JP4258453B2 - Intake control device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake air control device for an internal combustion engine that can variably control the valve timing of an intake valve by a hydraulic variable valve timing mechanism, and more particularly, at the time of starting an internal combustion engine in which the variable valve timing mechanism cannot operate effectively due to insufficient hydraulic pressure TECHNICAL FIELD OF THE INVENTION

  Conventionally, a hydraulic variable valve timing mechanism that variably controls the valve timing of the intake valve by changing the phase angle of the camshaft with respect to the crankshaft is known. FIG. 6 is a diagram showing a schematic configuration of a hydraulic system of a conventional variable valve timing mechanism. The variable valve timing mechanism includes a hydraulic actuator 50 for changing the phase angle of the cam shaft (intake side cam shaft) with respect to the crank shaft. The hydraulic actuator 50 includes a housing 52 that rotates in synchronization with the crankshaft, and a rotor 54 that is disposed in the housing 52 and rotates in synchronization with the camshaft. Oil chambers 56 and 58 are formed inside the housing 52, and the oil chambers 56 and 58 are divided into a first oil chamber 56 and a second oil chamber 58 by the rotor 54.

  The hydraulic actuator 50 operates when hydraulic oil is supplied to the oil chambers 56 and 58 and the rotation angle of the rotor 54 with respect to the housing 52 changes. When hydraulic oil is supplied to the first oil chamber 56, the hydraulic actuator 50 operates so as to change the phase angle of the camshaft relative to the crankshaft to the advance side, and the hydraulic oil is supplied to the second oil chamber 58. Sometimes it operates to change the phase angle of the camshaft relative to the crankshaft to the retard side. At this time, the internal hydraulic oil is pushed out from the oil chamber on the side where the hydraulic oil is not supplied as the hydraulic chamber on the side where the hydraulic oil is supplied, and the pushed hydraulic oil is collected in the oil tank 64. It is like that.

  The hydraulic oil supplied to the hydraulic actuator 50 is pumped from an oil pump 60 driven by the internal combustion engine 70. An oil control valve 62 is provided between the oil pump 60 and the hydraulic actuator 50. The oil control valve 62 is a directional switching valve that switches between a supply destination of the hydraulic oil and a recovery destination of the hydraulic oil between the first oil chamber 56 and the second oil chamber 58, and at the same time, supplies the hydraulic oil by controlling its opening degree. It is also a flow control valve that can adjust the amount. The amount of advance of the phase angle of the camshaft relative to the crankshaft can be controlled by the amount of hydraulic oil supplied to the first oil chamber 56, and similarly, the amount of retard is supplied of hydraulic oil to the second oil chamber 58. Can be controlled by quantity.

  When the internal combustion engine 70 is stopped, the variable valve timing mechanism is controlled to stop at either the most advanced position or the most retarded position, and at the next start, either the most advanced position or the most retarded position. It starts from the position. However, since the oil pump 60 that supplies the hydraulic oil to the hydraulic actuator 50 receives the driving force supplied from the internal combustion engine 70 and generates the hydraulic pressure, the oil pump 60 is driven to increase the hydraulic pressure when the internal combustion engine 70 is started. In the meantime, the variable valve timing mechanism cannot achieve the required operation due to insufficient hydraulic pressure. For this reason, the variable valve timing mechanism cannot be operated until the hydraulic pressure rises, and the valve timing of the intake valve remains the most advanced angle or the most retarded angle.

  The valve timing of the intake valve has a suitable timing according to the operating state of the internal combustion engine, and also has a suitable timing when starting the internal combustion engine. If the actual valve timing is greatly deviated from this preferred timing, the startability of the internal combustion engine is reduced. For example, when the valve timing is advanced most at the start of the internal combustion engine, the valve overlap period becomes longer and the internal EGR amount increases, so that the startability is lowered due to deterioration of combustion. Also, if the valve timing is retarded at the time of starting the internal combustion engine, the closing timing of the intake valve greatly exceeds the intake bottom dead center, so that the air-fuel mixture blowback from the combustion chamber to the intake passage increases. Therefore, the startability is reduced due to insufficient torque due to a decrease in filling efficiency.

