JP2015178777A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To warm up an EGR valve early and thus enables early start of introduction of EGR gas while no condensation water is present around the EGR valve in an internal combustion engine.SOLUTION: An internal combustion engine includes: an EGR passage 34 for interconnecting an intake passage 12 and an exhaust passage 14 upstream of a compressor 22a for supercharging intake air; and an EGR valve 38 arranged at an end on the intake passage 12 side in the EGR passage 34 or in the middle of the EGR passage 34.The internal combustion engine further includes: a communication passage 50 interconnecting the EGR passage 34 and the exhaust passage 14; and an on-off valve 52 for opening/closing the communication passage 50. The communication passage 50 is connected to the EGR passage 34 at a position immediately above the EGR valve 38 in the flowing direction of the EGR gas and is connected to the exhaust passage 14 so that a downstream side catalyst 30 is interposed in a portion between a connection position 34a of the EGR passage 34 and the exhaust passage 14 and a connection position 50a of the communication passage 50.

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine capable of introducing EGR gas.

  Conventionally, for example, Patent Document 1 discloses an internal combustion engine with a turbocharger. This internal combustion engine includes an intercooler that cools supercharged intake air and an EGR cooler that cools EGR gas introduced into an intake passage upstream of the compressor. The amount of EGR gas is controlled so that condensed water is not generated in the intercooler and the EGR cooler.

JP 2012-087779 A

  Here, a configuration is assumed in which an EGR valve for adjusting the flow rate of EGR gas flowing through the EGR passage is provided at an end portion of the EGR passage on the intake passage side or in the middle of the EGR passage. In the initial warm-up period after starting from the cold state, the EGR valve is closed because condensed water is likely to be generated. However, even if the EGR valve is closed, the EGR passage on the upstream side of the EGR gas flow with respect to the EGR valve is filled with the exhaust gas due to the exhaust pulsation, and gas exchange occurs constantly here. For this reason, dew condensation may occur when moisture in the exhaust gas touches the cold EGR valve. Thus, when the EGR valve is closed and cold, condensed water can be generated on and near the valve surface on the exhaust passage side of the EGR valve.

  If the EGR valve is opened and EGR gas is introduced without any consideration for the generation of condensed water in the EGR valve as described above, the condensed water flows into the intake passage. On the other hand, if the introduction of EGR gas is prohibited until the condensed water in the EGR valve disappears due to complete warming up of the internal combustion engine, the fuel efficiency effect due to the introduction of EGR gas cannot be obtained.

  The present invention has been made to solve the above-described problems, so that the introduction of EGR gas can be started early in the state where the EGR valve is warmed up early and condensed water does not exist around the EGR valve. An object of the present invention is to provide an internal combustion engine.

The first invention is an internal combustion engine,
A compressor for supercharging intake air;
An EGR passage connecting an intake passage and an exhaust passage upstream of the compressor;
An EGR valve that is provided in an end portion of the EGR passage on the side of the intake passage or in the middle of the EGR passage, and adjusts the flow rate of EGR gas flowing through the EGR passage;
A communication passage connecting the EGR passage and the exhaust passage;
An opening and closing valve for opening and closing the communication path,
The communication passage is connected to the EGR passage at a position immediately above the EGR valve in the EGR gas flow direction, and a pressure difference with respect to the pressure in the exhaust passage occurs at the connection position of the EGR passage and the exhaust passage. It is connected to the exhaust passage at the position where the pressure difference or the pressure difference occurs with the operation of a predetermined actuator.

The second invention is the first invention, wherein
When the EGR valve is closed, when the condensed water is generated in the EGR valve, or when there is a possibility that it is generated, a control means for opening the open / close valve is further provided.

The third invention is the second invention, wherein
The case where condensed water is generated or possibly generated in the EGR valve is a case where the temperature of the EGR valve becomes a predetermined value or less.

Moreover, 4th invention is set in any one of 1st-3rd invention,
In the exhaust passage, at least one device for lowering the pressure in the exhaust passage is interposed between the connection position of the EGR passage and the exhaust passage and the connection position of the communication passage and the exhaust passage. It is characterized by that.

