JPH06323168A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve startability without causing deterioration of emission by accelerating atomization of injection fuel at the time of starting an internal combustion engine. CONSTITUTION:A control device for an engine 1 is provided with a piston 3, intake valve 7, exhaust valve 8, fuel injection valve 11, variable valve timing mechanism 24, electronic control unit (ECU) 51, etc. In a CPU52 of the ECU51, the variable valve timing mechanism 24 and the fuel injection valve 11 are driven to be controlled. As a result, at the time of starting the engine, after closing the exhaust valve 8 further with the piston 3 arriving at the top dead center, the intake valve 7 is opened and closed with a delay from the valve close timing after starting. Simultaneously with opening the intake valve 7 by the variable valve timing mechanism 24, fuel is injected. Consequently at the time of starting, a negative pressure is generated in a combustion chamber 4, and fuel is injected instantaneously with introducing intake air by opening the intake valve 7, to promote atomization of injection fuel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine having a variable valve timing mechanism capable of adjusting the valve opening timing of an intake valve.

[0002]

2. Description of the Related Art Conventionally, there has been a variable valve timing mechanism for changing the rotational phase of an intake camshaft in accordance with the operating state of an internal combustion engine to advance or delay the intake valve opening / closing timing. As one of them, there is a technique in which the closing timing of the intake valve is advanced to near piston bottom dead center BDC at the time of engine start. This technique is intended to prevent the blowback of intake air by advancing the valve closing timing, increase the charging efficiency and the actual compression ratio, and improve the startability.

However, in order to improve the startability, it is not sufficient to simply secure the charging efficiency, and it is necessary to consider the securing of the engine speed. That is, when the internal combustion engine is started in the winter or cold regions, the sliding resistance of the piston is originally increased due to the increase in oil viscosity. In addition, if the charging efficiency is increased as described above, the compression resistance of the piston increases, the resistance received by the piston further increases, the engine speed hardly increases, and the engine startability deteriorates.

Therefore, for example, JP-A-60-138218
In the publication, at the cold start of the internal combustion engine, the valve closing timing of the intake valve is delayed from the valve closing timing at idling. According to this technique, during cranking of the internal combustion engine during cold start, the substantial filling amount is kept to a minimum, the compression resistance received by the piston is reduced, and the engine speed is quickly raised. It is possible to improve startability.

[0005]

However, in the latter technique, although the closing timing of the intake valve can be adjusted to reduce the compression resistance, no consideration is given to the fuel injection timing. Therefore, depending on how the fuel injection timing is set, the injected fuel may not be atomized. As a result, there are problems that the engine startability is not sufficiently improved and the emission at the time of starting is deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to promote atomization of the injected fuel at the time of starting the internal combustion engine and to improve the startability without deteriorating the emission. An object of the present invention is to provide a control device for an internal combustion engine capable of performing the above.

[0007]

In order to achieve the above-mentioned object, the present invention provides an internal combustion engine M3 for converting a reciprocating motion of a piston M1 into a rotary motion of a crankshaft M2 to obtain power as shown in FIG. The combustion chamber M of the internal combustion engine M3 is provided by being driven by the rotation of the crankshaft M2.
4, an intake valve M7 and an exhaust valve M8 for opening and closing an intake passage M5 and an exhaust passage M6 respectively, and a variable valve timing capable of adjusting at least the opening timing of the intake valve M7 among the intake valve M7 and the exhaust valve M8. A mechanism M9, a fuel injection valve M10 provided in the intake passage M5 for injecting fuel into the combustion chamber M4, and a starting state detecting means M11 for detecting a starting state of the internal combustion engine M3.
When the starting state of the internal combustion engine M3 is detected by the starting state detecting means M11, the exhaust valve M8 is closed and the intake valve M7 is opened after the piston M1 reaches the top dead center, and the engine is opened. First control means M12 for driving and controlling the variable valve timing mechanism M9 so as to close the intake valve M7 later than the closing timing after the start.
When the starting condition of the internal combustion engine M3 is detected by the starting condition detecting means M11, the fuel injection valve M10 is drive-controlled so as to inject fuel at the opening timing of the intake valve M7 by the variable valve timing mechanism M9. And second control means M13 for controlling.

