JP2000199440A - Cylinder injection type spark ignition internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of NOX produced by a large margin and, at the same time, improve ignition performance and initial combustion by making a large amount of exhaust gases recirculate during stratified charge combustion. SOLUTION: This internal combustion engine is provided with exhaust valve opening means that opens an exhaust valve at a timing after a mid-point during an intake stroke to introduce part of recirculating exhaust gases required into a cylinder during stratified charge combustion. This engine also comprises a variable valve train means that either advances a valve opening timing of an intake valve or retards a valve closing timing of the exhaust valve, or does both, to allow the remaining part of recirculating exhaust gases required into the cylinder during stratified charge combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection spark ignition internal combustion engine.

[0002]

2. Description of the Related Art An in-cylinder injection spark ignition internal combustion engine having a fuel injection valve for directly injecting fuel into a cylinder, injects fuel at the end of a compression stroke and vaporizes the fuel by utilizing the heat of a piston or the like. The fuel is concentrated in the vicinity of the spark plug, and at the time of ignition, a flammable mixture having good ignitability is formed in the vicinity of the ignition plug, thereby achieving low fuel consumption stratified combustion that enables combustion of a lean mixture as a whole in the cylinder. It is intended to be implemented. However, the fuel injection amount at the end of the compression stroke that can form a combustible air-fuel mixture is not so large. In general, stratified combustion is limited to low engine load, and high engine load requires a relatively large amount of fuel. At times, uniform combustion is performed by fuel injection during the intake stroke.

In stratified combustion, in order to improve ignitability and initial combustion, a part of the exhaust gas is recirculated into the cylinder, and the intake gas in the cylinder is heated by the heat of the exhaust gas to form a portion near the ignition plug. It is desirable to increase the temperature of the combustible mixture to be produced. Exhaust gas recirculation, at the same time,
Lowering the combustion temperature by the large heat capacity of the inert gas is a main component of the exhaust gas to reduce the NO _x generation amount effect has. Since such recirculation of exhaust gas involves a decrease in output, it is preferable to recirculate a large amount of exhaust gas only in the case of stratified combustion that does not require high engine output.

A general exhaust gas recirculation apparatus has a communication passage for communicating an engine exhaust system and an engine intake system. Exhaust gas introduced into a cylinder thereby passes through the communication passage. During the stratified charge combustion, the intake air in the cylinder cannot be sufficiently heated. Also, an exhaust gas recirculation method in which the opening timing of the intake valve is advanced from the top dead center of the exhaust gas, a part of the exhaust gas flows backward to the intake port, and this exhaust gas is introduced into the cylinder in the intake stroke, Since the exhaust gas is cooled by the intake port having a relatively low temperature, it is not possible to sufficiently heat the intake air in the cylinder during stratified charge combustion.

Japanese Utility Model Laid-Open Publication No. 1-136666 discloses that an exhaust valve is opened in the latter half of the intake stroke in addition to the exhaust stroke by using two cams.
In the latter half of the intake stroke, high-temperature exhaust gas can be directly introduced into the cylinder from the exhaust port, and the intake air in the cylinder can be sufficiently heated during stratified charge combustion.

[0006]

However [0007], by the aforementioned prior art, with the intention of significant reduction of the NO _x generation amount with improved ignitability and initial combustion in the stratified combustion, a large amount of exhaust gas in the second half the intake stroke Is recirculated,
This large amount of exhaust gas is located in the upper part of the cylinder and does not sufficiently disperse in a short time in the subsequent compression stroke alone. In addition to improving ignitability and stratified combustion during stratified charge combustion, on the contrary, vaporized fuel near the spark plug Does not burn due to lack of oxygen,
Misfires can occur.

Accordingly, it is an object of the present invention, at the time of stratified charge combustion, NO _x by recirculating a large amount of exhaust gas
It is an object of the present invention to provide an in-cylinder injection type spark ignition internal combustion engine capable of significantly reducing the generation amount and improving ignitability and initial combustion.

[0008]

According to a first aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine for introducing a required amount of recirculated exhaust gas into a cylinder during stratified combustion. Exhaust valve opening means for opening the exhaust valve after the middle stage of the intake stroke; and, in order to introduce the remaining portion of the required amount of recirculated exhaust gas into the cylinder at the time of stratified combustion, the opening timing of the intake valve is determined. A variable valve means for performing at least one of an advance angle and a retard of the closing timing of the exhaust valve.

