JP4720541B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine including an exhaust gas recirculation device and a pulse supercharging valve.

  An internal combustion engine such as a diesel engine is equipped with an exhaust gas recirculation device (hereinafter simply referred to as an EGR device) in order to reduce NOx (nitrogen oxide). The EGR device takes a part of the exhaust gas into the intake side, thereby lowering the oxygen concentration of the intake air and introducing an inert gas to reduce the combustion temperature and the combustion speed. This reduces the NOx emission. When the exhaust gas is recirculated by driving the EGR device, the pressure difference between the pressure of intake air on the intake passage side (also referred to as intake system pressure) and the pressure of exhaust gas on the exhaust passage side (also referred to as exhaust system pressure) is set. It is important to maintain and ensure that the exhaust gas is recirculated.

  Thus, for example, Patent Document 1 discloses an EGR control device that controls the driving of the EGR valve by setting the target opening of the EGR valve from the differential pressure between the intake system pressure and the exhaust system pressure and the target EGR amount. . According to this EGR device, a desired exhaust reduction effect can be obtained.

  By the way, a technique for controlling an intake air flow by arranging an on-off valve for pulse supercharging (hereinafter referred to as a pulse supercharging valve) in the middle of an intake passage is known (see, for example, Patent Document 2). The pulse supercharging valve is arranged on the upstream side of the intake valve (intake valve), and is closed in the intake stroke in which the intake valve is opened and the piston is lowered, and negative pressure is generated downstream of the intake stroke. Then, by opening the pulse supercharging valve in the presence of this negative pressure, the air downstream from the pulse supercharging valve is accelerated and rushed into the cylinder to increase the air filling amount.

Japanese Patent No. 3493986 JP 2000-248946 A

  By applying the pulse supercharging valve to the EGR device of Patent Document 1 described above, it is expected that the internal combustion engine has an improved output while improving the emission. However, when pulse supercharging is performed, the intake system pressure changes suddenly. If the intake system pressure changes during the execution of EGR, the amount of EGR gas to be recirculated changes and the designed EGR rate fluctuates. Since the EGR control device of Patent Document 1 does not consider the sudden change in the intake system pressure, there is a concern that the EGR becomes inappropriate when a pulse supercharging valve is applied.

  Accordingly, an object of the present invention is to provide an internal combustion engine that can properly execute exhaust gas recirculation (EGR) even when pulse supercharging is performed.

The above object is an internal combustion engine comprising an exhaust gas recirculation device that recirculates part of the exhaust gas in the exhaust passage to the intake passage, and a pulse supercharging valve that opens and closes the intake passage. Fluctuation suppression means that suppresses fluctuations in the exhaust gas recirculation rate that occurs when the pulse supercharging is performed by operating the pulse supercharging valve during driving of the recirculation device and performing the pulse supercharging , and The fluctuation suppressing means is achieved by an internal combustion engine that suppresses the fluctuation by correcting an opening of a flow control valve provided in the exhaust gas recirculation device .

  According to the present invention, since the fluctuation suppressing means suppresses fluctuations in the exhaust gas recirculation rate caused by the execution of pulse supercharging, it is possible to provide an internal combustion engine that can execute EGR properly even when pulse supercharging is performed.

Another object of the present invention is an internal combustion engine comprising an exhaust gas recirculation device that recirculates a part of the exhaust gas in the exhaust passage to the intake passage, and a pulse supercharging valve that opens and closes the intake passage. Fluctuation suppression means that suppresses fluctuations in the exhaust gas recirculation rate caused by the execution of pulse supercharging when the pulse supercharging valve is operated during operation of the gas recirculation device to perform pulse supercharging, the pulse of the first exhaust gas recirculation device and the intake passage in which the exhaust gas recirculation system connects the upstream side of the gas purification catalyst of the exhaust passage and downstream of the pulse supercharging valve of the intake passage Including a second exhaust gas recirculation device that connects an upstream side of a supercharging valve and a downstream side of the purification catalyst of the exhaust passage, and the fluctuation suppressing means performs the pulse supercharging, The exhaust gas recirculation device Suppressing the variation by changing the serial first exhaust gas recirculation device to the second exhaust gas recirculation system, it is achieved by an internal combustion engine. Also in the present invention, since the fluctuation suppressing means suppresses fluctuations in the exhaust gas recirculation rate caused by the execution of pulse supercharging, it is possible to provide an internal combustion engine that can properly execute EGR even when pulse supercharging is performed.

