valve is opened. Therefore, liquid fuel can be prevented from adhering to the inner wall surface of the combustion chamber when the internal combustion engine is cold.

Further, when the backflow is detected, the intake valve opening timing is retarded and the backflow is not strengthened more than necessary, so that deterioration of fuel consumption can be prevented.
5. The internal combustion engine valve timing control apparatus according to claim 4, wherein the cold valve timing setting means detects an airflow backflow state at an intake port. When the internal combustion engine is cold, when the intake port reverse flow detection means does not detect the occurrence of the reverse flow, the intake valve open timing is advanced to detect the occurrence of the reverse flow. In this case, adjustment to the intake valve opening timing is not executed.

  The cold valve timing setting means advances the intake valve opening timing only when no backflow occurs, and does not adjust the intake valve opening timing when the occurrence of backflow is detected. . That is, only the advance side is adjusted without adjusting the retard side.

  When reverse flow, that is, exhaust blowback occurs, at least the in-cylinder pressure is higher than the intake port pressure. From this, the target state can be achieved only by adjusting to the advance side, which is executed when the occurrence of backflow is not detected.

This can prevent the liquid fuel from adhering to the inner wall surface of the combustion chamber when the internal combustion engine is cold.
6. The internal combustion engine valve timing control apparatus according to claim 5, wherein the cold valve timing setting means detects an airflow backflow state at an intake port. When the internal combustion engine is cold and the intake port backflow detection means does not detect the occurrence of backflow immediately after the intake valve opening timing, the intake valve opening timing is set to an advance value corresponding to the target state. When the occurrence of backflow is detected, adjustment to the intake valve opening timing is not executed.

  As described above, the cold valve timing setting means immediately sets the intake valve opening timing to the advance value corresponding to the target state when the intake port backflow detection means does not detect the occurrence of the backflow.

As a result, the rapid suction prevention process can be performed quickly, so that liquid fuel can be more reliably prevented from adhering to the inner wall surface of the combustion chamber when the internal combustion engine is cold.
The internal combustion engine valve timing control device according to claim 6 is the internal combustion engine valve timing control device according to any one of claims 1 to 5, wherein the intake valve opening timing is retarded from TDC as an Atkinson cycle. It is characterized by executing control to perform.

  As control for retarding the intake valve opening timing from TDC, execution of the Atkinson cycle can be mentioned. Therefore, when the Atkinson cycle is executed when the internal combustion engine is cold, liquid fuel adhesion to the inner wall surface of the combustion chamber is prevented.

  The internal combustion engine valve timing control device according to claim 7, wherein the cold valve timing setting means includes an intake valve opening timing and an internal combustion engine valve timing control device according to any one of claims 1 to 6. The present invention is characterized by comprising torque fluctuation suppressing means for suppressing fluctuations in the output torque of the internal combustion engine that occur when one or both of the exhaust valve closing timings are adjusted and controlled to the target state.

  When the cold time valve timing setting means adjusts one or both of the intake valve opening timing and the exhaust valve closing timing, output torque fluctuations may occur in the internal combustion engine. In such a case, the output torque fluctuation of the internal combustion engine is suppressed by the torque fluctuation suppressing means. Thus, if the shock applied to the apparatus to which the internal combustion engine is applied, for example, if the internal combustion engine is applied to the vehicle, the shock to the vehicle can be prevented, thereby preventing the passenger from feeling uncomfortable.

1 is a schematic configuration diagram of an internal combustion engine and a control system thereof according to Embodiment 1. FIG. The graph which shows the relationship between the airflow state immediately after the intake valve opening in the change of the intake valve opening timing advance value VT, and the amount of PM generated in the combustion chamber. 6 is a flowchart of cold-intake valve opening timing setting processing executed by the ECU according to the first embodiment. (A)-(C) The graph which shows an example of control of Embodiment 1. FIG. FIG. 9 is a flowchart of cold intake valve opening timing setting processing according to the second embodiment. FIG. FIG. 9 is a flowchart of cold intake valve opening timing setting processing according to Embodiment 3. FIG. 10 is a flowchart of output torque fluctuation prevention processing according to the fourth embodiment. FIG. 6 is a schematic configuration diagram of an internal combustion engine and a control system thereof according to a fifth embodiment. 19 is a flowchart illustrating an example of a cold exhaust valve closing timing setting process according to a sixth embodiment. 19 is a flowchart illustrating an example of a cold exhaust valve closing timing setting process according to a sixth embodiment. 19 is a flowchart illustrating an example of a cold exhaust valve closing timing setting process according to a sixth embodiment. (A), (B) The graph which shows the temperature rise state by the backflow presence or absence of an intake port.

[Embodiment 1]
<Configuration of Embodiment 1> FIG. 1 shows a schematic configuration of an internal combustion engine 2 to which the above-described invention is applied and an electronic control unit (hereinafter referred to as “ECU”) 4 as a control system thereof. The internal combustion engine 2 is a gasoline engine and is mounted on the vehicle for driving the vehicle. The internal combustion engine 2 has a plurality of cylinders. For example, it is configured as an inline 4-cylinder gasoline engine. The number of cylinders may be an internal combustion engine having another number of cylinders such as 6 cylinders or 8 cylinders, or a V-type internal combustion engine. FIG. 1 shows only one cylinder among the plurality of cylinders.

  Each combustion chamber 6 of the internal combustion engine 2 is connected to an intake system via an intake port 10 that is opened and closed by an intake valve 8, and is connected to an exhaust system via an exhaust port 14 that is opened and closed by an exhaust valve 12. Yes.

