JP4911090B2 - EGR control device - Google Patents

Description

  The present invention relates to an EGR control device.

  Recently, an EGR (Exhaust Gas Recirculation) device is used as an effective means for reducing NOX, reducing emissions, improving fuel consumption, and the like. In addition, a vehicle (FFV: Flexible Fuel Vehicle) using a fuel mixed with alcohol has been developed, and an EGR device may be incorporated in such an FFV. Patent Document 1 discloses the EGR control when the EGR device is mounted on the FFV as described above. Specifically, control is performed to decrease the EGR amount as the alcohol concentration in the fuel is higher.

JP-A-5-106498

By the way, in the EGR device, when the moisture content in the exhaust gas (EGR gas) is large, condensation of moisture occurs in the EGR pipe. Condensed water generated in the EGR pipe may catch unburned components in the EGR gas and contribute to deposit formation. As described above, it is assumed that the generation of condensed water induces clogging of the EGR pipe due to the condensed water, and hinders the use of the EGR device, such as a reduction in efficiency of the EGR device. In particular, the alcohol fuel used for FFV has a high water generation amount compared to gasoline, and thus may generate water. For example, in the case of ethanol fuel, the same amount of air is consumed and almost equal, as is apparent from the following equation (1) showing the reaction equation of gasoline and equation (2) showing the reaction equation of ethanol fuel. when generating the reaction heat, the alcohol fuel moisture (H 2 _O) generated a large amount as compared to moisture (H 2 _O) generated amount of gasoline.

Formula (1)
C ₇ H _11.9 +9.975 (O ₂ + 3.785N ₂ )
→ 7CO ₂ + 5.95H ₂ O + 37.76N ₂ + 4.07MJ

Formula (2)
3.325C ₂ H ₅ OH + 9.975 (O ₂ + 3.785N ₂ )
→ 6.65CO ₂ + 9.975H ₂ O + 37.76N ₂ + 4.04MJ

  Furthermore, alcohol fuel has a higher theoretical air-fuel ratio than when gasoline is used, and as a result, the amount of fuel injection increases and the heat of vaporization also increases, so the exhaust temperature tends to be low. If the exhaust temperature is low, condensation of moisture tends to proceed.

  As described above, in the FFV, the EGR gas contains a lot of moisture itself, and the temperature tends to be low, so that the moisture is easily condensed, and clogging due to the condensed water in the EGR pipe is likely to occur.

  In Patent Document 1, no special measures are taken against such a tendency in FFV. Some EGR devices include an EGR cooler for cooling EGR gas, but as disclosed in Patent Document 1, the higher the alcohol concentration in the fuel, the lower the EGR amount, that is, the more the EGR device is introduced. When the control for reducing the amount of EGR gas is performed, excessive cooling is performed in the EGR cooler, which may promote the generation of condensed water. That is, if the amount of introduced EGR gas decreases with respect to an EGR cooler that exhibits a certain cooling performance, the temperature of the introduced EGR gas further decreases, and condensed water is likely to be generated. As a result, there is an increased risk of the EGR device having a reduced function.

  Then, this invention makes it a subject to provide the EGR control apparatus which can suppress the clogging resulting from the condensed water in EGR piping.

  An EGR control device according to the present invention for solving such a problem is based on an EGR cooler into which a cooling water path is drawn, an alcohol concentration detection means for detecting an alcohol concentration in fuel, and a detection result by the alcohol concentration detection means. Cooling water amount control means for controlling the amount of cooling water flowing through the cooling water path. By adopting such a configuration, when the alcohol concentration is high, the cooling performance of the EGR cooler can be reduced to avoid excessive cooling of the EGR gas, and moisture condensation can be suppressed. As a result, it is possible to maintain the function of the EGR device.

  Such an EGR control device can be configured to include an EGR rate control means for controlling the EGR rate based on the detection result of the alcohol concentration detection means. The higher the concentration of the alcohol fuel, the more the amount of water generated in the EGR gas. Therefore, when the alcohol concentration is high, the EGR rate is controlled to reduce the amount of EGR gas introduced. By reducing the amount of EGR gas containing moisture, generation of condensed water can be suppressed. At the same time, the amount of cooling water flowing through the cooling water path is reduced. When the amount of EGR gas is reduced, if the cooling performance of the EGR cooler is constant, cooling of the EGR gas is promoted, and there is a risk of promoting the generation of condensed water. Then, the production | generation of condensed water can be suppressed by reducing the cooling water quantity which distribute | circulates a cooling water path | route, and reducing the cooling performance of an EGR cooler.

