JP2009185751A - Control device for internal combustion engine - Google Patents

Abstract

In a control device for an internal combustion engine, a technique for suppressing moisture and foreign matter from adhering to an intercooler is provided.
SOLUTION: An intercooler 8 disposed in an intake passage 3 of an internal combustion engine 1 and a part of the exhaust gas from the exhaust passage 4 of the internal combustion engine 1 is returned to the intake passage 3 upstream of the intercooler 8 as low-pressure EGR gas. A low-pressure EGR device 30 to be operated, and a flow rate control valve 9 for controlling the flow rate of intake air in the lower half of the intercooler 8, the new air amount gn being smaller than the predetermined fresh air amount G1, and the low-pressure EGR When the valve opening degree pegrl is equal to or greater than the predetermined opening degree P1, the flow rate control valve 9 is closed to prevent the intake air from flowing in the lower half of the intercooler 8.
[Selection] Figure 1

Description

  The present invention relates to a control device for an internal combustion engine.

  An intercooler disposed in the intake passage of the internal combustion engine, a low pressure EGR device that recirculates part of the exhaust gas as low pressure EGR gas from the exhaust passage of the internal combustion engine to the intake passage upstream of the intercooler, and bypasses the intercooler for intake air And a bypass passage for changing the amount of gas flowing through the bypass passage so that the amount of exhaust gas recirculated into the combustion chamber (low-pressure EGR gas amount) can be changed as quickly as possible. For example, see Patent Document 1).

  A high-pressure EGR device that recirculates a portion of the exhaust gas as a high-pressure EGR gas from an exhaust passage upstream of the turbine to an intake passage downstream of the compressor, and a part of the exhaust gas from the exhaust passage downstream of the turbine to the intake passage upstream of the compressor And a low-pressure EGR device that recirculates the fuel as low-pressure EGR gas, and discloses a technique for controlling the mixing ratio of the high-pressure EGR gas and the low-pressure EGR gas based on the correlation between the mixing ratio and the fuel consumption ( For example, see Patent Document 2).

  The fin provided inside the drain separator casing connected to the intake passage inlet is inclined so that the lower end of the fin is located downstream of the air flow flowing through the drain separator casing with respect to the upper end of the fin, and the flow velocity between the fins is high. A technique is disclosed in which the force of airflow is used as the force of dropping a water droplet and the condensed water is quickly collected without being scattered (see, for example, Patent Document 3).

An intercooler disposed in the intake passage of the internal combustion engine, a low-pressure EGR device that recirculates part of the exhaust gas as low-pressure EGR gas from the exhaust passage of the internal combustion engine to the intake passage upstream of the intercooler, and a lower portion of the intercooler and the exhaust A condensed water drainage passage connecting the passage, an on-off valve interposed in the condensed water drainage passage, when the pressure in the intercooler is in an extremely low power range operating state lower than the pressure in the exhaust passage, and In addition, a technique is disclosed that includes an on-off valve control means for closing the on-off valve when in an operating state in a high output range (see, for example, Patent Document 4).
JP-A-2005-146919 JP 2007-255323 A JP-A-10-259732 Japanese Patent No. 3666583

  By the way, if a low pressure EGR device that recirculates a part of the exhaust gas as low pressure EGR gas from the exhaust passage of the internal combustion engine to the intake passage upstream of the intercooler is used to recirculate the low pressure EGR gas to the intake passage, the intake air containing the low pressure EGR gas Will flow into the intercooler. Here, the low pressure EGR gas contains moisture and foreign matter. For this reason, moisture or foreign matter that is contained in the low-pressure EGR gas and recirculated to the intake passage may adhere to the intercooler. In order to suppress the adhesion of moisture and foreign matter into the intercooler, a technique is adopted in which a bypass passage for bypassing the intercooler is provided in the intake air so that moisture and foreign matter are not taken into the intercooler, as in Patent Document 1. There have been cases. However, providing a bypass passage is difficult to mount due to restrictions on mounting. Also, there was no measure for removing moisture and foreign matters once adhered to the intercooler.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for suppressing moisture and foreign matter from adhering to an intercooler in a control device for an internal combustion engine. is there.

