JP2012062882A - Intake and exhaust system for internal combustion engine, operating method of the system, and internal combustion engine equipped with the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the amount of exhaust components when a fuel amount is increased.SOLUTION: An intake and exhaust system (1) for internal combustion engine has exhaust gas recirculation systems (11, 12) including reflux ducts (16, 17) that reflux exhaust gas into intake. The reflux ducts (16, 17) are connected to a supply duct (31) so that an exhaust gas unification opening (18) is formed in the region downstream from a new air inlet port (35) in the supply duct (31). The intake and exhaust system (1) for internal combustion engine is provided to the supply duct (31) between the new air inlet port (35) and exhaust gas joining port, while being equipped with a variable throttle (22) that opens/closes a new air flow (new air passage) (9). When operating with fuel amount being lower than a prescribed value, an annular flow of gas is formed which introduces almost no new air (27). The annular flow of gas is passed into only the exhaust gas recirculation system (11) wherein filtered exhaust gas and/or low pressure exhaust gas (25) reflux.

Description

  The present invention relates to an intake / exhaust system for an internal combustion engine that guides intake and exhaust of the internal combustion engine.

  It is known to provide an internal combustion engine with an intake guidance system for guiding intake air from a fresh air inlet to an engine inlet (intake port). In such a case, the intake air is introduced into the combustion chamber of the internal combustion engine by pressure and burned together with the fuel added in the combustion chamber. Thereby, exhaust gas is generated. The exhaust is led from the combustion chamber through the engine outlet (exhaust port) and through a system for guiding the exhaust to the exhaust outlet or outlet. Further, a system having an exhaust gas recirculation device and a function for returning exhaust gas from the exhaust side of the internal combustion engine to the supply side and mixing exhaust gas into the intake air is known. Such a system is called an exhaust gas recirculation device or an exhaust gas recirculation device.

  Conventionally known intake / exhaust systems have an excess of oxygen-rich gas in the operating state of an internal combustion engine where a very small amount of fuel is burned in the combustion chamber along with the excess oxygen supplied. In other words, there is a problem that oxygen is filled with an excessive amount of gas. In such an operating state, the amount of oxygen contained in the intake air is slightly reduced in the combustion chamber. During this operating state, the amount of oxygen on the supply side and the discharge side increases strongly, and the exhaust gas recirculation (EGR) device is also filled with high oxygen concentration gas.

  In switching from such an operation state in which there is almost no fuel to an operation state in which a large amount of fuel is burned in the combustion chamber, intake air with a relatively high oxygen amount, for example, intake air that contains only fresh air, Introduced into the combustion chamber. Therefore, after switching from an operation state of lean fuel combustion or fuelless combustion to an operation state in which a large amount of fuel is combusted, a high concentration exhaust gas, particularly an exhaust gas containing a high concentration of nitrogen oxide (NOx), is in a long period. Generated across.

  The production of nitrogen oxides mainly depends on the level of oxygen in the intake air. As the amount of oxygen increases, more nitrogen oxides are generated in the combustion process in the combustion chamber. Therefore, in the conventional system, when switching from the no-load operation or the non-running operation to the load operation or the running operation, a temporary excessive increase in the amount of emission components, particularly the emission amount of nitrogen oxides, occurs.

  An object of the present invention is to provide an intake / exhaust system for an internal combustion engine that can suppress exhaust components in switching from an operation state due to combustion of a small amount of fuel to an operation state due to combustion of a larger amount of fuel.

  An object of the present invention is to provide an operation method of an intake / exhaust system for an internal combustion engine that can suppress exhaust components in switching from an operation state due to combustion of a small amount of fuel to an operation state due to combustion of a larger amount of fuel. is there.

  An object of the present invention is to provide an internal combustion engine including an intake / exhaust system for an internal combustion engine that can suppress exhaust components in switching from an operation state caused by combustion of a small amount of fuel to an operation state caused by combustion of a larger amount of fuel. It is in.

  The present invention employs the following technical means to achieve the above object.

  According to the first aspect of the present invention, there is provided a supply duct (31) provided on a supply side (29) for supplying intake air to a combustion chamber (2) of an internal combustion engine (1), and an internal combustion engine (1). In an intake / exhaust system for an internal combustion engine, which includes an exhaust duct (32) provided on an exhaust side (30) for exhaust exhaust with respect to the combustion chamber (2) of the internal combustion engine and guides intake air and exhaust gas in the internal combustion engine The exhaust gas recirculation system (11, 12) includes at least one exhaust gas recirculation system (11, 12). The exhaust gas recirculation system (11, 12) can recirculate exhaust gas from the discharge side (30) to the supply side (29). A recirculation duct (16, 17) connected to the supply duct so as to form an exhaust junction (18) in a region after the fresh air inlet (35) is provided, and the fresh air inlet (35) and the exhaust junction (18) are provided. ) To the supply duct (31) Characterized in that it comprises a variable throttle (22) for opening and closing the fresh air passage (9).

  The invention according to claim 2 is characterized in that the variable throttle (22) is configured to adjust the flow rate of fresh air flowing through the fresh air inlet (35).

  According to a third aspect of the present invention, the variable throttle (22) is configured so that the amount of fuel (QFIN) burned in the combustion chamber (2) per stroke is minimal or equal to zero. It is characterized in that it can be closed in the operating state.

  The invention described in claim 4 further includes a compressor (5) provided on the supply side (29) and / or a turbine (6) provided on the discharge side.

  The invention described in claim 5 further includes an intercooler (7) on the supply side.

