JP2001304013A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of obtaining desired air/fuel ratio by preventing A/F disorder. SOLUTION: An intake port 26 is provided in a cylinder 21, a plurality of openings of the intake port 26, with its downstream branching to appear in a combustion chamber, are formed per one cylinder, a total opening area is spread, also an intake valve 28 is provided in the above each opening, an injector 32 is arranged in the upstream of the intake port 26, partly of and the rest of the intake valve 28 are stopped or opened/closed alternately in a closed condition in each specific period at light load operation time, the above rest of the intake valve is operated and closed according to ending of an intake stroke when the above partly of the intake valve is placed in the above stopped condition, the above partly of the intake valve is operated and closed according to ending of the intake stroke when the above rest of the intake valve is placed in the above stopped condition, after the intake valve, operated at present but expected to stop at intake stroke time in the.next time, is closed according to ending of the intake stroke in this time, fuel injection by the injector 32 is performed.

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 employing a multi-valve in which the total area of an intake port formed in a cylinder head on the combustion chamber side is increased by increasing the number of valves.

[0002]

2. Description of the Related Art If one intake / exhaust valve is provided for each cylinder, four operations of intake, compression, expansion, and exhaust of the engine can be performed for the time being.

However, this is not enough for high-performance engines, and it is necessary to instantaneously introduce and discharge more mixed gas into the combustion chamber. For this reason, a multi-valve has been proposed in which the number of valves is increased to increase the total area of the opening on the combustion chamber side of the intake port provided in the cylinder head. One multi-valve has two intake valves and two exhaust valves. Engines with a total of four valves per cylinder are prevalent.

[0004] In a high-performance engine employing a multi-valve, the valve timing is also controlled by a computer, and in recent years, its operation has been performed by employing an electromagnetically driven valve operating mechanism (hereinafter referred to as "electromagnetically driven valve" unless otherwise specified). It has been precisely controlled.

The electromagnetically driven valve controls the opening and closing of the valve by using an electromagnetic force. The electromagnetically driven valve is formed of a magnetic material and has an armature as a movable piece that moves forward and backward in conjunction with the valve. A valve-closing electromagnet that attracts the armature to close the valve, a valve-opening electromagnet that also attracts the armature to open the valve, a valve-closing-side return spring that biases the armature in the valve-closing direction, and a valve-opening direction And a valve-opening-side return spring that urges the valve. Then, by combining this valve operating mechanism with the valve, the valve is freely operated and controlled.

In an electromagnetically driven valve, both magnets are arranged in series with an appropriate space between the valve-closing electromagnet and the valve-opening electromagnet, and an armature is arranged in the space. When the exciting current is not applied to the electromagnetically driven valve, the armature is held at an intermediate position of the space in a neutral state in which the spring force of the valve-side return spring and the spring force of the valve-side return spring are balanced.

When an exciting current is applied to the electromagnetically driven valve, an electromagnetic force is generated between the valve closing electromagnet and the valve opening electromagnet to displace the armature toward the valve closing electromagnet or the valve opening electromagnet. The armature advances and retreats toward the valve-closing electromagnet side or the valve-opening electromagnet side by the electromagnetic force and the urging force of the spring, thereby opening and closing the valve linked to the armature.

When an electromagnetically driven valve is used, the valve can be operated independently at any time by correcting the timing of applying an exciting current to the valve-opening electromagnet and the valve-closing electromagnet regardless of the rotation of the crankshaft. .

On the other hand, in the case of light load operation such as running at low speed, the engine operates even if the amount of intake air is small.
Opening and closing all of the multi-valves is a waste of energy. Therefore, in the case of the four valves, it is considered sufficient to operate only one of the two intake valves. In addition, the smaller the number of operating valves, the lower the power consumed by the electromagnetically driven valve.

As a technique for alternately operating two intake valves and stopping one valve while the other is operating, a technique disclosed in Japanese Patent Application Laid-Open No. 9-287423 is exemplified.

[0011]

By the way, in an engine employing a multi-valve, an injector is provided upstream of an intake port and fuel is injected from the injector. Although there is an engine having a structure in which the downstream side of the intake port is branched so as to be introduced even if it is directed, when the operation of the intake valve is performed instead of the operation as described above, the fuel injected from the injector operates. Not only the middle valve but also the stopped valve. Since the stopped valve is in the closed state, it is conceivable that the injected fuel may be accumulated as droplets on the back of the stopped valve (valve face).

Therefore, when the stopped valve is opened next time to be operated, the accumulated fuel is dripped into the combustion chamber, and as a result, a desired air-fuel ratio cannot be obtained. There is a risk of that.

The present invention has been made in view of the above circumstances, and has as its technical object to provide an internal combustion engine capable of preventing A / F roughness due to liquid dripping and obtaining a desired air-fuel ratio.

[0014]

The present invention employs the following means in order to solve the above-mentioned problems. That is, in the internal combustion engine according to the present invention, the downstream side of the intake port provided in the cylinder is branched to form a plurality of openings of the intake port facing the combustion chamber per cylinder to increase the total opening area and increase the total opening area. An intake valve is provided at each opening, and a fuel injection device is arranged upstream of the intake port. During a specific engine operation, some of the intake valves and the remaining intake valves are alternately arranged at specific intervals. When the part of the intake valves is in the stopped state, the remaining intake valves are actuated and closed at the end of the intake stroke, and the remaining intake valves are closed and stopped. Is in the stop state, some of the intake valves are operated to close at the end of the intake stroke, and the intake valves that are currently operating but are scheduled to be stopped at the next intake stroke are changed to the current state. After the valve is closed at the end of the intake stroke Performing injection control with serial fuel injection device.

In the fuel injection device, fuel injection timing is controlled by fuel injection control means. The fuel injection control means may operate the fuel injection device during an engine operation stroke during a compression stroke. preferable.

Further, it is preferable that the injection is performed at an early stage of the compression stroke. In addition, it is preferable that an electromagnetically driven valve train is applied to the valve train of the intake valve.

