JP2004144052A - Theoretical air fuel ratio stratified charge combustion internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in fuel economy by a rich spike to obtain a high exhaust emission control effect, while reducing pumping loss by stratified charge combustion to improve fuel economy. <P>SOLUTION: An opening/closing timing for an intake valve is shifted by a variable mechanism and EGR gas is made to flow first into a cylinder. An air fuel ratio therefore is always kept in the vicinity of a theoretical air fuel ratio, while reducing the pumping loss by stratifying air-fuel mixture and EGR gas, and excellent combustion can be performed. Since a three-way catalyst can be used, a lean NOx catalyst becomes unnecessary, the deterioration in the fuel economy by the rich spike can be prevented, the cost can be reduced, and the large emission control effect can be obtained. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine that injects fuel directly into a cylinder and burns mainly by ignition.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known an internal combustion engine that directly injects fuel into a cylinder, in which EGR gas (exhaust gas recirculation gas) is introduced to reduce harmful components in exhaust gas. Further, at that time, there is known one in which the mixture ratio of the EGR gas is changed depending on the location in order to effectively maintain the combustion performance. As an example of these, for example, there is a system as described in Japanese Patent Application Laid-Open No. 2001-280140.
[0003]
This system mainly relates to a compression ignition engine, in which EGR gas passages each having a control valve are connected to two intake ports opened to one cylinder, and the shape of the intake port and the opening period of the intake valve are shifted. Thus, a layer with a large amount of EGR gas and a layer with a small amount of EGR gas are formed in the cylinder. Then, the intake air stratified in the longitudinal direction of the cylinder becomes stratified in the axial direction in the piston cavity by the squish flow in the compression stroke, and by injecting fuel there, the NOx and soot (black smoke) are effectively formed. It is said that simultaneous reduction can be achieved.
[0004]
[Patent Document 1]
JP 2001-280140 A (Pages 5-6, FIGS. 2, 4)
[0005]
[Problems to be solved by the invention]
However, the above configuration has the following problems.
[0006]
That is, the independent intake pipe used in the conventional configuration has a configuration suitable for generating swirl, but due to a bend provided in the intake pipe, the ventilation resistance at a high load is large. However, there is a problem that a sufficient amount of air cannot be sucked by the negative pressure generated when the piston descends, leading to a decrease in output. In addition, the shape of the piston has a cavity, so that the thickness of the piston is inevitably increased, that is, the weight is increased, and there is a problem that it becomes an obstacle when the engine speed is increased to improve the output. . Further, since the configuration is such that the EGR gas is introduced into each of the independent intake pipes, there is a problem that the piping and mechanism for that are complicated, leading to an increase in cost and weight.
[0007]
In addition, the compression ignition engine described in the conventional configuration, that is, the diesel engine, has the disadvantage that it is difficult to simultaneously reduce black smoke and NOx, and it is difficult to install a catalyst. Has become. In the case of a gasoline engine, when stratified combustion is performed using a lean mixture as a whole, the use of a conventional three-way catalyst for reducing emissions (exhaust gas) has no effect. In particular, NOx ( It is common to use a NOx reduction catalyst to purify nitrogen oxides. The method of using this catalyst is to enrich the air-fuel ratio to about 13 at regular intervals and to adsorb it during lean operation. It is necessary to perform an operation for reducing the NOx that has been performed. Although this is called a rich spike, not only stratified combustion cannot be performed during the rich spike, but also wasteful fuel is consumed as energy for NOx reduction. However, there is a problem that the actual fuel efficiency improvement rate becomes low because the fuel consumption is offset by the rich spike. At this time, in the present technology, the purification rate of NOx in the NOx reduction catalyst is about 90% at the maximum, which is lower than the purification rate of 99% when a three-way catalyst is used. Even so, there is a problem that the amount of NOx exhausted from the tail pipe, that is, the exhaust pipe is increased as a result.
