JP2016194291A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration in fuel economy while securing control responsiveness before and after changeover, in an internal combustion engine which can switch between fresh air amount control using a diesel throttle valve and fresh air amount control using an EGR valve.SOLUTION: When a Dth-valve fore-and-aft pressure difference reaches a Dth-valve minimum fore-and-aft pressure difference or lower during the execution of Dth-valve fresh air amount control for controlling a fresh air amount by using a Dth-valve, a control device switches control to EGR-valve fresh air amount control for controlling the fresh air amount by using an EGR valve. Furthermore, when an EGR-valve fore-and-aft pressure difference reaches an EGR-valve minimum fore-and-aft pressure difference or lower during the execution of EGR-valve fresh air amount control, the control device switches control to Dth-valve fresh air amount control. The control device performs control so that the EGR-valve fore-and-aft pressure difference reaches the EGR-valve minimum fore-and-aft pressure difference during the execution of the Dth-valve fresh air amount control, and performs control so that the Dth-valve fore-and-aft pressure difference reaches the Dth-valve minimum fore-and-aft pressure difference during the execution of the EGR-valve fresh air amount control.SELECTED DRAWING: Figure 2

Description

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

  Conventionally, for example, Japanese Patent Application Laid-Open No. 2003-166445 discloses a technique related to EGR amount control of a diesel engine equipped with an EGR device. In this technique, when both the EGR valve and the intake throttle valve are feedback controlled, the target opening of the intake throttle valve is constantly calculated even during the feedback control by the EGR valve, and the actual intake throttle valve during that time is calculated. The valve opening is fixed at full open. As a result, when the control by the EGR valve is switched to the control by the intake throttle valve, the intake throttle valve starts operating from the optimal target opening that has already been calculated, so that torque shock due to switching is prevented.

  In the technique disclosed in Patent Document 1 described above, when the EGR amount is still insufficient even when the EGR valve is fully opened, the EGR valve is held fully open, while the intake air throttle is gradually reduced as the intake air amount decreases. The valve is closed. Thereby, since the differential pressure before and after the EGR valve can be increased, a large amount of EGR can be obtained.

JP 2003-166445 A JP 2007-270642 A JP 2009-185732 A JP 2006-161568 A

  In order to suppress the deterioration of emissions, it is required to control the air amount of the internal combustion engine to a target value with high accuracy by operating a control valve such as an EGR valve or a diesel throttle valve. One of the important factors for such a requirement is to ensure control responsiveness and convergence of the control valve. The parameter that affects the control responsiveness and convergence of the control valve is the gas differential pressure before and after the control valve. If this differential pressure is more than a certain value determined by the characteristics of the valve, control of the valve Responsiveness is guaranteed.

  However, in the above prior art, no consideration is given to the differential pressure across the EGR valve and the intake throttle valve. The “front-rear differential pressure” expressed in this specification is the difference between the front pressure and the rear pressure when the upstream side gas pressure of the target valve is the front pressure and the downstream side gas pressure is the rear pressure. It refers to pressure. For this reason, for example, in the control state in which the EGR valve is fully opened, there is a possibility that the control responsiveness cannot be ensured due to insufficient differential pressure across the EGR valve. Further, in the above-described conventional technology, when switching from the EGR valve control to the intake throttle valve control, the intake throttle valve is in a fully opened state. For this reason, immediately after the control of the intake throttle valve is started, the control responsiveness of the intake throttle valve cannot be ensured, and there is a possibility that the target value cannot be quickly converged. As described above, in the conventional technique, when switching between control of the EGR valve and control of the intake throttle valve, there is a possibility that control responsiveness before and after switching cannot be secured.

  If attention is paid only to the control response of the control valve, it is sufficient to keep the differential pressure across the control valve at a large level at all times. However, in this case, deterioration of fuel consumption due to increased flow resistance is a problem. It becomes. Thus, the control responsiveness and fuel consumption of the control valve are in a trade-off relationship, and it is desired to establish a technology that makes these compatible.

  The present invention has been made in view of the above-described problems, and is an internal combustion engine capable of switching between control of fresh air amount using a diesel throttle valve and control of fresh air amount using an EGR valve. An object of the present invention is to provide a control device for an internal combustion engine that can suppress deterioration of fuel consumption while ensuring the control response of the engine.

In order to achieve the above object, the first invention provides
A throttle valve disposed in the intake passage, an EGR passage for recirculating exhaust gas downstream of the throttle valve in the intake passage, and an EGR valve disposed in the EGR passage, Throttle valve fresh air amount control for determining the degree of closing of the throttle valve by feedback control so that the state amount correlated with the fresh air amount approaches the target value, and the state amount correlated with the fresh air amount or the fresh air amount In an internal combustion engine control device configured to execute EGR valve fresh air amount control that determines the opening degree of the EGR valve by feedback control so as to approach a target value,
During execution of the EGR valve fresh air amount control, a first differential pressure, which is a difference between a gas pressure upstream of the throttle valve and a gas pressure downstream of the throttle valve in the intake passage, becomes a throttle valve target differential pressure. During the execution of the throttle valve differential pressure control to be controlled and the throttle valve fresh air amount control, a second differential pressure that is a difference between the gas pressure on the upstream side of the EGR valve and the gas pressure on the downstream side in the EGR passage is Differential pressure control means for performing EGR valve differential pressure control for controlling the EGR valve to achieve a target differential pressure;
When the first differential pressure falls below the throttle valve target differential pressure during execution of the throttle valve fresh air amount control, switching to the EGR valve fresh air amount control is performed, and during execution of the EGR valve fresh air amount control, Switching control means for switching to the throttle valve fresh air amount control when the second differential pressure is lower than the EGR valve target differential pressure;
It is characterized by having.

According to a second invention, in the first invention,
The differential pressure control means comprises a closing degree calculating means for calculating a closing degree for throttle valve differential pressure control, which is a closing degree of the throttle valve for the first differential pressure to become the throttle valve target differential pressure, The throttle valve differential pressure control is configured to control the throttle valve closing degree to the throttle valve differential pressure control closing degree,
The switching control means switches to the EGR valve fresh air amount control when the closing degree of the throttle valve is lower than the throttle valve differential pressure control closing degree during execution of the throttle valve fresh air amount control. It is characterized by being composed.

According to a third invention, in the second invention,
The closing degree calculating means is configured to calculate the closing degree for the throttle valve differential pressure control using an actual fresh air amount of the internal combustion engine and a state quantity of gas before and after the throttle valve. It is a feature.

According to a fourth invention, in the second invention,
The closing degree calculating means is configured to calculate the closing degree for controlling the throttle valve differential pressure based on an operating condition of the internal combustion engine and an environmental condition including a cooling water temperature or an atmospheric pressure or an atmospheric temperature. It is characterized by.

According to a fifth invention, in the first invention,
The differential pressure control means obtains the actual value of the first differential pressure, and in the throttle valve differential pressure control, the throttle valve closing degree is determined by feedback control so that the actual value approaches the throttle valve target differential pressure. It is characterized by being configured to determine.

A sixth invention is any one of the second to fifth inventions,
Throttle valve target differential pressure calculating means for calculating the throttle valve target differential pressure according to the opening degree of the EGR valve is further provided.

A seventh invention is the invention according to any one of the first to sixth inventions,
The differential pressure control means includes an opening degree calculation means for calculating an opening degree for EGR valve differential pressure control, which is an opening degree of the EGR valve for the second differential pressure to become the EGR valve target differential pressure, The EGR valve differential pressure control is configured to control the opening of the EGR valve to the EGR valve differential pressure control opening,
The switching control means switches to the throttle valve fresh air amount control when the opening degree of the EGR valve becomes larger than the opening degree for EGR valve differential pressure control during execution of the EGR valve fresh air amount control. It is characterized by being composed.

In an eighth aspect based on the seventh aspect,
The opening degree calculation means is configured to calculate the opening degree for EGR valve differential pressure control using an actual EGR gas amount of the internal combustion engine and a gas state quantity before and after the EGR valve. It is a feature.

According to a ninth invention, in the seventh invention,
The opening calculation means is configured to calculate the EGR valve differential pressure control opening based on operating conditions of the internal combustion engine and environmental conditions including cooling water temperature, atmospheric pressure, or atmospheric temperature. It is characterized by.

A tenth aspect of the invention is any one of the first to sixth aspects of the invention,
The differential pressure control means obtains an actual value of the second differential pressure, and controls the opening degree of the EGR valve by feedback control so that the actual value approaches the EGR valve target differential pressure in the EGR valve differential pressure control. It is characterized by being configured to determine.

The eleventh invention is the seventh to tenth invention,
The apparatus further comprises EGR valve target differential pressure calculating means for calculating the EGR valve target differential pressure in accordance with the degree of closing of the throttle valve.

  According to the first aspect of the present invention, in the fresh air amount control for bringing the fresh air amount or the state amount correlated with the fresh air amount close to the target value, the throttle valve fresh air amount control for determining the closing degree of the throttle valve by feedback control; The EGR valve fresh air amount control that determines the opening degree of the EGR valve by feedback control is configured to be switchable. According to the first aspect of the present invention, during the execution of the throttle valve fresh air amount control, the second differential pressure, which is the differential pressure across the EGR valve, is controlled to become the EGR valve target differential pressure, and the EGR valve fresh air is controlled. During execution of the amount control, control is performed so that the first differential pressure, which is the differential pressure across the throttle valve, becomes the throttle valve target differential pressure. Further, according to the first aspect of the present invention, when the front-rear differential pressure of the throttle valve falls below the throttle valve target differential pressure during execution of the throttle valve fresh air amount control, the EGR valve fresh air is controlled from the throttle valve fresh air amount control. When the EGR valve fresh air amount control is performed and the differential pressure before and after the EGR valve falls below the EGR valve target differential pressure, the EGR valve fresh air amount control is changed to the throttle valve fresh air amount control. Switching to is performed. The differential pressure across the valve used for the new air volume control is an index as to whether or not control response and convergence can be ensured. Further, the differential pressure across the valve not used for the fresh air amount control is an index of fuel consumption. According to the present invention, when the new air amount control is switched, control is performed so that the differential pressure before and after these valves becomes the target differential pressure, respectively. Control which suppresses deterioration can be performed.

