JP5365787B2 - Engine exhaust gas recirculation device - Google Patents

Description

  The present invention relates to an engine exhaust gas recirculation device, and more particularly to an engine exhaust gas recirculation device including a first EGR passage provided with an EGR cooler and a second EGR passage bypassing the EGR cooler.

Conventionally, an engine exhaust gas recirculation device that performs a cooled EGR by providing an EGR cooler in an exhaust gas recirculation passage is known (see, for example, Patent Document 1).
In the exhaust gas recirculation device as described in Patent Document 1, it is generally possible to reduce NOx in the exhaust gas by executing the cooled EGR, but at a low cooling water temperature at which the engine is not warmed. When the cooled EGR is executed, there is a problem that CO and HC in the exhaust gas increase.

  On the other hand, an exhaust gas recirculation device having an exhaust gas recirculation passage (first EGR passage) provided with an EGR cooler and a bypass passage (second EGR passage) bypassing the EGR cooler is known. In such an exhaust gas recirculation device, hot EGR that recirculates exhaust gas through the second EGR passage is executed until the engine is warmed, and when the engine is warmed, the second EGR passage is switched to the first EGR passage to perform cooled EGR. Is done.

  That is, if the cooled EGR is performed to reduce NOx when the engine is at a low cooling water temperature that is not warmed, CO and HC in the exhaust gas increase. Therefore, at the low cooling water temperature, the second EGR passage is opened. The hot EGR for recirculating the exhaust gas is performed. As a result, the engine warms up quickly while obtaining even a little NOx reduction effect. Since the generation of HC and CO does not become a problem when the engine is warmed, the cooled EGR is executed to increase the NOx reduction effect.

  As described above, in the exhaust gas recirculation device including the first and second EGR passages, NOx can also be reduced while reducing HC and CO at the time of starting the engine.

Japanese Patent Laid-Open No. 2000-130266

However, in the exhaust gas recirculation device having the first and second EGR passages described above, the hot EGR is used instead of the cooled EGR until the engine is warmed, and therefore, an improvement for further improving the NOx reduction capability. Was desired.
Furthermore, in the exhaust gas recirculation device as described above, soot and the like contained in the exhaust gas accumulates on the wall surface of the passage portion of the EGR cooler with use, and as a result, the cooling efficiency of the EGR cooler gradually deteriorates. . For this reason, there was room for improvement in consideration of deterioration of the cooling efficiency of the EGR cooler.

  The present invention has been made to solve such a problem, and in an engine exhaust gas recirculation apparatus including a first EGR passage provided with an EGR cooler and a second EGR passage bypassing the EGR cooler, HC, CO, and An object of the present invention is to provide an engine exhaust gas recirculation device that further improves the NOx reduction capability.

In order to solve the above-described problems, the present invention provides a first EGR passage that recirculates part of exhaust gas discharged from an engine to an intake passage, and an EGR that is provided in the first EGR passage and cools the recirculated exhaust gas. A cooling efficiency acquisition means for acquiring the cooling efficiency of the EGR cooler in an engine exhaust gas recirculation device comprising a cooler and a second EGR passage that bypasses the EGR cooler and recirculates part of the exhaust gas to the intake passage; A cooling water temperature detecting means for detecting the cooling water temperature of the engine, and a switching control means for selectively switching the exhaust gas recirculation passage to one of the first EGR passage and the second EGR passage. , such that recirculates exhaust gas through the 2EGR passage only predetermined period immediately after engine start up, coolant temperature it above a predetermined switching temperature And switching the return passage to the 1EGR passage from the 2EGR passage, the switching control means, as the cooling efficiency calculated by the cooling efficiency obtaining means based on the parameter values associated with the travel distance of the vehicle in which the engine is mounted is low switching It is characterized by setting the temperature to a low temperature.

  In the present invention configured as described above, while the engine coolant temperature is lower than the switching temperature, the second EGR passage is selected and hot EGR is performed. Thereby, it is possible to suppress an increase in the generation amount of HC and CO by warming the engine at an early stage while obtaining the NOx reduction effect. When the coolant temperature of the engine becomes higher than the switching temperature, HC and CO do not become a problem, so the first EGR passage is selected and cooled EGR is performed. Thereby, the NOx reduction effect can be obtained.

