JP2001295673A - Internal combustion engine having split intake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine which is improved in combustion and volume efficiency of intake air by dividing an intake system into a main intake system and a sub-intake system, and varying the pressure of the sub-intake system and the opening and closing time of the sub-intake valve. SOLUTION: This intake system is provided with plural intake ports, at least one of them being an intake port 7a of the main intake system opened and closed by a main intake valve 70a, a fuel feeder is mounted in the intake port 7a of the main intake system, at least another port being an intake port 7b of the sub-intake system opened and closed by a sub-intake valve 70b. The intake port 7b of the sub-intake system is connected to a pressure air supply passage 27 having a supercharger 10, and the sub-intake valve 70b opens the intake port 7b, in the latter half of the exhaust stroke and/or the latter half of the intake stroke, and the operation thereof can be stopped by a stopping mechanism.

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 having a split intake system, and more particularly to an engine for improving combustion at the time of a cold start and a high load.

[0002]

2. Description of the Related Art Conventionally, a sub-intake system is provided in addition to a normal intake system, and pressurized air is supplied from an auxiliary intake system into a cylinder from an exhaust stroke to an intake stroke of an internal combustion engine. A forced scavenging engine equipped with an air pump as a source is known from JP-A-53-86918. The purpose of this forced scavenging engine is to drive out residual gas by supplying pressurized air into the cylinder from the exhaust stroke to the intake stroke of the engine, to increase the intake amount of fresh air, and to improve the output of the engine. I have.

[0003] The above apparatus focuses on the engine intake air amount and the residual gas ratio in the cylinder, and operates according to the operating state of the engine so that scavenging air can be supplied appropriately in response to the fluctuation of the residual gas. ing. Therefore, a flow control valve is provided which accumulates the discharge air of the air pump in a surge tank and proportionally reduces the pressure of the air in the surge tank via a pressure regulator to supply the air to a sub intake system.

[0004]

However, the above-described conventional forced scavenging engine only aims to drive out residual gas from the cylinder, and the sub intake system always controls the flow rate from the exhaust stroke to the intake stroke of the internal combustion engine. Pressurized air is supplied into the cylinder via a valve.

Therefore, there is a problem that the air-fuel ratio of the exhaust gas becomes excessive in the scavenging of the residual gas and the amount of generated NOx increases. Further, although the air flow rate is adjusted by the supply of the pressurized air, the supply of the pressurized air is always performed at a certain time from the exhaust stroke to the intake stroke.

However, when the internal combustion engine is warmed up, and when the load is low, the necessity of operating the flow control valve of the auxiliary intake system is reduced. In such a case, the above-described viewpoint of reducing NOx is also required. It is desirable to stop the operation of the flow control valve.

On the other hand, by controlling the operation timing of the flow control valve, a variety of measures can be taken in accordance with the operating conditions. For example, if fresh air can be supplied to the auxiliary intake system not only from the exhaust stroke to the intake stroke, but also in the latter half of the intake stroke, the combustion at cold start can be improved, or the volumetric efficiency of the intake air volume at high load can be improved. Output improvement can be expected. However, in the above-mentioned conventional apparatus, it is impossible to stop the operation of the flow control valve and to change the opening / closing timing.
No. 918 does not disclose.

The present invention has been made in view of such circumstances, and provides an internal combustion engine capable of improving combustion and improving volumetric efficiency by changing the pressure of a sub intake system and the opening / closing timing of a sub intake valve. That is the task.

[0009]

The present invention has the following configuration to achieve the above object. That is, a plurality of intake ports are provided, at least one of which is a main intake system intake port that is opened and closed by a main intake valve, and a fuel supply device is installed in the main intake system intake port, and at least the other is provided. One is an intake port of an auxiliary intake system that is opened and closed by an auxiliary intake valve, and the intake port of the auxiliary intake system is connected to a pressurized air supply passage provided with a supercharger. And / or The opening of the intake port in the latter half of the intake stroke, and the operation can be stopped by the stop mechanism.