In order to solve this problem, the variable valve timing mechanism described in Patent Document 1 includes a lock pin in the rotor and a locking hole in the housing as positioning means at the time of starting. When the internal combustion engine is started, the lock pin is locked in the locking hole, so that the rotational position of the rotor with respect to the housing is positioned in an intermediate region excluding the most advanced position and the most retarded angle position. A desired valve timing suitable for starting is obtained by adjusting the phase angle.
JP-A-11-182214 JP 2000-170507 A JP 2000-234533 A JP 2002-161721 A

  However, the technique described in Patent Document 1 requires a complicated mechanism for reliably locking the lock pin in the locking hole. Further, the valve timing excellent in startability varies depending on the state of the internal combustion engine at the time of start (temperature of the internal combustion engine, etc.), but in the technique described in Patent Document 1, the valve timing at the time of start is determined by the lock pin and the locking hole. It is fixed at the timing determined by the position. For this reason, the optimal valve timing according to the starting state of the internal combustion engine is not always realized.

  The present invention has been made to solve the above-described problems, and can achieve intake control suitable for starting an internal combustion engine without using a complicated mechanism, and can improve the startability of the internal combustion engine. An object of the present invention is to provide an intake control device for an internal combustion engine.

In order to achieve the above object, a first invention is an intake control device for an internal combustion engine,
A hydraulic variable valve timing mechanism that variably controls the valve timing of the intake valve and operates from a position where the valve timing of the intake valve is most retarded when starting the internal combustion engine;
An intake control valve provided in the intake passage of each cylinder for opening and closing the intake passage;
Control means for controlling the end timing of the effective intake period by the closing timing of the intake control valve by closing the intake control valve at the advance side with respect to the closing timing of the intake valve when starting the internal combustion engine When,
It is characterized by having.

  In a second aspect based on the first aspect, the control means acquires a parameter related to the temperature of the internal combustion engine when starting the internal combustion engine, and closes the intake control valve according to the value of the parameter. It is characterized by controlling timing.

A third invention is an intake control device for an internal combustion engine in order to achieve the above object,
A hydraulic variable valve timing mechanism that variably controls the valve timing of the intake valve and operates from a position where the valve timing of the intake valve is advanced most at the time of starting the internal combustion engine;
An intake control valve provided in the intake passage of each cylinder for opening and closing the intake passage;
Control means for controlling the start timing of the effective intake period according to the opening timing of the intake control valve by opening the intake control valve at a retarded angle side relative to the opening timing of the intake valve when starting the internal combustion engine When,
It is characterized by having.

  In a fourth aspect based on the third aspect, the control means acquires a parameter related to the temperature of the internal combustion engine when the internal combustion engine is started, and opens the intake control valve according to the value of the parameter. It is characterized by controlling timing.

  According to a fifth invention, in the third or fourth invention, the control means opens the intake control valve after intake top dead center.

A sixth invention is an intake control device for an internal combustion engine in order to achieve the above object,
A hydraulic variable valve timing mechanism that variably controls the valve timing of the intake valve;
An intake control valve provided in the intake passage of each cylinder for opening and closing the intake passage;
Determining means for determining a stop position of the variable valve timing mechanism;
Control means for controlling the start timing or end timing of the effective intake period by controlling the opening timing or closing timing of the intake control valve according to the determination result of the determination means,
When the internal combustion engine is started, and the determination means determines that the variable valve timing mechanism is stopped at a position where the valve timing of the intake valve is most retarded, the intake valve By closing the intake control valve on the advance side of the valve closing timing, the end timing of the effective intake period is controlled by the valve closing timing of the intake control valve,
When it is determined by the determination means that the variable valve timing mechanism is stopped at a position where the valve timing of the intake valve is advanced most, the variable valve timing mechanism is more retarded than the valve opening timing of the intake valve. By opening the intake control valve, the start timing of the effective intake period is controlled by the opening timing of the intake control valve.