According to a second aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine having a first exhaust valve and a second exhaust valve, and a required amount of recirculated exhaust gas during stratified combustion. First exhaust valve opening means for opening the first exhaust valve after the middle stage of the intake stroke to introduce a part into the cylinder, and the remaining portion of the required amount of recirculated exhaust gas during stratified combustion. A second exhaust valve opening means for opening the second exhaust valve after the middle stage of the intake stroke for introduction into the cylinder; anda second exhaust valve opening means for the first exhaust valve by the first exhaust valve opening means. The valve opening start timing is characterized by being advanced from the valve opening start timing of the second exhaust valve by the second exhaust valve opening means.

According to a third aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the second aspect, wherein the required amount of the recirculated exhaust gas is provided. In order to make the part and the remaining part of the required amount of recirculated exhaust gas substantially equal, the opening period of the first exhaust valve by the first exhaust valve opening means is performed by opening the second exhaust valve. The opening period of the second exhaust valve by means is shortened.

According to a fourth aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the second aspect, wherein the required amount of the recirculated exhaust gas is reduced. In order to make the part and the remaining part of the required amount of recirculated exhaust gas substantially equal, the lift amount of the first exhaust valve by the first exhaust valve opening means is equal to the second exhaust valve opening means. The lift amount of the second exhaust valve is smaller than the lift amount of the second exhaust valve.

According to a fifth aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine, in which the exhaust valve is operated after the middle stage of the intake stroke in order to introduce a required amount of recirculated exhaust gas into the cylinder during stratified combustion. Exhaust valve opening means for opening the exhaust valve, and a guide wall for guiding the recirculated exhaust gas to be introduced toward an intake port is formed near an exhaust passage opening opened by the exhaust valve. Features.

According to a sixth aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine, in which the exhaust valve is operated after the middle stage of the intake stroke in order to introduce a required amount of recirculated exhaust gas into the cylinder during stratified combustion. Exhaust valve opening means for opening the exhaust valve, and a control valve disposed in an exhaust passage opened by the exhaust valve, while the exhaust valve is opened by the exhaust valve opening means. , Characterized in that the opening degree of the control valve is rapidly increased.

[0014]

FIG. 1 is a schematic longitudinal sectional view showing a first embodiment of a direct injection type spark ignition internal combustion engine according to the present invention. In the figure, 1 is an intake port, and 2 is an exhaust port. The intake port 1 communicates through the intake valve 3 and the exhaust port 2 communicates through the exhaust valve 4 into the cylinder.
Reference numeral 5 denotes a piston having a concave cavity 5 on its top surface.
a is formed. Reference numeral 6 denotes a spark plug disposed substantially at the center of the upper portion of the combustion chamber, and reference numeral 7 denotes a fuel injection valve for directly injecting fuel from the periphery of the cylinder into the cylinder. The internal combustion engine of the present embodiment is a four-valve type having two intake valves and two exhaust valves for each cylinder, and the fuel injection valve 7 uses an intake air flow in a combustion chamber to prevent fuel vapor. It is arranged between two intake valves which have a relatively low temperature.

The fuel injection valve 7 has a slit-shaped injection hole, and injects the fuel in a thin fan shape.
At a low engine load with a relatively small fuel injection amount, fuel is injected into the cavity 5a formed on the top surface of the piston 5 at the end of the compression stroke to perform stratified combustion, as shown in FIG. Although the fuel immediately after the injection indicated by the oblique lines is in a liquid state, it proceeds along the bottom surface of the cavity 5a and is vaporized by the side surface until it is guided to the vicinity of the ignition plug 6, and at the time of ignition, has good ignitability indicated by the one-dot chain line. It becomes a combustible mixture. Thus, by forming the combustible mixture only in the vicinity of the ignition plug 6, stratified charge combustion capable of burning a lean mixture as a whole in the cylinder can be realized.