Moreover, 5th invention is set in any one of 1st-3rd invention,
In the exhaust passage, the exhaust passage is throttled when the opening / closing valve is opened at a position between the connection position of the EGR passage and the exhaust passage and the connection position of the communication passage and the exhaust passage. A throttle valve is arranged as the predetermined actuator.

Moreover, 6th invention is set in any one of 1st-5th invention,
An EGR cooler that is arranged in the EGR passage upstream of the EGR gas flow from the EGR valve and cools the EGR gas flowing through the EGR passage;
The connection position between the communication passage and the exhaust passage is provided on the upstream side of the flow of exhaust gas in the exhaust passage from the connection position between the EGR passage and the exhaust passage.

  According to the first invention, if the open / close valve is opened when the EGR valve is closed when it is cold, a part of the exhaust gas flowing through the exhaust passage touches the EGR valve using the EGR passage and the communication passage. It can be made to flow while. As a result, the EGR valve can be heated by the heat of the exhaust gas. Thereby, generation | occurrence | production of the condensed water in an EGR valve | bulb can be suppressed, or the generated condensed water can be removed (dried). Therefore, it is possible to realize an internal combustion engine in which the introduction of EGR gas can be started early when the EGR valve is warmed early and condensed water does not exist around the EGR valve.

  According to the second and third inventions, when condensed water is generated or may be generated in the EGR valve, EGR is caused by the heat of the exhaust gas introduced using the EGR passage and the communication passage. The valve can be heated. Thereby, generation | occurrence | production of the condensed water in an EGR valve | bulb can be suppressed, or the generated condensed water can be removed (dried).

  According to the fourth aspect of the present invention, the flow of the exhaust gas that flows while touching the EGR valve when the open / close valve is opened while the EGR valve is closed is generated using a device that reduces the pressure in the exhaust passage. Can do.

  According to the fifth aspect of the present invention, the throttle valve that restricts the exhaust passage when the opening / closing valve is opened is used, and the exhaust gas flowing while touching the EGR valve when the opening / closing valve is opened while the EGR valve is closed is used. A flow can be generated.

  According to the sixth aspect of the invention, it is possible to form a flow path configuration in which when the open / close valve is opened, the exhaust gas flows from the exhaust passage into the communication passage and then flows into the EGR passage. Accordingly, when a general configuration in which an EGR cooler is provided in an exhaust passage upstream of the EGR gas flow with respect to the EGR valve is employed, when the EGR valve is heated, the EGR valve is reached before reaching the EGR valve. It is possible to avoid the exhaust gas from being cooled by the cooler. Thereby, the temperature of the exhaust gas that reaches the EGR valve when the EGR valve is heated can be kept high. For this reason, the warm-up property of the EGR valve can be ensured satisfactorily.

It is a figure for demonstrating schematically the system configuration | structure of the internal combustion engine in Embodiment 1 of this invention. FIG. 2 is a diagram illustrating a characteristic configuration around an LPL type EGR device illustrated in FIG. 1. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a figure for demonstrating the temperature estimation method of an EGR valve | bulb. It is a figure showing the effect of EGR valve warm-up operation. It is a figure showing other examples of the connection position of the EGR passage and the communicating passage to the exhaust passage. It is a figure showing the characteristic structure around the EGR apparatus in Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a figure showing the characteristic structure around the EGR apparatus in Embodiment 3 of this invention. It is a flowchart of the routine performed in Embodiment 3 of the present invention. It is a figure showing the modification of the structure around the EGR apparatus in Embodiment 3 of this invention.

Embodiment 1 FIG.
[System configuration of internal combustion engine]
FIG. 1 is a diagram schematically illustrating a system configuration of an internal combustion engine 10 according to Embodiment 1 of the present invention. The system of this embodiment includes an internal combustion engine (a spark ignition engine as an example) 10. An intake passage 12 and an exhaust passage 14 communicate with each cylinder of the internal combustion engine 10.

  An air cleaner 16 is attached in the vicinity of the inlet of the intake passage 12. Near the downstream of the air cleaner 16, an air flow meter 18 that outputs a signal corresponding to the flow rate of air sucked into the intake passage 12 and an intake air temperature sensor 20 that detects the temperature of the intake air are provided.