In the present invention, the following configuration is adopted. That is, the present invention
An intercooler disposed in the intake passage of the internal combustion engine;
An EGR device that recirculates part of the exhaust gas from the exhaust passage of the internal combustion engine as EGR gas to the intake passage upstream of the intercooler;
A flow rate control means for controlling the flow rate of intake air in a part of the intercooler;
With
The control apparatus for an internal combustion engine, wherein when the internal combustion engine is in a predetermined state, the flow rate control means reduces a flow rate of intake air in a part of the intercooler.

  Here, when the internal combustion engine is in a predetermined state, reducing the flow rate of intake air in part of the intercooler by the flow rate control means includes setting the flow rate of intake air to zero.

  According to the present invention, by reducing the amount of intake air flowing in a part of the intercooler, the amount of heat released from the intercooler is reduced and the intake air is not cooled excessively, and condensed water is generated from the intake air in the intercooler. Can be suppressed. Along with this, a decrease in intake air temperature is suppressed, so that misfire of the internal combustion engine can be suppressed. In addition, by reducing the amount of intake air flowing in a part of the intercooler, the intake air flow velocity in parts other than the part in the intercooler increases, and moisture and foreign matter adhering to parts other than the part in the intercooler are removed. Can be blown away. By these, it can suppress that a water | moisture content and a foreign material adhere in an intercooler.

  On the other hand, even if the flow rate of the intake air in a part of the intercooler is reduced, the amount of EGR gas recirculated from the EGR device itself is not changed, so that the desired emission by performing the EGR operation can be maintained.

  The case where the internal combustion engine is in a predetermined state may be a case where the intake air amount is less than the first predetermined amount and the EGR gas amount recirculated by the EGR device is equal to or greater than the second predetermined amount. Further, when the internal combustion engine is in a predetermined state, it may be a case other than the previous case.

  The first predetermined amount means that if the intake air amount is smaller than that, even if the intake air flow in a part of the intercooler is reduced, the intake air is clogged or the intake air temperature is excessively raised. This is a threshold value that does not cause The second predetermined amount is a threshold at which condensed water is not generated from the intake air containing the EGR gas in the intercooler when the amount of EGR gas is smaller than that.

  According to this invention, it can suppress that a water | moisture content and a foreign material adhere in an intercooler.

  When the EGR gas amount is smaller than the second predetermined amount, the flow rate control means does not reduce the flow rate of the intake air in a part of the intercooler. This is because when the amount of EGR gas is small, condensed water is not generated from the intake air containing the EGR gas in the intercooler.

  Here, when the intake air amount is smaller than the first predetermined amount and the EGR gas amount is smaller than the second predetermined amount, it corresponds to the early stage of acceleration. Since the flow rate control means does not reduce the flow rate of intake air in a part of the intercooler in the early stage of acceleration, the acceleration performance can be improved by cooling more intake air and sending the cooled intake air to the internal combustion engine.

  The flow rate control means is a flow rate control valve that is arranged in the intercooler and controls a flow rate of intake air in a part of the intercooler. When the internal combustion engine is in a predetermined state, the flow rate control unit The valve may be controlled to the closed side.

  According to the present invention, the flow rate of intake air in a part of the intercooler can be reduced by controlling the flow rate control valve to the closed side.

  ADVANTAGE OF THE INVENTION According to this invention, in the control apparatus of an internal combustion engine, it can suppress that a water | moisture content and a foreign material adhere in an intercooler.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the control device for an internal combustion engine according to the present embodiment is applied and an intake system / exhaust system thereof. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-stroke cycle diesel engine having four cylinders 2. The internal combustion engine 1 is mounted on a vehicle. An intake passage 3 and an exhaust passage 4 are connected to the internal combustion engine 1.

  In the middle of the intake passage 3 connected to the internal combustion engine 1, a turbocharger compressor 5a that operates using exhaust energy as a drive source is disposed. A first throttle valve 6 for adjusting the flow rate of intake air flowing through the intake passage 3 is disposed in the intake passage 3 upstream of the compressor 5a. The first throttle valve 6 is opened and closed by an electric actuator. In the intake passage 3 upstream of the first throttle valve 6, an air flow meter 7 that outputs a signal corresponding to the flow rate of fresh intake air (hereinafter referred to as fresh air) flowing through the intake passage 3 is disposed. Yes. The air flow meter 7 measures the amount of fresh air in the internal combustion engine 1.