In the present invention, since the intake by the sub intake valve is added to the intake by the main intake valve, it is necessary to make the opening states of the intake valve and the exhaust valve overlap in order to improve the intake efficiency as in the prior art. Therefore, there is no need to overlap the open states of the main intake valve and the exhaust valve. At this time, by delaying the opening timing of the main intake valve, it is possible to prevent the fuel in the cylinder from flowing into the exhaust system, and at the same time, prevent the residual gas in the cylinder from returning to the intake system.

However, the opening timing of the main intake valve may be set to a conventional timing. Further, in the present invention, a variable valve mechanism for adjusting the opening / closing timing of the auxiliary intake valve can be provided. With this variable valve mechanism,
More appropriate intake control according to the driving situation becomes possible.

The supercharger may be any one which can supply supercharged air of a constant pressure, and may be a known one such as an air pump, a turbocharger or a supercharger, and is particularly limited. is not.

In the present invention, the auxiliary intake valve has a stop mechanism,
It can only be activated when necessary. For example, at the time of a cold start (for example, when the water temperature is 40 ° C. or less), the auxiliary intake valve is opened, and fresh air is supplied in the latter half of the exhaust stroke and the latter half of the intake stroke, thereby causing intake turbulence in the cylinder and combustion. Can be improved. At this time, since the air-fuel ratio of the exhaust gas increases, unburned HC burns. Then, the temperature of the exhaust gas rises, and the warm-up property of the catalyst provided in the exhaust passage is improved.

By opening the auxiliary intake valve at high load (at full load), when fresh air is introduced into the cylinder in the latter half of the intake stroke, volumetric efficiency is improved and engine output is increased. Can be Then, when fresh air is introduced into the cylinder in the latter half of the exhaust stroke, the air-fuel ratio of the exhaust gas increases, as described above, so that unburned HC burns and the exhaust gas temperature rises. Performance is improved.

Further, since the exhaust gas after combustion is forcibly scavenged by introducing fresh air, so-called knocking can be suppressed. In this case, in principle, it is not necessary to independently control the opening / closing timing in the latter half of the exhaust stroke and the opening / closing timing in the latter half of the intake stroke for the auxiliary intake valve. However, assuming that these can be controlled independently, regarding the operation of the auxiliary intake valve that opens and closes in the latter half of the intake stroke, the auxiliary intake valve always opens and closes even while the latter half of the exhaust stroke is stopped by the stop mechanism. Good. In this case, the intake air is constantly disturbed and the combustion is improved, which leads to an improvement in output.

In the case where a variable valve mechanism for adjusting the opening / closing timing of the sub intake valve is provided, the opening timing of the sub intake valve in the latter half of the intake stroke is set earlier when the engine is running at a low speed and later when the engine is running at a high speed. The effect of improving the volumetric efficiency is increased.

By the variable valve mechanism, when the opening timing of the auxiliary intake valve in the latter half of the exhaust stroke is advanced when the internal combustion engine is cold, combustion in the chamber is promoted, and the engine rotates at high load under high load. Sometimes by opening the valve earlier,
The scavenging effect can be increased.

In the present invention, the operation of the auxiliary intake valve can be stopped by the auxiliary intake valve stop mechanism as described above, except when necessary, especially when the load is low, so that fresh air is generated in the latter half of the exhaust stroke as in the prior art. As a result of the air being always introduced and the air-fuel ratio of the exhaust gas becoming lean, a situation in which a large amount of NOx is generated is avoided.

The operation stop of the auxiliary intake valve by the stop mechanism and the adjustment of the opening / closing timing by the variable valve mechanism can be easily achieved by operating the auxiliary intake valve by the electromagnetic drive mechanism.
Other known intake and exhaust valve stop mechanisms and variable valve operating mechanisms can be employed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of an internal combustion engine having a split intake system according to the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a schematic configuration of an internal combustion engine according to the present invention, and FIG. 2 is a plan view thereof. The internal combustion engine 1 is a four-cycle gasoline engine, includes a plurality of cylinders 2, a plurality of cylinders 2, and a cooling water passage 1.
The cylinder block 1b has a cylinder head 1a fixed to an upper portion of the cylinder block 1b.

A crankshaft 4 as an engine output shaft is rotatably supported on the cylinder block 1b. The crankshaft 4 is connected to a piston 3 slidably mounted in each cylinder 2. .

