JP2002195059A - Control device for variable valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten cranking period of starting cooling, in an internal combustion engine provided with a variable valve system. SOLUTION: This control device of the variable valve system for the internal combustion engine is provided with the variable valve system having changeable opening timing of, at least one of an intake valve and an exhaust valve of the internal combustion engine and/or the lift distance and a valve system control means for controlling the variable valve system, to increase the exhaust quantity flowing backward to the intake system of the internal combustion engine compared with that of the initial combustion and expansion, when the initial combustion and expansion are generated in starting cooling of the internal combustion engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine provided with a variable valve mechanism capable of arbitrarily changing the opening / closing timing and / or the lift of at least one of an intake valve and an exhaust valve.

[0002]

2. Description of the Related Art In recent years, in internal combustion engines mounted on automobiles and the like, at least one of opening and closing timings of an intake valve and an exhaust valve has been set for the purpose of improving net thermal efficiency, improving exhaust emission, or reducing fuel consumption. An internal combustion engine having a variable valve mechanism capable of arbitrarily changing a lift amount has been developed.

As a technique utilizing such a variable valve mechanism, for example, a valve timing control device for an internal combustion engine as disclosed in Japanese Patent Application Laid-Open No. 6-346768 has been proposed.

[0004] The valve timing control apparatus for an internal combustion engine described in the above publication includes a variable valve timing mechanism for driving at least one of an intake valve and an exhaust valve of the internal combustion engine to vary a valve overlap amount. When the engine is cold, a relatively high temperature exhaust gas is caused to flow back into the intake passage by increasing the valve overlap amount in accordance with the increase correction of the fuel injection amount, thereby increasing the intake air temperature and atomizing the fuel. It is to try to.

Further, the above-described valve timing control device for an internal combustion engine, when the internal combustion engine is cold started, reduces the valve overlap amount to return the fuel flowing into the combustion chamber to the intake passage. After the start of the internal combustion engine is completed, the valve overlap amount is increased to promote the atomization of the fuel.

[0006]

By the way, during the period from the start of the internal combustion engine to the completion of the start, that is, during the so-called cranking period, if the valve overlap amounts of all the cylinders are reduced, the intake air temperature rises and fuel consumption increases. Atomization could not be achieved, and the cranking period could be prolonged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a variable valve mechanism which can change the opening / closing timing and / or the lift of at least one of an intake valve and an exhaust valve. In an internal combustion engine, an object is to reduce a time required for starting the internal combustion engine.

[0008]

The present invention employs the following means to solve the above-mentioned problems. That is, a control device for a variable valve mechanism for an internal combustion engine according to the present invention includes a variable valve mechanism capable of changing the opening / closing timing and / or the lift amount of at least one of an intake valve and an exhaust valve of the internal combustion engine; And a valve operating mechanism control means for controlling the variable valve operating mechanism such that when an initial explosion occurs during a cold start of the engine, the amount of exhaust gas flowing back into the intake system of the internal combustion engine increases as compared to before the initial explosion occurs. It is characterized by the following.

In the control device for a variable valve mechanism for an internal combustion engine constructed as described above, when an initial explosion occurs during a cold start of the internal combustion engine, the valve mechanism control means controls the exhaust gas flowing backward to the intake system of the internal combustion engine. The variable valve mechanism is controlled so that the amount increases.

That is, when the internal combustion engine is cold-started, the valve operating mechanism control means controls the operation of the internal combustion engine after the first explosion (first explosion) occurs, as compared to before the first explosion occurs. The variable valve mechanism is controlled to increase the amount of exhaust gas flowing backward to the intake system.

In this case, since the amount of exhaust gas flowing back to the intake system of the internal combustion engine after the first explosion occurs, the exhaust gas which has become hot due to the initial explosion easily flows back to the intake system of the internal combustion engine.

As a result, after the first explosion occurs, the intake air of the internal combustion engine rises in temperature due to the heat of the exhaust gas. At this time, for example, when the fuel is injected from the fuel injection valve into the high-temperature intake air, it is possible to promote the atomization of the fuel.

In the control apparatus for a variable valve operating mechanism for an internal combustion engine according to the present invention, when the internal combustion engine has a plurality of cylinders, the valve operating mechanism control means, for example, controls all the valves after the first explosion occurs. The variable valve mechanism may be controlled so that the amount of exhaust gas flowing back to the intake system for the cylinder increases.The amount of exhaust gas flowing back to the intake system only for the cylinder where the first explosion occurred, and after that the explosion The variable valve mechanism may be controlled so that the amount of exhaust gas that flows back to the intake system increases sequentially for each generated cylinder, or a plurality of cylinders are divided into a group including at least two cylinders, and the first explosion is performed. The variable valve mechanism is designed to increase the amount of exhaust gas flowing back to the intake system only for the group that includes the cylinder in which the explosion has occurred, and then to increase the amount of exhaust gas that flows back to the intake system for each group including the cylinder in which the explosion has occurred. Control It may be so.

Next, a control device for a variable valve mechanism for an internal combustion engine according to the present invention provides a variable valve mechanism capable of changing the opening / closing timing and / or lift of at least one of an intake valve and an exhaust valve of the internal combustion engine. Valve actuation mechanism control means for controlling the variable valve actuation mechanism such that, when an initial explosion occurs during a cold start of the internal combustion engine, the valve overlap amount between the intake valve and the exhaust valve increases as compared to before the occurrence of the initial explosion. And the following.

In the control device for a variable valve mechanism for an internal combustion engine configured as described above, when an initial explosion occurs at the time of cold start of the internal combustion engine, the valve mechanism control means determines whether or not the intake valve and the exhaust valve have a valve overflow. The variable valve mechanism is controlled so that the lap amount increases compared to before the first explosion occurred.

That is, when the internal combustion engine is cold-started, the valve operating mechanism control means controls the amount of valve overlap between the intake valve and the exhaust valve after the initial explosion as compared to before the initial explosion. , The variable valve mechanism is controlled.