  A compressor 22 a of the turbocharger 22 is installed downstream of the air flow meter 18. The compressor 22a is integrally connected to a turbine 22b disposed in the exhaust passage 14 via a connecting shaft. An intercooler 24 for cooling the air compressed by the compressor 22a is provided downstream of the compressor 22a. An electronically controlled throttle valve 26 is provided downstream of the intercooler 24.

  Various catalysts for purifying exhaust gas are disposed in the exhaust passage 14 on the downstream side of the turbine 22b. Here, as an example, an upstream catalyst (S / C) 28 and a downstream catalyst (U / F) 30 that are both three-way catalysts are provided in order from the upstream side of the exhaust gas.

  The internal combustion engine 10 shown in FIG. 1 includes a low-pressure loop (LPL) type EGR device 32. The EGR device 32 includes an EGR passage 34 that connects the exhaust passage 14 downstream of the turbine 22b and the intake passage 12 upstream of the compressor 22a. The EGR passage 34 is provided with an EGR cooler 36 and an EGR valve 38 in order from the upstream side of the flow of EGR gas when introduced into the intake passage 12. The EGR cooler 36 is a water-cooled cooler provided to cool the EGR gas flowing through the EGR passage 34. The EGR valve 38 is provided for adjusting the amount of EGR gas recirculated to the intake passage 12 through the EGR passage 34. The valve body 38a (see FIG. 2) of the EGR valve 38 is warmed by the engine coolant. The temperature of the engine coolant supplied to the EGR cooler 36 is controlled to be higher than the dew point temperature of the exhaust gas (EGR gas) passing through the EGR cooler 36.

  The system of this embodiment is characterized by the configuration around the EGR device 32. This characteristic configuration will be described in detail with reference to FIG. Further, the system shown in FIG. 1 includes an ECU (Electronic Control Unit) 40. In addition to the air flow meter 18 and the intake air temperature sensor 20 described above, an internal combustion engine such as a crank angle sensor 42 for detecting the engine speed and a water temperature sensor 44 for detecting the engine coolant temperature is provided at the input portion of the ECU 40. Various sensors for detecting 10 driving states are connected. On the other hand, in addition to the throttle valve 26 and the EGR valve 38 described above, an output portion of the ECU 40 includes a fuel injection valve 46 for injecting fuel into the cylinder or the intake port of the internal combustion engine 10 and an air-fuel mixture in the cylinder. Various actuators for controlling the operation of the internal combustion engine 10 such as an ignition device 48 for igniting are connected. The ECU 40 controls the operation of the internal combustion engine 10 by operating various actuators in accordance with the outputs of the various sensors described above and a predetermined program.

[Characteristic configuration around the EGR apparatus in the first embodiment]
FIG. 2 is a diagram showing a characteristic configuration around the LPL type EGR device 32 shown in FIG. In the configuration shown in FIG. 2, the end portion of the EGR passage 34 on the exhaust passage 14 side is connected to the exhaust passage 14 at a portion between the upstream catalyst 28 and the downstream catalyst 30. In this example, the EGR valve 38 is provided at the end of the EGR passage 34 on the intake passage 12 side. However, the EGR valve 38 in the present invention is disposed at a position in the middle of the EGR passage 34. There may be.

  In the initial warm-up period after starting from the cold state, the EGR valve 38 is normally closed to maintain good combustion and condensate is easily generated. However, even if the EGR valve 38 is closed, the EGR passage 34 on the upstream side (exhaust passage 14 side) of the EGR gas flow with respect to the EGR valve 38 is filled with the exhaust gas due to exhaust pulsation. Has occurred. For this reason, dew condensation may occur when moisture in the exhaust gas touches the cold EGR valve 38. In this way, when the EGR valve 38 is closed and cold, condensed water can be generated on the valve surface of the EGR valve 38 on the exhaust passage 14 side and in the vicinity thereof.

  If the EGR valve 38 is opened and EGR gas is introduced without any consideration for the generation of condensed water in the EGR valve 38 as described above, this condensed water flows into the intake passage 12. As a result, there is a concern that corrosion of intake system parts may occur. Further, when the EGR gas is introduced into the intake passage 12 upstream of the compressor 22a as in the internal combustion engine 10 of the present embodiment, the wear (erosion) of the compressor 22a due to the collision of condensed water as well as the corrosion of the compressor 22a. ) May occur. On the other hand, when the introduction of EGR gas is prohibited until the condensed water in the EGR valve 38 disappears due to the complete warming up of the internal combustion engine 10, it takes a lot of time to remove (dry) the condensed water by the complete warming up. Therefore, the fuel efficiency effect due to the introduction of EGR gas cannot be brought out during that time.