Above the piston 3, a combustion chamber 5 surrounded by a top surface of the piston 3 and a wall surface of the cylinder head 1a is provided.
Are formed. An ignition plug 6 is attached to the cylinder head 1 a so as to face the combustion chamber 5.
Is connected to an igniter 6a for applying a drive current to the ignition plug 6.

The cylinder head 1a is formed such that the open ends of two intake ports 7a and 7b and the open ends of two exhaust ports 8 face the combustion chamber 5. The opening ends of the intake ports 7a, 7b and the exhaust port 8a are connected to a main intake valve 70 supported by the cylinder head 1a so as to be able to move forward and backward.
a, which is opened and closed by the sub intake valve 70b and the exhaust valve 80; The main intake valve 70a is provided by the intake camshaft 11 rotatably supported by the cylinder head 1a, and the sub intake valve 70b is provided by the camshaft 12.
Each is driven forward and backward. The exhaust valve 80 is driven forward and backward by an exhaust camshaft (not shown).

The main intake system is provided with a fuel injection valve 9 for injecting fuel into each cylinder 2 in the intake port 7 of the main intake system, while the intake port 7b of the sub intake system is provided with The pressurized air supply passage 27 in which the supercharger 10 is arranged is connected. Although the supercharger 10 is an air pump and has a constant supercharging pressure, the supercharging pressure may be changed according to the engine speed or load (negative pressure in the intake pipe). That is, when the engine speed increases and the load increases, the supercharging pressure may be increased in synchronization with these.

In this embodiment, the main intake valve 70a and the sub intake valve 70b of the intake system are provided one by one for each cylinder 2. However, the number of intake and exhaust valves is not particularly limited. Instead, for example, as shown in FIG. 5, the intake system may be configured to have two main intake valves and one auxiliary intake valve.

The intake camshaft 11, the camshaft 12, and the exhaust camshaft (not shown) are connected to the crankshaft 4 via a timing belt (not shown), and the rotation of the crankshaft 4 is controlled by the intake belt via the timing belt. It is transmitted to the side camshaft 11, the camshaft 12, and the exhaust side camshaft.

The auxiliary intake valve 70b can be stopped by the following stop mechanism. As the stop mechanism, for example, a mechanism including a camshaft 12 and a rocker arm that operates a sub intake valve 70b having a built-in hydraulic piston can be adopted. When the hydraulic piston is not operated by hydraulic pressure, the rocker arm is disconnected from the camshaft 12 and continues to swing without opening and closing the auxiliary intake valve 70b. A valve provided in a hydraulic circuit of the hydraulic piston is provided with an electronic control unit (Electronic Control Unit) for controlling an operation state of the internal combustion engine 1.
ol Unit: ECU (hereinafter, referred to as ECU). When oil flows into the piston and is pressurized, the rocker arm and the camshaft 12 are connected to each other by a pin by the movement of the piston, and the opening and closing operation of the sub intake valve 70b is started. The operation and stop of the sub intake valve 70b can be controlled by such a mechanism.

In order to arbitrarily stop the auxiliary intake valve 70b, the camshaft 1
It does not operate in synchronization with the rotation of the crankshaft 4 and operates in synchronization with the rotation of the crankshaft 4. The operation and stop of the valve can be freely controlled at any time. The electromagnetically driven valve is provided with an electromagnetically driven valve mechanism that opens and closes the intake valve using a magnetic force. That is, at least the auxiliary intake valve 70
As a mechanism for operating b, an electromagnetic drive mechanism for driving the sub intake valve 70b by an electromagnet provided on the cylinder head 1a can be employed.

As for at least the auxiliary intake valve 70b, an electromagnetic drive mechanism can be employed as a means for controlling the opening / closing timing as described later and for easily realizing the operation stop by the stop mechanism. It is.