In this case, since the amount of valve overlap between the intake valve and the exhaust valve is increased after the first explosion occurs, the exhaust gas that has become hot due to the first explosion easily flows back to the intake system of the internal combustion engine.

As a result, after the first explosion occurs, the intake air of the internal combustion engine rises in temperature due to the heat of the exhaust gas. At this time, for example, when the fuel is injected from the fuel injection valve into the high-temperature intake air, it is possible to promote the atomization of the fuel.

Next, a control device for a variable valve mechanism for an internal combustion engine according to the present invention is a variable valve mechanism capable of changing the opening / closing timing and / or lift of at least one of an intake valve and an exhaust valve of the internal combustion engine. When the first explosion occurs during a cold start of the internal combustion engine, the variable valve mechanism is configured to increase the lift amount of the intake valve when the intake valve and the exhaust valve overlap with each other before the first explosion occurs. And a valve operating mechanism control means for controlling the valve operating mechanism. In the control device for the variable valve mechanism for an internal combustion engine configured as described above, when an initial explosion occurs at the time of a cold start of the internal combustion engine, the valve mechanism control means controls the intake valve when the intake valve and the exhaust valve overlap. The variable valve mechanism is controlled so that the lift amount of the valve increases compared to before the first explosion occurred.

That is, in the case where the internal combustion engine is cold-started, the valve operating mechanism control means is provided when the intake valve and the exhaust valve overlap each other after the initial explosion occurs, as compared with before the initial explosion occurs. The variable valve mechanism is controlled so as to increase the lift amount of the intake valve at the time.

In this case, after the occurrence of the first explosion, the lift amount of the intake valve when the intake valve and the exhaust valve overlap each other increases, so that the exhaust gas that has become hot due to the first explosion passes through the intake valve to the intake air of the internal combustion engine. Backflow to the system becomes easier.

As a result, after the first explosion occurs, the intake air of the internal combustion engine is heated by the heat of the exhaust gas. At this time, for example, when the fuel is injected from the fuel injection valve into the high-temperature intake air, the atomization of the fuel can be promoted.

Here, as the variable valve mechanism according to the present invention, an electromagnetically driven valve mechanism that opens and closes an intake valve and / or an exhaust valve by using an electromagnetic force can be exemplified.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of a control device for a variable valve mechanism for an internal combustion engine according to the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 are views showing an embodiment of an internal combustion engine to which the present invention is applied and an intake and exhaust system thereof. The internal combustion engine 1 shown in FIGS. 1 and 2 has four cylinders 21.
It is a stroke cycle water-cooled gasoline engine.

The internal combustion engine 1 includes a cylinder block 1b in which four cylinders 21 and a cooling water passage 1c are formed, and a cylinder head 1 fixed on an upper portion of the cylinder block 1b.
a.

A crankshaft 23, which is an engine output shaft, is rotatably supported by the cylinder block 1b. The crankshaft 23 is connected via a connecting rod 19 to a piston 22 slidably mounted in each cylinder 21. Connected.

A timing rotor 51a having a plurality of teeth formed on a peripheral edge is attached to an end of the crankshaft 23, and an electromagnetic pickup 51b is attached to a cylinder block 1b near the timing rotor 51a. The timing rotor 51a and the electromagnetic pickup 51b constitute a crank position sensor 51.

A water temperature sensor 52 for outputting an electric signal corresponding to the temperature of the cooling water flowing in the cooling water passage 1c is attached to the cylinder block 1b.

Above the piston 22 of each cylinder 21, a combustion chamber 24 surrounded by the top surface of the piston 22 and the wall surface of the cylinder head 1a is formed. The cylinder head 1
a includes spark plugs 25 facing the combustion chamber 24 of each cylinder 21.
The ignition plug 25 is electrically connected to an igniter 25a for applying a drive current to the ignition plug 25.

In the cylinder head 1a, each cylinder 2
Two open ends of the intake port 26 and two open ends of the exhaust port 27 are formed at a portion facing one combustion chamber 24. And the cylinder head 1
In a, an intake valve 28 for opening and closing each open end of the intake port 26 and an exhaust valve 29 for opening and closing each open end of the exhaust port 27 are provided to be able to move forward and backward.

An electromagnetic drive mechanism 30 for driving the intake valve 28 forward and backward using an electromagnetic force generated when an exciting current is applied to the cylinder head 1a (hereinafter referred to as an intake-side electromagnetic drive mechanism 30). Are provided in the same number as the intake valves 28. Each intake side electromagnetic drive mechanism 30 has a drive circuit 30 for applying an exciting current to the intake side electromagnetic drive mechanism 30.
a (hereinafter referred to as an intake-side drive circuit 30a) is electrically connected.

An electromagnetic drive mechanism 31 for driving the exhaust valve 29 forward and backward by using an electromagnetic force generated when an excitation current is applied to the cylinder head 1a (hereinafter referred to as an exhaust-side electromagnetic drive mechanism 31). Are provided in the same number as the exhaust valves 29. Each exhaust-side electromagnetic drive mechanism 31 has a drive circuit 31 for applying an exciting current to the exhaust-side electromagnetic drive mechanism 31.
a (hereinafter, referred to as an exhaust-side drive circuit 31a) is electrically connected.

Here, a specific configuration of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 will be described.
The intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31
Since the configuration is the same as that described above, only the intake-side electromagnetic drive mechanism 30 will be described as an example.

FIG. 3 is a sectional view showing the structure of the intake-side electromagnetic drive mechanism 30. In FIG. 3, the cylinder head 1a of the internal combustion engine 1 includes a lower head 10 fixed to the upper surface of the cylinder block 1b, and an upper head 11 provided on the lower head 10.

The lower head 10 is provided with two intake ports 26 for each cylinder 21, and a valve body 28 a of an intake valve 28 is seated at an open end of each intake port 26 on the combustion chamber 24 side. A valve seat 12 is provided.