  The invention described in claim 6 further includes a particulate filter (8) on the discharge side.

  The invention described in claim 7 further includes a first exhaust gas recirculation system (11) and a second exhaust gas recirculation system (12).

  In the invention according to claim 8, the first exhaust gas recirculation system (11) is configured to recirculate the low pressure exhaust gas (25), and the second exhaust gas recirculation system (12) is configured to recirculate the high pressure exhaust gas (26). It is configured.

  According to the ninth aspect of the present invention, the first exhaust gas recirculation system (11) is configured to recirculate the filtered exhaust gas (25), and the second exhaust gas recirculation system (12) recirculates the non-filtered exhaust gas (26). It is comprised as follows.

  The invention described in claim 10 further includes a control device (24) configured to control opening and closing of the variable aperture (22).

  The invention described in claim 11 further includes a control device (24) connected to the internal combustion engine control device or configured in the internal combustion engine control device and controlling the variable throttle (22). It is characterized by.

  The invention described in claim 12 is an internal combustion engine comprising the intake / exhaust system (28) for an internal combustion engine according to any of the preceding claims.

  The invention as set forth in claim 13 is characterized in that the internal combustion engine (1) is a diesel engine.

  The invention described in claim 14 further includes a fuel injector (4) configured to inject fuel into the combustion chamber (2).

  The invention described in claim 15 further includes a common rail system.

  According to a sixteenth aspect of the present invention, in the operating method of the intake and exhaust system for an internal combustion engine according to any one of the preceding claims, the amount of fuel (QFIN) combusted in the combustion chamber (2) per stroke is extremely high. In the operating state of the internal combustion engine (1) that is small or equal to zero, the fresh air passage (9) is throttled or closed by operating the variable throttle (22).

  The invention according to claim 17 is further characterized in that an annular flow passing through the exhaust gas recirculation system (11, 12) is formed between the discharge side (30) and the supply side (29). , The exhaust gas discharged from the engine outlet (34) is guided to the engine inlet (33) and recirculated so that only a small amount of fresh air (27) is introduced or fresh air (27) is not introduced. The flow rate of exhaust gas (25, 26) is adjusted.

  The invention according to claim 18 is characterized in that the annular flow passes only through the exhaust gas recirculation system (11) through which filtered exhaust gas and / or low-pressure exhaust gas (25) recirculates.

  According to the nineteenth aspect of the present invention, in the operating state of the internal combustion engine (1) in which the amount of fuel (QFIN) burned in the combustion chamber (2) is extremely small or increases again from zero, the operation of the variable throttle (22) is performed. To open the fresh air passage (9) or increase the opening.

  The intake / exhaust system for an internal combustion engine according to the present invention has a supply duct on the supply side and a discharge duct on the discharge side. The supply duct extends from the fresh air inlet to the engine inlet and may be composed of multiple parts. The exhaust duct extends from the engine outlet to the exhaust outlet and may be composed of multiple parts.

  In the intake / exhaust system for an internal combustion engine, the gas can flow through the supply duct in the direction from the fresh air inlet to the engine inlet and through the exhaust duct in the direction from the engine outlet to the exhaust outlet. In the following description, terms for indicating the position in the supply duct or the discharge duct, for example, “back”, “front”, “upstream”, “downstream”, etc., refer to the flow direction described above, Defines the position.

  The system has at least one exhaust gas recirculation system. The exhaust gas recirculation system is configured to guide, guide, and flow exhaust gas from the discharge side to the supply side. The exhaust gas recirculation system includes a recirculation duct. The reflux duct is connected at one end to the exhaust duct in the region after the engine outlet and at the other end to the supply duct in the region before the engine inlet. At the connection point between the reflux duct and the supply duct, an exhaust junction for the refluxed exhaust is formed. The recirculated exhaust gas that joins from the exhaust junction is mixed with the gas already in the supply duct. The exhaust junction is located in a region between the fresh air inlet and the engine inlet in the supply duct. An intake / exhaust system for an internal combustion engine according to the present invention has a variable throttle provided between a fresh air inlet and an exhaust merging port in a supply duct. The variable throttle opens and closes a fresh air flow, that is, a fresh air passage.

  With the variable throttle, it is possible to limit the amount of fresh air flowing into the supply duct and, if necessary, reduce the amount of fresh air to zero. Therefore, by controlling the variable throttle and by controlling the flow rate of one or more exhaust gas recirculation systems, the intake air supplied from the engine inlet to the combustion chamber is recirculated from fresh air and similarly to one or two types of recirculation. It is possible to mix from the exhaust gas to any mixing ratio.

  In particular, when the variable throttle is closed, the intake air supplied from the engine inlet can include only one type of recirculated exhaust gas or only multiple types of recirculated exhaust gas. Thus, during the operation state of the internal combustion engine in which only a very small amount of fuel is burned in the combustion chamber, in the intake and exhaust system for the internal combustion engine, most of the exhaust or all of the exhaust is supplied from the exhaust side to the supply side. This has the advantageous effect of forming an annular flow that is continuously refluxed. As a result, the amount of oxygen in the intake air supplied at the engine inlet is kept low over a long period of time even in an operating state where there is almost no fuel combustion. As a result, the intake / exhaust system for the internal combustion engine does not have excessive fresh air. Similarly, in a change from an unloaded or non-running operating state to an operating state in which a large amount of fuel is combusted again in the combustion chamber, intake air with a small amount of oxygen maintains a low exhaust component, particularly nitrogen oxides. The combustion chamber instantaneously burns during the combustion process so as to keep (NOx) emissions low.

