JP2011214552A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine which is favorably configured for taking measures to suppress impaired engine performance caused by a change in the operating region when a supercharger and a configuration for exhaust gas recirculation are included.SOLUTION: An exhaust branch pipe 30 is in communication with a position upstream of a turbine 44, and an exhaust valve group Ex1 consists of exhaust valves to open and close an exhaust port in communication with the exhaust branch pipe 30, while another exhaust branch pipe 32 is in communication with a position downstream of the turbine 44. A valve group Ex2 consists of exhaust valves to open and close an exhaust port having communication with the exhaust branch pipe 32. The exhaust valve to open and close the exhaust port having communication with an EGR passage 50 in the cylinder 4 belongs to the exhaust valve group Ex1. The internal combustion engine is equipped with a variable dynamic valve system to drive the exhaust valves. By this variable dynamic valve system, the correlation between the valve opening characteristics of the exhaust valves belonging to the group Ex1 and the valve opening characteristics of the exhaust valves belonging to the group Ex2 is made equal over the different cylinders 1, 2, 3, 4, and the valve opening characteristics of the exhaust valves belonging to Ex1 are made different from those of the exhaust valves belonging to Ex2.

Description

  The present invention relates to an internal combustion engine.

  Conventionally, for example, as disclosed in JP 2003-506619A, a configuration in which exhaust gas is recirculated from a specific cylinder to an intake system in a multi-cylinder internal combustion engine is known. In this publication, the scavenging performance of exhaust gas when exhaust gas recirculation (EGR) is performed in a supercharged internal combustion engine is examined. That is, in the above publication, “in a supercharged internal combustion engine, exhaust gas recirculation is possible only in an operating state where the exhaust gas back pressure exceeds the boost pressure, but in this case, the cylinder inlet has a higher pressure than the cylinder outlet. "There is a problem that a positive scavenging gradient cannot be established." In order to cope with such a problem, in the configuration according to the above publication, exhaust gas is extracted for EGR from only a specific and single cylinder of the internal combustion engine.

JP-T-2003-506619 Japanese Patent Laid-Open No. 5-263671 JP 2009-215914 A

  In the configuration in which exhaust gas recirculation is performed in a supercharged internal combustion engine, the performance of the internal combustion engine may be deteriorated if appropriate measures are not taken according to the operating region. For example, in an internal combustion engine equipped with a supercharger, the pressure in the surge tank becomes larger than the exhaust pressure at the time of high supercharging (particularly at the time of high supercharging in the low speed range). When such a pressure relationship is established, the scavenging performance may be deteriorated at the exhaust gas scavenging timing. The inventor of the present application has conducted earnest research, and in the case where a supercharger and an exhaust gas recirculation configuration are provided, in taking measures to suppress the deterioration of the performance of the internal combustion engine due to fluctuations in the operation region. A suitable configuration has been found.

  The present invention has been made to solve the above-described problems. In the case where a supercharger and a configuration for exhaust gas recirculation are provided, the performance of the internal combustion engine is impaired due to a change in the operation region. An object of the present invention is to provide an internal combustion engine having a configuration suitable for taking measures to suppress.

In order to achieve the above object, a first invention is an internal combustion engine,
A plurality of cylinders each having two or more exhaust ports;
An EGR passage communicating with some exhaust ports of the two or more exhaust ports in some cylinders of the plurality of cylinders;
A first exhaust passage communicating with a part of the two or more exhaust ports in each of the cylinders other than the part of the plurality of cylinders;
A second exhaust passage communicating with another exhaust port other than the partial exhaust port communicating with the first exhaust passage in each of the other cylinders of the plurality of cylinders;
A main exhaust passage communicating with the first exhaust passage at a first position and communicating with the second exhaust passage at a second position different from the first position;
A supercharger having a turbine provided at a position downstream of the first position and upstream of the second position in the main exhaust passage;
The some cylinders of the plurality of cylinders communicate with other exhaust ports other than the some exhaust ports communicating with the EGR passage, and are connected to the main exhaust passage at an upstream position or a downstream position of the turbine. A third exhaust passage in communication;
An exhaust valve provided in each of the two or more exhaust ports of the plurality of cylinders;
A group of exhaust valves that opens and closes an exhaust port that communicates with an upstream position of the turbine is a first exhaust valve group, and a group of exhaust valves that opens and closes an exhaust port that communicates with a downstream position of the turbine is a second exhaust valve group, When the third exhaust passage communicates with the main exhaust passage at the turbine downstream position, an exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group. When the three exhaust passages communicate with the main exhaust passage at the turbine upstream position, the exhaust valve for opening and closing the exhaust port communicating with the EGR passage belongs to the second exhaust valve group. A relative relationship between an opening characteristic of an exhaust valve belonging to one exhaust valve group and an opening characteristic of an exhaust valve belonging to the second exhaust valve group is equal among the plurality of cylinders; Belongs to 1 exhaust valve group And opening characteristics of the exhaust valve opening characteristics and exhaust valves belonging to the second exhaust valve group and the variable valve means can be different that,
It is characterized by providing.

