JP2015197072A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of preventing degradation in the fuel economy of an internal combustion engine including an EGR system and an intake throttle valve.SOLUTION: An internal combustion engine control device fixing the opening of an intake throttle valve and controlling the opening of an EGR valve to control an EGR quantity in an insensitive region in which an intake change is small relative to the opening of the intake throttle valve, comprises: means for learning a maximum value and a minimum value of an effective opening area relative to the opening of the intake throttle valve; and means for setting the opening of the intake throttle valve in the insensitive region to the opening of the intake throttle valve at which the maximum value and the minimum value are each equal to a predetermined value.

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, an exhaust gas recirculation device (hereinafter referred to as an EGR device) in which a part of the exhaust gas (hereinafter referred to as EGR gas) is recirculated to the intake system to slow down combustion and to reduce NOx by reducing the combustion temperature. .) Is known. Patent Document 1 discloses a control method for adjusting the opening of an intake throttle valve that controls the flow rate in an intake passage simultaneously with an EGR valve included in an EGR device in an internal combustion engine equipped with an EGR device. This control method is a method for performing feedback control of the EGR amount by the EGR valve by closing the intake throttle valve to a predetermined position in the insensitive region where the change in the EGR amount with respect to the opening of the intake throttle valve is small.

JP 2006-161568 A JP 2003-166445 A

  However, in the control method disclosed in Patent Document 1, since the intake throttle valve is closed at a predetermined position determined in advance, the manufacturing variation of the internal combustion engine is not taken into consideration. For this reason, depending on the internal combustion engine, the intake air may be throttled more than necessary to control the air amount, and the fuel efficiency may deteriorate.

  The present invention has been made to solve the above-described problems, and provides an internal combustion engine control device capable of preventing deterioration of fuel consumption in an internal combustion engine including an EGR device and an intake throttle valve. With the goal.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
In a control device for an internal combustion engine that controls the EGR amount by fixing the intake throttle valve opening and controlling the EGR valve opening in the insensitive region where the change in the intake amount is small with respect to the intake throttle valve opening.
Means for learning the maximum value and the minimum value of the effective opening area with respect to the intake throttle valve opening;
Means for setting the intake throttle valve opening in the insensitive region to an intake throttle valve opening at which the maximum value and the minimum value are predetermined values;
It is characterized by providing.

  According to the first aspect of the invention, it is possible to calculate the intake throttle valve opening in which the deterioration of fuel consumption is minimized for each engine with manufacturing variations.

FIG. 6 is a diagram showing an effective opening area with respect to the intake throttle valve closing degree in the first embodiment. FIG. 5 is a diagram showing a relationship between a minimum value of an effective opening area and an intake throttle valve closing degree in the first embodiment. FIG. 7 is a diagram illustrating learning and updating of an effective opening area minimum value curve in the first embodiment. FIG. 6 is a diagram showing a relationship between a maximum value of an effective opening area and an intake throttle valve closing degree in the first embodiment. FIG. 5 is a diagram illustrating learning and updating of an effective opening area maximum value curve in the first embodiment. 6 is a diagram for describing calculation of a difference between a maximum value and a minimum value of an effective opening area in the first embodiment. FIG. FIG. 6 is a diagram for explaining a difference ΔAr curve in the first embodiment. 4 is a flowchart of an intake throttle valve opening calculation routine executed by the ECU in the first embodiment.

Embodiment 1 FIG.
The engine of Embodiment 1 is a diesel engine with a turbocharger (hereinafter simply referred to as an engine). The engine includes an EGR device that recirculates EGR gas to the intake system. The EGR device includes an EGR pipe that communicates the exhaust passage and the intake passage, and an EGR valve that is provided in the EGR pipe and controls the amount of EGR. In addition, an intake throttle valve that adjusts the amount of fresh air is provided in the intake system of the engine. The intake throttle valve is provided upstream of the position where the intake passage and the EGR pipe are connected.

  In the intake system, an intake air temperature sensor is provided upstream of the intake throttle valve. Further, a boost pressure sensor is provided downstream of the intake throttle valve.