  According to the second aspect of the invention, the degree of closing for throttle valve differential pressure control is calculated so that the differential pressure across the throttle valve becomes the throttle valve target differential pressure. When the throttle valve closing degree is lower than the throttle valve differential pressure control closing degree during execution of the throttle valve fresh air amount control, the throttle valve fresh air amount control is switched to the EGR valve fresh air amount control. Therefore, according to the present invention, it is possible to accurately determine when the throttle valve differential pressure becomes the throttle valve target differential pressure based on the throttle valve closing degree. Switching from the quantity control to the EGR valve fresh air quantity control can be performed.

  According to the third aspect of the invention, based on the actual fresh air amount and the state quantity of the gas before and after the throttle valve, the throttle valve differential pressure control closing degree so that the differential pressure across the throttle valve becomes the throttle valve target differential pressure. Is calculated. When correction for adapting to environmental conditions is performed in the fresh air amount control of the internal combustion engine, the effect of the correction is reflected on the actual fresh air amount. For this reason, according to the present invention, it is possible to calculate the throttle valve differential pressure control closing degree corresponding to the environmental condition based on the operating condition including the actual fresh air amount.

  According to the fourth aspect of the present invention, the throttle valve differential for making the front-rear differential pressure of the throttle valve the throttle valve target differential pressure based on the operating conditions of the internal combustion engine and the environmental conditions including the cooling water temperature, atmospheric pressure or atmospheric temperature. The degree of closure for pressure control is calculated. Therefore, according to the present invention, it is possible to calculate the throttle valve differential pressure control closing degree in which the environmental conditions are reflected.

  According to the fifth aspect, the differential pressure across the throttle valve during execution of the EGR valve fresh air amount control is controlled to the throttle valve target differential pressure by feedback control. For this reason, according to the present invention, the differential pressure across the throttle valve when switching to the throttle valve fresh air amount control can be brought close to the throttle valve target differential pressure with high accuracy.

  According to the sixth aspect, the throttle valve target differential pressure is calculated according to the opening degree of the EGR valve. The smaller the opening degree of the EGR valve, the lower the possibility that the switching from the EGR valve fresh air amount control to the throttle valve fresh air amount control will be immediately performed. That is, the opening degree of the EGR valve serves as an index for the possibility of switching the new air amount control from the EGR valve new air amount control to the throttle valve new air amount control. For this reason, according to the present invention, it is possible to calculate the throttle valve target differential pressure in consideration of the possibility of switching the fresh air amount control.

  According to the seventh aspect, the opening degree for EGR valve differential pressure control is calculated so that the differential pressure across the EGR valve becomes the EGR valve target differential pressure. When the opening degree of the EGR valve becomes larger than the opening degree for EGR valve differential pressure control during the execution of the EGR valve fresh air quantity control, the EGR valve fresh air quantity control is switched to the throttle valve fresh air quantity control. Therefore, according to the present invention, it is possible to accurately determine the time when the differential pressure across the EGR valve becomes the EGR valve target differential pressure based on the opening degree of the EGR valve. It is possible to switch from the amount control to the throttle valve fresh air amount control.

  According to the eighth invention, based on the actual EGR gas amount and the state amount of the gas before and after the EGR valve, the opening for EGR valve differential pressure control so that the differential pressure before and after the EGR valve becomes the EGR valve target differential pressure Is calculated. When correction for adapting to environmental conditions is performed in the fresh air amount control of the internal combustion engine, the effect of the correction is reflected on the actual fresh air amount. Therefore, according to the present invention, the EGR valve differential pressure control opening corresponding to the environmental condition can be calculated based on the operating condition including the actual fresh air amount.

  According to the ninth aspect of the present invention, the EGR valve differential for causing the differential pressure across the EGR valve to become the EGR valve target differential pressure based on the operating conditions of the internal combustion engine and the environmental conditions including the cooling water temperature, atmospheric pressure or atmospheric temperature. The pressure control opening is calculated. For this reason, according to this invention, the opening degree for EGR valve differential pressure control in which the environmental condition was reflected is computable.

  According to the tenth aspect, the differential pressure across the EGR valve during execution of the throttle valve fresh air amount control is controlled to the EGR valve target differential pressure by feedback control. For this reason, according to the present invention, the differential pressure before and after the EGR valve when switching to the EGR valve fresh air amount control can be accurately brought close to the EGR valve target differential pressure.

  According to the eleventh aspect of the invention, the EGR valve target differential pressure is calculated according to the closing degree of the throttle valve. The greater the degree of closing of the throttle valve (closed side), the lower the possibility that the switching from the throttle valve fresh air amount control to the EGR valve fresh air amount control will be immediately performed. In other words, the degree of closing of the throttle valve is an index for achieving a possibility that the fresh air amount control is switched from the throttle valve fresh air amount control to the EGR valve fresh air amount control. For this reason, according to the present invention, it is possible to calculate the EGR valve target differential pressure in consideration of the possibility of switching the fresh air amount control.

It is a figure which shows the structure of the engine system to which the control apparatus of Embodiment 1 of this invention is applied. It is a time chart which shows the change of various state quantities at the time of switching of a feedback control function. It is a figure for demonstrating switching of the feedback control function with respect to driving | running conditions. It is a figure which shows the map which prescribed | regulated the target Dth valve front-back differential pressure corresponding to an EGR valve actual opening. It is a figure which shows the map which prescribed | regulated the target EGR valve front-back differential pressure corresponding to Dth valve actual closing degree. It is the control block diagram which extracted the functional block for calculating the minimum Dth valve closing degree A among the control functions with which ECU is provided. It is the control block diagram which extracted the functional block for calculating the largest EGR valve opening degree B among the control functions with which ECU is provided. It is a flowchart which shows the first half part of the routine for the new air quantity control performed by the control apparatus of Embodiment 1 of this invention. It is a flowchart which shows the second half part of the routine for the new air quantity control performed by the control apparatus of Embodiment 1 of this invention. It is a figure which shows the structure of the engine system with which the control apparatus of Embodiment 2 of this invention is applied. It is the control block diagram which extracted the functional block for calculating the minimum Dth valve closing degree A among the control functions with which ECU of Embodiment 2 of this invention is provided. It is the control block diagram which extracted the functional block for calculating the maximum EGR valve opening degree B among the control functions with which ECU of Embodiment 2 of this invention is provided. It is a flowchart which shows the first half part of the routine for the new air quantity control performed by the control apparatus of Embodiment 2 of this invention. It is a figure which shows the structure of the engine system with which the control apparatus of Embodiment 3 of this invention is applied. It is a flowchart which shows the first half part of the routine for the new air quantity control performed by the control apparatus of Embodiment 3 of this invention. It is a flowchart which shows the second half part of the routine for the new air quantity control performed by the control apparatus of Embodiment 3 of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram showing a configuration of an engine system to which a control device according to Embodiment 1 of the present invention is applied. The internal combustion engine according to the present embodiment is a diesel engine with a turbocharger (hereinafter simply referred to as “engine”). The engine body 2 is provided with four cylinders in series, and an injector 8 is provided for each cylinder. An intake manifold 4 and an exhaust manifold 6 are attached to the engine body 2. An intake passage 10 through which fresh air taken in from the air cleaner 20 flows is connected to the intake manifold 4. A turbocharger compressor 14 is attached to the intake passage 10. A diesel throttle valve (hereinafter also referred to as “Dth valve”) 24 is provided downstream of the compressor 14 in the intake passage 10. An intercooler 22 is provided between the compressor 14 and the Dth valve 24 in the intake passage 10. The exhaust manifold 6 is connected to an exhaust passage 12 for releasing the exhaust gas emitted from the engine body 2 into the atmosphere. A turbocharger turbine 16 is attached to the exhaust passage 12. The turbocharger is a variable displacement type, and the turbine 16 is provided with a variable nozzle 18. A catalyst device 26 for purifying exhaust gas is provided downstream of the turbine 16 in the exhaust passage 12.

  The engine according to the present embodiment includes an EGR device that recirculates exhaust gas from the exhaust system to the intake system. In the EGR device, a position downstream of the Dth valve 24 in the intake passage 10 and the exhaust manifold 6 are connected by an EGR passage 30. An EGR valve 32 is provided in the EGR passage 30. An EGR cooler 34 is provided on the exhaust side of the EGR valve 32 in the EGR passage 30. The EGR passage 30 is provided with a bypass passage 36 that bypasses the EGR cooler 34. A bypass valve 38 that switches the direction in which the exhaust gas flows is provided at a location where the bypass passage 36 branched from the EGR passage 30 joins the EGR passage 30 again.

  The engine system according to the present embodiment includes an ECU (Electronic Control Unit) 50. The ECU 50 is a control device that comprehensively controls the entire engine system, and the control device according to the present invention is embodied as one function of the ECU 50.

  The ECU 50 captures and processes a sensor signal provided in the engine system. Sensors are installed in various parts of the engine system. An air flow meter 54 for detecting the actual fresh air amount “gadly” is attached to the intake passage 10 downstream of the air cleaner 20. Further, a temperature sensor 56 for detecting the pre-Dth valve gas temperature “thia” and a pressure sensor 58 for detecting the pre-Dth valve gas pressure “pia” are attached to the intake passage 10 upstream of the Dth valve 24. It has been. The Dth valve 24 is provided with an opening degree sensor 60 for detecting the actual closing degree of the Dth valve. An intake pressure sensor 62 for detecting the intake pressure “pim” is attached to the intake passage 10 downstream of the Dth valve 24. The intake manifold 4 is provided with a temperature sensor 72 for detecting the intake manifold gas temperature. Further, a pressure sensor 64 for detecting the gas pressure “pegr” before the EGR valve and a temperature sensor 66 for detecting the gas temperature “thegr” before the EGR valve are attached to the EGR passage 30 upstream of the EGR valve 32. It has been. Further, the EGR valve 32 is provided with an opening degree sensor 68 for detecting the actual opening degree of the EGR valve. Further, a rotation speed sensor 52 that detects the rotation speed of the crankshaft, an accelerator opening sensor 70 that outputs a signal corresponding to the opening of the accelerator pedal, and the like are also attached. The ECU 50 processes the signals of the acquired sensors and operates the actuators according to a predetermined control program. The actuator operated by the ECU 50 includes the variable nozzle 18, the injector 8, the EGR valve 32, the Dth valve 24, and the like. There are many actuators and sensors connected to the ECU 50 other than those shown in the figure, but the description thereof is omitted in this specification.

