JP2001003755A - Cylinder air flow generating method for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a vortex strength with high quality of a vortex kept, in a spark ignition engine intending to effect stratified combustion by using a vortex flow in a cylinder. SOLUTION: In this engine, a suction port 1 is provided with a partition wall 3 and a tumble control valve 6 and a suction valve 5 is opened and closed by electromagnetic solenoid 9a and 9b. In this case, during stratified operation, the tumble control valve 6 is half-opened and the closing timing of the suction valve 5 at the initial stage of a compression stroke is retarded. Tumble is reinforced by a tumble control valve and by effecting close-in-delay of the suction, air reversely flows to a suction port and a secondary vortex in a cylinder disappears. This constitution generates tumble of high quality even when a tumble control valve is in an intermediate opening state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for generating air flow in an internal combustion engine and a control device therefor.

[0002]

2. Description of the Related Art An internal combustion engine that performs lean combustion stably by generating a swirl flow in a cylinder during an intake / compression stroke and using the swirl flow to generate a mixture having a high fuel concentration around an ignition plug. For example, it is described in JP-A-6-159079. In this publication, a partition is provided in an intake port, a swirl vortex control valve is provided in one of the flow paths divided by the partition, and the tumble control valve is closed during low load operation to generate a tumble vortex in the cylinder. .

[0003] When the stratified operation is performed, the optimum swirling flow strength varies depending on the load condition and the number of revolutions of the engine. Therefore, it is necessary to adjust the swirling flow strength according to these conditions. is there. The method of adjusting the swirl flow generally adjusts the opening of the swirl flow control valve. In this case, as the opening of the swirl flow control valve decreases, the swirl flow in the cylinder increases (the swirl speed increases).

However, in the method of adjusting the swirling flow strength by the opening degree of the swirling flow control valve, when the opening degree of the swirling flow control valve is an intermediate opening degree, the quality of the generated swirling flow is greatly reduced. There's a problem. For example, according to the method of the above publication,
When the swirling flow control valve is set at the intermediate opening, a secondary vortex as shown in FIG. 13 is generated downstream of the intake valve. The secondary vortex is a vortex in a direction opposite to the rotation direction of the originally required swirling flow. Therefore, when the swirling flow is used for fuel stratification during lean burn, the secondary vortex may hinder the fuel supply around the spark plug or increase the adhesion of droplets to the piston crown surface. . As a result, there is a possibility of adverse effects such as deterioration of combustion stability during stratified operation and an increase in unburned hydrocarbon components and soot components in exhaust gas. In addition, since there is a large difference in air flow between the case where the swirl flow control valve is fully closed and the case where the swirl flow control valve is half open, it takes a lot of man-hours to optimize control parameters such as fuel injection timing, ignition timing, and control valve opening Can be considered. In view of this point, Japanese Patent Application Laid-Open No. 9-264149 proposes that the positional relationship between the lift amount of the intake valve and the mask surface be set to a specific form in order to enhance the tumble flow in a low / medium load region. Have been.

[0005]

However, the latter method has a problem in that once the positional relationship between the lift amount of the intake valve and the mask surface is determined, it cannot be corrected.

An object of the present invention is to make it possible to electrically control the degree of tumble reinforcement so that the degree of tumble reinforcement can be arbitrarily adjusted according to the type of engine and the operating state.

[0007]

In order to achieve the above object, the present invention provides an intake port opened to a combustion chamber, an intake valve engaged with the intake port, a variable valve mechanism for opening and closing the intake valve, and In an internal combustion engine provided with a tumble adjustment mechanism for adjusting the strength of the swirl flow generated in the cylinder, when the engine has a low or medium load, the swirl flow of the combustion chamber is enhanced by the swirl flow adjustment mechanism. A method for generating in-cylinder air flow of an internal combustion engine, characterized in that a closing timing of an intake valve is made later than a closing timing of a high load operation by the variable valve mechanism. Preferably, the swirling flow adjusting mechanism is a swirling flow adjusting mechanism including a partition plate that partitions a cross section of the intake port into a plurality of sub-flow paths and a swirling flow control valve that changes distribution of air flow to the sub-flow paths.

