JPH10325330A - Direct cylinder fuel injection type spark ignition internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable super lean combustion by stratified burning while ensuring an output when a throttle is fully opened. SOLUTION: A device is provided with a fuel injection valve arranged facing to a combustion chamber, a plurality of intake ports 8, 9 which are independent from each other and communicated with the combustion chamber through intake valves 4A, 4B, and swirl control valves 10, 11 which are synchronously opened and closed and are arranged on the intake ports 8, 9. A cutout part 10A is arranged on either one of the swirl control valves 10, 11, and the swirl control valves 10, 11 are closed at the time of stratified burning so as to generate swirl smoothly. At the time of homogeneous combustion such when a throttle is fully opened, a valve is opened, and a suction operation is carried out by two straight ports so as to easily ensure the same output as a prior MPI type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a direct cylinder injection type spark ignition internal combustion engine employed in a vehicle or the like.

[0002]

2. Description of the Related Art Conventionally, as a vehicle internal combustion engine, a direct cylinder injection type spark ignition internal combustion engine in which fuel is injected directly into a combustion chamber and then ignited by an ignition plug is known. JP-A-8-35429 and the like.

[0003] In this method, two independent intake ports are formed, one of the intake ports is provided with a swirl control valve that can be opened and closed, and the other intake port is formed by a helical port that generates a swirl flow in a combustion chamber. You.

[0004] A concave portion is provided on the top surface of the piston, and a fuel injection valve is arranged in the combustion chamber so as to inject fuel toward the concave portion.

[0005] When the air-fuel ratio is on the super lean side (for example, A / F ≧ 4
In the running state in which the fuel consumption is reduced to 0), stratified combustion in which a gas having an ignitable air-fuel ratio is performed near the ignition plug is performed. At the time of stratified combustion, the swirl control valve is closed, and intake is performed only from the helical port to generate a swirl flow in the piston recess.The injected fuel is guided to the vicinity of the ignition plug by the swirl flow, Performs ultra-lean combustion stably.

On the other hand, when a driving torque is required during acceleration or the like, homogeneous combustion is performed to set the air-fuel ratio to the stoichiometric air-fuel ratio or the rich side. At the time of this homogeneous combustion, the swirl control valve is opened to intake air from the two intake ports, and the intake air amount corresponding to the increased amount of fuel is secured to perform combustion at the stoichiometric air-fuel ratio or the rich side.

[0007]

However, in the above-mentioned conventional direct in-cylinder injection spark ignition internal combustion engine, one of the two independent ports is a helical port, so that the driving torque during acceleration or the like is reduced. If necessary,
When the throttle is fully opened, the generation of swirl by the helical port becomes a resistance, and compared to a conventional internal combustion engine that injects fuel into an intake pipe (hereinafter referred to as an MPI internal combustion engine = a multipoint injector internal combustion engine). In order to compensate for this decrease in output, a means for increasing output such as a variable valve timing system is required, which causes a problem that the structure of the engine becomes complicated and manufacturing costs increase.

The present invention has been made in view of the above problems, and an object of the present invention is to enable super-lean combustion by stratified combustion while obtaining the same output as a conventional MPI internal combustion engine when the throttle is fully opened. And

[0009]

According to a first aspect of the present invention, there is provided a fuel injection valve disposed facing a combustion chamber, a plurality of independent intake ports communicable with the combustion chamber via an intake valve, and Direct in-cylinder injection provided with a swirl generating means disposed in the intake port to generate swirl in the combustion chamber, a concave portion formed in the top surface of the piston, and an ignition plug disposed in a position facing the concave portion In the spark-ignition internal combustion engine, the plurality of intake ports are each constituted by a straight port, and the swirl generating means is constituted by a swirl control valve disposed at each intake port and capable of being opened and closed synchronously. One of the swirl control valves includes a flow path cross-sectional area reducing portion that allows passage of intake air even when the valve is closed.