  When the hydraulic variable valve timing mechanism operates from the position where the valve timing of the intake valve is most retarded, until the hydraulic pressure rises due to the start of the internal combustion engine and the variable valve timing mechanism becomes operable, the intake valve Since the valve closing timing exceeds the intake bottom dead center, the air-fuel mixture blowback from the combustion chamber to the intake passage increases. However, according to the first aspect of the invention, the intake control valve is closed on the advance side with respect to the closing timing of the intake valve, and the effective intake period, that is, the intake passage, the combustion chamber, By controlling the end timing of the period during which the engine is substantially in communication, it is possible to suppress the blowback from the combustion chamber to the intake passage and to reliably output the necessary torque, and to improve the startability of the internal combustion engine Can do.

  Note that, as the temperature of the internal combustion engine is higher, the internal friction becomes smaller and the generated fuel becomes more atomized, so that the generated torque becomes larger. Accordingly, if the intake air amount is set in accordance with the low engine temperature, the generated torque becomes excessive and the torque shock occurs when the engine temperature is high. Conversely, if the intake air amount is set in accordance with the high engine temperature, the generated torque is insufficient and the startability is impaired when the engine temperature is low. However, according to the second aspect of the invention, the intake air amount can be controlled according to the engine temperature by the closing timing of the intake control valve, so that a good start can be realized regardless of the engine temperature.

  Further, when the hydraulic variable valve timing mechanism operates from a position where the valve timing of the intake valve is advanced, the valve is not operated until the hydraulic pressure rises due to the start of the internal combustion engine and the variable valve timing mechanism becomes operable. As the overlap period becomes longer, the amount of internal EGR becomes excessive and the combustion deteriorates. However, according to the third invention, by opening the intake control valve on the retard side with respect to the opening timing of the intake valve, and controlling the start timing of the effective intake period by the opening timing of the intake control valve, The valve overlap period can be shortened to suppress the internal EGR amount, and the startability of the internal combustion engine can be improved by improving the combustion.

  Note that the combustibility at the start of the internal combustion engine varies depending on the temperature state of the internal combustion engine. According to the fourth aspect of the invention, the internal EGR amount can be controlled according to the engine temperature according to the opening timing of the intake control valve, so that a good start can be realized regardless of the engine temperature.

  The startability of the internal combustion engine improves as the mixing of fuel and fresh air becomes better. According to the fifth aspect of the invention, since the intake control valve is opened after the intake top dead center, intake is started in a state where the combustion chamber is at a negative pressure, and the inflow speed of the mixture into the combustion chamber is increased. To rise. As a result, mixing of fuel and fresh air is promoted, combustion is improved, and startability of the internal combustion engine is further improved.

  According to the sixth aspect of the invention, even when the stop position of the variable valve timing mechanism when the internal combustion engine is stopped is not determined to be either the most advanced angle position or the most retarded angle position, the variable valve timing mechanism is variable when the internal combustion engine is started. A stop position of the valve timing mechanism is determined. When the variable valve timing mechanism is stopped at the most retarded position, the intake control valve is closed on the advance side of the intake valve closing timing, and effective intake is determined by the intake control valve closing timing. By controlling the end timing of the period, the blowback of the air-fuel mixture from the combustion chamber to the intake passage is suppressed. Further, when the variable valve timing mechanism is stopped at the most advanced angle position, the intake control valve is opened on the retard side with respect to the opening timing of the intake valve, and the effective intake is determined by the opening timing of the intake control valve. By controlling the start timing of the period, the internal EGR amount is optimized by adjusting the valve overlap period. Thereby, a favorable start can be realized regardless of the stop position of the variable valve timing mechanism.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram for explaining the configuration of an internal combustion engine system to which an intake air control apparatus according to an embodiment of the present invention is applied. The internal combustion engine 2 according to the present embodiment is a spark ignition type four-stroke engine, and has a plurality of cylinders (not shown). A crank angle sensor 32 that outputs a signal at a predetermined crank angle position is attached in the vicinity of the crankshaft 14 of the internal combustion engine 2. A water temperature sensor 38 for measuring the coolant temperature is attached to a water jacket (not shown).