Since the fan-shaped fuel spray having a small thickness spreads in the width direction when traveling along the bottom surface of the cavity 5a, heat can be favorably absorbed from a wide range of the bottom surface of the cavity 5a. In the fuel that has spread in the width direction on the bottom surface of the cavity 5a, an upward velocity component is given to the central portion of the fuel by the side surface of the cavity 5a, and the fuel goes toward the vicinity of the ignition plug 6, and both side portions of the fuel are the piston plane of the cavity 5a. When they collide with the arc-shaped side surfaces at an acute angle, a velocity component directed upward and a velocity component directed toward the center are also supplied, and the collision proceeds toward the vicinity of the ignition plug 6. In this manner, the fan-shaped fuel spray having a small thickness can form a flammable mixture having a good degree of vaporization in the vicinity of the ignition plug 6 as compared with the conventional conical fuel spray. As a result, it is possible to increase the amount of fuel during stratified combustion, and it is possible to expand stratified combustion with a low fuel consumption rate to a higher load side.

FIG. 3 shows a cam for opening and closing the exhaust valve 4 in this embodiment. The cam 10 has a first peak portion 10a for opening the exhaust valve 4 in the exhaust stroke,
Second peak 1 for opening exhaust valve 4 at the end of intake stroke
0b. As a result, at the end of the intake stroke,
A relatively large amount of exhaust gas is introduced into the cylinder from the two exhaust ports 2. The exhaust port 2 is maintained at a relatively high temperature because high-temperature exhaust gas passes therethrough periodically as compared with the intake port 1 through which low-temperature intake air passes. As a result, the temperature of the exhaust gas introduced into the cylinder is relatively high, so that the intake air can be sufficiently heated in the cylinder and the time until ignition is short.
At the time of ignition, the intake air is maintained at a sufficiently high temperature.

The main component of the exhaust gas is an inert gas, which has a large heat capacity. Thereby, a large amount of exhaust gas into the cylinder is introduced, sufficiently reduces the combustion temperature, it is possible to significantly reduce the NO _x emissions.

However, when a large amount of exhaust gas is simultaneously introduced from the two exhaust ports at the end of the intake stroke, the pressure in the cylinder is close to the atmospheric pressure at the end of the intake stroke. Exhaust gas flows only at a low speed together with the intake air from the intake port 1, resulting in four air flows of the exhaust gas and the intake air, but these four air flows are balanced with each other and do not cause sufficient agitation. Immediately after the inflow, this large amount of exhaust gas accumulates particularly in the upper part of the cylinder on the exhaust port side, and in the subsequent compression stroke, not only does it not sufficiently disperse by a short time until ignition,
Since the temperature of the exhaust gas is higher than that of the intake air, the exhaust gas tends to occupy the entire upper part of the cylinder. As a result, the fuel concentrated in the vicinity of the spark plug is in a very good vaporized state due to the high temperature in the cylinder, but the exhaust gas occupies the vicinity of the spark plug and may not ignite and burn due to lack of oxygen. High in nature. This problem occurs more remarkably when there is only one intake port and one exhaust port, because the agitation of the intake gas and the exhaust gas is more difficult to occur.

In the present embodiment, as shown in FIG. 2 which is a bottom view of the cylinder head and FIG. 1 described above, the exhaust gas flowing from the exhaust port 2 is close to the opening of the exhaust port 2 on the exhaust port side. A guide wall 8 for guiding exhaust gas to the intake port side is formed in order to prevent accumulation in the upper part of the cylinder. Thereby, the exhaust gas flow introduced into the cylinder in the latter half of the intake stroke collides with the intake flow introduced at the same time, and is easily stirred, and in the subsequent compression stroke, the exhaust gas and the intake air are sufficiently stirred. . As a result, during stratified combustion, the temperature of the combustible mixture formed in the vicinity of the ignition plug 6 is sufficiently increased without oxygen shortage, and the ignitability and the initial combustion are improved while the NO _x generation amount is greatly reduced. can do. Of course, by forming such a guide wall 8, even in a two-valve direct injection spark ignition internal combustion engine having one intake port and one exhaust port, sufficient agitation of intake air and exhaust gas at the end of the intake stroke is achieved. Is realized, and a similar effect can be obtained.

Even if such a guide wall 8 is not formed, if the amount of exhaust gas introduced into the cylinder at the end of the intake stroke is small, the exhaust gas will not occupy the vicinity of the spark plug at the time of ignition. It is possible to improve the ignitability and the initial combustion during stratified combustion to some extent as compared with the related art. However, so that the Simply reducing the amount of exhaust gas to be introduced into the cylinder in the intake stroke end, it is impossible to sufficiently reduce the NO _x emissions.

