JP2005140007A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quicken the pressure rise of fuel in a high pressure fuel pump of a direct injection spark ignition internal combustion engine, which is driven by the engine for supplying the fuel to a fuel injection valve 7, by reducing friction at starting the engine to increase an engine speed. <P>SOLUTION: At starting the engine, a variable valve gear is used for reducing the lift amount of intake valves 5A, 5B to reduce the friction. The pressure rise of fuel is quickened to permit compression-stroke injection at starting. The combination with intake-stroke injection prevents interference between atomized fuel and the intake valve. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine, and more specifically, a lift amount of at least one of a fuel pump that is driven by the engine and supplies fuel to a fuel injection valve, and an intake valve and an exhaust valve that are driven by the engine. The present invention relates to a control device for an internal combustion engine, comprising a controllable variable valve device.

Patent Document 1 discloses a direct-injection spark-ignition internal combustion engine that directly injects fuel into a cylinder, and air that is sucked into the cylinder immediately after starting until the engine speed reaches peak rotation. It is disclosed that the valve lift amount of the intake valve is reduced so as to reduce the amount, thereby reducing the engine speed overshoot.
JP 2002-188472 A

  When starting the engine, it is necessary to quickly raise the pressure of the fuel supplied to the fuel injection valve in order to improve startability or reduce the HC emission immediately after starting. When driving, the increase in fuel pressure largely depends on the engine speed at the time of cranking or immediately after start-up, so it is desired to increase the engine speed at this time and quickly raise the fuel pressure. .

  In view of such a situation, the present invention reduces the engine friction when starting the engine, thereby reducing the load on the starter motor and increasing the engine speed during cranking, or the engine speed immediately after starting (independently). The object is to increase the pressure of the fuel discharged from the fuel pump driven by the engine and increase the rotational speed).

  Therefore, the present invention provides a variable pump capable of variably controlling a lift amount of at least one of a fuel pump driven by an engine and supplying fuel to a fuel injection valve, and an intake valve and an exhaust valve driven to open and close by the engine. A fuel pump driven by the engine by controlling at least one of the intake valve and the exhaust valve at a low lift characteristic at the time of engine start and / or until a predetermined period has elapsed after engine start. The fuel is supplied to the fuel injection valve.

  By controlling at least one of the intake valve and the exhaust valve to have a low lift characteristic at the time of engine start and / or until a predetermined period elapses after engine start, engine friction can be suppressed to a small size, so that the starter motor is enlarged. Even if not, the load on the starter motor is reduced and the engine speed during cranking is increased, or the engine speed immediately after starting (independently rotating speed) is increased. As a result, fuel from the fuel pump driven by the engine is increased. The pressure of the fuel supplied to the injection valve rises quickly.

In particular, in a low rotation range such as during cranking, the friction for opening and closing the intake valve and the exhaust valve occupies a large portion of the friction of the entire engine, so at least one of the intake valve and the exhaust valve is low. Setting the lift characteristic is effective for minimizing engine friction.
If the pressure of the fuel supplied to the fuel injection valve rises quickly, atomization of the fuel injected from the fuel injection valve is promoted, and the HC emission amount is reduced. Alternatively, since the fuel injection in the compression stroke can be started at an early stage, the amount of HC adhering to the combustion chamber wall surface is reduced as compared with the fuel injection in the intake stroke, resulting in a reduction in the HC emission amount.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a main part of a direct-injection spark ignition internal combustion engine (hereinafter referred to as an engine) showing an embodiment of the present invention, FIG. 2 is a plan layout view of the engine, and FIG. FIG.
In the combustion chamber 1 of the engine, a spark plug 2 is disposed at a substantially central portion on the upper surface (cylinder head) side. Then, two intake ports 3A and 3B and two exhaust ports 4A and 4B are opened so as to surround the spark plug 2, and the intake valves 5A and 5B and the exhaust valves 6A and 6B are mounted respectively.

The fuel injection valve 7 is installed between the intake ports 3A and 3B, and is inclined obliquely downward by a predetermined angle θ with respect to a plane perpendicular to the cylinder center axis C on the side of the combustion chamber 1 on the intake valves 5A and 5B side. The fuel is injected into the center of the combustion chamber 1 via the space between the two intake valves 5A and 5B.
The engine operation mode includes a stratified operation mode and a homogeneous operation mode. In the stratified operation mode, fuel injection is performed in the compression stroke, and a stratified mixture is formed around the spark plug 2. As a result, stratified combustion is performed at a very lean air-fuel ratio (A / F = 30 to 40) as a whole. On the other hand, in the homogeneous operation mode, fuel injection is performed in the intake stroke, and a homogeneous air-fuel mixture is formed in the entire combustion chamber 1, so that the stoichiometric or lean air-fuel ratio (A / F = 20 to 30) is achieved. Make homogeneous combustion.