  Further, such an EGR control device includes a moisture detection unit that detects moisture contained in the fuel, and the cooling water amount control unit uses the amount of cooling water flowing through the cooling water path based on a detection result by the moisture detection unit. It can be set as the structure which controls. As fuel used for the engine, water is not generated by a combustion reaction, but so-called poor fuel in which water is mixed from the beginning may be used. In this way, moisture mixed into the fuel can also cause clogging in the EGR pipe. Therefore, when the moisture mixed in the fuel is detected and the moisture content is high, the cooling performance of the EGR cooler can be lowered and the generation of condensed water in the EGR pipe can be suppressed. Even when such poor fuel is used, the EGR rate can be controlled to reduce the amount of EGR gas introduced. By reducing the amount of EGR gas containing moisture, the amount of condensed water generated can be suppressed. At the same time, the amount of cooling water flowing through the cooling water path is reduced. When the amount of EGR gas is reduced, if the cooling performance of the EGR cooler is constant, cooling of the EGR gas is promoted, and there is a risk of promoting the generation of condensed water. Then, the production | generation of condensed water can be suppressed by reducing the cooling water quantity which distribute | circulates a cooling water path | route, and reducing the cooling performance of an EGR cooler.

  The moisture detection means in such an EGR control device can detect moisture based on a difference in combustion speed according to a moisture content ratio in the fuel.

  According to the present invention, since the cooling performance of the EGR cooler is controlled based on the alcohol concentration in the fuel, clogging caused by condensed water in the EGR pipe can be suppressed.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a spark ignition type multi-cylinder (4-cylinder) engine 10 provided with an EGR control device according to a first embodiment of the present invention. The engine 10 includes a cylinder block portion 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like, a cylinder head portion 30 fixed to the upper side of the shilling block portion 20, and a fuel mixture to the cylinder block portion 20. An intake system 40 for supplying and an exhaust system 50 for releasing exhaust gas from the cylinder block unit 20 to the outside are included. Further, an EGR device 80 is mounted between the exhaust system 50 and the intake system 40.

  The engine 10 can use only gasoline (ethanol concentration Re = 0%), gasoline containing ethanol, and only ethanol (ethanol concentration Re = 100%) as fuel. Here, the ethanol concentration Re is a percent concentration defined by “Ve / (Vg + Ve)”, where Vg is the volume of gasoline contained in the fuel and Ve is the volume of ethanol contained in the fuel.

  The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23. As a result, the crankshaft 24 rotates. The head portions of the cylinder 21 and the piston 22 form a combustion chamber 25 together with the cylinder head portion 30. A water jacket 21 a is formed on the cylinder block 21.

  The cylinder head portion 30 includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake camshaft that drives the intake valve 32, and a phase angle of the intake camshaft is continuously set. A variable intake timing device 33 to be changed and an actuator 33a of the variable intake timing device 33 are provided. Also, an exhaust port 34 communicating with the combustion chamber 25, an exhaust valve 35 that opens and closes the exhaust port 34, an exhaust camshaft 36 that drives the exhaust valve 35, an ignition plug 37, and an ignition coil that generates a high voltage applied to the ignition plug 37 And a fuel injection valve 39 for injecting fuel into the intake port 31.

  The intake system 40 communicates with the intake port 31 and includes an intake pipe 41 including an intake manifold that forms an intake passage together with the intake port 31, an air filter 42 provided at an end of the intake pipe 41, and the intake pipe 41. The throttle valve 43 has a variable opening cross-sectional area of the intake passage, and a throttle valve actuator 43a composed of a DC motor constituting throttle valve driving means.

  The exhaust system 50 includes an exhaust manifold 51 communicating with the exhaust port 34, an exhaust pipe 52 connected to the exhaust manifold 51, and a three-way catalyst 53 disposed on the exhaust pipe 52. The exhaust port 34, the exhaust manifold 51, and the exhaust pipe 52 constitute an exhaust passage.