[0008]
The present invention has been made in order to solve the above-mentioned problems, and it is possible to secure a sufficient amount of air at a high load by reducing the weight of a piston suitable for realizing a high rotation and reducing the resistance of an intake passage. A first object is to provide a system capable of performing stratified combustion while having a configuration. In addition, by effectively using a three-way catalyst with high exhaust purification efficiency, the deterioration of emissions is suppressed at low cost.Furthermore, rich spikes are not performed during stratified combustion or the number of times A second object is to provide a stratified combustion system that prevents deterioration.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following means.
[0010]
First, an internal combustion engine capable of directly injecting fuel into a cylinder is provided with an independent intake pipe divided into at least two parts and a swirl control valve capable of closing one of them. Furthermore, an EGR (Exhaust Gas Recirculation) valve for recirculating exhaust gas is provided, and the EGR passage is opened to a closed intake pipe portion. When the intake valve is opened, the gas flowing into the combustion chamber from one of the independent intake pipes is mainly air, and the gas flowing from the other of the independent intake pipes is mainly EGR gas.
[0011]
In addition, a variable valve timing mechanism is provided for making at least one intake valve open and close at a different phase from the other intake valves.
[0012]
The top surface of the piston is formed as a flat surface or an uneven surface provided with a valve recess to reduce the weight. Further, a three-way catalyst is provided in the exhaust passage.
[0013]
Further, in the in-cylinder direct fuel injection engine configured as described above, the fuel injection device is controlled such that fuel injection is performed during the latter half of the compression stroke during stratified charge combustion and during the intake stroke during homogeneous operation.
[0014]
With the above configuration, the present invention has the following operation.
[0015]
In a low engine load range, the swirl control valve is closed, and EGR gas from the EGR valve is allowed to flow into the closed independent intake pipe. Then, in the intake stroke, the intake valve on the side where the EGR gas is flowing is opened first, and only the EGR gas flows into the combustion chamber. Then, in the latter half of the intake stroke, the intake valve not closed by the swirl control valve is opened to allow combustion air to flow. By causing the EGR gas and the combustion air to flow into the combustion chamber with a time difference, the intake air and the EGR gas are kept separated. In the subsequent compression stroke, fuel is injected toward the intake air. At this time, the fuel injection amount is controlled so that the air-fuel ratio of the mixture becomes the stoichiometric air-fuel ratio. In this way, the exhausted EGR gas has the same composition as the exhaust gas burned at the stoichiometric air-fuel ratio. In this way, stratification of the air-fuel mixture is performed, and while improving fuel efficiency by reducing pumping loss and cooling loss, the air-fuel ratio of the entire gas is set to the stoichiometric air-fuel ratio that can be used by the three-way catalyst, and NOx and HC are simultaneously purified.
[0016]
Furthermore, when a higher load is required, the intake resistance is increased by opening the swirl control valve to increase the amount of intake air, and sufficient fuel is injected and vaporized by injecting fuel into the intake stroke. Ensure mixing time, perform homogeneous combustion, and secure required output.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 show the configuration of the first embodiment of the present invention as viewed from above in FIG. 1 and viewed from the horizontal direction in FIG. In this embodiment, a multi-cylinder engine is mainly assumed, but one cylinder is described in the figure for simplicity.
[0018]
A swirl control valve 102 is attached to the intake pipe 101 so that 101b of the two independent intake pipes 101a and 101b can be opened and closed.
[0019]
The injector 122 is mounted so as to inject fuel directly into the cylinder 123.
[0020]
The air sucked in from the right side of the figure passes through an air cleaner 106, measures the flow rate by an air flow meter 105, adjusts the flow rate by an electronic control throttle chamber 104, and is distributed to each cylinder by a collector 103. Thereafter, the gas flows through the above-described intake pipes 101a and 101b, and flows into the cylinder 123 when the intake valves 111a and 111b are opened.