  An intake port 4a and an exhaust port 6a are connected to the combustion chamber 12 of each cylinder. An intake valve 8 for controlling the communication state is provided at a connection portion between the combustion chamber 12 and the intake port 4a, and an exhaust valve 10 for controlling the communication state is provided at a connection portion between the combustion chamber 12 and the exhaust port 6a. It has been. The intake valve 8 and the exhaust valve 10 both open and close in response to input of driving force from a camshaft driven by the crankshaft 14. In particular, the camshaft of the intake valve 8 is provided with a hydraulic variable valve timing mechanism (VVT) 26 that can variably control the valve timing of the intake valve 8 by hydraulic pressure. As the structure of the variable valve timing mechanism 26, for example, the structure shown in FIG. 6 can be used. Further, the variable valve timing mechanism 26 according to the present embodiment is provided with a stop position sensor 36 for detecting the stop position (the stop position of the rotor with respect to the housing).

  The intake pipe 4 is connected to the intake port 4a, and the exhaust pipe 6 is connected to the exhaust port 6a. The intake pipe 4 forms an intake passage together with the intake port 4a. An air cleaner 16 is provided at the upstream end of the intake pipe 4, and an air flow meter 34 for measuring an intake air flow rate (fresh air flow rate) is disposed immediately downstream of the air cleaner 16. Further, an electronically controlled throttle valve 20 is disposed downstream of the air flow meter 34. A surge tank 18 having a function such as smoothing of pressure fluctuation is formed downstream of the throttle valve 20 of the intake pipe 4. The intake pipe 4 is branched into a plurality of intake manifolds 4b for distributing intake air to the combustion chambers 12 of each cylinder with the surge tank 18 as a branch point. Each intake manifold 4b has a corresponding intake port. 4a. An intake control valve 22 and a fuel injection valve 24 are attached to each intake port 4a in order from the upstream side.

  The intake control valve 22 is a valve that blocks and opens the flow of intake air in the intake port 4a, and is opened and closed by an electromagnetically driven actuator. The intake control valve 22 according to this embodiment is selectively driven to one of an open position where the intake port 4a is fully opened and a closed position where the intake port 4a is fully closed. The actuator of the intake control valve 22 performs an operation of returning the intake control valve 22 from the open position to the closed position and then returning to the open position, or driving from the closed position to the open position and then returning to the closed position at the crank angle. It can be performed within 720 ° CA. By operating the intake control valve 22 during the operation of the internal combustion engine 2, the intake period of the air-fuel mixture from the intake port 4 a determined by the valve timing of the intake valve 8 into the combustion chamber 12 can be adjusted. When the intake control valve 22 is open, the air-fuel mixture is drawn into the combustion chamber 12 according to the valve timing of the intake valve 8, but when the intake control valve 22 is closed, the intake valve 8 No intake is performed regardless of the valve timing. That is, the period during which both the intake valve 8 and the intake control valve 22 are open is the period during which the intake port 4a and the combustion chamber 12 are substantially in communication, that is, the effective intake period.

  As described above, the internal combustion engine 2 according to the present embodiment includes the intake control valve 22 together with the variable valve timing mechanism 26 that controls the valve timing of the intake valve 8 as means for controlling the effective intake period. Accordingly, when the internal combustion engine 2 is started, the effective intake period can be controlled by the intake control valve 22 in a situation where the variable valve timing mechanism 26 cannot be effectively operated due to insufficient hydraulic pressure. Note that the control of the effective intake period at the time of starting is realized by controlling the intake control valve 22 by an ECU (Electronic Control Unit) 30. The ECU 30 is a control device for comprehensively controlling the operation of the internal combustion engine 2, and receives detection signals from various sensors such as the crank angle sensor 32, the air flow meter 34, the rotational position sensor 36, and the water temperature sensor 38 described above. At the same time, drive signals are supplied to various devices such as the throttle valve 20, the intake control valve 22, the fuel injection valve 24, and the variable valve timing mechanism 26 in accordance with a predetermined control program.