Another object of the present invention is an internal combustion engine comprising an exhaust gas recirculation device that recirculates a part of the exhaust gas in the exhaust passage to the intake passage, and a pulse supercharging valve that opens and closes the intake passage. Fluctuation suppression means that suppresses fluctuations in the exhaust gas recirculation rate caused by the execution of pulse supercharging when the pulse supercharging valve is operated during operation of the gas recirculation device to perform pulse supercharging, It is achieved by an internal combustion engine that further includes a flow rate adjusting structure in the exhaust passage, and wherein the fluctuation suppressing means suppresses the fluctuation by narrowing the flow rate adjusting structure. Also in the present invention, since the fluctuation suppressing means suppresses fluctuations in the exhaust gas recirculation rate caused by the execution of pulse supercharging, it is possible to provide an internal combustion engine that can properly execute EGR even when pulse supercharging is performed.

  ADVANTAGE OF THE INVENTION According to this invention, even if it implements pulse supercharging, the internal combustion engine which can perform the recirculation of exhaust gas appropriately can be provided.

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

  FIG. 1 is a diagram illustrating an internal combustion engine 1A including an EGR device and a pulse supercharging valve according to a first embodiment. The internal combustion engine 1A includes a piston 3 in a cylinder 2 in the same manner as a normal internal combustion engine. A combustion chamber 4 is formed in the upper part of the piston 3. An intake passage 5 for supplying intake air to the combustion chamber 4 and an exhaust passage 6 for discharging exhaust gas after combustion are provided. An intake valve 7 for adjusting the flow of intake air to the combustion chamber 4 is disposed on the intake passage 5 side. Similarly, an exhaust valve 8 for adjusting the flow of exhaust gas from the combustion chamber 4 is disposed on the exhaust passage 6 side. Further, an injector 9 for injecting fuel into the combustion chamber 4 is provided.

  The intake air is supplied to the combustion chamber 4 via an air cleaner 10 disposed on the upstream side of the intake passage 5. A purification catalyst 11 is disposed downstream of the exhaust passage 6.

  A pulse supercharging valve 12 is disposed in the intake passage 5. The structure of the pulse supercharging valve 12 is not particularly limited, but it is preferable to employ an on-off valve device that can open and close the intake passage 5 in a short time.

  The internal combustion engine 1 </ b> A includes an EGR device 30. The EGR device 30 includes, for example, an EGR passage 31 that connects the intake passage 5 downstream of the pulse supercharging valve 12 and the exhaust passage 6 upstream of the purification catalyst 11. A part of the exhaust gas is recirculated to the intake side by the EGR passage 31. An EGR valve 32 is provided in the middle of the EGR passage 31 as a flow rate control valve that controls the flow rate by adjusting the opening of the passage 31. The EGR rate is adjusted by the opening degree of the EGR valve 32. When the opening degree of the EGR valve 32 is increased, the amount of exhaust gas (EGR gas) recirculating in the EGR passage 31 can be increased to increase the EGR rate.

  Driving of the pulse supercharging valve 12 and the EGR valve 32 is controlled by an ECU (Electronic Control Unit) 20. The ECU 20 can also be used as an ECU that controls the internal combustion engine. The ECU 20 executes control of the entire internal combustion engine and drive control of the pulse supercharging valve 12 and the EGR valve 32 based on signals from sensors described later. Details of pulse supercharging and EGR control executed by the ECU 20 will be described later.

  The ECU 20 includes a memory (not shown) such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM stores a program related to the drive control of the internal combustion engine, a program related to the operation and EGR execution when performing pulse supercharging, a series of data used in these controls, and the like. The RAM also provides a processing area for executing the control.

  Further, another configuration provided in the internal combustion engine 1A will be described. In the intake passage 5, between the air cleaner 10 and the pulse supercharging valve 12, an air flow meter 21 for detecting the intake air amount from the upstream side, an intake pressure sensor 22 for detecting the intake air pressure, and a temperature of the intake air are detected. An intake air temperature sensor 23 is provided. Output signals from these sensors are supplied to the ECU 20.

  An in-cylinder pressure sensor 24 for detecting the pressure in the cylinder is provided at the head portion of the internal combustion engine. An exhaust pressure sensor 25 for detecting the exhaust gas pressure is provided in the exhaust passage 6. Output signals from these sensors are also supplied to the ECU 20.