[0021]
The gas burned in the cylinder passes through an exhaust valve 112 and an exhaust pipe 110, is purified by a three-way catalyst 115, and is exhausted to the atmosphere through a silencer (not shown). At this time, a part of the gas is recirculated to the intake pipe 101 using the EGR passage 109 while adjusting the flow rate by the EGR control valve 108. The EGR passage 109 is opened in the EGR-side independent intake pipe 101b.
[0022]
The fuel injection timing of the injector 122, the ignition timing of the ignition plug 113, the opening of each of the swirl control valve 102, the electronic control throttle chamber 104, and the EGR control valve 108 are determined by the amount of intake air measured by the air flow meter 105 and the accelerator opening. The computer 201 sets and controls optimal values and timings based on information such as degrees, engine water temperature, engine speed, and vehicle speed (all of which do not show sensors for inputting them).
[0023]
When performing stratified combustion, first, the swirl control valve 102 is closed to close the EGR-side independent intake pipe 101b, and EGR gas is flown into the EGR-side independent intake pipe 101b using the EGR passage 109 and the EGR control valve 108, and is filled. Keep it.
[0024]
The EGR side intake valve 111b is opened first in the latter half of the exhaust stroke of the engine or in the intake stroke. Due to the negative pressure generated by the piston 107, EGR gas flows in from the EGR-side independent intake pipe 101b, and fills the cylinder 123 while forming the swirl 121 clockwise as viewed from above in the drawing. It is desirable that the change amount of the lift start and end crank angles of the EGR-side intake valve 111b be equal to or more than 20 degrees CA (* CA is an abbreviation of the crank angle) so that the mixture of the EGR gas and the intake air is reduced as much as possible. In this way, in the conventional engine, in the latter half of the exhaust stroke, the exhaust valve 112 and the EGR-side intake valve 111b open simultaneously, that is, the so-called overlap period becomes longer, and the EGR gas and air are expected to be blown back to the intake pipe. However, in the present invention, the EGR-side independent intake pipe 101b is closed by the swirl control valve 102, and the EGR-side independent intake pipe 101b is blocked by the swirl control valve 102. Since the independent intake pipe 101b is originally filled with EGR gas, there is no problem even if the exhaust valve 112 is opened.
[0025]
Next, when the intake valve 111a is opened in the latter half of the intake stroke, air flows into the cylinder 123 through the independent intake pipe 101a and the intake valve 111a, and forms a swirl 120 counterclockwise as viewed from above in the drawing. . Although the swirls 120 and 121 flow in opposite directions, the opening phases of the intake valves 111a and 111b are different, so that the swirl 120 of the EGR gas is below the cylinder 123 and the swirl 121 of the intake air is above the cylinder 123. In the short period between the intake stroke and the compression stroke of the engine, the mixture can be present in a stratified state without mixing.
[0026]
Subsequently, in the compression stroke, the intake valves 111a and 111b close, the piston 107 rises, and the air in the cylinder 123 is compressed. Here, fuel is injected from the injector 122. At this time, as shown in FIG. 2, the spray pressure is adjusted by adjusting the fuel pressure or the like so that the spray 125 faces the swirl 121 of the intake air and does not collide with the cylinder wall or the combustion chamber wall. Set optimally. Further, here, the fuel spray 125 is a so-called deflected spray in which a component going upward in the figure is larger than a component going downward. With this configuration, the swirl 121 and the spray 125 are efficiently mixed. Further, the mixture ratio of the intake air and the fuel, that is, the air-fuel ratio is adjusted to be close to the stoichiometric air-fuel ratio at which the three-way catalyst 115 can efficiently purify the exhaust gas. In the latter half of the compression stroke, that is, when the optimal ignition timing is reached, the ignition plug 113 is ignited by a signal from the computer 201 to cause combustion.