[Operation of Embodiment 1]
The engine control executed by the ECU 50 includes new air amount control. In the fresh air amount control of the present embodiment, the Dth valve 24 or the EGR valve is controlled by feedback control so that the actual fresh air amount or the state quantity such as the actual EGR rate and the actual EGR gas amount correlated therewith becomes a target value. 32 operation amounts are determined.

  Here, if the operation amount of the Dth valve 24 and the operation amount of the EGR valve 32 are fed back simultaneously, the controllability is deteriorated due to interference. Accordingly, in the new air amount control of the present embodiment, the feedback control of the new air amount using the Dth valve 24 (hereinafter referred to as “Dth valve new air amount control”) and the new air amount using the EGR valve 32 are performed. The feedback control (hereinafter referred to as “EGR valve fresh air amount control”) is switched and executed.

  The control responsiveness and convergence during execution of the Dth valve fresh air amount control are the pressure difference between the gas pressure on the upstream side of the Dth valve 24 and the gas pressure on the downstream side in the intake passage 10 (hereinafter referred to as “before and after the Dth valve”). As the pressure difference (referred to as “differential pressure”) becomes smaller, it changes in a worsening direction. For this reason, when switching the feedback control function from the Dth valve fresh air amount control to the EGR valve fresh air amount control, the differential pressure before and after the Dth valve is performed within a range having a differential pressure capable of ensuring control responsiveness. Is required. However, when the feedback control function is switched from the Dth valve fresh air amount control to the EGR valve fresh air amount control within the range of the differential pressure in which the Dth valve front and rear differential pressure can ensure control responsiveness, the Dth valve front and rear difference As the pressure increases, the flow path resistance increases, leading to deterioration in fuel consumption.

  Therefore, in the new air amount control of the present embodiment, the minimum differential pressure (hereinafter referred to as “Dth valve minimum front / rear differential pressure”) that allows the Dth valve front / rear differential pressure to ensure control responsiveness during execution of the Dth valve fresh air amount control. In this case, the feedback control function is switched from the Dth valve fresh air amount control to the EGR valve fresh air amount control. Similarly, when the feedback control function is switched from the EGR valve fresh air amount control to the Dth valve fresh air amount control, the EGR valve new air amount control on the upstream side of the EGR valve 32 in the EGR passage 30 is also executed. The differential pressure between the gas pressure and the downstream gas pressure (hereinafter referred to as "EGR valve differential pressure before and after") is the minimum differential pressure that can ensure control response (hereinafter referred to as "EGR valve minimum differential pressure before and after"). When the voltage drops further, the feedback control function is switched.

  By the way, in switching the feedback control function from Dth valve fresh air amount control to EGR valve fresh air amount control, if the EGR valve front-rear differential pressure at the time of switching is not controlled to the EGR valve minimum front-rear differential pressure, the control immediately after switching is performed. It will cause deterioration of responsiveness and fuel consumption. Therefore, in the new air amount control of the present embodiment, when switching the feedback control function from the Dth valve fresh air amount control to the EGR valve new air amount control, the EGR valve front-rear differential pressure at the time of switching is changed to the EGR valve minimum front-rear differential pressure. Differential pressure control (hereinafter referred to as “EGR valve differential pressure control”) is performed. Similarly, in switching the feedback control function from the EGR valve fresh air amount control to the Dth valve fresh air amount control, the differential pressure control for keeping the Dth valve front-rear differential pressure at the time of switching the Dth valve minimum front-rear differential pressure. (Hereinafter referred to as “Dth valve differential pressure control”).

  Next, referring to the time chart, the switching of the feedback control function and the differential pressure control in the fresh air amount control of the present embodiment will be described in detail. FIG. 2 is a time chart showing changes in various state quantities when the feedback control function is switched. As shown in this figure, in the Dth valve fresh air amount control, the Dth valve closing degree is determined by feedback control so that the actual fresh air amount that is the actual value of the fresh air amount approaches the target fresh air amount that is the target value. The Further, during the execution of the Dth valve fresh air amount control, the EGR valve differential pressure control is executed in parallel. In the EGR valve differential pressure control, the EGR valve opening degree is manipulated so that the EGR valve front-rear differential pressure approaches the EGR valve minimum front-rear differential pressure. Details of EGR valve differential pressure control will be described later.

  When the target fresh air amount increases in the Dth valve fresh air amount control, the Dth valve closing degree decreases (changes to the open side) corresponding to the increase in the target fresh air amount. At this time, the differential pressure before and after the Dth valve decreases corresponding to the decrease in the Dth valve closing degree. When the Dth valve front-rear differential pressure is lower than the Dth valve minimum front-rear differential pressure, the new air amount control is switched from the Dth valve new air amount control to the EGR valve new air amount control. The EGR valve differential pressure before and after switching is controlled to the minimum EGR valve differential pressure by EGR valve differential pressure control.

  When the EGR valve fresh air amount control is started, the EGR valve opening degree is determined by feedback control so that the actual fresh air amount approaches the target fresh air amount. Further, during the execution of the EGR valve fresh air amount control, the Dth valve differential pressure control is executed in parallel. In the Dth valve differential pressure control, the Dth valve closing degree is operated so that the Dth valve differential pressure before and after approaches the Dth valve minimum differential pressure. Details of the Dth valve differential pressure control will be described later.

  After switching to the EGR valve fresh air amount control, the EGR valve opening degree decreases (changes to the closed side) corresponding to the increase in the target fresh air amount. During this time, the Dth valve front-rear differential pressure is maintained at the Dth valve minimum front-rear differential pressure by Dth valve differential pressure control.

  Thereafter, when the target fresh air amount decreases in the EGR valve fresh air amount control, the EGR valve opening degree increases (changes to the open side) corresponding to the decrease in the target fresh air amount. At this time, the EGR valve front-rear differential pressure decreases corresponding to the increase in the EGR valve opening. When the EGR valve front-rear differential pressure is lower than the EGR valve minimum front-rear differential pressure capable of ensuring control responsiveness, the feedback control function is switched from EGR valve fresh air amount control to Dth valve fresh air amount control.

  According to the above-described new air amount control, in the process of increasing the fresh air amount, the EGR valve front / rear differential pressure is changed from the Dth valve fresh air amount control in the state where the Dth valve front / rear differential pressure is the Dth valve minimum front / rear differential pressure. It is switched to the EGR valve fresh air amount control in a state where the differential pressure is the minimum. Further, according to the above-described new air amount control, in the process of reducing the new air amount, the DTH valve front / rear differential pressure is changed from the EGR valve fresh air amount control in the state where the EGR valve front / rear differential pressure is the EGR valve minimum front / rear differential pressure. The control is switched to the Dth valve fresh air amount control in the state of the Dth valve minimum front-rear differential pressure. As a result, it is possible to suppress deterioration of control responsiveness before and after switching of the feedback control function, and to suppress deterioration of fuel consumption to a minimum.

  Here, in the time chart shown in FIG. 2, in the Dth valve differential pressure control during the execution of the EGR valve fresh air amount control, the Dth valve closing degree is controlled so that the Dth valve front-rear differential pressure becomes the Dth valve minimum front-rear differential pressure. doing. However, when the EGR valve fresh air amount control is being executed and the operating condition is such that the feedback control function is unlikely to immediately switch to the Dth valve fresh air amount control, the difference between the front and rear of the Dth valve is prepared in preparation for the switching of the feedback control function. The need to maintain the pressure at the minimum differential pressure across the Dth valve is low. That is, if the Dth valve closing degree can be further reduced (changed to the open side) under such operating conditions, fuel efficiency can be improved by reducing the flow resistance.

  FIG. 3 is a diagram for explaining switching of the feedback control function with respect to the driving conditions. As shown in this figure, in the new air amount control of the present embodiment, when the rotational speed and the injection amount increase, the feedback control function is switched from the Dth valve fresh air amount control to the EGR valve new air amount control. After switching to the EGR valve fresh air amount control, the EGR valve opening decreases (changes to the closed side) as the rotational speed and the injection amount increase. From this, the EGR valve opening can be used as an index for determining the possibility that the feedback control function is switched from the EGR valve fresh air amount control to the Dth valve fresh air amount control.

  Therefore, in the new air amount control of the present embodiment, the target value of the Dth valve differential pressure control in the Dth valve differential pressure control (hereinafter referred to as “target”) based on the EGR valve opening during execution of the EGR valve fresh air amount control. This is referred to as “Dth valve front-rear differential pressure”). FIG. 4 is a diagram showing a map defining the target Dth valve front-rear differential pressure corresponding to the actual EGR valve opening. As shown in the figure, the target Dth valve front-rear differential pressure can be calculated based on the actual EGR valve opening. More specifically, the target Dth valve front-rear differential pressure is basically calculated as the value of the Dth valve minimum front-rear differential pressure, and a partial region where the feedback control function is unlikely to be switched, that is, the EGR valve actual opening is a predetermined opening. It is calculated so as to be smaller than the Dth valve minimum front-rear differential pressure in a partial region closer to α. The predetermined opening α is determined by taking into account the control calculation cycle of the Dth valve differential pressure control, the control calculation cycle of the EGR valve fresh air amount control, the control responsiveness of the Dth valve 24 and the EGR valve 32, and the like. Any EGR opening that can control the Dth valve front-rear differential pressure to the Dth valve minimum front-rear differential pressure during the period until the front-rear differential pressure drops below the EGR valve minimum front-rear differential pressure may be used. According to such control, the Dth valve front-rear differential pressure at the time of switching the feedback control function realizes the Dth valve minimum front-rear differential pressure, while the Dth valve front-rear differential pressure at the time when the feedback control function does not switch is the Dth valve minimum front-rear differential pressure. The pressure can be reduced more than the differential pressure. Thereby, the fuel consumption can be further improved while ensuring the control response before and after the switching of the feedback control function.