Preferably, the swirling flow adjusting mechanism is an independent sub-flow passage having a cross-sectional area smaller than a cross-sectional area of the intake port, and an inlet of the sub-flow passage is connected to an upstream portion of the intake port;
This is a swirling flow control mechanism configured with a swirling flow control valve that directs the outlet of the sub flow path to the inside of the cylinder and changes the distribution of air flow flowing through the sub flow path and the intake port.

Preferably, the internal combustion engine is characterized in that there are a plurality of intake ports opening to the combustion chamber, and the swirling flow adjusting mechanism is a swirling flow control valve for changing an air flow distribution of the plurality of ports.

[0010] Preferably, there is provided a method for generating in-cylinder air flow of an internal combustion engine, wherein the closing timing of the intake valve at the time of low engine load of the engine is changed according to the required strength of the swirling flow.

Preferably, there is provided a method for generating in-cylinder air flow of an internal combustion engine, characterized in that a closing timing of an intake valve at a low engine load is changed in conjunction with a swirling flow control valve.

Preferably, at the time of low to medium load operation of the engine,
In-cylinder air flow of an internal combustion engine, wherein control is performed to close an intake valve engaged with an intake port controlled so that an air flow rate is minimized in an intake stroke by the swirl flow control valve later than other intake valves. It is a generation method.

According to the present invention, there are provided a plurality of intake ports opening to a combustion chamber, intake valves engaged with the intake ports, a variable valve mechanism for opening and closing the intake valves, and adjusting the strength of a swirling flow generated in the cylinder. In an internal combustion engine provided with a swirling flow adjusting mechanism, when the engine is at a low to medium load, the swirling flow adjusting mechanism is operated so that the swirling flow intensity is maximized, and a request at a low and medium load of the engine is made. A method for generating in-cylinder air flow of an internal combustion engine, characterized in that a maximum lift amount of an intake valve is changed by the variable valve according to the strength of a swirling flow.

Preferably, the swirling flow adjusting mechanism comprises a partition plate for partitioning the cross section of the intake port into a plurality of sub-flow paths, and a valve capable of shutting off air from flowing into any of the sub-flow paths. A method for generating in-cylinder air flow of an internal combustion engine, wherein the valve is controlled so as to shut off the flow of air into the sub flow path during operation.

Preferably, the swirling flow adjusting mechanism has an independent sub-flow passage having a smaller cross-sectional area than the intake port, an inlet connected to the upstream portion of the intake port, and an outlet directed to the inside of the cylinder. An in-cylinder air flow generation method for an internal combustion engine, comprising a valve capable of shutting off air inflow, and controlling the valve to shut off air inflow to a sub-flow path during low-medium load operation of the engine.

According to the present invention, in an internal combustion engine provided with an intake port opening to a combustion chamber, an intake valve engaged with the intake port, and a variable valve mechanism for opening and closing the intake valve, a wall length of a valve seat portion of the intake port is provided. Is different in the circumferential direction of the intake valve, and at low and medium load operation, the intake valve lift is changed according to the strength of the required swirling flow within the range of the valve lift that does not open the entire circumference of the intake valve. And a method for generating in-cylinder air flow of an internal combustion engine.

Preferably, a method for generating in-cylinder air flow of an internal combustion engine is characterized in that the lift amount of the intake valve is changed so that the entire circumference of the intake valve is opened during high load operation.

When the engine is operating at low to medium load, a swirling flow is generated in the cylinder by the swirling flow adjusting mechanism. The secondary vortex generated at this time is discharged from the combustion chamber to the intake port by making the closing timing of the intake valve later in the compression stroke than during high load operation by the variable valve mechanism. As a result, a high-quality swirl flow without secondary vortices can be generated.