[0008]

When the internal combustion engine M3 is started and its starting state is detected by the starting state detecting means M11, the variable valve timing mechanism M9 is drive-controlled by the first control means M12. By this drive control, the exhaust valve M8
Is closed, and the intake valve M7 is opened after the piston M1 reaches the top dead center. That is, in the intake stroke, there is a period in which both the exhaust valve M8 and the intake valve M7 are closed, and during this period the piston M1 moves downward from top dead center to bottom dead center. Therefore, a large negative pressure is generated in the combustion chamber M4 during the same period. When the intake valve M7 is opened in this state, due to the action of the negative pressure,
A mixture of intake air passing through the intake passage M5 and fuel injected from the fuel injection valve M10 is vigorously sucked into the combustion chamber M4.

When the starting state of the internal combustion engine M3 is detected by the starting state detecting means M11, the fuel injection valve M1
0 is driven and controlled by the second control means M13. By this drive control, fuel is injected at the same time when the intake valve M7 is opened.

Therefore, at the time of starting the internal combustion engine M3, the intake valve M7 is opened when negative pressure is generated in the combustion chamber M4, and intake air is introduced into the combustion chamber M4 and is also introduced. At the same time, fuel is injected from the fuel injection valve M10. The negative pressure at this time promotes atomization of the injected fuel.

When the starting state of the internal combustion engine M3 is detected, the variable valve timing mechanism M9 is drive-controlled by the first control means M12, and the valve closing timing of the intake valve M7 is later than the valve closing timing after the engine is started. Is also delayed. For this reason,
In the compression stroke of the internal combustion engine M3 in which the piston M1 moves from the bottom dead center to the top dead center, the compression resistance received by the piston M1 decreases. Along with this decrease, the engine speed at the start tends to increase, and the startability improves.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of a multi-cylinder gasoline engine (hereinafter, simply referred to as an engine) 1 as an internal combustion engine mounted on an automobile. In the cylinder block 1a of the engine 1, a number of cylinders 2 are arranged in parallel according to the number of cylinders, and a piston 3 is housed in each cylinder 2 so as to be vertically reciprocable. The piston 3 is connected to the crankshaft C by a connecting rod 15. The reciprocating motion of the piston 3 is converted into a rotary motion by the connecting rod 15, and the crankshaft C is rotationally driven.

A combustion chamber 4 is formed above the piston 3, and an intake passage 5 and an exhaust passage 6 are in communication therewith. A communication portion between the combustion chamber 4 and the intake passage 5 is opened / closed by an intake valve 7, and a communication portion between the combustion chamber 4 and the exhaust passage 6 is opened / closed by an exhaust valve 8. The intake valve 7 and the exhaust valve 8 are the crankshaft C
Are reciprocated by camshafts 9 and 10 which are drivingly connected to each other.

The engine 1 introduces a mixture of the outside air from the intake passage 5 and the fuel injected from the fuel injection valve 11 into the combustion chamber 4 via the intake valve 7. Then, the engine 1 explodes the air-fuel mixture in the combustion chamber 4 by the spark plug 12 to obtain a driving force, and then discharges the exhaust gas to the exhaust passage 6 via the exhaust valve 8.

The intake passage 5 is provided with a throttle valve 13 which is opened / closed in conjunction with the operation of an accelerator pedal (not shown). The opening / closing of the throttle valve 13 causes the amount of intake air into the intake passage 5. Is adjusted.
A throttle opening sensor 14 that detects the opening (throttle opening TA) is attached near the throttle valve 13. An air flow meter 1 for detecting the intake air amount Q is provided upstream of the throttle valve 13.
6 are provided. The air flow meter 16 includes an intake air temperature sensor 17 for detecting the temperature of the air taken by the engine 1 (intake air temperature THA).