  An operating condition with little combustion of fuel may be the case where only a small amount of added fuel is burned over multiple piston strokes in the combustion chamber of the internal combustion engine, or multiple times in the combustion chamber of the internal combustion engine. Means that no fuel is burned over the piston stroke. The fuel can be added by any known configuration and technique.

  According to an example of an intake and exhaust system for an internal combustion engine according to the present invention, in a direct injection common rail type diesel engine of a vehicle operated with a general driving pattern in traffic, the emission component is suppressed by 3% to 4%, and / or Nitrogen oxide emissions can be reduced. Suppression of exhaust components and nitrogen oxides may appear as a more significant difference in the operating characteristics of the internal combustion engine where frequent changes between the above operating conditions occur.

  The variable throttle can be configured to adjust the flow rate of fresh air entering through the fresh air inlet. This has the advantageous effect of a more precise and faster adjustment of the inhalation composition. In particular, it is possible to generate a mixed composition of intake air with a small proportion of fresh air. This can have an advantageous effect on the stability of combustion of the internal combustion engine and the smooth rotation of the internal combustion engine, and similarly can assist in the control accuracy of the internal combustion engine. This has an advantageous effect on the responsiveness of the internal combustion engine and contributes to quickly obtaining the output of the internal combustion engine corresponding to the demand.

  An intake / exhaust system for an internal combustion engine may comprise a compressor on the supply side and / or a turbine on the exhaust side. For example, a supercharger having a compressor on the supply side can be provided. As an example of a supercharger, a turbocharger can be provided. As a result, the intake air supplied to the engine inlet can be pressurized, and therefore the amount of intake air per stroke introduced into the combustion chamber can be increased. The amount of energy stored in the exhaust pressure that is increased after combustion is absorbed and utilized by the turbine. Therefore, it is possible to generate high output from the internal combustion engine even when the amount of oxygen in the intake air is small, such as when the internal combustion engine is operated with less exhaust components and less nitrogen oxides, and particularly efficiently. .

  The intake / exhaust system for an internal combustion engine throttles the fresh air passage by operating the variable throttle when the amount of fuel burned in the combustion chamber per stroke is minimal or when the internal combustion engine is in an operating state equal to zero. Or it may be operated by a method of increasing the flow rate of the recirculated exhaust gas with closing. As a result, the amount of oxygen in the intake air can be kept low for a long period of time even in the operating state of the internal combustion engine where the combustion of fuel is low. In particular, even in such operating conditions, it is possible to adjust the amount of oxygen in the intake air to a desired amount, or to match the amount of oxygen in the intake air to the desired amount, if necessary.

  An annular flow that passes through the exhaust gas recirculation system between the discharge side and the supply side, and the exhaust exhausted from the engine outlet is guided to the engine inlet, so that only a small amount of fresh air is introduced or no fresh air is introduced As a result, an advantageous effect that the flow rate of the recirculated exhaust gas is adjusted is produced. Thereby, in particular, the recirculated exhaust gas having a small amount of oxygen flows through the duct of the exhaust gas recirculation system. Thus, a particularly fast adjustment of the intake air mixing ratio can be achieved even in a change in operating conditions.

  Furthermore, an advantageous effect is obtained that an annular flow is formed only in the exhaust gas recirculation system in which filtered exhaust gas and / or low pressure exhaust gas is recirculated. In this configuration, the amount of exhaust and / or exhaust and particulate components in the combustion chamber can be kept low, so that the machine of the parts arranged in the region of the combustion chamber, such as a fuel injector, for example. Stress and chemical stress can be kept low.

  One object of the present invention is an internal combustion engine in which the amount of oxygen in intake air can be adjusted by the above-described method when the amount of fuel burned in the combustion chamber is minimal or equal to zero. It is to provide an intake and exhaust system. The intake / exhaust system for an internal combustion engine of the present invention can be applied to a diesel engine.

  Note that the reference numerals in parentheses described in the claims and the above-described means indicate the correspondence with the specific means described in the embodiments described later as one aspect, and are technical terms of the present invention. It does not limit the range.

1 is a block diagram of an intake / exhaust system for an internal combustion engine according to a first embodiment to which the present invention is applied. It is a block diagram which shows the flow of the gas in the intake / exhaust system for internal combustion engines which concerns on 1st Embodiment. It is a block diagram which shows the flow of the gas in the intake / exhaust system for internal combustion engines which concerns on 1st Embodiment, Comprising: The driving | running state of the internal combustion engine in combustion without a fuel or combustion with little fuel is shown. It is a graph which shows the action | operation of the intake / exhaust system for internal combustion engines which concerns on 1st Embodiment, and the action | operation of a comparative example.

  Note that the reference numerals in parentheses described in the claims and the above-described means indicate the correspondence with the specific means described in the embodiments described later as one aspect, and are technical terms of the present invention. It does not limit the range.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly show that combinations are possible in each embodiment, but also combinations of the embodiments even if they are not explicitly stated unless there is a problem with the combination. Is also possible.

(First embodiment)
This embodiment relates to an intake / exhaust system 28 in the internal combustion engine 1. FIG. 1 shows an intake / exhaust system 28 for an internal combustion engine according to this embodiment. As a representative of the internal combustion engine 1, a cylinder having a piston 23 that compresses a gas placed in the combustion chamber 2 is illustrated. The internal combustion engine 1 can include an arbitrary number of cylinders. The internal combustion engine 1 is, for example, a multi-cylinder internal combustion engine such as a 4-cylinder, a 6-cylinder, or an 8-cylinder. Of course, other numbers of cylinders may be employed. The internal combustion engine 1 is a diesel engine, and includes a common rail system as a direct injection fuel supply device.