Here, a specific configuration of an electromagnetic drive mechanism that can be employed for the sub intake valve 70b will be described. FIG. 3 is a sectional view showing the configuration of the electromagnetically driven valve on the auxiliary intake side. In the drawing, a cylinder head 1a of an internal combustion engine 1 includes a lower head 110 fixed to an upper surface of a cylinder block 1b, and an upper head 111 provided on an upper portion of the lower head 110.
And

The lower head 110 has an intake port 7b.
Is formed at the opening end of the intake port 7b on the side of the combustion chamber 5, the valve seat 120 on which the valve body 700 of the sub intake valve 70b is seated.
Is provided.

The lower head 110 is formed with a through hole 704 having a circular cross section from the inner wall surface of the intake port 7b to the upper surface of the lower head 110. The through hole 704 guides the valve shaft 701 of the sub intake valve 70b to be able to move forward and backward. A cylindrical valve guide 112 is inserted.

The upper head 111 includes a first core 301.
A core mounting hole 114 having a circular cross section into which the second core 302 is fitted is provided. In the core mounting hole 114, an annular first core 301 and a second core 302 made of a soft magnetic material are provided with a predetermined gap 303. Are inserted in series in the axial direction.

Further, a cylindrical upper cap 305 is provided above the first core 301, and is fixed to the upper surface of the upper head 11 by passing a bolt 304 through a flange portion 305a formed at the lower end thereof. At this time, the lower end of the upper cap 305 including the flange portion 305a abuts on the peripheral edge of the upper surface of the first core 301, and by holding this, the first core 301 is fixed to the upper head 11.

On the other hand, an annular lower cap 307 is provided below the second core 302, and a bolt 30
6 penetrates and is fixed to the downward step surface in the step portion of the small diameter portion 14a and the large diameter portion 14b. At this time, the lower cap 307 abuts on the lower peripheral edge of the first core 302 and holds the lower core 307 so that the first core 301 can move the upper head 11.
Fixed to

A first electromagnetic coil 308 is mounted in a groove formed on the surface of the first core 301 on the side of the gap 303, while the same is provided on the surface of the second core 302 on the side of the gap 303. , A second electromagnetic coil 309 is mounted thereon, and the first electromagnetic coil 308 and the second electromagnetic coil 30
9 are arranged facing each other.

An annular armature 311 made of a soft magnetic material is arranged in the middle of the gap 303. The upper end of the armature 311 extends vertically from the center of the armature 311 to the inside of the upper cap 305 through the center of the first core 301, and the lower end of the upper core 305 of the second core 302. A columnar armature shaft 310 is provided to pass through the center and into the large-diameter portion 14b below the armature shaft 310. The armature shaft 310 is held so as to be able to advance and retreat in the axial direction.

A disc-shaped upper retainer 312 is joined to the base end of the armature shaft 310 extending into the upper cap 305, and an adjust bolt 313 is screwed into an upper opening of the upper cap 305. An upper spring 314 is interposed between the upper retainer 312 and the adjustment bolt 313.

On the other hand, the distal end of the armature shaft 310 extending into the large diameter portion 12b is in contact with the base end 702 of the valve shaft 701 of the sub intake valve 70b. This base end 7
A disc-shaped lower retainer 703 is joined to the outer periphery of the lower head 02 and the lower head 1 and the lower head 1.
A lower spring 316 is interposed between the upper spring 10 and the upper surface of the lower spring 10.

In the electromagnetic drive mechanism on the auxiliary intake side configured as described above, when no exciting current is applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, the armature shaft 310 is moved by the upper spring 314. The downward urging force (that is, the direction in which the auxiliary intake valve 70b is opened) and the upward movement of the auxiliary intake valve 70b by the lower spring 316 (that is, the direction in which the auxiliary intake valve 70b is closed).
To the armature shaft 3
10 and the auxiliary intake valve 70b are held in a state in which they are in contact with each other and elastically supported at a predetermined position, that is, a so-called neutral state.

In the above-described intake-side electromagnetic drive mechanism, when an exciting current is applied to the first electromagnetic coil 308, the armature 311 is placed between the first core 301, the first electromagnetic coil 308, and the armature 311. An electromagnetic force in the direction of displacing toward the first core 301 is generated, and the second electromagnetic coil 30
When an exciting current is applied to the coil 9, an electromagnetic force is generated between the second core 302, the second electromagnetic coil 309, and the armature 311 in a direction for displacing the armature 311 toward the second core 302.