Each of the lower heads 10 has an intake port 2
A through-hole having a circular cross section is formed from the inner wall surface of 6 to the upper surface of the lower head 10, and a cylindrical valve guide 13 is inserted into the through-hole. A valve shaft 28b of the intake valve 28 penetrates through an inner hole of the valve guide 13, and the valve shaft 2
8b is slidable in the axial direction.

In the upper head 11, a portion where the axis is the same as that of the valve guide 13 is provided with a first core 30.
A core mounting hole 14 having a circular cross section into which the first and second cores 302 are fitted is provided. Lower part 1 of core mounting hole 14
4b is formed larger in diameter than its upper part 14a. Hereinafter, the lower part 14b of the core mounting hole 14 is referred to as a large diameter part 14b, and the upper part 14a of the core mounting hole 14 is referred to as a small diameter part 14a.

An annular first core 301 and a second core 302 made of a soft magnetic material are fitted in the small-diameter portion 14a in series in the axial direction with a predetermined gap 303 therebetween. At the upper end of the first core 301 and the lower end of the second core 302,
A flange 301a and a flange 302a are respectively formed, and the first core 301 is provided from above and the second core 3a.
The first core 301 and the second core 3 are respectively inserted into the core mounting holes 14 from below, and the flanges 301a and 302a abut against the edges of the core mounting holes 14.
02 is positioned, and the gap 303 is maintained at a predetermined distance.

An annular upper plate 318 is disposed above the first core 301, and the upper plate 3
18, the upper plate 3 is attached to the lower end of the cylindrical body.
An upper cap 305 formed with a flange 305a having an outer diameter substantially the same as that of the upper 18 is disposed.

The upper cap 305 and the upper plate 318 are connected to the flange 3 of the upper cap 305.
It is fixed to the upper surface of the upper head 11 by a bolt 304 that penetrates from the upper surface of the upper head 05a to the inside of the upper head 11 via the upper plate 318.

In this case, the lower end of the upper cap 305 including the flange 305a abuts on the upper surface of the upper plate 318, and the lower surface of the upper plate 318 Upper head 1 in contact with
1 and as a result, the first core 301
Is fixed to the upper head 11.

Below the second core 302, there is provided a lower plate 307 made of an annular body having an outer diameter substantially the same as the large diameter portion 14b of the core mounting hole 14. The lower plate 307 is fixed to a downward step surface in the step portion of the small diameter portion 14a and the large diameter portion 14b by a bolt 306 penetrating from the lower surface of the lower plate 307 to the upper head 11. In this case, the lower plate 307 is fixed while being in contact with the lower peripheral edge of the second core 302, and as a result, the second core 302 is fixed to the upper head 11.

A first electromagnetic coil 308 is held in a groove formed on the surface of the first core 301 on the side of the gap 303, and is formed on a surface of the second core 302 on the side of the gap 303. The second electromagnetic coil 309 is held in the groove. At this time, the first electromagnetic coil 308 and the second electromagnetic coil 309 are arranged at positions facing each other via the gap 303. The first and second electromagnetic coils 308 and 309 are electrically connected to the above-described intake side drive circuit 30a.

An armature 31 made of an annular body having an outer diameter smaller than the inner diameter of the gap 303 is provided in the gap 303.
1 is arranged. The armature 311 is formed of, for example, a soft magnetic material.

In the hollow portion of the armature 311, an armature shaft 310 made of a columnar non-magnetic material having an outer diameter smaller than the hollow portions of the first core 301 and the second core 302 is provided. It is fixed so as to extend vertically along the axis.

At this time, the armature shaft 310
Has its upper end reaching through the hollow portion of the first core 301 into the upper cap 305 above it, and its lower end passing through the hollow portion of the second core 302 into the large diameter portion 14b below it. It is formed as follows.

Correspondingly, each of the upper end of the hollow portion of the first core 301 and the lower end of the hollow portion of the second core 302 has an inner diameter substantially the same as the outer diameter of the armature shaft 310. An annular upper bush 319 and a lower bush 320 are provided.
The armature shaft 310 is slidably held in the axial direction by the lower bush 320 and the armature shaft 310.

A disc-shaped upper retainer 312 is joined to the upper end of the armature shaft 310 extending into the upper cap 305, and an adjust bolt 313 is screwed into the upper opening of the upper cap 305. An upper spring 314 is interposed between the upper retainer 312 and the adjustment bolt 313. A spring seat 315 having an outer diameter substantially equal to the inner diameter of the upper cap 305 is interposed on a contact surface between the adjust bolt 313 and the upper spring 314.

At the lower end of the armature shaft 310 extending into the large-diameter portion 14b, a valve shaft 28b of the intake valve 28 is provided.
Is in contact with the upper end. A disc-shaped lower retainer 28c is joined to the outer periphery of the upper end of the valve shaft 28b. A lower spring 316 is interposed between the lower surface of the lower retainer 28c and the upper surface of the lower head 10.

In the intake-side electromagnetic drive mechanism 30 configured as described above, when the excitation current is not applied to the first electromagnetic coil 308 and the second electromagnetic coil 309 from the intake-side drive circuit 30a, the upper Downward from the spring 314 relative to the armature shaft 310 (ie,
An urging force acts on the intake valve 28 (in a direction to open the intake valve 28), and an urging force acts on the intake valve 28 from the lower spring 316 in an upward direction (ie, a direction in which the intake valve 28 closes). As a result, the armature shaft 310
In addition, the state where the intake valve 28 abuts with each other and is elastically supported at a predetermined position, that is, a so-called neutral state is maintained.

The biasing force of the upper spring 314 and the lower spring 316 is set so that the neutral position of the armature 311 is located at an intermediate position between the first core 301 and the second core 302 in the gap 303. If the neutral position of the armature 311 is deviated from the above-described intermediate position due to an initial tolerance or a secular change of a component, the neutral position of the armature 311 is adjusted by the adjustment bolt 313 so as to match the above-described intermediate position. Has become possible.