  Also, around the crankshaft 13, a water temperature sensor 26 that detects the temperature of the circulating cooling water, an oil temperature sensor 27 that detects the temperature of the circulating lubricating oil, and rotation of the crank angle. A crank angle sensor 28 for detecting the number is provided. Output signals from these sensors are also supplied to the ECU 20. An output signal from the accelerator sensor 15 that detects the amount of depression of the accelerator 14 is also supplied to the ECU 20.

  As described above, the ECU 20 can accurately detect the state of the internal combustion engine because it receives detection signals from various sensors arranged at a plurality of locations. However, the plurality of sensors shown in FIG. 1 and their arrangement are illustrated as preferable for drive control of the internal combustion engine. In operation control when performing pulse supercharging described later, it is not essential to use signals from all the sensors shown here. That is, when the ECU 20 functions as a fluctuation suppressing unit that suppresses fluctuations in the exhaust gas recirculation rate during pulse supercharging, signals from the plurality of sensors are selected and used.

  Now, since the apparatus of this embodiment employs the pulse supercharging valve 12, it is necessary to consider the following points. A state when the pulse supercharging valve 12 is operated will be described with reference to FIG. FIG. 2 is a diagram schematically showing the periphery of the cylinder 2 and the pulse supercharging valve 12. FIG. 2A is a view showing a state in which a negative pressure is formed on the downstream side by the pulse supercharging valve 12, and FIG. 2B is a case where the pulse supercharging is performed by opening the pulse supercharging valve 12. It is the figure shown about the mode.

  As shown in FIG. 2A, by maintaining the pulse supercharge valve 12 closed during the intake stroke in which the intake valve 7 is opened and the piston 3 is lowered, a negative pressure is provided downstream of the pulse supercharge valve 12. Is formed. When the pulse supercharging valve 12 is opened at a predetermined time after the negative pressure is formed as shown in (B), the downstream air PA can flow into the combustion chamber 4 at once.

  Further, FIG. 3 is a view for explaining the relationship between the opening / closing period of the intake valve and the operation timing of the pulse supercharging valve 12. FIG. 3A is a diagram showing a standard opening / closing period of the intake valve 7. As shown in this figure, the intake valve 7 is set to open at a predetermined time before the top dead center (TDC) of the piston 3 and to be closed at a predetermined time after the bottom dead center (BDC).

  FIG. 3B shows the operation timing of the pulse supercharging valve 12. The pulse supercharging valve 12 is set to start and close when the intake valve 7 is opened, for example, and to open at a predetermined time before the intake valve 7 is closed. The hatched range in FIG. 3B is set in consideration of an increase in pumping loss that occurs in the intake passage, and the timing for opening the pulse supercharging valve 12 is selected within this range, so that pulse supercharging is performed. To be implemented. The opening timing is selected at a predetermined time according to the state of the internal combustion engine. The state when the pulse supercharging valve 12 is opened corresponds to FIG.

  Further, FIG. 4 is a diagram showing the intake system pressure and the exhaust system pressure in order to confirm the influence when the pulse supercharging is performed during the execution of the EGR control. FIG. 4A shows changes in intake system pressure and exhaust system pressure when pulse supercharging is not performed, and FIG. 4B shows changes in intake system pressure and exhaust system pressure when pulse supercharging is performed. A change in intake system pressure is indicated by a dotted line, and a change in exhaust system pressure is indicated by a solid line.

  Here, the area of the portion sandwiched between the dotted line and the solid line in FIG. 4 (partially blackened for easy confirmation) is the EGR amount. From a comparison between FIGS. 4A and 4B, it can be confirmed that the EGR rate decreases if pulse supercharging is performed during the execution of EGR. The main cause is that when the pulse supercharging is performed as shown in FIG. 4B, the pressure of the intake pressure system changes rapidly. That is, when pulse supercharging is executed, the differential pressure across the EGR passage 31 changes, and the EGR rate fluctuates.

  Therefore, in the internal combustion engine of the present embodiment, the ECU 20 functions as a fluctuation suppressing unit, and when the pulse supercharging is performed during the EGR execution, the change in the intake pressure of the internal combustion engine is confirmed and the planned EGR rate is maintained. Correct the opening of the EGR valve. The ECU 20 refers to an output signal from the air flow meter 21 and confirms an actual A / F value (actual A / F value). Then, when a change in the intake pressure system is recognized by comparing this with the target A / F value, the opening degree of the EGR valve is adjusted so as to maintain the planned EGR rate. Note that the target A / F value is a preferable A / F value when executing the EGR control. For example, the ECU 20 reads and refers to a value stored in advance in the ROM.