FIG. 4 shows the configuration of the fuel system.
An electric low-pressure fuel pump 11 that pumps fuel in the fuel tank 10 into the fuel tank 10, a fuel filter 12 that filters fuel on the discharge side thereof, and a discharge-side pressure by returning surplus fuel to the fuel tank 10. And a low pressure regulator 13 for adjusting the pressure to a constant pressure (usually about 0.3 to 0.5 MPa).

The fuel pumped by the low pressure fuel pump 11 is supplied to the high pressure fuel pump 15 through the low pressure pipe 14.
The high-pressure fuel pump 15 includes a plunger pump 16, an electromagnetic control valve 17 provided on the suction side, and a check valve 18 provided on the discharge side.
The plunger pump 16 performs a suction / discharge operation by a reciprocating motion of a plunger driven by a pump drive cam connected to an engine camshaft.

The electromagnetic control valve 17 is controlled by the engine control unit (ECU) 100 so that the valve opens during the intake stroke of the plunger pump 16 and closes during the discharge stroke. The discharge amount of the fuel pump 15 (plunger pump 16) can be controlled.
Therefore, in the high-pressure fuel pump 15, the fuel is sucked through the suction-side electromagnetic control valve 17 when the plunger is lowered, and the fuel is passed through the check valve 18 on the discharge side after the electromagnetic control valve 17 is closed when the plunger is lifted. Is discharged.

The discharge side (check valve 18 side) of the high-pressure fuel pump 15 is connected to the high-pressure pipe 19. The fuel injection valves 7 corresponding to the number of cylinders are connected to the high-pressure pipes 19 through the branch pipes 20 that branch from now on. The fuel injection valves 7 are connected to the combustion chambers 1 of the cylinders of the engine as shown in FIG. It faces.
Further, a fuel pressure sensor 21 for detecting the fuel pressure inside the high pressure pipe 19 is attached, and the signal is input to the ECU 100. Furthermore, a relief valve 22 is attached to the end of the high-pressure pipe 19, and is connected to a return pipe 23 to the fuel tank 10 via the relief valve 22. The relief valve 22 is opened to release the pressure when the fuel pressure in the high-pressure pipe 19 increases excessively.

Here, in order to control the fuel pressure injected from the fuel injection valve 7, the fuel pressure in the high-pressure pipe 19 is controlled. This fuel pressure controls the closing timing of the electromagnetic control valve 17 by a signal from the ECU 100. By controlling the discharge amount of the high-pressure fuel pump 15, feedback control is performed to an arbitrary target fuel pressure (usually about 3 to 15 MPa).
The target fuel pressure is set according to operating conditions such as the engine speed and load, and is set at a higher pressure side at least during the compression stroke injection than during the intake stroke injection.

  The fuel pressure is controlled by variably adjusting the discharge amount of the high-pressure fuel pump with respect to the actual fuel injection amount calculated from the target fuel pressure and the required injection pulse width. When the high-pressure fuel pump discharge amount and the fuel injection amount are 1: 1, the flow rate balance is balanced and the fuel pressure is kept constant. When increasing the fuel pressure, the discharge amount is controlled so as to temporarily increase the discharge amount of the high-pressure fuel pump and return the flow rate balance to 1: 1 when the target fuel pressure is reached. The opposite is true when lowering fuel pressure.

  That is, in this fuel system, since the fuel pressure is controlled by the flow rate balance between the high pressure fuel pump discharge amount and the fuel injection amount, the control factor of the fuel pressure control is the high pressure fuel pump discharge amount. If the actual fuel pressure (fuel pressure sensor output) is lower than the target fuel pressure, increase the discharge amount of the high-pressure fuel pump to increase the fuel pressure until it reaches the target fuel pressure, and vice versa if the actual fuel pressure is higher than the target fuel pressure. Become.

Therefore, the ECU 100 calculates the discharge amount of the high-pressure fuel pump from the target fuel pressure and the fuel injection amount based on the target fuel pressure set according to the operating conditions, and based on this, the valve closing timing of the electromagnetic control valve 17 is set. The control is performed with reference to the crank angle sensor signal (engine speed) and the cam angle sensor signal (pump drive cam phase angle).
FIG. 5 shows the configuration of the variable valve operating apparatus. This example is a VVL + VTC formula.