The length of the armature shaft 310 and the valve shaft 28b in the axial direction is such that when the armature 311 is located at an intermediate position of the gap 303,
a becomes a middle position between the valve-opening-side displacement end and the valve-closing-side displacement end (hereinafter, referred to as a middle-open position), and when the armature 311 contacts the first core 301, the valve body 28
a is set to be seated on the valve seat 12.

In the above-described intake-side electromagnetic drive mechanism 30, when an excitation current is applied to the first electromagnetic coil 308 from the intake-side drive circuit 30a, the first core 301 and the first electromagnetic coil 308 are connected to each other. Since an electromagnetic force is generated between the armature 311 and the armature 311 to displace the armature 311 toward the first core 301, the armature 311 contacts the first core 301 against the urging force of the upper spring 314. Become.

When the armature 311 is in contact with the first core 301, the intake valve 28
6. The valve body 28a of the intake valve 28 retreats under the biasing force of
Is seated on the valve seat 12, that is, a fully closed state.

In the intake side electromagnetic drive mechanism 30, the second electromagnetic coil 309 is provided from the intake side drive circuit 30a.
When the exciting current is applied to the second core 30
Since an electromagnetic force is generated between the second and second electromagnetic coils 309 and the armature 311 in the direction of displacing the armature 311 toward the second core 302, the armature 311 resists the urging force of the lower spring 316. The two cores 302 come into contact with each other.

When the armature 311 is in contact with the second core 302, the armature shaft 310 presses the valve shaft 28b in the valve opening direction against the urging force of the lower spring 316, and the pressing force is applied. By the intake valve 28
Is held in the fully open state.

In the above-described intake-side electromagnetic drive mechanism 30, when the intake valve 28 in the fully closed state is opened, first, the intake-side drive circuit 30a stops applying the exciting current to the first electromagnetic coil 308. I do.

At this time, since the electromagnetic force for attracting the armature 311 to the first core 301 between the first core 301, the first electromagnetic coil 308, and the armature shaft 310 disappears, the armature 311 and the intake valve 28 are connected to the upper spring. The valve 314 is displaced in the valve opening direction by receiving the urging force of 314.

The intake side drive circuit 30a includes an armature 31
When the first electromagnetic coil 3 is displaced to the vicinity of the second core 302 by receiving the urging force of the upper spring 314, the second electromagnetic coil 3
By applying an exciting current to the second coil 302, an electromagnetic force that attracts the armature 311 to the second core 302 is generated between the second core 302, the second electromagnetic coil 309, and the armature 311. Armature 31 by this electromagnetic force
1 is displaced to a position where it comes into contact with the second core 302 (valve opening side displacement end), and as a result, the intake valve 28 is fully opened.

On the other hand, in the above-mentioned intake side electromagnetic drive mechanism 30, when closing the intake valve 28 in the fully open state, the intake side drive circuit 30a first stops applying the exciting current to the second electromagnetic coil 309. .

At this time, since the electromagnetic force for attracting the armature 311 to the second core 302 between the second core 302, the second electromagnetic coil 309, and the armature shaft 310 disappears, the armature 311 and the intake valve 28 become lower spring. It is displaced in the valve closing direction by receiving the urging force of 316.

The intake side drive circuit 30a includes an armature 31
The first core 3 receives the urging force of the lower spring 316
01, the first electromagnetic coil 30
8 by applying an exciting current to the first core 3.
01, the first electromagnetic coil 308, and the armature 311, an electromagnetic force for attracting the armature 311 to the first core 301 is generated. Armature 31 by this electromagnetic force
1 is displaced to a position where it comes into contact with the first core 301 (displacement end on the valve closing side). As a result, the valve body 28a of the intake valve 28 is
Sit on 2.

As described above, the intake side drive circuit 30a alternately applies the exciting current to the first electromagnetic coil 308 and the second electromagnetic coil 309 at a predetermined timing, whereby the armature 311 is displaced to the valve closing side. The reciprocating operation is performed between the end and the valve-opening-side displacement end, whereby the valve shaft 28b is driven to reciprocate and the valve body 28a opens and closes at the same time.
Therefore, the intake side drive circuit 30a is connected to the first electromagnetic coil 3
The opening and closing timing of the intake valve 28 can be arbitrarily controlled by changing the application timing of the exciting current to the second electromagnetic coil 08 and the second electromagnetic coil 309.

The intake side electromagnetic drive mechanism 30 has a valve lift sensor 3 for detecting the displacement of the intake valve 28.
17 are attached. This valve lift sensor 3
Reference numeral 17 denotes a disk-shaped target 317a attached to the upper surface of the applicator 312, and an adjustment bolt 31
3 and a gap sensor 317b attached to a portion facing the above-mentioned retainer 312.

In the valve lift sensor 317 thus configured, the target 317a is displaced integrally with the armature 311 of the intake side electromagnetic drive mechanism 30, and the gap sensor 317b is replaced by the gap sensor 317b.
An electrical signal corresponding to the distance between the target and the target 317a is output.

At this time, the output signal value of the gap sensor 317b when the armature 311 is in the neutral state is stored in advance, and the deviation between the output signal value and the current output signal value of the gap sensor 317b is calculated. Thereby, the displacement of the armature 311 and the intake valve 28 can be specified.

Returning to FIGS. 1 and 2, an intake branch pipe 33 composed of four branch pipes is connected to the cylinder head 1a of the internal combustion engine 1. Each branch pipe of the intake branch pipe 33 is connected to each cylinder. 21 and an intake port 26.

A fuel injection valve 32 is attached to the cylinder head 1a in the vicinity of the connection portion with the intake branch pipe 33 so that the injection hole faces the intake port 26.

The intake branch pipe 33 is connected to a surge tank 34 for suppressing the pulsation of the intake air. An intake pipe 35 is connected to the surge tank 34.
Is connected to an air cleaner box 36 for removing dust and dirt from the intake air.