  An intercooler 8 that performs heat exchange between the intake air and the outside air is arranged in the intake passage 3 downstream of the compressor 5a. As shown in FIG. 2, the intercooler 8 includes an inlet side space portion 81 extending vertically from a portion connected to the intake passage 3, and a plurality of heat exchange tubes arranged vertically from the inlet side space portion 81. 82 and fins (not shown) disposed between the tubes 82. As shown in FIGS. 1 and 2, the intercooler 8 is halfway up and down in the entrance space 81 in the middle of the entrance space 81, specifically below the portion connected to the intake passage 3. The flow rate control valve 9 is provided at the position to be set. The flow rate control valve 9 can control the flow rate of intake air in the lower half of the intercooler 8 by opening and closing. This flow rate control valve 9 is opened and closed by an electric actuator. The flow rate control valve 9 corresponds to the flow rate control means of the present invention. As the flow rate control means, it is only necessary to be able to control the flow rate of intake air in a part of the intercooler 8, and for example, it may be provided in an unillustrated outlet space where the tube 82 of the intercooler 8 joins. Alternatively, each of the tubes 82 may be provided with an on-off valve. Further, the portion where the flow rate of the intake air is restricted by the flow rate control means is not limited to the portion where the capacity in the intercooler 8 is halved.

  A second throttle valve 10 that adjusts the flow rate of the intake air flowing through the intake passage 3 is provided in the intake passage 3 downstream of the intercooler 8. The second throttle valve 10 is opened and closed by an electric actuator. The intake passage 3 and the above-described devices arranged in the intake passage 3 constitute an intake system of the internal combustion engine 1.

On the other hand, in the middle of the exhaust passage 4 connected to the internal combustion engine 1, there is a turbocharger turbine 5.
b is arranged. An exhaust purification device 11 is arranged in the exhaust passage 4 downstream of the turbine 5b.

  The exhaust emission control device 11 is configured to include an oxidation catalyst and a particulate filter (hereinafter simply referred to as a filter) disposed at the subsequent stage of the oxidation catalyst. The filter carries a NOx storage reduction catalyst. The exhaust passage 4 and the devices arranged in the exhaust passage 4 constitute an exhaust system of the internal combustion engine 1.

  The internal combustion engine 1 is provided with a low-pressure EGR device 30 that recirculates (recirculates) part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3 at a low pressure. The low pressure EGR device 30 includes a low pressure EGR passage 31, a low pressure EGR valve 32, and a low pressure EGR cooler 33. This low pressure EGR device 30 corresponds to the EGR device of the present invention.

  The low pressure EGR passage 31 connects the exhaust passage 4 downstream of the exhaust purification device 11 and the intake passage 3 upstream of the compressor 5 a and downstream of the first throttle valve 6. That is, the low pressure EGR passage 31 recirculates exhaust gas from the exhaust passage 4 to the intake passage 3 upstream of the intercooler 8. Exhaust gas is fed into the internal combustion engine 1 at low pressure through the low pressure EGR passage 31. In this embodiment, the exhaust gas recirculated through the low pressure EGR passage 31 is referred to as low pressure EGR gas. This low-pressure EGR gas corresponds to the EGR gas of the present invention.

  The low-pressure EGR valve 32 is disposed in the low-pressure EGR passage 31 and adjusts the amount of low-pressure EGR gas flowing through the low-pressure EGR passage 31 by adjusting the passage sectional area of the low-pressure EGR passage 31. The low pressure EGR valve 32 is opened and closed by an electric actuator. The adjustment of the low pressure EGR gas amount can be performed by a method other than the adjustment of the opening degree of the low pressure EGR valve 32. For example, the differential pressure between the upstream and downstream of the low pressure EGR passage 31 can be changed by adjusting the opening of the first throttle valve 6, thereby adjusting the amount of the low pressure EGR gas.

