JPH10252486A - Intake/exhaust device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of knocking by forming an EGR gas layer over the whole circumference of the peripheral part of a combustion chamber. SOLUTION: Communicating passages 18, 19, 20, 21 are arranged in this intake/exhaust device so that intake ports 6, 7, 8, 9 of air cylinders 2, 3, 4, 5 in an intake stroke and exhaust ports 13, 12, 11, 10 of air cylinders 5, 4, 3, 2 in an exhaust stroke are communicated with each other, thereby exhaust having high exhaust pressure of the air cylinder in the exhaust stroke is supplied as EGR gas to the air cylinder in the intake stroke. The negative pressure of the intake port is large at the time of a light load and blow down pressure is large at the time of a high load, therefore differential pressure between the intake port of a predetermined air cylinder and the exhaust port of the air cylinder corresponding to the predetermined air cylinder is always large. Therefore, EGR gas pressure can be sufficiently increased, and sufficiently strong intercylinder swirl can be produced in the combustion chamber of the air cylinder in the intake stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an intake and exhaust device for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a swirl port is provided to generate in-cylinder swirl, and furthermore, an intake valve of an internal combustion engine that generates in-cylinder swirl by opening an exhaust valve for a predetermined period before a bottom dead center of intake stroke. Exhaust devices are known. In this intake and exhaust device, the two in-cylinder swirls combine to form a swirl flow over the entire circumference of the combustion chamber, and form an EGR gas layer all around the periphery of the combustion chamber. Therefore, N
Ox generation can be reduced and knocking can be suppressed. Further, this intake / exhaust device forms a relatively rich air-fuel mixture near the spark plug at the center of the combustion chamber. for that reason,
The ignitability and combustibility of the air-fuel mixture can be kept high and the amount of generated HC can be reduced. An example of this type of intake and exhaust device for an internal combustion engine is disclosed in, for example, JP-A-5-280356.

In addition, an EGR gas is injected into a combustion chamber from a face portion of an intake valve, or a pressurized air-fuel mixture is injected into a combustion chamber from a face portion of an intake valve to generate in-cylinder swirl. Exhaust devices are known. This intake / exhaust device can forcibly stir the air-fuel mixture sucked into the combustion chamber by the in-cylinder swirl and burn a lean air-fuel mixture containing a large amount of exhaust gas or air. The amount of generation can be reduced. An example of this type of intake and exhaust device for an internal combustion engine is disclosed in, for example,
There is one described in JP-A-112415.

Further, an intake port and an exhaust port of the same cylinder are communicated with each other, and the direction of injection of EGR gas injected into the combustion chamber via the intake port is switched to deactivate the in-cylinder swirl. Intake and exhaust devices are known. This intake / exhaust device mixes fresh air and EGR gas by in-cylinder swirl. Therefore, good combustion can be performed, and the generation amount of HC, NOx, and the like can be reduced. An example of this type of intake / exhaust device for an internal combustion engine is disclosed in Japanese Utility Model Laid-Open No. 2-40961.

Further, the combustion chambers of a plurality of cylinders are communicated by a connecting path, and the air-fuel mixture in the combustion chambers of the cylinders in the compression stroke is injected into the combustion chambers of the cylinders in the suction stroke, so that the mixture in the combustion chambers of the cylinders in the suction stroke. BACKGROUND ART An intake and exhaust device for an internal combustion engine that generates in-cylinder swirl is known. This intake / exhaust device can improve the combustion by stirring the air-fuel mixture by the in-cylinder swirl. An example of this type of intake and exhaust device for an internal combustion engine is disclosed in, for example, JP-A-54-16010.

Also, there is known an intake / exhaust device for an internal combustion engine in which two intake passages join at an upstream portion of a single intake valve, and an EGR gas inlet is provided only in one of the intake passages. I have. This intake / exhaust device can generate in-cylinder swirl by increasing the intake flow velocity in an intake passage not provided with an EGR gas inlet, and stir the air-fuel mixture to improve combustion. An example of this type of intake / exhaust device for an internal combustion engine is disclosed, for example, in Japanese Patent Application Laid-Open No. 57-146042.