Therefore, in the intake-side electromagnetic drive mechanism, the first
The excitation current is alternately applied to the electromagnetic coil 308 and the second electromagnetic coil 309 of the
Moves forward and backward, whereby the valve body 700 is driven to open and close. At this time, the opening / closing timing of the sub intake valve 70b can be controlled by changing the timing of applying the exciting current to the first electromagnetic coil 308 and the second electromagnetic coil 309 and changing the magnitude of the exciting current.

In order to change the cam lift and opening / closing timing of the sub intake valve 70b instead of the above-mentioned electromagnetic drive mechanism, the following variable valve mechanism can be provided.
That is, for example, in order to change the cam lift amount and opening / closing timing of the auxiliary intake valve 70b, a portion driven by the timing belt and a portion fixed to the camshaft 12 are divided, and the inner and outer helical splines provided therebetween are provided. A hydraulic chamber is provided between the cam and the intake / exhaust valve by making the phases of the two different by axially moving
Various known variable valve operating systems, such as one that adjusts the oil amount in the hydraulic chamber with a solenoid valve or the like, can be employed.

Next, as shown in FIGS. 1 and 2, the first intake pipe 16 is connected to a surge tank 17, to which an upstream intake pipe 18 is connected. , Is connected to an air cleaner box 19 for removing dust and dirt from the intake air.

A vacuum sensor 20 for outputting an electric signal corresponding to the pressure in the surge tank 17 is attached to the surge tank 17. In addition, the upstream side intake pipe 1
The throttle valve 8 is provided with a throttle valve 21 for adjusting the air flow rate in the upstream intake pipe 18. The throttle valve 21 includes a throttle actuator 22 composed of a stepping motor or the like, which opens and closes the throttle valve 21 in accordance with the magnitude of the applied power, and a throttle which outputs an electric signal corresponding to the opening of the throttle valve 21. A position sensor 23 and an accelerator position sensor 25 which is mechanically connected to the accelerator pedal 24 and outputs an electric signal corresponding to the operation amount of the accelerator pedal 24 are attached. The mass of the fresh air flowing through the upstream intake pipe 18 upstream of the throttle valve 21 (the amount of intake air)
Is provided with an air flow meter 26 that outputs an electric signal corresponding to.

On the other hand, each exhaust port 18 of the internal combustion engine 1
Each exhaust branch pipe 8 attached to the cylinder head 1a
a. The exhaust branch pipe 8a is connected to the exhaust pipe 8 via an exhaust purification catalyst (not shown).

This internal combustion engine 1 has a crankshaft 23
The crank position sensor 13 includes a timing rotor 13a attached to an end of the cylinder block 1b and an electromagnetic pickup 13b attached to a cylinder block 1b near the timing rotor 13a.

The internal combustion engine 1 is provided with a water temperature sensor 14 for detecting the temperature of the cooling water flowing through the cooling water passage 1c formed therein. The ECU 40 includes a throttle position sensor 23, an accelerator position sensor 25,
Air flow meter 26, crank position sensor 1
3. Various sensors such as a water temperature sensor 52 are connected via electric wiring, and output signals of the sensors are input to the ECU 40.

The ECU 40 includes a vacuum sensor 2
0, various sensors such as a throttle position sensor 23, an accelerator position sensor 25, an air flow meter 26, a crank position sensor 13, and a water temperature sensor 14 are connected via electric wiring.

The ECU 40 determines the operating state of the internal combustion engine 1 using the output signals from the various sensors as parameters, and controls the igniter 6a, the fuel injection valve 9, and the like according to the determination result.

Here, as shown in FIG. 4, the ECU 40 controls the CPs connected to each other by a bidirectional bus 400.
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 input port 405 receives an output signal of a sensor that outputs a digital signal, such as the crank position sensor 13, and outputs those output signals to C.
The data is transmitted to the PU 401 or the RAM 403.

The input port 405 is connected to an A / D 407 for an output signal of a sensor that outputs a signal in the form of an analog signal, such as the throttle position sensor 23, the accelerator position sensor 25, the air flow meter 26, the vacuum sensor 20, and the water temperature sensor 14. And outputs those output signals to the CPU 401 and the RAM 403.