  Intake is introduced into the combustion chamber 2 from the engine inlet 33 through the valve 3. The internal combustion engine 1 is, for example, a direct injection internal combustion engine. The internal combustion engine 1 includes a fuel injector 4 for spraying fuel directly into the combustion chamber 2. The gas in the combustion chamber 2 is led from the engine outlet 34 to the discharge side 30 through the valve 3 '. An intake / exhaust system 28 for an internal combustion engine has a supply duct 31 and a supply side 29 for supplying intake air, and a discharge duct 32 for discharging exhaust gas with reference to the combustion chamber 2 of the internal combustion engine 1. Side 30.

  The term “intake” should be understood as a gas introduced into the combustion chamber 2 of the internal combustion engine 1 through the engine inlet 33. Thus, the intake air may be a mixture of several components. These components include fresh air 27 introduced from the fresh air inlet 35 and / or one or more types of refluxed exhaust 25,26. Thus, the term “intake” refers to the gas in the supply duct 31 and more specifically refers to the gas at the engine inlet 33 or the gas in the combustion chamber 2 prior to the combustion stroke. The term “exhaust” is to be understood as a gas exhausted from the combustion chamber 2 through the engine outlet 34. The term “exhaust” refers to the gas in the exhaust duct 32 and / or the gas in the reflux ducts 16, 17. For better distinction, the exhaust in the reflux ducts 16, 17 is called the refluxed exhaust 25, 26. The exhaust 25 is also called the low pressure exhaust 25 or the filtered exhaust 25. The exhaust 26 is also referred to as the high pressure exhaust 25 or the non-filtered exhaust 26.

  The internal combustion engine intake / exhaust system 28 includes at least one exhaust gas recirculation system 11, 12. One exhaust gas recirculation system 11, 12 includes recirculation ducts 16, 17. The exhaust gas recirculation systems 11 and 12 are also called EGR. In FIG. 1, an intake / exhaust system 28 for an internal combustion engine including two exhaust gas recirculation systems 11 and 12 is shown. However, the intake and exhaust system 28 for the internal combustion engine can be configured to include only one or other number of exhaust gas recirculation systems.

  The supply duct 31 can be constituted by, for example, a pipe that can be further divided. The supply duct 31 can be divided into a plurality of sections as required. The supply duct 31 is configured to be suitable for guiding and guiding the intake air from the fresh air inlet 35 to the engine inlet 33. On the path of the supply duct 31 between the fresh air inlet 35 and the engine inlet 33, other components and connecting portions with other ducts may be arranged.

  It is desirable that the discharge duct 32 is also constituted by a pipe. The exhaust duct 32 is designed and configured to direct exhaust from the engine outlet 34 to the exhaust outlet 36 or the exhaust system. From the exhaust outlet 36, the exhaust stream 10 is discharged into the atmosphere. In the discharge duct 32, another component and a connection part with another duct may be provided. The supply duct 31 and the discharge duct 32 may alternatively or additionally adopt other configurations in whole or in part. For example, a hose or a deformable duct can be employed. Each of supply duct 31 and discharge duct 32 may be composed of a plurality of parts or portions.

  One exhaust gas recirculation system 11, 12 includes recirculation ducts 16, 17. The recirculation ducts 16 and 17 can recirculate the exhaust gas of the internal combustion engine 1 from the discharge side 30 to the supply side 29, and are configured to guide and guide the exhaust gas. In FIG. 1, for example, the first exhaust gas recirculation system 11 including the recirculation duct 16 connected to the region of the supply duct 31 behind the fresh air inlet 35 is illustrated. An exhaust junction 18 is formed at a connection point between the reflux duct 16 and the supply duct 31.

  The intake / exhaust system 28 for the internal combustion engine preferably includes the compressor 5 on the supply side. The intake / exhaust system 28 for the internal combustion engine includes a turbine 6 on the exhaust side 30 in addition or alternatively, if necessary. The compressor 5 is preferably provided in the region of the supply duct 31 between the exhaust junction 18 and the engine inlet 33. The turbine 6 is provided on the discharge side 30 and is preferably provided in the region between the engine outlet 34 and the exhaust outlet 36. The compressor 5 serves to pressurize the intake air. The turbine 6 serves to depressurize the exhaust with pressure and thereby serves to absorb energy stored in the exhaust pressure. The turbine 6 is preferably a variable turbine. The variable turbine can adjust the degree of exhaust pressure reduction and / or the degree of energy transmission by making the collision angle of the turbine rotor blade variable. The compressor 5 and the turbine 6 may be linked together by a mechanical shaft. Alternatively, the compressor 5 and the turbine 6 may be configured to operate mechanically independently from each other. For example, the compressor 5 is alternatively or additionally provided with another individual driving power source. For example, an electric motor. An intake / exhaust system 28 for an internal combustion engine according to an embodiment of the present invention includes a variable throttle for opening and closing a fresh air flow (fresh air passage) 9 in a supply duct 31 between a fresh air inlet 35 and an exhaust junction 18. 22. The variable diaphragm 22 can take various configurations. For example, the variable throttle 22 can be formed by a butterfly valve, by a slide valve, or by a variable valve. In FIG. 1, the variable throttle 22 is shown as an example of a cantilevered peristaltic valve. Here, the variable throttle 22 is shown in the closed position. Preferably, the variable throttle 22 completely closes the fresh air passage in the closed position. Instead, the variable throttle 22 may allow a very small amount of fresh air inflow at the valve closing position.