According to a second aspect of the present invention, in the first aspect, the recess is formed facing the intake valve, and the spark plug is disposed at a position capable of facing the inner peripheral side of the recess. 2. The direct in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the fuel injection valve is provided to inject fuel toward the recess.

In a third aspect based on the second aspect, the fuel injection valve injects the fuel in a conical shape and sets the fuel injection angle to a predetermined value between 50 ° and 90 °. .

[0012] In a fourth aspect based on the first aspect, the swirl control valve is closed during stratified combustion, is opened during homogeneous combustion, and shifts from stratified combustion to homogeneous combustion or vice versa. At this time, a predetermined intermediate opening is set according to the combustion state or the air-fuel ratio.

According to a fifth aspect of the present invention, in the first aspect, the fuel injection valve is provided in a cylinder head, and the injection hole of the fuel injection valve is opened to face a combustion chamber. Forms a concave flank formed of a predetermined curved surface for guiding the swirl flow while avoiding the adhesion of fuel spray.

In a sixth aspect based on the first aspect, the fuel injection valve injects fuel toward an upstream of the swirl from the spark plug.

In a seventh aspect based on the first aspect, the fuel injection valve is arranged so as to be offset upstream of the swirl from the spark plug.

In an eighth aspect based on the first aspect, the fuel injection valve is disposed along a center line of the cylinder, and the spark plug is located downstream of the swirl from the center line. Placed in

[0017]

Therefore, in the first invention, a plurality of intake ports are respectively constituted by straight ports, and one of the swirl control valves provided in each intake port permits the passage of intake air even when the valve is closed. When the swirl control valve is closed, the swirl control valve provided with the flow path cross-sectional area reducing portion causes intake air to be swirled in the combustion chamber when the swirl control valve is closed. If the swirl is maintained in the recess provided on the top surface of the piston, and fuel is injected from the fuel injection valve toward the swirl in the later stage of the compression stroke, the fuel spray is stratified and the ignition plug is disposed by the spark plug arranged opposite to the recess. Ignition is performed, and ultra-lean combustion can be performed stably.
On the other hand, when the swirl control valve is opened, intake is performed from a plurality of intake ports consisting of straight ports.Therefore, a tumble flow is generated in the combustion chamber, and if fuel is injected during the intake stroke, for example, fuel near the stoichiometric air-fuel ratio Since the spray is homogenized by the tumble flow, the ignition can be reliably performed by the ignition plug.
The output can be greatly improved as compared with the case where one of the two independent suction ports is a helical port, and the same or similar to the MPI type internal combustion engine while eliminating the need for complicated mechanisms such as a variable valve timing system. Higher output can be easily generated, and the structure of the direct injection type spark ignition internal combustion engine can be simplified to greatly reduce the production cost, while ensuring both output and ultra-lean combustion. it can.

According to a second aspect of the present invention, when the swirl control valve is closed, air is taken in from the swirl control valve provided with the flow path cross-sectional area reducing portion to generate swirl in the combustion chamber. If the swirl is maintained in the concave portion provided on the top surface, and fuel is injected from the fuel injection valve in the latter half of the compression stroke, the swirl can smoothly stratify the fuel spray, and is arranged to face the concave portion peripheral side. The ignition plug makes it possible to reliably ignite, so that ultra-lean combustion can be performed stably and the stability during stratified combustion can be improved.

In the third invention, the fuel injection angle of the fuel injection valve is set to a predetermined value between 50 ° and 90 °.
Combustion stability can be ensured while reducing the amount of smoke generated during stratified combustion, and both drivability and exhaust performance can be achieved.

According to a fourth aspect of the present invention, the swirl control valve closes during stratified combustion to generate mainly swirl, while it opens during homogeneous combustion to mainly generate a tumble flow, and the swirl control valve generates a swirl flow. When transitioning to combustion or vice versa, a predetermined intermediate opening is set according to the combustion state or air-fuel ratio, so the swirl and tumble ratio can be set to the optimal value according to each combustion state As a result, it is possible to improve the exhaust performance by reducing the amount of generated smoke and the amount of HC emission while improving the output performance and fuel efficiency of the direct cylinder injection type internal combustion engine.