The output port 406 is connected to the CPU 40
1 is transmitted to the igniter 6a, the fuel injection valve 9, and the like. 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, a sub intake valve opening / closing timing control routine for determining the opening / closing timing of the sub intake valve 70b, Application programs such as an ignition timing control routine for determining the ignition timing of the ignition plug 6 of each cylinder 2 and a throttle opening control routine for determining the opening of the throttle valve 21 are stored.

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, A main intake valve / exhaust 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 main intake valve 70a and the exhaust valve 80; A sub-intake opening / closing timing control map showing the relationship, an ignition timing control map showing the relationship between the operating state of the internal combustion engine 1 and the ignition timing of each ignition plug 6, a relationship between the operating state of the internal combustion engine 1 and the opening of the throttle valve 21 And the like.

The RAM 403 stores an output signal of each sensor, a 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 13. The RAM
Various data stored in 403 is rewritten to the latest data every time the crank position sensor 13 outputs a signal.

The backup RAM 45 is a non-volatile memory that retains data even after the operation of the internal combustion engine 1 is stopped, and stores learning values for various controls. The CPU
401 operates based on the application program stored in the ROM 402, and executes fuel injection control, exhaust valve opening / closing control, ignition control, and the like in addition to auxiliary intake valve opening / closing control.

Hereinafter, the control of the opening / closing timing of the auxiliary intake valve according to the present embodiment will be described with reference to FIG. In FIG. 6, reference numeral 34 denotes the open / close state of the sub intake valve 70b. Similarly, 32 indicates the open / closed state of the exhaust valve 80, and 33 indicates the open / closed state of the main intake valve 70a. In FIG. 6, the exhaust valve 80
Begins to open when the piston 3 is just before bottom dead center (BDC) and closes after passing top dead center (TDC). On the other hand, the main intake valve 70a starts to open when the piston 3 reaches the top dead center (TDC) and closes when the piston 3 passes the bottom dead center (BDC).

As shown, the auxiliary intake valve 70b is controlled as follows at the time of a cold start and at the time of a high load. First, the piston 3 is opened in the latter half of the exhaust stroke before reaching the top dead center (TDC) and the exhaust valve 80 is closed, and the next main intake valve 7 is opened.
0a is closed in the first half of the intake stroke when it is opened. Next, the piston 3 reaches the bottom dead center (BDC) and is opened in the latter half of the intake stroke before the main intake valve 70a is closed, and is closed after the main intake valve 70a is closed. At this time, the supercharger 10 operates in synchronization with the opening and closing of the sub intake valve 70b. The ECU 40 sends a signal to the supercharger drive mechanism 31 to open the sub intake valve 70b to operate the supercharger 10.

As described above, at the time of a cold start (for example, when the water temperature is 40 ° C. or lower), the auxiliary intake valve 70b opens in the latter half of the exhaust stroke and the latter half of the intake stroke. E from the signal from the water temperature sensor 14
The CU 40 makes a determination and gives an instruction to open the sub intake valve 70b to the drive mechanism 31 of the sub intake valve 70b.

When the auxiliary intake valve 70b is opened in the latter half of the intake stroke, the supercharged air flows into the cylinder 2 and the intake air is disturbed, so that the combustion is improved. Also, the auxiliary intake valve 70
The exhaust gas becomes lean due to the opening of the valve in the latter half of the exhaust stroke of b, and the unburned HC burns to raise the exhaust gas temperature. Therefore, the warming property is enhanced, and the catalyst can reach the activation temperature quickly.

Next, the valve opening control of the sub intake valve 70b under a high load will be described. First, when the load is low, the auxiliary intake valve 7
0b is stopped. That is, there is little need to improve the engine output by forcibly scavenging the exhaust gas by the auxiliary intake valve 70b and improving the volumetric efficiency by inhaling fresh air. Further, in order to suppress the generation of NOx due to the air-fuel ratio becoming lean due to the intake air in the latter half of the exhaust stroke, the main intake valve 70a and the exhaust valve 80 are maintained in a normal operation state, and the auxiliary intake valve 70b
Is desirably stopped.

