JP2009167887A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of properly controlling an EGR valve opening degree based on piston temperature in warming-up of the internal combustion engine. <P>SOLUTION: The control device of the internal combustion engine is suitably used for performing EGR control of the internal combustion engine. Specifically, an EGR valve opening degree calculation means calculates the EGR valve opening degree to be set for an EGR valve based on an operation state of the internal combustion engine and the like, and an EGR valve opening degree correction means corrects the EGR valve opening degree based on the piston temperature in warming-up of the internal combustion engine. Specifically, the correction to the EGR valve opening degree is performed based on a deviation between a piston temperature measurement value measured by a sensor and a piston temperature calculation value calculated based on the operation state. With this, in the warming-up process, the EGR valve can be optimally controlled. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technical field for performing EGR control of an internal combustion engine.

  This type of technique is described in Patent Document 1, for example. Patent Document 1 describes a technique for correcting an EGR rate based on a piston surface temperature (piston temperature) during warm-up of an internal combustion engine. The reason why correction is performed based on the piston surface temperature in this manner is that the piston surface temperature is the temperature that most affects the combustion, so that the correction accuracy of the EGR rate can be maximized by using this. Because it can.

JP 2006-299816 A

  However, in the technique described in Patent Document 1 described above, correction is performed based only on the piston surface temperature obtained by calculation (estimation), and the actual piston surface temperature (piston surface temperature obtained by measurement) is calculated. Did not consider. For this reason, there is a possibility that the EGR rate cannot be appropriately controlled when there is a large deviation between the piston surface temperature obtained by calculation and the actual piston surface temperature.

  The present invention has been made to solve the above-described problems, and controls an internal combustion engine capable of appropriately controlling the EGR valve opening based on the piston temperature when the internal combustion engine is warmed up. An object is to provide an apparatus.

  In one aspect of the present invention, an internal combustion engine control device that controls an EGR valve provided on an EGR passage that recirculates exhaust gas from the internal combustion engine is based on at least the operating state of the internal combustion engine. Calculated by the EGR valve opening calculating means for calculating the EGR valve opening to be set for the valve, and the EGR valve opening calculating means based on the piston temperature in the internal combustion engine when the internal combustion engine is warmed up. EGR valve opening correction means for correcting the EGR valve opening.

  The control device for an internal combustion engine is preferably used for performing EGR control of the internal combustion engine. Specifically, the EGR valve opening calculation means calculates the EGR valve opening to be set for the EGR valve based on the operating state of the internal combustion engine. The EGR valve opening correction means corrects the EGR valve opening calculated by the EGR valve opening calculation means based on the piston temperature in the internal combustion engine when the internal combustion engine is warmed up. As a result, the EGR valve opening can be appropriately set based on the piston temperature that appropriately indicates the temperature around the combustion chamber that is actually involved in combustion. Therefore, according to the control device for an internal combustion engine described above, the EGR valve can be optimally controlled, and the emission deterioration in the warm-up process can be effectively suppressed.

  In one aspect of the control apparatus for an internal combustion engine, piston temperature acquisition means for acquiring a piston temperature measurement value measured by a sensor, and piston temperature calculation means for determining a piston temperature calculation value based on at least the operating state of the internal combustion engine The EGR valve opening correction means corrects the EGR valve opening using a deviation between the piston temperature measurement value and the piston temperature calculation value as the piston temperature.

  In this aspect, the EGR valve opening correction means is based on the deviation between the piston temperature measurement value measured by the sensor and the piston temperature calculation value obtained based on the operating state of the internal combustion engine, etc. Make corrections. Accordingly, the EGR valve opening can be set appropriately in consideration of the relationship between the calculated piston temperature (piston temperature calculation value) and the actual piston temperature (piston temperature measurement value). Therefore, the EGR valve can be further optimally controlled.

  Preferably, in the control device for an internal combustion engine, the piston temperature calculation means uses a rotation speed and a fuel injection amount as an operation state of the internal combustion engine, and at least one of water temperature, oil temperature, and hydraulic pressure. The calculated piston temperature value is used.

  Preferably, the EGR valve opening calculation means uses the rotational speed and the fuel injection amount as the operating state of the internal combustion engine, and uses at least one of a water temperature, an oil temperature, and a hydraulic pressure, The EGR valve opening is calculated.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[overall structure]
FIG. 1 is a schematic diagram showing a configuration of a vehicle 50 to which the control device for an internal combustion engine according to the present embodiment is applied. In FIG. 1, solid arrows indicate gas flows, and broken arrows indicate input / output of signals.