  A fuel injection valve 16 is provided in the intake port 10, and an air-fuel mixture is formed by injecting fuel into the intake air toward the intake valve 8 during fuel injection. An intake manifold 18 including a surge tank 18 a and a branch pipe 18 b is connected to the upstream side of the intake port 10. A throttle valve 20 is provided on the upstream side of the intake manifold 18.

  In the internal combustion engine 2, the intake air amount is adjusted by the lift amount of the intake valve 8. Therefore, although the opening degree of the throttle valve 20 can be adjusted by the motor 20a, it is normally fully opened when the internal combustion engine 2 is operated and fully closed when the internal combustion engine 2 is stopped. The throttle valve 20 is provided with a throttle opening sensor 20b for detecting the throttle opening TA. An intake air amount sensor 22 is provided upstream of the throttle valve 20 to detect the intake air amount GA.

  Fuel injection is performed by the fuel injection valve 16 to form an air-fuel mixture in the intake port 10, and this air-fuel mixture is drawn into the combustion chamber 6 when the intake valve 8 is opened. The air-fuel mixture in the combustion chamber 6 is combusted by ignition by spark of the spark plug 24 at the ignition timing. As a result, the piston 26 is pushed down to rotate the crankshaft 28 as an output shaft.

  The air-fuel mixture after combustion is discharged from the combustion chamber 6 to the exhaust port 14 as exhaust gas by opening the exhaust valve 12. The exhaust discharged in this way is discharged to the outside through an exhaust purification catalyst and a muffler.

  Here, a variable valve timing mechanism 32 is provided on the intake camshaft 30 that transmits the opening / closing driving force to the intake valve 8. The variable valve timing mechanism 32 adjusts the relative rotation phase of the intake camshaft 30 with respect to the crankshaft 28. Therefore, the valve timing of the intake valve 8 can be continuously advanced or retarded by the variable valve timing mechanism 32.

  Further, a variable lift amount mechanism 34 is provided between the intake camshaft 30 and the intake valve 8. The lift amount varying mechanism 34 continuously varies the maximum valve lift amount of the intake valve 8 in the intake stroke. Note that the change in the maximum valve lift corresponds to the change in the operating angle of the intake valve 8.

The variable valve timing mechanism 32 and the variable lift amount mechanism 34 described above form a variable valve mechanism for the intake valve 8.
The depression amount of the accelerator pedal 36 is detected as an accelerator operation amount ACCP by the accelerator operation amount sensor 36a. In accordance with the accelerator operation amount ACCP, the ECU 4 controls the lift amount variable mechanism 34 to adjust the maximum valve lift amount (or operating angle) of the intake valve 8. As a result, an air-fuel mixture corresponding to the amount of depression of the accelerator pedal 36 can be introduced into the combustion chamber 6. As a result, the output torque of the internal combustion engine 2 is adjusted.

The exhaust valve 12 receives a rotational driving force from an exhaust camshaft 38 that is rotated by the crankshaft 28.
The ECU 4 executes ignition timing control and other processes in addition to control of the fuel injection amount, fuel injection timing, intake air amount, and valve overlap of the internal combustion engine 2. For these processes, the ECU 4 inputs detection signals from the engine speed sensor 42, the cooling water temperature sensor 44, the throttle opening sensor 20b, the intake air amount sensor 22, the accelerator operation amount sensor 36a, the cam position sensor 30b, and the like. . In addition, a detection signal is input from an air-fuel ratio sensor provided in the exhaust system.

  The engine speed sensor 42 detects the engine speed NE corresponding to the rotation of the crankshaft 28, and the cooling water temperature sensor 44 detects the cooling water temperature THW as the engine temperature. A cam position sensor 30 b provided for the intake camshaft 30 detects the cam angle of the intake cam 30 a that drives the intake valve 8.

  The intake port 10 is provided with an intake port reverse flow detection sensor 46 in the vicinity of the intake valve 8. The intake port backflow detection sensor 46 is a sensor that detects whether or not a backflow of airflow from the combustion chamber 6 to the intake port 10 side occurs when the intake valve 8 is open.

  The intake port backflow detection sensor 46 is configured to have a gas inlet opening that opens on the intake valve 8 side, thereby detecting the flow rate and flow velocity of the gas flowing back from the combustion chamber 6 side to the intake port 10. A flow rate sensor or a flow rate sensor can be used. In addition, since the backflow from the intake valve 8 is a backflow of exhaust gas after combustion, a CO2 sensor for detecting the CO2 concentration or a temperature sensor for detecting the temperature of the hot exhaust gas can be used. In this case, the backflow can be detected by increasing the concentration of CO2 or increasing the temperature of the airflow.

  Even if a sensor is not used, the period during which the backflow due to the calculation occurs can be determined using the physical model of the internal combustion engine 2. Based on the above, the back flow rate or the back flow presence / absence may be calculated.

  When the intake port reverse flow detection sensor 46 is arranged as shown in FIG. 1 instead of the calculation based on the physical model, one cylinder is representative, and the intake port reverse flow detection sensor 46 is arranged only in the intake port 10 of this representative cylinder. A reverse flow state may be detected. In the present embodiment, it is assumed that the intake port backflow detection sensor 46 is disposed only in the # 1 cylinder to detect the presence or absence of backflow.

  The ECU 4 executes various controls based on the above-described signals, stored data, calculation results, and the like. That is, control of ignition timing by the spark plug 24, fuel injection amount and fuel injection timing by opening control of the fuel injection valve 16, valve timing of the intake valve 8, adjustment of lift amount of the intake valve 8, adjustment of opening of the throttle valve 20, and the like. Execute.

  According to the knowledge of the present inventor, in the operation of the internal combustion engine in the cold state, the airflow state in the intake valve 8 immediately after the intake valve 8 is opened (for example, the period from the intake valve opening timing to about 20 ° CA), It has been found that the relationship with the PM generation amount (g) in the combustion chamber 6 is as shown in FIG.