The intake pipe 35 is provided with an air flow meter 44 for outputting an electric signal corresponding to the mass of the air flowing through the intake pipe 35 (mass of the intake air).
A throttle valve 39 for adjusting the flow rate of intake air flowing through the intake pipe 35 is provided at a position downstream of the air flow meter 44 in the intake pipe 35.

The throttle valve 39 includes a stepper motor or the like, and a throttle actuator 40 for opening and closing the throttle valve 39 according to the magnitude of the applied power.
And a throttle position sensor 41 for outputting an electric signal corresponding to the opening of the throttle valve 39.

The throttle valve 39 is rotatable independently of the throttle valve 39 and the accelerator pedal 4
An accelerator lever (not shown) that rotates in conjunction with 2 is attached to the accelerator lever, and an accelerator position sensor 43 that outputs an electric signal corresponding to the amount of rotation of the accelerator lever is attached to the accelerator lever.

On the other hand, the cylinder head 1 of the internal combustion engine 1
An exhaust branch pipe 45 formed so that four branch pipes merge into one collecting pipe immediately downstream of the internal combustion engine 1 is connected to a, and each branch pipe of the exhaust branch pipe 45 is connected to each cylinder 21. The exhaust port 27 communicates with the exhaust port 27.

The exhaust branch pipe 45 is connected to an exhaust pipe 47 via an exhaust purification catalyst 46, and the exhaust pipe 47 is connected downstream to a muffler (not shown). The exhaust branch pipe 4
5 is provided with an air-fuel ratio sensor 48 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust flowing in the exhaust branch pipe 45, in other words, the exhaust flowing into the exhaust purification catalyst 46.

Here, as the above-mentioned exhaust gas purifying catalyst 46, for example, hydrocarbons contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the exhaust gas purifying catalyst 46 is a predetermined air-fuel ratio near the stoichiometric air-fuel ratio (HC), carbon monoxide (CO), nitrogen oxides (NOx), a three-way catalyst, and nitrogen contained in the exhaust when the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 46 is a lean air-fuel ratio. When the air-fuel ratio of the exhaust gas flowing into the exhaust gas purifying catalyst 46 is a stoichiometric air-fuel ratio or a rich air-fuel ratio while the oxide (NOx) is being stored, the stored nitrogen oxides (NOx) are released and reduced and purified. When the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 46 is in an oxygen excess state and a predetermined reducing agent is present, nitrogen oxides (NOx) in the exhaust gas are reduced.
It is a selective reduction type NOx catalyst to be purified, or a catalyst obtained by appropriately combining the various catalysts described above.

The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 20 for controlling the operating state of the internal combustion engine 1.

The ECU 20 includes a throttle position sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, a crank position sensor 51, a water temperature sensor 52, and a valve lift sensor 3.
Various sensors such as 17 are connected via electric wiring, and output signals of each sensor are input to the ECU 20.

The ECU 20 includes an igniter 25a,
The intake-side drive circuit 30a, the exhaust-side drive circuit 31a, the fuel injection valve 32, the throttle actuator 40, and the like are connected via electric wiring, and the ECU 20 sets the igniter 25
a, the intake side drive circuit 30a, the exhaust side drive circuit 31a, the fuel injection valve 32, or the throttle actuator 40
Can be controlled.

Here, as shown in FIG. 4, the ECU 20 connects the CPs connected by a bidirectional bus 400 to each other.
It has a U 401, a ROM 402, a RAM 403, a backup RAM 404, an input port 405 and an output port 406, and has an A / D converter (A / D) 407 connected to the input port 405.

The A / D 407 includes a throttle position sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, and a water temperature sensor 5.
2. It is connected to a sensor that outputs a signal in the form of an analog signal, such as a valve lift sensor 317, via electric wiring. The A / D 407 converts the output signal of each sensor from an analog signal format to a digital signal format, and then transmits the converted signal to the input port 405.

The input port 405 outputs a signal in the form of an analog signal, such as the above-described throttle position sensor 41, accelerator position sensor 43, air flow meter 44, air-fuel ratio sensor 48, water temperature sensor 52, valve lift sensor 317, and the like. Sensor and A / D40
7 and is connected to a sensor that outputs a signal in digital signal format, such as a crank position sensor 51.

The input port 405 inputs the output signals of various sensors directly or via the A / D 407, and outputs those output signals via the bidirectional bus 400 to the CPU 401.
Or to the RAM 403.

The output port 406 is connected to the igniter 25
a, the intake-side drive circuit 30a, the exhaust-side drive circuit 31a, the fuel injection valve 32, the throttle actuator 40, and the like are connected via electric wiring. The output port 406
Receives a control signal output from the CPU 401 via the bidirectional bus 400 and transmits the control signal to the igniter 2.
5a, an intake side drive circuit 30a, an exhaust side drive circuit 31a,
Fuel injection valve 32 or throttle actuator 40
Send to

The ROM 402 includes a fuel injection amount control routine for determining the fuel injection amount, a fuel injection timing control routine for determining the fuel injection timing, and an intake valve opening / closing timing for determining the opening / closing timing of the intake valve 28. A control routine, an exhaust valve opening / closing timing control routine for determining the opening / closing timing of the exhaust valve 29, an intake side exciting current control routine for determining an exciting current amount to be applied to the intake side electromagnetic drive mechanism 30, and an exhaust side electromagnetic drive Exhaust-side excitation current amount control routine for determining the amount of excitation current to be applied to the mechanism 31; ignition timing control routine for determining the ignition timing of the spark plug 25 of each cylinder 21;
In addition to an application program such as a throttle opening control routine for determining the opening of the internal combustion engine 9, a startup valve timing control routine for controlling the opening / closing timing of the intake and exhaust valves 28 and 29 when the internal combustion engine 1 is started is stored. are doing.