According to a fifth aspect of the present invention, the cylinder head, in which the injection hole of the fuel injection valve faces the combustion chamber, is formed with a predetermined curved surface for preventing the fuel spray from adhering and guiding the swirl flow. By forming a concave flank, the outer periphery of the fuel spray is prevented from adhering to the cylinder head side, and a part of the swirl flow in the combustion chamber is guided to the vicinity of the injection hole, so that the vicinity of the fuel injection valve is provided. In addition to improving the reliability and durability of the direct in-cylinder injection spark ignition internal combustion engine by preventing the generation of deposits, it is also possible to improve the exhaust performance by reducing the amount of smoke generation or HC emission. Become.

According to the sixth aspect of the present invention, the fuel injection valve injects fuel toward the upstream of the swirl from the spark plug, so that the injected fuel is stratified upstream of the swirl flow from the spark plug. This makes it possible to more reliably ignite the fuel spray, further improve the stability of ultra-lean combustion by stratified combustion, and reduce fuel directly injected into the spark plug. Therefore, the amount of fuel adhering to the spark plug is reduced, so that the cold startability of the internal combustion engine can be improved.

According to the seventh aspect of the present invention, since the fuel injection valve is arranged so as to be offset from the spark plug upstream of the swirl, the injected fuel is stratified upstream of the swirl flow from the spark plug. This makes it possible to more reliably ignite the fuel spray, improve the stability of ultra-lean combustion by stratified combustion, and further reduce the fuel directly injected into the spark plug, The amount of fuel adhering to the spark plug is reduced, so that the cold start of the internal combustion engine can be improved.

According to an eighth aspect of the present invention, the fuel injection valve is disposed along the center line of the cylinder, while the spark plug is disposed downstream of the swirl from the center line. By being stratified on the upstream side of the swirl flow from the spark plug, it is possible to more reliably ignite the fuel spray and improve the stability of ultra-lean combustion by stratified combustion. Since the amount of fuel directly injected into the ignition plug can be reduced, the amount of fuel adhering to the ignition plug can be reduced, and the startability of the internal combustion engine during cold operation can be improved.

[0025]

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

FIGS. 1 to 3 show a four-valve spark-ignition internal combustion engine having two intake valves and two exhaust valves. A pent roof type combustion chamber 6 defined by a piston 3 and a cylinder head 2 has: Two independent first intake ports 8 and second intake ports 9 branched from the intake manifold 7 are opened and opened and closed via intake valves 4A and 4B.

Exhaust ports 13, 13 which are opened and closed by exhaust valves 5A, 5B are opened in the cylinder head 2 facing the first and second intake ports 8, 9, and these are opened by the intake valves 4A, 4B and the exhaust valve. An ignition plug 15 is provided at the center of the inner circumference of the cylinder head 2 surrounded by 5A and 5B. Note that the ignition plug 15 is arranged on the center line C of the cylinder 1.

The two first and second intake ports 8, 9 branched independently from the intake manifold 7 are formed as straight ports, and as shown in FIG. And the second intake port 9 are separated at a predetermined interval.

In the middle of the first intake port 8 and the second intake port 9, first and second swirl control valves 10 and 11 connected via an opening / closing shaft 12 are provided. It is opened and closed synchronously.

When the second swirl control valve 11 disposed in the second intake port 9 is fully closed with the valve opening α = 0 °, as shown by the broken line in FIG.
When the valve is fully opened at a valve opening α = 90 ° shown at 11 ′ in FIG. 1, the second intake port 9 can communicate the intake manifold 7 with the combustion chamber 6.

As shown in FIG. 2, the first swirl control valve 10 disposed in the first intake port 8 has the intake manifold 7 and the combustion chamber 6 when the valve opening α = 0 ° is fully closed. Notch 10A (channel cross-sectional area reduction section) so as to reduce the channel cross-sectional area while allowing communication
Is formed, and the first swirl control valve 1
The shape of 0 is, for example, a semicircle. Therefore, when the valve is fully closed with the valve opening α = 0 °, the notch 10
The intake air passes through a predetermined flow passage cross-sectional area between the first intake port 8 and the first intake port 8.