  That is, when the intake valve opening timing is on the retard side, the airflow immediately after the valve opening is forward, but when the valve opening timing is on the advance side, a reverse flow is generated. Then, it can be seen that the PM generation amount changes greatly in the boundary region between the reverse flow side and the forward flow side of the air flow, and the PM generation amount increases rapidly on the forward flow side.

  On the retard side of the intake valve opening timing, particularly in a state where the intake valve 8 is opened after TDC, the inside of the combustion chamber 6 is in a negative pressure state before the valve is opened. That is, the in-cylinder pressure (pressure in the combustion chamber 6) is lower than the pressure in the intake port 10. The decrease in the cylinder pressure becomes stronger as the intake valve opening timing is retarded.

Therefore, at the intake valve opening timing, a sudden suction flow is generated around the intake valve 8 due to the differential pressure between the intake port 10 and the in-cylinder pressure.
When the internal combustion engine is cold, the fuel injected from the fuel injection valve 16 adheres in liquid form to the back surface of the intake valve 8 and the wall surface of the intake port 10, and when a sudden suction flow occurs in such a state The fuel is blown off in a liquid state and sucked into the combustion chamber 6. Then, it adheres in liquid form to the inner wall of the combustion chamber 6 (particularly around the exhaust valve 12).

If combustion is performed in the combustion chamber 6 with the liquid fuel adhering to the inner surface, local rich combustion occurs, and the amount of PM generated in the combustion chamber 6 increases.
In order to prevent PM generation, it is necessary to perform control so that liquid fuel is not sucked into the combustion chamber 6 when it is cold. For this purpose, the ECU 4 executes a cold intake valve opening timing setting process (FIG. 3) based on the relationship of FIG.
<Operation of Embodiment 1> The operation of the present embodiment will be described based on a cold intake valve opening timing setting process (FIG. 3). This process is repeatedly executed at a constant crank angle period (or a constant time period). The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When this process is started, it is first determined whether or not the internal combustion engine 2 is in cold operation (S102). This is determined by whether or not the coolant temperature THW detected by the coolant temperature sensor 44 is equal to or lower than a reference temperature.

If it is not cold (NO in S102), the process is exited.
If it is cold (YES in S102), it is next determined whether or not the intake valve 8 of the # 1 cylinder is open (S104). The valve opening period of the # 1 cylinder can be calculated by the crank angle (° CA) from the control amounts of the valve timing variable mechanism 32 and the lift amount variable mechanism 34. It is possible to determine whether or not the intake valve 8 of the # 1 cylinder is in an open state from a comparison between this crank angle and the actual crank angle calculated from the signal of the engine speed sensor 42.

If the # 1 cylinder intake valve 8 is not open (NO in S104), the process is terminated.
Although it is cold (YES in S102), if the state in which the intake valve 8 of the # 1 cylinder is not opened continues (NO in S104), the state of exiting the process continues.

  When the intake valve 8 of # 1 cylinder is opened (YES in S104), whether or not the correction of the intake valve opening timing advance value VT at the time of this opening (step S110 or S114 described later) is incomplete Is determined (S105).

  The intake valve opening timing advance value VT indicates the advance amount from the reference valve opening timing. The larger the intake valve opening timing advance value VT, the faster the intake valve 8 opens, and the smaller the smaller, the slower the intake valve 8 opens.

  Since the intake valve opening timing advance value VT is not corrected when the # 1 cylinder intake valve 8 is initially opened (YES in S105), the intake port 10 of the # 1 cylinder is provided next. The output Udirec of the intake port backflow detection sensor 46 is read into the work memory of the ECU 4 (S106).

  Next, it is determined whether or not the value of the output Udirec indicates a reverse flow (S108). That is, it is determined whether or not the exhaust gas remaining in the combustion chamber 6 flows backward to the intake port 10 side through the opened intake valve 8.

  Here, it is assumed that the ECU 4 is executing the Atkinson cycle. It is assumed that the entire valve opening period of the intake valve 8 is greatly retarded by this Atkinson cycle, and the intake valve opening timing is considerably later than the TDC. In this state, immediately before the intake valve opening timing, the piston 26 is decreasing with both the intake valve 8 and the exhaust valve 12 being closed, so the inside of the combustion chamber 6 is in a negative pressure state.

  For this reason, immediately after the intake valve opening timing, intake air is suddenly sucked into the combustion chamber 6 from the intake port 10 side. Such a sudden suction is not a reverse flow but a forward flow. Therefore, immediately after the intake valve opening timing, no reverse flow is detected by the intake port reverse flow detection sensor 46 (NO in S108).

  Next, it is determined whether or not a specified time has elapsed from the intake valve opening timing of the # 1 cylinder (S112). This specified time is set as a delay time for the intake port backflow detection sensor 46 to reliably detect that no backflow has occurred. The specified time may be set not as a time but as a specified crank angle width.

If the specified time has not elapsed (NO in S112), the process is left as it is.
If the output Udirec of the intake port backflow detection sensor 46 does not detect backflow (NO in S108) and the specified period has elapsed (YES in S112), it is certain that no backflow has occurred. This is because there is a possibility that sudden intake of intake air from the intake port 10 into the combustion chamber 6 occurs immediately after the intake valve opening timing because the intake valve opening timing is later than TDC. It indicates that there is.

  Therefore, the intake valve opening timing is corrected to the advance side (S114). That is, as shown in Expression 1, the current intake valve opening timing advance value VT [i-1] is increased by the advance side correction amount ΔVTb to obtain a new intake valve opening timing advance value VT [i]. Set.