  The low pressure EGR cooler 33 is disposed in the low pressure EGR passage 31 upstream of the low pressure EGR valve 32, and performs heat exchange between the low pressure EGR gas passing through the low pressure EGR cooler 33 and the engine coolant of the internal combustion engine 1. The temperature of the low pressure EGR gas is lowered.

  On the other hand, the internal combustion engine 1 is provided with a high-pressure EGR device 40 that recirculates a part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3 at a high pressure. The high pressure EGR device 40 includes a high pressure EGR passage 41 and a high pressure EGR valve 42.

  The high-pressure EGR passage 41 connects the exhaust passage 4 upstream of the turbine 5b and the intake passage 3 downstream of the compressor 5a. Exhaust gas is fed into the internal combustion engine 1 at a high pressure through the high pressure EGR passage 41. In this embodiment, the exhaust gas recirculated through the high pressure EGR passage 41 is referred to as high pressure EGR gas.

  The high-pressure EGR valve 42 is disposed in the high-pressure EGR passage 41 and adjusts the passage cross-sectional area of the high-pressure EGR passage 41 to adjust the amount of high-pressure EGR gas flowing through the high-pressure EGR passage 41. The high pressure EGR valve 42 is opened and closed by an electric actuator. The high pressure EGR gas amount can be adjusted by a method other than the adjustment of the opening degree of the high pressure EGR valve 42. For example, the differential pressure between the upstream and downstream of the high pressure EGR passage 41 can be changed by adjusting the opening of the second throttle valve 10, thereby adjusting the amount of high pressure EGR gas. Further, when the turbine 5b of the turbocharger is a variable capacity type, the amount of high-pressure EGR gas can be adjusted also by adjusting the opening degree of the nozzle vane that changes the flow rate characteristic of the turbine 5b.

  The internal combustion engine 1 configured as described above is provided with an ECU 12 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 12 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  Various sensors such as an air flow meter 7 are connected to the ECU 12 via electric wiring, and output signals of these various sensors are input to the ECU 12.

  On the other hand, the electric actuators of the first throttle valve 6, the flow rate control valve 9, the second throttle valve 10, the low-pressure EGR valve 32, and the high-pressure EGR valve 42 are connected to the ECU 12 through electric wiring. These devices are controlled by the ECU 12.

  The ECU 12 receives an output signal from a crank position sensor, an accelerator position sensor, etc. (not shown) to determine the operating state of the internal combustion engine 1, and electrically controls the internal combustion engine 1 and the above devices based on the determined engine operating state. To do.

  For example, when the low pressure EGR valve 32 is opened, the low pressure EGR passage 31 becomes conductive, and a part of the exhaust gas flowing out from the exhaust purification device 11 flows into the intake passage 3 via the low pressure EGR passage 31 as low pressure EGR gas. To do. The low pressure EGR gas flowing into the intake passage 3 is recirculated to the internal combustion engine 1 via the compressor 5a and the intercooler 8.

  When the high-pressure EGR valve 42 is opened, the high-pressure EGR passage 41 becomes conductive, and a part of the exhaust gas flowing through the exhaust passage 4 flows into the intake passage 3 via the high-pressure EGR passage 41 as high-pressure EGR gas. Recirculate to engine 1.

  In this way, an EGR operation in which a part of the exhaust gas is recirculated to the internal combustion engine 1 through the low pressure EGR passage 31 and / or the high pressure EGR passage 41 as EGR gas (low pressure EGR gas and high pressure EGR gas are collectively referred to as EGR gas). By performing this, the combustion temperature of the internal combustion engine 1 can be lowered, the amount of NOx emitted during the combustion process can be reduced, and the emission can be reduced.

  Here, the conditions of the operating state of the internal combustion engine 1 that can suitably execute the EGR operation using the low-pressure EGR device 30 and the EGR operation using the high-pressure EGR device 40 are obtained in advance by experiments or the like. In the present embodiment, the exhaust gas recirculation is performed by switching the EGR operation using the low pressure EGR device 30 and the high pressure EGR device 40 according to the operation state of the internal combustion engine 1 or using them together.