The second invention is the first invention, wherein
The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
In the catalyst warm-up operation of the internal combustion engine, an operating angle condition for making the operating angle of the second exhaust valve group larger than the operating angle of the first exhaust valve group and the opening timing of the second exhaust valve group Control means is provided for controlling the variable valve means so as to establish a valve opening timing condition that is earlier than the valve opening timing of the first exhaust valve group.

The third invention is the first or second invention, wherein
The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
An operating angle condition for making the operating angle of the first exhaust valve group larger than the operating angle of the second exhaust valve group when the operating range of the internal combustion engine corresponds to a predetermined low speed range, and the first exhaust valve group Control means for controlling the variable valve operating means so as to establish a valve opening timing condition for making the valve opening timing earlier than the valve opening timing of the second exhaust valve group.

According to a fourth invention, in any one of the first to third inventions,
The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
When the operating range of the internal combustion engine is a predetermined medium speed range or a high speed range, and the exhaust pressure corresponds to a predetermined range greater than the intake pressure, the operating angle of the first exhaust valve group is set to that of the second exhaust valve group. The variable valve operating means so as to satisfy an operating angle condition for making the operating angle larger than an operating angle and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group. It has the control means which controls.

Moreover, 5th invention is set in any one of 1st thru | or 4th invention,
The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
The operating angle of the first exhaust valve group is set to the second exhaust valve group when the operating range of the internal combustion engine corresponds to a predetermined medium speed range or a high speed range and the exhaust pressure is equal to or higher than the intake pressure. The variable valve operating means so as to establish an operating angle condition that is larger than an operating angle of the first exhaust valve group, and a valve opening timing condition that matches the valve opening timing of the first exhaust valve group and the valve opening timing of the second exhaust valve group. It has the control means which controls.

The sixth invention is the first invention, wherein
The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
The operating angle of the first exhaust valve group is set to the operating angle of the second exhaust valve group when the operating range of the internal combustion engine corresponds to a predetermined range where the exhaust pressure is equal to or lower than the intake pressure. The variable valve operating means is controlled so as to satisfy a larger operating angle condition and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group It is characterized by including a control means.

The seventh invention is the first or sixth invention, wherein
The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
When the operating region of the internal combustion engine is a predetermined low rotation region and the exhaust pressure corresponds to a predetermined region greater than the intake pressure, the operating angle of the second exhaust valve group is set to be larger than the operating angle of the first exhaust valve group. The variable valve operating means is controlled so as to satisfy a larger operating angle condition and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group. Control means is provided.

Moreover, 8th invention is set in any one of 1st, 6th and 7th invention,
The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
The operating angle of the first exhaust valve group and the second exhaust valve when the operating region of the internal combustion engine corresponds to a predetermined region where the exhaust pressure is equal to or higher than the intake pressure when the operating region is a predetermined middle rotational region or high rotational region. The variable motion so as to satisfy an operating angle condition for matching the operating angle of the group and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group. Control means for controlling the valve means is provided.

Moreover, 9th invention is set in any one of 1st, 6th, 7th, and 8th invention,
The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
When the operating region of the internal combustion engine is in a predetermined middle rotational region or high rotational region and the exhaust pressure is in a predetermined region that is larger than a supercharging pressure by a predetermined amount or more, the operating angle of the first exhaust valve group is set to the first (2) An operating angle condition for increasing the operating angle of the exhaust valve group and a valve opening timing condition for opening the valve timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group are established. Control means for controlling the variable valve means is provided.

In a tenth aspect based on the first aspect,
Storage means for storing information defining a relative relationship of the valve opening characteristics between the first exhaust valve group and the second exhaust valve group in accordance with an operating region of the internal combustion engine;
An operation region specifying means for specifying which of the operation regions in the information corresponds to the operation region of the internal combustion engine;
In order to establish the relative relationship of the valve opening characteristics determined by the information according to the operation region specified by the operation region specifying means between the first exhaust valve group and the second exhaust valve group, Control means for controlling the variable valve means;
It is characterized by providing.

  According to the first aspect, the valve opening characteristics can be independently adjusted between the first exhaust valve group and the second exhaust valve group. In order to cope with a change in the operation region in an internal combustion engine including a supercharger and an exhaust gas recirculation configuration, the inventor of the present application "open valve characteristics of an exhaust valve group of an exhaust port communicating with a turbine upstream position" And “open valve characteristics of the exhaust valve group of the exhaust port communicating with the downstream position of the turbine”, and assigning “exhaust valve of the exhaust port communicating with the EGR passage” to any of those groups, It was found useful to adjust with. According to the first invention, the plurality of valve bodies of the internal combustion engine are appropriately assigned to the first exhaust valve group and the second exhaust valve group, and the valve opening characteristics of the plurality of valve bodies are first, It is possible to make the difference in units of two exhaust valve groups.

  According to the second aspect of the present invention, it is possible to promote warming up of the catalyst by flowing a large amount of exhaust gas behind the turbine.

  According to the third aspect of the invention, it is possible to secure turbine rotational energy and increase the amount of fresh air in the low speed range. Further, the EGR amount and the EGR gas injection can be secured for the cylinder for taking out the EGR gas.

  According to the fourth aspect of the invention, the exhaust gas temperature can be lowered according to the operating region, and the amount of EGR gas can be secured.

  According to the fifth aspect, the scavenging efficiency can be increased in a region where a large amount of exhaust gas needs to be scavenged.