  In the embodiment illustrated in FIG. 1, the intake and exhaust system 28 for an internal combustion engine includes a second exhaust gas recirculation system 12 including a recirculation duct 17. The second exhaust gas recirculation system 12 can be provided as an alternative or in addition to the first exhaust gas recirculation system 11. The second exhaust gas recirculation system 12 guides and guides the exhaust gas from the region of the exhaust duct 32 between the engine outlet 34 and the turbine 6 to the supply side 29. The reflux duct 17 is preferably connected to the area of the supply duct 31 on the supply side 29 after the compressor 5 and before the engine inlet 33. As a result, the exhaust gas can be recirculated from the discharge side 30 to the supply side 29 under high pressure using the second exhaust gas recirculation system. The second exhaust gas recirculation system 12 can be provided with an EGR cooler 15 and a bypass 13. The EGR cooler 15 cools the recirculated exhaust gas. Further, a part of the second exhaust gas recirculation system 12 can be designed and configured based on a known technique. The flow rate of the exhaust gas passing through the reflux duct 17 can be adjusted by the control valve 21. An exhaust junction 19 is formed at a connection point between the reflux duct 17 and the supply duct 31.

  The intake / exhaust system 28 for the internal combustion engine can include the intercooler 7. The intercooler 7 is also referred to as an intake air cooler 7 for cooling again the intake air heated in the compressor 5 that is a supercharger. The intercooler 7 is provided in the region of the supply duct 31 on the supply side 29. The intercooler 7 is preferably provided in the region of the supply duct 31 behind the compressor 5 and in front of the exhaust junction 19.

  The intake / exhaust system 28 for the internal combustion engine can further include a particulate filter 8 on the exhaust side 30. The particulate filter 8 filters the exhaust gas. The particulate filter 8 captures the particulate component (particulate component) contained in the exhaust gas, and reduces the particulate component contained in the exhaust gas. The specific structure of such a particulate filter 8 is already known. The particulate filter 8 is provided in the region of the discharge duct 32 on the discharge side 30. In particular, the particulate filter 8 is preferably arranged in the region of the exhaust duct 32 behind the turbine 6 and before the connection point between the reflux duct 16 and the exhaust duct 32. Therefore, the first exhaust gas recirculation system 11 can suitably guide the filtered exhaust gas in the region behind the particulate filter 8 to the supply side 29.

  The first recirculation duct 16 is preferably connected to the region of the exhaust duct 32 behind the turbine 6 so that the first exhaust recirculation system 11 directs the exhaust under low pressure to the supply side 29 and returns it. . As shown in the figure, the recirculation duct 16 of the first exhaust recirculation system 11 is connected in more detail to the area of the exhaust duct 32 behind the turbine 6 and behind the particulate filter 8. . In this case, the first exhaust gas recirculation system 11 is designed and configured to guide and return filtered exhaust gas under low pressure to the supply side 29. A part of the first exhaust gas recirculation system 11 can be designed and configured based on a known technique. The first exhaust gas recirculation system 11 can preferably include an EGR cooler 14 for cooling the recirculated exhaust gas 25 in the region of the recirculation duct 16. The EGR cooler 14 cools the recirculated exhaust gas. The first exhaust gas recirculation system 11 can include a control valve 20 for adjusting the flow rate of the exhaust gas flowing through the recirculation duct 16.

  FIG. 2 shows the basic flow of intake and exhaust in this embodiment. On the supply side 29, fresh air 27 is introduced into the supply duct 31 through the fresh air inlet 35. Therefore, a fresh air flow 9 is formed in the area of the fresh air inlet 35. The fresh air flow 9 is formed in a passage through which only fresh air flows. The fresh air flow 9 can also be referred to as a fresh air passage 9. At the exhaust junction 18, the recirculated exhaust gas 25 is further introduced from the recirculation duct 16 into the supply duct 31 and drawn. The exhaust 25 that has been refluxed from the exhaust junction 18 is mixed with fresh air that flows through the supply duct 31. If necessary, the mixed gas is led to the engine inlet 33 through the supply duct 31. The gas is preferably guided through the compressor 8 and the intercooler 7. At the merging port 19 for exhaust, the other exhausted exhaust gas 26 from the second exhaust gas recirculation system 12 is guided to the supply duct 31 and drawn. In the area of the supply duct 31 behind the junction 19 for exhaust, the exhaust 26 introduced from the reflux duct 17 is mixed with the gas supplied from the area of the previous supply duct 31. The mixed gas present at the engine inlet 33 has one or more components, and in particular includes fresh air 27 and one or more types of refluxed exhaust 25,26. .

  The flow rate of the fresh air 27 can be adjusted by the variable throttle 22. The flow rate of the recirculated exhaust gas 25 in the first exhaust gas recirculation system 11 is adjusted by the control valve 20. The flow rate of the recirculated exhaust gas 26 in the second exhaust gas recirculation system 12 is adjusted by the control valve 21. Depending on the two flow rate adjustments described above, the gas present at the engine inlet 33 is only fresh air 27, only the exhaust gas 25 recirculated from the first exhaust gas recirculation system 11, or from the second exhaust gas recirculation system 12. Only the exhaust gas 26 that has been recirculated is obtained. Further, according to the adjustment of the two flow rates described above, the gas present at the engine inlet 33 becomes a mixed gas in which at least two of the three types of gases 27, 25, and 26 are mixed. That is, the gas present at the engine inlet 33 is the fresh air 27 and / or the recirculated exhaust gas 25 from the first exhaust gas recirculation system 11 and / or the recirculated exhaust gas 26 from the second exhaust gas recirculation system 12. It becomes a mixed gas. Depending on the two flow rate adjustments described above, the required mixing components are obtained. The configuration of the gas can be accurately adjusted at an arbitrary ratio by setting each flow rate.