  FIG. 3 is a diagram showing an EGR operation switching pattern determined for each operating state region of the internal combustion engine 1. The horizontal axis in FIG. 3 represents the engine speed of the internal combustion engine 1, and the vertical axis represents the torque of the internal combustion engine 1.

  In FIG. 3, a region HPL is a region where the operating state of the internal combustion engine 1 is low torque and low rotation, and here, EGR operation using the high pressure EGR device 40 is performed. The region LPL + HPL is a region where the operation state of the internal combustion engine 1 is a medium-torque / medium-rotation region, and here, EGR operation using both the high pressure EGR device 40 and the low pressure EGR device 30 is used together. The region LPL is a region where the operating state of the internal combustion engine 1 is high torque and high rotation, and here, EGR operation using the low pressure EGR device 30 is performed.

  As described above, the EGR operation can be performed in a wide range of operation by switching the EGR operation using the low pressure EGR device 30 and the high pressure EGR device 40 or using them together.

  By the way, when the low pressure EGR device 30 is used to return the low pressure EGR gas to the intake passage, the intake air including the low pressure EGR gas flows into the intercooler 8. Here, since the low pressure EGR gas is exhaust gas, it contains moisture and foreign matter generated by the combustion of the internal combustion engine 1. For this reason, when the intake air is cooled in the intercooler 8, the water may be condensed and the water contained in the low-pressure EGR gas and returned to the intake passage 3 may adhere to the intercooler 8. In addition, foreign matter contained in the low pressure EGR gas and returning to the intake passage 3 may adhere to the intercooler 8.

  Therefore, in this embodiment, the flow rate control valve 9 is closed when the fresh air amount is smaller than the predetermined fresh air amount G1 and the opening degree of the low pressure EGR valve 32 is equal to or larger than the predetermined opening degree P1. A specific range for closing the flow rate control valve 9 is an arrow range shown in FIG. 4 where the horizontal axis represents the torque of the internal combustion engine 1 and the vertical axis represents the fresh air amount and the low-pressure EGR valve opening.

  Here, the case where the fresh air amount is smaller than the predetermined fresh air amount G1 corresponds to the case where the intake air amount including the fresh air and the low-pressure EGR gas (in other words, the compressor passing gas amount) is smaller than the first predetermined amount. That is, the predetermined fresh air amount G1 is a threshold value at which the compressor passing gas amount becomes the first predetermined amount, and the first predetermined amount is the intake air in the lower half in the intercooler 8 when the compressor passing gas amount is smaller than that. Even if the flow of the air is blocked, the intake air flowing through the upper half of the intercooler 8 is clogged or the intake air temperature is excessively raised.

  Further, the case where the opening of the low pressure EGR valve 32 is equal to or greater than the predetermined opening P1 corresponds to the case where the amount of low pressure EGR gas is equal to or greater than the second predetermined amount. That is, the predetermined opening degree P1 is a threshold value at which the low pressure EGR gas amount becomes the second predetermined amount, and the second predetermined amount includes the low pressure EGR gas in the intercooler 8 when the low pressure EGR gas amount is smaller than that. This is a threshold at which condensed water is not generated from the intake air.

  The operating state of the internal combustion engine 1 in the range in which the flow rate control valve 9 is closed is a hatched region excluding the low torque low rotation side in the region LPL + HPL as shown in FIG. Further, when the horizontal axis indicates the engine speed or torque of the internal combustion engine 1 and the vertical axis indicates the ratio of EGR gas, the range in which the flow rate control valve 9 is closed in FIG. 5, the low pressure EGR gas and the high pressure EGR gas are mixed. The low-pressure EGR gas amount in the mixed range is within the range indicated by the arrow excluding the range where the amount is less than the second predetermined amount.

  According to this embodiment, when the fresh air amount is smaller than the predetermined fresh air amount G1 and the opening degree of the low pressure EGR valve 32 is equal to or larger than the predetermined opening degree P1, the flow rate control valve 9 is closed. In addition, it is possible to prevent the intake air from flowing in the lower half of the intercooler 8.