When the valve opening α is fully opened at 90 °, the first intake port 8 allows the intake manifold 7 to communicate with the combustion chamber 6 without reducing the cross-sectional area of the flow passage.

The open / close shaft 12 is moved from the fully closed position (α = 0 °) to the fully open position (α) of the first and second swirl control valves 10 and 11 by an actuator (not shown).
= 90 °) so that it can be locked at any position.

Next, the piston pin 17 and the connecting rod 1
A piston 3 connected to a crankshaft (not shown) through a combustion chamber 6 has a spark plug 1 on a top surface 3A facing the combustion chamber 6.
5, a circular concave portion 30 is formed at a predetermined depth from a position immediately below the peripheral edge of the piston 3 toward the intake valves 4A and 4B, and a swirl flow is formed on the inner periphery of the concave portion 30 during stratified combustion described later. At the same time, the fuel spray is stratified and guided to the ignition plug 15.

As shown in FIG. 2, a fuel injection valve 14 is disposed between the first intake port 8 and the second intake port 9 along the center line C of the cylinder 1. The injection hole 14A side has an opening 20 formed in the cylinder head 2.
The injection hole 14 </ b> A is disposed at a predetermined position facing the combustion chamber 6.

The axis Jc of the fuel spray injected from the injection hole 14A by the fuel injection valve 14 is coaxial with the axis of the fuel injection valve 14. In FIG. 1, the axis Jc of the fuel spray is indicated by a recess 30 formed on the piston top surface 3A. 2 is set so as to intersect with the vicinity of the center, and in FIG. 2, the axis Jc of the fuel spray is set to be coaxial with the center line C of the cylinder 1. Therefore, as shown in FIG. 1, the fuel injection valve 14 is supported by the cylinder head 2 in a state of being inclined at a shallow angle along the first and second intake ports 8 and 9.

The fuel injection valve 14 injects fuel in a cone at a predetermined angle θ, and the fuel injection angle θ is set between 50 ° and 80 ° as described later.
The pressure of the supplied fuel is relatively low, for example, 5 MPa.
And so on.

A concave spray relief surface 21 having a predetermined curved surface is provided on the cylinder head 2 from the end of the opening 20 where the injection hole 14A faces the combustion chamber 6 toward the intake valves 4A and 4B. It is formed.

As shown in FIG. 3, the spray relief surface 21 prevents the outer periphery of the fuel spray from adhering to the cylinder head 2 side, and the gas flow 40 in the combustion chamber 6 (hereinafter referred to as a swirl flow 40). ) Is formed so as to guide a part 40 ′ of FIG.

The operation will be described next.

At the time of stratified charge combustion for reducing fuel consumption, the opening and closing shaft 12 is driven to the position where the valve opening α = 0 ° to close the first and second swirl control valves 10 and 11.

When the valve opening α = 0 °, the second swirl control valve 11 completely closes the second intake port 9, while the first swirl control valve 10 having the notch 10 A is connected to the first intake port 9. 8, the passage cross-sectional area is reduced, and the passage of the intake air is allowed between the notch 10A and the inner wall.

Therefore, in the intake stroke, intake is performed only from the first intake port 8 whose flow path cross-sectional area has been reduced, and as shown in FIG. A clockwise swirl flow 40 is generated, and in the subsequent compression stroke, the swirl flow 40 is maintained in the recess 30 formed in the top surface 3A of the piston 3.

During stratified charge combustion, fuel is injected from the fuel injection valve 14 toward the recess 30 in the latter stage of the compression stroke, for example, as shown in FIG. 1, and the fuel spray is stratified by the swirl flow 40 in the recess 30. Therefore, the ignition can be reliably performed by the ignition plug 15 disposed opposite to the concave portion 30, and the super-lean combustion in which the air-fuel ratio A / F exceeds 40 can be realized.