  Therefore, in the present embodiment, in order to warm the EGR valve 38 at an early stage so that the introduction of EGR gas in the state where condensed water does not exist around the EGR valve 38 can be accelerated, the communication path 50 shown in FIG. And an opening / closing valve 52. The communication passage 50 connects the EGR passage 34 directly above the EGR valve 38 in the EGR gas flow direction and the exhaust passage 14 on the downstream side of the downstream catalyst 30. The open / close valve 52 is installed in the communication path 50 in order to open and close the communication path 50. The on-off valve 52 is electrically connected to the ECU 40 described above.

  The connection position 50 a between the communication passage 50 and the exhaust passage 14 is interposed between the EGR passage 34 and the connection position 34 a between the exhaust passage 14 and the downstream side catalyst 30. As a result, the communication passage 50 uses the pressure loss of the downstream side catalyst 30 and the exhaust passage 14 at a position where the pressure difference with respect to the pressure in the exhaust passage at the connection position 34a of the EGR passage 34 is generated (connection position 50a). It can be said that it is connected to. In other words, in the exhaust passage 14, the downstream side catalyst 30 as a device for reducing the pressure in the exhaust passage is disposed at a portion between the connection position 34 a of the EGR passage 34 and the connection position 50 a of the communication passage 50. .

  In the configuration described above, by opening the on-off valve 52 when the EGR valve 38 is cold, the EGR passage 34 and the communication passage 50 are sequentially passed by the part of the exhaust gas flowing through the exhaust passage 14 to the downstream side. An exhaust gas flow returning to the exhaust passage 14 on the downstream side of the catalyst 30 is formed. As described above, the connection position between the communication passage 50 and the EGR passage 34 is a position immediately above the EGR valve 38 in the EGR gas flow direction (when the EGR gas is introduced). As a result, when the exhaust gas flows from the EGR passage 34 toward the communication passage 50, the exhaust gas flows while touching the EGR valve 38. As a result, the EGR valve 38 can be heated by the heat of the exhaust gas. More specifically, the heat of the exhaust gas continuously flowing so as to always touch the EGR valve 38 is used as compared with the case of using the heat of the exhaust gas that intermittently arrives at the position of the EGR valve 38 due to the exhaust pulsation. Therefore, the EGR valve 38 can be warmed up early. Thereby, generation | occurrence | production of condensed water can be suppressed or the generated condensed water can be removed (dried).

[Characteristic control of the first embodiment]
According to the configuration described above, the open EGR valve 38 can be warmed quickly by opening the on-off valve 52 while the EGR valve 38 is closed. Therefore, in the present embodiment, when the EGR valve 38 is closed, when the EGR valve 38 is or is likely to generate condensed water, the opening / closing valve 52 is controlled to be opened. More specifically, the temperature of the EGR valve 38 is estimated, and when the estimated temperature of the EGR valve 38 is equal to or lower than the predetermined value X1, the opening / closing valve 52 is provided on condition that the engine coolant temperature THW satisfies the predetermined condition. Control (EGR valve warm-up operation) to open.

  FIG. 3 is a flowchart showing a control routine executed by the ECU 40 in order to realize the characteristic control of the first embodiment of the present invention. This routine is started at the time of cold start and is repeatedly executed every predetermined control cycle. Further, it is assumed that the EGR valve 38 is closed during a cold start.

In the routine shown in FIG. 3, the ECU 40 calculates the EGR valve estimated temperature in step 100. Here, as an example, the estimated EGR valve temperature is calculated by a function of intake air temperature THA, engine coolant temperature THW, and time. FIG. 4 is a diagram for explaining a temperature estimation method of the EGR valve 38. As shown in FIG. 4, the ECU 40 stores a map in which the base value _Teo of the temperature of the EGR valve 38 is determined based on the relationship between the intake air temperature THA and the engine coolant temperature THW. The base value T _eo here is a steady temperature of the EGR valve 38 when the intake air temperature THA and the engine coolant temperature THW are respectively arbitrary temperatures.