  The vehicle 50 mainly includes an intake passage 3, an engine (internal combustion engine) 4, an exhaust passage 5, an EGR passage 6, an EGR valve 7, a rotation speed sensor 11, a water temperature sensor 12, and an oil temperature sensor 13. And a hydraulic pressure sensor 14, a piston temperature sensor 15, and an ECU (Engine Control Unit) 20.

  Air (intake air) introduced from the outside passes through the intake passage 3, and intake air is supplied to the engine 4 from the intake passage 3. The engine 4 generates power by burning a mixture of fuel and intake air in a combustion chamber (not shown). Exhaust gas generated by the combustion is discharged from the exhaust passage 5.

  An EGR passage 6 is connected on the exhaust passage 5. Specifically, the EGR passage 6 has one end connected to the exhaust passage 5 and the other end connected to the intake passage 3 so that exhaust gas (EGR gas) is recirculated to the intake system. ing. The EGR passage 6 is provided with an EGR valve 7 capable of adjusting the amount of EGR gas to be recirculated to the intake system. The opening degree of the EGR valve 7 is controlled by a control signal supplied from the ECU 20 (hereinafter referred to as “EGR valve opening degree”).

  The rotational speed sensor 11 is configured to be able to detect the rotational speed of the engine 4 (engine rotational speed), and supplies a signal corresponding to the detected engine rotational speed to the ECU 20. The water temperature sensor 12 is configured to be able to detect the temperature (water temperature) of cooling water that cools the engine 4 and the like, and supplies a signal corresponding to the detected water temperature to the ECU 20. The oil temperature sensor 13 is configured to be able to detect the temperature (oil temperature) of the engine oil, and supplies a signal corresponding to the detected oil temperature to the ECU 20. The hydraulic pressure sensor 14 is configured to be able to detect the pressure (hydraulic pressure) of the engine oil, and supplies a signal corresponding to the detected hydraulic pressure to the ECU 20. The piston temperature sensor 15 is configured to be able to detect the temperature of the piston in the engine 4 (corresponding to the piston surface temperature), and supplies a signal corresponding to the detected piston temperature to the ECU 20.

  The ECU 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and controls components (such as the engine 4) in the vehicle 50. In the present embodiment, the ECU 20 controls the EGR valve opening by supplying a control signal to the EGR valve 7 based on signals supplied from the various sensors described above. Thus, the ECU 20 corresponds to the control device for the internal combustion engine in the present invention, and functions as an EGR valve opening calculation means, an EGR valve opening correction means, a piston temperature acquisition means, and a piston temperature calculation means.

[EGR valve opening correction method]
Next, a method for correcting the EGR valve opening in the present embodiment will be described.

  In the present embodiment, the ECU 20 sets the EGR valve opening degree in the EGR valve 7 based on the piston temperature in the engine 4 when the engine 4 is warmed up. Specifically, the ECU 20 first calculates the EGR valve opening based on the operating state of the engine 4 and the like. Specifically, the ECU 20 obtains an EGR valve opening (hereinafter referred to as “first EGR valve opening”) based on the engine speed and the fuel injection amount, and uses the first EGR valve opening. Correction is performed based on water temperature, oil temperature, hydraulic pressure, and the like (hereinafter, the EGR valve opening obtained by correcting the first EGR valve opening is referred to as “second EGR valve opening”).

  The ECU 20 further corrects the second EGR valve opening degree based on the piston temperature (hereinafter, the EGR valve opening degree obtained by correcting the second EGR valve opening degree is referred to as “third "EGR valve opening". This correction is performed because the piston temperature appropriately represents the temperature around the combustion chamber actually involved in the combustion. Therefore, in the warm-up process of the engine 4, the EGR valve is considered in consideration of the piston temperature. This is because it is considered desirable to set the opening. In other words, in the warm-up process, the water temperature may not appropriately represent the temperature around the combustion chamber. Therefore, it is better to set the EGR valve opening in consideration of not only the water temperature but also the piston temperature. It is because it is thought that it can control appropriately.

  More specifically, the ECU 20 acquires the piston temperature measured by the piston temperature sensor 15 (hereinafter referred to as “piston temperature measurement value”) and also determines the piston temperature (hereinafter referred to as “ The third EGR is calculated by correcting the second EGR valve opening described above based on the deviation between the measured piston temperature and the calculated piston temperature. Get the valve opening. By doing so, the EGR valve opening can be appropriately set in consideration of the relationship between the calculated piston temperature (piston temperature calculation value) and the actual piston temperature (piston temperature measurement value). 7 can be optimally controlled. Therefore, it is possible to effectively reduce exhaust during the warm-up process.