[0022] In the second embodiment of the present invention, as shown by the solid line in FIG. 4, the second convex portion 10b of the cam 10 decreases and low for the exhaust valve 4, sufficiently reduce the NO _x generation amount Only a fraction of the amount of recirculated exhaust required to
In addition to being introduced into the cylinder late in the intake stroke,
The opening timing of the intake valve 3 is set to be significantly advanced from the intake top dead center (TDC), and the remaining part of the required amount of recirculated exhaust gas is covered by the exhaust gas that has flowed back to the intake port 1 at the end of the exhaust stroke. Like that. Alternatively, instead of or in addition to the advance of the opening timing of the intake valve 3, the closing timing of the exhaust valve 4 may be retarded from the intake top dead center. From 2, exhaust gas is introduced into the cylinder.

In the direct injection spark ignition internal combustion engine, the fuel injection amount at the end of the compression stroke at which a combustible mixture can be formed is:
Even when a fan-shaped fuel spray having a small thickness is used, the fuel spray is not so large, and at the time of a high engine load requiring a relatively large amount of fuel, uniform combustion is performed by fuel injection in an intake stroke. Recirculation of a large amount of exhaust gas is effective in reducing the amount of NO _x generated, but the engine output tends to decrease,
In high-load, uniform engine combustion requiring high output, it is preferable to reduce the amount of exhaust gas to be recirculated. Thereby, in the present embodiment, if the opening timing of the intake valve can be changed by using the variable valve timing mechanism, as shown by the dotted line in FIG. The timing is set to be near the intake top dead center, and at the time of stratified combustion, the valve opening timing of the intake valve 3 can be made to be significantly advanced from the intake top dead center, so that a large amount of exhaust gas recirculation at the time of stratified combustion, A small amount of exhaust gas recirculation during uniform combustion can be realized. When changing the closing timing of the exhaust valve, if an actuator that freely opens and closes the exhaust valve by an electromagnetic or hydraulic system is used as the exhaust valve operating mechanism, only the closing timing of the exhaust valve in the early stage of the intake stroke is required. Can be changed, and a small amount of exhaust gas recirculation during uniform combustion can be realized.

FIG. 5 shows a valve opening pattern of the exhaust valve according to the third embodiment of the present invention. FIG. 4A shows the opening pattern of one of the exhaust valves 4. As described above, the exhaust valve 4 is opened at the end of the intake stroke in addition to the exhaust stroke. FIG. 4B shows a valve opening pattern of the other exhaust valve 4. The exhaust valve 4 is opened in the middle of the intake stroke in addition to the exhaust stroke. Thus,
With one of the exhaust gas to the intake stroke end via an exhaust valve 4 is introduced into the cylinder, the exhaust gas to the intake stroke metaphase through the other exhaust valve 4 is introduced into the cylinder, the NO _x generation amount sufficient The amount of recirculated exhaust gas necessary to reduce the amount of exhaust gas is introduced into the cylinder. The cam for the other exhaust valve 4 has a second peak portion as compared to the same cam 10 for one exhaust valve 4 shown in FIG. 3 for opening the exhaust valve 4 in the middle of the intake stroke. Is located near the first mountain.
Since the pressure in the cylinder in the middle stage of the intake stroke is lower than that at the end of the intake stroke, the exhaust gas flow introduced in the middle stage of the intake stroke is relatively high. As a result, this exhaust gas flow collides with the relatively high-speed intake air flow introduced at the same time, is sufficiently stirred, and is generated at the end of the subsequent intake stroke by this turbulence to generate turbulence in the cylinder. The same effect as described above can be obtained by stirring the exhaust gas flow.

In the present embodiment, the more the exhaust gas flow introduced into the cylinder in the middle stage of the intake stroke, the better the agitation between the exhaust gas and the intake gas including the exhaust gas introduced at the end of the subsequent intake stroke. However, on the other hand, since a large amount of exhaust gas is recirculated early, the temperature of the intake air heated by the exhaust gas tends to decrease by the time of ignition, and the degree of increasing the temperature of the combustible mixture increases. descend.
Therefore, by making the amount of exhaust gas introduced into the cylinder in the middle stage of the intake stroke substantially equal to the amount of exhaust gas introduced into the cylinder at the end of the intake stroke, sufficient agitation of the exhaust gas with the intake air and the flammable mixture It is possible to simultaneously raise the temperature sufficiently.