Here, an ECU that controls the entire internal combustion engine and controls the operation of the valve operating mechanism of the intake valve and the exhaust valve will be briefly described, and the components of the present invention will also be described.

The ECU comprises a central processing unit CPU and a read-only memory RO connected to each other by a bidirectional bus.
M, a random access memory RAM, a backup RAM, an input interface circuit, an output interface circuit, and the like.

The input interface circuit is electrically connected to various sensors mounted on the internal combustion engine or the vehicle. When output signals of these various sensors enter the ECU from the input interface circuit, these parameters are temporarily randomized. It is stored in the access memory RAM.

Then, based on the parameters, the CPU
Performs the necessary arithmetic processing. In executing the arithmetic processing, the CPU calls the parameters stored in the random access memory RAM via the bidirectional bus when necessary.

The output interface circuit is electrically connected to an electromagnetically driven valve train. Then, the valve operating mechanism of the intake valve is operated based on the calculation result of the CPU performed based on the output signals of the various sensors, and as a result, the opening / closing control of the valve is performed.

The "number of openings" means, for example, two or more openings. Therefore, there are two or more intake valves. An injector is suitable for the “fuel injection device”.

"Specific engine operation" means, for example, such as when the vehicle is running at a low speed or running downhill, which is sufficient to operate the internal combustion engine even if the amount of intake air is small. Light load operation.

The "partial intake valve" means, for example, in the case of an internal combustion engine having two intake valves, one of the intake valves, and in the case of three intake valves, One or two of them. Therefore, the “remaining intake valve” refers to the other intake valve in the case of the two valves, and refers to the remaining two or one valve in the case of the three valves.

"Alternately operating or stopping in the closed state" means that if one of the two intake valves is used, one of the intake valves is operated and the other is closed and stopped.
Stopping one of the valves in the closed state means activating the other intake valve.

In the case where the three intake valves are used,
If one valve is operated, the remaining two valves are stopped in a closed state, and if two valves are stopped in a closed state, the remaining one valve is operated.

The “specific period” can be exemplified by one cycle in which the piston reciprocates in the cylinder and performs a series of four operations of suction, compression, explosion, and exhaust. However, as long as the fuel is formed as droplets by the fuel injection and accumulates in the intake port, the number of cycles is not limited to one but may be two or more as long as the fuel does not drip.

The greater the number of cycles until some or all of the remaining intake valves stop or operate, the greater the amount of injected fuel adhering to the intake ports, but the number of times the expansion stroke that generates high heat elapses If it increases, the fuel attached to the intake port can be vaporized accordingly.

The "fuel injection control means" is a fuel injection control execution program among the various application programs stored in the ROM for implementing various routines for executing control of the internal combustion engine. Also, since the ROM attribute for storing this program is in the ECU,
Is referred to as fuel injection control means.

The initial period of the compression stroke depends on the type of the internal combustion engine and the vehicle equipped with the internal combustion engine, and is determined by experiments and calculations. desirable.

In the internal combustion engine of the present invention, when a specific engine is operated,
Some of the plurality of intake valves and the remaining intake valves are alternately stopped or opened / closed in a closed state every specific period. Therefore, when some of the intake valves are in the stopped state, the remaining intake valves are in the operating state, and the operated intake valves are closed with the end of the engine intake stroke. Conversely, when the remaining intake valves are in a stopped state, some of the intake valves are in an operating state, and some of the operating intake valves are closed at the end of the intake stroke. Then, the injection control by the fuel injection device is performed after the intake valve which is scheduled to be stopped during the next intake stroke but is currently operating is closed with the end of the current intake stroke.

Therefore, the operation of some of the intake valves that are currently in operation is stopped at least once before the next operation, and the remaining intake valves are also operated next time if they are currently in operation. Stop at least once before doing so.

Conversely, some of the intake valves that are currently stopped are operated at least once before the next stop, and the remaining intake valves are also stopped if they are currently stopped until the next stop. At least once.

As described above, the engine operation in which a part of the intake valves is operated and the remaining intake valves are stopped during a specific engine operation is referred to as a one-valve operation in this specification. Therefore, in the case of the one-valve operation, at least two expansion strokes elapse before the currently stopped or operating intake valve is stopped or operated next time, respectively.

More specifically, it is assumed that a cycle in which some of the intake valves and the remaining intake valves are alternately stopped or operated in the closed state is performed, for example, every one cycle of the engine operation stroke.

When the intake-compression-expansion-exhaust operation stroke is performed by the intake valve and the exhaust valve that are currently in operation, the intake valve that is currently stopped is the next to operate, and this time is the next time. An intake-compression-expansion-exhaust operation stroke is performed by the intake valve and the exhaust valve. After that, the intake valve which has been stopped is the next turn to operate, and the intake-compression-expansion-exhaust operation process is performed by the intake valve and the exhaust valve. Is repeated during a specific engine operation, and fuel is injected during the compression stroke, so that the expansion valve passes twice before the currently stopped intake valve stops next time.

In the single-valve operation, the stopped intake valve is in the closed state, and the injected fuel is accumulated as droplets on the back of the valve as described above. However, the other intake valves are operating during the period in which the stopped intake valve is stopped, and the internal combustion engine itself uses the other intake valve and the exhaust valve to operate the intake-compression-expansion-exhaust stroke. Via. Therefore,
At this time, the liquid droplets accumulated in the stopped intake valve receive heat during the expansion stroke and evaporate in the intake port. However, not all droplets accumulated in the intake valve at this time are necessarily vaporized, and it is conceivable that droplets adhere to the intake port.

Next, when it is the turn to operate the intake valve that has been stopped, the operation of the intake valve and the exhaust valve passes through the operation process of intake-compression-expansion-exhaust. At this time, the fuel in the droplet state, which has not been vaporized during the previous stop and still adheres and remains on the intake valve which has been turned, is subjected to the second expansion by the execution of the operation of the intake valve itself. After going through the process, it receives the heat at that time and evaporates again.
As a result, the fuel adhering to the stopped intake valve experiences the expansion stroke twice before the next stop of the intake valve in the stopped state. Fuel adhering to the valve easily evaporates, effectively preventing dripping.