When the swirling flow adjusting mechanism is operated so as to maximize the swirling flow strength, a high-quality swirling flow having no secondary vortex in the cylinder is generated. Further, by changing the maximum lift amount of the intake valve by a variable valve according to the strength of the required swirling flow, the strength of the swirling flow can be adjusted according to the operating conditions without deteriorating the quality of the swirling flow. Can be set to strength.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of the present invention. In FIG. 1, reference numeral 2 denotes a combustion chamber of an engine, 4 denotes a piston having a concave surface, 1 denotes an intake port, 5 denotes an intake valve, 13 denotes a fuel injection valve, and 14 denotes a spark plug. Partition wall 3 for intake port 1
The interior of the intake port 1 is divided into an upper passage 1a and a lower passage 1b. A tumble control valve 6 is provided upstream of the lower passage 1b. This tumble control valve 6
Is opened and closed by a pulse motor 7. The valve opening of the tumble control valve 6 is determined by a valve opening signal 7a sent from the controller 8.
Is sent to the motor drive circuit 10b, and the motor drive circuit 10b
The number of the pulse signals 7b corresponding to the valve opening degree from b is input to the pulse motor 7 to be adjusted. The intake valve 5 is driven by an electromagnetic force. That is, a voltage is applied to the electromagnetic solenoids 9a and 9b by the drive circuit 10a, the movable portion 11 moves up and down by the electromagnetic force, and the intake valve 5 connected thereto opens and closes. Solenoid drive circuit 10a
Adjusts the voltage applied to the solenoids 9a and 9b based on the intake valve lift signal 12a sent from the controller 8 so that the lift of the intake valve becomes a required value.

In FIG. 1, the exhaust port and the exhaust valve are not shown.

FIG. 2 shows an operation mode with respect to the engine speed and the torque. When the engine speed and the torque are lower than predetermined values, that is, when the load is low and medium, lean burn operation is performed to reduce fuel consumption. Since the air-fuel ratio at this time is usually set to about 40, a stratification operation is performed in which fuel is concentrated around the spark plug to stably ignite the air-fuel mixture. During high-load operation, homogeneous stoichiometric operation is performed. At the boundary between the homogeneous stoichiometry and the stratified lean operation, a homogeneous lean operation is performed to eliminate a torque step caused by the operation switching.

The engine in this embodiment is a direct injection engine, and operates in the stratified operation mode, for example, as shown in FIG. That is, (a) the tumble control valve 6 is closed and the intake valve 5 is opened immediately before the intake stroke.
By closing the tumble control valve 6, air passes through the upper passage 1 a and is introduced into the combustion chamber 2 from above the intake valve 5. Thereby, a counterclockwise tumble TR1 is generated in the combustion chamber. (B) At the beginning of the compression stroke, the intake valve 5 is closed, and fuel is injected by the fuel injection valve 13 at the end of the compression stroke. (C) The fuel is vaporized and transported around the ignition plug 14 at the upper part of the combustion chamber by the tumble in the combustion chamber and stratified.

When stratification is performed by such a method, the optimum tumble strength varies depending on the operating conditions of the engine. For example, when the engine rotates at a high speed, the speed of the intake air is high, so the tumble turning speed is high. Conversely, when the engine is at a low speed, the tumble turning speed decreases. It is considered that the fuel vaporization time does not greatly change even if the rotational speed changes. Therefore, a certain vaporization time is required after the fuel is injected until the fuel reaches around the spark plug.
Therefore, it is necessary to control the turning speed of the tumble to be slow during high-speed rotation and to be fast during low-speed rotation. Further, when the engine torque changes, the amount of air taken in changes, so that the tumble strength changes. Therefore,
In order to perform stratified lean operation in a wide operating range, it is necessary to set the optimum tumble strength according to the operating conditions of the engine.

The tumble strength is controlled by the opening of the tumble control valve 6, as shown in FIG. Here, the tumble number is a ratio between the angular speed of the tumble and the angular speed of the crankshaft of the engine.

When the tumble control valve 6 is fully closed, air is sucked only from the upper passage 1a, so that the flow velocity of air entering the combustion chamber through the upper side of the intake valve is increased, and a large angular momentum is generated in the cylinder. I do. Therefore, the number of tumbles is maximized.

As the tumble control valve is opened, the upper flow path 1
Since the air flow rate a decreases and the air flow rate increases in the lower flow path 1b, the flow velocity of air entering the combustion chamber through the upper side of the intake valve decreases, and the number of tumbles decreases.

To determine the opening of the tumble control valve in accordance with the operating conditions of the engine without increasing the calculation load,
As shown in Table 1, a table of the tumble control valve opening degree with respect to the engine speed and the engine torque may be prepared in advance.