The ignition voltage distributed by the distributor 18 is applied to the ignition plug 12. The distributor 18 distributes the high voltage output from the igniter 19 to each spark plug 12 in synchronization with the rotation of the crankshaft C.
The ignition timing of is determined by the high voltage output timing from the igniter 19.

The distributor 18 incorporates a rotation speed sensor 21 as a starting state detecting means and a cylinder discrimination sensor 22. The rotation speed sensor 21 is the crankshaft C.
A pulse signal is generated at every constant angle (for example, 30 ° CA), the crank angle is detected from this pulse signal, and the rotation speed of the crankshaft C (engine speed NE) is calculated from the number of pulse signals per unit time. To detect. Further, the cylinder discrimination sensor 22 generates a pulse signal for each predetermined angle of the crankshaft C (for example, 360 ° CA),
From this pulse signal, the crank angle reference position (top dead center TD
C) is detected and cylinder discrimination is performed.

In the cylinder block 1a of the engine 1,
A water temperature sensor 23 for detecting the temperature of the cooling water (cooling water temperature THW) is attached. A vehicle speed sensor 20 for detecting the traveling speed (vehicle speed SPD) of the automobile is provided in the transmission (not shown).

In addition, in this embodiment, a variable valve timing mechanism 24 for adjusting the valve opening timing and valve closing timing of the intake valve 7 is provided. Next, this mechanism 24
Will be described in detail.

As shown in FIG. 3, a cam shaft 9 for driving the intake valve 7 to open and close is rotatably supported by the engine 1 by a cylinder head 1b and a bearing cap 30. Also, the cylinder head 1b
Journal oil passages 25 and 26 for supplying lubricating oil to the cam journal 9a are formed in the cam shaft 9 and the cam shaft 9, respectively. The lubricating oil sucked up from the oil pan 28 by the oil pump 27 during the operation of the engine 1 passes through the oil filter 29 and the journal oil passage 2
5, 26, and is supplied to the cam journal 9a.

The variable valve timing mechanism 24 is provided at the front end portion (left end portion in FIG. 3) of the camshaft 9. The mechanism 24 has a plurality of outer teeth 31 on the outer periphery and a pulley main body 33 having a housing recess 32 on the front side, and is fixed by a bolt 34 at the front end of the camshaft 9 so as to cover the housing recess 32. And a cap 35. A viscous coupling (viscous coupling) 36 for cushioning is provided between the open end of the pulley body 33 and the outer periphery of the cap 35. The viscous coupling 36 includes an outer plate 37 that is press-fitted and fixed to the pulley body 33, and an inner plate 38 that is formed on the outer periphery of the cap 35. A high-viscosity viscous fluid is enclosed between the two 37 and 38. There is.

A ring gear 39 is interposed between the pulley body 33 and the cap 35 to connect the both 33, 35. That is, the ring gear 39 is housed in the housing recess 32 of the pulley body 33 that is sealed by the cap 35. The ring gear 39 has helical teeth on both teeth 39a and 39b provided on the inner and outer circumferences thereof, and the ring gear 39 is rotated relative to the camshaft 9 by the movement of the ring gear 39 in the axial direction (left and right direction in FIG. 3). It is movable. The teeth 39a and 39b mesh with the inner teeth 33a of the pulley body 33 and the inner teeth 35a of the cap 35, respectively. The pulley body 33 is drivingly connected to the crankshaft C of the engine 1 via the timing belt 41 that is wound around the outer teeth 31 of the pulley body 33.

Therefore, by transmitting the rotation of the crankshaft C to the pulley main body 33, the pulley main body 33 and the cap 35 connected by the ring gear 39 are integrally rotated, and the camshaft 9 is rotationally driven. .

The front end side of the ring gear 39 in the accommodating recess 32 of the pulley body 33 is a pressurizing chamber 44, in which the control oil passages 42 and 43 formed in the cylinder head 1b and the cam shaft 9 are provided. The control oil that is sent acts. Similarly, in the accommodation recess 32, the ring gear 39
At the rear end side is a spring chamber 45, where
A balancing spring 46 facing the control hydraulic pressure is housed in a compressed state.