  If the flow of the intake air in the lower half of the intercooler 8 is blocked in this way, the amount of heat released to the intake air of the intercooler 8 is suppressed and the intake air is not excessively cooled, and is included in the intake air, particularly in the intake air. The generation of condensed water from the low pressure EGR gas generated can be suppressed. Along with this, a decrease in intake air temperature is suppressed, so that misfire of the internal combustion engine 1 into which the intake air is introduced can be suppressed. Further, by blocking the flow of intake air in the lower half of the intercooler 8, the amount of intake air flowing through the upper half of the intercooler 8 increases, and the intake air flow velocity flowing through the upper half of the intercooler 8 increases. Moisture and foreign matter adhering to the upper half of the cooler 8 can be blown off. As described above, by suppressing the generation of condensed water in the intercooler 8 and blowing away moisture and foreign matter adhering to the upper half of the intercooler 8, moisture and foreign matter adhere to the intercooler 8. Can be suppressed.

  On the other hand, even if the flow of intake air in the lower half of the intercooler 8 is blocked, the amount of low-pressure EGR gas that is recirculated from the low-pressure EGR device 30 is not changed, so that the exhaust gas is discharged from the internal combustion engine 1 by performing the EGR operation. The desired emission of reducing NOx emission can be maintained.

  Here, when the low pressure EGR valve 32 is close to the predetermined opening P1, the flow rate control valve 9 is opened to prevent the intake air from flowing in the lower half of the intercooler 8. This is because, when the opening of the low pressure EGR valve 32 is closer to the opening than the predetermined opening P1, the low pressure EGR gas recirculated from the low pressure EGR device 30 in the intercooler 8 is small, and the condensed water from the intake air containing the low pressure EGR gas. This is because no occurrence occurs.

  Further, here, when the fresh air amount is smaller than the predetermined fresh air amount G1 and the opening degree of the low pressure EGR valve 32 is closer to the closing side than the predetermined opening degree P1, this corresponds to the initial acceleration of the vehicle. In this case, since the flow control valve 9 is opened and the flow of the intake air in the lower half of the intercooler 8 is not blocked, more intake air is cooled by the intercooler 8 and the cooled intake air is sent to the internal combustion engine 1. The acceleration of the vehicle can be improved. That is, when the vehicle is accelerated, the flow rate control valve 9 is opened to cool the intake air. When the vehicle is decelerated, the flow rate control valve 9 is closed in order to increase the intake air flow velocity in the intercooler 8.

  Next, a control routine for the flow rate control valve 9 according to this embodiment will be described. FIG. 6 is a flowchart showing a control routine of the flow rate control valve 9 according to this embodiment. This routine is repeatedly executed every predetermined time.

  In step S101, the ECU 12 detects the fresh air amount gn. The new air amount is detected from the output signal of the air flow meter 7.

  In step S102, the ECU 12 calculates the engine speed and the fuel injection amount. The engine speed is calculated from an output signal of a crank position sensor (not shown). The fuel injection amount is calculated from an output signal of an accelerator position sensor (not shown).

  In step S103, the ECU 12 calculates a low pressure EGR valve opening degree pegrl. The low pressure EGR valve opening degree pegrl is calculated from a map obtained in advance through experiments or the like based on the engine speed and the fuel injection amount calculated in step S102.

  In step S104, the ECU 12 determines whether or not the fresh air amount gn is smaller than a predetermined fresh air amount G1.

  If it is determined in step S104 that the fresh air amount gn is smaller than the predetermined fresh air amount G1, the process proceeds to step S105. If it is determined in step S104 that the fresh air amount gn is greater than or equal to the predetermined fresh air amount G1, the process proceeds to step S107.

  In step S105, the ECU 12 determines whether or not the low pressure EGR valve opening degree pegrl is equal to or greater than a predetermined opening degree P1.

  If it is determined in step S105 that the low pressure EGR valve opening degree pegrl is equal to or greater than the predetermined opening degree P1, the process proceeds to step S106. If it is determined in step S105 that the low pressure EGR valve opening degree pegrl is closer to the closing side than the predetermined opening degree P1, the process proceeds to step S107.