On the other hand, at the time of homogeneous combustion in which the engine torque is increased during acceleration or the like, the opening / closing shaft 12 is set to the valve opening α = 90.
° to open the first and second swirl control valves 10 and 11.

When the valve opening α is fully opened at 90 °, the first
And the second swirl control valves 10 and 11
And the second intake ports 8 and 9 are completely opened to allow the passage of intake air through these two independent intake ports 8 and 9.

Therefore, in the intake stroke, intake is evenly performed from the first and second intake ports 8 and 9 constituted by straight ports, and a tumble flow is generated in the combustion chamber 6.

During homogeneous combustion, fuel is injected from the fuel injection valve 14 during the intake stroke, and the fuel spray having the air-fuel ratio A / F near the stoichiometric air-fuel ratio is homogenized by the tumble flow generated in the combustion chamber 6. Therefore, the ignition can be reliably performed by the ignition plug 15, and the air-fuel ratio A / F near the stoichiometric air-fuel ratio can be obtained.
As a result, a larger engine torque can be generated as compared with the stratified charge combustion. In particular, when the throttle is fully opened, an output equal to or higher than that of the conventional MPI internal combustion engine can be easily obtained.

In the intake process during the homogeneous combustion, first and second intake ports 8 and 9 comprising two straight ports
, The output can be greatly improved as compared with a case where one of the two independent suction ports is a helical port as in the conventional example, and the output of the conventional example can be greatly improved. By eliminating the need for such a complicated mechanism as a variable valve timing system, the structure of the direct in-cylinder injection spark ignition internal combustion engine is simplified, and the production cost is greatly reduced. It is possible to achieve both output securing and ultra-lean combustion by stratified combustion.

Here, as an intermediate region between the stratified combustion and the homogeneous combustion, as shown in FIG. 4, stratified lean combustion having an air / fuel ratio A / F smaller than that of the stratified combustion (A / F） 30),
The air-fuel ratio A / F is larger than that of the homogeneous combustion (A / F ≒ 2
0) The homogeneous lean combustion is set. During the stratified lean combustion or the homogeneous lean combustion, the opening α of the first and second swirl control valves 10 and 11 is set to an intermediate opening of about 45 °.

That is, according to the experiment conducted by the present applicant, the relationship between the air-fuel ratio A / F or the combustion state and the swirl ratio S and the tumble ratio T is as shown in FIG. At the time of stratified combustion, stratification of fuel spray can be promoted by mainly using a swirl flow, and it is desirable to increase the swirl ratio S and decrease the tumble ratio T. Therefore, the first and second swirl control valves 10,
The valve 11 is closed to generate a strong swirl flow.

On the other hand, on the rich side where the air-fuel ratio A / F is near the stoichiometric air-fuel ratio (the small A / F side in the figure), the tumble flow is mainly used to homogenize the fuel spray injected during the intake stroke. It is desirable to increase the S tumble ratio T while reducing the swirl ratio. For this reason, the first and second swirl control valves 10 and 11 are opened to generate a strong tumble flow by the two straight ports.

In the intermediate region between the stratified combustion and the homogeneous combustion, both the swirl and the tumble contribute to the homogenization and stratification of the fuel spray, so that the opening degree α of the first and second swirl control valves 10 and 11 is set. The swirl flow and the tumble flow are both generated by setting the intermediate opening degree at about 45 °. At this valve opening α ≒ 45 °,
Two intake ports 8, 9 in which intake is performed from the first and second intake ports 8, 9 with an intake amount corresponding to the valve opening.
As a result, the tumble flow is generated in the combustion chamber 6 and the amount of intake air from the first intake port 8 on the side of the first swirl control valve 10 having the notch 10A is controlled by the second swirl control. Since the amount of intake air is larger than that of the second intake port 9 on the valve 11 side, a swirl flow is generated in the combustion chamber 6 due to the difference between the amounts of intake air of the first and second intake ports.