[Formula 1] VT [i] ← VT [i−1] + ΔVTb
The intake valve opening timing advance value VT is a control amount for the ECU 4 to adjust the actual intake valve opening timing by driving one or both of the variable valve timing mechanism 32 and the variable lift amount mechanism 34. It is. Accordingly, the ECU 4 controls the actual intake valve opening timing to the advance side using the control amount corrected to the advance side in this way.

The process is thus exited.
In the next execution cycle, even if YES is determined in both step S102 and step S104, the correction of the intake valve opening timing advance value VT at the time of the current valve opening is completed (NO in S105). Leave this process as it is.

  Thereafter, until the intake valve opening timing of the # 1 cylinder is reached again as the intake valve opening timings of the # 2, # 4, and # 3 cylinders sequentially elapse in step S104 or step S105. It is determined as NO.

  Then, if the # 1 cylinder is opened again in the cold state (YES in S104), the correction of the intake valve opening timing advance value VT at the time of the current opening is incomplete (S105). YES), the output Udirec is read (S106), and it is determined whether or not the output Udirec indicates reverse flow (S108).

  If no backflow has occurred even after the intake valve opening timing this time or the specified period of time has elapsed (YES in S112), the intake valve opening timing advance value VT is corrected to the advance side according to the above equation 1 ( S114).

  Thereafter, if the backflow does not occur even after a specified period of time has elapsed since the opening timing of the # 1 cylinder (YES in S112), the correction of the intake valve opening timing advance value VT to the advance side continues. (S114).

As a result, the opening timing of the intake valve 8 approaches TDC for all cylinders of the internal combustion engine 2.
Next, the output Udirec indicates a reverse flow from the beginning, or the processing of equation 1 (S114) is repeated, so that the intake valve opening timing advance value VT increases, and the output Udirec flows back within a specified time. (YES in S108) is considered.

  In this case, the intake valve opening timing advance value VT is corrected to the retard side (S110). That is, as shown in Equation 2, the current intake valve opening timing advance value VT [i-1] is decreased by the retard side correction amount ΔVTa to obtain a new intake valve opening timing advance value VT [i]. Set.

[Formula 2] VT [i] ← VT [i−1] −ΔVTa
Using the control amount corrected to the retard side in this way, the ECU 4 controls the actual intake valve opening timing to the retard side.

In this way, this processing is exited.
Next, in the execution cycle, even if it is determined YES in both step S102 and step S104, the correction of the intake valve opening timing advance value VT at the time of the current valve opening is completed (NO in S105). Leave this process as it is.

  Thereafter, until the intake valve opening timing of the # 1 cylinder is reached again as the intake valve opening timings of the # 2, # 4, and # 3 cylinders sequentially elapse in step S104 or step S105. It is determined as NO.

  Then, if the # 1 cylinder is opened again in the cold state (YES in S104), the correction of the intake valve opening timing advance value VT at the time of the current opening is incomplete (S105). YES), the output Udirec is read (S106), and it is determined whether or not the output Udirec indicates reverse flow (S108).

  If a backflow has occurred even at the current intake valve opening timing (YES in S108), the intake valve opening timing advance value VT is corrected to the retard side according to the above equation 2 (S110).

Thereafter, if the backflow still occurs at the valve opening timing of the # 1 cylinder (YES in S108), the correction of the intake valve opening timing advance value VT to the retard side is continued (S110).
As a result, the backflow is suppressed by delaying the intake valve opening timing for all the cylinders of the internal combustion engine 2.

  In this way, in the cold intake valve opening timing setting process (FIG. 3), when no backflow occurs, the intake valve opening timing is advanced, and when backflow occurs, the intake valve opening timing is set. Processing to delay the timing is performed.

  An example of processing according to the present embodiment is shown in FIG. This graph is a graph showing the flow rate (g / s) of the airflow per unit time flowing through the intake valve 8, and particularly in the valve opening period (period from the intake valve opening timing TO to the intake valve closing timing TC). A change in flow rate (g / s) with respect to a change in crank angle (° CA) is shown.

  FIG. 4A shows an Atkinson cycle in a state where the correction of the intake valve opening timing advance value VT by the cold intake valve opening timing setting process (FIG. 3) is not applied.

That is, since the valve opening timing is greatly retarded from the TDC, it can be seen that immediately after the valve opening timing, the rising of the flow rate is steep and rapid suction occurs.
FIG. 4B shows the state immediately before the backflow by advancing the intake valve opening timing TO from the state of FIG. 4A by the cold intake valve opening timing setting process (FIG. 3). The example (for example, intake valve opening timing TO = TDC) is shown. In this case, rapid suction does not occur immediately after the valve opening timing.

  FIG. 4C shows an example in which the valve opening timing of the intake valve 8 is further advanced to bring about a slight backflow. In this case, the intake air is sucked in after the reverse flow (Ti˜), but in this case as well, no sudden suction occurs. Since the reverse flow has occurred, the intake valve opening timing TO is retarded in the cold intake valve opening timing setting process (FIG. 3). As a result, the state of FIG. 4B is approached.

  Therefore, the intake valve opening timing TO is adjusted to the state between (B) and (C) of FIG. 4 by the processing of steps S110 and S114 of the cold intake valve opening timing setting processing (FIG. 3). become. That is, the intake valve opening timing TO is adjusted by setting the in-cylinder pressure at the intake valve opening timing TO as a target state equal to or higher than the pressure of the intake port 10.

As a result, the intake valve opening timing TO is maintained at the valve opening timing at which no sudden suction occurs and no large backflow occurs.
<Relationship between Embodiment 1 and Claims> In the configuration described above, the ECU 4 and the intake port backflow detection sensor 46 correspond to the cold valve timing setting means, and the intake port backflow detection sensor 46 serves as the intake port backflow detection means. Equivalent to. The cold intake valve opening timing setting process (FIG. 3) executed by the ECU 4 corresponds to a process as a cold valve timing setting means.
<Effects of Embodiment 1> (1) The ECU 4 adjusts the intake valve opening timing so that the above-described target state is achieved in the cold state by the cold intake valve opening timing setting process (FIG. 3). doing.