Furthermore, in the present invention, the switching temperature is set to be low as the cooling efficiency of the EGR cooler decreases, and the switching from the hot EGR to the cooled EGR is accelerated, so that NOx, CO, and HC can be controlled regardless of the cooling efficiency of the EGR cooler. Both increases can be comprehensively suppressed.
In addition, since the cooling efficiency of the EGR cooler can be easily obtained without using a special sensor, the manufacturing cost of the apparatus can be suppressed.

In order to solve the above-described problem, the present invention provides a first EGR passage that recirculates a part of the exhaust gas discharged from the engine to the intake passage, and cools the exhaust gas that is recirculated provided in the first EGR passage. An engine exhaust gas recirculation device comprising an EGR cooler and a second EGR passage that bypasses the EGR cooler and recirculates part of the exhaust gas to the intake passage, and obtains cooling efficiency for obtaining the cooling efficiency of the EGR cooler And a ratio of the exhaust gas recirculation amount through the first EGR passage and the exhaust gas recirculation amount through the second EGR passage based on the cooling water temperature when the engine is started. and a adjustment control means for adjusting and controlling the adjustment control means may be a cooling water temperature is the same, the running of the vehicle in which the engine is mounted Is characterized by adjusting and controlling so as to increase the percentage of recirculation amount according 1EGR passage than when high when a low cooling efficiency calculated by the cooling efficiency obtaining means based on the associated parameter values away.

  In the present invention thus configured, the coolant temperature is adjusted by adjusting the ratio of the exhaust gas recirculation amount through the first EGR passage and the exhaust gas recirculation amount through the second EGR passage based on the engine coolant temperature. When the coolant temperature is low, the second EGR passage is selected and hot EGR is executed. When the cooling water temperature is high, the first EGR passage is selected and the cooled EGR is executed. When the cooling water temperature is between these values, the first EGR passage is executed. By adjusting the ratio of these reflux amounts using both the first and second EGR passages, it is possible to achieve both NOx reduction effects and HC and CO reduction effects.

  Furthermore, in the present invention, by increasing the ratio of the recirculation amount of the first EGR passage as the cooling efficiency of the EGR cooler is reduced, it is possible to comprehensively increase both NOx, CO, and HC regardless of the cooling efficiency of the EGR cooler. Can be suppressed.

Further , since the cooling efficiency of the EGR cooler can be easily obtained without using a special sensor, the manufacturing cost of the apparatus can be suppressed.

  According to the present invention, in the engine exhaust gas recirculation device including the first EGR passage provided with the EGR cooler and the second EGR passage provided with no EGR cooler, the ability to reduce HC, CO, and NOx can be further improved. .

1 is an overall view of an engine exhaust gas recirculation device in a first embodiment of the present invention. It is an exhaust-gas recirculation | reflux processing flow in 1st Embodiment of this invention. It is a graph showing the relationship between the travel distance and cooling efficiency in 1st Embodiment of this invention. It is a graph showing the relationship between the cooling efficiency in 1st Embodiment of this invention, and switching temperature. It is an exhaust gas recirculation | reflux processing flow in 2nd Embodiment of this invention. It is a graph showing the relationship between the cooling efficiency in 2nd Embodiment of this invention, and a cooling water temperature setting value.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.
First, an engine exhaust gas recirculation device according to a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, an engine exhaust gas recirculation device 1 according to an embodiment of the present invention includes an exhaust gas recirculation passage 10 for recirculating a part of exhaust gas of an engine 2 from an exhaust passage 3b to an intake passage 3a, And a control unit 20 that controls the flow path of the exhaust gas recirculation passage 10.

  In the intake passage 3a of the engine 2, an air cleaner 4, an intake throttle valve 5, an intake air amount sensor 6, an intake air temperature sensor 7, and an intake air pressure sensor 8 are arranged in this order from the upstream side. The intake air amount sensor 6, the intake air temperature sensor 7, and the intake pressure sensor 8 output detection signals to the control unit 20. The intake throttle valve 5 adjusts the amount of intake air that flows into the intake side of the engine 2.

  The exhaust gas recirculation passage 10 includes a first EGR passage 11 that communicates between the exhaust passage 3b and the intake passage 3a, and a second EGR passage 12 that communicates between the exhaust passage 3b and the intake passage 3a in the same manner as the first EGR passage 11. And an EGR cooler 13 attached to the first EGR passage 11, an EGR valve 14 attached to the reflux passage, and a control valve 15.