  According to the sixth aspect of the invention, it is possible to prevent (suppress) the backflow of the intake air as well as improving the supercharging performance depending on the operation region.

  According to the seventh aspect of the invention, it is possible to avoid exhaust interference (increase the amount of fresh air) according to the operating region, and to ensure both the EGR amount and the turbine rotational energy.

  According to the eighth aspect of the invention, it is possible to secure the turbine rotational energy and reduce the exhaust gas temperature by securing the EGR gas amount and reducing the turbine front back pressure according to the operating region.

  According to the ninth aspect of the invention, it is possible to suppress the residual gas amount and reduce the turbine front back pressure and the excessive amount of EGR gas according to the operation region.

  According to the tenth aspect of the present invention, in the internal combustion engine including the supercharger and the exhaust gas recirculation configuration, the plurality of exhaust valves are arranged in the first exhaust valve group in consideration of the characteristics of the valve opening characteristics of each exhaust valve. And the second exhaust valve group can be appropriately distributed, and exhaust valve control corresponding to the operation region can be performed on a group basis.

It is a figure which shows the structure of the internal combustion engine concerning Embodiment 2 of this invention. It is a figure which shows the valve opening characteristic at the time of catalyst warming-up in the internal combustion engine concerning Embodiment 1 of this invention. It is a figure which shows the valve opening characteristic in the low speed area in the internal combustion engine concerning Embodiment 1 of this invention. It is a figure which shows the valve opening characteristic in the area | region where the internal combustion engine concerning Embodiment 1 of this invention becomes medium-high-speed and exhaust pressure> intake pressure (supercharging pressure). It is a figure which shows the valve opening characteristic in the area | region where it is medium-high speed and exhaust pressure> = intake pressure (supercharging pressure) in the internal combustion engine concerning Embodiment 1 of this invention. It is a figure which shows an example of the intake / exhaust pulsation characteristic at the time of low speed and high supercharging. It is a figure which shows an example of the intake / exhaust pulsation characteristic at the time of high-speed high supercharging. It is a figure which shows the structure of the internal combustion engine concerning Embodiment 2 of this invention. It is a figure which shows the valve opening characteristic in the area | region where it is low rotation and exhaust pressure <= supercharging pressure in the internal combustion engine concerning Embodiment 2 of this invention. It is a figure which shows the valve opening characteristic in the area | region where it is a low rotation and exhaust pressure> intake pressure (supercharging pressure) in the internal combustion engine concerning Embodiment 2 of this invention. FIG. 6 is a diagram showing valve opening characteristics in a region where medium and high speed, exhaust pressure ≧ intake pressure (supercharging pressure) in an internal combustion engine according to a second embodiment of the present invention. It is a figure which shows the valve opening characteristic in the area | region used as the area | region used as the area | region where it becomes a medium-high rotation, exhaust pressure >> boost pressure in the internal combustion engine concerning Embodiment 2 of this invention.

Embodiment 1 FIG.
[Configuration of Internal Combustion Engine According to First Embodiment]
1 is a diagram showing a configuration of an internal combustion engine according to a first embodiment of the present invention. The internal combustion engine according to the first embodiment is suitable for a moving body such as a vehicle. The internal combustion engine according to the first embodiment is an in-line 4-cylinder supercharged internal combustion engine. FIG. 1 shows a cylinder head 10 having cylinders 1, 2, 3 and 4. FIG. 1 also shows a turbocharger 40 (compressor 42, turbine 44) and an EGR system (EGR passage 50, EGR cooler 52).

  The cylinder head 10 is provided with an intake port and an exhaust port for each cylinder. Each of the cylinders 1, 2, 3, 4 has two intake ports. Although not labeled, each intake port is provided with an intake valve. Each intake port communicates with the surge tank 20. The surge tank 20 communicates with the intake passage 26. In the intake passage 26, a throttle 22, an intercooler 24, and an air cleaner 28 are sequentially provided upstream.

  Two exhaust ports are provided in each of the cylinder 1, the cylinder 2, the cylinder 3, and the cylinder 4. Each cylinder is provided with an exhaust valve 8a and an exhaust valve 8a. The exhaust ports provided with the exhaust valves 8 a in the cylinders 1, 2, and 3 communicate with the exhaust branch pipe 30. On the other hand, the exhaust ports provided with the exhaust valves 8 b in the cylinders 1, 2, and 3 communicate with the exhaust branch pipe 32. The exhaust branch pipe 30 and the exhaust branch pipe 32 communicate with the main exhaust passage 34.

  The cylinder 4 is connected to the exhaust system in a manner different from that of the cylinders 1, 2, and 3. The exhaust port provided with the exhaust valve 8 a in the cylinder 4 communicates with a part 32 a of the exhaust branch pipe 32. As a result, the exhaust port provided with the exhaust valve 8a in the cylinder 4 merges with the exhaust port provided with the exhaust valve 8a of the cylinders 1, 2, and 3 at the exhaust branch pipe 32, and finally the main exhaust passage. 34 communicates. On the other hand, the exhaust port provided with the exhaust valve 8 b in the cylinder 4 communicates with the EGR passage 50. The EGR passage 50 communicates with the surge tank 20 via the EGR cooler 52. Although not shown, other mechanisms such as an EGR valve constituting the EGR system may be provided as appropriate.