[0027]
In this way, while forming a mixture having a stoichiometric air-fuel ratio that enables good combustion in the vicinity of the ignition plug, the overall intake amount is increased, and pumping loss and cooling loss are reduced, thereby improving fuel efficiency. Since the engine is not operated with a lean air-fuel mixture as in the prior art, there is no need to use a lean NOx catalyst, and there are no problems such as deterioration of fuel efficiency due to rich spikes or a low NOx removal rate and a small exhaust gas purification effect. Further, since it is not necessary to use both the lean NOx catalyst and the three-way catalyst, the cost can be reduced.
[0028]
FIG. 3 shows a lift curve of the intake / exhaust valve according to the first embodiment of the present invention. The operation of the EGR-side intake valve 111b is advanced only during stratified combustion without changing the operation of the intake valve 111a and the two exhaust valves 112. It is desirable that the amount of change in the lift start and end crank angles be equal to or greater than 20 degrees CA (* CA is abbreviation of crank angle) so that the mixture of EGR gas and intake air is reduced as much as possible. By doing so, the exhaust valve 112 and the EGR-side intake valve 111b are simultaneously opened in the latter half of the exhaust stroke, that is, the so-called overlap period becomes longer, but the inside of the independent intake pipe 101b is closed and filled with EGR gas. Also, there is no problem such as exhaust gas blowing back. When the intake valve 111a reaches the fully opened lift amount, the EGR-side intake valve 111b has begun to close, and the operation of the intake air as described with reference to FIGS. 1 and 2 can be obtained.
[0029]
4 and 5 show the operation of the first embodiment when the engine load is small.
[0030]
First, according to a signal from the computer 201, the electronically controlled throttle chamber
The opening of 104 is set small. On the other hand, the opening of the EGR control valve 108 is set large. As a result, when the intake valves 111a and 111b are opened during the intake stroke of the engine, the gas drawn into the cylinder 123 is more likely to flow through the EGR-side independent intake pipe 101b than the intake air flowing through the independent intake pipe 101a. The amount of gas is larger and the amount of swirl 120 is larger than swirl 121. Even in this case, the swirl 121 of the intake air is finally sucked into the cylinder 123 and is located above the cylinder 123, that is, near the plug 113, and the spray 125 is a deflected spray having a large upward component in FIG. The spray 125 mainly mixes with the swirl 121 of the intake air to form a mixture having a stoichiometric air-fuel ratio around the plug 113. Most of the rest is swirl 120 made of EGR gas, which flows under the cylinder 123 and increases the intake air amount while maintaining the air-fuel ratio of the entire cylinder 123 near the stoichiometric air-fuel ratio to increase pumping loss and cooling loss. Can be reduced.
[0031]
6 and 7 show the operation of the first embodiment when the engine load is medium.
[0032]
First, according to a signal from the computer 201, the electronically controlled throttle chamber
The opening of 104 is set slightly larger than the case shown in FIGS. On the other hand, the opening of the EGR control valve 108 is set slightly smaller. As a result, when the intake valves 111a and 111b are opened during the intake stroke of the engine, the gas that is sucked into the cylinder 123 is such that the intake air that has passed through the independent intake pipe 101a is more likely to be the EGR gas that has passed through the EGR-side independent intake pipe 101b. The swirl 121 of the intake air is larger than the swirl 120 of the EGR gas. In this case, as in the case described with reference to FIGS. 4 and 5, the swirl 121 of the intake air is finally sucked into the cylinder 123 and is located above the cylinder 123, that is, near the plug 113. Since the upward component of 5 is a large deflected spray, the spray 125 can be mainly mixed with the swirl 121 of the intake air to form a mixture having a stoichiometric air-fuel ratio around the plug 113. Most of the rest is swirl 120 made of EGR gas, which flows below cylinder 123
The pumping loss and the cooling loss can be reduced by increasing the intake air amount while keeping the air-fuel ratio of the whole 123 near the stoichiometric air-fuel ratio.
[0033]
4 to 7, the ratio of the swirl 121 of the intake air or air-fuel mixture rotating counterclockwise and the swirl 120 of the EGR gas rotating clockwise varies depending on the operation state. Can be set by changing, for example, from 10% to about 200%.