  Specifically, when the ECU 20 confirms that the actual A / F value is smaller than the target A / F value, the EGR rate that is left as it is is excessively high, so the EGR valve is corrected to the closed side. On the other hand, when it is confirmed that the actual A / F value is larger than the target A / F value, the EGR rate that is left as it is is too low, and the EGR valve is corrected to the open side. Since the ECU 20 appropriately corrects the opening degree of the EGR valve as described above, the necessary differential pressure can be maintained. Therefore, even if pulse supercharging is performed during EGR execution, fluctuations in the EGR rate can be suppressed. Hereinafter, the control content executed by the ECU 20 will be described in more detail.

  FIG. 5 is a flowchart showing an example of a routine when the ECU 20 of the internal combustion engine 1A performs pulse supercharging during execution of EGR. This routine is started when, for example, the ignition key of the internal combustion engine is turned on. The ECU 20 checks whether or not EGR is being executed (S11), and monitors whether or not the state of the internal combustion engine is in an operating region where pulse supercharging is to be performed (S12). As described above, since the output signals from various sensors are supplied to the ECU 20, the operating state of the internal combustion engine can be confirmed based on these signals. The ECU 20 performs pulse supercharging, for example, when it is confirmed that the internal combustion engine shifts from the low load state to the high load state. For example, the ECU 20 determines whether or not the internal combustion engine is in a state of performing pulse supercharging based on the relationship between the rotational speed of the internal combustion engine and the fuel injection hole amount, the difference between the target intake air amount and the actual intake air amount, or the like. to decide. It should be noted that a rotational speed-fuel injection hole amount map or the like may be stored in advance in the ROM of the ECU 20 so that these can be read and used at the time of the above determination.

  If the ECU 20 determines in step 12 (S12) that it is in the pulse supercharging operation region, for example, based on the opening / closing timing map stored in advance in the ROM, the pulse supercharging valve 12 according to the state of the internal combustion engine. To increase the intake air amount (S13). However, as described above, when the pulse supercharging is performed by operating the pulse supercharging valve 12, the intake system pressure changes. In the EGR control, for example, the opening degree of the EGR valve is determined by a map based on the rotational speed of the internal combustion engine and the fuel injection amount. Therefore, if the differential pressure before and after the EGR passage 31 changes due to the pulse supercharging, the actual EGR rate will vary from the planned EGR rate even if the valve opening is maintained. .

  Therefore, the ECU 20 confirms the difference between the actual A / F value and the target A / F value in the next step 14 (S14), so that the intake system pressure suitable for performing normal EGR control is maintained. Confirm whether or not.

  If the ECU 20 determines in step 14 that the actual A / F value is different from the target A / F value and the intake system pressure is not suitable for execution of EGR, the EGR valve 32 is opened in the next step 15. Correct the degree. That is, when the actual A / F value is larger than the target A / F value, the ECU 20 corrects the EGR valve to open because there is a possibility that the EGR rate may be lowered. On the contrary, if the actual A / F value is larger than the target A / F value, the EGR rate may be lowered, so the EGR valve is corrected to the open side. By correcting the opening degree of the EGR valve in this way, the actual A / F value is made to coincide with the target A / F value, the fluctuation of the EGR rate is suppressed, and the processing by this routine is ended.

  The above-described EGR valve opening correction by the ECU 20 may be obtained from a predetermined map for a correction amount corresponding to the difference between the target A / F value and the actual A / F value, or pulse supercharging is performed. Sometimes, a dedicated map may be prepared in advance for correction. The correction amount map and the pulse supercharging map used here may be stored in the ROM in the ECU 20. In addition, since the differential pressure between the intake and exhaust systems generated when pulse supercharging is performed is correlated with the operation period of pulse supercharging, the basic correction of the valve opening is related to the operation period of the pulse supercharging valve. The amount may be determined, and more detailed correction may be added with reference to the actual A / F value.

  In the internal combustion engine 1A having the pulse supercharging valve 12 described above, when the intake pressure changes due to pulse supercharging during execution of EGR, the ECU 20 corrects the opening degree of the EGR valve to change the EGR rate. To suppress fluctuations. Therefore, since pulse supercharging can be performed even during execution of EGR, output can be improved while maintaining emission appropriately.