In this step 100, a value T _eo corresponding to the intake air temperature THA detected by the intake air temperature sensor 20 and the engine coolant temperature THW detected by the water temperature sensor 44 is acquired with reference to a map as shown in FIG. The Based on this value T _eo , the current temperature T _n of the EGR valve 38 that changes with a time delay under the influence of changes in the intake air temperature THA and the engine coolant temperature THW according to the equation (1). Is calculated. In Equation (1), T _n-1 is the previous value of the temperature of the EGR valve 38, and k is a preset annealing coefficient (0 <k <1). It is assumed that the water temperature sensor 44 measures the engine coolant temperature THW at a position correlated with the engine coolant temperature in the valve body 38a.

Next, the ECU 40 proceeds to step 102 and determines whether or not the EGR valve estimated temperature T _n is equal to or less than a predetermined value X1. The predetermined value X1 is a temperature at which condensation starts to occur in the EGR valve 38 (that is, a dew point temperature of exhaust gas in the vicinity of the EGR valve 38). By the processing in step 102, it is determined whether or not condensed water is generated in the EGR valve 38 or there is a possibility that it will be generated.

  If the determination in step 102 is not satisfied, the ECU 40 proceeds to step 104 and closes the open / close valve 52 or maintains the closed state. That is, in this case, the EGR valve warm-up operation is not executed. On the other hand, if the determination in step 102 is satisfied, the ECU 40 proceeds to step 106 and determines whether or not the engine coolant temperature THW is higher than a predetermined value X2. It is assumed that the water temperature sensor 44 measures the engine coolant temperature THW at a position that also correlates with the engine coolant temperature in the EGR cooler 36. The predetermined value X2 corresponds to the value of the engine coolant temperature THW detected by the water temperature sensor 44 when the engine coolant temperature in the EGR cooler 36 is the dew point temperature of the exhaust gas near the EGR cooler 36.

  If the determination in step 106 is not established, the ECU 40 proceeds to step 104 and does not execute the EGR valve warm-up operation. On the other hand, when the determination in step 106 is established, the ECU 40 proceeds to step 108 and executes an EGR valve warm-up operation (that is, opens or closes the opening / closing valve 52).

  According to the routine shown in FIG. 3 described above, when the EGR valve estimated temperature is equal to or lower than the predetermined value X1, it is determined that condensed water is generated or possibly generated in the EGR valve 38. The EGR valve warm-up operation is executed on condition that the determination in step 106 is satisfied. As a result, the EGR valve 38 can be warmed early and introduction of EGR gas can be started early in the state where condensed water does not exist around the EGR valve 38.

  Further, according to the above routine, the EGR valve is provided on condition that the engine coolant temperature in the EGR cooler 36 is determined to be higher than the dew point of the EGR gas because the engine coolant temperature is higher than the predetermined value X2. Execution of warm-up operation is permitted. Thus, the exhaust gas can be introduced around the EGR valve 38 for heating the EGR valve 38 while preventing the condensed water from being generated when the exhaust gas passes through the EGR cooler 36. However, the implementation of the EGR valve warm-up operation in the present invention is not necessarily limited to the one accompanied with the determination condition of the engine coolant temperature.

  FIG. 5 is a diagram showing the effect of the EGR valve warm-up operation. As shown in FIG. 5, the temperature of the EGR valve 38 at the cold start (more specifically, the surface of the umbrella portion upstream of the EGR gas flow) is controlled by controlling the opening / closing valve 52 for the warm-up operation of the EGR valve. It can be seen that the (temperature) rises earlier than when the control is not performed. It can also be seen that this control shortens the time required for the temperature of the EGR valve 38 to reach the dew point temperature of the EGR gas. Thus, according to this control, the warm-up property of the EGR valve 38 can be improved.

  By the way, in the first embodiment described above, the EGR passage 34 and the communication passage are arranged such that the downstream catalyst 30 is interposed in the exhaust passage 14 between the connection position 34a of the EGR passage 34 and the connection position 50a of the communication passage 50. 50 is configured. However, the example of using the pressure loss in the equipment such as the downstream side catalyst 30 in order to sufficiently secure the exhaust gas flow rate during the EGR valve warm-up operation is not limited to the above example. For example, FIG. The configuration shown in FIG.