[0034]
8 and 9 show the operation of the first embodiment when the engine load is large.
[0035]
First, the swirl control valve 102 is set to be opened according to a signal from the computer 201. The opening of the electronic control throttle chamber 104 is set to be larger (closer to full opening) than in the case shown in FIG. As a result, since the intake resistance of the intake pipe 101 is reduced, when the intake valves 111a and 111b are opened during the intake stroke of the engine, a large amount of fresh air is sucked from both the independent intake pipe 101a and the EGR-side independent intake pipe 101b. Can be done.
[0036]
Further, the opening of the EGR control valve 108 is set small. Further, the lift curve of the EGR-side intake valve 111b is made equal to the lift curve of the intake valve 111a so that the intake valves 111a and 111b open and close simultaneously.
[0037]
Also, at this time, the injector is sent from the computer 201 during the intake stroke of the engine.
A signal is sent to 122 to perform fuel injection. Thereby, the vaporization time and the diffusion time of the spray are prolonged to promote mixing with the intake air, and the homogeneity of the air-fuel mixture can be increased. Since the intake air amount is large, a large amount of air-fuel mixture can be formed by increasing the fuel injection amount, and a large torque can be obtained.
[0038]
FIG. 10 shows a control flowchart of the operation shown in FIGS.
[0039]
First, the computer 201 reads the engine speed, the accelerator opening, the water temperature, the intake pressure, the exhaust temperature, and the gear position from the respective sensors, and calculates the target torque based on these.
[0040]
Next, by using this torque to refer to an operation state map of engine speed-target torque and to determine whether it is a region where the EGR stratified operation is performed or a region where the homogeneous operation is performed, an appropriate fuel injection amount and ignition timing To determine.
[0041]
Next, when performing the EGR stratified operation, the swirl control valve 102 is closed and the fuel injection timing is set to the compression stroke of the engine. Then, the lift start crank angle of the EGR side intake valve 111b is set earlier.
[0042]
On the other hand, when the EGR stratified operation is not performed, that is, when the homogeneous operation is performed, the swirl control valve 102 is opened, and the fuel injection timing is set to the intake stroke of the engine. The lift start of the EGR-side intake valve 111b is set equal to that of the intake valve 111a.
[0043]
Next, when the engine enters the exhaust-intake stroke, the intake valves 111a and 111b operate as determined above. That is, when performing stratified operation, the intake valve
111b opens first and the EGR gas flows into the cylinder 123 to form the swirl 120. Next, a swirl 121 of the intake air is formed. Here, the fuel is injected in the compression stroke by directing the swirl 121 of the intake air. Thereby, while forming an air-fuel mixture around the plug 113, the surroundings can be stratified with the EGR gas and combustion can be performed.
[0044]
On the other hand, when performing the homogeneous operation, the swirl control valve 102 opens, the intake valves 111a and 111b open simultaneously, and air flows in from both the independent intake pipe 101a and the EGR-side independent intake pipe 101b. Since the passage cross section is large and the resistance is small, a lot of air flows in. On the other hand, by performing the fuel injection in the intake stroke, the vaporization time can be extended, and the homogeneity of the air-fuel mixture can be improved.
[0045]
Next, ignition is performed according to the determined ignition timing. Here, the combustion is performed and the output is taken out. Subsequently, the combustion gas is discharged to the exhaust pipe 110 in the exhaust stroke. Thus, one cycle is completed, and by repeating this, the operation of the engine is performed.
[0046]
FIG. 11 shows a lift curve of the intake / exhaust valve according to the second embodiment of the present invention. Since the basic configuration of the second embodiment is the same as that of the first embodiment, the description is omitted. Regarding the variable mechanism of the intake valves 111a and 111b, a mechanism is added to not only accelerate the start of the operation of the EGR-side intake valve 111b but also reduce the lift amount of the intake valve 111a as in the first embodiment. With this configuration, the amount of intake air can be reduced while increasing the amount of swirl 120 of the EGR gas flowing into the cylinder 123, and more EGR gas can be introduced compared to the amount of intake air. In addition, pumping loss in a low load region can be reduced.