  In the above-described new air amount control, in the Dth valve differential pressure control during the execution of the EGR valve fresh air amount control, the control for changing the differential pressure across the Dth valve to a value smaller than the minimum differential pressure before and after the Dth valve. In the EGR valve differential pressure control during the execution of the Dth valve fresh air amount control, similarly, the EGR valve front-rear differential pressure is changed to a value smaller than the EGR valve minimum front-rear differential pressure. Control can be performed. In this case, in a region where the feedback control function is unlikely to be switched, that is, in a partial region where the Dth valve actual closing degree is on the closed side, the target value of the EGR valve front-rear differential pressure (hereinafter referred to as “target EGR valve front-rear differential pressure”). The target EGR valve front-rear differential pressure corresponding to the Dth valve actual closing degree may be calculated using a map that is defined to be smaller than the EGR valve minimum front-rear differential pressure. Hereinafter, calculation of the target EGR valve front-rear differential pressure will be described in more detail.

  FIG. 5 is a diagram showing a map defining the target EGR valve front-rear differential pressure corresponding to the Dth valve actual closing degree. As shown in this figure, the target EGR valve front-rear differential pressure can be calculated based on the Dth valve actual closing degree. More specifically, the target EGR valve front-rear differential pressure is basically calculated as the value of the EGR valve minimum front-rear differential pressure, and is a partial region where the feedback control function is unlikely to be switched, that is, the Dth valve actual closing degree is a predetermined closing degree. It is calculated so as to be smaller than the EGR valve minimum front-rear differential pressure in a partial region closer to β. The predetermined closing degree β is determined in consideration of the control calculation cycle of the EGR valve differential pressure control, the control calculation cycle of the Dth valve fresh air amount control, the control responsiveness of the Dth valve 24 and the EGR valve 32, and the like. Any Dth valve closing degree that can control the EGR valve front-rear differential pressure to the EGR valve minimum front-rear differential pressure during the period until the front-rear differential pressure drops below the Dth valve minimum front-rear differential pressure is acceptable. According to such control, the EGR valve front-rear differential pressure at the time of switching the feedback control function realizes the EGR valve minimum front-rear differential pressure, while the EGR valve front-rear differential pressure at the time when the feedback control function does not switch is The pressure can be reduced more than the differential pressure. Thereby, the fuel consumption can be further improved while ensuring the control response before and after the switching of the feedback control function.

  Next, details of the Dth valve differential pressure control executed in the fresh air amount control of the present embodiment will be described with reference to FIG. In the Dth valve differential pressure control of the present embodiment, first, the minimum closing degree of the Dth valve (hereinafter referred to as “minimum Dth valve closing” for ensuring the target Dth valve front-rear differential pressure based on the operating conditions including the actual fresh air amount. Degree A ”) is calculated. Then, it is operated to the minimum Dth valve closing degree A for which the Dth valve closing degree is calculated by feedforward control.

  FIG. 6 is a control block diagram in which functional blocks for calculating the minimum Dth valve closing degree A are extracted from the control functions provided in the ECU 50. 4 is a functional block that calculates the map shown in FIG. 4, and calculates the target Dth valve front-rear differential pressure in response to the input of the actual EGR valve opening. The calculation unit 502 is a functional block that calculates the effective opening area of the Dth valve 24. The calculation unit 502 receives the actual fresh air amount “gadly”, the Dth pre-valve pressure “pia”, and the Dth pre-valve gas temperature “thia” and is calculated by the arithmetic unit 501 from the Dth pre-valve pressure “pia”. The target intake pressure “pimtrg” calculated by subtracting the target Dth valve front-rear differential pressure is input. The calculation unit 503 calculates the effective opening area “adth” of the Dth valve 24 when the target Dth valve front-rear differential pressure is realized, using the nozzle equation shown in the following equation (1). In the following formula (1), κ represents a specific heat ratio, and R represents a gas constant.

  The effective opening area “adth” of the Dth valve 24 calculated by the calculation unit 502 is input to the calculation unit 503. In the calculation unit 503, the minimum Dth valve closing degree A corresponding to the input effective opening area “adth” of the Dth valve 24 is calculated using a characteristic map that defines the characteristic of the Dth valve closing degree with respect to the effective opening area of the Dth valve. Calculated.

  In the fresh air volume control, environmental correction is performed to reflect the environmental conditions in the target fresh air volume in order to realize the required torque even in the environment of low atmospheric temperature, low water temperature, or low pressure. . Since the actual fresh air amount is a value reflecting the contents of the environmental correction, the above-mentioned minimum Dth valve closing degree A can be calculated as a value corresponding to the environmental condition. Therefore, according to the fresh air amount control of the present embodiment, by controlling the Dth valve closing degree to the minimum Dth valve closing degree A, it becomes possible to perform Dth valve differential pressure control corresponding to the environmental conditions. .

  Next, details of the EGR valve differential pressure control executed in the new air amount control of the present embodiment will be described with reference to FIG. In the EGR valve differential pressure control according to the present embodiment, first, the maximum opening of the EGR valve (hereinafter referred to as “maximum EGR valve opening” for ensuring the target differential pressure before and after the EGR valve based on the operating conditions including the actual EGR gas amount is used. Degree B ”) is calculated. Then, the maximum EGR valve opening degree B calculated by the feedforward control is operated.

  FIG. 7 is a control block diagram in which functional blocks for calculating the maximum EGR valve opening degree B are extracted from the control functions provided in the ECU 50. The calculation unit 511 shown in this figure calculates the target EGR valve front-rear differential pressure in response to the input of the Dth valve actual closing degree. The calculation unit 512 is a functional block that calculates the effective opening area of the EGR valve 32. The calculation unit 512 receives the actual EGR gas amount “gegr”, the EGR valve pre-pressure “pegr”, and the EGR valve pre-gas temperature “thegr” and is calculated from the EGR valve pre-pressure “pegr” by the calculation unit 511. The target intake pressure “pimtrg” calculated by subtracting the target EGR valve front-rear differential pressure is input. The actual EGR gas amount “gegr” is calculated by subtracting the actual fresh air amount from the actual in-cylinder inflow air amount. At this time, the actual in-cylinder inflow air amount can be calculated by a function using the actual intake pressure detected by the intake pressure sensor 62 and the intake manifold gas temperature detected by the temperature sensor 72. The calculation unit 513 calculates the effective opening area “aegr” of the EGR valve 32 when the target EGR valve front-rear differential pressure is realized, using the nozzle equation shown in the following equation (2). In the following equation (2), κ represents a specific heat ratio, and R represents a gas constant.

  The effective opening area “aegr” of the EGR valve 32 calculated by the calculation unit 512 is input to the calculation unit 513. In the calculation unit 513, the maximum EGR valve opening B corresponding to the input effective opening area “aegr” of the EGR valve 32 is calculated using a characteristic map that defines the characteristic of the EGR valve opening with respect to the effective opening area of the EGR valve. Calculated.

  Like the actual fresh air amount described above, the actual EGR gas amount is a value that reflects the contents of the environmental correction, so the maximum EGR valve opening B calculated based on the operating conditions including the actual EGR gas amount is the environment. It can be calculated as a value corresponding to the condition. For this reason, according to the fresh air amount control of the present embodiment, by controlling the EGR valve opening to the maximum EGR valve opening B, it is possible to perform EGR valve differential pressure control corresponding to the environmental conditions. .

[Specific Processing in First Embodiment]
Next, specific processing in the above-described fresh air amount control will be described in detail using a flowchart. FIG. 8 is a flowchart showing the first half of a routine for new air amount control executed by ECU 50 according to the first embodiment of the present invention. FIG. 9 is a flowchart showing the latter half of the routine for fresh air amount control executed by the ECU 50 according to the first embodiment of the present invention.

  In step S1 of the routine shown in FIG. 8, the target fresh air amount is calculated from the engine rotational speed measured from the signal from the rotational speed sensor 52 and the fuel injection amount obtained from the signal from the accelerator opening sensor 70. . In step S2, the actual fresh air amount is detected from the signal of the air flow meter 54. In step S3, the gas pressure before the Dth valve is detected from the signal from the pressure sensor 58. In step S4, the gas pressure before EGR valve is detected from the signal of the pressure sensor 64. The processing in the above steps is processing for obtaining data necessary for processing in the steps described later. Therefore, the order of each step can be changed as appropriate.

  In the next step S5, processing for calculating the target Dth valve front-rear differential pressure is performed. More specifically, in step S5, using the map shown in FIG. 4 that defines the relationship between the actual opening of the EGR valve and the differential pressure across the target Dth valve, the actual EGR valve obtained from the signal of the opening sensor 68 is used. A target Dth valve front-rear differential pressure corresponding to the opening is calculated. In the next step S6, the actual closing degree of the Dth valve obtained from the signal of the opening degree sensor 60 using the map shown in FIG. 5 which defines the relationship between the actual opening degree of the Dth valve and the differential pressure before and after the target EGR valve. The target EGR valve front-rear differential pressure corresponding to is calculated.

  In the next step S7, the minimum Dth valve closing degree A is calculated. More specifically, in step S7, the target Dth valve front-rear differential pressure calculated in step S5, the Dth pre-valve gas pressure calculated in step S3, the actual fresh air amount calculated in step S2, The minimum Dth valve closing degree A is calculated from the gas temperature before the Dth valve obtained from the signal of the temperature sensor 56 using the nozzle equation shown in the above equation (1).

  In the next step S8, the maximum EGR valve opening degree B is calculated. More specifically, in step S8, the actual intake air amount obtained from the intake manifold gas temperature obtained from the signal from the temperature sensor 72, the intake pressure obtained from the intake pressure sensor 62, and the actual fresh air amount calculated in step S2 is calculated. From the EGR gas amount, the target EGR valve front-rear differential pressure calculated in step S6, the EGR valve pre-gas pressure calculated in step S4, and the EGR valve pre-gas temperature obtained from the signal of the temperature sensor 66, The maximum EGR valve opening degree B is calculated using the nozzle equation shown in the above equation (2).

  After the process of step S8 shown in FIG. 8, the process proceeds to step S9 shown in FIG. In step S9, it is determined whether or not the engine has just been started. Immediately after cranking is performed and the engine is started, combustion tends to become unstable. Here, after firing by cranking, whether a period of unstable combustion immediately after engine startup has elapsed, such as whether a predetermined time has elapsed or whether the coolant temperature has reached a predetermined water temperature, etc. It is determined whether or not. As a result, if it is determined that the engine has just started, the EGR valve fresh air, which is safer control among the EGR valve fresh air amount control and the Dth valve fresh air amount control included in the new air amount control, is determined. When it is determined that the amount control should be performed, the process proceeds to step S11 described later.