At least on the camshaft 30 for driving the intake valves 5A and 5B, a low cam 31 having a low lift amount and a high cam 32 having a high lift amount are formed for each intake valve driven thereby.
The valve lifters of the intake valves 5A and 5B have a double cylinder structure of an inner cylinder 33 and an outer cylinder 34, and the inner cylinder 33 is integral with the valve stem. Although the outer cylinder 34 is slidable with respect to the inner cylinder 33, the inner cylinder 33 and the outer cylinder 34 can be integrated with a lock pin (not shown).

Here, the low cam 31 is opposed to the end surface of the inner cylinder 33, and the high cam 32 is opposed to the end surface of the outer cylinder 34.
Therefore, when the inner cylinder 33 and the outer cylinder 34 are not integrated, the intake valves 5A and 5B are driven by the low cam 31 via the inner cylinder 33. On the other hand, in a state where the inner cylinder 33 and the outer cylinder 34 are integrated by the lock pin, the intake valves 5A and 5B are driven by the high cam 32 having a large lift amount via the outer cylinder 34 → the lock pin → the inner cylinder 33. The

The lock pin is controlled by the hydraulic pressure supplied to the hydraulic port 35, and this hydraulic pressure is controlled by a solenoid valve (VVL solenoid) 37 upstream of the oil supply passage 36.
Therefore, the hydraulic pressure is controlled by turning on or off the VVL solenoid 37 by a signal from the ECU 100, and the low cam 31 or the high cam 32 is selectively switched by switching the state of the lock pin. This can be changed, and this constitutes a variable valve lift (VVL device).

On the other hand, the camshaft 30 is driven by the rotation of a crankshaft (not shown) being input to the sprocket 38 by a timing belt. A rotary solenoid (which can control the rotational phase of the camshaft 30 between the sprocket 38 and the camshaft 30). A VTC solenoid 39 is mounted.
Therefore, the valve timing can be changed by changing the rotational phase between the crankshaft and the camshaft by duty-controlling the energization amount of the VTC solenoid 39 by a signal from the ECU 100, thereby changing the valve timing. (VTC device) is configured.

  The ECU 100 receives a signal from a crank angle sensor 91 that detects the rotation angle of the crankshaft and a signal from a cam angle sensor 92 that can detect the rotation angle of the camshaft. Further, as the engine operating state, the engine speed Ne can be detected based on a signal from the crank angle sensor 91, and detection signals such as the intake air amount Qa, the throttle opening TVO, and the water temperature Tw are received from various sensors. Have been entered.

Based on these detection signals, the ECU 100 controls the valve lift by ON / OFF control of the VVL solenoid 37, and controls the valve timing by controlling the duty of the VTC solenoid 39.
6 and 7 show another configuration of the variable valve operating apparatus. This example is the VEL + VTC formula (see Japanese Patent Laid-Open No. 2000-89215).

  Above the valve lifter 40 at the ends of the intake valves 5A and 5B, a cam shaft 41 that is driven to rotate around the shaft in conjunction with a crankshaft (not shown) extends in the cylinder row direction. A swing cam 42 is fitted on the outer periphery of the cam shaft 41 so as to be swingable corresponding to the intake valves 5A and 5B. The swing cam 42 abuts against and presses the valve lifter 40. As a result, the intake valves 5A and 5B are driven to open and close against the spring force of the valve spring (not shown).

Here, between the cam shaft 41 and the swing cam 42, the posture of the link that mechanically links both 41 and 42 is changed, and the operating angle (opening and closing period) and the valve lift amount of the intake valves 5A and 5B are changed. A valve operating angle and a valve lift continuous variable device (VEL device) capable of continuously variably controlling are provided.
The VEL device includes a drive cam 43 that is eccentrically provided on the cam shaft 41 and rotates integrally with the cam shaft 41, a ring-shaped link 44 that is fitted on the outer periphery of the drive cam 43 so as to be relatively rotatable, and a cam shaft 41. A control shaft 45 extending substantially parallel to the cylinder row direction, a control cam 46 provided eccentrically with respect to the control shaft 45 and rotating integrally with the control shaft 45, and rotatable relative to the outer periphery of the control cam 46 And a rocker arm 47 whose one end is rotatably connected to the tip of the ring-shaped link 44, and is rotatably connected to the other end of the rocker arm 47 and the tip of the swing cam 42. 42 has a rod-like link 48 that mechanically cooperates.