[0047]
FIG. 12 shows a lift curve of the intake / exhaust valve according to the third embodiment of the present invention. The basic configuration of the third embodiment is the same as that of the first embodiment, and a description thereof will be omitted. The variable operation mechanism of the intake valves 111a and 111b includes a mechanism for independently changing the operating angle of each valve. When performing EGR stratified combustion, the operating angles of the intake valves 111a and 111b are reduced, and the operation of the EGR-side intake valve 111b is advanced, and at the same time, the operation of the intake air-side intake valve 111a is delayed. With this configuration, the cylinder
The timing at which the swirl 120 of the EGR gas flows into the 123 and the timing at which the swirl 121 of the intake air flows in can be shifted, so that a good stratification of the mixture with the EGR gas can be achieved, and a large amount of EGR gas is introduced. Therefore, pumping loss in a low load region can be reduced.
[0048]
FIG. 13 shows a lift curve of the intake / exhaust valve according to the fourth embodiment of the present invention. The basic configuration of the fourth embodiment is the same as that of the first embodiment, and a description thereof will be omitted. The exhaust valve 112 has a variable operation mechanism for shifting the valve opening period, and the intake valve 111a has a mechanism for changing the valve operating angle. In this embodiment, the EGR-side intake valve does not need to include the variable operation mechanism. When performing the EGR stratified combustion, the closing timing of the exhaust valve 112 is delayed by 20 ° or more in crank angle. Further, the operating angle of the intake valve 111a is reduced by 20 ° or more, and at the same time, the valve opening is delayed by 20 ° or more as compared with the EGR-side intake valve 111b. With this configuration, the combustion gas returned from the exhaust valve 112 past the top dead center from the exhaust valve 112 remains in the cylinder 123, and then the EGR gas from the EGR-side intake valve 111b generates the swirl 120, and finally the intake gas Air flows in as swirl 121 through intake valve 111a. Since the EGR gas can also be introduced from the exhaust valve 112, a large amount of EGR can be introduced. Further, since there is no need to change the timing of the EGR-side intake valve 111b, it is only necessary to provide one type of variable valve actuation mechanism on each of the intake side and the exhaust side, and the structure is different from that of the second or third embodiment. Becomes easier.
[0049]
FIG. 14 shows a diagram of a stratified and homogeneous operation region on a rotation speed-torque map according to the present invention. At the same engine speed, a relatively large amount of EGR gas is introduced when the load is small, and the EGR gas decreases as the load increases. When the load further increases, the mode is switched to homogeneous combustion.
[0050]
FIG. 15 shows a stratified and homogeneous operation region on a rotational speed-torque map according to the prior art, and FIG. 16 shows a comparison of fuel consumption by load between the prior art and the present invention.
[0051]
In the prior art, stratification is mainly performed by air. However, since EGR gas is used in the present invention, the specific heat ratio of the gas in the cylinder increases during the expansion stroke of the engine, and the efficiency of the engine improves. Further, since the mixture of the EGR gas and the combustible mixture is minimized, deterioration of the combustion of the mixture can be prevented, and the combustion efficiency is improved. For this reason, when compared at the same engine speed and load, the fuel consumption can be reduced.
[0052]
Furthermore, in the prior art, in order to maintain the activity of the lean NOx catalyst, it is necessary to apply a rich spike at regular intervals, and the fuel consumption during this time deteriorates. Thus, the overall fuel consumption can be further reduced in the present invention.
[0053]
In the above embodiments, the basic concept of the stoichiometric mixture combustion by the EGR stratification is described, and the scope of the present invention is not necessarily limited to this. For example, the number of intake passages or the shape of the intake passages Even if the air flow changes, an intake control valve or a swirl control valve that partially blocks those passages is introduced, and EGR gas is introduced into the blocked portion, and the flammable mixture is mixed with the EGR gas by changing the valve timing. Any configuration that stratifies is obviously included in the scope of the present invention.