  Therefore, there is no sudden suction flow into the cylinder immediately after the intake valve 8 is opened in the cold state. That is, the intake air flow hardly flows immediately after the intake valve 8 is opened, or only a slight reverse flow state occurs. Thereafter, a flow of intake air is gradually generated and sucked into the combustion chamber 6.

  Accordingly, the liquid fuel existing on the wall surface of the intake port 10 and the back surface of the intake valve 8 during the cold state is vaporized from the surface of the liquid fuel and sucked into the combustion chamber 6 in a relatively gentle airflow. For this reason, the fuel is not sucked into the cylinder in a liquid state, and adhesion of the liquid fuel to the inner wall surface of the combustion chamber 6 can be prevented. Accordingly, local rich combustion does not occur and PM generation can be prevented.

  (2) The intake valve opening timing control by the cold intake valve opening timing setting process (FIG. 3) is performed at a timing at which the reverse flow from the combustion chamber 6, that is, the exhaust gas blowback starts to occur, particularly by the process of step S110. Thus, the intake valve opening timing is set. As a result, the backflow of the exhaust gas from the combustion chamber 6 can be prevented from becoming stronger than necessary. For this reason, PM generation can be prevented and fuel consumption can be prevented from deteriorating.

[Embodiment 2]
<Configuration of Embodiment 2> In the present embodiment, the process of FIG. 5 is executed as the cold intake valve opening timing setting process. The other configuration is the same as that of the first embodiment.

The processing in steps S202 to S208, S212, and S214 in the cold intake valve opening timing setting processing (FIG. 5) is the same as the processing in steps S102 to S108, S112, and S114 in FIG. In the cold-time intake valve opening timing setting process (FIG. 5) of the present embodiment, a process of setting correction completion without correcting the intake valve opening timing advance value VT instead of step S110 of FIG. (S210) is executed.
<Operation of Embodiment 2> Therefore, in the present embodiment, when the output period Udirec of the intake port backflow detection sensor 46 indicates no backflow (NO in S208) and the specified period has elapsed (YES in S212), As in the case of the first embodiment, the intake valve opening timing is corrected to the advance side by the above equation 1 (S214). By repeating the correction to the advance side, the intake valve 8 can be opened in a state where there is no sudden suction flow.

However, if the output Udirec of the intake port backflow detection sensor 46 indicates a backflow before the specified period elapses (NO in S208), the intake valve opening timing advance value VT is corrected to the retard side. Is completed without executing (S210).
<Relationship between Embodiment 2 and Claims> In the configuration described above, the ECU 4 and the intake port backflow detection sensor 46 correspond to the cold valve timing setting means, and the intake port backflow detection sensor 46 serves as the intake port backflow detection means. Equivalent to. The cold intake valve opening timing setting process (FIG. 5) executed by the ECU 4 corresponds to the cold valve timing setting means.
<Effects of Embodiment 2> (1) In the cold intake valve opening timing setting process (FIG. 5), the valve opening timing is advanced only when no backflow occurs immediately after the intake valve opening timing. (S214). However, when the occurrence of backflow is detected, adjustment for the valve opening timing is not executed.

  If there is an exhaust blowback immediately after the intake valve opening timing, there is no abrupt suction flow immediately after the intake valve opening timing, and therefore the valve opening timing is not corrected.

  Even in the configuration in which the intake valve opening timing is controlled only to the advance side in this way, a sudden suction flow can be prevented, so that liquid fuel can be prevented from adhering to the inner wall surface of the combustion chamber 6 when cold. Therefore, PM generation can be prevented.

Furthermore, since the correction to the advance side is actually stopped when a slight backflow occurs, it is possible to suppress deterioration of fuel consumption.
[Embodiment 3]
<Configuration of Embodiment 3> In the present embodiment, the process of FIG. 6 is executed as the cold intake valve opening timing setting process. The other configuration is the same as that of the first embodiment.

The processing of steps S302 to S312 in the cold intake valve opening timing setting processing (FIG. 6) is the same as the processing of steps S202 to S212 of FIG.
In the cold-time intake valve opening timing setting process (FIG. 6) according to the present embodiment, a newly set intake valve opening timing advance value VT [i] is set instead of step S214 in the process of FIG. ], The process of setting the advance value VTx corresponding to the target state (S314) is executed.
<Operation of Embodiment 3> In this embodiment, when the output period Udirec of the intake port backflow detection sensor 46 does not indicate backflow (NO in S308) and the specified period elapses (YES in S312), the intake valve opens. It can be determined that there is a possibility that a sudden intake flow of the intake air into the combustion chamber 6 occurs immediately after the timing.

  Based on this determination, a state in which the airflow at the intake port 10 immediately after the intake valve opening timing almost stops without suction or backflow is set as a target state, and the advance value VTx corresponding to the target state is set as a new intake air amount. The valve opening timing advance value VT [i] is set (S314). Thus, it is possible to quickly shift to a state where the intake valve 8 can be opened in a state where there is no sudden suction flow.