Further, since it is effective in preventing liquid dripping, atomization of fuel is promoted, and A / F is not generated without A / F roughness.
/ F is stabilized. Furthermore, it is effective to make the dropletized fuel into an atomized state by passing the expansion stroke having the largest calorific value twice, but by executing it during the compression stroke, fuel injection Since the fuel injected from the device is exposed to a high temperature state, it is easy to vaporize. Therefore, as described above, when the fuel is injected at an early stage rather than at the end of the compression stroke, the fuel can be exposed to the high temperature state for a longer period, so that the fuel adhering to the stopped valve can be more effectively vaporized. it can.

In addition, according to the present invention, since it becomes difficult for the fuel to adhere to the wall surface of the intake port, when the engine is operating at a constant rotation speed, the fuel is rapidly accelerated and the fuel injection amount is increased thereafter. Even in this case, the increased amount is placed in a state where it is easily vaporized, so that it can be said that it is effective in preventing dripping regardless of the number of rotations.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the internal combustion engine according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to the present invention. The internal combustion engine 1 shown in FIG. 1 has a plurality of (four in this embodiment) cylinders: a first cylinder 21.
-1, second cylinder 21-2, third cylinder 21-
And a fourth cylinder 21-4, and an injector 32 which is a fuel injection device for directly injecting fuel into each of these cylinders.
-In-line 4-cylinder 4-cycle gasoline engine performed in cylinder order of -4-2.

Although only the first cylinder 21-1 is shown in the drawing, the first cylinder 21-1, the second cylinder 21-2, and the second cylinder 21-2 extend from the near side to the far side in FIG.
Third cylinder 21-3 and fourth cylinder 21-4
Is arranged.

The internal combustion engine 1 has four cylinders 21-
Cylinder block having a water jacket 2 serving as an engine cooling water passage, and cylinder cylinders 1, 21-2, 21-3, and 21-4 (these cylinders may be collectively referred to simply by reference numeral 21). 1b and a cylinder head 1 fixed to the upper part of the cylinder block 1b.
a and an oil pan 1c fixed to a lower portion of the cylinder block 1b.

A crank shaft 23 as an engine output shaft is rotatably supported on the cylinder block 1b.
The crank shaft 23 is connected via a connecting rod 3 to a piston 22 slidably mounted in each cylinder 21.

Above the piston 22, when the piston 22 is at the top dead center, the upper part of the cylinder 21 and the piston
A combustion chamber is formed by the recess 22b provided in the head 22a and the piston head 22a (in the drawing, a space portion which is not yet a combustion chamber is indicated by reference numeral 24 because the piston 22 is located before the top dead center. .). The combustion chamber compresses and ignites a mixture obtained by mixing intake air and engine fuel.

An ignition plug 25 is attached to the cylinder head 1a so as to face the combustion chamber. An igniter 25a for applying a drive current to the ignition plug 25 is connected to the ignition plug 25.

The cylinder head 1a employs a multi-valve to increase the total area of the intake port and the exhaust port on the upstream side facing the combustion chamber. More specifically, the cylinder head 1a is branched on the downstream side into a plurality (two in this embodiment) of open ends (only one is shown in the drawing).
And an exhaust port 27 having a plurality of (two in this embodiment) open ends (only one is shown in the drawings) facing the combustion chamber. Each opening end of the intake port 26 is opened and closed by an intake valve 28 which is an intake valve supported on the cylinder head 1a so as to be able to move forward and backward.

An injector 32 is mounted on the upstream side of the intake port 26, and fuel is dispersed and injected from the injector 32 toward each of the opening ends formed by branching the downstream side of the intake port 26. Each of the open ends formed by branching the upstream side of the exhaust port 27 is opened and closed by an exhaust valve 29 which is an exhaust valve supported on the cylinder head 1a so as to be able to move forward and backward.

The intake valves 28, 28 and the exhaust valves 29, 29 are opened and closed by an electromagnetic drive mechanism which opens and closes these valves by using an electromagnetic force.

The electromagnetic drive mechanism for operating the intake valves 28, 28 is indicated by the reference numeral 30 and hereinafter referred to as "the intake-side electromagnetic drive mechanism 30". Also, the exhaust valve 29,
Reference numeral 31 denotes an electromagnetic drive mechanism that operates 29, and hereinafter,
This will be referred to as “exhaust-side electromagnetic drive mechanism 31”.

By utilizing the electromagnetic force generated by the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31, respectively, the valve mechanism for opening and closing the intake valves 28, 28 and the exhaust valves 29, 29 is electromagnetically driven. The valve mechanism is referred to as 30A and 31A, respectively.
Indicated by The intake-side electromagnetically driven valve train 30A and the exhaust-side electromagnetically driven valve train 31A are mounted for each cylinder.

Here, the intake side electromagnetically driven valve mechanism 30A
(Hereinafter referred to as “intake side electromagnetically driven valve 30A”) and exhaust side electromagnetically driven valve mechanism 31A (hereinafter referred to as “exhaust side electromagnetically driven valve 3A”).
1A ". ) Will be described in detail.
The two mechanisms 30A and 31A have the same configuration. For this reason,
FIGS. 1 and 2 show one intake side electromagnetically driven valve 30A.
, And for the description of the other exhaust-side electromagnetically driven valve train 31A, refer to the configuration of the intake-side electromagnetically driven valve train 30A.

In the intake-side electromagnetically driven valve 30A, the constituent members of the intake valve 28 are given alphabetical characters 28, such as 28a, so that the exhaust valve 29 of the exhaust-side electromagnetically driven valve 31A is related. It has been shown that the components are valve components that are substantially the same but have different uses.