  The main exhaust passage 34 is provided with a start catalyst 36 (hereinafter also simply referred to as “catalyst 36”). Although not shown, the main exhaust passage 34 may be appropriately provided with an air-fuel ratio sensor, a sub oxygen sensor, an exhaust temperature sensor, and other various sensors.

  A turbine 44 is provided in the main exhaust passage 34. The turbine 44 constitutes a turbocharger 40 together with the compressor 42 disposed in the middle of the intake passage 26. The exhaust branch pipe 30 communicates with the main exhaust passage 34 upstream of the turbine 44. Thereby, the rotation of the turbine 44 can be caused by the exhaust gas collected in the exhaust branch pipe 30. On the other hand, the exhaust branch pipe 32 communicates with the main exhaust passage 34 downstream (rearward) of the turbine 44 and upstream (frontward) of the catalyst 36.

In the first embodiment, the exhaust valve 8a and the exhaust valve 8b are driven by a variable valve mechanism (not shown). This variable valve mechanism is a mechanism that can change both the operating angle and the valve opening timing.
The variable valve mechanism according to the first embodiment is configured so that the exhaust valve 8a and the exhaust valve 8b can be operated in units of a specific group, as described below. First, an exhaust valve group that opens and closes an exhaust port communicating with the upstream position of the turbine 44 is referred to as an “exhaust valve group Ex1”. In the first embodiment, the exhaust valves 8a of the cylinders 1, 2, and 3 belong to the exhaust valve group Ex1. On the other hand, an exhaust valve group that opens and closes an exhaust port communicating with the downstream position of the turbine 44 is referred to as an “exhaust valve group Ex2”. In the first embodiment, the exhaust valves 8b of the cylinders 1, 2, and 3 belong to the exhaust valve group Ex2.
Further, in the first embodiment, the exhaust valve 8a in the cylinder 4 belongs to the exhaust valve group Ex2. This is because the exhaust port provided with the exhaust valve 8 a in the cylinder 4 also communicates with the downstream position of the turbine 44 through a part 32 a of the exhaust branch pipe 32. Further, the exhaust valve 8b in the cylinder 4 belongs to the exhaust valve group Ex1.
In the first embodiment, the valve opening characteristics (working angle, lift amount, valve opening timing) of the exhaust valves 8a and 8b allocated to the two groups as described above are obtained in units of the exhaust valve groups Ex1 and Ex2. The hardware configuration and control configuration (software configuration) of the variable valve mechanism are configured so that they can be adjusted independently. In the first embodiment, the relative relationship between the valve opening characteristics of the exhaust valves belonging to the exhaust valve group Ex1 and the valve opening characteristics of the exhaust valves belonging to the exhaust valve group Ex2 (that is, the magnitude of the operating angle, It is possible to make the valve timing (relative early / late) equal among the cylinders 1, 2, 3, and 4. Specifically, for example, when the relationship of the valve opening characteristics defined by the relative relationship between the exhaust valve groups Ex1 and Ex2 is given as input information, the exhaust valves respectively belonging to the exhaust valve groups Ex1 and Ex2 What is necessary is just to take measures such as enabling the ECU 60 to execute the “control mode for realizing the relationship of the valve opening characteristics for each cylinder” in advance.

  FIG. 1 shows an ECU (Electronic Control Unit) 60. Although not shown, the internal combustion engine is provided with a crank angle sensor, an engine water temperature sensor, and other various sensors. The ECU 60 processes signals from each sensor provided in the internal combustion engine, and reflects the processing result on the operation of each actuator (specifically, a variable valve mechanism or the like).

[Operation of Internal Combustion Engine According to First Embodiment]
2 to 5 are diagrams for explaining the operation of the internal combustion engine according to the first embodiment. 2 to 5 show the valve opening characteristics (working angle, lift amount and valve opening timing) of the intake valve and the exhaust valve realized in the first embodiment, respectively. In the first embodiment, the valve opening characteristics of the exhaust valve group Ex1 and the exhaust valve group Ex2 described above are switched according to the operation region as described below. In the following description, the operating angles of the exhaust valves belonging to the exhaust valve group Ex1 are also collectively referred to simply as “the operating angle of the exhaust valve group Ex1”. Further, the opening timings of the exhaust valves belonging to the exhaust valve group Ex1 are also simply referred to as “opening timing of the exhaust valve group Ex1”.

(1-1) Catalyst Warming-up FIG. 2 is a diagram showing the valve opening characteristics at the time of catalyst warm-up in the internal combustion engine according to the first embodiment of the present invention. During catalyst warm-up operation such as during cold start or during warm-up / idle operation, the variable valve mechanism is controlled so as to satisfy the following conditions (1a) and (1b).
(1a) Working angle of the exhaust valve group Ex2> Working angle of the exhaust valve group Ex1 (1b) The opening timing of the exhaust valve group Ex2 is made earlier than the opening timing of the exhaust valve group Ex1.
As a result, most of the exhaust gas flows behind the turbine 44, and warming up of the catalyst 36 can be promoted / maintained.