The opening of the tumble control valve 6 is determined by a tumble control valve opening signal 7a sent from the control device 8 to the motor drive circuit 10b.

When the controller 8 determines that the operation mode is the stratified operation mode based on the relationship between the number of revolutions of the engine and the engine torque, the controller 8 refers to the table shown in Table 1 to determine the optimum tumble number. The opening of the valve tumble control valve 6 is determined.

FIG. 5 shows a change in the lift amount of the intake valve 5 in this embodiment. In the present embodiment, two intake valve lift patterns are switched as shown in FIGS. 5A and 5B according to the operating conditions of the engine. The intake valve lift patterns (a) and (b) have the same maximum lift amount and valve opening timing, but differ in valve closing timing. In (b), the valve closing timing is retarded compared to (a). .

The closing timing of the intake valve is determined by the processing procedure shown in FIG. First, an engine operation mode is selected from the engine speed and the engine torque according to the map shown in FIG. Here, the engine torque is usually estimated from the accelerator opening, the vehicle speed, the position of the transmission, and the like. When the operation other than the stratified lean burn operation is selected, the intake valve lift pattern of FIG. 5A that does not retard the intake valve closing timing is adopted. When stratified lean burn operation is selected, the table shown in Table 1 is searched, and based on the engine speed and torque,
Find the required tumble control valve opening. Here, when it is determined that the tumble control valve is not fully closed, the intake valve lift pattern of FIG. 5B for retarding the valve closing timing is employed. When it is determined that the tumble control valve is fully closed, the intake valve lift pattern of FIG. 5A that does not retard the valve closing timing is employed. That is, the closing timing of the intake valve is retarded only in the stratified lean burn operation and when the tumble control valve is half-open.

[0034]

[Table 1]

FIG. 1 shows the air flow during the intake and compression strokes when the intake valve closing timing is retarded. Before the start of the intake stroke, the control device 8 sets the tumble control valve 6 to a predetermined opening degree, and the control device 8 opens the intake valve 5.

Since the tumble control valve 6 is in a half-open state,
In the intake stroke, air flows into the cylinder from both the upper passage 1a and the lower passage 1b. As a result, FIG.
As shown in (b), a counterclockwise tumble TR1 and a clockwise tumble TR2 are generated.

Since the inlet of the lower flow path 1b is restricted by the tumble control valve 6, the air flow rate in the upper flow path 1a is larger than that in the lower flow path 1b. Therefore, the counterclockwise angular momentum of TR1 is larger than the clockwise angular momentum of TR2, and a counterclockwise tumble component is generated as an average of the entire combustion chamber.

In the compression stroke, the closing timing of the intake valve 5 is retarded. As shown in FIG. 1 (c), the air in the cylinder whose pressure has increased with the rise of the piston passes under the intake valve 5. Then, it flows backward into the lower flow path 1b. On the other hand, the upper channel 1
Since a has a larger air flow rate and flow velocity than the lower flow path 1b, the inertia force of the air is larger, and even if the back flow BF starts to occur in the lower flow path 1b, no back flow occurs in the upper flow path 1a. Lower channel 1b
The counterclockwise tumble TR2 generated below the intake valve 5 disappears due to the backflow BF at the time of the compression stroke.
As shown in (d), only the counterclockwise tumble TR1 is formed. Thus, only the strength of the tumble can be changed by adjusting the opening of the tumble control valve without causing the quality of the tumble to deteriorate due to the secondary vortex.

The retard period for closing the intake valve is as follows:
It may be changed according to the required number of tumbles. When the required tumble number is small, the opening of the tumble control valve 6 is large, and the amount of air entering the combustion chamber through the lower passage 1b increases. Therefore, the clockwise tumble TR2 becomes stronger. Therefore, if the retard period Δθ of the intake valve closing timing is increased as the opening of the tumble control valve increases as shown in FIG. 7, the secondary vortex component can be eliminated more reliably. Further, as the retard period Δθ of the intake valve closing timing becomes longer, the backflow to the intake port increases, so that the charging efficiency in the combustion chamber decreases. To prevent this, FIG.
As shown in (b), the air amount may be adjusted by increasing the throttle valve opening TH as the intake valve retard period Δθ becomes longer. Thus, it is possible to prevent a decrease in torque due to retarding the closing timing of the intake valve. In the present embodiment, the intake valve is electromagnetically driven. However, even in the case of cam drive, the closing timing of the intake valve can be retarded by combining a plurality of cam shapes, and the same air flow can be generated. Also, as shown in FIG. 7C, the same effect can be obtained by retarding the entire lift pattern of the intake valve.

As a method of generating the tumble, a method of providing a bypass flow path 20 having a smaller sectional area than the intake port 1 in the intake port 1 as shown in FIG. Even when such a bypass flow path 20 is provided, the opening degree of the tumble control valve 6 is set according to the required number of tumbles, and the closing timing of the intake valve 5 is retarded. And a high quality tumble can be generated.

FIG. 9 shows an example in which the present invention is applied to a swirl (lateral vortex) generation technique. In the present embodiment, two intake ports 1c and 1d are provided in the combustion chamber 2, and intake valves 5c and 5d driven by electromagnetic solenoids 9a and 9b are provided in the respective intake ports. A swirl control valve 6b driven by a step motor 7 is provided in the intake port 1d. The opening degree of the swirl control valve 6b is changed according to the required swirl number, and a predetermined swirl number is obtained. Swirl control valve 6
When b is an intermediate opening, a secondary vortex component SW2 is generated near the outlet of the intake port 1d. However, the secondary vortex component SW2 is generated by retarding the closing timing of the intake valves 5c and 5d as in the case of the tumble generation. A reverse flow is generated in the intake port on the side where the vortex SW2 is generated, and a high-quality swirl having no secondary vortex component can be generated. In this embodiment, the same effect can be obtained even if only the intake valve 5d is retarded.

Next, a second embodiment of the present invention is shown in FIG. In this embodiment, the intake valve 5 is opened and closed by hydraulic pressure. When opening the intake valve 5, the valve 22 is opened and the valve 23 is closed. The hydraulic pressure pressurized by the hydraulic pump 21 is supplied to the hydraulic cylinder 24 and the intake valve 5
Is pushed down. When closing the intake valve 5, the valve 22
Is closed, and the valve 23 is opened. As a result, the oil in the hydraulic cylinder 24 is released, and the spring 25 pushes up the intake valve 5 to close it. The maximum lift amount of the intake valve 5 is determined by the balance between the hydraulic pressure supplied to the hydraulic cylinder 24 and the restoring force of the spring 25. That is, when the opening of the valve 22 is increased and the opening of the valve 23 is decreased, the hydraulic pressure supplied to the hydraulic cylinder 24 increases, and the maximum lift of the intake valve 5 increases. Conversely, when the opening of the valve 22 is reduced and the opening of the valve 23 is increased, the hydraulic pressure in the hydraulic cylinder 24 decreases, and the maximum lift of the intake valve 5 decreases. In the present embodiment, the opening degrees of the valves 22 and 23 are adjusted by the valve opening signals 22a and 23a sent from the control device 8, and the maximum lift amount of the intake valve 5 is arbitrarily changed.

In this embodiment, when the stratified lean burn operation is selected and tumble generation is required, the tumble control valve 6 is fully closed and the intake valve 5 is opened. As a result, as shown in FIG. 10B, air is sucked into the combustion chamber 2 only from the sub flow path 1a. Therefore, no secondary vortex component is generated in the combustion chamber 2 due to the airflow entering from the sub flow path 1b, and a high-quality tumble is generated in the compression stroke as shown in FIG. In the present embodiment, the number of tumbles is controlled by the maximum lift amount of the intake valve 5. FIG. 11A shows a change in the number of tumbles with respect to the maximum lift amount Lmax of the intake valve 5. When Lmax is very small, the pressure loss at the intake valve is large and the number of tumbles is small. As Lmax increases, the number of tumbles becomes Lmax = Lp
When the peak value is taken and Lmax is further increased, the number of tumbles decreases. This is because, when the lift amount of the intake valve increases, the opening area at the intake valve portion increases, and the intake flow velocity decreases. If the relationship between the maximum lift of the intake valve and the number of tumbles is obtained in advance, a flow with an arbitrary number of tumbles can be generated by changing the maximum lift of the intake valve. If the relationship between the lift amount of the intake valve and the number of tumbles is stored in a table in advance, the maximum lift amount of the intake valve with respect to the required number of tumbles can be easily obtained. As a method of selecting the valve lift amount with respect to the number of tumbles, the relationship becomes a quadratic curve as shown in FIG.
There are two possible choices, the smaller side and the side larger than Lp. In order to secure the required intake air amount, it is necessary to reduce the pressure loss at the intake valve.
It is desirable to select the side with the larger intake valve lift as shown in (b). Therefore, when the maximum lift amount of the intake valve is reduced as shown by the dotted line in FIG.
As shown in FIG. 0 (b), the flow velocity of air entering the combustion chamber 2 from the sub flow path 1a increases, and a large number of tumbles is obtained. When the maximum lift amount of the intake valve is increased as in the practice of FIG. 11B, as shown in FIG. 10C, the flow velocity of the air entering the combustion chamber 2 from the sub flow path 1a becomes slow and the number of tumbles becomes small. .

In other words, in the present embodiment, when the tumble is generated, the tumble control valve 6 is fully closed before the intake stroke to create air flow without secondary vortices, and the intake valve 5 is adjusted so that the required number of tumbles is obtained. Set the maximum lift.

As a tumble generation method, a flow shield 50 may be provided at the outlet of the intake port 1 as shown in FIG. According to this method, the lift amount of the intake valve 5 is reduced
In a range smaller than the height of 0, the shield side of the intake valve is always closed, so that the same effect as in the embodiment shown in FIG. 10 in which the tumble control valve 6 is fully closed can be obtained. That is, since air is sucked only from above the intake valve 5 (the side without the shield 50), a tumble can be generated without creating a secondary vortex in the combustion chamber. Further, when the engine is under a high load and tumble generation is not necessary, FIG.
As shown in (c), the lift amount of the intake valve 5 is reduced by the shield 50.
Larger than the height of As a result, the shield 5 of the intake valve 5
Air flows in from the zero side, and air can be efficiently inhaled.
According to this method, there is no need to provide a tumble control valve and a partition in the intake port, and there is an advantage that the tumble can be controlled only by the lift amount of the intake valve.

Also in the case of swirl, the tumble is achieved by a combination of an intake valve provided with a variable lift mechanism and an intake port provided with a swirl generating mechanism as shown in FIG. 9 or a shield shown in FIG. As in the case, high-quality swirls can be generated with an arbitrary number of swirls.

[0047]

According to the present invention, it is possible to arbitrarily set the strength of the swirling flow generated in the combustion chamber during low-medium load operation without deteriorating the quality of the swirling flow. This improves the combustion stability and lean limit during stratified operation. Also, since the quality of the swirl flow is always kept constant regardless of the strength of the swirl flow,
This facilitates control design of the intake and fuel supply systems, and has advantages such as cost reduction and shortened development time.

[Brief description of the drawings]

FIG. 1 is a configuration of an engine showing an embodiment of the present invention.

FIG. 2 is a rotation speed and torque map in the embodiment.

FIG. 3 is an outline of operation during stratified operation in the embodiment.

FIG. 4 is an example of a relationship between a tumble control valve and the number of tumbles.

FIG. 5 shows an example of an intake valve operating method.

FIG. 6 shows a method for determining an intake valve retard.

FIG. 7 shows the relationship between the intake valve retard amount and the tumble control valve opening.

FIG. 8 shows an example of a tumble generation method.

FIG. 9 shows an example of a swirl generation method.

FIG. 10 is a configuration of an engine showing an embodiment of the present invention.

FIG. 11 shows the relationship between the intake valve lift and the number of tumbles.

FIG. 12 shows an example of a tumble generation method.

FIG. 13 shows an example of a conventional method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Intake port, 2 ... Combustion chamber, 3 ... Partition wall, 5 ... Intake valve,
6 ... tumble control valve, 8 ... control device, 9a, 9b ... electromagnetic solenoid.