  The EGR device 80 includes an EGR pipe 81 that connects between the exhaust manifold 51 and the intake manifold 41, and an EGR valve 82 that is disposed in the EGR pipe 81. A step motor is incorporated in the EGR valve 82. By controlling the step motor, the opening degree of the EGR valve 82 is adjusted, and the EGR rate is changed. The EGR pipe 81 is provided with an EGR cooler 83, and a cooling water pipe 84 connected to the water jacket 21a is drawn into the EGR cooler 83. The cooling water pipe 84 forms a cooling water path in the present invention. The cooling water pipe 84 is equipped with an EGR cooling water amount control valve 85 that functions as the cooling water amount control means in the present invention in cooperation with the ECU 70.

  The engine 10 includes an air flow meter 61, a throttle position sensor 62, a cam position sensor 63, a crank position sensor 64, a water temperature sensor 65, an air-fuel ratio sensor 66, and a combustion chamber pressure sensor 67.

  The air flow meter 61 detects the mass flow rate of the intake air flowing through the intake pipe 41 per unit time, and outputs a signal representing the mass flow rate (intake air flow rate) Ga. The throttle position sensor 62 detects the degree of engagement of the throttle valve 43 and outputs a signal representing the degree of throttle valve relation. The cam position sensor 63 generates a signal (G2 signal) having one pulse every time the intake camshaft rotates 90 °. This signal represents the opening / closing timing of the intake valve 32.

  The crank position sensor 64 outputs a signal having a narrow pulse every time the crankshaft 24 rotates 10 ° and a wide pulse every time the crankshaft 24 rotates 360 °. This signal represents the operating speed NE. The water temperature sensor 65 detects the temperature of the cooling water of the engine 10 and outputs a signal representing the cooling water temperature THW.

  The air-fuel ratio sensor 66 is disposed upstream of the three-way catalyst 53 on the exhaust passage. The air / fuel ratio sensor 66 detects the air / fuel ratio of the exhaust gas flowing into the three-way catalyst 53 and outputs a voltage corresponding to the air / fuel ratio of the exhaust gas.

  The combustion chamber pressure sensor 67 detects the gas pressure in the combustion chamber 25 and outputs a signal representing the gas pressure.

  An ECU (Electronic control unit) 70 cooperates with various sensors, valves, and other components included in the engine 10 to provide alcohol concentration detection means, moisture detection means, cooling water amount control means, and EGR rate control in the present invention. The CPU 71 is connected to each other by a path, a routine (program) executed by the CPU 71, a table (map), a ROM 72 in which constants are stored in advance, and the CPU 71 stores data as necessary. A microcomputer comprising a RAM 73 for temporarily storing data, a backup RAM 74 for storing data while the power is turned on and retaining the stored data even while the power is shut off, an interface 75 including an AD converter, and the like It is.

  The interface 75 is connected to the sensors 61 to 67, supplies signals from the sensors 61 to 67 to the CPU 71, and in response to an instruction from the CPU 71, the actuator 33a, the igniter 38, and the fuel injection valve 39 of the variable intake timing device 33. And drive signals to the throttle valve actuator 43a, the EGR valve 82, the EGR cooling water amount control valve 85, and the like.

  Next, an outline of control performed by the ECU 70 in the engine 10 configured as described above will be described. The ECU 70 basically determines the fuel injection amount based on the output value of the air-fuel ratio sensor 66 so that the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio. Moreover, the amount of cooling water introduced into the EGR cooler through the cooling water pipe 84 is controlled. Furthermore, the EGR rate is controlled with the aim of reducing the fuel consumption rate by reducing pump loss, cooling loss, and specific heat ratio.

Specific control performed by the ECU 70 will be described with reference to the flowchart shown in FIG. First, in step S1, the properties of the fuel are acquired. Here, the properties of the fuel include the properties of the fuel such as whether or not ethanol (alcohol) is contained in the fuel and the concentration of the contained ethanol. The ethanol concentration (Ret) is calculated according to the following policy.
If the theoretical air-fuel ratio (known) of gasoline is AFg, the theoretical air-fuel ratio (known) of ethanol is AFe, the fuel injection amount is Gf, and the air amount is Ga, the ethanol concentration Re is

Ga = AFg * (1-Re / 100) * Gf + AFe * Re / 100 * Gf
Therefore,
Re = 100 (Ga / Gf-AFg) / (AFe-AFg)
It becomes.

  In addition, it can also be set as the structure which attaches an alcohol concentration sensor to fuel piping, and grasps | ascertains alcohol concentration. As the alcohol concentration sensor, for example, a capacitive sensor that detects the alcohol concentration in the fuel based on a change in dielectric constant or the like can be used.

