JP2011236816A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine that prevents progress of dry corrosion.SOLUTION: The device includes a fuel supply passage 12 which supplies an alcohol containing fuel to the internal combustion engine 10 and at least part of which is aluminum made. The device also determines whether the dry corrosion occurs, and adds water to the fuel supply passage 12 when determining that dry corrosion occurs.

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus suitable for executing control of an internal combustion engine mounted on a vehicle.

  Conventionally, as disclosed in Patent Document 1, for example, an internal combustion engine having an aluminum fuel pipe through which an alcohol-containing fuel flows is known. In such an internal combustion engine, dry corrosion in which aluminum is corroded by an alcohol-containing fuel can occur. Dry corrosion particularly proceeds rapidly under an environment of high temperature and low moisture concentration. Patent Document 1 discloses that the temperature of the fuel pipe is lowered under conditions where dry corrosion occurs. By reducing the temperature of the fuel pipe, dry corrosion is suppressed.

JP 2009-40255 A JP 2006-257907 A JP 2007-198198 A

  However, once dry corrosion occurs, water is used for the reaction, and the water concentration further decreases. If the water concentration decreases, the occurrence of dry corrosion is promoted. Therefore, as in Patent Document 1 described above, the progress of dry corrosion cannot be sufficiently suppressed only by reducing the temperature of the fuel pipe.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can suppress the progress of dry corrosion.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
A path for supplying alcohol-containing fuel to the internal combustion engine, at least a portion of which is made of aluminum; and
Dry corrosion determination means for determining whether or not dry corrosion occurs;
And a water adding means for adding water to the fuel supply path when dry corrosion occurs.

A second invention is an internal combustion engine control apparatus for achieving the above object,
A path for supplying alcohol-containing fuel to the internal combustion engine, at least a portion of which is made of aluminum; and
Moisture concentration acquisition means for acquiring the moisture concentration of the alcohol-containing fuel;
Moisture concentration determination means for determining whether the moisture concentration acquired by the moisture concentration acquisition means is equal to or less than a specified value;
Water addition means for adding water to the fuel supply path when the water concentration acquired by the water concentration acquisition means is equal to or less than the specified value.

A third aspect of the invention is a control device for an internal combustion engine in order to achieve the above object,
A path for supplying alcohol-containing fuel to the internal combustion engine, at least a portion of which is made of aluminum; and
A fluctuation amount obtaining means for obtaining a fluctuation amount of the engine speed at the time of starting the engine;
A fluctuation amount determination means for determining whether or not the fluctuation amount acquired by the fluctuation amount acquisition means is a specified value or more;
Water addition means for adding water to the fuel supply path when the fluctuation amount acquired by the fluctuation amount acquisition means is greater than or equal to the specified value.

  According to the first invention, water can be added to the fuel supply path when dry corrosion occurs. By adding water, the water concentration in the alcohol-containing fuel can be increased. For this reason, according to this invention, generation | occurrence | production and progress of dry corrosion can be suppressed.

  According to the second aspect of the present invention, water can be added to the fuel supply path when the water concentration of the alcohol-containing fuel is not more than the specified value. For this reason, according to the present invention, the water concentration in the alcohol-containing fuel can be maintained high, and the occurrence and progression of dry corrosion can be suppressed.

  According to the third aspect of the present invention, water can be added to the fuel supply path when the fluctuation amount of the engine speed at the time of starting the engine is equal to or greater than a specified value. Therefore, according to the present invention, the moisture concentration in the alcohol-containing fuel can be increased according to the amount of fluctuation in the engine speed at the time of starting the engine, and the progress of dry corrosion can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a timing chart for demonstrating the content of the characteristic operation | movement performed in Embodiment 1 of this invention. It is a flowchart of the control routine which ECU50 performs in Embodiment 1 of this invention. In Embodiment 2 of this invention, it is a figure showing the fluctuation | variation of the engine speed at the time of a start in case the oil tightness defect arises. It is a flowchart of the control routine which ECU50 performs in Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a schematic configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10. The internal combustion engine 10 generally has a plurality of cylinders. The internal combustion engine 10 is connected to a fuel supply path 12 for receiving supply of an alcohol-containing fuel (for example, a mixed fuel of gasoline and ethanol) from a fuel tank (not shown).