  The cam shaft 41 and the control shaft 45 are rotatably supported on the cylinder head side of the engine via a bearing bracket. An output end of an actuator (VEL solenoid) 49 for changing the operating angle is connected to one end of the control shaft 45, and the control shaft 45 is rotationally driven around the axis within a predetermined control angle range by the VEL solenoid 49. At the same time, it is held at a predetermined rotational phase.

With such a configuration, when the cam shaft 41 rotates in conjunction with the crankshaft, the ring-shaped link 44 substantially translates via the drive cam 43, and the rocker arm 47 swings around the control cam 46, The swing cam 42 swings through the rod-shaped link 48, and the intake valves 5A and 5B are driven to open and close.
Further, when the control shaft 45 is rotated by the VEL solenoid 49, the center position of the control cam 46, which is the rocking center of the rocker arm 47, is changed, and the postures of the links 44, 48, etc. are changed. The swing angle range of 42 changes. As a result, the operating angle and the valve lift amount continuously change while the central phase of the operating angle remains substantially constant. More specifically, the operating angle and the valve lift amount are increased by rotating the control shaft 45 in one direction, and the operating angle and the valve lift amount are decreased by rotating in the other direction. Yes.

On the other hand, the camshaft 41 is driven by the rotation of the crankshaft being input to the sprocket 38 by the timing belt, and a rotary solenoid (VTC solenoid) capable of controlling the rotational phase between the sprocket 38 and the camshaft 41. ) 39 is mounted, thereby constituting a variable valve timing device (VTC device).
Next, the starting control according to the present invention will be described with reference to a flowchart.

FIG. 8 is a flowchart of the first embodiment of the starting control. A timing chart in this case is shown in FIG.
In S11, the engine is started with low lift and compression stroke injection. That is, the lift amount of the intake valve is reduced using the variable valve system (low lift), and in this state, stratified combustion is performed by the compression stroke injection, and the engine is started. However, the air-fuel ratio in the stratified combustion at this time is higher than the air-fuel ratio in the normal stratified combustion and is stoichiometric or weak lean (A / F = 15 to 16).

In S12, it is determined whether or not the start is completed depending on whether or not the engine speed Ne is equal to or greater than the predetermined value Ns. When the start is completed, the process proceeds to S13, and the lift amount of the intake valve is increased to the normal lift (high lift). Return to). Therefore, here, the intake valve is controlled to have a low lift characteristic during cranking for starting and until the engine speed after cranking reaches a predetermined value.
In S14, it is determined whether or not warming up of the exhaust purification catalyst is completed. When warming up is completed, the process proceeds to S15. Specifically, when a catalyst temperature sensor is provided, the catalyst temperature is detected by this. If the catalyst temperature sensor is not provided, the catalyst temperature is estimated from the water temperature Tw. Alternatively, the catalyst temperature is estimated based on the water temperature at the start and the integrated value of the intake air amount after the start. Then, it is determined whether or not the detected or estimated catalyst temperature is equal to or higher than a predetermined activation temperature. If the detected or estimated catalyst temperature is equal to or higher than the activation temperature, it is regarded that the warm-up is completed, and the process proceeds to S15 to Transition.

  According to the present embodiment, the engine friction can be kept small by controlling the intake valve to have a low lift characteristic when the engine is started. In other words, by setting the intake valve to a low lift, the amount of shortening of the valve spring for driving the intake valve can be reduced, and the required driving force can be reduced. Therefore, without increasing the size of the starter motor, the load on the starter motor is reduced and the engine speed at the time of cranking is increased, or the engine speed immediately after starting (independent rotation speed) is increased. As a result, the engine The pressure of the fuel supplied to the fuel injection valve from the high-pressure fuel pump driven by is quickly raised. If the pressure of the fuel supplied to the fuel injection valve rises quickly, atomization of the fuel injected from the fuel injection valve is promoted, and the HC emission amount is reduced.

  Further, according to the present embodiment, by performing fuel injection in the compression stroke when starting the engine, it is possible to reduce the HC emission amount at the time of starting. In other words, as described above, by increasing the fuel pressure at the time of start-up, it becomes possible to perform compression stroke injection at the time of start-up, and by causing stratified combustion by compression stroke injection at the time of start-up, the fuel is placed on the wall of the combustion chamber It can be prevented from adhering and HC emission can be reduced.