  In the first embodiment, for example, the change in the intake system pressure is confirmed by the A / F value to correct the opening of the EGR valve. However, the intake system pressure is determined from the intake pressure sensor 22 and the exhaust pressure sensor 25. And the exhaust system pressure may be obtained, and the opening degree of the EGR valve may be corrected based on this differential pressure. Further, the routine shown in FIG. 5 corrects the opening degree of the EGR valve 32 when the intake system pressure changes by performing pulse supercharging, and suppresses fluctuations in the EGR rate, but performs pulse supercharging. Before the operation is performed, the opening of the EGR valve may be corrected in advance by predicting a change in the intake pressure system.

  Hereinafter, still another embodiment will be described. In the internal combustion engine 1A according to the first embodiment, the ECU 20 functioning as a fluctuation suppressing unit corrects the opening of the EGR valve 32 to cope with it, thereby suppressing the fluctuation of the EGR rate when the pulse supercharging is performed. Was adjusted to be executed properly. However, when pulse supercharging is performed, a reverse rotation state in which the intake system pressure becomes higher than the exhaust system pressure is also assumed. When this reverse state occurs, the gas flows backward through the EGR passage 31 and the EGR rate is significantly reduced. Therefore, a quick response is required. The embodiment described below is an embodiment of an internal combustion engine having a configuration for dealing with a reverse rotation state in which the pressure on the intake pressure side becomes higher than the exhaust pressure side.

  The structure of the internal combustion engine according to the second embodiment is the same as that of the internal combustion engine 1A of the first embodiment shown in FIG. The only difference is the variation suppression. Accordingly, the description will be made in the same manner using the reference numerals in FIG.

  In the first embodiment, the ECU 20 corrects the opening degree of the EGR valve when the EGR rate varies due to the pulse supercharging. On the other hand, the ECU 20 of this embodiment confirms the differential pressure between the intake system pressure and the exhaust system pressure, and if this differential pressure value is larger than a predetermined value, the EGR valve 32 is closed to reduce the EGR rate. To prevent.

  FIG. 6 is a flowchart illustrating an example of a routine when the ECU 20 of the internal combustion engine according to the second embodiment performs pulse supercharging during execution of EGR. The ECU 20 monitors whether or not EGR is being executed (S21) and whether or not the state of the internal combustion engine is in the operation region of pulse supercharging (S22). When it is determined that the operation region is the pulse supercharging operation, the pulse supercharging valve 12 is operated in the next step 23 (S23). The process so far is the same as the process in the first embodiment described above, but the process after the next step 24 (S24) is different.

  In step 24, the ECU 20 measures the differential pressure between the intake system pressure and the exhaust system pressure. If the differential pressure exceeds a predetermined value, the ECU 20 determines that the EGR gas may flow backward. And the fall of an EGR rate is avoided by closing the EGR valve 32 (S24). In the internal combustion engine of the present embodiment, the EGR valve is quickly closed when the reversal state is such that the flow of EGR gas flows backward, so that a decrease in the EGR rate can be reliably suppressed.

  In FIG. 6, the differential pressure between the intake system pressure and the exhaust system pressure is measured when pulse supercharging is performed, and the EGR valve 32 is closed when the intake system pressure is higher than the exhaust system pressure. This suppresses the effects of reverse rotation. However, it is not necessary to limit to the form in which the EGR valve 32 is closed after confirming the influence after the pulse supercharging in this way. That is, before the ECU 20 performs pulse supercharging, it may be predicted in advance that the intake system pressure and the exhaust system pressure are reversed, and the EGR valve may be closed.

  FIG. 7 is a flowchart in the case where the ECU 20 predicts the influence on the EGR and changes it so as to cope in advance before the pulse supercharging. The processing after step 33 (S33) is different from the processing in FIG. In the processing by this routine, the ECU 20 sets the pulse supercharging operation in accordance with the state of the internal combustion engine when it is in a state of performing pulse supercharging (S33). Then, a differential pressure between the intake pressure system and the exhaust pressure system is measured, and a simulation is performed when pulse supercharging is performed (S34). A program for performing such a simulation and a series of data used for the simulation may be stored in the ROM in advance.