The first and second swirl control valves 10 and 11 are set to the above-mentioned intermediate opening to perform homogeneous combustion at an air-fuel ratio A / F of about 20. The above-described stratified lean region performs stratified combustion with a fuel ratio A / F of about 30.

In the stratified lean combustion region, the first fuel injection is performed in the intake stroke, and then the second fuel injection is performed in the second half of the compression stroke in the same manner as in the above-described stratified combustion, so that the air-fuel ratio A / Lean combustion around F ≒ 30 is stably performed, and in the homogeneous lean combustion region, fuel is injected at the air-fuel ratio on the lean combustion side during the intake stroke to perform combustion similar to the above-described homogeneous combustion.

As described above, when shifting from stratified combustion to homogeneous combustion or in the opposite direction, the first and second swirl control valves 10 and 11 are set to intermediate openings to achieve stratified lean combustion and homogeneous lean combustion. By switching from stratified combustion to homogeneous combustion while sequentially switching the combustion state, torque fluctuation when switching between stratified combustion and homogeneous combustion is suppressed, and normal combustion near ultra-stoichiometric to stoichiometric air-fuel ratio is suppressed. The first and second swirl control valves 10 and 11 provided in the two straight ports are provided with a cutout portion 10A only in the first swirl control valve 10, so that the first and second swirl control valves 10 and 11 are provided with the cutout portions 10A. The swirl / tumble ratio is controlled continuously and in a wide range by the opening degree α of the second swirl control valves 10 and 11. Bet is to become possible.

Although the intermediate opening of the first and second swirl control valves 10 and 11 is set to about 45 °, the intermediate opening is appropriately changed according to the operating conditions and the like. The intermediate opening of the first and second swirl control valves 10 and 11 for performing the homogeneous lean combustion and the stratified lean combustion is set to different values during the transition from the combustion to the homogeneous combustion and the transition from the homogeneous combustion to the stratified combustion. Or the transition of the combustion state or the air-fuel ratio A / F
The opening of the first and second swirl control valves 10 and 11 may be continuously controlled in accordance with the increase and decrease of the first and second swirl control valves 10 and 11.
By variably controlling the swirl control valves 10 and 11, the ratio of swirl and tumble can be set to an optimum value according to each combustion state, and the output performance and fuel efficiency of the direct cylinder injection type internal combustion engine can be set. It is possible to improve the exhaust performance by reducing the amount of generated smoke and the amount of HC emission while improving the performance.

Next, the fuel injection angle θ of the fuel injection valve 14 and
FIG. 6 shows the relationship between the combustion stability and the amount of smoke generated in the direct cylinder injection type internal combustion engine.

As described above, when fuel injection is performed using a relatively low-pressure pressurized fuel of about 5 MPa, in order to stably stratify combustion by atomizing and atomizing the fuel,
The inventor of the present application performed an experiment on the fuel injection angle θ of the fuel injector 14 at the time of the atmospheric pressure, the combustion stability (for example, the torque fluctuation amount), and the amount of smoke generation, and as a result, the results are shown in FIG.

That is, when the fuel injection angle θ is less than about 50 °, the amount of fuel adhering to the concave portion 30 formed on the piston top surface 3A increases, so that the amount of smoke generated increases and the empty space near the ignition plug 15 increases. The fuel ratio A / F also increases and the combustion stability deteriorates.

On the other hand, when the fuel injection angle θ exceeds about 90 °, although the amount of smoke generated decreases, the stratification cannot be performed smoothly because the fuel spray flows out of the concave portion 30, and the combustion stability deteriorates again. I will.

Therefore, by setting the fuel injection angle θ of the fuel injection valve 14 at the time of the atmospheric pressure between 50 ° and 90 °, it is possible to secure the combustion stability while reducing the amount of smoke generated during stratified combustion. This makes it possible to achieve both operability and exhaust performance.

Next, the cylinder head 2 provided with the injection hole 14A of the fuel injection valve 14 facing the combustion chamber 6 is provided.
The spray relief surface 21 will be described.