[0054]
Furthermore, although the present embodiment describes a naturally aspirated engine, if stratified charge combustion using EGR gas can be performed, the same operation can be performed for a supercharged engine. In this case, since the pressure of the intake air is higher than the atmospheric pressure, the intake air amount can be increased even if the EGR gas is supplied, and the stratified operation range can be made wider than in the case of natural intake.
[0055]
In addition, although a total of four embodiments are shown for the variable valve operation mechanism, a similar effect can be obtained by using a combination of two or more of them, and these are clearly included in the scope of the present invention.
[0056]
【The invention's effect】
The effects of the present invention are listed as follows.
[0057]
First, since EGR gas is used, stratified charge combustion can be performed to reduce the pumping loss and improve efficiency, while keeping the air-fuel ratio always close to the stoichiometric air-fuel ratio. In addition, there is no need to use a lean NOx catalyst as in the related art, and there is an effect that deterioration of fuel efficiency due to rich spikes can be prevented. Further, there is an effect that the NOx removal rate is high and the effect of exhaust gas purification is large. Further, since it is not necessary to use both the lean NOx catalyst and the three-way catalyst, there is an effect that the cost can be reduced.
[0058]
Also, stratification of the mixture and EGR gas does not depend on the shape of the intake port or piston cavity, so that air flow during high rotation or high load is not hindered, and pumping at high output and low load is performed. This has the effect of producing an engine with low loss and good fuel economy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of the present invention as viewed from above a cylinder.
FIG. 2 is a configuration diagram of the first embodiment of the present invention as viewed from the side of the cylinder.
FIG. 3 is a lift curve of an intake / exhaust valve according to the first embodiment.
FIG. 4 is a diagram showing an operation state at a low load in the first embodiment when viewed from above.
FIG. 5 is a diagram of an operation state at a low load as viewed from the side in the first embodiment.
FIG. 6 is a diagram showing the operation state at the time of a medium load in the first embodiment as viewed from above.
FIG. 7 is a side view of the operating state of the first embodiment under a medium load.
FIG. 8 is a view of the operation state under a high load in the first embodiment, as viewed from above.
FIG. 9 is a diagram illustrating an operation state under a high load as viewed from the side in the first embodiment.
FIG. 10 is an operation flowchart in the first embodiment.
FIG. 11 is a lift curve of an intake / exhaust valve according to a second embodiment of the present invention.
FIG. 12 is a lift curve of an intake / exhaust valve according to a third embodiment of the present invention.
FIG. 13 is a lift curve of an intake / exhaust valve according to a fourth embodiment of the present invention.
FIG. 14 is a diagram of a stratified and homogeneous operation region on a rotation-torque map according to the present invention.
FIG. 15 is a diagram of a stratified and homogeneous operation region on a rotation-torque map according to the related art.
FIG. 16 is a comparison diagram of fuel consumption between the present invention and the prior art.
[Explanation of symbols]
101: intake pipe, 101a: independent intake pipe, 101b: EGR side independent intake pipe,
102: swirl control valve, 103: collector, 104: electronic control throttle chamber, 105: air flow meter, 106: air cleaner, 107: piston, 108: EGR control valve, 109: EGR passage, 110: exhaust pipe, 111a: intake air Side intake valve, 111b ... EGR side intake valve, 112 ... exhaust valve, 113 ... spark plug, 115 ... three-way catalyst, 120 ... swirl by EGR gas, 121 ... swirl by intake air, 122 ... injector, 123 ... cylinder , 125 ... fuel spray, 201 ... computer.