  When the ECU 20 predicts that the intake system pressure and the exhaust system pressure are reversed by the simulation and the flow of the EGR gas is reversed, the ECU 20 closes the EGR valve 32 to avoid a decrease in the EGR rate. Thereafter, pulse supercharging is executed (S35). In the case of this modification, since the control for suppressing the EGR rate fluctuation is executed before the pulse supercharging, the influence on the EGR can be suppressed.

  Further, the internal combustion engine of the third embodiment will be described with reference to FIGS. As in the case of the second embodiment, the third embodiment is an internal combustion engine having a configuration for dealing with a case where the intake system pressure side is in a reverse rotation state where the exhaust system pressure side is higher than the exhaust system pressure side. FIG. 8 is a diagram illustrating an internal combustion engine 1B including an EGR device and a pulse supercharging valve according to the third embodiment. The same parts as those of the internal combustion engine 1A according to the first embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 9 is a flowchart showing an example of a routine executed by the ECU 20 of the internal combustion engine 1B.

  The internal combustion engine 1 </ b> B shown in FIG. 8 further includes a second EGR device 40. Similar to the EGR device (first EGR device) 30 described above, the second EGR device 40 is an EGR passage 41 that connects the intake passage 5 and the exhaust passage 6, and an EGR that adjusts the opening of the passage 41. A valve 42 is provided.

  In the first EGR device 30, the EGR passage 31 connects the intake passage 5 downstream of the pulse supercharging valve 12 and the exhaust passage 6 upstream of the purification catalyst 11. The route is high (High-Pressure-Loop). Therefore, it is easily affected by the pressure change when the pulse supercharging is executed. In contrast, the internal combustion engine 1 </ b> B of the present embodiment includes the second EGR device 40. In the second EGR device 40, the EGR passage 41 connects the intake passage 5 immediately after the air cleaner 10 and the exhaust passage 6 downstream of the purification catalyst 11. -Pressure-Loop). Therefore, the influence that the second EGR device 40 receives when the pressure change occurs in the intake pressure system by performing the pulse supercharging is reduced.

  Therefore, as shown in FIG. 9, the ECU 20 of the internal combustion engine 1 </ b> B changes the employed EGR device to the second EGR device 40 when the pulse supercharging is performed. This suppresses fluctuations in the EGR rate when the reverse phenomenon occurs. Note that the second EGR device 40 may be changed to the second EGR device 40 when the pulse supercharging is performed, and the opening degree of the EGR valve 42 may be further corrected to more reliably suppress the fluctuation of the EGR rate. Even when the opening degree of the EGR valve 42 is corrected in this way, the correction amount can be reduced as compared with the case of the first embodiment, so that it can be dealt with quickly.

  Furthermore, the internal combustion engine of the fourth embodiment will be described with reference to FIGS. 10 and 11. As in the case of the second embodiment, the fourth embodiment is also an internal combustion engine having a configuration for dealing with a case where the intake system pressure is in a reverse rotation state in which the intake system pressure is higher than the exhaust system pressure. FIG. 10 is a diagram illustrating an internal combustion engine 1 </ b> C including an EGR device and a pulse supercharging valve according to the fourth embodiment. In FIG. 10 as well, the same parts as those in FIG. FIG. 11 is a flowchart showing an example of a routine executed by the ECU 20 of the internal combustion engine 1C.

  The internal combustion engine 1C shown in FIG. 10 further includes a flow rate adjusting structure 50 that adjusts the exhaust gas flow rate on the exhaust passage 6 side. As such a flow rate adjusting structure, for example, a back pressure valve or a variable displacement turbo can be employed. These back pressure valves, variable capacity turbos, and the like are driven by the ECU 20 and driven in the direction in which the exhaust passage 6 is throttled (closed) to form a state in which the exhaust gas flowing through the exhaust passage 6 is difficult to flow. Rise.

  Therefore, as shown in FIG. 11, the ECU 20 of the internal combustion engine 1 </ b> C controls the flow rate adjusting structure 50 to increase the exhaust system pressure when pulse supercharging is performed. As a result, when the reverse phenomenon of the intake system pressure and the exhaust system pressure occurs as described above, it is quickly dealt with and the fluctuation of the EGR rate is suppressed.