As can be seen from FIGS. 1 and 2, the cylinder head 1a of the internal combustion engine 1 has a cylinder block 1
The lower head 10 includes a lower head 10 directly fixed to the upper surface of the lower head 10b, and an upper head 11 provided above the lower head 10.

In the lower head 10, intake ports 26, 26 corresponding to the respective cylinders 21 are formed. At the open ends of the respective intake ports 26 on the combustion chamber side, intake valves 2 are provided.
The valve seat 12 is provided as a valve seat on which the eighth valve head 28a is seated.

The back of the umbrella (valve face), which is the portion of the valve head 28a that is in close contact with the valve seat 12, is designated by the reference numeral 28e. The lower head 10 has a through hole having a circular cross section from the inner wall surface of each intake port 26 to the upper surface of the lower head 10. A cylindrical valve guide 13 for guiding the valve shaft 28b of the intake valve 28 so as to be able to move forward and backward is inserted into the through hole.

The upper head 11 has a core mounting hole 14 having a circular cross section. The core mounting hole 14 is located on the same axis P with the valve guide 13. The core mounting hole 14 includes a small-diameter portion 14a located at an upper portion and a large-diameter portion 14b located at a lower portion.

The small-diameter portion 14a has an annular upper core 301 and a lower core 302 made of a soft magnetic material inserted into openings at both ends of the small-diameter portion 14a. Both cores 301 and 302 are arranged in series in the axial direction with a predetermined space 303 therebetween. In addition, upper
At the upper end of the core 301 and the lower end of the lower core 302,
A flange 301a and a flange 302a are formed respectively.

The upper core 301 is, as shown in FIG.
The lower core 302 is inserted into the core mounting hole 14 from below in FIG. 2, and the flange 301a and the flange 302a are brought into contact with the peripheral edge of the core mounting hole 14 so that the upper core 301 and the lower core Small diameter part 1 of 302
Further fitting into 4a is prevented. The space 303 is formed by the fitting. Space part 3
The axial dimension of 03 is determined mainly by the valve lift of the valve head 28a.

Further, a cylindrical upper cap 305 is mounted above the upper core 301. Upper
The cap 305 has a flange portion 305a formed at the lower end thereof, and the flange portion 305a is screwed on the upper surface of the upper head 11 with a bolt 304, so that the upper
The cap 305 is fixed to the upper head 11. At this time, the upper cap 305 including the flange portion 305a
Abuts against the peripheral edge of the upper surface of the flange 301a,
By maintaining this state, the upper core 301 is fixed to the upper head 11.

On the other hand, the lower core 302 is
02a through an annular lower cap 307 and bolt 3
Fixing to the upper head 11 by screwing at 06.
A circular groove is formed in a surface of the upper core 301 located on the space 303 side, and an upper core 301 is formed therein.
The coil 308 is mounted.

On the other hand, on the surface of the lower core 302 located on the space 303 side, a circular groove is formed similarly to the upper core 302, and the lower coil 3 is formed therein.
09 is attached. The upper coil 308 and the lower coil 309 face each other on the same axis P. Then, an electromagnetic force is obtained by supplying an exciting current to these coils 308 and 309. Therefore, the current is called an exciting current. Flowing the exciting current through the coils 308 and 309 is referred to as applying the exciting current to the electromagnetic coil.

In addition, the upper core 301 and the lower core 301
At the center of the core 302, through holes 301b and 302b are formed, respectively. In the middle of the space 303, a disk-shaped armature 311 made of a soft magnetic material is provided.
Is arranged.

The armature 311 has a columnar armature shaft 310 extending vertically from the center thereof. The upper half of the armature shaft 310 reaches the inside of the upper cap 305 through the through hole 301 b of the upper core 301.

The lower half of the armature shaft 310 passes through the through hole 302b of the lower core 302 and reaches the inside of the large-diameter portion 14b. And armature shaft 3
10 so that the armature 311 having the core 10 and the lower core 302 can slide freely with respect to the upper core 301 and the lower core 302, that is, the armature 311 can freely reciprocate up and down in FIG. The diameter of the armature shaft 310 is somewhat smaller than each of the through holes 301b, 302b.

The tip of the armature shaft 310 extending into the upper cap 305 has a disc-shaped upper
The retainer 312 is joined. An upper portion of the upper cap 305 is formed as an opening, and an adjusting bolt 313 is screwed into the opening. An upper spring 314 as urging means is interposed between the upper retainer 312 and the adjustment bolt 313.

The contact surface between the adjusting bolt 313 and the upper spring 314 is provided with a spring having an outer diameter substantially equal to the inner diameter of the upper cap 305.
The seat 315 is interposed.

On the other hand, the tip of the armature shaft 310 extending into the large-diameter portion 14b comes into contact with an end 28d of the intake valve 28 located on the side opposite to the side where the valve head 28a is located, This allows armature
When the shaft 310 and the valve head 28a are in the same straight line P
Located on top.

A disc-shaped lower retainer 28c is joined to the outer periphery of the end portion 28d, and a biasing means is provided between the lower surface of the lower retainer 28c and the upper surface of the lower head 10. The lower spring 316 is interposed.

The intake-side electromagnetic drive mechanism 3 configured as described above
0 is the upper coil 308 and the lower coil 309
When no exciting current is applied to the armature shaft 310, the urging force of the upper spring 314 and the urging force of the lower spring 316 act on the armature shaft 310. Specifically, the armature shaft 310 has a force for urging the armature shaft 310 downward in FIG. 2 (that is, in a direction in which the intake valve 28 is opened) by the upper spring 314, and an upper side in FIG. (I.e., a force that biases the intake valve 28 in the closing direction) acts. As a result, the armature shaft 310 and the intake valve 28 are held in a state in which they contact each other and are elastically supported in the middle of the space, that is, in a so-called neutral state.

If the neutral position of the armature 311 is deviated from the above-mentioned intermediate position due to the initial tolerance or aging of the components, the adjusting bolt 313 is adjusted so that the armature 311 comes to the above-mentioned intermediate position. .