Further, there is known an intake and exhaust device for an internal combustion engine in which an opening of an EGR gas passage is provided downstream of a throttle of a helical port. This intake / exhaust device can prevent the EGR gas from passing through the throttle of the helical port, and can reduce the pump loss related to the EGR gas. An example of this type of intake and exhaust device for an internal combustion engine is disclosed in, for example, JP-A-6-17.
There is one described in U.S. Pat.

[0008]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No.
The intake and exhaust system of the internal combustion engine disclosed in Japanese Patent Publication No. 280356 injects air-fuel mixture into the combustion chamber via the intake valve even after the intake stroke bottom dead center. Therefore, even if the EGR gas layer is formed over the entire periphery of the combustion chamber before the intake stroke bottom dead center, the EGR gas on the entire periphery of the combustion chamber is mixed with the air-fuel mixture after the intake stroke intake bottom dead center. Will be replaced by As a result, N
Ox generation cannot be sufficiently reduced, and knocking cannot be sufficiently suppressed. Further, the EGR gas injected through the exhaust valve before the intake stroke bottom dead center and the air-fuel mixture injected through the intake valve after the intake stroke bottom dead center are mixed after the intake stroke intake bottom dead center. Resulting in. Therefore, a rich air-fuel mixture cannot be sufficiently formed near the ignition plug in the center of the combustion chamber. As a result, the ignitability and the combustibility of the air-fuel mixture cannot be kept sufficiently high, and the amount of generated HC cannot be sufficiently reduced.

Further, in the intake and exhaust system of an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 54-112415, when EGR gas is injected into a combustion chamber, the pressure of the EGR gas is not high enough to guide the EGR gas from an exhaust pipe. , Cannot generate sufficiently strong in-cylinder swirl. Therefore, the air-fuel mixture sucked into the combustion chamber cannot be sufficiently stirred, and the EGR gas layer cannot be formed over the entire periphery of the combustion chamber. As a result, similarly to the intake and exhaust device of the internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 5-280356, the amount of NOx generated cannot be sufficiently reduced,
The occurrence of knocking cannot be sufficiently suppressed. When a pressurized air-fuel mixture is injected into a combustion chamber, a compressor must be operated to pressurize the air-fuel mixture. As a result, the cost for installing the compressor increases, and furthermore, the fuel efficiency deteriorates as required for the operation of the compressor.

In the intake / exhaust device for an internal combustion engine disclosed in Japanese Utility Model Laid-Open Publication No. 2-40961, the intake port and the exhaust port of the same cylinder are connected to each other. And exhaust of the exhaust gas at the same time. Further, since the injection of the EGR gas into the combustion chamber is performed during the suction stroke, the exhaust pressure during the injection of the EGR gas is not sufficiently high. That is, the pressure of the EGR gas is not sufficiently high. Therefore, a sufficiently strong in-cylinder swirl cannot be generated, the fresh air and the EGR gas cannot be sufficiently stirred, and an EGR gas layer cannot be formed over the entire periphery of the combustion chamber. As a result, similarly to the intake and exhaust system of the internal combustion engine disclosed in JP-A-5-280356, the amount of generated NOx cannot be reduced sufficiently, and the occurrence of knocking cannot be sufficiently suppressed.

The intake and exhaust system for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 54-16010 can generate in-cylinder swirl by an air-fuel mixture, but cannot generate in-cylinder swirl by EGR gas. Therefore, the EGR gas layer cannot be formed over the entire periphery of the combustion chamber. As a result, similarly to the intake and exhaust system of the internal combustion engine disclosed in JP-A-5-280356, the amount of generated NOx cannot be reduced sufficiently, and the occurrence of knocking cannot be sufficiently suppressed.