  2 and 3 are explanatory diagrams showing the operation of the intake control valve 22 when the internal combustion engine 2 is started. In FIGS. 2 and 3, the change in the opening degree of the intake control valve 22 with respect to the crank angle is shown together with the change in the lift amount of the intake valve 8. When the internal combustion engine 2 is stopped, the variable valve timing mechanism 26 is controlled by the ECU 30 to stop at either the most advanced position or the most retarded position. Therefore, the valve timing of the intake valve 8 at the time of starting is the most retarded as shown in FIG. 2 or the most advanced as shown in FIG. The stop position of the variable valve timing mechanism 26 can be determined by a detection signal from the stop position sensor 36.

  When the variable valve timing mechanism 26 is stopped at the most retarded position when the internal combustion engine 2 is started, that is, when the valve timing of the intake valve 8 is most retarded as shown in FIG. The closing timing of the valve 8 greatly exceeds the intake BDC (bottom dead center) and is located in the middle of the compression stroke. This is because the cam profile of the cam shaft that drives the intake valve 8 is designed so as to obtain ideal intake characteristics at high rotation and high load. Even if it is attempted to start the internal combustion engine 2 at such valve closing timing, since the air-fuel mixture blowback from the combustion chamber 12 to the intake port 4a is large, the charging efficiency is lowered, and the engine cannot be started well due to insufficient torque. there is a possibility.

  Therefore, when the ECU 30 determines from the detection signal from the stop position sensor 36 that the variable valve timing mechanism 26 is stopped at the most retarded position, the intake air is advanced on the more advanced side than the closing timing of the intake valve 8. The control valve 22 is closed. Preferably, the closing timing of the intake control valve 22 is set near the intake BDC. As a result, the communication between the intake port 4a and the combustion chamber 12 is blocked in the vicinity of the intake BDC, and the air-fuel mixture blowback from the combustion chamber 12 to the intake port 4a is suppressed, so that the startability of the internal combustion engine 2 is improved. improves. In this case, the effective intake period is from the opening timing of the intake valve 8 to the closing timing of the intake control valve 22. Further, the hatched portion in FIG. 2 corresponds to the substantial lift amount of the intake valve 8 corrected by the opening degree of the intake control valve 22. The valve opening timing of the intake control valve 22 may be earlier than the valve opening timing of the intake valve 8 and later than the valve closing timing of the intake valve 8 in the previous cycle.

  In this case, the ECU 30 adjusts the closing timing of the intake control valve 22 according to the water temperature of the internal combustion engine 2 detected by the water temperature sensor 38. Specifically, the higher the water temperature, the farther the valve closing timing is set from the intake BDC (which may be the advance side or the retard side), and the intake amount of the air-fuel mixture into the combustion chamber 12 is reduced. If the valve closing timing is set to an advance side with respect to the intake BDC, the intake amount of the air-fuel mixture decreases as the communication between the intake port 4a and the combustion chamber 12 is quickly closed. If the valve closing timing is set to the retard side with respect to the intake BDC, the intake amount of the air-fuel mixture is also reduced by the blowback to the intake port 4a. The higher the temperature of the internal combustion engine 2, the smaller the internal friction and the better the atomization of the injected fuel, so the generated torque increases. For this reason, if the closing timing of the intake control valve 22 at the time of high temperature is set to be the same as that at the time of low temperature, the generated torque becomes excessive and torque shock occurs. Therefore, by controlling the closing timing of the intake control valve 22 so as to reduce the intake amount of the air-fuel mixture as the engine temperature represented by the water temperature is higher as described above, it is possible to always perform a good start regardless of the engine temperature. Can be realized.

  On the other hand, when the variable valve timing mechanism 26 is stopped at the most advanced angle position when the internal combustion engine 2 is started, that is, when the valve timing of the intake valve 8 is most advanced as shown in FIG. The valve opening timing of the intake valve 8 greatly exceeds the intake TDC (top dead center) and is located in the middle of the exhaust stroke. This is because the cam profile of the intake cam that drives the intake valve 8 is designed so as to obtain ideal intake characteristics at high rotation and high load. Even if it is attempted to start the internal combustion engine 2 at such valve opening timing, there is a possibility that the internal EGR amount increases due to a longer valve overlap period with the exhaust valve 10 and cannot be started successfully due to deterioration of combustion. There is.