Further, the axial lengths of the armature shaft 310 and the valve shaft 28b are such that when the armature 311 is at an intermediate position of the space 303, the valve head 28a is in the fully open position and the fully closed position. (The position where the valve head 28a is located in FIG. 2).

On the other hand, when an exciting current is applied to the upper coil 308, the electromagnetic force for closing the valve 28 overcoming the biasing force of the upper spring 314 causes the upper core 3
When an excitation current is generated in the lower core 309 and an exciting current is applied to the lower coil 309, an electromagnetic force that opens the valve 28 by overcoming the biasing force of the lower spring 316 is generated in the lower core 302.

In the intake side electromagnetic drive mechanism 30 described above, when an exciting current is applied to the upper coil 308,
Upper coil 308 and armature 311 of core 301
Between them, an electromagnetic force for displacing the armature 311 toward the upper core 301 is generated.

When an exciting current is applied to the lower coil 309, an electromagnetic force for displacing the armature 311 toward the lower core 302 is provided between the lower coil 309 of the lower core 302 and the armature 311. appear.

The upper coil 308 and the lower coil 30
When an exciting current is alternately applied to the armature 9, the armature 311 moves to the side of the applied electromagnetic coil, and the intake valve 28 opens and closes. Therefore, the upper core 301
Is a valve closing electromagnet, and the lower core 302 is a valve opening electromagnet.

At this time, by changing the timing of applying the exciting current to the upper coil 308 and the lower coil 309 and the magnitude of the exciting current, the opening / closing timing of the intake valves 28 can be controlled. .

Further, two intake valves 28 provided for each cylinder can be opened and closed independently by opening and closing control by a drive circuit (not shown). The intake-side electromagnetic drive valve 30A and the exhaust-side electromagnetic drive valve 3
1A is attached to the cylinder head 1a in a state where it is slightly inclined with respect to the cylinder center line L, and a scissor angle φ formed by both electromagnetically driven valves 30A and 31A (see FIG. 1).
However, in other words, the inclination angle formed by each axis line P of the intake-side electromagnetically driven valve 30A and the exhaust-side electromagnetically driven valve 31A with respect to the cylinder center line L is an angle that satisfies the requirements of the intake and exhaust performance. It is attached as follows.

Next, another configuration of FIG. 1 will be described. Each intake port 26 of the internal combustion engine 1 communicates with each branch pipe of an intake manifold (hereinafter, referred to as “in manifold”) 33 which is an intake branch pipe attached to the cylinder head 1a. The in manifold 33 is connected to a surge tank 34 for smoothing the pulsation of the intake air. An intake pipe 35 is connected to the surge tank 34. Intake pipe 35
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 detecting the amount of intake air flowing through the intake pipe 35 as a voltage value and outputting an electric signal corresponding to the voltage value. In a portion of the intake pipe 35 downstream of the air flow meter 44, a throttle valve 39 for controlling an amount of intake air flowing through the intake pipe 35 is provided.

The throttle valve 39 is composed of a stepper motor or the like and has a throttle valve 39 according to the magnitude of the applied current.
Throttle actuator 40, which throttles valve 39 to increase or decrease the opening area of intake pipe 35 in accordance with the opening of throttle valve 39, and detects the opening of throttle valve 39 as a voltage value, and responds to this voltage value. A throttle position sensor 41 that outputs an electric signal obtained by the above-described method and an accelerator position sensor 43 that outputs an electric signal corresponding to the amount of depression of an accelerator pedal 42 are mechanically or electrically combined.

The surge tank 34 has a vacuum sensor 5 for outputting an electric signal corresponding to the internal pressure.
Has zero. On the other hand, each of the exhaust ports 27 is an exhaust manifold (hereinafter, referred to as an "exhaust manifold") 45 which is an exhaust manifold attached to the cylinder head 1a.
The exhaust manifold 45 also communicates with the exhaust pipe 47. The exhaust pipe 47 is provided with a catalytic converter 46 filled with an exhaust gas purifying catalyst.
A muffler (not shown) is provided downstream of the catalytic converter 46.

The exhaust manifold 45 has an air-fuel ratio sensor 48 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst of the catalytic converter 46 (hereinafter referred to as “exhaust air-fuel ratio”).

The exhaust purification catalyst of the catalytic converter 46 is
For example, when the exhaust air-fuel ratio is a predetermined air-fuel ratio close to the stoichiometric air-fuel ratio, hydrocarbons (hereinafter, referred to as “HC”), carbon monoxide (hereinafter, referred to as “CO”), and nitrogen oxides (hereinafter, “NOx”) in the exhaust gas. And the NO contained in the exhaust when the exhaust air-fuel ratio is a lean air-fuel ratio.
When the exhaust air-fuel ratio is a stoichiometric air-fuel ratio or a rich air-fuel ratio, the stored NOx is released, and the released NOx is reduced to purify exhaust gas.
x catalyst and a selective reduction type NOx catalyst that purifies exhaust gas by reducing NOx in exhaust gas when the exhaust air-fuel ratio is lean air-fuel ratio and a predetermined reducing agent is present. They may be formed in combination.

A catalyst temperature sensor 49 for outputting an electric signal corresponding to the floor temperature of the exhaust gas purification catalyst is attached to the catalytic converter 46 containing such an exhaust gas purification catalyst.

The internal combustion engine 1 has a crank position sensor 51 including a timing rotor 51a attached to the end of the crankshaft 23 and an electromagnetic pickup 51b provided near the timing rotor 51a.

Further, the internal combustion engine 1 has a water temperature sensor 52 for detecting the temperature of the cooling water flowing through the water jacket 2.
Is attached to the cylinder block 1b. The operating state of the internal combustion engine 1 having such a configuration is controlled by the ECU 20.