  On the other hand, if it is determined in step S9 that it is not immediately after the engine is started, the routine proceeds to the next step S10, where it is determined whether or not the fresh air amount is controlled by the EGR valve. More specifically, it is determined whether or not the result of the previous routine calculation is EGR valve fresh air amount control. As a result, when it is determined that the fresh air amount is not controlled by the EGR valve, it is determined that the fresh air amount is controlled by the Dth valve, and the process proceeds to step S14 described later.

  On the other hand, if it is determined in step S10 that the fresh air amount is controlled by the EGR valve, the process proceeds to the next step S11. In step S11, EGR valve fresh air amount control and Dth valve differential pressure control are executed in parallel. In the EGR valve fresh air amount control, the EGR valve opening is determined by feedback control so that the actual fresh air amount detected in step S2 approaches the target fresh air amount calculated in step S1. In the Dth valve differential pressure control, the Dth valve closing degree is set to the minimum Dth valve closing degree A calculated in step S7.

  In the next step S12, it is determined whether or not the actual opening of the EGR valve is larger than the maximum EGR valve opening B calculated in step S8 as a result of executing the EGR valve fresh air amount control. As a result, when the actual opening degree of the EGR valve is equal to or less than the maximum EGR valve opening degree B, it is determined that the EGR valve fresh air amount control should be continuously executed, and this routine is once ended. Then, the routines shown in FIGS. 8 and 9 are executed again from the beginning.

  On the other hand, if it is determined in step S12 that the actual opening degree of the EGR valve is greater than the maximum EGR valve opening degree B, it is determined that the EGR valve front-rear differential pressure is smaller than the EGR valve minimum front-rear differential pressure. Then, the process proceeds to the next step S13, and the feedback control function is switched in the new air amount control. In step S13, specifically, the feedback control function in the new air amount control is switched from the EGR valve new air amount control to the Dth valve new air amount control.

  In the next step S14, the Dth valve fresh air amount control and the EGR valve differential pressure control are executed in parallel. In the Dth valve fresh air amount control, the Dth valve closing degree is determined by feedback control so that the actual fresh air amount approaches the target fresh air amount. In the EGR valve differential pressure control, the EGR valve opening is set to the maximum EGR valve opening B calculated in step S8. In the next step S15, it is determined whether or not the actual closing degree of the Dth valve is smaller than the minimum Dth valve closing degree A calculated in step S7 as a result of executing the Dth valve fresh air amount control. As a result, when the actual opening degree of the Dth valve is equal to or greater than the minimum Dth valve closing degree A, it is determined that the Dth valve fresh air amount control should be continuously executed, and this routine is once ended. Then, the routines shown in FIGS. 8 and 9 are executed again from the beginning.

  On the other hand, when it is determined in step S15 that the actual closing degree of the Dth valve is smaller than the minimum Dth valve closing degree A, it is determined that the Dth valve front-rear differential pressure is smaller than the Dth valve minimum front-rear differential pressure. Then, the process proceeds to the next step S16, and the feedback control function is switched in the new air amount control. In step S16, specifically, the feedback control function in the new air amount control is switched from the Dth valve new air amount control to the EGR valve new air amount control. When the process of step S16 is executed, this routine is ended, and the routines shown in FIGS. 8 and 9 are executed again.

  By performing the new air amount control according to the routine described above, the differential pressure across the Dth valve 24 and the EGR valve 32 when switching the feedback control function can be controlled to the minimum differential pressure. As a result, it is possible to effectively suppress deterioration of fuel consumption while ensuring control response and convergence in the fresh air amount control.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the first embodiment described above, the target fresh air amount is calculated as the control target value for the fresh air amount control, and the Dth valve 24 or the EGR valve 32 is controlled so that the actual fresh air amount approaches the target fresh air amount. Yes. However, the control target value of the fresh air amount control is not limited to the target fresh air amount. That is, as described above, the actual in-cylinder inflow air amount can be calculated by a function using the actual intake pressure detected by the intake pressure sensor 62 and the intake manifold gas temperature detected by the temperature sensor 72. For this reason, the EGR gas amount sucked into the cylinder can be calculated by a function of subtracting the fresh air amount sucked into the cylinder from the actual in-cylinder inflow air quantity. Also, the EGR rate can be calculated by a function using the actual in-cylinder inflow air amount and the fresh air amount. Further, by grasping the oxygen concentration of fresh air and the oxygen concentration of EGR gas by a known means, the intake O2 concentration, which is the oxygen concentration of the actual in-cylinder inflow air, is also calculated by a function using the fresh air amount. Can do. Further, by grasping the fresh air temperature and the EGR gas temperature by known means, the intake manifold gas temperature can also be calculated by a function using the fresh air amount. Thus, since the EGR rate, EGR gas amount, intake O2 concentration, and intake manifold gas temperature are state quantities that have a correlation with the new air quantity, even if the target values of these state quantities are used for the new air quantity control. Good. The same applies to other embodiments described later.

  In the first embodiment described above, the Dth pre-valve gas pressure, the EGR pre-valve gas pressure, the intake manifold gas temperature, the Dth pre-valve gas temperature, the EGR pre-gas temperature, and the intake pressure are directly calculated from the sensor signals. However, these values may be estimated using a known method.

  In the first embodiment described above, the target Dth valve front-rear differential pressure is calculated according to the relationship shown in FIG. However, the calculation method of the target Dth valve front-rear differential pressure is not limited to this, and other maps may be used as long as the Dth valve minimum front-rear differential pressure can be ensured at the time of switching, and depending on the actual opening of the EGR valve It is good also as fixing with the value of Dth valve minimum back-and-forth differential pressure without changing. The same applies to the calculation of the target EGR valve front-rear differential pressure.

  Further, in the above-described new air amount control of the first embodiment, Dth valve new air amount control and Dth valve differential pressure control are executed as control using the Dth valve 24, and EGR valve new control is performed as control using the EGR valve 32. The air volume control and the EGR valve differential pressure control are executed. However, in the new air amount control of the present embodiment, either one of the control using the Dth valve 24 and the control using the EGR valve 32 may be replaced with the control of another embodiment described later.

  In the first embodiment described above, the Dth valve 24 corresponds to the “throttle valve” of the first invention, and the Dth valve fresh air amount control is changed to the “throttle valve fresh air amount control” of the first invention. EGR valve fresh air amount control corresponds to “EGR valve fresh air amount control” of the first invention, and Dth valve differential pressure control corresponds to “throttle valve differential pressure control” of the first invention. The EGR valve differential pressure control corresponds to the "EGR valve differential pressure control" of the first invention, the Dth valve front-rear differential pressure corresponds to the "first differential pressure" of the first invention, and the target Dth valve front-rear. The differential pressure corresponds to the “throttle valve target differential pressure” of the first invention, the EGR valve front-rear differential pressure corresponds to the “second differential pressure” of the first invention, and the target EGR valve front-back differential pressure This corresponds to the “EGR valve target differential pressure” of the first invention. Further, in the first embodiment described above, the “switching control means” in the first aspect of the present invention is realized by the ECU 50 executing the processing of step S12 and step S13 or step S15 and step S16. By executing the processing in step S11 or step S14, the “differential pressure control means” in the first invention is realized.

  In the first embodiment described above, the minimum Dth valve closing degree A corresponds to the “closing degree for throttle valve differential pressure control” of the second aspect of the invention. Further, in the first embodiment described above, the ECU 50 executes the process of step S7 to realize the “closed degree calculation means” in the second invention, and the ECU 50 executes the processes of step S12 and step S13. Thus, the “switching control means” in the second invention is realized, and the “differential pressure control means” in the second invention is realized by the ECU 50 executing the process of step S11.

  In the first embodiment described above, the minimum Dth valve closing degree A corresponds to the “closing degree for throttle valve differential pressure control” of the third aspect of the invention. Further, in the first embodiment described above, the “closed degree calculating means” in the third aspect of the present invention is realized by the ECU 50 executing the process of step S7.

  Further, in the first embodiment described above, the “throttle valve target differential pressure calculating means” in the sixth aspect of the present invention is realized by the ECU 50 executing the process of step S5.

  In the first embodiment described above, the maximum EGR valve opening B corresponds to the “EGR valve differential pressure control opening” of the seventh aspect of the invention. In the first embodiment described above, the ECU 50 executes the process of step S8 to realize the “opening degree calculation means” in the seventh aspect of the invention, and the ECU 50 executes the processes of step S15 and step S16. Thus, the “switching control means” in the seventh invention is realized, and the “differential pressure control means” in the seventh invention is realized by the ECU 50 executing the process of step S14.

  In the first embodiment described above, the maximum EGR valve opening B corresponds to the “EGR valve differential pressure control opening” in the eighth aspect of the invention. Further, in the first embodiment described above, the “opening degree calculation means” in the eighth aspect of the present invention is realized by the ECU 50 executing the process of step S8.

  Further, in the first embodiment described above, the “EGR valve target differential pressure calculating means” in the eleventh aspect of the present invention is realized by the ECU 50 executing the process of step S6.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. The second embodiment according to the present invention can be realized by causing the ECU 50 to execute a routine shown in FIG. 12 described later and the above-described FIG. 9 using the hardware configuration shown in FIG.

[Configuration of Embodiment 2]
FIG. 10 is a diagram showing a configuration of an engine system to which the control device of the second embodiment of the present invention is applied. 10 includes a pressure sensor 58 for detecting the gas pressure before the Dth valve, a pressure sensor 64 for detecting the gas pressure before the EGR valve, a temperature sensor 66 for detecting the gas temperature before the EGR valve, 1 except that the temperature sensor 72 for detecting the intake manifold gas temperature is not provided.

[Features of Embodiment 2]
In the control device of the first embodiment described above, the minimum Dth valve closing degree A and the maximum EGR valve opening degree B are calculated using the state quantities before and after the Dth valve 24 and the EGR valve 32. For this reason, in the control apparatus of Embodiment 1, it is necessary to use a sensor for accurately grasping the state quantities before and after the Dth valve 24 and the EGR valve 32. The control device according to the second embodiment has a minimum Dth valve closing degree A and an EGR valve minimum front-rear difference for realizing the Dth valve minimum front-rear differential pressure without using the state quantities before and after the Dth valve 24 and the EGR valve 32. The method is characterized in that the maximum EGR valve opening degree B for realizing the pressure is calculated.