If the output Udirec of the intake port backflow detection sensor 46 indicates a backflow before the lapse of the specified period (NO in S308), the intake valve opening timing advance is advanced as in the second embodiment. The correction completion setting is executed without correcting the angle value VT (S310).
<Relationship between Embodiment 3 and Claims> In the configuration described above, the ECU 4 and the intake port backflow detection sensor 46 correspond to the cold valve timing setting means, and the intake port backflow detection sensor 46 serves as the intake port backflow detection means. Equivalent to. The cold intake valve opening timing setting process (FIG. 6) executed by the ECU 4 corresponds to a process as a cold valve timing setting means.
<Effects of Embodiment 3> (1) In the cold intake valve opening timing setting process (FIG. 6), the intake valve opening timing is immediately set only when no backflow occurs immediately after the intake valve opening timing. The optimum advance value VTx is set. When the occurrence of backflow is detected, adjustment to the intake valve opening timing is not executed.

  In this way, by immediately shifting the intake valve opening timing to a state where the airflow at the intake port 10 is almost stopped, it is possible to quickly prevent a sudden intake immediately after the intake valve opening timing.

Therefore, liquid fuel adhesion to the inner wall surface of the combustion chamber 6 is prevented at an early stage, and PM generation can be prevented more effectively.
Further, since the advance value VTx corresponding to the target state is set to the advance value immediately before the backflow occurs, it is possible to reliably prevent deterioration of fuel consumption.

[Embodiment 4]
<Configuration of Embodiment 4> In this embodiment, when the intake valve opening timing advance value VT is corrected in Embodiment 1, 2, or 3, output torque fluctuation of the internal combustion engine 2 occurs. An output torque fluctuation preventing process for preventing the output torque fluctuation is executed. For this purpose, the ECU 4 executes the output torque fluctuation preventing process shown in FIG. 7 together with the cold intake valve opening timing setting process (any of FIGS. 3, 5 and 6) described in the above embodiments. ing.

The other configuration is the same as that of the first embodiment.
<Operation of Embodiment 4> The characteristic operation of this embodiment will be described based on the output torque fluctuation preventing process (FIG. 7). This process is repeatedly executed at a constant crank angle period (or a constant time period).

When the output torque fluctuation preventing process (FIG. 7) is started, it is first determined whether or not the intake valve opening timing has been corrected (S402).
This correction is performed by correcting the intake valve opening timing advance value VT (any one of S110, S114, S214, and S314) in the cold intake valve opening timing setting process (any of FIGS. 3, 5, and 6). ). If this correction process is performed, the determination condition in step S402 is satisfied.

  If the determination condition in step S402 is satisfied, an output torque adjustment process for canceling the output torque fluctuation due to the correction of the intake valve opening timing advance value VT is executed (S404).

When the above-described correction of the intake valve opening timing advance value VT is made to the advance side (any of S114, S214, and S314), the output torque of the internal combustion engine 2 changes to the higher side.
Therefore, in step S404, in order to prevent such a fluctuation shock toward the higher output torque, the ignition timing is retarded, the intake air amount is decreased by the throttle valve 20, and the closing timing of the intake valve 8 is delayed. The increase in output torque is canceled by either angle correction, fuel injection amount reduction correction, or a combination thereof.

When the correction of the intake valve opening timing advance value VT described above is made on the retard side (S110), the output torque of the internal combustion engine 2 changes to the lower side.
Therefore, in step S404, in order to prevent such a fluctuation shock toward the lower output torque, the ignition timing advance correction, the intake air amount increase correction by the throttle valve 20, and the intake valve 8 closing timing advance are advanced. The decrease in output torque is offset by either angle correction, fuel injection amount increase correction, or a combination thereof.

If the correction of the intake valve opening timing advance value VT has not been made (NO in S402), the process for canceling the output torque fluctuation is not executed.
<Relationship between Embodiment 4 and Claims> In the above-described configuration, the relationship between the valve timing setting means and the intake port backflow detection means during cold is as described in the above embodiments. . The ECU 4 corresponds to torque fluctuation suppressing means, and the output torque fluctuation preventing process (FIG. 7) corresponds to processing as torque fluctuation suppressing means.
<Effects of Embodiment 4> (1) Together with the effects of any of the above-described embodiments, it is possible to prevent output torque fluctuations from occurring in the internal combustion engine 2 when the intake valve opening timing is corrected.

Accordingly, it is possible to prevent the vehicle occupant from feeling uncomfortable.
[Embodiment 5]
<Configuration of Embodiment 5> The configuration of this embodiment is as shown in FIG. The internal combustion engine 102 is provided with a variable valve timing mechanism 240 in the exhaust valve 112. Therefore, the ECU 104 adjusts the valve timing of the exhaust valve 112 as well as the valve timing of the intake valve 8 side. For this reason, a cam position sensor 138a is arranged to detect the rotational phase of the exhaust camshaft 138. The other structure is as described in FIG. Accordingly, the same components are denoted by the same reference numerals.

As for the process executed by the ECU 104, any one of the first to fourth embodiments is executed.
When the configuration of FIG. 8 is applied to the fourth embodiment, in step S404 of FIG. 7, the fourth embodiment is described by adjusting the valve timing of the exhaust valve 112 or together with this adjustment. The output torque fluctuation may be prevented by combining other processes.
<Operation of the Fifth Embodiment> In the present embodiment, the intake valve opening timing advance value VT at which the reverse flow starts to occur differs depending on the valve timing of the exhaust valve 112.

  Even in this case, when the processing of FIG. 3 or FIG. 5 is used, the processing automatically proceeds to the appropriate intake valve opening timing advance value VT by the processing of step S110, S114 or step S214. Become.

When the processing of FIG. 6 is used, in step S314, an appropriate advance angle value VTx is first calculated in accordance with the exhaust valve closing timing, and this calculated advance angle value VTx is calculated. The valve timing advance value VT is set.
<Relationship between Embodiment 5 and Claims> The relationship is the same as that described in each of the above embodiments.
<Effects of Embodiment 5> (1) The internal combustion engine 102 in which the valve timing of the exhaust valve 112 is changed in this way produces the same effects as those described in the above embodiments.