In step S106, the ECU 12 closes the flow rate control valve 9. When the process proceeds to step S106, the fresh air amount gn is smaller than the predetermined fresh air amount G1, and the low pressure EGR valve opening degree pegrl is equal to or larger than the predetermined opening degree P1. By closing the flow rate control valve 9, the flow of intake air in the lower half of the intercooler 8 is blocked. Thereby, generation | occurrence | production of condensed water in the intercooler 8 is suppressed, and it suppresses that a water | moisture content and a foreign material adhere in the intercooler 8 by blowing off the water | moisture content and the foreign material adhering to the upper half in the intercooler 8. . After the processing of this step, this routine is once ended.

  On the other hand, in step S107, the ECU 12 opens the flow rate control valve 9. When the process proceeds to step S <b> 107, intake air is circulated throughout the intercooler 8 by opening the flow rate control valve 9. After the processing of this step, this routine is once ended.

  According to the routine described above, the flow rate control valve 9 is closed when the fresh air amount gn is smaller than the predetermined fresh air amount G1 and the low pressure EGR valve opening degree pegrl is equal to or larger than the predetermined opening degree P1. Can do.

  In the above embodiment, the flow rate control valve 9 is controlled only to open or close, but the present invention is not limited to this. For example, when the flow rate control valve 9 is closed, the flow rate control valve 9 may be controlled not to be fully closed but to the closed side. Even when the flow rate control valve 9 is closed, the flow rate of the intake air flowing through the lower half of the intercooler 8 is reduced, and this also provides the same effect as when the flow rate control valve 9 is fully closed. Can do. In the present embodiment, the flow rate control valve 9 is closed when the fresh air amount gn is smaller than the predetermined fresh air amount G1 and the low pressure EGR valve opening degree pegrl is equal to or larger than the predetermined opening degree P1. In other cases, the present invention includes closing the flow rate control valve 9.

  The control device for an internal combustion engine according to the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the gist of the present invention.

1 is a diagram showing a schematic configuration of an internal combustion engine and an intake system / exhaust system thereof according to Embodiment 1. FIG. FIG. 3 is a perspective view illustrating a part of the intercooler according to the first embodiment. The figure which shows the use area | region of the low pressure EGR apparatus according to the driving | running state of the internal combustion engine which concerns on Example 1, and a high pressure EGR apparatus. The figure which shows the range which closes the flow volume control valve with respect to the fresh air quantity according to the torque which concerns on Example 1, and a low pressure EGR valve opening degree. The figure which shows the range which closes the flow volume control valve with respect to the EGR gas ratio according to the engine speed or torque which concerns on Example 1. FIG. 3 is a flowchart showing a control routine of a flow rate control valve according to the first embodiment.

Explanation of symbols

1 Internal combustion engine 2 Cylinder 3 Intake passage 4 Exhaust passage 5a Compressor 5b Turbine 6 First throttle valve 7 Air flow meter 8 Intercooler 9 Flow rate control valve 10 Throttle valve 11 Exhaust gas purification device 12 ECU
30 Low pressure EGR device 31 Low pressure EGR passage 32 Low pressure EGR valve 33 Low pressure EGR cooler 40 High pressure EGR device 41 High pressure EGR passage 42 High pressure EGR valve 81 Inlet space 82 Heat exchange tube

Claims (3)

An intercooler disposed in the intake passage of the internal combustion engine;
An EGR device that recirculates part of the exhaust gas from the exhaust passage of the internal combustion engine as EGR gas to the intake passage upstream of the intercooler;
A flow rate control means for controlling the flow rate of intake air in a part of the intercooler;
With
A control apparatus for an internal combustion engine, wherein when the internal combustion engine is in a predetermined state, the flow rate of the intake air in a part of the intercooler is reduced by the flow rate control means.   The case where the internal combustion engine is in a predetermined state is a case where the intake air amount is less than a first predetermined amount and the amount of EGR gas recirculated by the EGR device is equal to or greater than a second predetermined amount. The control apparatus for an internal combustion engine according to claim 1. The flow rate control means is a flow rate control valve that is arranged in the intercooler and controls the flow rate of intake air in a part of the intercooler,
3. The control device for an internal combustion engine according to claim 1, wherein when the internal combustion engine is in a predetermined state, the flow amount control valve is controlled to be closed.

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