In the present embodiment, the second peak of the cam for opening the other exhaust valve in the middle of the intake stroke is the second peak of the cam for opening the one exhaust valve at the end of the intake stroke. The width is narrowed and the height is reduced as compared with. Thereby, as shown in FIG. 5, the opening period of the other exhaust valve in the middle stage of the intake stroke is shorter than the opening period of the one exhaust valve in the end stage of the intake stroke,
The lift amount of the other exhaust valve in the middle stage of the intake stroke is
The lift amount is smaller than the lift amount of one of the exhaust valves at the end of the intake stroke. Thus, since the pressure in the cylinder in the middle of the intake stroke is lower than the pressure in the cylinder at the end of the intake stroke, the exhaust gas is easily introduced, but the exhaust gas introduced into the cylinder in the middle of the intake stroke The amount and the amount of exhaust gas introduced into the cylinder at the end of the intake stroke can be made substantially equal. Of course, the second peaks of these two cams are also different in only one of the width and the height, so that the amount of exhaust gas introduced into the cylinder in the middle of the intake stroke and the amount of exhaust gas introduced into the cylinder at the end of the intake stroke And the exhaust gas amount can be made substantially equal.

FIG. 5 is a schematic longitudinal sectional view of a direct injection type spark ignition internal combustion engine showing a fourth embodiment of the present invention. Only the differences from the first embodiment will be described below. In the present embodiment, a control valve 21 is disposed in an exhaust pipe 20 connected to the exhaust port 2 instead of providing a guide wall. The exhaust valve 4 is similar to the first embodiment,
The valve is opened at the end of the intake stroke in addition to the exhaust stroke. Control valve 2
FIG. 7 shows the relationship between the opening / closing control 1 and the opening of the exhaust valve 4.
The control valve 21 is fully opened at least during the exhaust stroke to prevent an increase in exhaust resistance. However, the control valve 21 is fully closed before the exhaust valve 4 starts to open at the end of the intake stroke, and the exhaust valve 4 at the end of the intake stroke. Is fully opened when the lift amount has increased to some extent.

As a result, exhaust gas is rapidly introduced into the cylinder at the same time when the control valve 21 is fully opened.
The flow rate of the introduced exhaust gas flow becomes relatively high, sufficient stirring with the intake air flow can be realized, and the same effect as described above can be obtained. Further, during uniform combustion, if the opening of the control valve 21 at the time of opening the exhaust valve 4 at the end of the intake stroke is reduced, the amount of exhaust gas recirculated into the cylinder can be reduced, and stratified combustion can be achieved. A large amount of exhaust gas recirculation at the time and a small amount of exhaust gas recirculation during uniform combustion can be realized.

[0029]

As described above, according to the in-cylinder injection spark ignition internal combustion engine according to the first aspect of the present invention, the exhaust valve opening means is configured to reduce the required amount of recirculated exhaust gas during stratified combustion. The exhaust valve is opened after the middle stage of the intake stroke in order to introduce the gas into the cylinder, and the variable moving means operates the intake valve to introduce the required amount of recirculated exhaust gas into the cylinder during stratified combustion. to implement at least one of the closing timing of the advance angle and the exhaust valve opening timing retarded, significant reduction of the NO _x generation amount becomes possible recirculation of a large amount of exhaust gas during stratified charge combustion Becomes possible. Furthermore, the high-temperature exhaust gas introduced into the cylinder via the exhaust valve after the middle stage of the intake stroke makes it possible to sufficiently raise the temperature of the combustible air-fuel mixture during stratified combustion, and this exhaust gas amount is not so large. Since there is not much, it is not sufficiently dispersed and unevenly distributed in the vicinity of the spark plug by the time of ignition, and the ignitability and the initial combustion during stratified combustion can be improved.