[Embodiment 6]
<Configuration of Embodiment 6> The configuration of this embodiment is as shown in FIG.
However, instead of the cold intake valve opening timing setting process (any of FIGS. 3, 5 and 6), any one of the cold exhaust valve closing timing setting processes shown in FIGS.

  When the cold exhaust valve closing timing setting process in FIG. 9 is executed, steps S502, S504, S506, S508, and S512 are the steps of the cold intake valve opening timing setting process (FIG. 3). This is the same as S102, S104, S106, S108, and S112.

  The differences are as follows. That is, instead of determining whether or not the correction of the intake valve opening timing advance value VT at the time of the current valve opening is incomplete (FIG. 3: S105), the exhaust valve closing at the time of the current valve opening is closed. It is determined whether or not the correction of the valve timing advance value VTe is incomplete (S505).

  Instead of the process of correcting the intake valve opening timing advance value VT to the advance side (FIG. 3: S114), the process of correcting the exhaust valve closing timing advance value VTe to the retard side as shown in Equation 3 ( S514) is executed.

[Formula 3] VT [i] ← VT [i−1] −ΔVTeb
That is, Formula 3 is brought close to the opening timing of the intake valve 8 by delaying the closing timing of the exhaust valve 112. This prevents the combustion chamber 6 from being in a negative pressure state even if the opening timing of the intake valve 8 is later than TDC.

  Further, instead of the process of correcting the intake valve opening timing advance value VT to the retard side (FIG. 3: S110), the exhaust valve closing timing advance value VTe is corrected to the advance side as shown in Expression 4. A process (S510) is performed.

[Formula 4] VTe [i] ← VTe [i−1] + ΔVTea
That is, Expression 4 makes the closing timing of the exhaust valve 112 earlier, so that the exhaust valve closing timing is too retarded by Expression 3, and exhaust from other cylinders flows into the combustion chamber 6, and the combustion chamber 6 This is a process for reducing the backflow by increasing the closing timing of the exhaust valve 112 when a backflow from the engine to the intake system occurs.

  When the cold exhaust valve closing timing setting process of FIG. 10 is executed, the steps S602, S604, S606, S608, and S612 are the steps of the cold intake valve opening timing setting process (FIG. 5). This is the same as S202, S204, S206, S208, and S212.

  The differences are as follows. That is, instead of determining whether or not the correction of the intake valve opening timing advance value VT at the time of this valve opening is incomplete (FIG. 5: S205), the exhaust valve closing timing advance at the time of this valve opening is advanced. It is determined whether or not the correction of the angle value VTe is incomplete (S605).

  In place of the process of completing the setting process without correcting the intake valve opening timing advance value VT (FIG. 5: S210), the process of setting the correction completion without correcting the exhaust valve closing timing advance value VTe (S610). ).

  Then, instead of the process of correcting the intake valve opening timing advance value VT to the advance side (FIG. 5: S214), the exhaust valve closing timing advance value VTe is corrected to the retard side as shown in Equation 3 above. The process (S614) to perform is performed.

  That is, when no backflow occurs, the exhaust valve closing timing is delayed to approach the opening timing of the intake valve 8, so that even if the opening timing of the intake valve 8 is later than TDC, the combustion chamber 6 The inside does not become a negative pressure state. In the case of backflow, the exhaust valve closing timing remains unchanged.

  When the cold exhaust valve closing timing setting process in FIG. 11 is executed, steps S702 to S712 are the same as steps S602 to S612 in FIG. The difference is that instead of the process of correcting the exhaust valve closing timing advance value VTe to the retard side (S614), the advance value VTex corresponding to the target state is set to the exhaust valve closing timing advance value VTe. It is a point which performs the process (S714) to perform.

In other words, the advance value VTex that can achieve an airflow state in which no reverse flow or a sudden suction flow occurs at the intake valve opening timing is immediately set to the exhaust valve closing timing advance value VTe.
<Operation of Embodiment 6> In this embodiment, the closing timing of the exhaust valve 112 is retarded when there is a possibility that intake air may suddenly blow into the combustion chamber 6 from the intake valve 8.

Due to the delay of the exhaust valve closing timing, the exhaust gas existing in the exhaust system returns into the combustion chamber 6 when the piston 26 descends after TDC. As a result, even if the intake valve opening timing is later than TDC, the pressure in the combustion chamber 6 immediately after the intake valve opening timing does not become negative, and a sudden intake of intake air does not occur.
<Relationship between Embodiment 6 and Claims> In the configuration described above, the ECU 104 and the intake port backflow detection sensor 46 correspond to the cold valve timing setting means, and the intake port backflow detection sensor 46 serves as the intake port backflow detection means. Equivalent to. The cold exhaust valve closing timing setting process (FIGS. 9 to 11) executed by the ECU 104 corresponds to a cold valve timing setting means.

Furthermore, the same processing as that in FIG. 7 described in the fourth embodiment may be added as the output torque fluctuation preventing processing at the time of correcting the exhaust valve closing timing. In this case, the ECU 104 corresponds to torque fluctuation suppressing means, and the output torque fluctuation preventing process corresponds to processing as torque fluctuation suppressing means.
<Effects of Embodiment 6> (1) As described above, even in the case of the internal combustion engine 102 that is provided with the variable valve timing mechanism 240 and is also subject to adjustment of the valve timing of the exhaust valve 112, Similar to the effects described above, the liquid fuel can be prevented from adhering to the inner wall surface of the combustion chamber 6, thereby preventing the generation of PM.

[Other embodiments]
A temperature sensor may be used as the intake port backflow detection sensor 46 shown in FIGS. When there is no backflow from the combustion chamber 6 to the intake port 10, as shown in FIG. 12A, there is almost no temperature change at the intake port 10, but when there is a backflow, FIG. As shown in the figure, heat is transferred from the exhaust gas, and a temperature change (peak Pt) occurs.