Further, in the intake and exhaust system of the internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 57-146042, the pressure of the EGR gas injected into the combustion chamber is not sufficiently high. The EGR gas layer cannot be formed over the entire periphery of. As a result, the
Similarly to the intake and exhaust device of the internal combustion engine of 280356,
The amount of generated NOx cannot be sufficiently reduced, and the occurrence of knocking cannot be sufficiently suppressed.

The intake and exhaust system for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 6-173781 is similar to the intake and exhaust system for an internal combustion engine disclosed in Japanese Utility Model Application Laid-Open No. 2-40961. Because of the communication, the pressure of the EGR gas is not sufficiently high. Therefore, a sufficiently strong in-cylinder swirl cannot be generated, the fresh air and the EGR gas cannot be sufficiently agitated, and the EG is swept around the entire periphery of the combustion chamber.
The R gas layer cannot be formed. As a result, similarly to the intake / exhaust device for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 5-280356, the amount of generated NOx cannot be sufficiently reduced, and the occurrence of knocking cannot be sufficiently suppressed.

[0014] In view of the above problems, the present invention provides a sufficiently strong in-cylinder swirl while avoiding an increase in cost for installing a compressor for pressurizing EGR gas and the like and a decrease in fuel efficiency due to operation of the compressor. By forming an EGR gas layer all around the periphery of the combustion chamber, knocking can be suppressed, the ignitability and combustibility of the air-fuel mixture can be kept high, and the generation amount of NOx and HC can be reduced. An object of the present invention is to provide an intake and exhaust device for an internal combustion engine.

[0015]

According to the first aspect of the present invention, there is provided an intake system for an internal combustion engine having a plurality of cylinders each having an intake port opened and closed by an intake valve and an exhaust port opened and closed by an exhaust valve. In the exhaust device, the intake port of one cylinder and the exhaust port of the other cylinder communicate with each other through a communication path, and when the one cylinder is in an intake stroke,
An intake / exhaust device for an internal combustion engine is provided, wherein the other cylinder performs an exhaust stroke.

According to the first aspect of the present invention, the intake and exhaust system for an internal combustion engine supplies exhaust gas having a high exhaust pressure of a cylinder in an exhaust stroke to the cylinder in an intake stroke as EGR gas. That is, the EGR passage communicates the exhaust port and the intake port of the different cylinders. Therefore, the pressure of the EGR gas can be sufficiently increased, a sufficiently strong in-cylinder swirl can be generated in the combustion chamber of the cylinder in the intake stroke, and the EGR gas layer is formed over the entire periphery of the combustion chamber. be able to. As a result, occurrence of knocking can be suppressed, and the amount of generated NOx can be reduced. Further, in the combustion chamber of the cylinder in the intake stroke, a rich air-fuel mixture can be formed near the ignition plug at the center of the combustion chamber. As a result, the ignitability and combustibility of the air-fuel mixture can be kept high, and the amount of generated HC can be reduced. In addition, since a compressor for pressurizing the EGR gas is not required, it is possible to avoid deterioration of fuel efficiency caused when the compressor is operated.
In addition, since the intake port of each cylinder and the exhaust port of the cylinder corresponding to that cylinder communicate with each other through communication passages, the influence of intake and exhaust pulsations of other cylinders is small, and the EGR gas can be distributed well. Can be. Also, at a light load, the intake manifold, that is, the negative pressure at the intake port is large, and at a high load, the blowdown pressure is large, so that the differential pressure between the intake port of a given cylinder and the exhaust port of the cylinder corresponding to that cylinder is always constant. As a result, high-pressure EGR gas can always be supplied.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a cylinder head of an embodiment of an intake / exhaust device for an internal combustion engine according to the present invention. In FIG. 1, reference numeral 1 denotes a cylinder head, and reference numerals 2 to 5 denote a first cylinder, a second cylinder, a third cylinder, and a fourth cylinder, respectively. 6-9 are
These are the intake ports of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, respectively. Reference numerals 10 to 13 denote exhaust ports of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, respectively. 14
Reference numerals 17 to 17 denote EGR gas blowing pipes of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, respectively. An EGR passage 18 connects the intake port 6 of the first cylinder and the exhaust port 13 of the fourth cylinder. 19 is the intake port 7 of the second cylinder
And an EGR passage that communicates with the exhaust port 12 of the third cylinder. Reference numeral 20 denotes an EGR passage that connects the intake port 8 of the third cylinder and the exhaust port 11 of the second cylinder. An EGR passage 21 communicates the intake port 9 of the fourth cylinder and the exhaust port 10 of the first cylinder. 22 to 25 are EG
This is a reed valve provided in the R passages 18 to 21. 26-
Reference numeral 29 denotes control valves provided in the EGR passages 18 to 21, respectively.