On the other hand, when the engine is supplied with a large amount of fuel at low speed and high load and at high speed and high load, the sub intake valve 70b is opened in the latter half of the exhaust stroke (partial first half of the intake stroke) as shown in FIG. Accordingly, when the supercharged air is sent into the cylinder 2, the exhaust gas becomes lean, unburned HC is burned, and the purification performance of the catalyst is improved by increasing the exhaust gas temperature.
Further, knocking is suppressed by forced scavenging of the combustion gas. In this case, since a large amount of unburned HC is present in the exhaust gas, that is, the air-fuel ratio is rich, the generation amount of NOx is small even if the supercharged air is sent in the latter half of the exhaust stroke.

Further, as shown in FIG. 6, when the supercharged air is sent into the cylinder 2 by opening the sub intake valve 70b in the latter half of the intake stroke (the first half of the partial compression stroke), the fresh air sucked in And the output of the internal combustion engine 1 is improved. At this time, in order to inhale more fresh air, it is not necessary to open the intake valve when the exhaust valve is still open (the latter half of the exhaust stroke), that is, to overlap the so-called intake / exhaust valve opening timing. Therefore, the main exhaust valve 70 is
The valve opening timing of a can be delayed.

As described above, in the internal combustion engine of the present invention, by delaying the valve opening timing of the main exhaust valve 70a, it is possible to prevent the fuel from flowing into the exhaust system and to prevent the residual gas from returning to the intake system. This is especially effective at high speed and high load.

The ECU 40 determines whether or not the engine is under a heavy load by a signal from the accelerator position sensor 25.
Is determined, and if the accelerator opening is equal to or more than a predetermined value, it is determined that the load is high and the auxiliary intake valve 70b is opened. When the ECU 40 determines that the load is high, the ECU 40 sends a signal to the drive mechanism 31 of the sub intake valve 70b to operate it.

In the case where the auxiliary intake valve 70b is controlled to be opened in the latter half of the exhaust stroke and the latter half of the intake stroke, the valve opening timing in the latter half of the exhaust stroke and the latter half of the intake stroke are independently controlled as necessary. Can also be controlled. For example, if the secondary intake valve 70b is always opened in the latter half of the intake stroke, there is an effect of improving the combustion by generating turbulence in the intake air.

Hereinafter, the control of the internal combustion engine 1 will be described with reference to the flowcharts of FIGS. FIG. 7 is a flowchart of the opening / closing control of the sub intake valve 70b according to the present embodiment, and is a control routine for opening the sub intake valve 70b at the time of a cold start of the internal combustion engine 1.

This routine is executed by the ECU 20 by interruption every predetermined time. Referring to FIG.
First, at step 100, it is determined whether the water temperature is 40 ° C. or less. The opening of the sub intake valve is, for example, at the time of startup and when the water temperature is 40 ° C. or lower. Step 100
If it is determined that the condition for opening the sub intake valve is not satisfied, the control is terminated.

On the other hand, if it is determined in step 100 that the condition for opening the sub intake valve is satisfied, the routine proceeds to step 101, where the sub intake valve is opened in the latter half of the exhaust stroke and the latter half of the intake stroke. The opening of the auxiliary intake valve in the latter half of the intake stroke causes intake turbulence and improves combustion.

Further, by opening the auxiliary intake valve in the latter half of the exhaust stroke, the exhaust gas becomes lean, the combustion of unburned HC is promoted, and the warm-up property of the catalyst is improved. Then, Step 1
At 02, it is determined whether the water temperature has reached 40 ° C. or higher.
If it is determined that the water temperature has reached 40 ° C. or higher, this control ends.

On the other hand, if it is determined in step 102 that the water temperature is less than or equal to 40 ° C., the flow returns to step 101, and the operation of opening the auxiliary intake valve in the latter half of the exhaust stroke and the latter half of the intake stroke is continued. Next, if it is determined in step 102 that the water temperature has reached 40 ° C. or higher, this control is terminated.

FIG. 8 is a flowchart of valve opening control of the sub intake valve 70b performed when the internal combustion engine is under a high load. This routine is executed by the ECU 40 by interruption every predetermined time.