  Next, a method for correcting the EGR valve opening will be described more specifically with reference to FIGS.

  FIG. 2 is a diagram for explaining how to obtain the first EGR valve opening and the second EGR valve opening.

  FIG. 2A shows a map (hereinafter referred to as “EGR valve opening map”) representing the first EGR valve opening that should be set for each engine speed and fuel injection amount. Specifically, “EGRV1, EGRV2,...” In the EGR valve opening map indicates the first EGR valve opening that should be set for each engine speed and fuel injection amount. First, the ECU 20 refers to such an EGR valve opening map to obtain a first EGR valve opening corresponding to the current engine speed and fuel injection amount. The EGR valve opening map is created by performing measurement and analysis in advance.

  FIG. 2B shows an example of a table in which a correction coefficient (water temperature correction coefficient) for correcting the first EGR valve opening is associated with the water temperature. FIG. 2C shows an example of a table in which a correction coefficient (oil temperature correction coefficient) for correcting the first EGR valve opening is associated with the oil temperature. Further, FIG. 2D shows an example of a table in which a correction coefficient (hydraulic correction coefficient) for correcting the first EGR valve opening is associated with the hydraulic pressure. By referring to such a table, a water temperature correction coefficient, an oil temperature corresponding to each of the current water temperature, oil temperature, and oil pressure (which are obtained from the water temperature sensor 12, the oil temperature sensor 13, and the oil pressure sensor 14), respectively. A correction coefficient and a hydraulic pressure correction coefficient are obtained.

  ECU20 is based on the correction coefficient obtained from each table of Drawing 2 (b)-Drawing 2 (d) to the 1st EGR valve opening degree obtained from the EGR valve opening degree map as mentioned above. By performing the correction, the second EGR valve opening is obtained. As an example, the ECU 20 uses any one of the water temperature correction coefficient, the oil temperature correction coefficient, and the hydraulic pressure correction coefficient based on the current water temperature, oil temperature, and the level (level) and magnitude relationship in the hydraulic pressure. Then, the correction is performed using the determined correction coefficient. For example, when the oil temperature is relatively low even when the water temperature is relatively high, the oil temperature correction coefficient is used instead of the water temperature correction coefficient so that the correction is performed more greatly. In another example, the ECU 20 determines which one of the water temperature correction coefficient and the oil temperature correction coefficient to use based on the operating conditions (engine speed, load, etc.), and depending on whether the piston jet is activated or not. It is determined whether or not to use a hydraulic pressure correction coefficient, and correction is performed using a correction coefficient according to the determination. That is, in addition to the correction using either the water temperature correction coefficient or the oil temperature correction coefficient, the correction using the hydraulic pressure correction coefficient is performed according to the presence or absence of the operation of the piston jet. When the piston jet is operating, it is considered that the hydraulic pressure is relatively high.

  FIG. 3 is a diagram for explaining how to obtain the calculated piston temperature value.

  FIG. 3A shows a map (hereinafter referred to as “piston temperature map”) representing the piston temperature for each engine speed and fuel injection amount. Specifically, “P1, P2,...” In the piston temperature map indicates the piston temperature for each engine speed and fuel injection amount. First, the ECU 20 refers to such a piston temperature map to obtain a piston temperature corresponding to the current engine speed and fuel injection amount. Hereinafter, the piston temperature obtained from the piston temperature map is referred to as “piston temperature map value”. Such a piston temperature map is created by performing measurement and analysis in advance.

  FIG. 3B shows an example of a table in which a correction coefficient (water temperature correction coefficient) for correcting the piston temperature map value is associated with the water temperature. FIG. 3C shows an example of a table in which a correction coefficient (oil temperature correction coefficient) for correcting the piston temperature map value is associated with the oil temperature. FIG. 3D shows an example of a table in which a correction coefficient (hydraulic correction coefficient) for correcting the piston temperature map value is associated with the hydraulic pressure. By referring to such a table, a water temperature correction coefficient, an oil temperature corresponding to each of the current water temperature, oil temperature, and oil pressure (which are obtained from the water temperature sensor 12, the oil temperature sensor 13, and the oil pressure sensor 14), respectively. A correction coefficient and a hydraulic pressure correction coefficient are obtained.