As shown in FIG. 1, the EGR gas outlet pipes 14 to 17 are arranged off-center with respect to the intake ports 6 to 9, respectively. Therefore, in-cylinder swirl can be generated in the direction of the arrow in the figure. Reed valves 22 to 25 provided in EGR passages 18 to 21, respectively
Prevents the backflow of EGR gas flowing from the exhaust port to the intake port. The control valves 26 to 29 are respectively EG
The EGR gas flow rate flowing through the R passages 18 to 21 is determined by the ECU.
Control based on signals from the Each EGR passage 18-2
1 are independent of each other, and the EGR gases in each of the EGR passages 18 to 21 do not mix with each other. Therefore, the intake / exhaust pulsation of the cylinder hardly affects the cylinder that is not communicated with the cylinder. The exhaust port side end of each of the EGR passages 18 to 21 is provided as close to the combustion chamber as possible. Therefore, the exhaust gas from each combustion chamber can reach each of the EGR passages 18 to 21 without decreasing the pressure when passing through each of the exhaust ports 10 to 13. Further, the ends of the EGR outlet pipes 14 to 17 are also provided as close to the combustion chamber as possible. for that reason,
The EGR gas from each of the EGR passages 18 to 21 can reach each combustion chamber without lowering the pressure when passing through each of the intake ports 6 to 9.

FIG. 2 is a characteristic diagram showing stroke timing of each cylinder of the cylinder head of FIG. In FIG. 2, a solid line bidirectional arrow indicates an opening period of the intake valve on the side of the EGR gas discharge pipe, a dashed line bidirectional arrow indicates a valve opening period of the intake valve on the opposite side of the EGR gas discharge pipe, and a two-dot chain line. The two-way arrow indicates the opening period of the exhaust valve (common to the two exhaust valves of each cylinder), and the white arrow indicates the blowdown E
4 shows the flow of GR gas. As shown in FIG.
The opening timing of the intake valve on the GR gas outlet pipe side is no longer than the opening timing of the intake valve on the opposite side of the EGR gas outlet pipe of that cylinder, and the closing timing of the intake valve on the EGR gas outlet pipe side of each cylinder. Is later than the closing timing of the intake valve on the opposite side of the EGR gas outlet pipe of that cylinder.
As a result, in-cylinder swirl can be generated more effectively in the combustion chamber of each cylinder.