  Therefore, if the ECU 30 determines from the detection signal from the stop position sensor 36 that the variable valve timing mechanism 26 is stopped at the most advanced angle position, the intake air is retarded from the valve opening timing of the intake valve 8. The control valve 22 is opened. As a result, the communication between the intake port 4a and the combustion chamber 12 is blocked until the intake control valve 22 is opened even after the intake valve 8 is opened, and combustion is improved by suppressing the internal EGR amount. The startability of the internal combustion engine 2 is improved. In this case, the effective intake period is from the opening timing of the intake control valve 22 to the closing timing of the intake valve 8. Further, the hatched portion in FIG. 3 corresponds to the substantial lift amount of the intake valve 8 corrected by the opening degree of the intake control valve 22. The closing timing of the intake control valve 22 only needs to be later than the closing timing of the intake valve 8 and earlier than the opening timing of the intake valve 8 in the next cycle.

  The opening timing of the intake control valve 22 is preferably set to about 10 to 30 ° CA after intake TDC. As long as the opening timing of the intake control valve 22 is retarded from the opening timing of the intake valve 8, the effect of suppressing the internal EGR amount can be obtained even before the intake TDC. However, after the intake TDC as described above, the intake control valve 22 is opened particularly at 10 to 30 ° CA, whereby a further effect that contributes to an improvement in startability can be obtained. Since the intake control valve 22 is closed until after the intake TDC, the pressure in the combustion chamber 12 becomes negative. By starting intake in this state, the inflow speed of the air-fuel mixture into the combustion chamber 12 increases. The fuel and fresh air mixing is promoted to further improve the combustion.

  In this case, the ECU 30 adjusts the opening timing of the intake control valve 22 in accordance with the water temperature of the internal combustion engine 2 detected by the water temperature sensor 38. Since the combustibility of the internal combustion engine 2 at the time of start varies depending on the temperature state of the internal combustion engine 2, the internal EGR amount is controlled by adjusting the valve opening timing of the intake control valve 22 according to the engine temperature represented by the water temperature. Therefore, it is possible to always achieve a good start regardless of the engine temperature.

  Next, a process executed by the ECU 30 in order to realize the operation of the intake control valve 22 will be described. The processing by the ECU 30 is broadly divided into processing when IG (ignition) is turned on and processing until the variable valve timing mechanism 26 becomes operable after the IG is turned on.

  First, when the IG is turned on by a driver's key operation to start the internal combustion engine 2, the ECU 30 executes a routine shown in FIG. FIG. 4 is a flowchart of a routine executed by the ECU 30 when the IG is turned on. In the first step 100 of this routine, after the internal combustion engine 2 is started, the amount of air necessary to reach the target rotational speed (here, the target idle rotational speed) is calculated based on information such as the water temperature. Next, the stop position of the variable valve timing mechanism 26 is determined from the detection signal from the stop position sensor 36 (step 102).

  The on-off valve timing of the intake control valve 22 is experimentally obtained in advance using parameters such as the stop position of the variable valve timing mechanism 26, the required air amount, and the water temperature, and is stored in a map. In step 104, the required air amount calculated in step 100, the stop position of the variable valve timing mechanism 26 determined in step 102, etc. are calculated from the map according to the values of the parameters.

  In the next step 106, the ECU 30 operates the intake control valve 22 to an initial position corresponding to the stop position of the variable valve timing mechanism 26 determined in step 102. When the variable valve timing mechanism 26 is stopped at the most retarded position, the intake control valve 22 needs to be opened at the opening timing of the intake valve 8 as shown in FIG. The initial position of the valve 22 is the fully open position. When the variable valve timing mechanism 26 is stopped at the most advanced position, the intake control valve 22 needs to be closed at the opening timing of the intake valve 8 as shown in FIG. The initial position of the valve 22 is a fully closed position. At this stage, since the crankshaft 14 is not rotating, the cylinder discrimination performed based on the signal from the crank angle sensor 32 is not completed. For this reason, the ECU 30 operates the intake control valves 22 of all the cylinders to the initial position.