The variable valve timing mechanism 24 also includes an oil switching valve 47. The oil switching valve 47 is for supplying or stopping a part of the lubricating oil sent from the oil filter 29 to the journal oil passage 25 to the pressurizing chamber 44 via the control oil passages 42 and 43. When the oil switching valve 47 is closed during the operation of the engine 1, the urging force of the spring 46 positions the ring gear 39 on the front side as shown in FIG. The opening / closing timing of the intake valve 7 at this time is referred to as a start timing.

On the other hand, when the oil switching valve 47 is opened from the above-mentioned state, the control oil is introduced into the pressurizing chamber 44. Then, the control oil pressure is applied to the front end side of the ring gear 39, and the ring gear 39 is rotated while moving backward against the biasing force of the spring 46. As a result, the intake camshaft 9 is twisted, and the relative position of the camshaft 9 and the pulley body 33 in the rotational direction is changed. At this time, the opening timing and closing timing of the intake valve 7 are both normal timing earlier than the start timing.

When the camshaft 9 is twisted, backlash is generated in the ring gear 39, but rattling due to the backlash is buffered by the action of the viscous coupling 36, and abnormal noise is suppressed. In addition, a return oil passage 48 is formed in a part of the pulley body 33 and the cam shaft 9 in order to return the control oil leaking from the pressurizing chamber 44 of the accommodation recess 32 to the spring chamber 45 to the oil pan 28. There is. Oil return holes 49 are formed in the cylinder head 1b and the bearing cap 30 that support the camshaft 9, respectively.

By the way, FIG. 4 shows the opening / closing valve timing of the intake valve 7 at the start timing and the normal timing,
Also, the opening / closing valve timing of the exhaust valve 8 is shown in relation to the valve lift amount. The intake valve 7 is about 35 ° after the top dead center TDC at the start timing as shown by the solid line, for example.
The valve opens at CA and closes at about 80 ° CA after bottom dead center BDC. In addition, the intake valve 7 is at about 5 ° before the top dead center TDC at the normal timing, as shown by a chain double-dashed line, for example.
The valve opens at CA and closes at about 40 ° CA after bottom dead center BDC. On the other hand, the opening / closing timing of the exhaust valve 8 is not changed,
For example, the valve is opened at about 40 ° CA before the bottom dead center BDC and closed at about 5 ° CA after the top dead center TDC.

As shown in FIG. 2, the throttle opening sensor 14, the air flow meter 16, and the intake air temperature sensor 1 described above are used.
The vehicle speed sensor 20, the rotation speed sensor 21, the cylinder discrimination sensor 22, and the water temperature sensor 23 are electrically connected to the input side of an electronic control unit (hereinafter, simply referred to as “ECU”) 51. Further, each fuel injection valve 11, the igniter 19 and the oil switching valve 47 are electrically connected to the output side of the ECU 51.

The ECU 51 is a central processing unit (hereinafter referred to as a CPU) as a first control means and a second control means.
52, read-only memory (hereinafter referred to as ROM) 5
3, random access memory (hereinafter referred to as RAM) 5
4, an input port 55 and an output port 56, which are connected to each other by a bus 57. CPU 52
Executes various arithmetic processes according to a preset control program, and the ROM 53 stores in advance a control program and initial data required for the CPU 52 to execute the arithmetic processes. The RAM 54 also temporarily stores the calculation result of the CPU 52.

The CPU 52, via the input port 55, the throttle opening sensor 14, the air flow meter 16, the intake air temperature sensor 17, the vehicle speed sensor 20, the rotation speed sensor 21,
The signals from the cylinder discrimination sensor 22 and the water temperature sensor 23 are input. Based on these detection signals, the CPU 52 drives the fuel injection valve 11, the igniter 19 and the oil switching valve 47 connected to the output port 56 to execute combustion injection control, valve timing control, etc., respectively.