According to a second aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine including a first exhaust valve and a second exhaust valve, wherein the first exhaust valve opening means includes a stratified valve. The first exhaust valve is opened after the middle stage of the intake stroke in order to introduce a part of the required amount of recirculated exhaust gas into the cylinder at the time of combustion, and the second exhaust valve opening means performs the required amount at the time of stratified combustion. The second exhaust valve is opened after the middle stage of the intake stroke in order to introduce the remaining part of the recirculated exhaust gas into the cylinder, so that a large amount of exhaust gas can be recirculated during stratified combustion and NO
_The amount of _x generation can be greatly reduced. Furthermore, since the opening timing of the first exhaust valve by the first exhaust valve opening means is set to be more advanced than the opening timing of the second exhaust valve by the second exhaust valve opening means, The flow rate of the exhaust gas stream introduced through one exhaust valve becomes relatively high, and is sufficiently stirred by the collision with the relatively high-speed intake air introduced at the same time to generate turbulence. The exhaust gas stream introduced through the two exhaust valves can be agitated. This makes it possible to sufficiently increase the temperature of the combustible air-fuel mixture during stratified combustion with the high-temperature exhaust gas introduced into the cylinder via the exhaust valve after the middle stage of the intake stroke, and this exhaust gas The ignitability and the initial combustion during stratified combustion can be improved without being sufficiently dispersed and unevenly distributed in the vicinity of the spark plug by the time of ignition.

According to a third aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the second aspect, wherein the first exhaust valve opening means is provided. The opening period of the first exhaust valve is made shorter than the opening period of the second exhaust valve by the second exhaust valve opening means. A portion of the circulating exhaust gas is substantially equal to the remainder of the required amount of recirculated exhaust gas. Exhaust gas introduced via the first exhaust valve is more advantageous for agitating the exhaust gas and the intake air than exhaust gas introduced via the second exhaust valve, while flammable mixing Since it is disadvantageous to increase the temperature of the gas, it is possible to achieve both the stirring of the exhaust gas and the intake air and the increase of the temperature of the combustible air-fuel mixture by making the exhaust gas amounts substantially equal.

According to a fourth aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the second aspect, wherein the first exhaust valve opening means is provided. Since the lift amount of the first exhaust valve is made smaller than the lift amount of the second exhaust valve by the second exhaust valve opening means, the required amount of recirculated exhaust gas depends on the pressure in the cylinder when exhaust gas is introduced. A portion of the gas is substantially equal to the remainder of the required amount of recirculated exhaust gas. Thereby, the same effect as that of the in-cylinder injection spark ignition internal combustion engine according to the third aspect can be obtained.

According to the in-cylinder injection spark ignition internal combustion engine according to claim 5 of the present invention, the exhaust valve opening means comprises:
The exhaust valve is opened after the middle stage of the intake stroke to introduce a required amount of recirculated exhaust gas into the cylinder during stratified combustion, and is introduced near the exhaust passage opening opened by the exhaust valve. to guide wall for guiding the recirculated exhaust gas to the intake port side is formed, it is possible to greatly reduce of the NO _x generation amount becomes possible recirculation of a large amount of exhaust gas during stratified charge combustion. Furthermore, the temperature of the combustible air-fuel mixture during stratified combustion can be sufficiently increased by the high-temperature exhaust gas introduced into the cylinder via the exhaust valve after the middle stage of the intake stroke, and the flow rate of this exhaust gas flow is reduced. Even if it is relatively late, the guide wall forces the air to the intake port side, causing sufficient agitation due to collision with the intake air flow, and the exhaust gas is sufficiently dispersed and unevenly distributed near the ignition plug by the time of ignition However, ignitability during stratified combustion and initial combustion can be improved.

According to the in-cylinder injection spark ignition internal combustion engine of the present invention, the control valve is disposed in the exhaust passage opened by the exhaust valve, and the exhaust valve opening means comprises a stratified valve. During combustion, the exhaust valve is opened after the middle stage of the intake stroke in order to introduce the required amount of recirculated exhaust gas into the cylinder, and while the exhaust valve is opened by the exhaust valve opening means, the control valve is opened. to increase the degree of opening rapidly, it is possible to greatly reduce of the NO _x generation amount becomes possible recirculation of a large amount of exhaust gas during stratified charge combustion. Furthermore, the temperature of the combustible mixture during stratified combustion can be sufficiently increased by the high-temperature exhaust gas introduced into the cylinder through the exhaust valve after the middle stage of the intake stroke, and the flow rate of this exhaust gas flow is reduced. However, since the opening of the control valve can be relatively increased by a rapid increase, sufficient agitation occurs due to collision between the exhaust gas flow and the intake air. Ignitability during stratified combustion and initial combustion can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing a first embodiment of a direct injection type spark ignition internal combustion engine according to the present invention.

FIG. 2 is a bottom view of a cylinder head of the in-cylinder injection spark ignition internal combustion engine of FIG. 1;

3 is a view showing a cam for an exhaust valve used in the direct injection spark ignition internal combustion engine of FIG. 1. FIG.