[0086] The ROM 402 stores various control maps in addition to the application programs described above. The control map includes, for example, a fuel injection amount control map indicating a relationship between the operating state of the internal combustion engine 1 and the fuel injection amount, a fuel injection timing control map indicating a relationship between the operating state of the internal combustion engine 1 and the fuel injection timing, An intake valve opening / closing timing control map showing the relationship between the operating state of the internal combustion engine 1 and the opening / closing timing of the intake valve 28, the operating state of the internal combustion engine 1 and the exhaust valve 2
Exhaust valve opening / closing timing control map showing the relationship between the opening / closing timing of FIG. 9 and the intake side exciting current amount control map showing the relationship between the operating state of the internal combustion engine 1 and the amount of exciting current to be applied to the intake side electromagnetic drive mechanism 30 An exhaust-side exciting current control map showing the relationship between the operating state of the engine 1 and the amount of exciting current to be applied to the exhaust-side electromagnetic drive mechanism 31, and the relationship between the operating state of the internal combustion engine 1 and the ignition timing of each spark plug 25. And a throttle opening control map indicating the relationship between the operating state of the internal combustion engine 1 and the opening of the throttle valve 39.

The RAM 403 stores the output signal of each sensor, the calculation result of the CPU 401, and the like. The calculation result is, for example, an engine speed calculated based on an output signal of the crank position sensor 51. The RAM
Various data stored in 403 is updated to the latest data every time the crank position sensor 51 outputs a signal.

The backup RAM 404 is a non-volatile memory that retains data even after the operation of the internal combustion engine 1 is stopped, and stores a learning value relating to various controls, information for specifying a location where an abnormality has occurred, and the like.

The CPU 401 operates in accordance with the application program stored in the ROM 402, and includes, in addition to well-known controls such as fuel injection control, ignition control, intake valve opening / closing control, exhaust valve opening / closing control, throttle control, etc., the gist of the present invention. Start valve timing control is performed as follows.

Hereinafter, the valve timing control at the time of starting according to the present embodiment will be described. In the so-called cranking period from the start of the start of the internal combustion engine 1 to the completion of the start of the internal combustion engine 1, during the cranking period until the first explosion (first explosion) occurs, as shown in FIG. The intake and exhaust valves 28, 2 are so set that the valve overlap period between the intake valve 28 and the exhaust valve 29 is extremely short.
9 is set to open / close timing.

This is because when the amount of valve overlap between the intake valve 28 and the exhaust valve 29 increases during the cranking period before the first explosion occurs, the fresh air flowing into the combustion chamber 24 from the intake port 26 of each cylinder 21 This is because the fuel easily flows back to the exhaust port 27 and causes problems such as a decrease in the compression pressure and an insufficient amount of fuel, which may make it difficult to cause an explosion.

Subsequently, when the CPU 401 detects the initial explosion when the internal combustion engine 1 is started, as shown in FIG. 6, the valve overlap amounts of the intake and exhaust valves 28 and 29 are reduced for the cylinder 21 in which the initial explosion has occurred. The opening and closing timings of the intake and exhaust valves 28 and 29 are changed so as to increase as compared to before the first explosion occurs.

At this time, if the valve opening start timing of the intake valve 28 is excessively advanced, the amount of exhaust remaining in the combustion chamber 24 becomes excessive, and the fresh air sucked into the combustion chamber 24 and Since the amount of fuel may be too small, the valve overlap amount is increased by increasing the retard amount at the closing end timing of the exhaust valve 29 with respect to the advance amount at the opening start timing of the intake valve 28. Preferably, it is increased.

When the valve overlap amount of the first-explosion-causing cylinder 21 is increased as described above, a part of the air-fuel mixture (burned air-fuel mixture) burned in the combustion chamber 24 of the first-explosion-occurring cylinder 21 is taken in by the intake air. It flows back to the intake branch pipe 33 through the port 26.

The burned mixture that has flowed back into the intake branch pipe 33 heats fresh air in the intake branch pipe 33 by the heat of the burned mixture. The fresh air heated in the intake branch pipe 33 is supplied to each cylinder 2
The air is distributed to one intake port 26 and then supplied to the combustion chamber 24 of each cylinder 21.

In this case, the ambient temperature in the combustion chamber 24 of each cylinder 21 increases. Further, when heated fresh air passes through the intake port 26 of each cylinder 21, the fuel injection valve 32
When the fuel is injected from the fuel, atomization of the fuel is promoted, and the fresh air and the fuel are easily mixed homogeneously.

As a result, the combustion chamber 24 of each cylinder 21 has:
A highly flammable mixture is supplied, and each cylinder 2
In 1, the explosion is likely to occur. In particular, when the highly flammable air-fuel mixture as described above is supplied to the cylinders 21 other than the cylinder 21 in which the first explosion occurs, an explosion easily occurs in those cylinders 21, so that the time required for starting the internal combustion engine 1 is increased. Can be shortened.

On the other hand, in the normal fuel injection control, when the internal combustion engine 1 is in the operating state, the intake synchronous injection synchronized with the opening timing of the intake valve 28 is performed, and when the internal combustion engine 1 is cold started. As shown in FIG. 7, in order to prevent fuel from adhering to the spark plug 25, asynchronous intake injection is performed asynchronously with the opening period of the intake valve 28 (intake valve 2).
One or more fuel injections are performed during the valve closing period of No. 8).

On the other hand, in the fuel injection control according to the present embodiment, the CPU 401 performs the above-described asynchronous intake air injection during the cranking period from the start of the internal combustion engine 1 to the occurrence of the first explosion. In the cranking period, as shown in FIG. 8, fuel injection is performed from the middle of the valve opening period of the exhaust valve 29 to the middle of the valve overlap period for the cylinder 21 in which the explosion has occurred.

As described above, when fuel is injected during the valve overlap period of the cylinder 21 in which the explosion has occurred, the fuel injected from the fuel injection valve 32 relatively flows back from the combustion chamber 24 to the intake port 26. Since it is exposed to high-temperature exhaust gas, atomization of fuel in the cylinder 21 in which the explosion has occurred is suitably promoted, and combustion of the cylinder 21 is stabilized.