The ECU 20 calculates the throttle position
Various sensors such as a sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, a catalyst temperature sensor 49, a vacuum sensor 50, a crank position sensor 51, and a water temperature sensor 52 are electrically connected. Connected, and the output signal of each sensor is
Is input to

The ECU 20 includes an igniter 25a,
The igniter 25a, the intake-side electromagnetic drive mechanism 30, and the exhaust-side electromagnetic drive mechanism 31 are also electrically connected to the intake-side electromagnetic drive mechanism 30, the exhaust-side electromagnetic drive mechanism 31, the injector 32, and the like based on output signals from the various sensors. , The injector 32 is controlled.

In addition, as shown in FIG. 3, the ECU 20 is connected to a C
PU 401, ROM 402, RAM 403, backup RAM 404, input port 405, output port 406, and A / D connected to input port 405.
A converter (hereinafter referred to as “A / D”) 407;

Sensors that output analog signals such as a throttle position sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, a catalyst temperature sensor 49, a vacuum sensor 50, and a water temperature sensor 52. Are input to the input port 405 via the A / D 407, and the signal input to the input port 405 is transmitted to the CPU 401 and the RAM 403.

The input port 405 receives the output signal of a sensor that outputs a digital signal such as the crank position sensor 51 as it is. In this case, the input signal is input to the input port 405 in the same manner as described above. The signal is transmitted to the CPU 401 and the RAM 403.

The output port 406 transmits the control signal output by the CPU 401 to the igniter 25a, the intake-side electromagnetic drive mechanism 30, the exhaust-side electromagnetic drive mechanism 31, the injector 32, and the throttle actuator 40.

The ROM 402 stores application programs for implementing various routines.
The routine includes, for example, a fuel injection amount (TAU)
Injection control routine for determining fuel injection timing, fuel injection timing control routine for determining fuel injection timing, intake valve opening / closing timing control routine for determining opening / closing timing of intake valves 28, 28, exhaust Exhaust valve opening / closing valve timing control routine for determining the opening / closing valve timing of the valves 29, 29, ignition timing control routine for determining the ignition timing of the ignition plug 25 of each cylinder 21, opening of the throttle valve 39 ( TA), a torque control routine for executing the torque control by changing the timing of applying the exciting current to the intake side electromagnetic drive mechanism 30 and the exhaust side electromagnetic drive mechanism 31, Intake valve 28 or exhaust valve 2
9 controls the attracting current, which is an exciting current necessary to attract one electromagnet from the lower core 302 of the valve-opening electromagnet and the upper core 301 of the valve-closing electromagnet to the other electromagnet. And a suction current control routine for performing a one-valve operation only during a specific engine operation.

"Specific engine operation" means, for example, when the internal combustion engine 1 is running at a low speed enough to operate the internal combustion engine 1 even when the amount of intake air is small, or when the vehicle with the internal combustion engine is running downhill. "Single-valve operation" refers to light load operation such as when
This means engine operation control during an intake stroke in which only some of the intake valves 28 of a plurality of intake valves operate and the remaining intake valves 28 stop.

The ROM 402 stores various control maps in addition to the application programs for executing various routines. For example, a fuel injection amount control map showing the relationship between the engine operating state and the fuel injection amount, a fuel injection timing control map showing the relationship between the engine operating state and the fuel injection timing, the engine operating state and the opening / closing timing of the intake valve 28, Valve opening / closing timing control map showing the relationship between the engine operating state and the opening / closing timing of the exhaust valve 29, the relationship between the engine operating state and the ignition timing of each spark plug 25 , And various control maps such as a throttle opening control map indicating the relationship between the engine operating state and the opening of the throttle valve 39.

The RAM 403 stores output signals of various sensors, calculation results of the CPU 401, and the like. The various data stored in the RAM 403 is rewritten to the latest data every time the crank position sensor 51 outputs a signal.

The backup RAM 405 stores the internal combustion engine 1
Is a non-volatile memory that retains data even after the operation is stopped, and stores learning values and the like related to various controls. CPU 401
Operates according to the various application programs stored in the ROM 402, and controls various operations such as fuel injection, intake valve opening / closing, exhaust valve opening / closing, ignition, exciting current amount, and single valve operation performed only during a specific engine operation. Execute

Next, a description will be given of a fuel injection timing control routine execution program when a single valve operation is performed during a specific engine operation with reference to the flowcharts of FIGS. Although FIGS. 4 and 5 should originally be shown together on the same paper, they are separated by the space of the paper.

The reference numerals (1) and (2) shown in FIG. 4 and the reference numerals (1) and (2) shown in FIG. 5 correspond to the same reference numerals, and guide the destination of the process. For example, (1) in FIG. 4 corresponds to (1) in FIG. 5, and the processing in the route according to (1) in FIG.
Means that the process proceeds to the route according to and the process is continued in FIG.

This program comprises steps 101 to 108 described below.
Is remembered. Then, the program is called by the CPU, and the processes of steps 101 to 108 are executed by C
The PU executes. Note that the symbol S is used, and if it is, for example, step 101, it is omitted as S101.

In S101, it is determined whether or not the state of the internal combustion engine 1 is during a specific engine operation. If an affirmative determination is made in S101, the process proceeds to S102, and if a negative determination is made, this routine ends.

The reason why this routine is terminated when a negative determination is made is that this routine is to perform a one-valve operation during a specific engine operation to determine a suitable fuel injection timing. There is a program for executing the fuel injection timing control routine when the one-valve operation is not performed. However, since this program is not the gist of the present invention, its description is omitted here.

In S102, a one-valve operation is executed. S10
Step 3 is for avoiding the case where the single valve operation is not actually executed during the intake stroke even though the single valve operation execution command is issued in S102. That is, it is determined whether or not some intake valves 28 per cylinder are open during the intake stroke and the remaining intake valves 28 are closed.

If the determination is affirmative in S103, the process proceeds to S104, and if the determination is negative, this routine ends. S
At 104, it is determined whether or not the compression stroke is being performed. The reason for performing the fuel injection during the compression stroke will be described after finishing the description of this flowchart.