In the present embodiment, the second EGR passage 12 is configured to be branched in the middle so as to bypass the EGR cooler 13 provided in the first EGR passage 11.
The EGR cooler 13 is, for example, a water-cooled cooling device, and cools the recirculated exhaust gas by heat exchange between the cooling medium that passes through the EGR cooler and the exhaust gas that recirculates through the first EGR passage 11.

  The EGR valve 14 is provided closer to the intake passage 3a than the junction of the first EGR passage 11 and the second EGR passage 12, and is recirculated through the exhaust gas recirculation passage 10 based on a control signal from the control unit 20. Adjust the exhaust gas recirculation amount. That is, the EGR valve 14 can adjust the recirculation amount of the exhaust gas of the engine 2 according to the opening degree.

  The control valve 15 is attached to the joining point of the first EGR passage 11 and the second EGR passage 12, and based on a control signal from the control unit 20, the amount of exhaust passing through the first EGR passage 11 and the second EGR passage 12 is controlled. The ratio is configured to be adjustable. In the present embodiment, the control valve 15 functions to selectively communicate either the first EGR passage 11 or the second EGR passage 12 to the intake passage 3a based on the control signal.

  More specifically, the control valve 15 causes the second EGR passage 12 to communicate with the intake passage 3a when the engine is started. As a result, hot EGR is executed when the engine is started. The control valve 15 switches the passage from the second EGR passage 12 to the first EGR passage 11 after the engine 2 has warmed to a predetermined temperature or higher. Thereby, the cooled EGR is executed during normal operation.

The control unit 20 is an ECU provided in the vehicle, receives signals from various sensors, and performs switching control of the EGR valve 14 and the control valve 15 based on these signals.
In order to perform this switching control, the control unit 20 includes a cooling water temperature sensor 21 (cooling water temperature detecting means) of the engine 2, an engine rotation speed sensor 22, an accelerator opening sensor 23, a vehicle wheel rotation speed sensor 24, and the like. Receive various signals. The control unit 20 detects the operating state of the engine 2 based on these signals.

The cooling water temperature sensor 21 outputs a cooling water temperature signal representing the cooling water temperature Tw of the engine 2 to the control unit 20.
The engine rotation speed sensor 22 outputs an engine rotation speed signal representing the engine rotation speed Ne to the control unit 20.
The accelerator opening sensor 23 outputs an accelerator opening signal representing the accelerator opening θa to the control unit 20.
The wheel rotation speed sensor 24 outputs a wheel rotation speed signal representing the wheel rotation speed Nw to the control unit 20.

  As described above, as the EGR cooler 13 is used, soot and the like adhere to the inner surface, and the heat exchange efficiency gradually decreases. For this reason, the cooling efficiency gradually decreases. In the present embodiment, as described below, a favorable NOx reduction effect can be obtained by controlling the switching timing from the second EGR passage 12 to the first EGR passage 11 in accordance with such a decrease in cooling efficiency. It is configured to be possible.

  That is, if only the NOx reduction effect is taken into consideration, the cooled EGR may be executed from the start of the engine start, but if the cooled EGR is performed immediately after the start of the engine start, the generation of HC and CO becomes a problem. Here, the fact that the cooling efficiency of the EGR cooler 13 decreases means that the temperature of the exhaust gas to be recirculated is less likely to decrease even if the cooled EGR is performed by recirculation in the first EGR passage 11. means. In other words, after a certain period of use, compared to the beginning of use, the temperature of the recirculated exhaust gas is less likely to decrease due to the cooled EGR. It becomes difficult.

  Therefore, in this embodiment, when the engine coolant temperature reaches a fixed switching temperature value, the EGR passage is not switched, but the switching temperature value is decreased and the switching timing is advanced as the EGR cooling efficiency is decreased. As a result, the NOx reduction effect is improved.

Next, the operation of the engine exhaust gas recirculation apparatus 1 according to the first embodiment of the present invention will be described based on the exhaust gas recirculation process flow of FIG. The control unit 20 repeatedly performs the process shown in FIG. 2 every predetermined time.
First, the control unit 20 reads signals representing the engine rotational speed Ne, the accelerator opening θa, the coolant temperature Tw, and the wheel rotational speed Nw received from each sensor (step SA1).