As described above, the swirl flow 40 is generated in the combustion chamber 6, and during stratified combustion, fuel spray is put on the swirl flow 40 for stratification, so that the entire injection hole 14A is exposed into the combustion chamber 6. However, in the case where the upper part of the injection hole 14A is buried in the cylinder head 2 as shown in FIG. 1, the swirl flow 40 as shown in FIG.
Need to be guided to the injection hole 14A, and a concave spray flank 21 capable of avoiding attachment of fuel spray must be provided.

That is, as shown in FIG.
If a recess 22 is provided in the cylinder head 2 that covers the upper portion of the swirl flow 40 only to prevent fuel spray from adhering, a deposit as shown by oblique lines in the figure will adhere to the inner periphery of the recess 22 on the upstream side of the swirl flow 40. .

On the other hand, the outer circumference of the fuel spray is applied to the cylinder head 2 covering the upper portion of the injection hole 14A.
The swirl flow 4 can be prevented by adhering to the side of the swirl flow 40 by guiding a part 40 ′ of the swirl flow 40 in the combustion chamber 6 to the vicinity of the injection hole 14A.
In addition to improving the reliability and durability of the direct in-cylinder injection spark ignition internal combustion engine by preventing the generation of deposits in the concave portion upstream of the exhaust gas, the amount of smoke generated or the amount of HC emission is reduced. Performance can also be improved.

FIGS. 8 and 9 show a second embodiment, in which the axis Jc of the fuel injection of the fuel injection valve 14 in the first embodiment is shifted from the axis C of the cylinder 1 by a predetermined angle x. It is deflected to the intake port 8 side and the ignition plug 15
At the compression top dead center 3 ′ of the piston 3,
The piston is inserted into the inner periphery of the recess 30 formed in the piston top surface 3A, and the other components are the same as those of the first embodiment.

First, when the piston 3 is at the compression top dead center 3 ', the electrode 15A of the spark plug 15 is inserted into the inner periphery of the concave portion 30 of the piston top surface 3A. Since the spark plug 15 is inserted into the swirl flow generated by the intake air from the stove 8, the ignition of the stratified fuel spray can be performed more reliably, and the stability of the ultra-lean combustion by the stratified combustion can be improved. It can be further improved.

By deflecting the fuel injection axis Jc of the fuel injection valve 14 toward the first intake port 8 for performing intake during stratified charge combustion, the injected fuel is located on the upstream side of the swirl flow from the spark plug 15. And the amount of fuel directly injected into the ignition plug 15 can be reduced, so that the amount of fuel adhering to the ignition plug 15 can be reduced and the cold startability of the internal combustion engine can be improved. It is.

FIG. 10 shows a third embodiment, in which the first
The axis Jc of fuel injection of the fuel injection valve 14 in the embodiment
Is offset from the axis C of the cylinder 1 by a predetermined amount L toward the first intake port 8, and the other configuration is the same as that of the first embodiment.

The axis Jc of the fuel injection of the fuel injection valve 14 is
By offsetting to the first intake port 8 side for performing intake during stratified charge combustion, fuel directly injected to the ignition plug 15 can be reduced, and the fuel spray injected from the fuel injection valve 14 is swirled more than the ignition plug 15. The stratification is performed upstream of the flow, and the fuel adhering to the ignition plug 15 is reduced, so that the cold startability of the internal combustion engine can be improved. Note that the offset amount L is set to a predetermined value so that the injected fuel spray does not leak from the recess 30 of the piston 3.

FIG. 11 shows a fourth embodiment, in which the third embodiment is used.
In this embodiment, the offset amount L in the embodiment is applied to the ignition plug 15, and the ignition plug 15 is offset from the axis of the cylinder 1 toward the second intake port 9 by a predetermined amount L. The offset amount L is set to a predetermined value at which the spark plug 15 can face the inner periphery of the concave portion 30.