  The ECU 70 proceeds to step S2 after acquiring the fuel properties as described above in step S1. In step S2, it is determined whether or not ethanol is mixed in the fuel from the fuel property acquired in step S1. When it is determined No in this determination, that is, when mixing of ethanol is not recognized in the fuel, the process returns. On the other hand, when mixing of ethanol in the fuel is recognized, the process proceeds to step S3.

  In step S3, a map reference for controlling the amount of cooling water introduced into the EGR cooler 83 is performed. First, the EGR cooler introduction cooling water amount determination map shown in FIG. 3 is referred to. This is a map for determining the amount of cooling water to be introduced into the EGR cooler 83 through the cooling water pipe 84 in accordance with the ethanol concentration acquired in step S1. The amount of cooling water introduced into the EGR cooler becomes smaller as the ethanol concentration is higher. In other words, the higher the ethanol concentration, the more water components in the EGR gas, so the cooling of the EGR gas in the EGR cooler 83 is suppressed, thereby suppressing the generation of condensed water.

  Subsequently, the ECU 70 determines the throttle amount of the EGR cooling water amount control valve 85 for realizing the EGR cooler introduction cooling water amount determined based on the EGR cooler introduction cooling water amount determination map shown in FIG. Specifically, the EGR cooling water amount control valve throttle amount determination map shown in FIG. 4 is referred to. The ECU 70 decreases the throttle amount of the EGR cooling water amount control valve 85 when the amount of cooling water to be introduced is large, and increases the throttle amount of the EGR cooling water amount control valve 85 when the amount of cooling water to be introduced is small.

  After the throttle amount of the EGR cooling water amount control valve 85 is determined in step S3, the process proceeds to step S4, and a command is issued to the EGR cooling water amount control valve 85 so as to be the throttle amount determined in step S3.

  By performing the control as described above, it is possible to cool the EGR gas according to the ethanol concentration in the fuel, and to suppress the generation of condensed water. Thereby, clogging of the EGR pipe 84 can be suppressed.

  When it is determined No in step S2, the EGR cooling water amount control valve 85 is fully opened.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. Since the configuration of the engine 10 itself provided with the EGR control device is the same as that of the first embodiment, detailed description thereof is omitted. The second embodiment differs from the first embodiment in that the first embodiment only controls the amount of cooling water introduced into the EGR cooler 83 in accordance with the ethanol concentration in the fuel. In the second embodiment, The EGR rate is also controlled according to the ethanol concentration. Hereinafter, specific control will be described with reference to the flowchart shown in FIG.

  First, in step S11, the property of the fuel is acquired, and subsequently, in step S12, it is determined whether or not ethanol is mixed in the fuel. Since the processes in steps S11 and S12 are the same as the processes in steps S1 and S12 in the first embodiment, detailed description thereof is omitted.

  ECU70 which finished the process of step S12 refers to the EGR rate and EGR cooler introduction cooling water amount determination map shown in FIG. 6 in step S13. The EGR rate decreases as the ethanol concentration increases. That is, the higher the ethanol concentration, the lower the amount of EGR gas introduced. As described above, the amount of cooling water introduced into the EGR cooler is also reduced as the amount of EGR gas introduced is reduced. Decreasing the amount of EGR gas introduced and lowering the EGR rate will reduce the water component itself that is the source of condensed water. Thus, if the amount of cooling water is constant when the amount of EGR gas introduced is reduced, the cooling capacity of the EGR cooler 83 with respect to the amount of EGR gas becomes excessive, and condensed water generation is promoted. Therefore, the amount of cooling water introduced is reduced as the EGR rate decreases.

  In step S13, the EGR cooling water amount control valve throttle amount determination map shown in FIG. 4 is referred to in order to determine the throttle amount of the EGR cooling water amount control valve 85 for realizing the determined EGR cooler introduction cooling water amount. This is the same as in the case of the first embodiment. That is, the ECU 70 decreases the throttle amount of the EGR cooling water amount control valve 85 when the amount of cooling water to be introduced is large, and increases the throttle amount of the EGR cooling water amount control valve 85 when the amount of cooling water to be introduced is small.

  After the EGR rate and the throttle amount of the EGR cooling water amount control valve 85 are determined in step S13, a command is issued to the EGR valve 82 in step S14 to change the EGR rate, and a command is issued to the EGR cooling water amount control valve 85 in step S15. To emit. In addition, the process of step S14 and the process of step S15 may be replaced, and may be performed simultaneously.