  FIG. 3 shows the flow of gas flowing through the intake / exhaust system 28 for an internal combustion engine in an operating state of the internal combustion engine 1 in which the amount of fuel burned in the combustion chamber 2 per stroke is extremely small or zero. ing. As shown in the drawing, it is desirable that the variable throttle 22 can be closed in the above-described operation state. Thereby, the flow rate of fresh air is adjusted to a very small amount or zero. Therefore, in this system 28, an annular flow of intake and exhaust is formed. In this annular flow, the exhaust discharged from the engine outlet 34 is filtered by the particulate filter 8, then returns to the supply duct 31 through the first exhaust gas recirculation system 11, and then passes through the engine inlet 33. It flows to enter the combustion chamber 2 again. In the case of the illustrated flow, the control valve 21 of the second exhaust gas recirculation system 12 is closed so as not to return the non-filtered exhaust gas 26 from the second exhaust gas recirculation system 12 to the supply duct 31. This has an advantageous effect in terms of mechanical and chemical stresses on the parts arranged in the region of the combustion chamber, for example a fuel injector. However, alternatively or additionally, inflow of non-filtered exhaust 26 may be allowed.

  In the illustrated gas flow, almost exclusively or almost entirely consists of exhaust 25, 26, so that intake air containing a suppressed amount of oxygen is supplied to the combustion chamber 2. Exhaust gas discharged from the combustion chamber 2 in an operation state by combustion with almost no fuel is led to an exhaust duct 32 and further returned to the supply side 19 through one or a plurality of exhaust gas recirculation systems 11 and 12.

  In an operating state by combustion with almost no fuel, the fresh air flow (fresh air passage) 9 is almost completely closed, but a small amount of exhaust gas is discharged from the exhaust duct 32 to the atmosphere through the exhaust outlet 36 or the exhaust outlet. . In such a case, the amount of gas present inside the intake / exhaust system 28 for the internal combustion engine is suppressed. Alternatively, a small amount of fresh air may flow through the variable throttle 22 provided on the supply side 29. This small amount of fresh air provides a constant amount of oxygen during inspiration or a gradual increase in the amount of oxygen that can be controlled during inspiration. This compensates for the partial or complete reduction in the amount of gas caused by the leakage of exhaust from the exhaust outlet 36.

  The intake / exhaust system 28 for the internal combustion engine preferably includes a control device 24 for the variable throttle 22. The control device 24 is an electronic control unit (ECU). The control device 24 is provided by a microcomputer provided with a computer-readable storage medium. The storage medium stores a computer-readable program. The storage medium can be provided by a memory. The program is executed by the control device 24 to cause the control device 24 to function as a device described in this specification, and to cause the control device 24 to function so as to execute the control method described in this specification. The means provided by the control device 24 can also be referred to as a functional block or module that achieves a predetermined function.

  The control device 24 operates the intake / exhaust system 28 for the internal combustion engine by a predetermined operation method. This operation method can also be called a control method. The control device 24 is designed and configured to cause the variable aperture 22 to open or close. The control device 24 is configured to control opening / closing of the variable diaphragm 22. The control device 24 is connected to an internal combustion engine control device (not shown) and receives a command value. The control device 24 calculates a desired flow rate of the fresh air 27 based on the command value.

  The control device 24 opens or closes the variable aperture 22 by activating and controlling the variable aperture 22. The control device 24 is specifically designed and configured to adjust the flow rate of the fresh air 27 in the variable throttle 22 by adjusting the opening of the variable throttle 22 to a predetermined value. Such an opening is set, for example, by an angle in a range between the fully open position and the fully closed position of the cantilevered peristaltic valve. Alternatively, the control device 24 may be configured integrally with the control device for the internal combustion engine. The control device 24 provides control means for controlling the control valve 20, the control valve 21, and the variable throttle 22 in accordance with the operating state of the internal combustion engine 1. The control device 24 opens the control valves 20 and 21 in the first operating state of the internal combustion engine 1 where the fuel amount QFIN burned in the combustion chamber 2 per one stroke is a minimum amount or equal to zero, Complete annular flow control means for closing the variable throttle 22 is provided. The control device 24 opens the control valve 20 in the first operation state of the internal combustion engine 1 in which the fuel amount QFIN burned in the combustion chamber 2 per one stroke is minimal or equal to zero. A complete annular flow control means is provided for closing 21 and closing the variable throttle 22. The control device 24 opens the control valve 20 and / or the control valve 21 in a second operation state different from the first operation state, in which the fuel amount QFIN combusted in the combustion chamber 2 is relatively large. A partial annular flow control means for opening 22;

  In FIG. 4, graphs 4 a, 4 b, 4 c, and 4 d show characteristic values in an example of the operating state of the internal combustion engine 1. In order to facilitate understanding, the traveling internal combustion engine 1 mounted on an automobile is assumed here.