When the internal combustion engine 1 is cold started, fuel injected from the fuel injection valve 32 is supplied to the intake port 26 or the combustion chamber 2.
The fuel injection amount is increased and corrected in anticipation of such a wall-attached fuel amount because it easily adheres to the wall surface such as the fourth, but the heat of the exhaust of the first-explosion generating cylinder 21 is utilized as described above. When the atomization of fuel is promoted, the amount of fuel adhering to the wall decreases, so that it is possible to suppress the increase correction of the fuel injection amount,
Thus, the fuel consumption at the time of starting the internal combustion engine 1 can be reduced.

In the above-described valve timing control at the time of starting, the valve overlap amount of the intake and exhaust valves 28 and 29 is increased during the cranking period from the occurrence of the first explosion to the completion of the starting, but continues after the completion of the starting. Intake and exhaust valves 28,2
The warm-up of the internal combustion engine 1 may be promoted by increasing the valve overlap amount of No. 9.

Next, the starting valve timing control according to the present embodiment will be specifically described.

In executing the valve timing control at the time of starting, the CPU 401 executes a valve timing control routine at the time of starting as shown in FIG. This start-time valve timing control routine is a routine stored in the ROM 402 in advance.
This is a routine that is executed by using the start of the start of the program as a trigger.

In the starting valve timing control routine, the CPU 401 first determines in S901 whether or not the internal combustion engine 1 is in the starting state. As a specific method of determining whether or not the internal combustion engine 1 is in a starting state,
A method of determining based on whether or not a starter switch (not shown) is in an on state (whether or not a starter motor is in an operating state) can be exemplified.

When it is determined in S901 that the internal combustion engine 1 is not in the starting state, the CPU 401 ends the execution of this routine.

If it is determined in S901 that the internal combustion engine 1 is in the starting state, the CPU 401 proceeds to S90.
Proceeding to 2, the output signal value of the water temperature sensor 52 is read, and it is determined whether the output signal value of the water temperature sensor 52 is lower than a predetermined temperature.

If it is determined in step S902 that the output signal value of the water temperature sensor 52 is equal to or higher than the predetermined temperature, the CPU 401 determines that the internal combustion engine 1 is started in a warm state, and proceeds to step S909.

In step S909, the CPU 401 determines that the valve overlap between the intake valve 28 and the exhaust valve 29 has occurred during the entire cranking period from the start of the start of the internal combustion engine 1 to the explosion (complete explosion) in all the cylinders 21. The intake-side drive circuit 30a and the exhaust-side drive circuit 31a are controlled so that the amounts are extremely small. That is, when the internal combustion engine 1 is warm-started, the CPU 401 performs the valve timing control as described above with reference to FIG. 5 throughout the entire cranking period from the start of the internal combustion engine 1 to the completion of the start.

On the other hand, at S902, the water temperature sensor 5
When it is determined that the output signal value of No. 2 is lower than the predetermined temperature, the CPU 401 determines that the internal combustion engine 1 is started in a cold state, and proceeds to S903.

In S903, the CPU 401 determines that the intake valve 2
The valve timing of the intake valve 28 and the exhaust valve 29 is set so that the valve overlap amount between the valve 8 and the exhaust valve 29 is extremely small, and the intake side drive circuit 30a and the exhaust side drive circuit 31a are controlled according to the set valve timing. .

In S904, the CPU 401 determines whether or not the first explosion (first explosion) has occurred in any one of the four cylinders 21 of the internal combustion engine 1. Internal combustion engine 1
As a method for determining whether or not the first explosion has occurred, the amount of change in the engine speed immediately after the ignition timing of each cylinder 21 (for example, in the period from compression top dead center to 30 ° CA after compression top dead center). It is possible to exemplify a method of determining whether or not the first explosion has occurred based on the amount of change in the engine speed.

If it is determined in S904 that the first explosion has not occurred, the CPU 401 proceeds to S903.
Execute the subsequent processing again.

If it is determined in S904 that the first explosion has occurred, the CPU 401 proceeds to S905. S
In 905, the CPU 401 increases the valve overlap amount of the intake valve 28 and the exhaust valve 29 of the cylinder 21 in which the initial explosion has occurred, as described in the description of FIG. It controls the intake-side drive circuit 30a and the exhaust-side drive circuit 31a of the first-explosion cylinder 21.

In S906, it is determined whether or not an explosion has occurred in the cylinders 21 other than the cylinder 21 in which the initial explosion has occurred.

If it is determined in step S906 that no explosion has occurred in any of the cylinders 21 other than the cylinder 21 in which the initial explosion has occurred, the CPU 401 executes the processing from step S905 again.

If it is determined in S906 that an explosion has occurred in any of the cylinders 21 other than the cylinder 21 in which the first explosion has occurred,
The PU 401 proceeds to S 907, and the explosion-occurring cylinder 21
In order to increase the amount of valve overlap between the intake valve 28 and the exhaust valve 29 of the explosion-causing cylinder 21 before the occurrence of the explosion,
Of the intake-side drive circuit 30a and the exhaust-side drive circuit 31a.

In S908, the CPU 401 determines whether or not an explosion has occurred in all the cylinders 21 of the internal combustion engine 1, that is, whether or not all the cylinders 21 of the internal combustion engine 1 have completely exploded. In S908, all the cylinders 21 of the internal combustion engine 1
If it is determined that has not completely exploded, the CPU 401
Deems that the start of the internal combustion engine 1 has not been completed, and repeatedly executes the processing after S906.

If it is determined in S908 that all cylinders 21 of the internal combustion engine 1 have completely exploded, the CPU 401
Ends the execution of this routine, in other words, the execution of the valve timing control at the time of starting.

As described above, when the CPU 401 executes the start-time valve timing control routine, the initial explosion occurs at the time of the cold start of the internal combustion engine 1 and the internal combustion engine 1 is operated at a lower level than before the initial explosion occurs. The amount of exhaust gas flowing backward to the intake system can be increased, and the valve operating mechanism control means according to the present invention is realized. As a result, it is possible to increase the intake air temperature of the internal combustion engine 1 after the first explosion has occurred, and it is possible to reduce the time required for starting the internal combustion engine 1.