(1-2) Low Speed Region FIG. 3 is a diagram showing valve opening characteristics in the low speed region in the internal combustion engine according to the first embodiment of the present invention. In the low speed range, the variable valve mechanism is controlled so as to satisfy the following conditions (2a) to (2c).
(2a) Working angle of the exhaust valve group Ex1> Working angle of the exhaust valve group Ex2 (2b) The opening timing of the exhaust valve group Ex1 is made earlier than the opening timing of the exhaust valve group Ex2.
(2c) The operating angle of the exhaust valve group Ex1 is set to 180 degrees or less.
As a result, with respect to the cylinders having the exhaust valves belonging to the exhaust valve group Ex1, the working angle is set to 180 degrees or less, and the turbine rotation energy is secured by the self-cylinder blowdown wave and the new air amount is increased by avoiding exhaust interference by the next cylinder blowdown wave. Can be planned. Further, with respect to the cylinder 4 from which EGR gas is taken out, EGR injection can be achieved even under the condition that the EGR amount is secured by the self-cylinder blowdown wave and the intake pressure> exhaust pressure.
FIG. 6 is a diagram showing an example of the intake and exhaust pulsation characteristics at the time of low speed and high supercharging. FIG. 6 is shown for explaining the operation of the first embodiment, and shows characteristics in a configuration in which the first embodiment is not applied. Looking at the area labeled A in FIG. 6, the exhaust pressure exceeds the intake pressure at the time of blowdown, but in the area A after that, the intake pressure (supercharging pressure) is superior to the exhaust pressure. Can be read.

(1-3) Medium / High-Speed, Exhaust Pressure> Intake Pressure (Supercharging Pressure) Region FIG. 4 shows medium-high speed and exhaust pressure> intake pressure (supercharging pressure) in the internal combustion engine according to the first embodiment of the present invention. It is a figure which shows the valve opening characteristic in the area | region which becomes (). In this region, the variable valve mechanism is controlled so as to satisfy the following conditions (3a) and (3b).
(3a) Working angle of the exhaust valve group Ex1> Working angle of the exhaust valve group Ex2 (3b) The valve opening timing of the exhaust valve group Ex1 is made earlier than the valve opening timing of the exhaust valve group Ex2.
As a result, the exhaust gas from the cylinders 1, 2, 3 is radiated by the turbine 44, and the exhaust gas temperature at the inlet of the catalyst 36 can be lowered. Thereby, the raise of a catalyst bed temperature can be suppressed. As a result, the λ1 operation region can be expanded. On the other hand, in the first embodiment, in the cylinder 4 communicating with the EGR passage 50, the exhaust valve 8b related to the communication with the EGR passage 50 belongs to the exhaust valve group Ex1. For this reason, the amount of EGR gas taken out from the cylinder 4 can be secured.

(1-4) Medium / High Speed, Region where Exhaust Pressure ≧ Intake Pressure (Supercharging Pressure) FIG. 5 shows medium / high speed, exhaust pressure ≧ intake pressure (supercharging pressure) in the internal combustion engine according to the first embodiment of the present invention. It is a figure which shows the valve opening characteristic in the area | region which becomes (). In this region, the variable valve mechanism is controlled so as to satisfy the following conditions (4a) and (4b).
(4a) Working angle of the exhaust valve group Ex1> Working angle of the exhaust valve group Ex2 (4b) The opening timing of the exhaust valve group Ex1 and the opening timing of the exhaust valve group Ex2 are matched.
In this region, it is necessary to scavenge a large amount of exhaust gas. Therefore, the exhaust valve group Ex2 communicating with the rear of the low back pressure turbine 44 is also opened at the blowdown time. As a result, scavenging efficiency is increased and a knock suppression effect is obtained, so that adverse effects due to a decrease in the amount of EGR gas can be suppressed.
FIG. 7 is a diagram showing an example of intake / exhaust pulsation characteristics at high speed and high supercharging. FIG. 7 is shown for explaining the operation of the first embodiment, and shows characteristics in a configuration in which the first embodiment is not applied. As shown in region B of FIG. 7, if the amount of gas flowing upstream of the turbine is large, the back pressure becomes high due to the pressure loss of the turbine.

  In the first embodiment, the ECU 60 controls the variable valve mechanism so as to satisfy the above-mentioned conditions determined for each region according to each operation region described above. The identification of which of the above operating regions (1-1) to (1-4) corresponds to the current operating region is based on various sensor values of the internal combustion engine and is obtained at the present time based on the sensor values. The operation area may be determined by a method of comparing with a predetermined condition (for example, dividing the operation area into a map).

  In the first embodiment described above, the cylinder 4 is the “partial cylinder” in the first invention, and the cylinders 1, 2 and 3 are the “other cylinders” in the first invention. The EGR passage 50 is the “EGR passage” in the first invention, the exhaust branch pipe 30 is the “first exhaust passage” in the first invention, and the exhaust branch pipe 32 is the “EGR passage” in the first invention. A portion 32a of the exhaust branch pipe 32 is located in the “second exhaust passage”, and a merging position of the main exhaust passage 34 and the exhaust branch pipe 30 is located in the “third exhaust passage” in the first invention. In the “first position” in the invention, the joining position of the main exhaust passage 34 and the exhaust branch pipe 32 is in the “second position” in the first invention, and the turbocharger 40 is in the first invention. The turbine 44 is connected to the “turbulator” in the first aspect of the present invention. The exhaust valve group Ex1 is the “first exhaust valve group” in the first invention, the exhaust valve group Ex2 is the “second exhaust valve group” in the first invention, and the exhaust valves 8a, 8b. The variable valve mechanism for driving the valve corresponds to the “variable valve mechanism” in the first aspect of the present invention.