  As in the case of the second embodiment, in the third and fourth embodiments, when the occurrence of a reverse state is predicted by simulation and it is determined that there is a possibility that the gas will flow backward, the second EGR device 40 is provided in advance. It is also possible to reduce the pressure change due to pulse supercharging and reduce the flow rate adjustment structure to raise the exhaust system pressure and suppress the fluctuation of the EGR rate.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is the figure shown about 1A of internal combustion engines provided with the EGR apparatus which concerns on Example 1, and a pulse supercharging valve. It is the figure which showed the circumference of a cylinder and a pulse supercharging valve typically, (A) is a figure showing a mode when negative pressure is formed in the downstream by a pulse supercharging valve, and (B) is a pulse supercharging. It is the figure shown about the mode at the time of opening a supply valve and performing pulse supercharging. It is the figure shown in order to demonstrate the relationship between the opening-and-closing period of an intake valve, and the operation timing of a pulse supercharging valve, (A) is the figure which showed the opening-and-closing period of a standard intake valve, (B) is a pulse It is a figure showing about the operation time of a supercharging valve. It is the figure which showed about the intake system pressure and the exhaust system pressure in order to confirm the influence when pulse supercharging was implemented during execution of EGR control. It is the flowchart which showed an example of the routine when ECU of 1A of internal combustion engines implements a pulse supercharging during EGR execution. 7 is a flowchart illustrating an example of a routine when the ECU of the internal combustion engine according to the second embodiment performs pulse supercharging during execution of EGR. It is a flowchart at the time of changing so that ECU may anticipate the influence on EGR and cope beforehand, before implementation of pulse supercharging. It is the figure shown about the internal combustion engine 1B provided with the EGR apparatus which concerns on Example 3, and a pulse supercharging valve. 12 is a flowchart illustrating an example of a routine when the ECU of the internal combustion engine according to the third embodiment performs pulse supercharging during execution of EGR. It is the figure shown about 1C of internal combustion engines provided with the EGR apparatus which concerns on Example 4, and a pulse supercharging valve. 10 is a flowchart illustrating an example of a routine that is executed by an ECU of the internal combustion engine according to a fourth embodiment.

Explanation of symbols

1 (1A to 1C) Internal combustion engine 5 Intake passage 6 Exhaust passage 12 Pulse supercharging valve 20 ECU (variation suppression means)
30, 40 Exhaust gas recirculation device 31 EGR passage 32 EGR valve (flow control valve)
50 Flow rate adjustment structure

Claims (3)

An internal combustion engine comprising an exhaust gas recirculation device that recirculates part of the exhaust gas in the exhaust passage to the intake passage, and a pulse supercharging valve that opens and closes the intake passage,
Fluctuation suppression means that suppresses fluctuations in the exhaust gas recirculation rate caused by performing the pulse supercharging when the pulse supercharging valve is operated while the exhaust gas recirculation device is being operated to perform the pulse supercharging. Prepared,
The internal combustion engine, wherein the fluctuation suppressing means suppresses the fluctuation by correcting an opening of a flow control valve provided in the exhaust gas recirculation device. An internal combustion engine comprising an exhaust gas recirculation device that recirculates part of the exhaust gas in the exhaust passage to the intake passage, and a pulse supercharging valve that opens and closes the intake passage,
Fluctuation suppression means that suppresses fluctuations in the exhaust gas recirculation rate caused by performing the pulse supercharging when the pulse supercharging valve is operated while the exhaust gas recirculation device is being operated to perform the pulse supercharging. Prepared,
The pulse of the first exhaust gas recirculation device and the intake passage in which the exhaust gas recirculation system connects the upstream side of the gas purification catalyst of the exhaust passage and downstream of the pulse supercharging valve of the intake passage A second exhaust gas recirculation device that connects the upstream side of the supercharging valve and the downstream side of the purification catalyst in the exhaust passage ;
When the fluctuation suppression means performs the pulse supercharging , the fluctuation is suppressed by changing the exhaust gas recirculation device from the first exhaust gas recirculation device to the second exhaust gas recirculation device. An internal combustion engine characterized by suppressing. An internal combustion engine comprising an exhaust gas recirculation device that recirculates part of the exhaust gas in the exhaust passage to the intake passage, and a pulse supercharging valve that opens and closes the intake passage,
Fluctuation suppression means that suppresses fluctuations in the exhaust gas recirculation rate caused by performing the pulse supercharging when the pulse supercharging valve is operated while the exhaust gas recirculation device is being operated to perform the pulse supercharging. Prepared,
The exhaust passage further includes a flow rate adjusting structure,
The internal combustion engine, wherein the fluctuation suppressing means suppresses the fluctuation by restricting the flow rate adjusting structure.

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