Referring to FIG. 8, first, at step 200, it is determined whether or not the engine is under a high load state based on the accelerator opening measured by the accelerator position sensor 25. If it is determined that the load is not high, the routine exits.

On the other hand, when it is determined that the load is high, the routine proceeds to step 201, where the auxiliary intake valve 70b is opened in the latter half of the exhaust stroke and the latter half of the intake stroke. The opening of the auxiliary intake valve in the latter half of the intake stroke causes intake turbulence, thereby improving combustion and improving engine output.

Further, by opening the auxiliary intake valve in the latter half of the exhaust stroke, the exhaust gas becomes lean, thereby promoting the combustion of unburned HC, and improving the purification performance of the catalyst and preventing knocking.

Next, at step 202, it is determined whether or not the high load state continues. If it is determined that the load is not high, this control ends. On the other hand, if it is determined in step 102 that the vehicle is in a high load state,
The operation of opening the auxiliary intake valve in the latter half of the exhaust stroke and the latter half of the intake stroke is continued. Next, in step 202, it is determined again whether or not the load is high, and if it is determined that the load is not high, the control is terminated.

[0079]

As described above, according to the present invention, the intake system is divided and the pressure and intake timing of the sub intake system can be made different from those of the main intake system. Increased efficiency is achieved.

Further, since the auxiliary intake valve has a stop mechanism, the amount of unnecessary NOx can be reduced by opening the auxiliary intake valve only when necessary, such as when the temperature is low or when the load is high.

[Brief description of the drawings]

FIG. 1 is an overall side view showing a schematic configuration of an internal combustion engine of the present invention.

FIG. 2 is an overall plan view showing a schematic configuration of an internal combustion engine of the present invention.

FIG. 3 is a sectional view showing a structure of an electromagnetic drive mechanism of a sub intake valve.

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

FIG. 5 is an overall plan view showing a schematic configuration of an internal combustion engine according to another embodiment of the present invention.

FIG. 6 is a diagram showing opening / closing timings of an intake valve, a sub intake valve, and an exhaust valve.

FIG. 7 is a flowchart of valve opening control of a sub intake valve at the time of cold.

FIG. 8 is a flowchart of valve opening control of a sub intake valve under a high load.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Piston 4 ... Crankshaft 6 ... Spark plug 7a, 7b ... Intake port 8a ... Exhaust port 9 ... Fuel injection valve 13 ... Crank position sensor 40 ... ECU 70a ... Main intake valve 70b ... Sub intake valve 80 ... Exhaust valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02B 37/00 302 F02B 37/00 302A F-term (Reference) 3G005 GB17 GD07 GD14 HA08 HA09 JA53 3G018 AA05 AB07 AB08 AB09 AB11 CA16 DA34 DA36 DA38 DA41 DA48 DA51 EA02 EA11 EA16 EA17 FA01 FA02 FA07 FA08 FA12 FA22 GA06 GA08 3G092 AA01 AA05 AA11 AA13 AA18 AB02 CB02 DA01 DA05 DA07 DA09 DA11 DA14 DB02 DB03 DC03 DG02 FG05 FA17 GA02 FA05 GA17 FA26 HA05Z HA06Z HA13X HE03Z HE08Z HF08Z

Claims (3)

[Claims] A plurality of intake ports are provided, at least one of which is a main intake system intake port that is opened and closed by a main intake valve, and a fuel supply device is installed in the main intake system intake port. At least one other is an intake port of a secondary intake system that is opened and closed by a secondary intake valve, and the intake port of the secondary intake system is connected to a pressurized air supply passage including a supercharger,
An internal combustion engine having a split intake system, wherein the auxiliary intake valve is opened in the latter half of the exhaust stroke and / or the latter half of the intake stroke, and can be stopped by a stop mechanism. 2. The internal combustion engine having a split intake system according to claim 1, wherein the main intake valve and the exhaust valve have valve opening timings set so that the valve opening states do not overlap each other. 3. An internal combustion engine having a split intake system according to claim 1, further comprising a variable valve mechanism for adjusting the opening / closing timing of said auxiliary intake valve.