  As a method for calculating the minimum Dth valve closing degree A, for example, it is conceivable to use a map that defines the minimum Dth valve closing degree A for realizing the Dth valve minimum front-rear differential pressure using the rotation speed and the injection amount as arguments. . However, such maps do not reflect changes in environmental conditions. For this reason, for example, when the target fresh air amount or the target EGR rate during EGR valve fresh air volume control increases due to environmental conditions such as low water temperature and low pressure, the Dth valve front-rear differential pressure is higher than the Dth valve minimum front-rear differential pressure. It gets bigger. In this case, the pumping loss increases, resulting in deterioration of fuel consumption.

  Therefore, in the control device according to the second embodiment of the present invention, changes in environmental conditions are reflected in the minimum Dth valve closing degree A by the following control logic. FIG. 11 is a control block diagram in which functional blocks for calculating the minimum Dth valve closing degree A are extracted from the control functions provided in the ECU 50 according to the second embodiment of the present invention. The calculation unit 521 shown in this figure is a functional block for calculating the base value of the minimum Dth valve closing degree A using a map. The map used in the calculation of the calculation unit 521 is associated with the base value of the minimum Dth valve closing degree A for realizing the Dth valve minimum front-rear differential pressure with the rotation speed and the injection amount as arguments. The calculation unit 521 uses this map to calculate the base value of the minimum Dth valve closing degree A corresponding to the input rotational speed “ne” and the injection amount “q”.

  The calculation unit 522 is a functional block for calculating a closing degree correction value for reflecting the influence of the atmospheric pressure change on the minimum Dth valve closing degree A. The map used in the calculation of the calculation unit 522 is associated with a closing degree correction value of the minimum Dth valve closing degree A due to a change in atmospheric pressure using the rotation speed, the injection amount, and the atmospheric pressure as arguments. The computing unit 522 calculates a closing degree correction value corresponding to the input rotational speed “ne”, injection amount “q”, and atmospheric pressure “pa” using the map.

  The calculation unit 523 is a functional block for calculating a correction coefficient for reflecting the influence of the change in the engine coolant temperature on the minimum Dth valve closing degree A. The map used in the calculation of the calculation unit 523 is associated with the correction coefficient of the closing degree correction value using the water temperature as an argument. The calculation unit 523 calculates a correction coefficient corresponding to the input water temperature “thw” using the map. The calculation unit 524 is a functional block for calculating a correction coefficient for reflecting the influence of the change in the atmospheric temperature on the minimum Dth valve closing degree A. The map used in the calculation of the calculation unit 524 is associated with the correction coefficient of the closing degree correction value using the atmospheric temperature as an argument. The calculation unit 524 calculates a correction coefficient corresponding to the input atmospheric temperature “tha” using the map. The closing degree correction value calculated by the calculation unit 522 is added to the base value of the minimum Dth valve closing degree A after the correction coefficient calculated by the calculation unit 523 and the correction coefficient calculated by the calculation unit 524 are sequentially multiplied. Is done. As a result, the minimum Dth valve closing degree A reflecting the environmental conditions regarding the water temperature, the atmospheric temperature, and the atmospheric pressure is calculated. Therefore, the differential pressure before and after the Dth valve is reduced to the minimum value in the low water temperature environment, the low atmospheric temperature environment, and the low pressure environment. The pressure difference can be approached.

  In the control device according to the second embodiment of the present invention, the change in environmental conditions is reflected in the maximum EGR valve opening B by the following control logic. FIG. 12 is a control block diagram in which functional blocks for calculating the maximum EGR valve opening degree B are extracted from the control functions provided in the ECU 50 according to the second embodiment of the present invention. The arithmetic unit 531 shown in this figure is a functional block for calculating the base value of the maximum EGR valve opening degree B using a map. In the calculation unit 531, the base value of the maximum EGR valve opening degree B for realizing the EGR valve minimum front-rear differential pressure is associated with the rotation speed and the injection amount as arguments. The calculation unit 531 uses this map to calculate the base value of the maximum EGR valve opening degree B corresponding to the input rotational speed “ne” and the injection amount “q”.

  The calculation unit 532 is a functional block for calculating an opening correction value for reflecting the influence of a change in atmospheric pressure on the maximum EGR valve opening B. The map used in the calculation of the calculation unit 532 is associated with an opening correction value of the maximum EGR valve opening B due to a change in atmospheric pressure using the rotation speed, the injection amount, and the atmospheric pressure as arguments. The computing unit 532 calculates an opening correction value corresponding to the input rotational speed “ne”, injection amount “q”, and atmospheric pressure “pa” using the map.

  The calculation unit 533 is a functional block for calculating a correction coefficient for reflecting the influence of the change in the water temperature on the maximum EGR valve opening degree B. The map used in the calculation of the calculation unit 533 is associated with a correction coefficient of the opening correction value using the water temperature as an argument. The computing unit 533 calculates a correction coefficient corresponding to the input water temperature “thw” using the map. The computing unit 534 is a functional block for calculating a correction coefficient for reflecting the influence of the change in the atmospheric temperature on the maximum EGR valve opening degree B. The map used in the calculation of the calculation unit 534 is associated with a correction coefficient of the opening correction value using the atmospheric temperature as an argument. The calculation unit 534 calculates a correction coefficient corresponding to the input atmospheric temperature “tha” using the map. The opening correction value calculated by the calculation unit 532 is added to the base value of the maximum EGR valve opening B after the correction coefficient calculated by the calculation unit 533 and the correction coefficient calculated by the calculation unit 534 are sequentially multiplied. Is done. As a result, the maximum EGR valve opening degree B reflecting the environmental conditions related to the water temperature, the atmospheric temperature, and the atmospheric pressure is calculated. Therefore, the differential pressure before and after the EGR valve is minimized even in the low water temperature environment, the low atmospheric temperature environment, and the low pressure environment. The pressure difference can be approached.

[Specific Processing of Embodiment 2]
Next, specific processing in the above-described fresh air amount control will be described in detail using a flowchart. FIG. 13 is a flowchart showing the first half of a routine for new air amount control executed by the ECU 50 according to the second embodiment of the present invention.

  In step S21 of the routine shown in FIG. 13, the target fresh air amount is calculated from the engine rotational speed measured from the signal from the rotational speed sensor 52 and the fuel injection amount obtained from the signal from the accelerator opening sensor 70. . In step S22, the actual fresh air amount is detected from the signal of the air flow meter 54. The processing in the above steps is processing for obtaining data necessary for processing in the steps described later. Therefore, the order of each step can be changed as appropriate.

  In the next step S23, the minimum Dth valve closing degree A is calculated. More specifically, in step S23, the above-described calculation of the control logic shown in FIG. 11 is executed. In the next step S24, the maximum EGR valve opening B is calculated. More specifically, in step S24, the above-described calculation of the control logic shown in FIG. 12 is executed. After the process of step S24 shown in FIG. 13, the process proceeds to the latter half of the routine for controlling the fresh air amount shown in FIG. The routine shown in FIG. 9 is the same as the latter half of the routine for controlling the amount of fresh air in the first embodiment, and a description thereof will be omitted.

  By performing the new air amount control according to the routine described above, the differential pressure before and after the Dth valve 24 and the EGR valve 32 at the time of switching the feedback control function is controlled to the minimum differential pressure even in a low temperature environment or a low pressure environment. Can do. As a result, it is possible to effectively suppress deterioration of fuel consumption while ensuring control response and convergence in the fresh air amount control.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the second embodiment described above, the minimum Dth valve closing degree A subjected to environmental correction is calculated according to the control logic shown in FIG. However, the calculation method of the minimum Dth valve closing degree A is not limited to this, and may be a control logic that performs any one of the low water temperature correction, the low and high temperature correction, and the low pressure correction as the environmental correction, or to cope with other environmental conditions. It may be configured to include this correction. The same applies to the calculation of the maximum EGR valve opening degree B.

  Further, in the control device of the second embodiment described above, the minimum Dth valve closing degree A for realizing the Dth valve minimum front-rear differential pressure is calculated, but the minimum for realizing the target Dth valve front-rear differential pressure is calculated. The Dth valve closing degree A may be calculated. As a control logic for realizing such a calculation function, for example, in the control logic shown in FIG. 11, a functional block for calculating the target Dth valve front-rear differential pressure in response to the input of the actual EGR valve opening (that is, FIG. 6). The calculation unit 501) shown in FIG. The calculated target Dth valve front-rear differential pressure is input to the calculation unit 521. In the calculation unit 521, in addition to the rotation speed and the injection amount, the target Dth valve front-rear differential pressure is used as an argument to determine the minimum Dth valve closing degree. A map associated with the base value of A is used. According to such a control logic, it is possible to calculate the minimum Dth valve closing degree A for realizing the target Dth valve front-rear differential pressure.

  Similarly, the maximum EGR valve opening degree B for realizing the target EGR valve front-rear differential pressure may be calculated for the calculation of the maximum EGR valve opening degree B. As a control logic for realizing such a calculation function, for example, in the control logic shown in FIG. 12, a functional block for calculating the target EGR valve front-rear differential pressure in response to the input of the Dth valve actual closing degree (that is, FIG. 7). The calculation unit 511) shown in FIG. The calculated target EGR valve front-rear differential pressure is input to the calculation unit 531, and the calculation unit 531 uses the target EGR valve front-rear differential pressure as an argument in addition to the rotation speed and the injection amount, and the maximum EGR valve opening degree. A map associated with the base value of B is used. According to such a control logic, it is possible to calculate the maximum EGR valve opening degree B for realizing the target EGR valve front-rear differential pressure.

  In addition, in the above-described new air amount control of the second embodiment, Dth valve new air amount control and Dth valve differential pressure control are executed as control using the Dth valve 24, and EGR valve new control is performed as control using the EGR valve 32. The air volume control and the EGR valve differential pressure control are executed. However, in the new air amount control of the present embodiment, one of the control using the Dth valve 24 and the control using the EGR valve 32 is the control of the first embodiment described above or the control of the embodiment described later. May be substituted.