The control unit 20 calculates the vehicle travel distance D based on the read wheel rotation speed Nw and the vehicle structure specification (step SA2). The vehicle travel distance D is a distance traveled in a state where the EGR cooler 13 is mounted on the vehicle.
The control unit 20 as the cooling efficiency acquisition means stores data representing the relationship between the vehicle travel distance D and the cooling efficiency η of the EGR cooler 13 shown in FIG. The cooling efficiency η is calculated (step SA3).

  That is, in the present embodiment, the cooling efficiency η of the EGR cooler 13 is estimated from the vehicle travel distance D. However, the present invention is not limited to this, and the cooling efficiency η is estimated from the usage history of the first EGR passage 11 in which the EGR cooler 13 is provided (for example, the accumulated time during which the first EGR passage 11 is used as the EGR passage). May be. Further, temperature sensors may be provided on the upstream and downstream sides of the EGR cooler 13, respectively, and the cooling efficiency η may be calculated based on the temperature of the exhaust gas recirculation gas detected by these temperature sensors, and updated and stored in the internal memory. .

Further, the control unit 20 stores data representing the relationship between the cooling efficiency η and the switching temperature setting value Tws shown in FIG. 4 in the internal memory, and the switching temperature setting value Tws is calculated from this data and the calculated cooling efficiency η. Calculate (step SA4).
The switching temperature set value Tws is the switching temperature of the EGR passage. When the coolant temperature Tw of the engine 2 is equal to or higher than the set value Tws, the set value Tws can secure stable combustion even if the cooled EGR is executed, and the generation of HC and CO is a problem. It is set to a value that does not occur.

  As shown in FIG. 4, when the cooling efficiency η is high, the set value Tws is also high, and the period during which hot EGR is executed after the engine is started becomes long. However, when the cooling efficiency η is lowered, the set value Tws is accordingly increased. And the hot EGR implementation period is gradually shortened.

Further, the control unit 20 calculates the required engine torque Te based on the read engine rotational speed Ne and accelerator opening degree θa (step SA5).
Next, the control unit 20 determines whether or not the read current coolant temperature Tw is equal to or higher than the coolant temperature set value Tws (step SA6).

  When the cooling water temperature Tw is not equal to or higher than the cooling water temperature set value Tws (step SA6; No), the engine 2 is not sufficiently warmed immediately after the start of starting, and if the cooled EGR is executed in this state, generation of HC and CO is a problem. Therefore, the control unit 20 as the switching control means controls the flow direction of the control valve 15 so that the exhaust gas is recirculated (hot EGR) through the second EGR passage 12 (step SA8).

  On the other hand, when the cooling water temperature Tw is equal to or higher than the cooling water temperature set value Tws (step SA6; Yes), the engine 2 is sufficiently warm, and even if the cooled EGR is executed in this state, generation of HC and CO is a problem. Therefore, the control unit 20 as the switching control unit controls the flow direction of the control valve 15 so that the exhaust gas is recirculated (cooled EGR) through the first EGR passage 11 (step SA7). As described above, the hot EGR is executed only for a predetermined period immediately after the start of the engine 2 and once switched to the cooled EGR, the cooled EGR is maintained in the normal state.

  And the control part 20 adjusts the valve opening degree of the EGR valve 14 based on the engine speed Ne and the calculated request | required engine torque Te, and controls recirculation | reflux amount (step SA9).

  As described above, in the present embodiment, after the engine is started, when the temperature of the engine 2 or the cooling water temperature Tw reaches the predetermined switching temperature setting value Tws, the control valve 15 switches from the hot EGR to the cooled EGR. The EGR passage is selectively switched from the second EGR passage 12 to the first EGR passage 11.

  At this time, it is configured such that the switching time can be advanced by setting the switching temperature set value Tws to be low as the cooling efficiency η of the EGR cooler 13 is deteriorated. Considering the decrease in the cooling efficiency η, it is possible to obtain the NOx reduction effect at an early stage without deteriorating HC and CO by advancing the switching timing to the cooled EGR.