  By performing the control as described above, it is possible to cool the EGR gas according to the ethanol concentration in the fuel, and to suppress the generation of condensed water. Thereby, clogging of the EGR pipe 84 can be suppressed.

  Next, Embodiment 3 of the present invention will be described with reference to the drawings. Since the configuration of the engine 10 itself provided with the EGR control device is the same as that of the first embodiment, detailed description thereof is omitted. The third embodiment is different from the first embodiment in that the third embodiment takes measures when a so-called poor fuel in which moisture is mixed into the fuel from the beginning is used. Hereinafter, specific control will be described with reference to the flowchart shown in FIG.

  First, in step S21, the property of the fuel is acquired. Here, the properties of the fuel, such as whether or not ethanol is contained in the fuel and the concentration of the contained ethanol, are included in the fuel properties as in the first embodiment. It is. In Example 3, in addition to these, the amount of water contained in the fuel is also a target. Moisture detection is performed by paying attention to the difference in combustion speed according to the moisture content in the fuel.

  Hereinafter, detection of the water content in the fuel will be described. In detecting the moisture content, the pressure change in the combustion chamber acquired by the combustion chamber pressure sensor 67 is referred to. The detection of the moisture content will be described. FIG. 8 is a graph showing the relationship between the crank angle and the gas pressure in the combustion chamber when ignition is performed at the ignition timing CAig. Moisture mixed in the fuel does not contribute to the combustion reaction in the combustion chamber. It also takes away some of the combustion heat of combustible components. For this reason, if the air-fuel ratio is constant, the temperature of the gas in the combustion chamber decreases as the water content (ratio) increases. As a result, the higher the moisture content, the slower the mixture burns.

  The ECU 70 stores in advance reference curve data indicating a pressure change in the combustion chamber when the water content is zero. This reference curve data is indicated by a solid line in FIG. In the reference curve data, the crank angle at which the gas pressure in the combustion chamber reaches the maximum value is the value CAl. The output torque at this time becomes the maximum value at the value TQl. On the other hand, when water is mixed in the fuel, the crank angle at which the maximum pressure appears when the ignition is performed at the same timing as the ignition timing CAig in the reference curve data becomes the value CA2 on the retard side of the value CA1. The degree of shift of the value CA2 from the value CA1 to the retard side increases as the combustion speed of the air-fuel mixture decreases. Since the combustion rate becomes slower as the water content increases, the degree of shift of the value CA2 from the value CA1 to the retard side becomes larger. The ECU 70 estimates the moisture content in the fuel based on the shift amount of the value CA2 from the value CA1 to the retard side, and outputs it as a detected value.

  Note that when water is mixed in the fuel, for example, the torque value observed at the crank angle CA1 falls compared to the reference curve data. The moisture content in the fuel can also be estimated from the torque drop amount.

  In step S22, the ECU 70 that has acquired the fuel property in step S21 determines whether or not ethanol has been mixed into the fuel based on the fuel property acquired in step S21. When it is determined No in this determination, that is, when mixing of ethanol is not recognized in the fuel, the process returns. On the other hand, when mixing of ethanol in the fuel is recognized, the process proceeds to step S23.

  In step S23, a map reference for controlling the amount of cooling water introduced into the EGR cooler 83 is performed. First, the EGR cooler introduction cooling water amount determination map shown in FIG. 9 is referred to. However, at this stage, the map indicated by the line segment A to be the reference map is selected.

  Subsequently to this, the ECU 70 performs the process of step S24. In step S24, it is determined whether or not moisture has been mixed into the fuel from the fuel properties acquired in step S21. When it is determined No in step S24, that is, when moisture is not detected from the fuel, the process of step S26 is performed without performing the process of step S25.

  On the other hand, when it is determined Yes in step S24, that is, when moisture is detected from the fuel, the process proceeds to step S25. In step S25, the amount of cooling water introduced into the EGR cooler is corrected. Specifically, the map indicated by the line segment A selected in step S23 is shifted to the map indicated by the line segment B. Thus, when moisture is detected from the fuel, measures are taken to further reduce the amount of introduced cooling water. That is, when moisture is detected from the fuel, the cooling performance of the EGR cooler 83 is further reduced, and the generation of condensed water is suppressed. Note that as the water content increases, the amount of cooling water introduced is reduced accordingly. That is, when the water content increases, the map selected in accordance with the water content shifts downward from the map represented by the line A when the fuel does not contain water.