  A fuel tank for storing alcohol-containing fuel is connected to the upstream end of the fuel supply path 12. A fuel pipe 13 is connected to the fuel tank. The fuel pipe 13 is provided with a high-pressure fuel pump 14. The high-pressure fuel pump 14 is a pump that pumps the alcohol-containing fuel downstream using the driving force of the cam 16. A delivery pipe 18 is connected to the fuel pipe 13 downstream of the high-pressure fuel pump 14. An injector 20 is attached to the delivery pipe 18 for each cylinder. The injector 20 is an in-cylinder injector that is provided at the downstream end of the fuel supply path 12 and injects alcohol-containing fuel into the combustion chamber. The fuel supply path 12 includes a fuel pipe 13, a high-pressure fuel pump 14, a delivery pipe 18, and an injector 20.

  The system of this embodiment is provided with a steam condensation tank 22. The input side of the steam condensation tank 22 is connected to the exhaust passage 24, and the output side is connected to the fuel pipe 13 in the vicinity of the high-pressure fuel pump 14. The water vapor condensing tank 22 introduces a part of the exhaust gas from the exhaust passage 24, condenses the water vapor in the exhaust gas by heat radiation in the introduction path and cooling with engine cooling water, and collects it as moisture. It is a tank. Between the steam condensing tank 22 and the fuel pipe 13, a water addition valve 26 that is controlled to be opened and closed by an ECU 50 described later is provided. When the water addition valve 26 is opened, the water collected in the tank is introduced into the fuel pipe 13.

  Further, in the system of the present embodiment, at least a part of the fuel supply path 12 located downstream of the water addition valve 26 is formed of an aluminum member. In the system of this embodiment, as an example, it is assumed that the delivery pipe 18 is made of aluminum.

  The delivery pipe 18 is provided with a temperature sensor 28 for detecting the temperature of the alcohol-containing fuel and a moisture amount sensor 30 for detecting the moisture content of the alcohol-containing fuel.

  The system of this embodiment includes an ECU (Electronic Control Unit) 50. In the input part of the ECU 50, there are various sensors such as the temperature sensor 28, the moisture sensor 30, the crank angle sensor 52 for detecting the crank angle, and the alcohol concentration sensor 54 for detecting the alcohol concentration in the fuel. It is connected. Various actuators such as the injector 20 and the water addition valve 26 are connected to the output section of the ECU 50. The ECU 50 controls the operating state of the internal combustion engine 10 by operating various actuators according to a predetermined program based on the outputs of the various sensors.

[Characteristic Control in Embodiment 1]
In the system configuration described above, dry corrosion in which aluminum is corroded by the alcohol-containing fuel may occur. Dry corrosion particularly proceeds rapidly under an environment of high temperature and low moisture concentration. Here, since the delivery pipe 18 is for direct injection and is close to the engine body, it has a high pressure and a high temperature. When dry corrosion occurs, water is used for the reaction, so that the water concentration is further reduced. If the moisture concentration decreases, the occurrence of dry corrosion is promoted. Therefore, in the system according to the present embodiment, the occurrence and progression of dry corrosion is suppressed by performing control that suitably suppresses the decrease in moisture concentration.

  A more specific outline of the control will be described with reference to FIG. FIG. 2 is a timing chart for explaining the contents of characteristic operations executed in the second embodiment of the present invention. In the timing chart shown in FIG. 2, at time t1, the water content (solid line 62) of the alcohol-containing fuel in the delivery pipe 18 is lower than the saturated water content (broken line 60) (FIG. 2 (C)). In this case, the water addition valve 26 is opened (FIG. 2A). By opening the water addition valve, the amount of water rises and reaches the saturated amount of water at time t2 (FIG. 2C). When the saturated water content is reached, the water addition valve 26 is closed (FIG. 2A).

  As shown in FIG. 2 (B), since the temperature of the alcohol-containing fuel in the delivery pipe 18 continues to rise, the saturated water content (broken line 60) also rises (FIG. 2 (C)). As a result, the water content of the alcohol-containing fuel is again lower than the saturated water content (FIG. 2C). Therefore, the water addition valve 26 is opened again at time t3 (FIG. 2A). Thus, in the system of this embodiment, control is performed so that the water content of the alcohol-containing fuel is kept at the saturated water content.

(Control routine)
Next, a control routine for realizing the above-described operation will be described. FIG. 3 is a flowchart of a control routine executed by ECU 50 in the first embodiment of the present invention. This control routine is executed every predetermined time. In the routine shown in FIG. 3, first, the moisture amount sensor 30 detects the moisture amount (moisture concentration) W per unit fuel amount in the delivery pipe 18 (step 100).