Referring to FIGS. 1 and 2, the flow of EGR gas from one cylinder to the other cylinder, which is connected to each other by an EGR passage, will be described below. As shown in FIG.
The intake and exhaust device of the internal combustion engine according to the present embodiment has the first cylinder EG.
R gas outlet pipe 14, EGR passage 18, control valve 26
Further, the intake port 6 of the first cylinder and the exhaust port 13 of the fourth cylinder communicate with each other via the reed valve 22. As shown in FIG. 2, the intake stroke of the first cylinder 2 (opening period of the intake valve on the side of the EGR gas outlet pipe of the first cylinder) and the exhaust stroke of the fourth cylinder 5 (opening of the exhaust valve of the fourth cylinder) The period) overlaps with the period immediately before the end of the intake stroke of the first cylinder 2 (the period immediately after the start of the exhaust stroke of the fourth cylinder 5). The exhaust pressure of the combustion chamber of a cylinder is highest during the period immediately after the start of the exhaust stroke of the cylinder. Therefore, as indicated by a white arrow in FIG. 2, the highest pressure exhaust from the combustion chamber of the fourth cylinder 5 during the period immediately after the start of the exhaust stroke is caused by the blowdown of the fourth cylinder 5,
The EGR gas reaches the intake port 6 of the first cylinder via the EGR passage 18 and the like. EG reaching intake port 6
Since the R gas has a sufficiently high pressure, a sufficiently strong in-cylinder swirl can be formed in the combustion chamber of the cylinder 2. As a result, an EGR gas layer can be formed at the periphery of the combustion chamber of the first cylinder 2. The high-pressure EGR gas from the fourth cylinder 5 reaches the combustion chamber of the first cylinder 2 during a period immediately before the end of the intake stroke of the first cylinder 2, and thus inhales a sufficiently strong in-cylinder swirl of the first cylinder 2. It can be maintained until the ignition timing immediately after the end of the stroke.

Further, as shown in FIG. 1, the intake / exhaust system for an internal combustion engine according to the present embodiment includes an EGR gas blowing pipe 15 of a second cylinder, an EGR passage 19, a control valve 27, and a reed valve 2.
3, the intake port 7 of the second cylinder and the exhaust port 12 of the third cylinder communicate with each other. As shown in FIG. 2, the intake stroke of the second cylinder 3 and the exhaust stroke of the third cylinder 4 are defined as a period immediately before the end of the intake stroke of the second cylinder 3 (a period immediately after the start of the exhaust stroke of the third cylinder 4). ). As shown by the white arrow in FIG. 2, the blowdown of the third cylinder 4
The highest-pressure exhaust gas from the combustion chamber of the third cylinder 4 during the period immediately after the start of the exhaust stroke reaches the intake port 7 of the second cylinder via the EGR passage 19 and the like as EGR gas. Since the EGR gas reaching the intake port 7 has a sufficiently high pressure, a sufficiently strong in-cylinder swirl can be formed in the combustion chamber of the second cylinder 3. As a result, an EGR gas layer can be formed at the periphery of the combustion chamber of the second cylinder 3. The high-pressure EGR gas from the third cylinder 4 reaches the combustion chamber of the second cylinder 3 during a period immediately before the end of the intake stroke of the second cylinder 3, and thus inhales a sufficiently strong swirl in the cylinder of the second cylinder 3. It can be maintained until the ignition timing immediately after the end of the stroke.

Further, as shown in FIG. 1, the intake / exhaust system for an internal combustion engine according to the present embodiment includes an EGR gas blowing pipe 16 of a third cylinder, an EGR passage 20, a control valve 28, and a reed valve 2.
4, the intake port 8 of the third cylinder and the exhaust port 11 of the second cylinder communicate with each other. As shown in FIG. 2, the intake stroke of the third cylinder 4 and the exhaust stroke of the second cylinder 3 are defined as a period immediately before the end of the intake stroke of the third cylinder 4 (a period immediately after the start of the exhaust stroke of the second cylinder 3). ). As shown by the white arrow in FIG. 2, the blowdown of the second cylinder 3
The highest-pressure exhaust gas from the combustion chamber of the second cylinder 3 during the period immediately after the start of the exhaust stroke reaches the intake port 8 of the third cylinder via the EGR passage 20 and the like as EGR gas. Since the EGR gas reaching the intake port 8 has a sufficiently high pressure, a sufficiently strong in-cylinder swirl can be formed in the combustion chamber of the third cylinder 4. As a result, an EGR gas layer can be formed at the periphery of the combustion chamber of the third cylinder 4. The high-pressure EGR gas from the second cylinder 3 reaches the combustion chamber of the third cylinder 4 during a period immediately before the end of the intake stroke of the third cylinder 4, and thus inhales a sufficiently strong in-cylinder swirl of the third cylinder 4. It can be maintained until the ignition timing immediately after the end of the stroke.