Next, the operation of this embodiment constructed as described above will be described. The flowchart of FIG. 5 shows a routine for controlling the valve timing of the intake valve 7 among the processes executed by the CPU 52. Further, the flowchart of FIG. 6 shows a routine for controlling fuel injection by the fuel injection valve 11. All of these routines are executed at predetermined time intervals after the ignition key is turned on to start the engine 1.

When the valve timing control routine of FIG. 5 is started, the CPU 52 first reads the engine speed NE by the rotation speed sensor 21 in step 101. Subsequently, in step 102, the CPU 52
It is determined whether the engine speed NE is equal to or higher than a predetermined speed (for example, 500 rpm). If the determination condition of step 102 is not satisfied (NE <50
0 rpm), the CPU 52 determines that the engine 1 is being started, and in step 103 the oil switching valve 4
A control signal for closing valve 7 is output, and this routine ends. Then, the supply of the control oil to the pressurizing chamber 44 is stopped and the control oil pressure is not applied to the front end of the ring gear 39, so that the ring gear 3 is urged by the spring 46.
9 is held in the position shown in FIG. As a result, as shown by the solid line in FIG. 4, both the opening timing and the closing timing of the intake valve 7 are later than the closing timing of the exhaust valve 8, and the intake valve 7 and the intake valve 7 near the top dead center TDC at the end of exhaust. The period (valve overlap) in which both of the exhaust valves 8 are open is eliminated.

On the other hand, when the determination condition of step 102 is satisfied (NE ≧ 500 rpm), the CPU 52 determines that the start of the engine 1 is completed, and a control signal for opening the oil switching valve 47 is issued in step 104. Output and end this routine. Then, the control oil is supplied to the pressurizing chamber 44, the control oil pressure is applied to the front end of the ring gear 39, and the ring gear 39 moves backward while rotating. As a result, the camshaft 9 and the pulley body 33
The relative position of the intake valve 7 in the rotational direction is changed, and the valve opening timing and the valve closing timing of the intake valve 7 are both advanced as shown by the chain double-dashed line in FIG. Then, the valve overlap between the intake and exhaust valves 7 and 8 becomes a predetermined value (about 10 ° CA in this case) larger than 0 ° CA. Then, the intake efficiency is increased by utilizing the inertia, and a high output is obtained.

As described above, in the valve timing control routine, the opening / closing valve timing of the intake valve 7 is changed between when the engine 1 is started and after the start of the engine 1. Especially when starting,
The valve overlap between the exhaust valves 7 and 8 is adjusted to be negative. During this negative period (the period from the closing of the exhaust valve 8 to the opening of the intake valve 7), the combustion chamber 4
The inside is greatly depressurized and becomes negative pressure.

Next, the fuel injection control routine of FIG. 6 will be described. When this routine is started, the CPU 52
First, at step 201, the intake air amount Q by the air flow meter 16, the intake air temperature THA by the intake air temperature sensor 17, the engine speed NE by the rotation speed sensor 21, the reference position signal by the cylinder discrimination sensor 22, the cooling water temperature THW by the water temperature sensor 23. Various data relating to the operating state of the engine 1 such as

Next, in step 202, the CPU 52 determines that the engine speed NE in step 201 is 50.
It is determined whether it is 0 rpm or more. Step 202
When the determination condition of is not satisfied (NE <500rp
m), the CPU 52 determines that the engine 1 is in the starting state, proceeds to step 203, and calculates the starting injection time TAUST, which is the time for energizing the fuel injection valve 11 at the time of starting.

Generally, when the engine 1 is started,
Since the intake air amount Q is small, the detection accuracy of the air flow meter 16 is not very high. Therefore, in the calculation of the injection time TAUST at the time of starting, the injection time corresponding to the cooling water temperature THW is obtained from, for example, the map regardless of the intake air amount Q and the engine speed NE. In this map, the cooling water temperature TH
The lower W (the cooler the engine 1) is, the less the fuel adhered to the wall surface of the intake passage 5 is vaporized. Therefore, the injection time is set longer on the low temperature side, and the cooling water temperature TH is set.
The injection time is set shorter as W increases. Then, the invalid injection time is added to the injection time obtained from the map, and the addition result is the injection time TAUS at the time of starting.
Let T. The invalid injection time is a time for correcting the operation delay of the fuel injection valve 11.