  Next, the fuel temperature T in the delivery pipe 18 is detected by the temperature sensor 28 (step 110). Subsequently, the saturated water content Wsa corresponding to the fuel temperature T is calculated (step 120). The ECU 50 stores in advance a map in which the saturated water content Wsa is set higher as the fuel temperature T is higher.

  Then, it is determined whether or not the water content W is smaller than the saturated water content Wsa (step 130). If it is determined that the water content W is less than the saturated water content Wsa, the water addition valve 26 is opened (step 140). On the other hand, when it is determined that the water content W has reached the saturated water content Wsa, the water addition valve 26 is closed. Thereafter, the processing of this routine is terminated.

  As described above, according to the routine shown in FIG. 3, the water addition valve 26 is opened when the water content W of the alcohol-containing fuel is smaller than the saturated water content Wsa. By opening the water addition valve 26, the moisture concentration of the alcohol-containing fuel can be increased. In addition, according to this routine, the water addition valve 26 is closed when the water content W of the alcohol-containing fuel reaches the saturated water content Wsa. From these, the water content W of the alcohol-containing fuel can be matched with the saturated water content Wsa. As described above, when dry corrosion occurs, water is used in the reaction to reduce the water concentration and promote the occurrence of dry corrosion. According to the system of this embodiment, the moisture in the fuel is reduced. It is possible to suppress the occurrence and progression of dry corrosion by controlling the amount of saturated moisture.

  Further, as described above, dry corrosion is likely to occur at high temperature and low moisture concentration. However, according to the routine shown in FIG. 3, the higher the fuel temperature T, the higher the saturated moisture amount Wsa and the higher the moisture amount Wsa. Can be increased. Therefore, according to the system of the present embodiment, it is possible to suitably suppress the occurrence / progress of dry corrosion even at high temperatures.

  By the way, in the system of Embodiment 1 mentioned above, the target value of the water content W is set to the saturated water content Wsa, but this target value is not limited to this. For example, it may be a specified amount of water determined according to operating conditions. This point is the same in the following embodiments.

  In the system of the first embodiment described above, the in-cylinder injector 20 and the delivery pipe 18 are used downstream of the fuel supply path 12, but the configuration is not limited to this. . For example, a port injection injector and a delivery pipe that inject alcohol-containing fuel into the intake port may be used. This point is the same in the following embodiments.

  In the first embodiment described above, the fuel supply path 12 is the “fuel supply path” in the first and second inventions, and the moisture amount sensor 30 is the “moisture concentration acquisition means” in the second invention. , Respectively. In addition, here, the ECU 50 executes the process of step 130, so that the “dry corrosion determining means” in the first invention executes the process of step 130, and the “moisture content” in the second invention is executed. The “concentration determination means” implements the “water addition means” in the first and second inventions by executing the processing of step 140 described above.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 5 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 2]
When dry corrosion occurs, the dissolved aluminum becomes a solid foreign substance and flows into the injector. If foreign matter flows into the injector, for example, the foreign matter may be caught in the seat portion, the fuel seal may be incomplete, and oil tightness may occur. FIG. 4 is a diagram showing fluctuations in engine speed at start-up when an oil tightness defect occurs. If an oil tightness defect occurs, fuel will ooze out when the engine is stopped and flow into the engine cylinder. As a result, combustion fluctuation and HC increase are caused at the next start. Due to such abnormal combustion, a rotational fluctuation exceeding a specified value as shown in FIG. 4 occurs.

  Therefore, in the system of the present embodiment, when the fluctuation amount of the engine speed after the start is larger than the specified value, it is determined that an oil tightness defect due to dry corrosion has occurred, and water is added, and dry corrosion It was decided to suppress the occurrence and progression.

(Control routine)
Next, a control routine for realizing the above-described operation will be described. FIG. 5 is a flowchart of a control routine executed by ECU 50 in the first embodiment of the present invention. This control routine is repeatedly executed for a certain period after the engine is started. In the routine shown in FIG. 5, it is first determined whether or not the ethanol concentration E detected by the alcohol concentration sensor 54 is within a predetermined range (step 200). As the predetermined range, a range where the risk of occurrence of dry corrosion is high is set. For example, an ethanol concentration of about 85% is set. When it is determined that the ethanol concentration E is outside the predetermined range, normal operation is performed (step 210).