  FIG. 6 is a diagram illustrating another example of the connection positions of the EGR passage and the communication passage with respect to the exhaust passage. In FIG. 6, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted or simplified. The EGR device 60 shown in FIG. 6 is different from the EGR device 32 shown in FIG. 2 in that the EGR passage 62 is connected to the exhaust passage 14 upstream of the turbine 22b. Further, the configuration shown in FIG. 6 is different from the configuration shown in FIG. 2 in that the communication passage 64 is connected to the exhaust passage 14 downstream of the turbine 22b (and upstream of the upstream catalyst 28). doing.

  As described above, in the configuration shown in FIG. 6, the EGR passage 62 and the communication passage 64 are arranged such that the turbine 22b is interposed in the exhaust passage 14 between the connection position 62a of the EGR passage 62 and the connection position 64a of the communication passage 64. Is configured. That is, in this example, the pressure loss of the turbine 22b is used for the EGR valve warm-up operation. As described above, the EGR device that is the subject of the present invention is not limited to the LPL type EGR device such as the EGR device 32 described above, and may be a high-pressure loop (HPL) type. In this example, the connection position 64 a of the communication path 64 is the exhaust passage 14 upstream of the upstream catalyst 28, but the connection position 64 a of the communication path 64 is the upstream catalyst 28 and the downstream catalyst 30. It may be a portion between the downstream catalyst 30 and the downstream portion of the downstream catalyst 30. As described above, a plurality of devices may be interposed in the exhaust passage 14 between the connection positions 62a and 64a. In addition, such a device may be other than the three-way catalyst and the turbine as long as the pressure in the exhaust passage can be lowered and a pressure difference can be appropriately generated between the connection positions 62a and 64a. For example, an exhaust purification catalyst other than a three-way catalyst, or a particulate filter for collecting particulate matter contained in exhaust gas may be used.

  In the first embodiment described above, the “control means” according to the second aspect of the present invention is implemented when the ECU 40 executes a series of processes shown in FIG.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. 7 and FIG.

[Characteristic configuration around the EGR apparatus in the second embodiment]
FIG. 7 is a diagram showing a characteristic configuration around the EGR device 32 according to the second embodiment of the present invention. In FIG. 7, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted or simplified. In the configuration shown in FIG. 7, the communication passage 70 is connected to the exhaust passage 14 at a portion between the upstream catalyst 28 and the downstream catalyst 30 similarly to the EGR passage 34, and the throttle valve 72 is connected to the exhaust passage 14. Is different from the configuration shown in FIG. More specifically, the throttle valve 72 is installed in the exhaust passage 14 at a portion between the connection position 34 a of the EGR passage 34 and the connection position 70 a of the communication passage 70. The throttle valve 72 is configured to be able to change the opening degree by the ECU 40 described above.

  In this configuration, the pressure difference between the front and rear of the open / close valve 52 is not secured by using pressure loss of a three-way catalyst or the like, but the EGR valve warming is performed using the throttle valve 72 provided between the two connection positions 34a and 70a. By restricting the exhaust passage 14 during machine operation, a pressure difference before and after the opening / closing valve 52 (pressure difference between the connection positions 34a and 70a) is secured.

[Characteristic control of the second embodiment]
FIG. 8 is a flowchart showing a control routine executed by the ECU 40 in order to realize the characteristic control of the second embodiment of the present invention. In FIG. 8, the same steps as those shown in FIG. 3 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 8, when the determination in step 106 is satisfied, that is, when the condition for executing the EGR valve warm-up operation is satisfied, the ECU 40 proceeds to step 200 and executes the EGR valve warm-up operation. . The EGR valve warm-up operation in this routine includes not only an operation of opening the opening / closing valve 52 but also an operation of restricting the exhaust flow by the throttle valve 72. Specifically, the throttle valve 72 is controlled to an opening degree that provides a pressure difference before and after the on-off valve 52 for obtaining an exhaust gas flow rate required for heating the EGR valve 38.

  Also by the routine shown in FIG. 8 described above, the introduction of EGR gas can be started early when the EGR valve 38 is warmed early and condensed water does not exist around the EGR valve 38.