  After the cranking is started by turning on the IG, the ECU 30 executes a routine shown in FIG. FIG. 5 is a flowchart of a routine executed by the ECU 30 after the IG is turned on until the variable valve timing mechanism 26 becomes operable. This routine is executed for each predetermined crank angle. First, in step 110, the ECU 30 determines whether or not the variable valve timing mechanism 26 is operable. For example, the variable valve timing mechanism 26 measures the hydraulic pressure supplied from the oil pump to the hydraulic actuator, and determines that the variable valve timing mechanism 26 is operable if the hydraulic pressure is within a predetermined operating range.

  Until the variable valve timing mechanism 26 becomes operable in the determination in step 110, the ECU 30 executes the processes in and after step 112. In step 112, it is determined whether or not the opening timing of the intake control valve 22 has arrived. When the valve opening timing arrives, the intake control valve 22 is opened (step 114). If it is not the valve opening timing, it is determined whether or not the valve closing timing of the intake control valve 22 has arrived (step 116). When it is determined that the valve closing timing has arrived, the intake control valve 22 is closed (step 118).

  When the current crank angle does not correspond to the valve opening timing or the valve closing timing, the ECU 30 determines whether or not a predetermined calculation timing has arrived (step 120). The calculation timing does not need to be related to the operation timing of the intake control valve 22, and for example, the exhaust BDC can be set as the calculation timing. At the calculation timing, the required air amount corresponding to the target rotational speed calculated when the IG is turned on is recalculated (step 122), and the opening / closing valve timing of the intake control valve 22 is also recalculated based on the recalculated required air amount. (Step 124). The next valve opening timing arrival determination (step 112) and the valve closing timing arrival determination (step 116) are performed based on the recalculated opening / closing valve timing.

  The processes in steps 112 to 124 are executed for the intake control valves 22 of all the cylinders until the cylinder discrimination is completed. After completion of cylinder discrimination, the opening / closing valve timing of the intake control valve 22 is calculated for each cylinder, and the opening operation and the closing operation of the intake control valve 22 are executed for each cylinder. Eventually, when the oil pump is driven by the start of the internal combustion engine 2 and the hydraulic pressure rises and the variable valve timing mechanism 26 becomes operable, the determination result of step 110 becomes Yes and this routine ends. After the end of this routine, the ECU 30 controls the effective intake period according to the operating state of the internal combustion engine 2 by causing the variable valve timing mechanism 26 and the intake control valve 22 to cooperate.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the embodiment described above, an on / off valve is used as the intake control valve 22, but a valve capable of controlling the opening degree stepwise or continuously may be used. When using a valve capable of opening control, the following control can be performed to further improve the startability of the internal combustion engine 2. As shown in FIG. 2, when the intake control valve 22 is opened before the opening timing of the intake valve 8, the opening degree of the intake control valve 22 is set to a very small opening degree at the opening timing of the intake valve 8. Keep it. Further, as shown in FIG. 3, when the intake control valve 22 is opened after the opening timing of the intake valve 8, it is not opened suddenly but is opened minutely. Thus, by opening the intake control valve 22 with a small opening, the air flow path is narrowed and the intake flow velocity is increased. As a result, mixing of fuel and fresh air is promoted, combustion is improved, and startability of the internal combustion engine 2 is improved. Note that the opening degree and period when the intake control valve 22 is slightly opened may be set according to the water temperature. This is because the lower the engine temperature, the more likely the combustion is worsened and the mixing of fuel and fresh air is required. After the elapse of the predetermined period, the intake control valve 22 is opened until it is fully opened or opened according to the required air amount. As a specific control method of the opening at that time, the opening may be gradually increased little by little, or the opening may be continuously increased. Alternatively, the opening degree may be increased stepwise from a minute intermediate opening degree to a full opening degree or an opening degree corresponding to the required air amount.

  Moreover, in the said embodiment, although water temperature is used as a parameter representing the temperature of the internal combustion engine 2, if it is a parameter relevant to engine temperature, such as oil temperature and operation time, it will not be limited to water temperature.