Next, the CPU 52 calculates the injection timing at startup in step 204. That is, the intake valve 7
Is opened (in this case, about 35 ° after TDC TDC)
CA). Then, the CPU 52 proceeds to step 205.
In the above, the drive signal is output to the fuel injection valve 11 so that the fuel injection is started at the above-mentioned start-up injection timing and the fuel injection is ended after the start-up injection time TAUST has elapsed. After executing step 205, the CPU 52 ends the fuel injection control routine.

On the other hand, when the determination condition of step 202 is satisfied (NE ≧ 500 rpm), the CPU 52 determines that the engine 1 has been started, and calculates the post-start injection time TAU in step 206. In this calculation,
From the engine speed NE and the intake air amount Q, the intake air amount per rotation (Q / NE) is obtained, and this is multiplied by a constant to obtain the basic injection time. The operating state of the engine 1 at that time (engine speed NE, cooling water temperature TH
W, intake air temperature THA, intake air amount Q, vehicle speed SPD, etc.) to correct the basic injection time. The invalid injection time of the fuel injection valve 11 is added to the corrected value, and the addition result is set as the post-start injection time TAU.

Subsequently, in step 207, the CPU 52 calculates the post-start injection timing according to the operating state of the engine 1 at that time according to a preset map or calculation formula. In the present embodiment, the injection timing is determined in the middle of valve overlap (top dead center TDC in FIG. 4) when both the intake valve 7 and the exhaust valve 8 are opened.
Then, in step 208, the CPU 52 outputs a drive signal to the fuel injection valve 11 so that the fuel injection is started at the post-start injection timing and the fuel injection is ended after the post-start injection time TAU has elapsed. After executing step 208, the CPU 52 ends the fuel injection control routine.

As described above, in the present embodiment, it is determined based on the engine speed NE whether the engine 1 is being started or has been started when controlling the valve timing (step 102). Then, the oil switching valve 47 is drive-controlled according to the determination result (steps 103 and 104), and the variable valve timing mechanism 2
The operating states of 4 are switched. By this switching, in the intake stroke at the time of starting the engine 1, the exhaust valve 8 is closed and the intake valve 7 is closed after the piston 3 reaches the top dead center TDC (in this case, about 35 ° CA after TDC). The valve is opened. That is, the piston 3 descends from the top dead center TDC to the bottom dead center BDC while the exhaust valve 8 and the intake valve 7 are both closed. During this period, a large negative pressure is generated in the combustion chamber 4. In this state, intake valve 7
Is opened, the mixture of intake air passing through the intake passage 5 and fuel injected from the fuel injection valve 11 is sucked into the combustion chamber 4 by the action of the negative pressure.

Further, in the fuel injection control, it is judged based on the engine speed NE whether the engine 1 is being started or the start is completed (step 202), and the fuel injection valve 11 is decided according to the judgment result. Drive controlled. By this drive control, when the engine 1 is started, fuel is injected almost at the same time as the intake valve 7 is opened (steps 203 to 205).

Therefore, when the engine 1 is started,
When a large negative pressure is generated in the combustion chamber 4, the intake valve 7 is opened to introduce the intake air into the combustion chamber 4, and at the same time, the fuel is injected from the fuel injection valve 11. The action of this negative pressure promotes atomization of the injected fuel, facilitates stable and complete combustion of the injected fuel, and reduces hydrocarbons (HC) in the exhaust gas at the time of starting.