If the determination is affirmative in S104, the process proceeds to S105, and if the determination is negative, this routine ends.
This is because injection during the compression stroke is a feature of the present embodiment, and is not applicable when injection is not performed during the compression stroke.

At S105, fuel injection by the injector 32 is performed. The amount of the injection amount depends on the type of the internal combustion engine and the engine operating conditions, and is determined by a fuel injection amount control map or calculation. Since the amount of the injection amount is not the purpose of the present invention, the description thereof is omitted.

At S106, after one cycle, S103
It is determined whether the intake valve 28 (hereinafter, the intake valve 1 unless otherwise specified) is operated and the intake valve 28 (hereinafter, the intake valve 2 unless otherwise specified) is stopped in S103. judge. If a positive determination is made in S106, the process proceeds to S107, and if a negative determination is made, this routine ends. The reason for ending this routine in the case of a negative determination is the same as in S103.

In step S107, it is determined whether or not the compression stroke is being performed. The reason for terminating this routine when a negative determination is made in S108 is the same as the reason described for the negative determination in S104.

In S108, fuel is injected by the injector 32 as in S105. Thus, the internal combustion engine 1
Then, at the time of a specific engine operation, the intake valves 28, 2
8, the intake valves (intake valve 1 or intake valve 2) and the remaining intake valves (intake valve 2 or intake valve 1) are alternately changed every specific period (in the above example, every cycle). It is stopped or opened and closed in the closed state, and when some of the intake valves (the intake valves 1 or 2) are in the stopped state, the remaining intake valves (the intake valves 2 or 1) are activated. When the remaining intake valve (intake valve 2 or intake valve 1) is in a stopped state, the valve is closed at the end of the intake stroke and some of the intake valves (intake valve 1 or intake valve 2) are operated. The intake valve is closed at the end of the intake stroke, and is scheduled to be stopped at the next intake stroke, but the currently operating intake valve is closed at the end of the current intake stroke. I do.

Therefore, as is clear from the description of FIGS. 4 and 5, S103 to S105 and / or S1
06-S108 is referred to as fuel injection control means for operating the injector 32 to control the injection timing and performing fuel injection while the engine operation stroke is in the compression stroke.

The program including S103 to S105 and / or S106 to S108
Since it is stored in the OM and the attribute of the ROM is in the ECU 20, the ECU 20 is referred to as fuel injection control means.

Next, the reason why fuel is injected during the compression stroke will be described with reference to FIG. FIG. 6 shows the operation stroke of the internal combustion engine,
The timing at which the intake valves 1 and 2 stop or operate in the closed state and the injection timing of each intake valve are shown. In addition, the code | symbol T and B in a figure respectively means a top dead center (Top dead center) and a bottom dead center (Botom dead center).

During a specific engine operation, in the internal combustion engine 1, one of the two intake valves 28, 28 (for example, "the intake valve 1") and the other intake valve 28 (for example, the intake valve 28) are used. "Intake valve 2"
That. ) Is alternately stopped or operated in the closed state after a predetermined period. Therefore, when the intake valve 1 is in the stopped state, the intake valve 2 is in the operating state, and the intake valve 2 in the operating state is closed with the end of the intake stroke of the internal combustion engine 1.

On the other hand, when the intake valve 2 is in the stopped state, the intake valve 1 is in the operating state. The intake valve 1 in this operating state is closed with the end of the intake stroke of the internal combustion engine 1. Thus, after the intake valve 28 (for example, the intake valve 2) that is scheduled to be stopped and is currently operating at the next intake stroke closes at the end of the current intake stroke of the internal combustion engine 1, during the compression stroke, The injection control by the injector 32 is performed.

Therefore, one intake valve 2
When the intake valve 8 (for example, the intake valve 2) is currently operating, the operation is stopped once before the intake valve 2 is operated next time.

The same applies to the remaining intake valves 28 (for example, the intake valve 1). If the intake valve 1 is currently in operation, the remaining intake valve 1 must be operated before the next operation of the remaining intake valve 1 next time. The operation is stopped once.

Therefore, in the case of the one-valve operation, two expansion strokes elapse before the stopped or operating intake valve 28 is stopped or operated next time. More specifically, the intake valve 28 currently in operation is
When the intake-compression-expansion-exhaust operation process is performed by the exhaust valve and the exhaust valve, the intake valve 28 that is currently stopped is the next to operate after the execution, and the intake valve 28 and the exhaust An intake-compression-expansion-exhaust actuation stroke by means of a valve is performed. After that, the intake valve 28 which has been stopped is the next to be operated, and the intake-compression-expansion-exhaust operation of the intake valve 28 and the exhaust valve 29 is performed. By repeating such a one-valve operation alternately during a specific engine operation and injecting fuel during the compression stroke,
Two expansion strokes elapse before the currently stopped intake valve 28 stops next time.

In the case of the one-valve operation, the stopped intake valve 28 is in the closed state, so that the injected fuel is accumulated as droplets on the back of the valve as described above. However, during the period in which the stopped intake valve 28 is stopped, the other intake valve 28 is operating, and the internal combustion engine itself uses the other intake valve 28 and the exhaust valve 29 to perform intake-air control. Compression-expansion-
Through the exhaust stroke. Therefore, the droplets accumulated in the stopped intake valve 28 at that time first receive heat during the expansion stroke and evaporate. However, at this time, not all the droplets accumulated in the intake valve 28 are vaporized, and it is conceivable that droplets adhere to the intake port.

Next, the intake, which had been stopped until then,
When it is time to operate the valve 28, the intake valve 28 and the exhaust valve 29 are operated to pass through an intake-compression-expansion-exhaust operation stroke. Therefore,
At that time, the fuel that has adhered to the intake valve 28 and has been in a droplet state still undergoes the second expansion stroke, and at that time also receives heat and evaporates.