Next, an exhaust gas recirculation process flow of the engine exhaust gas recirculation apparatus 1 according to the second embodiment of the present invention will be described with reference to FIG.
In the first embodiment, the control unit 20 performs control so as to selectively switch between hot EGR and cooled EGR, that is, to selectively switch the EGR path between the first EGR path 11 and the second EGR path 12. The valve 15 was controlled. On the other hand, in the second embodiment, in the switching control from hot EGR to cooled EGR, the control unit 20 sets the ratio of the respective recirculation amounts passing through the first EGR passage 11 and the second EGR passage 12 to the cooling water temperature Tw. The control valve 15 is controlled so as to change accordingly.

In the process of FIG. 5, steps SB1 to SB3 are the same as steps SA1 to SA3 of FIG.
The control unit 20 stores data representing the relationship between the cooling efficiency η and the cooling water temperature set values Tw1 and Tw2 shown in FIG. 6 in the internal memory, and the first temperature set value is calculated from this data and the calculated cooling efficiency η. Tw1 and second temperature set value Tw2 are calculated, respectively, and the ratio of the recirculation amount by the second EGR passage 12 at the current cooling water temperature Tw is set (step SB4).

  The first temperature set value Tw1 is a switching start temperature from hot EGR to cooled EGR, and the second temperature set value Tw2 is a switching end temperature (Tw1 <Tw2). That is, at a certain cooling efficiency η, when the engine is started, the recirculation amount through the second EGR passage 12 is 100% and the recirculation amount through the first EGR passage 11 is 0% until the cooling water temperature Tw reaches the first temperature set value Tw1. Is set.

When the cooling water temperature Tw is between the first temperature setting value Tw1 and the second temperature setting value Tw2, the recirculation amount by the second EGR passage 12 as the cooling water temperature Tw approaches the second temperature setting value Tw2. Decreases, and the control unit 20 controls the control valve 15 so that the recirculation amount through the first EGR passage 11 increases. When the cooling water temperature Tw reaches the second temperature set value Tw2, the recirculation amount through the second EGR passage 12 becomes 0%, and the recirculation amount through the first EGR passage 11 becomes 100%.
Therefore, by setting the cooling water temperature set values Tw1 and Tw2 based on the data shown in FIG. 6, even if the cooling water temperature Tw is the same, the amount of recirculation by the first EGR passage 11 is higher when the cooling efficiency η is low than when it is high. And the ratio of the amount of recirculation through the second EGR passage 12 decreases.

  In the present embodiment, the control unit 20 uses the first temperature set value Tw1 and the ratio of the recirculation amount of the second EGR passage 12 is 100% (the ratio of the recirculation amount of the first EGR passage 11 is 0%), and the second temperature set value Tw2. Thus, the ratio of the recirculation amount of the second EGR passage 12 is 0% (the recirculation amount ratio of the first EGR passage 11 is 100%), and the current cooling water temperature Tw is the first temperature set value Tw1 and the second temperature set value Tw2. By proportionally allocating, the ratio of the reflux amount of the second EGR passage 12 (and the ratio of the reflux amount of the first EGR passage 11) can be determined. Therefore, in the process of step SB4, the control unit 20 gradually increases the ratio of the recirculation amount from the first EGR passage 11 from 0% to 100% as the cooling water temperature Tw increases.

Further, the control unit 20 calculates the required engine torque Te based on the read engine rotational speed Ne and accelerator opening degree θa (step SB5).
Next, the control unit 20 determines whether or not the read current coolant temperature Tw is equal to or lower than the first temperature set value Tw1 (step SB6).

  When the coolant temperature Tw is equal to or lower than the first temperature set value Tw1 (step SB6; Yes), the engine 2 is not sufficiently warmed immediately after the start of starting, and generation of HC and CO occurs when the cooled EGR is executed in this state. Since it becomes a problem, the control part 20 as an adjustment control means controls the control valve 15 so that exhaust gas recirculates (hot EGR) through the 2nd EGR channel | path 12 (step SB7).

  On the other hand, when the coolant temperature Tw is not equal to or lower than the first temperature set value Tw1 (step SB6; No), the control unit 20 determines whether or not the current coolant temperature Tw is equal to or higher than the second temperature set value Tw2. (Step SB8).