Further, as shown in FIG. 1, the intake / exhaust system for an internal combustion engine according to the present embodiment includes a fourth cylinder EGR gas blowing pipe 17, an EGR passage 21, a control valve 29, and a reed valve 2.
The intake port 9 of the fourth cylinder and the exhaust port 10 of the first cylinder communicate with each other through the port 5. As shown in FIG. 2, the intake stroke of the fourth cylinder 5 and the exhaust stroke of the first cylinder 2 are defined as a period immediately before the end of the intake stroke of the fourth cylinder 5 (a period immediately after the start of the exhaust stroke of the first cylinder 2). ). As shown by the white arrow in FIG.
The highest-pressure exhaust gas from the combustion chamber of the first cylinder 2 during the period immediately after the start of the exhaust stroke reaches the intake port 9 of the fourth cylinder via the EGR passage 21 and the like as EGR gas. Since the EGR gas reaching the intake port 9 has a sufficiently high pressure, a sufficiently strong in-cylinder swirl can be formed in the combustion chamber of the fourth cylinder 5. As a result, an EGR gas layer can be formed at the periphery of the combustion chamber of the fourth cylinder 5. The high-pressure EGR gas from the first cylinder 2 reaches the combustion chamber of the fourth cylinder 5 during a period immediately before the end of the intake stroke of the fourth cylinder 5, and thus inhales a sufficiently strong in-cylinder swirl of the fourth cylinder 5. It can be maintained until the ignition timing immediately after the end of the stroke.

Therefore, the intake / exhaust device for an internal combustion engine of the present embodiment can reduce the amount of NOx generated at the periphery of the combustion chamber of all cylinders, and can suppress the occurrence of knocking. Therefore, the compression ratio of the combustion chamber of each cylinder is increased,
Fuel efficiency can be improved. Further, with the above-described configuration, high-pressure EGR gas can be supplied to the combustion chambers of all the cylinders, so that the air compressor for pressurizing the EGR gas can be eliminated, and the fuel consumption by operating the air compressor can be reduced. Deterioration can be avoided. In addition, a sufficiently strong in-cylinder swirl can be generated in the combustion chambers of all cylinders, so that a swirl port that reduces the output of the internal combustion engine can be eliminated.

In the above-described embodiment, the intake ports and exhaust ports of the first and fourth cylinders and the intake ports and exhaust ports of the second and third cylinders are communicated with each other. Then, the intake port and the exhaust port of the first cylinder and the third cylinder, and the intake port and the exhaust port of the second cylinder and the fourth cylinder can be communicated with each other. In addition, the intake port and the exhaust port of any combination of cylinders can be communicated with each other when one cylinder is in the intake stroke and the other cylinder is in the exhaust stroke.

[0027]

According to the present invention, a sufficiently strong in-cylinder swirl is generated while avoiding an increase in cost for installing a compressor for pressurizing EGR gas and the like and a decrease in fuel efficiency due to the operation of the compressor. EGR over the entire periphery of the combustion chamber
By forming the gas layer, the occurrence of knocking can be suppressed, the ignitability and combustibility of the air-fuel mixture can be kept high, and the generation amount of NOx and HC can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylinder head of an embodiment of an intake and exhaust device for an internal combustion engine of the present invention.

FIG. 2 is a characteristic diagram showing stroke timing of each cylinder of the cylinder head of FIG. 1;

[Explanation of symbols]

 2-5: cylinder 6-9: intake port 10-13: exhaust port 18-21: EGR passage

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 25/07 580 F02M 25/07 580A 580B

Claims (1)

[Claims] 1. An intake / exhaust system for an internal combustion engine having a plurality of cylinders each having an intake port opened and closed by an intake valve and an exhaust port opened and closed by an exhaust valve. An intake / exhaust device for an internal combustion engine, characterized in that the exhaust ports of the cylinders are communicated with each other through communication paths, and when the one cylinder is in an intake stroke, the other cylinder is in an exhaust stroke.