FIG. 4 is a view showing a valve opening pattern of an exhaust valve and an intake valve showing a second embodiment of the direct injection type spark ignition internal combustion engine according to the present invention.

5A and 5B are diagrams showing a valve opening pattern of an exhaust valve showing a third embodiment of a direct injection type spark ignition internal combustion engine according to the present invention, wherein FIG. 5A shows one exhaust valve and FIG. It is a valve opening pattern of a valve.

FIG. 6 is a schematic longitudinal sectional view showing a fourth embodiment of the direct injection type spark ignition internal combustion engine according to the present invention.

7 is a diagram showing a relationship between a valve opening pattern of an in-cylinder injection type spark ignition internal combustion engine of FIG. 6 and an opening / closing control of a control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake port 2 ... Exhaust port 3 ... Intake valve 4 ... Exhaust valve 5 ... Piston 6 ... Spark plug 7 ... Fuel injection valve

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 9/04 F02D 9/04 Z 41/02 320 41/02 320 F02M 25/07 510 F02M 25/07 510B 580 580C ( 72) Inventor Takeshi Okumura 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Shigeo Furuno 1 Toyota Motor Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G023 AA05 AB01 AC04 AD02 AG01 AG03 3G062 AA07 AA10 BA09 3G065 AA06 AA09 CA12 3G092 AA01 AA06 AA09 AA11 DA01 DA02 DA08 DA12 DA14 DC09 DC12 EA01 EA02 EA03 EA04 FA17 FA21 3G301 HA01 HA04 HA09 HA16 HA19 NE04 NE12 NE07 LA07

Claims (6)

[Claims] 1. An exhaust valve opening means for opening an exhaust valve after a middle stage of an intake stroke in order to introduce a part of a required amount of recirculated exhaust gas into a cylinder during stratified combustion. Variable valve means for performing at least one of advancing the opening timing of the intake valve and retarding the closing timing of the exhaust valve to introduce the remaining portion of the required amount of recirculated exhaust gas into the cylinder; An in-cylinder injection spark ignition internal combustion engine characterized by comprising: 2. A fuel supply system comprising a first exhaust valve and a second exhaust valve, wherein the first exhaust valve is provided during an intake stroke in order to introduce a required amount of recirculated exhaust gas into a cylinder during stratified combustion. First exhaust valve opening means for opening after the middle stage, and the second exhaust valve after the middle stage of the intake stroke in order to introduce the remaining portion of the required amount of recirculated exhaust gas into the cylinder during stratified combustion. And a second exhaust valve opening means for opening the first exhaust valve by the first exhaust valve opening means, the second exhaust valve opening means for opening the second exhaust valve by the second exhaust valve opening means. An in-cylinder injection spark ignition internal combustion engine characterized in that it is advanced from the valve opening start timing. 3. The first exhaust valve opening means for opening the first portion of the required amount of recirculated exhaust gas substantially equal to the remaining portion of the required amount of recirculated exhaust gas. The in-cylinder injection spark ignition internal combustion engine according to claim 2, wherein an opening period of the exhaust valve is shorter than an opening period of the second exhaust valve by the second exhaust valve opening means. . 4. The method according to claim 1, wherein the first portion of the first exhaust valve is provided by the first exhaust valve opening means so that the portion of the required amount of recirculated exhaust gas is substantially equal to the remaining portion of the required amount of recirculated exhaust gas. 3. The direct injection spark ignition internal combustion engine according to claim 2, wherein a lift amount of the exhaust valve is smaller than a lift amount of the second exhaust valve by the second exhaust valve opening means. 5. An exhaust valve opening means for opening an exhaust valve after a middle stage of an intake stroke to introduce a required amount of recirculated exhaust gas into a cylinder during stratified combustion, and an exhaust valve opened by the exhaust valve. A guide wall for guiding the recirculated exhaust gas to be introduced toward the intake port is formed in the vicinity of the exhaust passage opening. 6. An exhaust valve opening means for opening an exhaust valve after a middle stage of an intake stroke to introduce a required amount of recirculated exhaust gas into a cylinder during stratified combustion, and an exhaust valve opened by the exhaust valve. A control valve disposed in the exhaust passage, wherein the opening of the control valve is rapidly increased while the exhaust valve is opened by the exhaust valve opening means. In-cylinder injection spark ignition internal combustion engine.