When the engine 1 is started, the closing timing of the intake valve 7 is delayed from the closing timing after the start (about 40 ° CA after bottom dead center BDC → about 80 after bottom dead center BDC).
° CA). Therefore, in the compression stroke in which the piston 3 moves from the bottom dead center BDC to the top dead center TDC, the piston 3
The compression resistance received by is reduced. With this decrease, the engine speed NE at the time of starting (at the time of cranking) is likely to increase, and the startability is improved.

After the start of the engine 1, the intake valve 7 is opened at the timing corresponding to the operating state, and the fuel is injected at the timing corresponding to the operating state. Further, in the present embodiment, the amount of fuel adhering to the intake port, which is the communication point between the intake passage 5 and the combustion chamber 4, is reduced. The amount of injected fuel can be reduced by the amount of the reduction, which is advantageous in improving fuel efficiency. Further, since it is possible to prevent the air-fuel mixture from becoming too rich by reducing the amount of injected fuel, it is also advantageous in improving the smoldering of the ignition plug 12 (a phenomenon in which black dry carbon adheres to the entire ignition part).

The present invention is not limited to the configuration of the above-mentioned embodiment, and may be arbitrarily modified within the scope not departing from the spirit of the invention, for example, as follows. (1) In the above embodiment, the variable valve timing mechanism 24 of hydraulically operated type is used, but other types of variable valve timing mechanism such as a type driven by an electric motor may be used.

(2) In the above embodiment, the teeth 39 on the inner and outer circumferences of the ring gear 39 in the variable valve timing mechanism 24.
Although both a and 39b are helical teeth, only one of the teeth 39a and 39b may be helical teeth.

(3) The valve opening timing and valve closing timing of the exhaust valve 8 as well as the intake valve 7 may be controlled.

[0050]

As described above in detail, according to the present invention, when the internal combustion engine is started, the exhaust valve is closed, and the intake valve is opened after the piston reaches the top dead center. The fuel is injected from the fuel injection valve at the same time as the valve is opened, and the intake valve is closed later than the valve closing timing after the engine is started. It has an excellent effect that the startability can be improved without causing deterioration.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a schematic configuration diagram of an embodiment in which the present invention is embodied in a gasoline engine for automobiles.

FIG. 3 is a sectional view of a variable valve timing mechanism according to an embodiment.

FIG. 4 is a characteristic diagram showing a relationship between a crank angle and a valve lift amount of both intake and exhaust valves in one embodiment.

FIG. 5 is a flowchart illustrating a valve timing control routine executed by a CPU in an embodiment.

FIG. 6 is a flowchart illustrating a fuel injection control routine executed by a CPU in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 3 ... Piston, 4 ... Combustion chamber, 5 ... Intake passage, 6 ... Exhaust passage, 7 ... Intake valve,
8 ... Exhaust valve, 11 ... Fuel injection valve, 21 ... Rotation speed sensor as starting state detecting means, 24 ... Variable valve timing mechanism, 52 ... CPU as first control means and second control means, C ... Crank Shaft, TDC ... top dead center

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F02D 43/00 301 J Z

Claims (1)

[Claims] 1. An intake passage provided in an internal combustion engine for converting a reciprocating motion of a piston into a rotational motion of a crankshaft to obtain power, and being driven by rotation of the crankshaft to communicate with a combustion chamber of the internal combustion engine. An intake valve and an exhaust valve that open and close the exhaust passage, and a variable valve timing mechanism that can adjust at least the opening timing of the intake valve of the intake valve and the exhaust valve; A fuel injection valve for injecting fuel, a starting state detecting means for detecting a starting state of the internal combustion engine, and an exhaust valve closed and a piston when the starting state of the internal combustion engine is detected by the starting state detecting means. The intake valve is opened after the vehicle reaches the top dead center,
A first control for driving the variable valve timing mechanism so that the intake valve is closed later than the valve closing timing after the engine is started.
When the starting state of the internal combustion engine is detected by the control means and the starting state detecting means, the fuel injection valve is drive-controlled to inject fuel at the opening timing of the intake valve by the variable valve timing mechanism. A control device for an internal combustion engine, comprising: