JPH10317979A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain cycle variation of a gas flow and improve exhaust emission by nearly conforming swirl generated in a combustion chamber during the exhaust stroke to intake air swirl in the initial intake stroke, in an engine in which intake air swirl in the fixed direction is applied to the combustion chamber during the intake stroke. SOLUTION: Fuel is injected toward the recessed part 11 of a piston crown face 10 at after half of the compression stroke from a fuel injection valve 1 fitted to the intake side, so as to carry rich air-fuel mixture to an ignition plug 2 by swirl generated during the intake stroke, and at stratification operation, a swirl control valve on the exhaust side (SCV) 14 is closed. In this case, against that a SCV on the intake side 12 controls inflow of intake air from the intake valve 6B side into the cylinder 4 in the condition of closing the valve in order to generate swirl, when the exhaust side SCV 14 is closed, it controls back flow of exhaust from the exhaust valve 7A side into the cylinder 4. Thus, cycle variation of a gas flow is restrained, and deterioration of operability, misfire, and the like are prevented.

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 (in-cylinder direct fuel injection type or intake passage fuel injection) in which ignitability and combustion performance (such as combustion stability) are improved by utilizing intake swirl. Technology for all internal combustion engines, including internal combustion engines.

[0002]

2. Description of the Related Art A conventional direct-injection gasoline engine, which is a typical example of an internal combustion engine in which this type of intake swirl is used to improve ignition performance and combustion performance, is shown in FIG.
(See Japanese Patent Application Laid-Open No. 8-35429). The behavior of in-cylinder fuel in such a conventional in-cylinder direct injection gasoline engine is schematically shown in FIG.

That is, as shown in FIG. 9, in a conventional in-cylinder direct injection gasoline engine, during a partial load operation or the like, a swirl control valve provided in an intake port is closed and one cylinder is operated. On the other hand, the intake air is introduced into the combustion chamber (in the cylinder) from only one position (only the other intake valve) offset from the cylinder center by restricting the intake air from flowing into one of the two intake valves provided. By doing so, a swirl (swirl flow) is generated in the combustion chamber (in the cylinder).

Then, fuel F is injected from a fuel injection valve attached to the intake opening side of the combustion chamber toward the piston crown surface,
The fuel F is swirled by swirl along the side wall on the swirl downstream side of the concave portion provided on the intake side of the piston crown so that a rich mixture (stratified mixture) of a predetermined concentration can be transported to the ignition plug. Thus, even if the amount of supplied fuel is reduced (that is, the air-fuel ratio is increased to perform stratified combustion), the fuel efficiency is improved while ensuring good ignitability and combustion stability.

[0005]

However, in such a direct injection type gasoline engine, the amount of fuel supplied is small relative to the intake air flow rate (for homogeneous combustion or fuel injection type gasoline engine in the intake passage). ), It is necessary to ensure that the rich mixture reaches the spark plug. That is, in such a direct injection gasoline engine, when the cycle fluctuation of the swirling flow (swirl or the like) generated in the combustion chamber becomes large, the fuel F is transported largely depending on the gas flow in the cylinder. Because it is more susceptible to fluctuations than in-intake-path injection gasoline engines, fuel transport tends to be unstable due to swirl cycle fluctuations, resulting in poor drivability and misfires. There is a concern that exhaust emissions will increase.

For example, when the engine speed increases, the in-cylinder gas flow (for example, swirl) becomes stronger and the flow cycle fluctuation increases as compared with the low-speed side, so that the fuel is transported to the spark plug. There is a risk of instability.
As one of these causes, for example, as shown in FIGS. 10 and 11, when the valve overlap between the intake valve and the exhaust valve is small, the flow due to the extrusion of the exhaust gas generated in the combustion chamber during the exhaust stroke S3 is different from the flow S1 generated in the combustion chamber during the intake stroke (flow form,
It is conceivable that random disturbance is likely to occur in the intake air (flow S1) at the beginning of the intake stroke, and there is a high possibility of causing a subsequent cycle fluctuation of the gas flow.

Further, as shown in FIG. 12, when the intake pipe negative pressure is high and the valve overlap is large, the exhaust gas easily flows back into the combustion chamber from the exhaust pipe side. S1 is likely to be affected,
In addition, since the flow S2 due to the exhaust gas and the flow S1 of the intake air are different (because the flow form, direction, and the like are different), it is considered that the cycle fluctuation of the gas flow in the cylinder is easily caused. In addition, the mixing degree of the exhaust gas (residual gas) remaining in the cylinder and the fresh air may fluctuate, which may cause the fluctuation of the combustion cycle to increase.

The turbulence of the gas flow in the early stage of the intake stroke as described above continues to exist without disappearing until the latter stage of the intake stroke, and affects the ignition performance and the combustion performance. A similar concern arises not only in the injection type gasoline engine but also in other internal combustion engines in which intake swirl is used to improve ignition performance and combustion performance.

The present invention has been made in view of the above circumstances, and the ignition performance and the combustion performance fluctuate due to the cycle fluctuation of the in-cylinder gas flow, so that the drivability deteriorates and the exhaust emission increases due to misfire or the like. It is an object of the present invention to provide an internal combustion engine capable of suppressing such fears.

[0010]

Therefore, according to the first aspect of the present invention, in an internal combustion engine in which a swirling flow of intake air in a predetermined direction is supplied to a combustion chamber during an intake stroke, the internal combustion engine is provided with a swirling flow during an exhaust stroke. The generated swirl flow is made to substantially match the intake swirl flow in the predetermined direction at the beginning of the intake stroke.

According to the second aspect of the present invention, there is provided an intake-side swirl generating means for generating intake swirl, and an intake swirl flow in a predetermined direction is supplied to the combustion chamber during the intake stroke through the intake-side swirl generating means. The internal combustion engine includes exhaust swirl generation means for generating a swirl flow in the combustion chamber during the exhaust stroke so as to substantially match the intake swirl flow in the predetermined direction at the beginning of the intake stroke.

According to the first and second aspects of the present invention, the swirl flow generated in the combustion chamber during the exhaust stroke substantially matches the intake swirl flow in the predetermined direction at the beginning of the intake stroke. be able to. That is, as in the related art, a swirl flow generated in the combustion chamber during the exhaust stroke (a swirl flow caused by the exhaustion of the exhaust gas or a swirl flow caused by the backflow of the exhaust gas),
When the intake swirling flow (intake swirl) is different from the intake swirl flow (different in direction and number, etc.), the intake swirl (strength, direction, etc.) is greatly affected at the beginning of the intake stroke, and there is a possibility of random variation. However, according to the first and second aspects of the invention, such fear can be suppressed, and the intake air can be smoothly introduced into the combustion chamber without disturbing the intake swirl.

[0013] For this reason, since the cycle fluctuation of the gas flow can be suppressed, for example, in a direct injection type gasoline engine, the fuel injected in the latter half of the compression stroke can be stably transported to the spark plug. In addition, the mixing of the exhaust gas and the fresh air flowing backward in the cylinder is also made good, so that the fluctuation of the degree of mixing is suppressed, and thus the cycle fluctuation of the combustion state can be suppressed.

That is, according to the present invention, it is possible to suppress the unstable fuel transport and the unstable ignitability and combustibility due to the cycle fluctuation of the in-cylinder gas flow. It is possible to suppress fears such as deterioration and an increase in exhaust emission due to misfire or the like. Further, since the intake swirl flow and the exhaust swirl flow can be satisfactorily merged and mixed, for example, the mixing of the exhaust gas and the fresh air flowing backward from the exhaust side into the combustion chamber can be improved. Combustion can be obtained. Therefore, for example, the internal EGR amount (exhaust reverse flow rate) can be increased, and the amount of exhaust gas recirculated to the intake system via the EGR valve (external EGR amount) can be reduced.
The R system (eg, EGR valve) can be made more compact.

According to a third aspect of the present invention, the intake-side swirl generator has an intake port configured as a helical port. In the invention described in claim 4, the intake-side swirl generating means is configured as a means for mainly introducing intake air from one intake valve into the combustion chamber when one intake valve is provided with one cylinder. .

According to the third and fourth aspects,
The intake-side swirl generating means can be provided with a relatively simple and inexpensive configuration. In the invention described in claim 5, when the exhaust-side swirl generating means is provided with two exhaust valves in one cylinder, the exhaust-side swirl generating means in the predetermined direction generated by the intake-side swirl generating means among the two exhaust valves is provided. A means is provided for permitting communication between the combustion chamber and the outside air via an exhaust valve located downstream of the intake swirling flow, and for interrupting communication between the combustion chamber and the outside air via the other exhaust valve. I did it.

With this configuration, for example, an opening / closing valve (for example, an exhaust-side swirl control valve in FIG. 1 or an exhaust-side swirl control valve in FIG. 7) is provided on the exhaust downstream side of the exhaust valve. When the on-off valve is closed, the communication between the combustion chamber and the outside air via the exhaust valve located downstream of the intake swirling flow in the predetermined direction is relatively simple. With such a configuration, the exhaust-side swirl generating means can be provided.

In the invention according to claim 6, when the exhaust-side swirl generating means includes two exhaust valves,
One of the two exhaust valves is opened on the downstream side of the intake swirl flow in the predetermined direction generated by the intake-side swirl generation means to allow communication between the combustion chamber and the outside air, and the other exhaust valve Is configured to include means for closing the valve.

With this configuration, it is possible to provide the exhaust-side swirl generating means with a configuration in which the open / close state of the exhaust valve is switched without providing a special open / close valve or the like separately in the exhaust passage. Therefore, for example, this is a particularly effective technique for an internal combustion engine having a variable valve lift mechanism, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in the exhaust passage. . In addition, since the exhaust-side swirl control valve and the like exposed to the exhaust can be omitted, it is possible to promote reduction in reliability, cost, and the like.

In the invention described in claim 7, when the exhaust-side swirl generating means is provided with two exhaust valves in one cylinder, the exhaust-side swirl generating means generated by the intake-side swirl generating means of the two exhaust valves is provided. The opening / closing timing of the exhaust valve located downstream of the intake swirling flow in the predetermined direction is delayed from the opening / closing timing of the other exhaust valve, and the opening / closing timing of the exhaust valve located downstream of the intake swirling flow in the predetermined direction is adjusted by the intake valve. The opening / closing timing is overlapped for a predetermined period.

With this configuration, the exhaust-side swirl generating means can be provided by switching the opening / closing timing of the exhaust valve without providing a special on-off valve or the like separately in the exhaust passage. Therefore, for example, the technique is particularly effective in an internal combustion engine having a variable valve timing mechanism, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in an exhaust passage. .
In addition, since the exhaust-side swirl control valve and the like exposed to the exhaust can be omitted, it is possible to promote reduction in reliability, cost, and the like.

According to the eighth aspect of the present invention, when the exhaust-side swirl generating means includes two exhaust valves in one cylinder, the swirl flow generated in the combustion chamber in the latter half of the exhaust stroke is generated by the combustion of exhaust gas. Under conditions that are generated when being pushed out of the chamber to the outside, the exhaust valve located on the upstream side of the intake swirl flow in the predetermined direction generated by the intake-side swirl generating means among the two exhaust valves And means for permitting communication between the combustion chamber and the outside air via the other exhaust valve and cutting off communication between the combustion chamber and the outside air via the other exhaust valve.

In this way, for example, when the overlap period between the intake valve and the exhaust valve is short, even if a flow is formed by the extrusion of the exhaust during the exhaust stroke, the flow during the exhaust stroke is changed to the intake swirl. Therefore, it is possible to suppress the possibility that the intake swirl is disturbed in the early stage of the intake stroke, so that the cycle variation of the intake swirl can be reduced.

Therefore, according to the invention described in claim 8,
Even under the condition that the valve overlap is small, the fuel transport becomes unstable due to the cycle fluctuation of the in-cylinder gas flow and the combustion state becomes unstable, so that the drivability deteriorates, It is possible to suppress fears such as an increase in exhaust emissions due to misfire or the like.

According to a ninth aspect of the present invention, when the exhaust-side swirl generating means is provided with two exhaust valves in one cylinder, the swirl flow generated in the combustion chamber in the latter half of the exhaust stroke is generated by the combustion of exhaust gas. Under conditions that are generated when being pushed out of the chamber to the outside, the exhaust valve located on the upstream side of the intake swirl flow in the predetermined direction generated by the intake-side swirl generating means among the two exhaust valves Is opened to allow communication between the combustion chamber and the outside air, and at least at the latter stage of the exhaust stroke, the other exhaust valve is closed.

In this manner, in the same manner as in the eighth aspect of the invention, for example, when the overlap period between the intake valve and the exhaust valve is short, the flow due to the extrusion of the exhaust during the exhaust stroke is formed. In addition, since the flow during the exhaust stroke can be generated in substantially the same direction as the intake swirl, the possibility that the intake swirl is disturbed at the beginning of the intake stroke can be suppressed, and the cycle variation of the intake swirl can be reduced. be able to.

Therefore, according to the ninth aspect of the present invention, even under the condition where the valve overlap is small, the fuel transport becomes unstable or the combustion state becomes unstable due to the cycle fluctuation of the in-cylinder gas flow. Therefore, it is possible to suppress fears such as deterioration of drivability and an increase in exhaust emission due to misfire or the like.

Further, for example, the exhaust-side swirl control valve or the like is omitted, and one of the exhaust valves is closed during the exhaust stroke, or one of the exhaust valves is closed later in the exhaust stroke. This is a particularly effective technique for an internal combustion engine having a variable lift mechanism, and is effective when there is no space or the like where a special on-off valve or the like can be separately provided in the exhaust passage. In addition, since the exhaust-side swirl control valve and the like exposed to the exhaust can be omitted, it is possible to promote reduction in reliability, cost and the like.

[0029]

According to the first and second aspects of the present invention, the swirl flow generated in the combustion chamber during the exhaust stroke substantially matches the intake swirl flow in the predetermined direction at the beginning of the intake stroke. Can be Therefore, as in the related art, a swirl flow generated in the combustion chamber during the exhaust stroke (a swirl flow caused by the exhaust flow or a swirl flow caused by the exhaust back flow)
When the intake swirl and the intake swirl are different, the intake swirl (strength, direction, etc.) was greatly affected in the early stage of the intake stroke, and there was a possibility of random variation. And the intake air can be smoothly introduced into the combustion chamber.

Therefore, according to the present invention, it is possible to suppress instability in fuel transport and instability in ignitability and combustibility due to the cycle fluctuation of the in-cylinder gas flow. And the possibility that exhaust emissions increase due to misfire or the like can be suppressed. Further, since the intake swirl flow and the exhaust swirl flow can be satisfactorily merged and mixed, for example, the mixing of the exhaust gas and the fresh air flowing backward from the exhaust side into the combustion chamber can be improved. Combustion can be obtained. Therefore, for example, the internal EGR amount (exhaust reverse flow rate) can be increased, and the amount of exhaust gas recirculated to the intake system via the EGR valve (external EGR amount) can be reduced. Valves etc.) can be downsized.

According to the third and fourth aspects of the present invention, the intake-side swirl generating means can be provided with a relatively simple and inexpensive configuration. According to the fifth aspect of the present invention, the exhaust-side swirl generating means can be provided simply and inexpensively by, for example, an on-off valve provided on the exhaust downstream side of the exhaust valve.

According to the sixth aspect of the present invention, there is provided an exhaust-side swirl generating means in which the open / close state of the exhaust valve is switched without providing a special open / close valve or the like separately in the exhaust passage. Can be. Therefore, for example, this is a particularly effective technique for an internal combustion engine having a variable valve lift mechanism, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in the exhaust passage. . In addition, since the exhaust-side swirl control valve and the like exposed to the exhaust can be omitted, it is possible to promote reduction in reliability, cost, and the like.

According to the seventh aspect of the present invention, the exhaust-side swirl generating means is provided by switching the opening / closing timing of the exhaust valve without providing a special on-off valve or the like separately in the exhaust passage. Can be. Therefore, for example, the technique is particularly effective in an internal combustion engine having a variable valve timing mechanism, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in an exhaust passage. . In addition, since the exhaust-side swirl control valve and the like exposed to the exhaust can be omitted, it is possible to promote reduction in reliability, cost, and the like.

According to the eighth aspect of the present invention, under the condition that the overlap period between the intake valve and the exhaust valve is short,
Even if a flow due to the extrusion of the exhaust gas during the exhaust stroke is formed, the flow during the exhaust stroke can be generated in substantially the same direction as the intake swirl, so that the intake swirl may be disturbed at the beginning of the intake stroke. , The cycle fluctuation of the intake swirl can be reduced.

Therefore, even under the condition that the valve overlap is small, it is possible to prevent the fuel transport from becoming unstable and the combustion state from becoming unstable due to the cycle fluctuation of the in-cylinder gas flow. It is possible to suppress such concerns as deterioration of exhaust gas and an increase in exhaust emission due to misfire or the like. According to the ninth aspect of the present invention, similarly to the eighth aspect of the invention, for example, under the condition that the overlap period between the intake valve and the exhaust valve is short,
Even if a flow due to the extrusion of the exhaust gas during the exhaust stroke is formed, the flow during the exhaust stroke can be generated in substantially the same direction as the intake swirl, so that the intake swirl may be disturbed at the beginning of the intake stroke. , The cycle fluctuation of the intake swirl can be reduced.

According to the ninth aspect of the present invention as well, under the condition that the valve overlap is small, the fuel transport becomes unstable due to the cycle fluctuation of the in-cylinder gas flow, and the ignitability and the combustion state become unstable. Is suppressed, it is possible to suppress fears such as deterioration of drivability and an increase in exhaust emission due to misfire or the like. Further, for example, the exhaust-side swirl control valve or the like is omitted, and one of the exhaust valves is closed during the exhaust stroke, or one of the exhaust valves is closed at a later stage of the exhaust stroke. This is a particularly effective technique for an internal combustion engine provided with the above, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in the exhaust passage. In addition, since the exhaust-side swirl control valve and the like exposed to the exhaust can be omitted, it is possible to promote reduction in reliability, cost and the like.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
Description will be given based on the attached drawings. FIG. 1 (A), FIG.
(B) is a diagram showing a configuration of the first exemplary embodiment of the present invention. A fuel injection valve 1 is provided facing the combustion chamber (in the cylinder) 4 so that fuel can be directly injected and supplied into the combustion chamber 4 of the gasoline engine. The combustion chamber (inside the cylinder) 4 includes a crown surface 10 of the piston 3 inserted and held reciprocally in the cylinder liner 5, an inner wall of the cylinder liner 5, and a cylinder head 20.
And a lower surface of The ignition plug 2 for igniting the air-fuel mixture in the combustion chamber (in the cylinder) 4 is attached to the cylinder head 20 so as to face the combustion chamber (in the cylinder) 4.

The symbol F in the figure denotes fuel injected by the fuel injection valve 1 and is injected toward a concave portion 11 (see FIG. 2) provided on the intake side of the crown surface 10 of the piston 3. ing. An intake-side swirl control valve 12 as intake-side swirl generating means is provided inside the intake port 8, and inside the exhaust port 9,
An exhaust-side swirl control valve 14 is provided as exhaust-side swirl generating means. The intake-side swirl control valve 12 and the exhaust-side swirl control valve 14 are configured to open and close by being rotated via shafts 13 and 15, respectively. The shafts 13 and 15 are driven, for example, via an actuator (not shown) operated in response to a drive signal from an engine control unit (not shown).

The symbol S1 'in FIGS. 1A and 1B denotes a swirl generated in the combustion chamber 4 (in the cylinder) by the intake-side swirl control valve 12 or the exhaust-side swirl control valve 14. It is. here,
The operation in the present embodiment will be described. FIG. 3 schematically shows the behavior of the fuel in normal stratified operation.

Fuel is injected from the fuel injection valve 1 mounted on the intake side toward the concave portion 11 of the piston crown 10 in the latter half of the compression stroke, and the swirl S1 generated during the intake stroke causes the rich mixture to be ignited by the ignition plug 2. To be transported.
Then, as shown in FIG. 4, during the stratification operation, the exhaust-side swirl control valve 14 is closed so that the swirl S4 is generated by the exhaust-side swirl control valve 14 provided on the exhaust side.

More specifically, for example, the intake side swirl control valve 12 provided on the intake side restricts the flow of intake air from the intake valve 6B side into the cylinder 4 in a closed state to generate the swirl S1. On the other hand, when the exhaust-side swirl control valve 14 is closed, the exhaust gas 7A is restricted from flowing back into the cylinder 4 from the exhaust valve 7A side. That is, when the exhaust-side swirl control valve 14 is closed with respect to the swirl S1 generated by the intake air introduced into the cylinder 4 from the intake valve 6A when the intake-side swirl control valve 12 is closed. Exhaust valve 7
The swirl S4 generated when the exhaust gas flows backward from the side B into the cylinder 4 does not collide with each other, that is, the swirl direction of the swirl S1 and the swirl direction of the swirl S4 are substantially the same. Notches 12A of the control valve 12 and the exhaust-side swirl control valve 14,
14A are formed.

As described above, the swirl S4 generated by the exhaust-side swirl control valve 14 is directed in the same direction as the swirling direction of the intake swirl S1, so that as shown in FIG. Even if the gas flow S4 is generated at the beginning of the intake stroke due to the exhaust gas being sucked back (backflow) from the exhaust side, the gas flow S4 is in the same direction as the gas flow S1 on the intake side, so that the intake flow S1 is smoothly disturbed. Intake can be taken into the cylinder 4.

Therefore, the cycle fluctuation of the gas flow can be suppressed, so that the fuel injected in the latter half of the compression stroke can be stably transported to the ignition plug 2. In addition, since the mixing of the exhaust gas and the fresh air flowing backward in the cylinder is also good, the fluctuation of the degree of mixing is suppressed, and the cycle fluctuation of the combustion state can also be suppressed. Therefore, according to the present embodiment, the fuel transport becomes unstable due to the cycle fluctuation of the in-cylinder gas flow, and the combustion state is suppressed from becoming unstable, so that the operability deteriorates, It is possible to suppress fears such as an increase in exhaust emissions due to misfire or the like.

Further, according to the present embodiment, the following functions and effects can be obtained. That is, the intake swirl and the exhaust swirl can be satisfactorily merged and mixed by the exhaust-side swirl generating means.
Since the exhaust gas and the fresh air flowing backward from the exhaust side into the combustion chamber 4 can be mixed well, stable combustion can be obtained. Therefore, for example, the internal EGR amount (exhaust reverse flow rate) can be increased, so that the exhaust gas recirculation amount via the EGR valve to the intake system (external EGR amount) can be reduced. (Eg, an EGR valve) can be made compact.

Next, a second embodiment of the present invention will be described. In the second embodiment, the exhaust-side swirl generating means is provided with two exhaust valves 7 per cylinder during the exhaust stroke.
Of the valves A and 7B, the exhaust valve 7B on the side opposite to the intake port 8A that is not blocked by the intake-side swirl control valve 12 as intake-side swirl generating means (at a position symmetrical with respect to the center point of the combustion chamber) is greatly lifted. (Valve open)
(The exhaust valve 7A is substantially closed during the exhaust stroke). That is, by opening and closing the exhaust valves 7A and 7B as shown in FIG.
The exhaust swirl control valve 14 is omitted.

As a result, the swirl S4 generated by the exhaust gas flowing backward from the exhaust valve 7B side becomes the intake swirl S
In the initial stage of the intake stroke due to valve overlap, as shown in FIG.
The gas flow S is caused by the return of the exhaust gas from the exhaust side (backflow).
Even when 4 is generated, the direction is the same as that of the gas flow S1 on the intake side, so that the intake air can be smoothly drawn into the cylinder 4 without disturbing the intake flow S1.

Therefore, similarly to the first embodiment, the cycle fluctuation of the gas flow can be suppressed, so that the fuel injected in the latter half of the compression stroke can be stably transported to the ignition plug 2. become. In addition, since the mixing of the exhaust gas and the fresh air flowing backward in the cylinder is also good, the fluctuation of the degree of mixing is suppressed, and the cycle fluctuation of the combustion state can also be suppressed.

Thus, according to the present embodiment, unstable fuel transport and unstable combustion due to the cycle fluctuation of the in-cylinder gas flow are suppressed, resulting in poor operability. It is possible to suppress a fear that the exhaust emission is increased due to a fire or a misfire. According to the present embodiment, the exhaust-side swirl control valve 1 as in the first embodiment, which is exposed to exhaust gas, is used.
Since step 4 can be omitted, reduction in reliability, cost, and the like can be promoted. Also, the exhaust-side swirl generating means can be provided by a configuration in which the opening and closing timing of the exhaust valve is switched without providing a special on-off valve (exhaust-side swirl control valve or the like) separately in the exhaust passage. Therefore,
For example, this is a particularly effective technique for an internal combustion engine having a variable valve lift mechanism, and is also effective when there is no space or the like in which a special on-off valve or the like can be separately provided in the exhaust passage.

Further, according to the present embodiment, since the intake swirl and the exhaust swirl can be satisfactorily combined and mixed by the exhaust-side swirl generating means, the exhaust swirl flows back into the combustion chamber 4 from the exhaust side. Since the exhaust gas and the fresh air can be mixed well, stable combustion can be obtained. Therefore, for example, the internal EGR amount (exhaust reverse flow rate) can be increased, and the amount of exhaust gas recirculated to the intake system via the EGR valve (external EGR amount) can be reduced. (A valve etc.) can be made compact.

Next, a third embodiment according to the present invention will be described. In the third embodiment, as shown in FIG. 6, the exhaust-side swirl generating means is disposed on the side opposite to the intake port 8A which is not closed by the intake-side swirl control valve 12 as the intake-side swirl generating means (combustion chamber center point). The opening timing of the exhaust valve 7B is later than the opening timing of the other exhaust valve 7A,
In addition, the overlap period with the intake valves 6A and 6B is increased.

In this way, the intake swirl S1 and the exhaust-side swirl S4 can be generated in substantially the same direction at the beginning of the intake stroke, so that there is no fear that the intake air flow S1 will be disturbed at the beginning of the intake stroke. Therefore, the same operation and effect as those of the first and second embodiments can be obtained. In addition, since the configuration is such that the reverse flow of the exhaust gas from the exhaust valve 7B is allowed, the reverse flow rate of the exhaust gas can be reduced by the first and second embodiments. Since it can be increased compared to the second embodiment, the self (internal)
The EGR can be increased, so that the NOx emission can be more effectively reduced.

According to the present embodiment, since the exhaust-side swirl control valve 14 as in the first embodiment, which is exposed to the exhaust gas, can be omitted, it is possible to promote reduction in reliability and cost. Also, the exhaust-side swirl generating means can be provided by a configuration in which the opening and closing timing of the exhaust valve is switched without providing a special on-off valve (exhaust-side swirl control valve or the like) separately in the exhaust passage. Therefore, for example, the technique is particularly effective in an internal combustion engine having a variable valve timing mechanism, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in an exhaust passage. .

Next, a fourth embodiment according to the present invention will be described. In the fourth embodiment, as shown in FIG. 7, a cutout portion 14A of an exhaust-side swirl control valve 14 serving as an exhaust-side swirl generating means is replaced with a cutout portion of an intake-side swirl control valve 12 serving as an intake-side swirl generating means. It is arranged at a position facing the portion 12A (a position symmetrical with respect to the center line of the combustion chamber).

That is, when the valve overlap is small, there is almost no backflow of the exhaust gas from the exhaust valves 7A and 7B, so the influence of the backflow from the exhaust side on the intake swirl S1 is small. However, as described with reference to FIG. 10 and FIG.
Therefore, there is a high possibility that the exhaust flow S3 remains at the beginning of the intake stroke and affects the intake flow S1 at the beginning of the intake stroke.

Accordingly, in the present embodiment, the configuration as shown in FIG. 7 is adopted, and when the valve overlap is small,
Exhaust is extruded through the exhaust-side swirl generating means so that the flow S3 generated when the exhaust gas is discharged to the exhaust side (when it is pushed out) becomes a swirling flow similar to the swirl flow S1 of the intake air. Direction, thereby reducing the intake air swirl cycle variation.

That is, according to the present embodiment, as shown in FIG. 8, when the valve overlap is small, even if the flow S3 is formed by pushing out the exhaust during the exhaust stroke, the exhaust flow S3 is changed to the intake swirl. Since it is possible to cause the flow in the substantially same direction as S1, it is possible to suppress the possibility that the intake air flow S1 is disturbed in the initial stage of the intake stroke, so that the cycle variation of the intake swirl can be reduced.

Therefore, according to the present embodiment, even when the valve overlap is small, it is possible to prevent the fuel transportation from becoming unstable or the combustion state from becoming unstable due to the cycle fluctuation of the in-cylinder gas flow. Therefore, it is possible to suppress fears such as deterioration of drivability and an increase in exhaust emission due to misfire or the like. The exhaust-side swirl control valve 14 may be omitted and, for example, the exhaust valve 7B may be closed during the exhaust stroke, or at least the exhaust valve 7B may be closed at a later stage of the exhaust stroke. Flow S3 by extrusion
Can be generated in substantially the same direction as the intake swirl S1. Therefore, even if the exhaust-side swirl control valve 14 is omitted and the exhaust valve 7B is closed during the exhaust stroke, or the exhaust valve 7B is closed in the latter half of the exhaust stroke, the same as in the fourth embodiment. With this configuration, the exhaust-side swirl control valve 14 exposed to the exhaust can be omitted, so that reduction in reliability, cost, and the like can be promoted. Further, for example, if the exhaust-side swirl control valve or the like is omitted, and one of the exhaust valves is closed during the exhaust stroke, or one of the exhaust valves is closed at a later stage of the exhaust stroke, for example, a variable valve lift mechanism This is a particularly effective technique for an internal combustion engine provided with the above, and is effective when there is no space or the like in which a special on-off valve or the like can be separately provided in the exhaust passage.

In each of the above embodiments, a gasoline engine of a type that directly injects fuel into a cylinder (a so-called in-cylinder direct injection gasoline engine) has been described.
The present invention is not limited to this. Other engines that improve the ignitability and combustibility (such as combustion state) by using intake swirl, for example, a fuel injection gasoline engine in the intake passage or a direct engine The present invention can be applied to all engines, such as an injection type diesel engine, in which the fuel flow state (ignition degree between the intake swirl and the exhaust swirl) and the ignition state and the combustion state are easily affected by the gas flow in the cylinder. .

In each of the above embodiments, a case has been described in which two intake valves are provided and a swirl is generated by the intake-side swirl control valve. However, the present invention is not limited to this, and the intake swirl is generated. The present invention can be applied to, for example, a device provided with one intake valve per cylinder and a helical port as an intake port.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of the entire configuration according to a first embodiment of the present invention as viewed from below a cylinder head. (B)
1 is a cross-sectional view of the entire configuration according to a first embodiment of the present invention as viewed from the front.

FIG. 2 is a top view of the piston in the embodiment.

FIG. 3 is a schematic diagram showing the behavior of fuel during stratified combustion in the embodiment.

FIG. 4 is a view for explaining in-cylinder gas flow at the beginning of an intake stroke in the embodiment.

FIG. 5 is a diagram illustrating a valve lift and a timing characteristic according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a valve lift and a timing characteristic according to a third embodiment of the present invention.

FIG. 7 is a diagram showing an overall configuration according to a fourth embodiment of the present invention.

FIG. 8 is a view for explaining the in-cylinder gas flow from the exhaust stroke to the early stage of the intake stroke in the embodiment.

FIG. 9 is a diagram illustrating an example of a conventional direct injection gasoline engine.

FIG. 10 is a view for explaining the in-cylinder gas flow during the exhaust stroke when the valve overlap (O / R) is small.

FIG. 11 is a diagram for explaining the in-cylinder gas flow during the intake stroke when the valve overlap (O / R) is small.

FIG. 12 is a view for explaining in-cylinder gas flow during an intake stroke when valve overlap (O / R) is large.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel injection valve 2 spark plug 3 piston 4 combustion chamber (in cylinder) 5 cylinder liner (or cylinder block) 6 intake valve 6A, 6B intake valve 7 exhaust valve 7A, 7B exhaust valve 8 intake port 8A, 8B intake port 9 exhaust Port 9A, 9B Exhaust port 10 Piston crown 11 Recess 12 Intake side swirl control valve 14 Exhaust side swirl control valve

Claims (9)

[Claims] In an internal combustion engine, a swirl flow generated in a combustion chamber during an exhaust stroke is supplied to the intake air in the predetermined direction at an early stage of an intake stroke. An internal combustion engine characterized by substantially matching a swirling flow. 2. An internal combustion engine, comprising: intake side swirl generating means for generating intake swirl, wherein an intake swirl flow in a predetermined direction is supplied to a combustion chamber during an intake stroke via the intake side swirl generating means. An internal combustion engine comprising exhaust-side swirl generation means for generating a swirl flow in a combustion chamber during an exhaust stroke so as to substantially match an intake swirl flow in the predetermined direction at the beginning of a stroke. 3. The internal combustion engine according to claim 2, wherein said intake-side swirl generating means has an intake port configured as a helical port. 4. The intake-side swirl generating means is means for mainly introducing intake air from one intake valve into a combustion chamber when one intake valve is provided in one cylinder. The internal combustion engine according to claim 2. 5. When the exhaust-side swirl generating means has two exhaust valves in one cylinder, the exhaust swirl flow in the predetermined direction generated by the intake-side swirl generating means among the two exhaust valves is provided. It is characterized by including means for permitting communication between the combustion chamber and the outside air via an exhaust valve located on the downstream side, and cutting off communication between the combustion chamber and the outside air via the other exhaust valve. The internal combustion engine according to any one of claims 2 to 4, wherein 6. When the exhaust-side swirl generating means has two exhaust valves, the exhaust-side swirl generating means is provided downstream of the intake swirl flow in the predetermined direction generated by the intake-side swirl generating means among the two exhaust valves. The exhaust valve located at a position is opened to allow communication between the combustion chamber and the outside air, and the other exhaust valve is configured to include means for closing the valve. An internal combustion engine according to any one of the preceding claims. 7. When the exhaust-side swirl generating means includes two exhaust valves in one cylinder, the intake swirl flow in the predetermined direction generated by the intake-side swirl generating means out of the two exhaust valves. The opening / closing timing of the exhaust valve located on the downstream side is delayed from the opening / closing timing of the other exhaust valve, and the opening / closing timing of the exhaust valve located downstream of the intake swirling flow in the predetermined direction exceeds the opening / closing timing of the intake valve by a predetermined period. The internal combustion engine according to any one of claims 2 to 4, wherein the internal combustion engine is means for wrapping. 8. The exhaust-side swirl generating means is provided with two exhaust valves in one cylinder, and a swirl flow generated in a combustion chamber at a later stage of an exhaust stroke is when exhaust is pushed out of the combustion chamber to the outside. Under the condition that is generated in the two exhaust valves, the combustion chamber via an exhaust valve located on the upstream side of the intake swirl flow in the predetermined direction generated by the intake-side swirl generating means among the two exhaust valves. Allow communication with the outside air,
3. A system comprising means for shutting off communication between the combustion chamber and the outside air via the other exhaust valve.
The internal combustion engine according to claim 5. 9. When the exhaust-side swirl generating means includes two exhaust valves in one cylinder, a swirl flow generated in the combustion chamber in the latter half of the exhaust stroke is when exhaust gas is pushed out of the combustion chamber to the outside. Under the conditions that are generated in the combustion chamber, among the two exhaust valves, the exhaust valve located on the upstream side of the intake swirl flow in the predetermined direction generated by the intake-side swirl generating means is opened to open the combustion chamber. And means for permitting communication between the exhaust valve and the outside air and closing the other exhaust valve at least at the latter stage of the exhaust stroke. Item 8. The internal combustion engine according to any one of items 7.