Further, according to the valve timing control at the time of starting according to the present embodiment, the internal combustion engine 1 after the first explosion occurs.
Therefore, by injecting fuel from the fuel injection valve 32 into such high-temperature intake air, atomization of the fuel can be promoted. As a result, after the first explosion occurs, a highly flammable air-fuel mixture can be supplied to each of the cylinders 21 of the internal combustion engine 1, so that the ignitability of the air-fuel mixture in the cylinders 21 other than the first explosion-occurring cylinder 21 is improved. As a result, the time required for starting the internal combustion engine 1 can be reduced.

In the present embodiment, an intake port injection type internal combustion engine in which fuel is injected into the intake port has been described as an example. However, the present invention is not limited to this. An in-cylinder direct injection type internal combustion engine that directly injects fuel into the engine may be used. Even when the present invention is applied to an in-cylinder direct injection type internal combustion engine, it is possible to increase the intake air temperature of the internal combustion engine, so that fuel is atomized when fuel is injected into each cylinder. Therefore, the time required for starting the internal combustion engine can be reduced.

<Other Embodiments> In the above-described embodiment, when the internal combustion engine 1 is cold started, during the cranking period after the first explosion occurs, the valve over of each cylinder 21 follows the order in which the explosions occurred. Although the example in which the lap amount is increased has been described, in the cranking period after the first explosion occurs, the lift amount of the intake valve 28 at the time of valve overlap of each cylinder 21 may be increased in accordance with the order in which the explosions occurred. Preferably, as shown in FIG. 10, the amount of valve overlap of the cylinder 21 in which the explosion has occurred is increased, and at the same time, the intake valve 28 at the time of valve overlap is increased.
It is preferable to increase the lift amount of the vehicle. In short, during the cranking period after the first explosion, the cylinder 2 where the explosion occurred
It is sufficient that the burned air-fuel mixture easily flows back to the intake system of the internal combustion engine 1 in 1.

[0124]

According to the control apparatus for a variable valve mechanism for an internal combustion engine according to the present invention, the amount of exhaust gas flowing back into the intake system of the internal combustion engine after the initial explosion occurs, compared to before the initial explosion occurs. Therefore, it is possible to increase the intake air temperature of the internal combustion engine after the first explosion has occurred, and as a result, it is possible to shorten the time required for starting the internal combustion engine when it is cold started.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of an internal combustion engine according to the present invention.

FIG. 2 is a sectional view showing a schematic configuration of an internal combustion engine according to the present invention.

FIG. 3 is a diagram showing an internal configuration of an intake-side electromagnetic drive mechanism.

FIG. 4 is a block diagram showing an internal configuration of an ECU.

FIG. 5 is a timing chart showing a valve timing of a cylinder before an explosion occurs when the internal combustion engine is started.

FIG. 6 is a timing chart showing the valve timing of a cylinder after an explosion has occurred at the time of starting the internal combustion engine.

FIG. 7 is a timing chart showing a fuel injection timing of a cylinder before an explosion occurs when the internal combustion engine is started.

FIG. 8 is a timing chart showing fuel injection timing of a cylinder after an explosion has occurred at the time of starting the internal combustion engine.

FIG. 9 is a flowchart showing a start-time valve timing control routine.

FIG. 10 is a timing chart showing valve timing and valve lift of a cylinder after an explosion has occurred at the time of starting the internal combustion engine.

[Explanation of symbols]

 1 Internal combustion engine 20 ECU 25 Spark plug 26 Intake port 27 Exhaust port 28 Intake valve 29 Exhaust valve 30 ... intake side electromagnetic drive mechanism 30a ... intake side drive circuit 31 ... exhaust side electromagnetic drive mechanism 31a ... exhaust side drive circuit 32 ... fuel injection valve 401 ... CPU 402 ..ROM

Continued on the front page F term (reference) 3G018 AA06 AB09 AB16 BA38 CA12 DA36 DA38 DA41 DA66 DA69 DA83 EA11 EA17 EA21 EA22 EA31 EA32 EA35 FA01 FA06 FA07 FA09 GA11 3G092 AA01 AA05 AA11 AB02 DA01 DA02 DA07 DG09 EA01 HA01 GA01 EC02 HA13X HA13Z HE01Z HE02Z HE03Z HE08Z HF08Z 3G301 HA01 JA00 KA01 LC01 ND01 NE01 NE06 PA01Z PA07Z PA11Z PE01Z PE02Z PE03Z PE08Z PE10A PE10Z PF03Z

Claims (4)

[Claims] A variable valve mechanism capable of changing an opening / closing timing and / or a lift of at least one of an intake valve and an exhaust valve of the internal combustion engine; A valve mechanism control means for controlling the variable valve mechanism so that the amount of exhaust flowing back to the intake system of the engine increases compared to before the occurrence of the first explosion. Control device. 2. A variable valve mechanism for changing at least one of an intake valve and an exhaust valve of an internal combustion engine, the opening / closing timing and / or the lift amount of the internal combustion engine. A valve operating mechanism control means for controlling the variable valve operating mechanism so that the valve overlap amount between the exhaust valve and the exhaust valve increases before the first explosion occurs. Control device. 3. A variable valve mechanism capable of changing at least one of an intake valve and an exhaust valve of an internal combustion engine, that is, an opening / closing timing and / or a lift amount. And valve operating mechanism control means for controlling the variable valve operating mechanism such that the lift amount of the intake valve at the time of valve overlap between the valve and the exhaust valve increases compared to before the first explosion. A control device for a variable valve mechanism for an internal combustion engine. 4. The variable valve mechanism according to claim 1, wherein the variable valve mechanism is an electromagnetically driven valve mechanism that opens and closes an intake valve and / or an exhaust valve using an electromagnetic force. The control device for a variable valve mechanism for an internal combustion engine according to any one of the preceding claims.