  In the first embodiment, the ECU 60 realizes the control operations (1-1) to (1-4) according to each operation region. However, the present invention is not limited to this. Instead of applying all the control operations (1-1) to (1-4), one or more control operations are selected from the control operations (1-1) to (1-4). The ECU 60 can be appropriately executed.

  In the first embodiment described above, the ECU 60 corresponds to the “control means” in any one of the second to fifth inventions. Further, in the first embodiment described above, the ECU 60 performs (1-1) to (1-4) operation area storage (map storage), operation area specification, and control operations corresponding thereto, respectively. By executing, the “storage means”, “operation area specifying means”, and “control means” in the tenth aspect of the present invention are realized.

Embodiment 2. FIG.
[Configuration of Internal Combustion Engine According to Second Embodiment]
FIG. 8 is a diagram showing the configuration of the internal combustion engine according to the second embodiment of the present invention. The configuration of the internal combustion engine according to the second embodiment is the same as that of the first embodiment except that exhaust branch pipes 130 and 132 are provided instead of the exhaust branch pipes 30 and 32. Hereinafter, in order to avoid duplication, the same reference numerals are given to the same or corresponding components as those described in the first embodiment, and the description will be omitted or simplified as appropriate.

  The exhaust branch pipe 130 communicates with an exhaust port provided with an exhaust valve 8a in the cylinder 4 through a part 130a. Further, unlike the exhaust branch pipe 130 of the first embodiment, the exhaust branch pipe 132 communicates with only three cylinders 1, 2 and 3.

  In the case of the second embodiment, the exhaust valve 8a in the cylinder 4 belongs to the exhaust valve group Ex1. This is because the exhaust port provided with the exhaust valve 8 a in the cylinder 4 communicates with the upstream position of the turbine 44 through a part 130 a of the exhaust branch pipe 130. Further, the exhaust valve 8b in the cylinder 4 belongs to the exhaust valve group Ex2. The belonging relationship of the exhaust valves 8a and 8b of the cylinder 4 according to the second embodiment to the respective exhaust valve groups is exactly opposite to the belonging relationship in the case of the first embodiment.

[Operation of Internal Combustion Engine According to Second Embodiment]
In the second embodiment, as described below, the valve opening characteristics of the exhaust valve group Ex1 and the exhaust valve group Ex2 are switched according to the operation region.

(2-1) Region of Low Rotation, Exhaust Pressure ≦ Supercharging Pressure FIG. 9 shows the valve opening characteristics in the region of low rotation, exhaust pressure ≦ supercharging pressure in the internal combustion engine according to the second embodiment of the present invention. FIG. In this region, the variable valve mechanism is controlled so as to satisfy the following conditions (5a) and (5b).
(5a) Working angle of the exhaust valve group Ex1> Working angle of the exhaust valve group Ex2 (5b) The valve opening timing of the exhaust valve group Ex1 is made earlier than the valve opening timing of the exhaust valve group Ex2.
As a result, with respect to the exhaust valve group Ex1, exhaust interference avoidance (new air amount increase) due to the blowdown wave of the next cylinder is achieved, and exhaust gases of four cylinders are supplied upstream of the turbine 44, compared with the first embodiment. The supercharging performance can be improved. Further, regarding the exhaust valve group Ex2, the cylinder 4 from which the EGR gas is taken out can be reliably opened only during its own cylinder blowdown, and the backflow of the intake air can be prevented (suppressed).

(2-2) Region where Low Rotation, Exhaust Pressure> Intake Pressure (Supercharging Pressure) FIG. 10 shows low rotation, exhaust pressure> intake pressure (supercharging pressure) in the internal combustion engine according to the second embodiment of the present invention. It is a figure which shows the valve opening characteristic in the area | region which becomes (). In this region, the variable valve mechanism is controlled so as to satisfy the following conditions (6a) and (6b).
(6a) Working angle of the exhaust valve group Ex2> Working angle of the exhaust valve group Ex1 (6b) The valve opening timing of the exhaust valve group Ex1 is made earlier than the valve opening timing of the exhaust valve group Ex2.
Thereby, regarding the exhaust valve group Ex1, it is possible to avoid exhaust interference (increase in fresh air amount) due to the next cylinder blowdown wave. Further, with respect to the exhaust valve group Ex2, it is possible to ensure both the EGR amount and the turbine rotational energy for the cylinder 4 from which EGR gas is extracted.

(2-3) Medium / High Rotation, Region where Exhaust Pressure ≧ Intake Pressure (Supercharging Pressure) FIG. 11 shows medium / high rotation, exhaust pressure ≧ intake pressure (supercharging pressure) in the internal combustion engine according to the second embodiment of the present invention. It is a figure which shows the valve opening characteristic in the area | region which becomes (). In this region, the variable valve mechanism is controlled so as to satisfy the following conditions (7a) and (7b).
(7a) Working angle of exhaust valve group Ex1 = Working angle of exhaust valve group Ex2 (7b) The opening timing of the exhaust valve group Ex1 is made earlier than the opening timing of the exhaust valve group Ex2.
Thereby, turbine rotational energy can be secured for the exhaust valve group Ex1. Further, regarding the exhaust valve group Ex2, with respect to the cylinder 4 for taking out EGR gas, it is possible to secure the EGR gas amount and lower the exhaust gas temperature by reducing the turbine front back pressure.