  On the other hand, when it is determined that the ethanol concentration E is within the predetermined range, it is determined whether or not the fluctuation amount of the engine speed NE is greater than or equal to a specified value (step 220). When the fluctuation amount of the engine speed NE is less than the specified value, normal operation is performed (step 210). The engine speed NE is calculated based on the output signal of the crank angle sensor 52, and the fluctuation amount is calculated from, for example, the difference from the speed in the previous cycle. As the specified value, a value determined by experiment or the like that can determine that abnormal combustion due to fuel seepage has occurred is set.

  On the other hand, when it is determined that the fluctuation amount of the engine speed NE is equal to or greater than the specified value, it is determined that the aluminum melted by the dry corrosion is caught in the injector 20 as a foreign matter, resulting in an oil tightness defect. (Step 230). In this case, the water addition valve 26 is opened, and water is added into the fuel supply path 12 (step 240).

  Subsequently, 1 is added to the oil tightness failure counter C (step 250), and it is determined whether or not the oil tightness failure counter C is equal to or less than a specified value (step 260). When the oil tightness defect counter C is equal to or less than the specified value, the process of this routine is ended. On the other hand, when the oil tightness defect counter C is larger than the specified value, a warning light provided in the driver's seat or the like is turned on (step 270). Thereafter, the processing of this routine is terminated.

  As described above, according to the routine shown in FIG. 5, when the ethanol concentration E is in a range where the risk of dry corrosion occurrence is high and the fluctuation amount of the engine speed NE at the time of starting the engine is equal to or greater than a specified value. Then, it is determined that an oil tightness defect due to dry corrosion has occurred, and the water addition valve 26 is opened. By opening the water addition valve 26, the moisture concentration of the alcohol-containing fuel can be increased. As a result, it is possible to suppress the progress of dry corrosion and to suppress the deterioration of oil tightness.

  Further, according to the routine shown in FIG. 5, when the oil tightness counter C exceeds a specified value, the warning lamp can be turned on. The oil tightness failure may be resolved by removing foreign matter while the injector is being driven. If it is determined that the oil tightness failure will not be resolved by providing a counter, an alarm lamp will be turned on and an abnormality will occur. Can be notified to the driver.

  In the second embodiment described above, the fuel supply path 12 corresponds to the “fuel supply path” in the first and third inventions. In addition, here, the ECU 50 executes the process of step 220, so that the “dry corrosion determining means” in the first invention executes the process of step 220, and the “variation” in the third invention is executed. The “amount acquisition means” and the “variation amount determination means” implement the “water addition means” in the first and third inventions by executing the processing of step 240 described above.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Fuel supply path 13 Fuel piping 14 High-pressure fuel pump 18 Delivery pipe 20 Injector 22 Water vapor condensing tank 24 Exhaust passage 26 Water addition valve 28 Temperature sensor 30 Water content sensor 50 ECU (Electronic Control Unit)
52 Crank angle sensor 54 Alcohol concentration sensor

Claims (3)

A path for supplying alcohol-containing fuel to the internal combustion engine, at least a portion of which is made of aluminum; and
Dry corrosion determination means for determining whether or not dry corrosion occurs;
A control device for an internal combustion engine, comprising: water addition means for adding water to the fuel supply path when dry corrosion occurs. A path for supplying alcohol-containing fuel to the internal combustion engine, at least a portion of which is made of aluminum; and
Moisture concentration acquisition means for acquiring the moisture concentration of the alcohol-containing fuel;
Moisture concentration determination means for determining whether the moisture concentration acquired by the moisture concentration acquisition means is equal to or less than a specified value;
Water addition means for adding water to the fuel supply path when the water concentration acquired by the water concentration acquisition means is not more than the specified value;
A control device for an internal combustion engine, comprising: A path for supplying alcohol-containing fuel to the internal combustion engine, at least a portion of which is made of aluminum; and
A fluctuation amount obtaining means for obtaining a fluctuation amount of the engine speed at the time of starting the engine;
A fluctuation amount determination means for determining whether or not the fluctuation amount acquired by the fluctuation amount acquisition means is a specified value or more;
Water addition means for adding water to the fuel supply path when the fluctuation amount acquired by the fluctuation amount acquisition means is greater than or equal to the specified value;
A control device for an internal combustion engine, comprising:

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