Claims (11)

In an internal combustion engine provided with a means for directly injecting fuel into a cylinder and a means for recirculating or retaining the exhaust gas after combustion in the cylinder, a portion mainly composed of an exhaust gas recirculated gas, An internal combustion engine which is divided into a portion mainly composed of an air-fuel mixture and stratified so that the portion mainly composed of the intake air or the flammable air-fuel mixture exists near an ignition plug. In an internal combustion engine having means for directly injecting fuel into a cylinder, means for stratifying or homogenizing the air-fuel mixture according to the load of the internal combustion engine are provided, and in any case, the air-fuel ratio of the air-fuel mixture in the cylinder is provided. The internal combustion engine is controlled so as to be close to a stoichiometric air-fuel ratio necessary for operating the three-way catalyst. 3. The internal combustion engine according to claim 2, wherein the means for stratifying or homogenizing the air-fuel mixture in accordance with the load of the internal combustion engine is means for controlling the timing of opening and closing the intake valve. In an internal combustion engine equipped with means for directly injecting fuel into a cylinder, having means for generating two swirls, and when performing stratified combustion, one of its compositions is mainly air or a flammable mixture, The other is an internal combustion engine that mainly generates EGR gas and generates swirls having different rotation directions. 5. The internal combustion engine according to claim 4, wherein the spray from the injector is deflected spray, and when performing stratified combustion, the spray direction and the spray penetration force are adjusted so as to mix with a swirl mainly composed of air. In an internal combustion engine having a means for directly injecting fuel into a cylinder and an EGR means for recirculating exhaust gas to an intake pipe, two or more intake valves, and the valve opening timing and lift amount of the intake valves are changed. Means, and an intake control valve for partially closing the intake passage between the intake valve and the intake valve. The intake pipe side outlet of the EGR gas passage is configured to open into the closed intake pipe. An internal combustion engine, wherein an intake valve connected to a pipe opens at least 20 ° earlier than other intake valves by a crank angle. In an internal combustion engine having a means for directly injecting fuel into a cylinder and an EGR means for recirculating exhaust gas to an intake pipe, two or more intake valves, and the opening timing and lift amount of these intake valves are changed. And an intake control valve for partially closing the intake passage between the intake passage and the intake valve. The intake pipe side outlet of the EGR gas passage is configured to open into the closed intake pipe. An internal combustion engine characterized in that the lift amounts of other intake valves are smaller than the lift amounts of intake valves connected to the intake valves. In an internal combustion engine having a means for directly injecting fuel into a cylinder and an EGR means for recirculating exhaust gas to an intake pipe, two or more intake valves, and the valve opening timing and lift amount of the intake valves are changed. Means, and an intake control valve for partially closing the intake passage between the intake valve and the intake valve, wherein the intake pipe side outlet of the EGR gas passage is configured to open into the closed intake pipe, and the closed The opening start of the intake valve connected to the intake pipe is earlier than the opening start of the other intake valve, and the opening period of the intake valve connected to the closed intake pipe is longer than the opening period of the other intake valve. An internal combustion engine characterized by being long. In claim 8, comprising one or more exhaust valves, and means for changing the opening and closing valve timing and the lift amount of the exhaust valves, based on the opening timing of the intake valve connected to the closed intake pipe, An internal combustion engine wherein the closing timing of the exhaust valve is delayed. In an internal combustion engine provided with a means for directly injecting fuel into a cylinder and an EGR means for recirculating exhaust gas to an intake pipe, two or more intake valves, one or more exhaust valves, and those intake and exhaust valves A means for changing the opening / closing valve timing and the lift amount, and an intake control valve for partially closing the intake passage between the intake valve and the intake valve, wherein the intake pipe side outlet of the EGR gas passage is opened in the closed intake pipe. And, based on the opening period of the intake valve connected to this intake pipe, the opening start of other intake valves is delayed more than this, and the opening period is reduced, An internal combustion engine characterized in that the closing timing of the exhaust valve is delayed in accordance with this. 2. The internal combustion engine according to claim 1, wherein fuel is injected in a latter half of a compression stroke during stratified charge combustion, and fuel is injected in an intake stroke during homogeneous charge combustion.

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