  The uppermost graph 4a shows an increase in the fuel injection amount QFIN per stroke over time t. Graph 4b shows a cumulative value Acc. Indicates NOx. The graph 4c shows the instantaneous value NOx of the nitrogen oxide emission amount at time t. The lowermost graph 4d shows the transition of the running speed of the automobile over time.

  The above four graphs 4a, 4b, 4c, 4d are values that would be obtained under the same physical conditions. The solid curve 50 shows the value that would be obtained by an embodiment to which the present invention is applied. Dashed curve 51 shows the value that would be obtained by the comparative example.

  An example of the operation of the illustrated internal combustion engine can be divided into four sections A, B, C, and D on the time axis. The section A and the section C correspond to the operating state of the internal combustion engine 1 in the no-load operation in which the fuel amount QFIN burned per stroke is a very small amount. As illustrated in the graph 4d, in such a driving state, that is, in the sections A and C, the traveling speed of the automobile gradually decreases.

  In the section B and the section D, the fuel amount QFIN burned per stroke is relatively large, and corresponds to the operating state of the internal combustion engine 1 that is under load operation. As illustrated in the graph 4d, in such an operation state, that is, in the sections B and D, the traveling speed of the automobile is maintained at a constant value, for example. Alternatively, in such a driving state, that is, the sections B and D, acceleration of the automobile may appear.

  By applying the operating direction of the intake / exhaust system 28 for an internal combustion engine according to the embodiment of the present invention, the operating state of the internal combustion engine 1 in which the amount of fuel burned in the combustion chamber 2 per one stroke is minimal or equal to zero. , The fresh air flow (fresh air passage) 9 is throttled or closed by operating the variable throttle 22. Therefore, in the sections A and C of FIG. 4, the fresh air flow (fresh air passage) 9 is closed by operating the variable throttle 22. Therefore, the amount of oxygen in the intake air is kept low throughout the operation state (section A, section C) involving combustion with almost no fuel.

  In the change of the operating state, therefore, in the operating state of the internal combustion engine 1 in which the amount of fuel combusted in the combustion chamber 2 per stroke is increased from the minimum amount or from zero again, the variable throttle 22 is operated. The fresh air passage 9 is reopened or increased. Such a change in the driving state corresponds to the section B and the section D in the figure.

  As is apparent from the graph 4c, the transition 51 of the nitrogen oxide NOx emission amount of the comparative example, which is a known intake / exhaust system, after the change of the operating state, that is, after the change from the section A to the section B, and After the change from the section C to the section D, a remarkable excessive increase (maximum value) is shown. On the contrary, the transition 50 of the nitrogen oxide NOx emission amount of the embodiment of the present invention is the change of the change from the section A to the section B and the change from the section C to the section D after the change of the operation state. Later, it remains substantially low. The two regions hatched in the graph 4c are the nitrogen oxide emission amount 50 of the embodiment of the present invention, the nitrogen oxide emission amount 50 of the embodiment of the present invention, and the nitrogen oxide emission amount 51 of the comparative example. The difference between is shown. The hatched region 52 corresponds to the nitrogen oxide emission suppressed by the embodiment of the present invention after the change in the operating state, that is, the change from the section C to the section D.

  From the graph 4b, the cumulative value Acc. NOx50 is a cumulative value of Acc. Compared with NOx51, it is significantly suppressed. The more frequent the change from an operating state in which little fuel is burned to an operating state in which more fuel is burned, ie, from section A to section B and from section C to section D, the more The amount of nitrogen oxide NOx emission can be reduced. Particulates and other emission components are also considered to be the same as the NOx emission shown in the graph 4c.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. The structure of the said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope. The characteristic configurations of the above embodiments can be arbitrarily combined, can be interchanged with each other, and can be partially omitted. The present invention can be applied to all kinds of internal combustion engines 1 for which application is desired. For example, the present invention can be applied to a gasoline internal combustion engine, a diesel engine, or a gas internal combustion engine. The use of the internal combustion engine 1 is not limited. For example, the internal combustion engine 1 can be a mobile internal combustion engine for ground or water vehicles, or a stationary internal combustion engine for power supply or machine drive.

  The fuel combusted in the combustion chamber 2 can be added by various methods. For example, the fuel can be added by direct injection direct injection into the combustion chamber 2, by injection into the precombustion chamber, or by injection into intake air, for example by a carburetor. The intake / exhaust system 28 for the internal combustion engine may include only one exhaust gas recirculation system, or may include a plurality of exhaust gas recirculation systems 11 and 12. Each exhaust recirculation system can be provided with one or several recirculation ducts 16, 17.

  During the operating state of the internal combustion engine 1 where there is almost no fuel combustion, the annular flow of intake and exhaust formed in the intake / exhaust system 28 for the internal combustion engine is only on the first exhaust gas recirculation system 11, It may appear only on the exhaust gas recirculation system 12 or on some exhaust gas recirculation systems 11, 12. The selection of the exhaust gas recirculation systems 11, 12 can depend on the type of fuel.

  A particularly simple embodiment of the invention is configured such that the internal combustion engine 1 comprises only one exhaust gas recirculation system 11 and the variable throttle 22 still allows a small amount of fresh air flow even in the closed state. . In such an embodiment, the variable throttle 22 can be configured to be set only in the valve open state and the valve closed state. The variable aperture 22 configured in this way is particularly simple in structure and low in price, and can be realized without spending much development effort on the control technology.

  DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 2 Combustion chamber, 3 3 'valve, 4 Fuel injector, 5 Compressor, 6 Turbine, 7 Intercooler, 8 Particulate filter, 9 Fresh air flow (new air passage), 10 Exhaust flow, 11 1st 1 exhaust recirculation system, 12 second exhaust recirculation system, 13 bypass, 14 EGR cooler, 15 EGR cooler, 16 recirculation duct, 17 recirculation duct, 18 exhaust confluence, 19 exhaust confluence, 20 control valve, 21 Control valve, 22 Variable throttle, 23 Piston, 24 Control device, 25 Recirculated exhaust (filtered exhaust or low pressure exhaust), 26 Recirculated exhaust (non-filtered exhaust or high pressure exhaust), 27 Fresh air, 28 Internal combustion Intake / exhaust system for engine, 29 supply side, 30 discharge side, 31 supply duct, 32 discharge duct, 33 engine inlet, 34 engine outlet, 35 Air inlet 36 exhaust outlet, the behavior of the embodiment of the 50 present invention, the behavior of the 51 comparative examples, 52 suppressing amount of NOx.

Claims (19)

A supply duct (31) provided on the supply side (29) for supplying intake air to the combustion chamber (2) of the internal combustion engine (1);
An exhaust duct (32) provided on the exhaust side (30) for exhaust exhaust with respect to the combustion chamber (2) of the internal combustion engine (1),
In the internal combustion engine intake and exhaust system for guiding intake and exhaust in the internal combustion engine,
At least one exhaust gas recirculation system (11, 12),
In the exhaust gas recirculation system (11, 12), exhaust gas can be recirculated from the discharge side (30) to the supply side (29) and in a region after the fresh air inlet (35) in the supply duct (31). A reflux duct (16, 17) connected to the supply duct to form an exhaust junction (18);
A variable throttle (22) provided in the supply duct (31) between the fresh air inlet (35) and the exhaust junction (18) for opening and closing the fresh air passage (9). An intake / exhaust system for an internal combustion engine.   The intake / exhaust system for an internal combustion engine according to claim 1, wherein the variable throttle (22) is configured to adjust a flow rate of fresh air flowing through the fresh air inlet (35).   The variable throttle (22) is closed in the operating state of the internal combustion engine (1) where the amount of fuel (QFIN) burned in the combustion chamber (2) per stroke is minimal or equal to zero. The intake / exhaust system for an internal combustion engine according to claim 1 or 2, characterized in that   The internal combustion engine according to any one of claims 1 to 3, further comprising a compressor (5) provided on the supply side (29) and / or a turbine (6) provided on the discharge side. Intake and exhaust system.   The intake / exhaust system for an internal combustion engine according to any one of claims 1 to 4, further comprising an intercooler (7) on a supply side.   The intake / exhaust system for an internal combustion engine according to any one of claims 1 to 5, further comprising a particulate filter (8) on an exhaust side.   The intake / exhaust system for an internal combustion engine according to any one of claims 1 to 6, further comprising a first exhaust gas recirculation system (11) and a second exhaust gas recirculation system (12).   The first exhaust gas recirculation system (11) is configured to recirculate low pressure exhaust gas (25), and the second exhaust gas recirculation system (12) is configured to recirculate high pressure exhaust gas (26). The intake / exhaust system for an internal combustion engine according to claim 7.   The first exhaust gas recirculation system (11) is configured to recirculate filtered exhaust gas (25), and the second exhaust gas recirculation system (12) is configured to recirculate non-filtered exhaust gas (26). The intake / exhaust system for an internal combustion engine according to claim 7 or 8, wherein   The intake / exhaust system for an internal combustion engine according to any one of claims 1 to 9, further comprising a control device (24) configured to control opening and closing of the variable throttle (22).   The control device (24) further comprising a control device (24) connected to the internal combustion engine control device or configured in the internal combustion engine control device and controlling the variable throttle (22). The intake / exhaust system for an internal combustion engine according to claim 10.   An internal combustion engine comprising the intake / exhaust system (28) for an internal combustion engine according to any one of claims 1 to 11.   13. Internal combustion engine according to claim 12, characterized in that the internal combustion engine (1) is a diesel engine.   The internal combustion engine according to claim 12 or 13, further comprising a fuel injector (4) configured to inject fuel into the combustion chamber (2).   The internal combustion engine according to any one of claims 12 to 14, further comprising a common rail system.   The method for operating an intake / exhaust system for an internal combustion engine according to any one of claims 1 to 11, wherein the amount of fuel (QFIN) burned in the combustion chamber (2) per stroke is extremely small, or An operating method of an intake / exhaust system for an internal combustion engine, characterized in that, in an operating state of the internal combustion engine (1) equal to zero, the fresh air passage (9) is throttled or closed by operating the variable throttle (22).   Further, an annular flow passing through the exhaust gas recirculation system (11, 12) is formed between the discharge side (30) and the supply side (29). ) Is led to the engine inlet (33), so that only a small amount of fresh air (27) is introduced or fresh air (27) is not introduced. The method of operating an intake / exhaust system for an internal combustion engine according to claim 16, wherein the flow rate of   18. The method of operating an intake / exhaust system for an internal combustion engine according to claim 17, wherein the annular flow is passed only through an exhaust gas recirculation system (11) through which filtered exhaust gas and / or low-pressure exhaust gas (25) is recirculated.   In the operating state of the internal combustion engine (1) in which the amount of fuel (QFIN) combusted in the combustion chamber (2) is extremely small or increases again from zero, the fresh air passage ( The method of operating an intake / exhaust system for an internal combustion engine according to any one of claims 16 to 18, wherein 9) is opened or the opening degree is increased.

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