  In the above embodiment, the stop position sensor 36 for determining the stop position of the variable valve timing mechanism 26 is provided. However, the stop position of the variable valve timing mechanism 26 at the start of the internal combustion engine 2 is always constant. In some cases, that is, when the variable valve timing mechanism 26 is always controlled to a fixed stop position when the internal combustion engine 2 is stopped, the stop position sensor 36 may be omitted.

  Further, the variable valve timing mechanism shown in FIG. 6 is merely an example of a variable valve timing mechanism applicable to the present invention. As long as it is hydraulic, a variable valve timing mechanism having another structure can be used.

  In the above embodiment, the throttle valve 20 is provided separately from the intake control valve 22, but the opening degree of the intake control valve 22 can be controlled, and sufficient airtightness is ensured when the valve is closed. If necessary, the throttle valve 20 may be eliminated and the intake control valve 22 may have the function of the throttle valve 20.

1 is a diagram showing a schematic configuration of an internal combustion engine system to which an intake air control device as an embodiment of the present invention is applied. It is explanatory drawing which shows operation | movement of an intake control valve when the variable valve timing mechanism has stopped at the most retarded position at the time of start-up of an internal combustion engine. It is explanatory drawing which shows operation | movement of an intake control valve when the variable valve timing mechanism has stopped at the most advanced angle position at the time of start-up of an internal combustion engine. It is a flowchart of a routine executed by the ECU when IG is turned on. It is a flowchart of a routine executed by the ECU after the IG is turned on until the variable valve timing mechanism becomes operable. It is a figure which shows schematic structure of the hydraulic system of the conventional variable valve timing mechanism.

Explanation of symbols

2 Internal combustion engine 4 Intake pipe 4a Intake port 6 Exhaust pipe 8 Intake valve 10 Exhaust valve 12 Combustion chamber 14 Crankshaft 20 Throttle valve 22 Intake control valve 24 Fuel injection valve 26 Variable valve timing mechanism 30 ECU
32 Crank angle sensor 36 Stop position sensor 38 Water temperature sensor

Claims (4)

A hydraulic variable valve timing mechanism that variably controls the valve timing of the intake valve and operates from a position where the valve timing of the intake valve is advanced most at the time of starting the internal combustion engine;
An intake control valve provided in the intake passage of each cylinder for opening and closing the intake passage;
When the internal combustion engine is started, the valve timing of the intake valve that has been most advanced is opened until the valve timing of the intake valve can be changed from the most advanced position by the operation of the variable valve timing mechanism. Control means for controlling the start timing of the effective intake period according to the opening timing of the intake control valve by opening the intake control valve on the retard side of the timing;
An intake control device for an internal combustion engine, comprising:
  The control means acquires a parameter related to the temperature of the internal combustion engine when the internal combustion engine is started, and controls the valve opening timing of the intake control valve according to the value of the parameter. An intake control device for an internal combustion engine as described.   The intake control apparatus for an internal combustion engine according to claim 1 or 2, wherein the control means opens the intake control valve after intake top dead center. A hydraulic variable valve timing mechanism that variably controls the valve timing of the intake valve;
An intake control valve provided in the intake passage of each cylinder for opening and closing the intake passage;
Determining means for determining a stop position of the variable valve timing mechanism;
Control means for controlling the start timing or end timing of the effective intake period by controlling the opening timing or closing timing of the intake control valve according to the determination result of the determination means,
When the internal combustion engine is started, and the determination means determines that the variable valve timing mechanism is stopped at a position where the valve timing of the intake valve is most retarded, the intake valve By closing the intake control valve on the advance side of the valve closing timing, the end timing of the effective intake period is controlled by the valve closing timing of the intake control valve,
When it is determined by the determining means that the variable valve timing mechanism is stopped at a position where the valve timing of the intake valve is advanced most, the variable valve timing mechanism is more retarded than the valve opening timing of the intake valve. An intake control device for an internal combustion engine, wherein the start timing of an effective intake period is controlled by opening the intake control valve by the opening timing of the intake control valve.

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