  The ECU 20 corrects the piston temperature map value obtained from the piston temperature map as described above based on the correction coefficients obtained from the tables shown in FIGS. 3B to 3D. The piston temperature calculation value is obtained. As an example, the ECU 20 uses any one of the water temperature correction coefficient, the oil temperature correction coefficient, and the hydraulic pressure correction coefficient based on the current water temperature, oil temperature, and the level (level) and magnitude relationship in the hydraulic pressure. Then, the correction is performed using the determined correction coefficient. For example, when the oil temperature is relatively low even when the water temperature is relatively high, the oil temperature correction coefficient is used instead of the water temperature correction coefficient so that the correction is performed more greatly. In another example, the ECU 20 determines which one of the water temperature correction coefficient and the oil temperature correction coefficient to use based on the operating conditions (engine speed, load, etc.), and depending on whether the piston jet is activated or not. It is determined whether or not to use a hydraulic pressure correction coefficient, and correction is performed using a correction coefficient according to the determination. That is, in addition to the correction using either the water temperature correction coefficient or the oil temperature correction coefficient, the correction using the hydraulic pressure correction coefficient is performed according to the presence or absence of the operation of the piston jet.

  FIG. 4 is a diagram for explaining how to obtain the third EGR valve opening. Specifically, FIG. 4 shows a correction coefficient (hereinafter referred to as “piston temperature correction coefficient”) for further correcting the second EGR valve opening described above with respect to the deviation between the measured piston temperature value and the calculated piston temperature value. ").) Is an example of a table associated with each other. In this case, the deviation is obtained from “piston temperature measurement value−piston temperature calculation value”. From the table shown in FIG. 4, it can be seen that the absolute value of the piston temperature correction coefficient increases as the absolute value of the deviation increases. Specifically, the smaller the deviation value, the smaller the piston temperature correction coefficient, and the larger the deviation value, the larger the piston temperature correction coefficient. Thus, it is considered that the third EGR valve opening is relatively small when the deviation value is small, and the third EGR valve opening is relatively large when the deviation value is large. Note that the table as shown in FIG. 4 is created by performing measurement and analysis in advance.

  The ECU 20 calculates the deviation by subtracting the piston temperature calculation value obtained by the method shown in FIG. 3 from the piston temperature measurement value acquired from the piston temperature sensor 15, and refers to a table as shown in FIG. Thus, a piston temperature correction coefficient corresponding to the calculated deviation is obtained. Then, the ECU 20 obtains the third EGR valve opening by correcting the second EGR valve opening obtained by the method shown in FIG. 2 using the obtained piston temperature correction coefficient. .

  By controlling the EGR valve 7 based on the third EGR valve opening obtained in this way, the EGR valve 7 can be optimally controlled. Specifically, in a situation where the amount of EGR gas to be recirculated should be reduced (for example, when the piston temperature is relatively low and the engine 4 is in the warm-up process), the EGR valve opening can be set relatively small. Therefore, it is possible to effectively suppress the emission deterioration in the warm-up process. In contrast, in a situation where the amount of EGR gas to be recirculated can be increased (for example, when it can be said that the piston temperature is relatively high and the engine 4 is warmed up), the EGR valve opening is set to be relatively large. be able to.

[EGR valve opening correction processing]
Next, the EGR valve opening correction process according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing an EGR valve opening correction process according to the present embodiment. This process is repeatedly executed by the ECU 20 at a predetermined cycle.

  First, in step S101, the ECU 20 calculates the second EGR valve opening based on the engine speed, the fuel injection amount, the water temperature, the oil temperature, and the oil pressure. Specifically, the ECU 20 first obtains a first EGR valve opening corresponding to the current engine speed and fuel injection amount with reference to an EGR valve opening map as shown in FIG. . In this case, the engine speed is obtained from the speed sensor 11, and the fuel injection amount is obtained from a control signal supplied to the fuel injection valve. Then, the ECU 20 corrects the first EGR valve opening based on the current water temperature, oil temperature, and oil pressure (these are obtained from the water temperature sensor 12, the oil temperature sensor 13, and the oil pressure sensor 14). The second EGR valve opening degree is obtained by performing the operation. Specifically, the correction is performed based on the water temperature correction coefficient, the oil temperature correction coefficient, and the hydraulic pressure correction coefficient obtained from the tables as shown in FIGS. When the above process ends, the process proceeds to step S102.