  Further, according to the present embodiment, the stratified combustion by the compression stroke injection is discharged from the engine by performing the fuel injection in the compression stroke until the warming-up of the exhaust purification catalyst of the engine is completed even after the engine is started. In addition to lowering the level of HC, the combustion stability is improved by collecting a rich air-fuel mixture around the spark plug, and the ignition timing can be retarded as much as the combustion stability is improved. Therefore, it is possible to increase the exhaust temperature.

FIG. 9 is a flowchart of the second embodiment of the starting control. A timing chart in this case is shown in FIG.
In S21, the engine is started with low lift and intake stroke injection. That is, the lift amount of the intake valve is reduced (low lift), and in this state, homogeneous combustion is performed by intake stroke injection, and the engine is started. The air-fuel ratio at this time is stoichiometric.

In S22, it is determined whether or not the start is completed depending on whether or not the engine speed Ne is equal to or greater than a predetermined value Ns, and the process proceeds to S23 when the start is completed.
In S23, the engine is switched to the stratified combustion by the compression stroke injection, that is, the compression stroke injection with stoichiometric or weak lean.
In S24, after switching to the compression stroke injection, the lift amount of the intake valve is returned to the normal lift (high lift).

In S25, it is determined whether or not warming up of the exhaust purification catalyst is completed, and when warming up is completed, the process proceeds to S26.
In S26, the routine proceeds to normal injection control (for example, intake stroke injection).
In particular, according to the present embodiment, when the engine is started, the lift amount of the intake valve is reduced, and in this state, fuel injection is performed in the intake stroke, thereby ensuring sufficient startability and fuel spraying. And the intake valve can be prevented, and the amount of HC emission at the time of starting can be reduced.

  In the case of the compression stroke injection, since the intake valves 5A and 5B are closed, the interference between the fuel spray and the intake valves 5A and 5B is not a problem. However, in the case of the intake stroke injection, the intake valves 5A and 5B are lifted. Therefore, interference between the fuel spray and the intake valves 5A and 5B becomes a problem. In FIGS. 1 and 2, the interference portion between the fuel spray and the intake valve is shown in black. A part of the injected fuel interferes with the intake valve, thereby inhibiting the formation of the air-fuel mixture in the cylinder. As a result, a large amount of liquid fuel is present in the cylinder, and the amount of HC discharged from the engine increases. .

However, as shown in FIG. 3, if the intake stroke injection is performed in a state where the lift amount of the intake valves 5A and 5B is reduced, the interference between the fuel spray and the intake valves 5A and 5B is prevented or at least reduced. It is possible to reduce the amount of HC emission at the start.
Further, according to the present embodiment, after the engine is started, by switching to the fuel injection in the compression stroke, the stratified combustion by the compression stroke injection can not only lower the level of HC discharged from the engine, but also the ignition Combustion stability is improved by collecting a rich air-fuel mixture around the plug, and the ignition timing can be retarded as much as the combustion stability is improved. Therefore, it is possible to increase the exhaust temperature for promoting warm-up of the catalyst. Further, since the compression stroke injection is performed after the fuel pressure has risen more reliably, stratified combustion becomes more reliable.

Further, according to this embodiment, after switching to the fuel injection in the compression stroke injection, the friction is suppressed until the compression stroke injection is reliably performed by returning the intake valve from the low lift characteristic to the normal lift characteristic. Controllability can be improved.
FIG. 10 is a flowchart of the third embodiment of the starting control. A timing chart in this case is shown in FIG.

In S31, the engine is started with low lift and intake stroke injection. That is, the lift amount of the intake valve is reduced (low lift), and in this state, homogeneous combustion is performed by intake stroke injection, and the engine is started.
In S32, it is determined whether or not the start is completed depending on whether or not the engine speed Ne is equal to or greater than a predetermined value Ns, and the process proceeds to S23 when the start is completed.
In S33, it is determined whether or not warming up of the exhaust purification catalyst is completed, and when warming up is completed, the process proceeds to S34.

In S34, the lift amount of the intake valve is returned to the normal lift (high lift).
In S35, the routine proceeds to normal injection control (for example, intake stroke injection).
In particular, according to the present embodiment, the engine is controlled at a low temperature by controlling the intake valve to have a low lift characteristic and performing fuel injection in the intake stroke until the warm-up of the exhaust purification catalyst of the engine is completed after the engine is started. While the friction is high, the driving force is reduced by a low lift, and torque shortage can be eliminated by intake stroke injection (homogeneous combustion) with higher torque than compression stroke injection (stratified combustion).