In the second embodiment described above, the throttle valve 72 corresponds to the “predetermined actuator” in the first invention.
In the second embodiment described above, the “control means” according to the second aspect of the present invention is implemented when the ECU 40 executes a series of processes of the routine shown in FIG.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. 9 and FIG.

[Characteristic configuration around the EGR apparatus in the third embodiment]
FIG. 9 is a diagram showing a characteristic configuration around the EGR device 32 according to the third embodiment of the present invention. In FIG. 9, the same components as those shown in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted or simplified. The configuration shown in FIG. 9 is different from the configuration shown in FIG. 7 in the following points. That is, the communication path 80 in this configuration is such that the connection position 80a of the communication path 80 is upstream of the flow of exhaust gas in the exhaust passage 14 than the connection position 34a of the EGR path 34, and the upstream catalyst 28 and the downstream catalyst. 30 is configured to be connected to the exhaust passage 14 at a portion between the two. The throttle valve 72 is installed in the exhaust passage 14 at a portion between the connection position 80 a of the communication passage 80 and the connection position 34 a of the EGR passage 34.

  In the case of the configuration shown in FIG. 7 (Embodiment 2), when the EGR valve 38 is closed and the open / close valve 52 is opened with the exhaust flow being throttled by the throttle valve 72, the exhaust gas A flow path configuration is realized in which a part of the refrigerant flows into the EGR passage 34 from the exhaust passage 14 and then returns to the exhaust passage 14 through the communication passage 70. As is the case with the configuration shown in FIG. 7, the EGR cooler is usually disposed in the EGR passage at a portion upstream of the EGR gas flow from the EGR valve. Therefore, in the configuration shown in FIG. 7, the exhaust gas is cooled by the EGR cooler 36 before reaching the EGR valve 38 during the EGR valve warm-up operation, and the warm-up performance of the EGR valve 38 may deteriorate. .

  On the other hand, in the case of this configuration, when the opening / closing valve 52 is opened with the EGR valve 38 closed and the exhaust flow restricted by the throttle valve 72, a part of the exhaust gas is exhausted. A flow path configuration opposite to the above is realized in which the air flows from the passage 14 into the communication passage 80 and then returns to the exhaust passage 14 through the EGR passage 34. As a result, the exhaust gas after heating the EGR valve 38 passes through the EGR cooler 36. Accordingly, the temperature of the exhaust gas reaching the EGR valve 38 is kept high when the EGR valve is warmed up without changing the basic configuration in which the EGR cooler 36 is arranged upstream of the EGR valve 38 from the EGR valve 38. Will be able to. For this reason, the warm-up property of the EGR valve 38 can be ensured satisfactorily. Further, as a measure for keeping the temperature of the exhaust gas reaching the EGR valve 38 at a high level, unlike the present configuration, it is also conceivable to configure a flow path configuration that does not involve any EGR cooler. However, compared to such a configuration, according to the present configuration, exhaust heat recovery can be performed by the EGR cooler 36 while the EGR valve 38 is heated in the cold state, so that an early warm-up effect of the engine coolant can be obtained.

[Characteristic control of Embodiment 3]
FIG. 10 is a flowchart showing a control routine executed by the ECU 40 in order to realize the characteristic control of the third embodiment of the present invention. As shown in FIG. 10, this routine is the same as the routine shown in FIG. 8 except that the processing of step 106 is not provided. This is because, as described above, when the configuration shown in FIG. 9 is adopted, the exhaust gas is not cooled by the EGR cooler 36 before reaching the EGR valve 38 when the EGR valve is warmed up. is there.

  In the third embodiment described above, an example in which the throttle valve 72 is provided in the exhaust passage 14 between the connection position 80a of the communication passage 80 and the connection position 34a of the EGR passage 34 has been described. However, the example of the communication path configured such that the connection position of the communication path becomes the exhaust passage 14 on the upstream side of the connection position of the EGR path is not limited to the above, and for example, the configuration shown in FIG. It may be.