By offsetting the spark plug 15 to the side of the second intake port 9 where intake is stopped during stratified combustion, fuel directly injected into the spark plug 15 can be reduced, and the fuel spray injected from the fuel injection valve 14 can be reduced. Are stratified upstream of the swirl flow from the spark plug 15 and
Thus, the amount of fuel adhering to the internal combustion engine 5 is reduced, and the startability of the internal combustion engine in a cold state can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a direct cylinder injection type spark ignition internal combustion engine showing one embodiment of the present invention.

FIG. 2 is a view taken along the line AA of FIG. 1;

FIG. 3 is a front view of the spray relief surface.

FIG. 4 is a graph showing a relationship between a combustion state and a swirl control valve opening α according to engine torque and engine speed.

FIG. 5 is a graph showing a swirl or tumble generation state according to a combustion state.

FIG. 6 is a graph showing the relationship between the fuel injection angle θ at atmospheric pressure and the combustion stability or the state of smoke generation.

FIG. 7 is a front view of an opening in which a fuel injection valve is housed, showing a case where a spray relief surface is not provided.

FIG. 8 is a cross-sectional view of a direct cylinder injection type spark ignition internal combustion engine showing a second embodiment.

FIG. 9 is a view taken along the line BB of FIG. 8;

FIG. 10 is a sectional view of the cylinder head as viewed from the cylinder side, showing the third embodiment.

FIG. 11 is a sectional view of the cylinder head as viewed from the cylinder side, according to the fourth embodiment; Sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Cylinder head 3 Piston 3A Top surface 4A, 4B Intake valve 5A, 5B Exhaust valve 6 Combustion chamber 7 Intake manifold 8 First intake port 9 Second intake port 10 First swirl control valve 11 Second swirl control valve 10A Off Notch 12 Opening / closing shaft 14 Fuel injection valve 14A Injection hole 15 Spark plug 21 Spray relief surface 30 Concave portion

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 69/00 360 F02M 69/00 360C

Claims (8)

[Claims] 1. A fuel injection valve disposed facing a combustion chamber, a plurality of independent intake ports communicable with the combustion chamber via an intake valve, and a plurality of independent intake ports disposed in the intake port. A direct in-cylinder injection spark ignition internal combustion engine including a swirl generating means for generating a swirl, a concave portion formed on the piston top surface, and an ignition plug disposed at a position facing the concave portion; Each of the intake ports is constituted by a straight port, and the swirl generating means is constituted by a swirl control valve provided at each intake port and capable of being opened and closed synchronously. One of these swirl control valves is closed. A direct in-cylinder injection spark ignition internal combustion engine characterized by having a flow passage cross-sectional area reduction portion that allows passage of intake air even when a valve is provided. 2. The recess is formed so as to face an intake valve, and the ignition plug is disposed at a position that can face the inner peripheral side of the recess, and the fuel injection valve is directed toward the recess. 2. The direct in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the fuel is injected by a direct injection. 3. The direct cylinder according to claim 2, wherein the fuel injection valve injects the fuel in a conical shape and sets a fuel injection angle to a predetermined value between 50 ° and 90 °. Internal injection spark ignition internal combustion engine. 4. The swirl control valve closes during stratified combustion, opens when homogeneous combustion is performed, and when shifting from stratified combustion to homogeneous combustion, or vice versa, a predetermined value corresponding to the combustion state or air-fuel ratio. 2. The direct in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the opening degree is set to an intermediate opening. 5. The fuel injection valve according to claim 1, wherein the fuel injection valve is disposed on a cylinder head, and prevents fuel spray from adhering to the cylinder head, in which an injection hole of the fuel injection valve is opened facing a combustion chamber, and a swirl flow. The direct in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein a concave flank formed by a predetermined curved surface that guides the air flow is formed. 6. The direct in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the fuel injection valve injects fuel toward an upstream of the swirl from an ignition plug. 7. The direct in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the fuel injection valve is arranged to be offset upstream of the swirl from the spark plug. 8. The fuel injection valve according to claim 1, wherein the fuel injection valve is disposed along a center line of the cylinder, and the spark plug is disposed downstream of the swirl from the center line.
4. A direct in-cylinder injection spark ignition internal combustion engine according to claim 1.