  In step S26, the ECU 70 determines the throttle amount of the EGR cooling water amount control valve 85 for realizing the EGR cooler introduction cooling water amount determined in step S23 or step S25, and the EGR cooling water amount control valve throttle shown in FIG. Refer to the quantity determination map. This is the same as in the first embodiment. That is, the ECU 70 decreases the throttle amount of the EGR cooling water amount control valve 85 when the amount of cooling water to be introduced is large, and increases the throttle amount of the EGR cooling water amount control valve 85 when the amount of cooling water to be introduced is small.

  After the throttle amount of the EGR cooling water amount control valve 85 is determined in step S26, the process proceeds to step S27, and a command is issued to the EGR cooling water amount control valve 85 so that the throttle amount determined in step S26 is obtained.

  By performing the control as described above, it is possible to cool the EGR gas according to the ethanol concentration in the fuel, and to suppress the generation of condensed water. Thereby, clogging of the EGR pipe 84 can be suppressed.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, the engine 10 can be configured as shown in FIG. 10 as a measure when the moisture contained in the so-called bad fuel exceeds the limit amount. That is, the switching valve 86 is attached to the EGR pipe 84 upstream of the EGR cooler 83 and the moisture trap path 87 of the EGR pipe 84 is connected. A moisture trap 87 that captures moisture in the EGR gas is installed in the moisture trap path 87. The moisture trap 87 may be pot-shaped or filter-shaped. Thus, by removing moisture from the EGR gas in advance, it is possible to suppress the generation of condensed water when the EGR gas is cooled by the EGR cooler 83. FIG. 11 is a flowchart illustrating an example of control of the switching valve 86. First, in step S31, the fuel property is acquired and the water content in the fuel is grasped. In step S32, it is determined whether or not the moisture content exceeds a predetermined limit value. When it is determined Yes in step S32, the switching valve 86 is switched in step S33, and the moisture trap path 87 is selected. Condensed water production can be suppressed through such treatment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a schematic configuration of a spark ignition type multi-cylinder (4-cylinder) engine provided with an EGR control device according to a first embodiment; It is a flowchart which shows an example of control of the amount of EGR cooler introduction cooling water. It is a figure which shows an example of an EGR cooler introduction cooling water amount determination map. It is a figure which shows an example of an EGR cooling water amount control valve throttle amount determination map. It is a flowchart which shows an example of control of an EGR rate and an EGR cooler introduction | transduction cooling water amount. It is a figure which shows an example of an EGR rate and an EGR cooler introduction cooling water amount determination map. It is a flowchart which shows an example of control in case the water | moisture content is mixed in the fuel. It is the graph which showed the relationship between the crank angle and the pressure of the gas in a combustion chamber when ignition is performed at the ignition timing CAig. It is a figure which shows an example of the EGR cooler introduction cooling water amount determination map in case there exists correction | amendment of EGR cooler introduction cooling water amount. It is explanatory drawing which showed schematic structure of the engine of another Example. It is a flowchart which shows an example of the control which selects a moisture trap path | route.

Explanation of symbols

10 Engine 40 Intake system 50 Exhaust system 67 In-cylinder pressure sensor 70 ECU
80 EGR device 82 EGR valve 83 EGR cooler 84 Cooling water pipe 85 EGR cooling water amount control valve

Claims (4)

An EGR cooler into which the cooling water path is drawn,
Alcohol concentration detection means for detecting the alcohol concentration in the fuel;
Cooling water amount control means for controlling the amount of cooling water flowing through the cooling water path based on the detection result by the alcohol concentration detection means;
An EGR control device comprising: The EGR control device according to claim 1,
An EGR control device comprising an EGR rate control means for controlling an EGR rate based on a detection result by the alcohol concentration detection means. The EGR control device according to claim 1,
EGR control characterized by comprising water detection means for detecting water contained in the fuel, wherein the cooling water amount control means controls the amount of cooling water flowing through the cooling water path based on a detection result by the water detection means. apparatus. The EGR control device according to claim 3,
The EGR control device characterized in that the moisture detection means detects moisture based on a difference in combustion speed according to a moisture content ratio in the fuel.

Images