Therefore, when a temperature sensor is used as the intake port backflow detection sensor 46, the presence or absence of backflow can be detected based on the presence or absence of such a peak Pt.
This is the same when the CO2 sensor that detects the CO2 concentration is used as the intake port backflow detection sensor 46, and it can be determined that a backflow has occurred due to the peak of the CO2 concentration.

  In the fifth embodiment, the PM prevention processing is performed by adjusting the intake valve opening timing. However, by combining the processing of the sixth embodiment, the adjustment of the intake valve opening timing and the adjustment of the exhaust valve closing timing are performed. In both cases, PM prevention processing may be executed.

  As a configuration of the variable valve mechanism, the lift amount variable mechanism 34 shown in FIG. 1 may be omitted. That is, only the variable valve timing mechanism 32 of the intake valve 8 may be used, or only the combination of the variable valve timing mechanism 32 of the intake valve 8 and the variable valve timing mechanism 240 of the exhaust valve 112 as shown in FIG.

  In each of the above embodiments, the intake port backflow detection sensor 46 is provided in the intake port of the # 1 cylinder. However, the intake port backflow detection sensor is provided in the intake ports of other cylinders or in all intake ports. 46 may be arranged. As a result, the backflow state can be detected when each cylinder is opened. Therefore, since the intake valve opening timing advance value VT and the exhaust valve closing timing advance value VTe can be corrected at a high frequency, liquid fuel adhesion to the inner wall surface of the combustion chamber can be prevented quickly and reliably. Generation prevention can be further enhanced.

  DESCRIPTION OF SYMBOLS 2 ... Internal combustion engine, 4 ... ECU, 6 ... Combustion chamber, 8 ... Intake valve, 10 ... Intake port, 12 ... Exhaust valve, 14 ... Exhaust port, 16 ... Fuel injection valve, 18 ... Intake manifold, 18a ... Surge tank, 18b ... Branch pipe, 20 ... Throttle valve, 20a ... Motor, 20b ... Throttle opening sensor, 22 ... Intake amount sensor, 24 ... Spark plug, 26 ... Piston, 28 ... Crankshaft, 30 ... Intake camshaft, 30a ... Intake Cam 30b ... Cam position sensor 32 ... Valve timing variable mechanism 34 ... Lift amount variable mechanism 36 ... Accelerator pedal 36a ... Accelerator operation amount sensor 38 ... Exhaust camshaft 42 ... Engine speed sensor 44 ... Cooling Water temperature sensor 46 ... Intake port backflow detection sensor 102 ... Internal combustion engine 104 ... ECU 112 ... Exhaust bar 138 ... Exhaust camshaft, 138a ... Cam position sensor, 240 ... Variable valve timing mechanism, Pt ... Peak, TC ... Intake valve closing timing, TO ... Intake valve opening timing, VT ... Intake valve opening timing advance value.

Claims (7)

In an internal combustion engine that injects fuel into an intake port, an internal combustion engine valve timing control device that executes control for retarding an intake valve opening timing from TDC in accordance with an operating state of the internal combustion engine,
When the internal combustion engine is cold, the target state is a state where the cylinder pressure at the intake valve opening timing is equal to or higher than the intake port pressure, and either or both of the intake valve opening timing and the exhaust valve closing timing are set. An internal combustion engine valve timing control device comprising a cold valve timing setting means for adjusting. 2. The internal combustion engine valve timing control apparatus according to claim 1, wherein the cold valve timing setting means adjusts the intake valve opening timing in a direction approaching the target state when the internal combustion engine is cold. Engine valve timing control device. 3. The internal combustion engine valve timing control device according to claim 2, wherein the cold time valve timing setting means includes intake port reverse flow detection means for detecting a reverse flow state of the air flow at the intake port, and the intake valve is cold when the internal combustion engine is cold. Immediately after the valve opening timing, when the intake port backflow detection means does not detect the occurrence of backflow, the intake valve opening timing is advanced, and when the occurrence of backflow is detected, the intake valve opening timing is retarded. An internal combustion engine valve timing control device. 3. The internal combustion engine valve timing control device according to claim 2, wherein the cold time valve timing setting means includes intake port reverse flow detection means for detecting a reverse flow state of the air flow at the intake port, and the intake valve is cold when the internal combustion engine is cold. Immediately after the valve opening timing, if the intake port backflow detection means does not detect the occurrence of backflow, the intake valve opening timing is advanced, and if the occurrence of backflow is detected, the adjustment to the intake valve opening timing is not executed. An internal combustion engine valve timing control device. 3. The internal combustion engine valve timing control device according to claim 2, wherein the cold time valve timing setting means includes intake port reverse flow detection means for detecting a reverse flow state of the air flow at the intake port, and the intake valve is cold when the internal combustion engine is cold. If the intake port backflow detection means does not detect the occurrence of backflow immediately after the valve opening timing, the intake valve opening timing is set to an advance value corresponding to the target state, and if the occurrence of backflow is detected, the intake valve opens. An internal combustion engine valve timing control device characterized in that no adjustment to the valve timing is executed. The internal combustion engine valve timing control device according to any one of claims 1 to 5, wherein the control for delaying the intake valve opening timing from TDC is executed as an Atkinson cycle. Valve timing control device. In the internal combustion engine valve timing control device according to any one of claims 1 to 6,
Torque fluctuation suppressing means for suppressing output torque fluctuation of the internal combustion engine that occurs when the cold valve timing setting means adjusts one or both of the intake valve opening timing and the exhaust valve closing timing to control to the target state An internal combustion engine valve timing control device comprising:

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