  The engine of the first embodiment is controlled by an ECU (Engine Control Unit). Various sensors such as an intake air temperature sensor and a supercharging pressure sensor are connected to the ECU. The ECU calculates the intake air temperature based on the output of the intake air temperature sensor. The ECU calculates the supercharging pressure based on the output of the supercharging pressure sensor.

  It is an object of the present invention to calculate an optimal intake throttle valve opening that takes into account the influence of engine manufacturing variations when EGR control is performed with the intake throttle valve closed at a predetermined position. For this purpose, the ECU according to the first embodiment calculates the effective opening area of the intake throttle valve, learns the maximum and minimum values of the effective opening area of the intake throttle valve with respect to the intake throttle valve opening, and the intake air. A step of calculating a minimum intake throttle valve opening for ensuring controllability of the air amount from the maximum value and the minimum value of the effective opening area of the throttle valve is executed. Hereinafter, these three steps will be described in detail.

[Calculation step of effective opening area of intake throttle valve]
The effective opening area of the intake throttle valve is calculated using a nozzle formula shown in the following formula (1). Here, dm is the target nozzle passage flow rate [kg / sec], A _eff is the effective opening area [m ² ], _Tus is the pre-nozzle temperature [K], and P _us is the pre-nozzle pressure [Pa]. ], P _ds is the nozzle post-pressure [Pa], and R is the gas constant [J / kg · K].

  Further, when the intake throttle valve effective opening area is calculated using the above equation (1), the following two cases of equation (2) and equation (3) are performed.

  FIG. 1 is a diagram showing the effective opening area with respect to the intake throttle valve closing degree in the first embodiment. FIG. 1 shows an intake throttle valve effective opening area calculated based on actual machine data of a plurality of engines. As shown in FIG. 1, the sensitivity of the effective opening area with respect to the intake throttle valve closing degree is not uniquely determined, and varies depending on the intake throttle valve closing degree. As described above, regarding the relationship of the effective opening area with respect to the intake throttle valve closing degree, the width of the effective opening area decreases as the sensitivity of the air flow rate change with respect to the intake throttle valve closing degree increases.

[Maximum and minimum learning steps for effective opening area of intake throttle valve]
FIG. 2 is a diagram showing the relationship between the minimum effective opening area and the intake throttle valve closing degree in the first embodiment. The ECU stores the minimum value of the effective opening area with respect to the intake throttle valve closing degree measured in the course of engine development. This minimum value is defined as an effective opening area minimum value curve. The ECU stores an effective opening area minimum value guard for eliminating an abnormal value of the effective opening area as shown in FIG.

  FIG. 3 is a diagram illustrating learning and updating of the effective opening area minimum value curve in the first embodiment. First, the effective opening area of the intake throttle valve is always calculated when execution conditions such as not when the engine is started and when there is no abnormality in the engine are satisfied. Next, it is determined whether the calculated effective opening area is equal to or smaller than the minimum value curve stored in the ECU. Next, it is determined whether the calculated effective opening area is equal to or larger than the minimum guard stored in the ECU. Then, as shown in FIG. 3, when the calculated effective opening area is equal to or smaller than the minimum value curve and equal to or larger than the minimum value guard, the effective opening area minimum value curve is learned and updated.

  FIG. 4 is a diagram showing the relationship between the maximum value of the effective opening area and the intake throttle valve closing degree in the first embodiment. The ECU stores the maximum value of the effective opening area with respect to the intake throttle valve closing degree measured in the course of engine development. This maximum value is defined as an effective opening area maximum value curve. Further, the ECU stores an effective opening area maximum value guard for eliminating an abnormal value of the effective opening area as shown in FIG.

  FIG. 5 is a diagram illustrating learning and updating of the effective opening area maximum value curve in the first embodiment. First, it is determined whether the calculated effective opening area is equal to or greater than the maximum value curve stored in the ECU. Next, it is determined whether the calculated effective opening area is equal to or less than the maximum guard stored in the ECU. Then, as shown in FIG. 5, when the calculated effective opening area is not less than the maximum value curve and not more than the maximum value guard, the effective opening area maximum value curve is learned and updated.

[Intake throttle valve opening calculation step]
FIG. 6 is a diagram for explaining calculation of a difference between the maximum value and the minimum value of the effective opening area in the first embodiment. The ECU calculates a difference ΔAr (hereinafter referred to as a difference ΔAr) between the effective opening area maximum value curve and the effective opening area minimum value curve at the calculated intake throttle valve opening.