  In the second embodiment described above, the Dth valve 24 corresponds to the “throttle valve” of the first invention, and the Dth valve fresh air amount control is changed to the “throttle valve fresh air amount control” of the first invention. EGR valve fresh air amount control corresponds to “EGR valve fresh air amount control” of the first invention, and Dth valve differential pressure control corresponds to “throttle valve differential pressure control” of the first invention. The EGR valve differential pressure control corresponds to the "EGR valve differential pressure control" of the first invention, the Dth valve front-rear differential pressure corresponds to the "first differential pressure" of the first invention, and the target Dth valve front-rear. The differential pressure corresponds to the “throttle valve target differential pressure” of the first invention, the EGR valve front-rear differential pressure corresponds to the “second differential pressure” of the first invention, and the target EGR valve front-back differential pressure This corresponds to the “EGR valve target differential pressure” of the first invention. Further, in the second embodiment described above, the “switching control means” in the first aspect of the present invention is realized by the ECU 50 executing the processing of step S12 and step S13 or step S15 and step S16. By executing the processing in step S11 or step S14, the “differential pressure control means” in the first invention is realized.

  In the second embodiment described above, the minimum Dth valve closing degree A corresponds to the “closing degree for throttle valve differential pressure control” of the second aspect of the invention. In the first embodiment described above, the ECU 50 executes the process of step S23 to realize the “closed degree calculation means” in the second invention, and the ECU 50 executes the processes of step S12 and step S13. Thus, the “switching control means” in the second invention is realized, and the “differential pressure control means” in the second invention is realized by the ECU 50 executing the process of step S11.

  In the second embodiment described above, the minimum Dth valve closing degree A corresponds to the “closing degree for throttle valve differential pressure control” of the fourth invention. In the first embodiment described above, the “closed degree calculating means” according to the fourth aspect of the present invention is implemented when the ECU 50 executes the process of step S23.

  In the second embodiment described above, the maximum EGR valve opening B corresponds to the “EGR valve differential pressure control opening” of the seventh aspect of the invention. In the second embodiment described above, the ECU 50 executes the process of step S8 to realize the “opening degree calculation means” in the seventh aspect of the invention, and the ECU 50 executes the processes of step S15 and step S16. Thus, the “switching control means” in the seventh invention is realized, and the “differential pressure control means” in the seventh invention is realized by the ECU 50 executing the process of step S14.

  In the second embodiment described above, the maximum EGR valve opening B corresponds to the “EGR valve differential pressure control opening” in the eighth aspect of the invention. In the first embodiment described above, the “opening degree calculation means” in the eighth aspect of the present invention is realized by the ECU 50 executing the process of step S24.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. The third embodiment according to the present invention can be realized by causing the ECU 50 to execute routines shown in FIGS. 15 and 16 to be described later, using the hardware configuration shown in FIG.

[Configuration of Embodiment 3]
FIG. 14 is a diagram showing a configuration of an engine system to which the control device of the third embodiment of the present invention is applied. The control device shown in FIG. 14 is the same as the control device shown in FIG. 1 except that the temperature sensor 66 for detecting the gas temperature before the EGR valve and the temperature sensor 72 for detecting the intake manifold gas temperature are not provided. It has the same configuration.

[Features of Embodiment 3]
In the control device according to the third embodiment, the actual values of the Dth valve front-rear differential pressure and the EGR valve front-rear differential pressure are detected based on the state quantities of the Dth valve 24 and the EGR valve 32 before and after the valve, and the detected Dth valve front-rear pressure is detected. The new air amount control is executed using the differential pressure and the differential pressure before and after the EGR valve. More specifically, in the control device of the third embodiment, when the actual value of the Dth valve front-rear differential pressure falls below the Dth valve minimum front-rear differential pressure during execution of the Dth valve fresh air amount control, the feedback control function is applied. Switching from the Dth valve fresh air amount control to the EGR valve fresh air amount control is performed. In the control device of the third embodiment, when the actual value of the EGR valve front-rear differential pressure is lower than the EGR valve minimum front-rear differential pressure during execution of the EGR valve fresh air amount control, the feedback control function is applied to the EGR valve. Switching from the new valve air amount control to the Dth valve new air amount control is performed. According to such feedback control of the fresh air amount, it is possible to accurately determine the switching timing of the feedback control function based on the detected Dth valve front-rear differential pressure and EGR valve front-rear differential pressure.

  Further, in the control device of the third embodiment, in the Dth valve differential pressure control, the Dth valve closing degree is determined by feedback control so that the actual value of the Dth valve differential pressure before and after approaches the target Dth valve differential pressure. Is done. When the Dth valve closing degree is determined by feedback control, it is executed at a cycle slower than the EGR valve fresh air amount control so as not to interfere with the EGR valve fresh air amount control executed as the new air amount control. Is done.

  In the control device of the third embodiment, in the EGR valve differential pressure control, the EGR valve opening degree is determined by feedback control so that the actual value of the differential pressure before and after the EGR valve approaches the target differential pressure before and after the EGR valve. Is done. When the EGR valve opening is determined by feedback control, it is executed at a cycle slower than the Dth valve fresh air amount control so as not to interfere with the Dth valve fresh air amount control being executed as the new air amount control. Is done.

  According to such differential pressure control, the Dth valve front-rear differential pressure and the EGR valve front-rear differential pressure can be reliably brought close to the target Dth valve front-rear differential pressure and the target EGR valve front-rear differential pressure. It is possible to suppress the deterioration of the control responsiveness and minimize the deterioration of the fuel consumption.

[Specific Processing of Embodiment 3]
Next, specific processing in the above-described fresh air amount control will be described in detail using a flowchart. FIG. 15 is a flowchart showing the first half of a routine for new air amount control executed by the ECU 50 according to the third embodiment of the present invention. FIG. 16 is a flowchart showing the latter half of the routine for fresh air amount control executed by the ECU 50 according to the third embodiment of the present invention.

  In steps S31 to S34 of the routine shown in FIG. 15, the same processes as those in steps S1 to S4 shown in FIG. 8 are executed. In step S35, the intake pressure is detected from the signal of the intake pressure sensor 62. The processing in the above steps is processing for obtaining data necessary for processing in the steps described later. Therefore, the order of each step can be changed as appropriate.

  In the next step S36, the differential pressure before and after the EGR valve is calculated from the intake pressure detected in the step S35 and the gas pressure before the EGR valve detected in the step S34. In the next step S37, the differential pressure before and after the Dth valve is calculated from the intake pressure detected in step S35 and the gas pressure before the Dth valve detected in step S33.

  In the next step S38, processing for calculating the target Dth valve front-rear differential pressure is performed. Here, specifically, the same process as the process of step S5 shown in FIG. 8 is executed. In the next step S39, a process for calculating a target EGR valve front-rear differential pressure is performed. Here, specifically, the same process as the process of step S6 shown in FIG. 8 is executed.

  After the process of step S39 shown in FIG. 15, the process proceeds to step S40 shown in FIG. In step S40, it is determined whether or not the engine has just been started. Here, specifically, the same process as the process of step S9 shown in FIG. 9 is executed. As a result, if it is determined that the engine has just been started, the process proceeds to step S42 described later.

  On the other hand, if it is determined in step S40 that it is not immediately after the engine is started, the process proceeds to the next step S41, where it is determined whether or not the fresh air amount is controlled by the EGR valve. More specifically, the same process as the process of step S10 shown in FIG. 9 is executed. As a result, if it is determined that the fresh air amount is not controlled by the EGR valve, the process proceeds to step S45 described later.

  On the other hand, if it is determined in step S41 that the fresh air amount is controlled by the EGR valve, the process proceeds to the next step S42. In step S42, EGR valve fresh air amount control and Dth valve differential pressure control are executed in parallel. In EGR valve fresh air amount control, the EGR valve opening is determined by feedback control so that the actual fresh air amount detected in step S32 approaches the target fresh air amount calculated in step S31. Further, in the Dth valve differential pressure control, the Dth valve closing degree is determined by feedback control so that the Dth valve front-rear differential pressure calculated in step S37 approaches the target Dth valve front-rear differential pressure calculated in step S38. It is determined.

  In the next step S43, whether or not the EGR valve front-rear differential pressure is lower than the target EGR valve front-rear differential pressure calculated in step S39 as a result of executing the EGR valve fresh air amount control as the new air amount feedback control. Is determined. As a result, if the EGR valve front-rear differential pressure does not fall below the target EGR valve front-rear differential pressure, it is determined that the EGR valve fresh air amount control should be continued, and this routine is once terminated. Then, the routines shown in FIGS. 15 and 16 are executed again from the beginning.

  On the other hand, if the EGR valve front-rear differential pressure is lower than the target EGR valve front-rear differential pressure in step S43, the process proceeds to the next step S44, and the feedback control function in the new air amount control is performed by the EGR valve fresh air amount. The control is switched to Dth valve fresh air amount control.

  In the next step S45, Dth valve fresh air amount control and EGR valve differential pressure control are executed in parallel. In the Dth valve fresh air amount control, the Dth valve closing degree is determined by feedback control so that the actual fresh air amount detected in step S32 approaches the target fresh air amount calculated in step S31. Further, in the EGR valve differential pressure control, the EGR valve opening degree is controlled by feedback control so that the EGR valve front-rear differential pressure calculated in step S36 approaches the target EGR valve front-rear differential pressure calculated in step S39. It is determined.

  In the next step S46, as a result of executing the Dth valve fresh air amount control as the new air amount feedback control, whether or not the Dth valve front-rear differential pressure is lower than the target Dth valve front-rear differential pressure calculated in step S38. Is determined. As a result, when the Dth valve front-rear differential pressure does not fall below the target Dth valve front-rear differential pressure, it is determined that the Dth valve fresh air amount control should be continued, and this routine is once terminated. Then, the routines shown in FIGS. 15 and 16 are executed again from the beginning.

  On the other hand, if the Dth valve front-rear differential pressure is lower than the target Dth valve front-rear differential pressure in step S46, the process proceeds to the next step S47, and the feedback control function in the new air amount control performs the Dth valve new air amount. The control is switched to EGR valve fresh air amount control.