Continued on the front page (72) Inventor Takuya Shiraishi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Yoko Nakayama 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Yusuke Kihara 1-1-1, Omikamachi, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Noboru Tokuyasu 7, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 in the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (12)

[Claims] An intake port opening to a combustion chamber, an intake valve engaged with the intake port, a variable valve mechanism for opening and closing the intake valve,
In an internal combustion engine provided with a swirl flow adjusting mechanism for adjusting the strength of the swirl flow generated in the cylinder, when the engine has a low and medium load, the swirl flow of the combustion chamber is enhanced by the swirl flow adjusting mechanism. A method for generating in-cylinder air flow of an internal combustion engine, wherein the closing timing of the intake valve is made later than the closing timing of the high load operation by the variable valve mechanism. 2. The swirling flow adjusting mechanism according to claim 1, wherein the swirling flow adjusting mechanism includes a partition plate that partitions a cross section of the intake port into a plurality of sub-flow passages, and a swirl flow control valve that changes an air flow distribution to the sub-flow passages. An internal combustion engine characterized by: 3. The suction flow adjusting mechanism according to claim 1, wherein the swirling flow adjusting mechanism is an independent sub-flow passage having a cross-sectional area smaller than a cross-sectional area of the intake port, and an inlet of the sub-flow passage is connected to an upstream portion of the intake port. An internal combustion engine characterized by comprising a swirl flow control valve whose outlet of the sub flow path is directed toward the inside of the cylinder and changes distribution of air flow flowing to the sub flow path and the intake port. 4. An internal combustion engine according to claim 1, wherein a plurality of intake ports are opened to the combustion chamber, and said swirling flow adjusting mechanism is a swirling flow control valve for changing an air flow distribution of said plurality of ports. . 5. The method according to claim 1, wherein the closing timing of the intake valve when the engine is under low and medium load is changed according to the required strength of the swirling flow. 6. The method according to claim 1, wherein the closing timing of the intake valve at the time of low and medium load of the engine is changed in conjunction with the swirling flow control valve. 7. The intake valve according to claim 4, wherein the intake valve engaged with the intake port controlled by the swirl flow control valve so as to minimize the air flow during the intake stroke during low-medium load operation of the engine is different from other intake valves. A method for producing in-cylinder air flow of an internal combustion engine, comprising performing late closing control. 8. A plurality of intake ports opened to a combustion chamber, intake valves engaged with the intake ports, a variable valve mechanism for opening and closing the intake valves, and adjusting the strength of a swirl flow generated in the cylinder. In an internal combustion engine provided with a swirl flow adjusting mechanism, when the engine has a low to medium load, the swirl flow adjusting mechanism is operated so that the swirl flow intensity is maximized,
A method for generating in-cylinder air flow of an internal combustion engine, wherein the maximum valve lift of an intake valve is changed by the variable valve according to the strength of a required swirl flow at low engine load. 9. The swirling flow adjusting mechanism according to claim 8, wherein the swirling flow adjusting mechanism comprises a partition plate for partitioning a cross section of the intake port into a plurality of sub-flow paths, and a valve capable of blocking air from flowing into any of the sub-flow paths. , When the engine is running at low and medium load
A method for producing in-cylinder air flow of an internal combustion engine, wherein the valve is controlled so as to shut off the inflow of air into the sub flow path. 10. An independent sub-flow path according to claim 8, wherein the swirling flow adjusting mechanism has a smaller sectional area than the intake port, the inlet is connected to the upstream portion of the intake port, and the outlet is directed to the inside of the cylinder. A valve capable of shutting off air inflow into the flow passage, and controlling the valve to shut off air flow into the sub flow passage during low-medium load operation of the engine; Law. 11. An internal combustion engine provided with an intake port opened to a combustion chamber, an intake valve engaged with the intake port, and a variable valve mechanism for opening and closing the intake valve, wherein a wall length of a valve seat portion of the intake port is reduced. It is characterized in that it differs in the circumferential direction of the intake valve and changes the intake valve lift amount according to the strength of the required swirling flow within the range of valve lift amount that does not open the entire circumference of the intake valve at low and medium load operation. Cylinder air flow generation method for an internal combustion engine. 12. The method according to claim 11, wherein the amount of lift of the intake valve is changed so that the entire circumference of the intake valve is open during high load operation.