  FIG. 7 is a diagram for explaining the difference ΔAr curve in the first embodiment. The ECU calculates the difference ΔAr for each intake throttle valve opening, and creates a difference ΔAr curve. As shown in FIG. 7, there is a difference between the difference ΔAr curve obtained in the engine development process and the difference ΔAr curve of the engine having manufacturing variations.

  The ECU stores a predetermined value ΔArref of an effective opening area when the intake throttle valve is closed at a predetermined position and EGR control is performed. Here, the intake throttle valve opening for obtaining the predetermined value ΔArref determined in the development process is different from the intake throttle valve opening of the engine having manufacturing variations. Therefore, the intake throttle valve opening is corrected so that the predetermined value ΔArref determined in the development process can be obtained even in an engine with manufacturing variations.

  By performing the control according to the first embodiment, it is possible to calculate the intake throttle valve opening degree in which the deterioration of fuel consumption is suppressed to the minimum for each engine with manufacturing variations.

[Intake throttle valve opening calculation routine]
FIG. 8 is a flowchart of an intake throttle valve opening degree calculation routine executed by the ECU in the first embodiment. The ECU has a memory for storing this routine. The ECU has a processor for executing the stored routine.

  First, the ECU determines whether or not the engine is starting (S100). When the ECU determines that the engine is at the time of starting, the ECU ends the control.

  On the other hand, if the ECU determines that the engine is not at the time of starting, it determines whether or not an abnormality has occurred in the engine (S102). When the ECU determines that an abnormality has occurred in the engine, the ECU ends the control.

  On the other hand, if the ECU determines that there is no abnormality in the engine, the ECU calculates the intake throttle valve effective opening area (S104). The ECU calculates the effective opening area using the equation (1) described above.

  Next, the ECU determines whether or not the effective opening area is less than or equal to the minimum value curve (S106). If the ECU determines that the effective opening area is equal to or less than the minimum value curve, the ECU determines whether the effective opening area is equal to or greater than the minimum value guard (S108). When the ECU determines that the effective opening area is smaller than the minimum guard, the routine returns to the starting point.

  On the other hand, when the ECU determines that the effective opening area is equal to or greater than the minimum guard, the ECU learns a minimum curve of the effective opening area (S110).

  When it is determined in S106 that the effective opening area is larger than the minimum value curve, the ECU determines whether or not the effective opening area is equal to or larger than the maximum value curve (S112). When it is determined that the effective opening area is equal to or greater than the maximum value curve, the ECU determines whether the effective opening area is equal to or less than the maximum guard (S114). When the ECU determines that the effective opening area is larger than the maximum guard, the routine returns to the starting point.

  On the other hand, when the ECU determines that the effective opening area is equal to or less than the maximum guard, the ECU learns the maximum curve of the effective opening area (S116).

  When it is determined in S112 that the effective opening area is smaller than the maximum value curve, the ECU calculates the intake throttle valve opening in the dead area (S118).

  Next, the ECU determines whether or not it is normal combustion (S120). If the ECU determines that the combustion is not normal, the routine returns to the starting point.

  On the other hand, when it is determined in S120 that the combustion is normal combustion, the ECU determines whether or not it is a dead area (S122). When the ECU determines that it is not the insensitive area, the routine returns to the starting point.

  On the other hand, if the ECU determines in S122 that it is the insensitive area, the ECU applies the intake throttle valve opening in the insensitive area (S124).

  Next, the ECU determines whether or not the engine is stopped (S126). If the ECU determines that the engine is not stopped, the routine returns to the starting point.

  On the other hand, when the ECU determines that the engine is stopped, the ECU ends the control.

Claims (1)

In a control device for an internal combustion engine that controls the EGR amount by fixing the intake throttle valve opening and controlling the EGR valve opening in the insensitive region where the change in the intake amount is small with respect to the intake throttle valve opening.
Means for learning the maximum value and the minimum value of the effective opening area with respect to the intake throttle valve opening;
Means for setting the intake throttle valve opening in the insensitive region to an intake throttle valve opening at which the maximum value and the minimum value are predetermined values;
A control device for an internal combustion engine, comprising:

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