In the above embodiment, the fuel injection valve 7 is disposed on the side of the combustion chamber 1 and injects fuel toward the center of the combustion chamber via the space between the two intake valves 5A and 5B. As shown in FIGS. 12 and 13, the fuel injection valve 7 may be arranged in the downward direction along with the spark plug 2 in a substantially central portion on the upper surface (cylinder head) side of the combustion chamber 1.
FIG. 12 shows the time when the intake valve is in high lift, and the portion where the fuel spray and the intake valve interfere with each other in the case of intake stroke injection is shown in black. On the other hand, FIG. 13 shows that the intake valve is in a low lift state, and it can be seen that the interference between the fuel spray and the intake valve is reduced during the intake stroke injection.

1 is a cross-sectional view of a main part of an engine (at the time of high intake valve lift) showing an embodiment of the present invention. Plan layout of the engine Cross section of the main part when the intake valve is low lifted Configuration diagram of fuel system Configuration diagram of variable valve gear Other configuration diagram of variable valve gear Cross-sectional view of the main part of FIG. Flow chart of first embodiment of control at start-up Flow chart of second embodiment of control at start-up Flow chart of third embodiment of start-up control Time chart of first to third embodiments of starting control Sectional drawing of the principal part of the engine (at the time of high lift of the intake valve) showing another embodiment Cross section of the main part when the intake valve is low lifted

Explanation of symbols

1 Combustion chamber
2 Spark plug
3A, 3B Intake port
4A, 4B Exhaust port
5A, 5B Intake valve
6A, 6B Exhaust valve
7 Fuel injection valve
10 Fuel tank
11 Low pressure fuel pump
15 High pressure fuel pump
16 Plunger pump
17 Electromagnetic control valve
18 Check valve
30 camshaft
31 Lokham
32 Hi-Cam
37 VVL solenoid
39 VTC solenoid
41 camshaft
42 Swing cam
49 VEL solenoid
100 ECU

Claims (12)

A fuel pump that is driven by the engine to supply fuel to the fuel injection valve, and a variable valve operating device that can variably control the lift amount of at least one of the intake valve and the exhaust valve that are driven to open and close by the engine,
Fuel is supplied to the fuel injection valve from the fuel pump driven by the engine by controlling at least one of the intake valve and the exhaust valve to the low lift characteristic at the time of starting the engine and / or until a predetermined period after the engine starts. A control apparatus for an internal combustion engine.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel injection valve directly injects fuel into the combustion chamber.   3. The control apparatus for an internal combustion engine according to claim 2, wherein at least one of the intake valve and the exhaust valve is controlled to have a low lift characteristic during cranking for starting.   3. The control apparatus for an internal combustion engine according to claim 2, wherein at least one of the intake valve and the exhaust valve is controlled to have a low lift characteristic until the engine speed reaches a predetermined value after the start operation is started.   3. The control device for an internal combustion engine according to claim 2, wherein after the engine is started, at least one of the intake valve and the exhaust valve is controlled to have a low lift characteristic until the warming-up of the exhaust purification catalyst of the engine is completed.   3. The control device for an internal combustion engine according to claim 2, wherein fuel injection is performed in a compression stroke when the engine is started.   3. The control apparatus for an internal combustion engine according to claim 2, wherein fuel injection is performed in an intake stroke when the engine is started.   3. The control apparatus for an internal combustion engine according to claim 2, wherein fuel injection is performed during an intake stroke when the engine is started, and is switched to fuel injection during a compression stroke after the engine is started.   9. The control apparatus for an internal combustion engine according to claim 8, wherein after switching to fuel injection in the compression stroke, at least one of the intake valve and the exhaust valve is returned from a low lift characteristic to a normal lift characteristic.   3. The control of an internal combustion engine according to claim 2, wherein after the engine is started, the intake valve is controlled to have a low lift characteristic and fuel injection is performed in the intake stroke until the exhaust purification catalyst of the engine is warmed up. apparatus.   11. The fuel injection valve according to claim 2, wherein the fuel injection valve is disposed on a side portion of the combustion chamber and injects fuel to the combustion chamber central portion side through two intake valves. The control apparatus for an internal combustion engine according to any one of the above.   The control device for an internal combustion engine according to any one of claims 2 to 10, wherein the fuel injection valve is disposed at a substantially central portion on an upper surface side of the combustion chamber.

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