  FIG. 11 is a diagram illustrating a modification of the configuration around the EGR device 32 according to the third embodiment of the present invention. In FIG. 11, the same components as those shown in FIG. 9 are denoted by the same reference numerals, and the description thereof is omitted or simplified. The configuration shown in FIG. 11 is shown in FIG. 9 in that the throttle valve 72 is not provided and the connection position 90a of the communication passage 90 is the exhaust passage 14 upstream of the upstream catalyst 28. It is different from the configuration. As exemplified by the configuration shown in FIG. 11, even when the connection position of the communication path is configured to be the exhaust path 14 upstream of the connection position of the EGR path, the exhaust path is replaced with the throttle valve 72. You may make it utilize the at least 1 apparatus (three-way catalyst etc.) which drops an internal pressure.

  In the third embodiment described above, the “control means” according to the second aspect of the present invention is implemented when the ECU 40 executes a series of processes of the routine shown in FIG.

  In the above-described first to third embodiments and their modifications, the EGR device 32 or 60 provided with the EGR cooler 36 in the EGR passage 34 or 62 has been described as an example. The present invention can also be applied to a configuration in which an EGR cooler is not provided in the EGR passage.

  Further, in the above-described first to third embodiments and their modifications, a turbocharger 22 that uses exhaust energy as a driving force is taken as an example of a turbocharger having a compressor 22a that supercharges intake air. Explained. However, the supercharger in the present invention is not limited to the turbocharger. That is, the compressor according to the present invention may use, for example, the power from the crankshaft of the internal combustion engine as a driving force as long as the intake air is supercharged, or an electric motor as the driving force. It may be used.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 14 Exhaust passage 16 Air cleaner 18 Air flow meter 20 Intake temperature sensor 22 Turbocharger 22a Compressor 22b Turbine 24 Intercooler 26 Throttle valve 28 Upstream catalyst 30 Downstream catalyst 32, 60 EGR device 34, 62 EGR passage 34a, 62a Connection position 36 between EGR passage and exhaust passage 36 EGR cooler 38 EGR valve 38a Valve body 40 ECU (Electronic Control Unit)
42 Crank angle sensor 44 Water temperature sensor 46 Fuel injection valve 48 Ignition device 50, 64, 70, 80, 90 Communication path 50a, 64a, 70a, 80a, 90a Connection position 52 between communication path and exhaust path 52 Open / close valve 72 Throttle valve

Claims (6)

A compressor for supercharging intake air;
An EGR passage connecting an intake passage and an exhaust passage upstream of the compressor;
An EGR valve that is provided in an end portion of the EGR passage on the side of the intake passage or in the middle of the EGR passage, and adjusts the flow rate of EGR gas flowing through the EGR passage;
A communication passage connecting the EGR passage and the exhaust passage;
An opening and closing valve for opening and closing the communication path,
The communication passage is connected to the EGR passage at a position immediately above the EGR valve in the EGR gas flow direction, and a pressure difference with respect to the pressure in the exhaust passage occurs at the connection position of the EGR passage and the exhaust passage. The internal combustion engine is connected to the exhaust passage at a position where the pressure difference is present or a position where the pressure difference is caused by the operation of a predetermined actuator.   2. The control device according to claim 1, further comprising control means for opening the opening / closing valve when condensed water is generated or is likely to be generated in the EGR valve in a state where the EGR valve is closed. The internal combustion engine described in 1.   3. The internal combustion engine according to claim 2, wherein the case where condensed water is generated or possibly generated in the EGR valve is a case where the temperature of the EGR valve becomes a predetermined value or less. organ.   In the exhaust passage, at least one device for lowering the pressure in the exhaust passage is interposed between the connection position of the EGR passage and the exhaust passage and the connection position of the communication passage and the exhaust passage. The internal combustion engine according to any one of claims 1 to 3, wherein the internal combustion engine is provided.   In the exhaust passage, the exhaust passage is throttled when the opening / closing valve is opened at a position between the connection position of the EGR passage and the exhaust passage and the connection position of the communication passage and the exhaust passage. The internal combustion engine according to any one of claims 1 to 3, wherein a throttle valve is arranged as the predetermined actuator. An EGR cooler that is arranged in the EGR passage upstream of the EGR gas flow from the EGR valve and cools the EGR gas flowing through the EGR passage;
The connection position between the communication passage and the exhaust passage is provided upstream of the flow of exhaust gas in the exhaust passage from the connection position between the EGR passage and the exhaust passage. Item 6. The internal combustion engine according to any one of Items 1 to 5.

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