As a result, the stopped intake
The fuel accumulated in the valve 28 undergoes two expansion strokes with a large amount of heat before the next stop of the intake valve 28 in the stopped state, so that the fuel adheres to the intake valve 28 in the droplet state. It can be said that this is effective in preventing dripping because the fuel that has been vaporized easily evaporates.

Further, since it is effective in preventing liquid dripping, the atomization of the fuel is promoted, so that a stable A / F can be obtained without A / F being roughened. Further, since the expansion stroke having the largest heat value passes twice, it is effective to make the dropletized fuel into an atomized state by itself, so that the fuel injection may be performed during the compression stroke. In the initial stage of the compression stroke, that is, when fuel is injected just after bottom dead center, the fuel is exposed to high temperature for a longer period of time and becomes easier to vaporize. This is convenient because vaporization can be realized.

In addition, since it becomes difficult for the fuel to adhere to the wall surface of the intake port, even when the engine is operated at a constant rotation speed and then suddenly accelerated to increase the fuel injection amount, the increase is not affected. Since it is easily vaporized, it can be said that it is effective in preventing liquid dripping regardless of the number of rotations.

[0125]

In the internal combustion engine according to the present invention, by performing the single valve operation by controlling the operation of the electromagnetically driven valve operating mechanism, it is possible to prevent A / F deviation due to liquid dripping and obtain a desired air-fuel ratio. it can.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of an electromagnetic drive mechanism.

FIG. 3 is a block diagram showing an internal configuration of an ECU.

FIG. 4 is a flowchart showing a fuel injection timing control routine execution program;

FIG. 5 is a part of a flowchart continuing from FIG. 4;

FIG. 6 is a diagram showing an operation stroke of the internal combustion engine, a time when each intake valve provided per cylinder stops or operates in a closed state, and an injection timing of each intake valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1a Cylinder head 1b Cylinder block 1c Oil pan 2 Water jacket 3 Connecting rod 10 Lower head 11 Upper head 12 Valve seat 13 Valve guide 14 Core mounting hole 14a Small diameter part 14b Large diameter part 20 ECU (Fuel Injection Control Means) 21-1 Cylinder 21-2 Cylinder 21-3 Cylinder 21-4 Cylinder 22 Piston 22a Piston Head 22b Recess 23 Crank Shaft 24 Space 25 Spark Plug 25a Igniter 26 Intake Port 27 Exhaust Port 28 Intake -Valve (intake valve) 28a Valve head 28b Valve shaft 28c Lower retainer 28d Intake valve end 28e Valve face 29 Exhaust valve 30 Intake side electromagnetic drive mechanism 30 A intake side electromagnetically driven valve mechanism (valve mechanism) 31 exhaust side electromagnetically driven mechanism 31A exhaust side electromagnetically driven valve mechanism 32 injector (fuel injection device) 33 in manifold 34 surge tank 35 intake pipe 36 air Cleaner box 39 Throttle valve 40 Throttle actuator 41 Throttle position sensor 42 Accelerator pedal 43 Accelerator position sensor 44 Air flow meter 45 Exhaust manifold 46 Catalytic converter 47 Exhaust pipe 48 Air-fuel ratio sensor 49 Catalyst temperature Sensor 50 Vacuum sensor 51 Crank position sensor 51a Timing rotor 51b Electromagnetic pick-up 52 Water temperature sensor 301 Upper core 301a Flange 301b Through hole 302 Lower core 302a Flange 3 02b Through hole 303 Space 304 Bolt 305 Upper cap 305a Flange 306 Bolt 307 Lower cap 308 Upper coil 309 Lower coil 310 Armature shaft 311 Armature 312 Upper retainer 313 Adjusting bolt 314 Upper spring 315 Spring Seat 316 Lower spring 400 Bidirectional bus 401 CPU 402 ROM 403 RAM 404 Backup RAM 405 Input port 406 Output port 407 A / D T Top dead center B Bottom dead center L Cylinder center line P Axis φ

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Iwashita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kazuhiko 1 Toyota Motor Town Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Masashi Katsumada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masato Ogiso 1 Toyota Town Toyota City, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hideyuki Nishida Aichi Prefecture 1 Toyota Town, Toyota City Toyota Motor Corporation (72) Inventor Tomomi Yamada 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G084 BA05 BA15 BA23 CA09 DA11 FA00 FA07 FA10 FA11 FA20 FA29 FA38 3G092 AA01 AA05 AA11 BB06 CB02 DA01 DA03 DA11 FA05 GA17 HA01Z HA05Z HA06Z HD02Z HD05Z HE03Z HE0 8Z HF08Z 3G301 HA01 HA09 HA19 JA04 JA28 KA24 LA01 LA07 LB02 MA19 ND02 PA01Z PA07Z PA11Z PD02Z PD12Z PE03Z PE08Z PF03Z

Claims (4)

[Claims] 1. An intake port provided in a cylinder is branched on the downstream side to form a plurality of openings of an intake port facing a combustion chamber for each cylinder to increase a total opening area and to provide an intake valve in each of the openings. A fuel injection device is arranged upstream of the intake port, and during a specific engine operation, some of the intake valves and the remaining intake valves of the intake valves are stopped alternately in a closed state every specific period. When the part of the intake valves is in the stopped state, the remaining intake valves are operated and closed with the end of the intake stroke, and the remaining intake valves are in the stopped state. At some point, some of the intake valves are operated and closed at the end of the intake stroke.The intake valves that are currently operating but are scheduled to be stopped at the next intake stroke end the current intake stroke. After closing the valve with the fuel injection device Internal combustion engine to perform the injection control that. 2. The fuel injection device has a fuel injection timing controlled by fuel injection control means. The fuel injection control means operates the fuel injection device during an engine operation stroke during a compression stroke. The internal combustion engine according to claim 1, wherein: 3. The internal combustion engine according to claim 2, wherein the injection is performed at an early stage of a compression stroke. 4. The internal combustion engine according to claim 1, wherein an electromagnetically driven valve mechanism is applied to the valve mechanism of the intake valve.