  In step S102, the ECU 20 obtains a piston temperature calculation value based on the engine speed, the fuel injection amount, the water temperature, the oil temperature, and the oil pressure. Specifically, the ECU 20 first obtains a piston temperature map value corresponding to the current engine speed and fuel injection amount with reference to a piston temperature map as shown in FIG. The ECU 20 corrects the piston temperature map value based on the current water temperature, oil temperature, and oil pressure (these are obtained from the water temperature sensor 12, the oil temperature sensor 13, and the oil pressure sensor 14). Obtain the calculated piston temperature. Specifically, the correction is performed based on the water temperature correction coefficient, the oil temperature correction coefficient, and the hydraulic pressure correction coefficient obtained from the tables as shown in FIGS. When the above process ends, the process proceeds to step S103.

  In step S <b> 103, the ECU 20 acquires a piston temperature measurement value from the piston temperature sensor 15. Then, the process proceeds to step S104. In step S104, the ECU 20 calculates a deviation between the piston temperature measurement value obtained in step S103 and the piston temperature calculation value obtained in step S102. Specifically, the ECU 20 calculates the deviation by subtracting the piston temperature calculation value from the piston temperature measurement value. Then, the process proceeds to step S105.

  In step S105, the ECU 20 corrects the second EGR valve opening calculated in step S101 based on the deviation calculated in step S104. Specifically, the ECU 20 refers to a table as shown in FIG. 4 to obtain a piston temperature correction coefficient corresponding to the deviation between the piston temperature measurement value and the piston temperature calculation value. Then, the ECU 20 obtains the third EGR valve opening by correcting the second EGR valve opening using the obtained piston temperature correction coefficient. When the above process ends, the process exits the flow.

  According to such an EGR valve opening correction process, the EGR valve opening can be appropriately set based on the piston temperature that appropriately indicates the temperature around the combustion chamber actually involved in combustion. More specifically, the EGR valve 7 can be optimally controlled in consideration of the relationship between the calculated piston temperature (piston temperature calculation value) and the actual piston temperature (piston temperature measurement value).

[Modification]
In the above, although embodiment which correct | amends with respect to EGR valve opening based on piston temperature was shown, it is not limited to this. In another example, fuel injection timing, pilot injection interval, and the like can be corrected based on the piston temperature instead of the EGR valve opening. That is, based on the deviation between the piston temperature measurement value and the piston temperature calculation value as described above, the fuel injection timing, the pilot injection interval, and the like can be optimally controlled.

1 is a schematic configuration diagram of a vehicle to which an internal combustion engine control device according to an embodiment is applied. It is a figure for demonstrating how to obtain | require a 1st EGR valve opening and a 2nd EGR valve opening. It is a figure for demonstrating how to obtain | require piston temperature calculation value. It is a figure for demonstrating how to obtain | require a 3rd EGR valve opening degree. It is a flowchart which shows the EGR valve opening correction process which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Intake passage 4 Engine 5 Exhaust passage 6 EGR passage 7 EGR valve 11 Speed sensor 12 Water temperature sensor 13 Oil temperature sensor 14 Hydraulic sensor 15 Piston temperature sensor 20 ECU
50 vehicles

Claims (4)

A control device for an internal combustion engine for controlling an EGR valve provided on an EGR passage for recirculating exhaust gas from the internal combustion engine,
EGR valve opening calculation means for calculating an EGR valve opening to be set for the EGR valve based on at least the operating state of the internal combustion engine;
EGR valve opening correction means for correcting the EGR valve opening calculated by the EGR valve opening calculation means based on a piston temperature in the internal combustion engine when the internal combustion engine is warmed up. An internal combustion engine control device. Piston temperature acquisition means for acquiring a piston temperature measurement value measured by the sensor;
Piston temperature calculation means for obtaining a piston temperature calculation value based on at least the operating state of the internal combustion engine, further comprising:
The internal combustion engine control according to claim 2, wherein the EGR valve opening correction means corrects the EGR valve opening using a deviation between the measured piston temperature value and the calculated piston temperature as the piston temperature. apparatus.   The piston temperature calculation means uses the rotation speed and the fuel injection amount as the operating state of the internal combustion engine, and calculates the piston temperature calculation value using at least one of water temperature, oil temperature, and hydraulic pressure. 3. The control device for an internal combustion engine according to 2.   The EGR valve opening calculation means calculates the EGR valve opening using at least one of a water temperature, an oil temperature, and a hydraulic pressure while using the rotational speed and the fuel injection amount as the operating state of the internal combustion engine. The control apparatus for an internal combustion engine according to any one of claims 1 to 3.

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