(2-4) Medium / High Rotation, Exhaust Pressure >> Supercharging Pressure (Exhaust Pressure is Very Larger than Supercharging Pressure) FIG. 12 shows medium / high rotation in the internal combustion engine according to the second embodiment of the present invention. FIG. 5 is a diagram showing valve opening characteristics in a region that becomes an exhaust pressure >> region that becomes a supercharging pressure. In this region, the variable valve mechanism is controlled so as to satisfy the following conditions (8a) and (8b).
(8a) Working angle of the exhaust valve group Ex1> Working angle of the exhaust valve group Ex2 (8b) The opening timing of the exhaust valve group Ex1 is made earlier than the opening timing of the exhaust valve group Ex2.
With regard to the exhaust valve group Ex1, since the amount of exhaust gas is large, exhaust loss at the time of the own cylinder blow-down can be improved, and the residual gas amount can be suppressed. Further, with respect to the exhaust valve group Ex2, the turbine front back pressure can be reduced. For the cylinder 4 for taking out the EGR gas, the EGR gas amount may be excessive during the blowdown, so the exhaust valve 8b that opens and closes the EGR passage 50 according to the valve opening characteristics of the exhaust valve group Ex2 is operated. Is good.
In addition, when specifying the region where the exhaust pressure >> the supercharging pressure (the exhaust pressure is much larger than the supercharging pressure), for example, the exhaust pressure is larger than the supercharging pressure by a predetermined threshold value or more. A determination process for determining whether or not the ECU 60 may be executed.

  In the second embodiment, the ECU 60 controls the variable valve mechanism so as to satisfy the above-mentioned conditions determined for each region according to each operation region described above. As described in the first embodiment, the identification of which of the above operation areas (2-1) to (2-4) corresponds to the current operation area corresponds to various sensor values of the internal combustion engine. On the basis of this, the current operation region obtained based on the sensor value may be compared with a predetermined condition (for example, the operation region is partitioned and mapped).

  In the second embodiment described above, the cylinder 4 is the “partial cylinder” in the first invention, and the cylinders 1, 2 and 3 are the “other cylinders” in the first invention. The exhaust branch pipe 130 is the “first exhaust passage” in the first invention, the exhaust branch pipe 132 is the “second exhaust passage” in the first invention, and a part 130 a of the exhaust branch pipe 130 is In the “third exhaust passage” in the first aspect of the invention, the joining position of the main exhaust passage 34 and the exhaust branch pipe 130 is in the “first position” in the first aspect of the invention. The joining position with the pipe 132 corresponds to the “second position” in the first invention.

  In the second embodiment, the ECU 60 realizes the control operations (2-1) to (2-4) according to each operation region. However, the present invention is not limited to this. Instead of applying all the control operations (2-1) to (2-4), one or more control operations are selected from the control operations (2-1) to (2-4). The ECU 60 can be appropriately executed.

  In the second embodiment described above, the ECU 60 corresponds to the “control means” in any one of the sixth to ninth inventions. In the second embodiment described above, the ECU 60 performs (2-1) to (2-4) operation area storage (map storage), operation area specification, and control operations corresponding thereto. By executing, the “storage means”, “operation area specifying means”, and “control means” in the tenth aspect of the present invention are realized.

1, 2, 3, 4 Cylinders 8a, 8b Exhaust valve 10 Cylinder head 20 Surge tank 22 Throttle 24 Intercooler 26 Intake passage 28 Air cleaner 30 Exhaust branch pipe 32 Exhaust branch pipe 32a Exhaust branch pipe part 34 Main exhaust passage 36 Start Catalyst 40 Turbocharger 42 Compressor 44 Turbine 50 EGR passage 52 EGR cooler 130 Exhaust branch pipe 130a Exhaust branch pipe part 132 Exhaust branch pipe Ex1, Ex2 Exhaust valve group

Claims (10)