  By performing the new air amount control according to the routine described above, the differential pressure across the Dth valve 24 and the EGR valve 32 when switching the feedback control function can be controlled to the minimum differential pressure. As a result, it is possible to effectively suppress deterioration of fuel consumption while ensuring control response and convergence in the fresh air amount control.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above-described third embodiment, the Dth valve front-rear differential pressure is calculated using the Dth valve pre-gas pressure detected by the pressure sensor 58 and the intake pressure detected by the intake pressure sensor 62. However, the configuration for calculating the differential pressure before and after the Dth valve is not limited thereto, and instead of these sensors, a gas differential pressure sensor before and after the Dth valve that detects the gas differential pressure before and after the Dth valve may be provided. According to such a configuration, it is possible to directly detect the differential pressure across the Dth valve using the gas differential pressure sensor across the Dth valve. Similarly, for the EGR valve front-rear differential pressure, a pressure sensor 64 for detecting the gas pressure before the EGR valve and an EGR valve front-rear gas differential pressure sensor for detecting the gas differential pressure before and after the EGR valve are provided instead of the intake pressure sensor 62. It is good as well. According to such a configuration, it is possible to directly detect the EGR valve front-rear differential pressure using the EGR valve front-rear gas differential pressure sensor.

  In Embodiment 3 described above, the Dth valve pre-gas pressure and the intake pressure are directly calculated from the sensor signals, but these values may be estimated using a known method.

  In the third embodiment described above, the target Dth valve front-rear differential pressure is calculated according to the relationship shown in FIG. However, the calculation method of the target Dth valve front-rear differential pressure is not limited to this, and other maps may be used as long as the Dth valve minimum front-rear differential pressure can be secured at the time of switching, and also depends on the actual EGR valve opening. The Dth valve may be fixed at the minimum differential pressure before and after. The same applies to the calculation of the target EGR valve front-rear differential pressure.

  Further, in the above-described new air amount control of the third embodiment, Dth valve new air amount control and Dth valve differential pressure control are executed as control using the Dth valve 24, and EGR valve new control is executed as control using the EGR valve 32. The air volume control and the EGR valve differential pressure control are executed. However, in the new air amount control of the present embodiment, either the control using the Dth valve 24 or the control using the EGR valve 32 is replaced with the control of the first embodiment or the second embodiment described above. Also good.

  In the third embodiment described above, the Dth valve 24 corresponds to the “throttle valve” of the first invention, and the Dth valve fresh air amount control is changed to the “throttle valve fresh air amount control” of the first invention. EGR valve fresh air amount control corresponds to “EGR valve fresh air amount control” of the first invention, and Dth valve differential pressure control corresponds to “throttle valve differential pressure control” of the first invention. The EGR valve differential pressure control corresponds to the "EGR valve differential pressure control" of the first invention, the Dth valve front-rear differential pressure corresponds to the "first differential pressure" of the first invention, and the target Dth valve front-rear. The differential pressure corresponds to the “throttle valve target differential pressure” of the first invention, the EGR valve front-rear differential pressure corresponds to the “second differential pressure” of the first invention, and the target EGR valve front-back differential pressure This corresponds to the “EGR valve target differential pressure” of the first invention. Further, in the third embodiment described above, the “switching control means” according to the first aspect of the present invention is realized when the ECU 50 executes the processes of steps S43 and S44 or steps S46 and S47. By executing the processing of step S42 or step S45, the “differential pressure control means” in the first aspect of the invention is realized.

  In the third embodiment described above, the “differential pressure control means” according to the fifth aspect of the present invention is implemented when the ECU 50 executes the process of step S42.

  In the third embodiment described above, the “throttle valve target differential pressure calculating means” according to the sixth aspect of the present invention is realized by the ECU 50 executing the process of step S38.

  In the third embodiment described above, the “differential pressure control means” according to the tenth aspect of the present invention is implemented when the ECU 50 executes the process of step S45.

  Further, in the third embodiment described above, the “EGR valve target differential pressure calculating means” in the eleventh aspect of the present invention is realized by the ECU 50 executing the process of step S38.

2 Engine body 4 Intake manifold 6 Exhaust manifold 8 Injector 10 Intake passage 12 Exhaust passage 14 Compressor 16 Turbine 18 Variable nozzle 20 Air cleaner 22 Intercooler 24 Dth valve 26 Catalytic device 30 Passage 32 EGR valve 34 EGR cooler 36 Bypass passage 38 Bypass valve 50 ECU (Electronic Control Unit)
52 Rotational Speed Sensor 54 Air Flow Meter 56 Temperature Sensor 58 Pressure Sensor 60 Opening Sensor 62 Intake Pressure Sensor 64 Pressure Sensor 66 Temperature Sensor 68 Opening Sensor 70 Acceleration Opening Sensor 72 Temperature Sensor

[Features of Embodiment 3]
In the control device according to the third embodiment, the actual values of the Dth valve front-rear differential pressure and the EGR valve front-rear differential pressure are detected based on the state quantities of the Dth valve 24 and the EGR valve 32 before and after the valve, and the detected Dth valve front-rear pressure is detected. The new air amount control is executed using the differential pressure and the differential pressure before and after the EGR valve. More specifically, in the control device of the third embodiment, when the actual value of the Dth valve front-rear differential pressure falls below the Dth valve minimum front-rear differential pressure during execution of the Dth valve fresh air amount control, the feedback control function is applied. Switching from the Dth valve fresh air amount control to the EGR valve fresh air amount control is performed. In the control device of the third embodiment, when the actual value of the EGR valve front-rear differential pressure is lower than the EGR valve minimum front-rear differential pressure during execution of the EGR valve fresh air amount control, the feedback control function is applied to the EGR valve. Switching from the new valve air amount control to the Dth valve new air amount control is performed. According to such feedback control of the fresh air amount , the switching timing of the feedback control function can be accurately determined based on the detected actual values of the differential pressure before and after the Dth valve and the differential pressure before and after the EGR valve.

Claims (11)

A throttle valve disposed in the intake passage, an EGR passage for recirculating exhaust gas downstream of the throttle valve in the intake passage, and an EGR valve disposed in the EGR passage, Throttle valve fresh air amount control for determining the degree of closing of the throttle valve by feedback control so that the state amount correlated with the fresh air amount approaches the target value, and the state amount correlated with the fresh air amount or the fresh air amount In an internal combustion engine control device configured to execute EGR valve fresh air amount control that determines the opening degree of the EGR valve by feedback control so as to approach a target value,
During execution of the EGR valve fresh air amount control, a first differential pressure, which is a difference between a gas pressure upstream of the throttle valve and a gas pressure downstream of the throttle valve in the intake passage, becomes a throttle valve target differential pressure. During the execution of the throttle valve differential pressure control to be controlled and the throttle valve fresh air amount control, a second differential pressure that is a difference between the gas pressure on the upstream side of the EGR valve and the gas pressure on the downstream side in the EGR passage is Differential pressure control means for performing EGR valve differential pressure control for controlling the EGR valve to achieve a target differential pressure;
When the first differential pressure falls below the throttle valve target differential pressure during execution of the throttle valve fresh air amount control, switching to the EGR valve fresh air amount control is performed, and during execution of the EGR valve fresh air amount control, Switching control means for switching to the throttle valve fresh air amount control when the second differential pressure is lower than the EGR valve target differential pressure;
A control device for an internal combustion engine, comprising: The differential pressure control means comprises a closing degree calculating means for calculating a closing degree for throttle valve differential pressure control, which is a closing degree of the throttle valve for the first differential pressure to become the throttle valve target differential pressure, The throttle valve differential pressure control is configured to control the throttle valve closing degree to the throttle valve differential pressure control closing degree,
The switching control means switches to the EGR valve fresh air amount control when the closing degree of the throttle valve is lower than the throttle valve differential pressure control closing degree during execution of the throttle valve fresh air amount control. The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is configured.   The closing degree calculating means is configured to calculate the closing degree for the throttle valve differential pressure control using an actual fresh air amount of the internal combustion engine and a state quantity of gas before and after the throttle valve. The control apparatus for an internal combustion engine according to claim 2, wherein the control apparatus is an internal combustion engine.   The closing degree calculating means is configured to calculate the closing degree for controlling the throttle valve differential pressure based on an operating condition of the internal combustion engine and an environmental condition including a cooling water temperature or an atmospheric pressure or an atmospheric temperature. The control apparatus for an internal combustion engine according to claim 2.   The differential pressure control means obtains the actual value of the first differential pressure, and in the throttle valve differential pressure control, the throttle valve closing degree is determined by feedback control so that the actual value approaches the throttle valve target differential pressure. 2. The control device for an internal combustion engine according to claim 1, wherein the control device is configured to determine.   The control of the internal combustion engine according to any one of claims 2 to 5, further comprising a throttle valve target differential pressure calculating means for calculating the throttle valve target differential pressure in accordance with an opening of the EGR valve. apparatus. The differential pressure control means includes an opening degree calculation means for calculating an opening degree for EGR valve differential pressure control, which is an opening degree of the EGR valve for the second differential pressure to become the EGR valve target differential pressure, The EGR valve differential pressure control is configured to control the opening of the EGR valve to the EGR valve differential pressure control opening,
The switching control means switches to the throttle valve fresh air amount control when the opening degree of the EGR valve becomes larger than the opening degree for EGR valve differential pressure control during execution of the EGR valve fresh air amount control. The control device for an internal combustion engine according to any one of claims 1 to 6, wherein the control device is configured.   The opening degree calculation means is configured to calculate the opening degree for EGR valve differential pressure control using an actual EGR gas amount of the internal combustion engine and a gas state quantity before and after the EGR valve. 8. The control apparatus for an internal combustion engine according to claim 7, wherein the control apparatus is an internal combustion engine.   The opening calculation means is configured to calculate the EGR valve differential pressure control opening based on operating conditions of the internal combustion engine and environmental conditions including cooling water temperature, atmospheric pressure, or atmospheric temperature. The control apparatus for an internal combustion engine according to claim 7.   The differential pressure control means obtains an actual value of the second differential pressure, and controls the opening degree of the EGR valve by feedback control so that the actual value approaches the EGR valve target differential pressure in the EGR valve differential pressure control. The control device for an internal combustion engine according to any one of claims 1 to 6, wherein the control device is configured to determine.   11. The control of an internal combustion engine according to claim 7, further comprising an EGR valve target differential pressure calculating unit that calculates the EGR valve target differential pressure in accordance with a closing degree of the throttle valve. apparatus.

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