  When the coolant temperature Tw is not equal to or higher than the second temperature set value Tw2 (step SB8; No), the coolant temperature Tw is greater than the first temperature set value Tw1 and less than the second temperature set value Tw2 (Tw1 <Tw <Tw2). Yes, the engine 2 is in a state where it is not sufficient but is warmed to some extent, and in order to obtain the NOx reduction effect as early as possible without deteriorating HC and CO so much, the control unit 20 as the adjustment control means includes a control valve 15 And the ratio of the recirculation amount from the second EGR passage 12 is changed between 0% and 100% in accordance with the cooling water temperature Tw so as to be the EGR passage ratio set in the process of step SB4 (step SB4). SB10).

  On the other hand, if the cooling water temperature Tw is equal to or higher than the second temperature set value Tw2 (step SB8; Yes), the engine 2 is sufficiently warm, and even if the cooled EGR is executed completely in this state, HC and CO are generated. Therefore, the control unit 20 as the adjustment control means controls the control valve 15 so that the ratio of the recirculation amount by the first EGR passage 11 becomes 100% (step SB9).

Then, after setting the flow path ratio, the control unit 20 adjusts the valve opening of the EGR valve 14 based on the engine rotational speed Ne and the calculated required engine torque Te to control the recirculation amount (step SB11). ).
As described above, in the present embodiment, after the engine is started, when the temperature of the engine 2 or the coolant temperature Tw reaches the predetermined first temperature set value Tw1, switching from the hot EGR to the cooled EGR is started. When the second temperature set value Tw2 is reached, the control valve 15 is switched so as to completely shift to the cooled EGR.

  At this time, with the deterioration of the cooling efficiency η of the EGR cooler 13, the first temperature set value Tw1 and the second temperature set value Tw2 are set lower so that the switching time can be advanced. Considering the decrease in cooling efficiency η, the NOx reduction effect can be obtained earlier by advancing the switching timing to the cooled EGR.

DESCRIPTION OF SYMBOLS 1 Engine exhaust gas recirculation apparatus 2 Engine 3a Intake passage 3b Exhaust passage 4 Air cleaner 5 Intake throttle valve 6 Intake amount sensor 7 Intake temperature sensor 8 Intake pressure sensor 10 Exhaust gas recirculation passage 11 1st EGR passage 12 2nd EGR passage 13 EGR cooler 14 EGR Valve 15 Control valve 20 Control unit 21 Cooling water temperature sensor 22 Engine rotation speed sensor 23 Accelerator opening sensor 24 Wheel rotation speed sensor

Claims (2)

A first EGR passage that recirculates part of the exhaust gas discharged from the engine to the intake passage, an EGR cooler that is provided in the first EGR passage and cools the recirculated exhaust gas, and bypasses the EGR cooler to An engine exhaust gas recirculation device comprising: a second EGR passage that partially recirculates to the intake passage;
Cooling efficiency acquisition means for acquiring the cooling efficiency of the EGR cooler;
Cooling water temperature detecting means for detecting the cooling water temperature of the engine;
Switching control means for selectively switching the exhaust gas recirculation passage to one of the first EGR passage and the second EGR passage;
The switching control means causes the recirculation passage from the second EGR passage to the first EGR passage so that the exhaust gas is recirculated through the second EGR passage only during a predetermined period immediately after engine start. Switch to
The switching control means sets the switching temperature to a lower temperature as the cooling efficiency calculated by the cooling efficiency acquisition means is lower based on a parameter value related to a travel distance of a vehicle equipped with an engine. The engine exhaust gas recirculation device. A first EGR passage that recirculates part of the exhaust gas discharged from the engine to the intake passage, an EGR cooler that is provided in the first EGR passage and cools the recirculated exhaust gas, bypasses the EGR cooler, An engine exhaust gas recirculation device comprising: a second EGR passage that partially recirculates to the intake passage;
Cooling efficiency acquisition means for acquiring the cooling efficiency of the EGR cooler;
Cooling water temperature detecting means for detecting the cooling water temperature of the engine;
Adjustment control means for adjusting and controlling the ratio of the exhaust gas recirculation amount through the first EGR passage and the exhaust gas recirculation amount through the second EGR passage based on the cooling water temperature when starting the engine ;
The adjustment control means is high when the cooling efficiency calculated by the cooling efficiency acquisition means is low based on a parameter value related to the travel distance of the vehicle on which the engine is mounted even if the cooling water temperature is the same. An engine exhaust gas recirculation device that performs adjustment control so that the ratio of the recirculation amount through the first EGR passage is increased as compared with the time.

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