A plurality of cylinders each having two or more exhaust ports;
An EGR passage communicating with some exhaust ports of the two or more exhaust ports in some cylinders of the plurality of cylinders;
A first exhaust passage communicating with a part of the two or more exhaust ports in each of the cylinders other than the part of the plurality of cylinders;
A second exhaust passage communicating with another exhaust port other than the partial exhaust port communicating with the first exhaust passage in each of the other cylinders of the plurality of cylinders;
A main exhaust passage communicating with the first exhaust passage at a first position and communicating with the second exhaust passage at a second position different from the first position;
A supercharger having a turbine provided at a position downstream of the first position and upstream of the second position in the main exhaust passage;
The some cylinders of the plurality of cylinders communicate with other exhaust ports other than the some exhaust ports communicating with the EGR passage, and are connected to the main exhaust passage at an upstream position or a downstream position of the turbine. A third exhaust passage in communication;
An exhaust valve provided in each of the two or more exhaust ports of the plurality of cylinders;
A group of exhaust valves that opens and closes an exhaust port that communicates with an upstream position of the turbine is a first exhaust valve group, and a group of exhaust valves that opens and closes an exhaust port that communicates with a downstream position of the turbine is a second exhaust valve group, When the third exhaust passage communicates with the main exhaust passage at the turbine downstream position, an exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group. When the three exhaust passages communicate with the main exhaust passage at the turbine upstream position, the exhaust valve for opening and closing the exhaust port communicating with the EGR passage belongs to the second exhaust valve group. A relative relationship between an opening characteristic of an exhaust valve belonging to one exhaust valve group and an opening characteristic of an exhaust valve belonging to the second exhaust valve group is equal among the plurality of cylinders; Belongs to 1 exhaust valve group And opening characteristics of the exhaust valve opening characteristics and exhaust valves belonging to the second exhaust valve group and the variable valve means can be different that,
An internal combustion engine comprising: The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
In the catalyst warm-up operation of the internal combustion engine, an operating angle condition for making the operating angle of the second exhaust valve group larger than the operating angle of the first exhaust valve group and the opening timing of the second exhaust valve group 2. The internal combustion engine according to claim 1, further comprising control means for controlling the variable valve means so as to establish a valve opening timing condition that is earlier than a valve opening timing of the first exhaust valve group. The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
An operating angle condition for making the operating angle of the first exhaust valve group larger than the operating angle of the second exhaust valve group when the operating range of the internal combustion engine corresponds to a predetermined low speed range, and the first exhaust valve group 2. A control means for controlling the variable valve means so as to establish a valve opening timing condition for making the valve opening timing earlier than the valve opening timing of the second exhaust valve group. 2. The internal combustion engine according to 2. The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
When the operating range of the internal combustion engine is a predetermined medium speed range or a high speed range, and the exhaust pressure corresponds to a predetermined range greater than the intake pressure, the operating angle of the first exhaust valve group is set to that of the second exhaust valve group. The variable valve operating means so as to satisfy an operating angle condition for making the operating angle larger than an operating angle and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group. The internal combustion engine according to any one of claims 1 to 3, further comprising control means for controlling the engine. The third exhaust passage communicates with the main exhaust passage at a downstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the first exhaust valve group;
The operating angle of the first exhaust valve group is set to the second exhaust valve group when the operating range of the internal combustion engine corresponds to a predetermined medium speed range or a high speed range and the exhaust pressure is equal to or higher than the intake pressure. The variable valve operating means so as to establish an operating angle condition that is larger than an operating angle of the first exhaust valve group, and a valve opening timing condition that matches the valve opening timing of the first exhaust valve group and the valve opening timing of the second exhaust valve group. The internal combustion engine according to claim 1, further comprising a control unit that controls the engine. The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
The operating angle of the first exhaust valve group is set to the operating angle of the second exhaust valve group when the operating range of the internal combustion engine corresponds to a predetermined range where the exhaust pressure is equal to or lower than the intake pressure. The variable valve operating means is controlled so as to satisfy a larger operating angle condition and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group The internal combustion engine according to claim 1, further comprising a control unit that performs the control. The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
When the operating region of the internal combustion engine is a predetermined low rotation region and the exhaust pressure corresponds to a predetermined region greater than the intake pressure, the operating angle of the second exhaust valve group is set to be larger than the operating angle of the first exhaust valve group. The variable valve operating means is controlled so as to satisfy a larger operating angle condition and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group. The internal combustion engine according to claim 1, further comprising a control unit. The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
The operating angle of the first exhaust valve group and the second exhaust valve when the operating region of the internal combustion engine corresponds to a predetermined region where the exhaust pressure is equal to or higher than the intake pressure when the operating region is a predetermined middle rotational region or high rotational region. The variable motion so as to satisfy an operating angle condition for matching the operating angle of the group and a valve opening timing condition for making the valve opening timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group. 8. The internal combustion engine according to claim 1, further comprising control means for controlling the valve means. The third exhaust passage communicates with the main exhaust passage at an upstream position of the turbine;
An exhaust valve that opens and closes an exhaust port communicating with the EGR passage belongs to the second exhaust valve group;
When the operating region of the internal combustion engine is in a predetermined middle rotational region or high rotational region and the exhaust pressure is in a predetermined region that is larger than a supercharging pressure by a predetermined amount or more, the operating angle of the first exhaust valve group is set to the first (2) An operating angle condition for increasing the operating angle of the exhaust valve group and a valve opening timing condition for opening the valve timing of the first exhaust valve group earlier than the valve opening timing of the second exhaust valve group are established. The internal combustion engine according to any one of claims 1, 6, 7 and 8, further comprising a control means for controlling the variable valve means. Storage means for storing information defining a relative relationship of the valve opening characteristics between the first exhaust valve group and the second exhaust valve group in accordance with an operating region of the internal combustion engine;
An operation region specifying means for specifying which of the operation regions in the information corresponds to the operation region of the internal combustion engine;
In order to establish the relative relationship of the valve opening characteristics determined by the information according to the operation region specified by the operation region specifying means between the first exhaust valve group and the second exhaust valve group, Control means for controlling the variable valve means;
The internal combustion engine according to claim 1, further comprising:

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