JP2020148095A - Engine system - Google Patents

Abstract

To obtain, for example, a distance or an area of an opening between a valve seat and a valve body of an EGR valve due to jamming by a contaminant with high accuracy regardless of a tolerance in a detection value of intake system detection means including an intake pressure sensor and an air flowmeter.SOLUTION: An engine system comprises: an engine 1; an intake passage 3; an exhaust passage 5; an EGR device 10; an intake pressure sensor 51; and an electronic control unit (ECU) 50. The EGR device 10 includes: an EGR passage 17 which circulates a portion of exhaust discharged from the engine 1 into the exhaust passage 5 back to the engine through the intake passage 3 as EGR gas; and an EGR valve 18 which adjusts a flow rate of the EGR gas in the EGR passage 17. The ECU 50 controls at least an EGR valve 18 on the basis of a detected operation state; and calculates a distance or an area of an opening between a valve seat and a valve body 33, when fully closing the EGR valve 18, on the basis of a detected intake pressure. In addition, the ECU 50 corrects the distance or the area of the opening taking into consideration a tolerance in a detection value of the intake pressure sensor 51.SELECTED DRAWING: Figure 1

Description

The technology disclosed herein relates to an engine system comprising an EGR device that recirculates part of the engine's exhaust as EGR gas to the engine.

Conventionally, as this kind of technology, for example, the technology "engine exhaust recirculation device" described in Patent Document 1 below is known. This technology includes an EGR passage that allows a part of the exhaust gas discharged from the engine to the exhaust passage to flow as EGR gas to the intake passage and returns it to the engine, an EGR valve that regulates the EGR gas flow rate in the EGR passage, and intake in the intake passage. An electronic control unit (ECU) that detects foreign matter biting in the EGR valve based on the intake pressure sensor that detects the pressure and the detection value of the intake pressure sensor, and also executes control to remove the foreign matter when the foreign matter biting is determined. ) And. Here, the ECU slightly increases the opening degree of the EGR valve from the fully closed state in a stepwise manner, and sets the opening degree at which the intake pressure detected by the intake pressure sensor changes to the foreign matter biting position (foreign matter biting open). It is determined as a degree (separation distance or opening area between the valve seat and the valve body), and is determined to be an abnormality due to foreign matter biting.

Japanese Unexamined Patent Publication No. 2013-249774

However, in the technique described in Patent Document 1, the intake pressure sensor is used to determine the foreign matter biting position (foreign matter biting opening degree (separation distance or opening area between the valve seat and the valve body)) of the EGR valve. Although the detected value is used, the intake pressure sensor has a product tolerance, so that the detected value may have a tolerance deviation. If there is a tolerance deviation in this detected value, it may not be possible to properly determine the foreign matter biting opening degree even though the EGR valve has foreign matter biting. As a result, it is not possible to properly determine whether foreign matter is caught, EGR gas leaks into the engine, and in some cases, engine stall may not be avoided. On the other hand, in order to determine the foreign matter biting opening degree of the EGR valve, it is also possible to use an air flow meter that detects the amount of intake air flowing through the intake passage instead of the intake pressure sensor. In this case as well, due to the tolerance deviation in the detected value of the air flow meter, the opening degree of foreign matter biting cannot be properly determined, and by extension, the biting of foreign matter cannot be properly determined, resulting in engine stall. It may not be possible to avoid it.

This disclosure technique has been made in view of the above circumstances, and the purpose thereof is, for example, foreign matter biting regardless of whether or not there is a tolerance deviation of the detection values of the intake system detecting means including the intake pressure sensor and the air flow meter. It is an object of the present invention to provide an engine system capable of obtaining a separation distance or an opening area between a valve seat and a valve body of an EGR valve caused by the above with high accuracy.

In order to achieve the above object, the technique according to claim 1 includes an engine, an intake passage for introducing intake air into the engine, an exhaust passage for deriving exhaust from the engine, and exhaust from the engine to the exhaust passage. The EGR device includes an EGR passage for flowing a part of the exhaust gas to the intake passage as EGR gas and returning it to the engine, and an EGR valve for adjusting the flow rate of the EGR gas in the EGR passage, and the EGR valve is The valve seat, the valve body provided so as to be seated on the valve seat, the operating state detecting means for detecting the operating state of the engine, and the operating state detecting means are introduced into the engine in the intake passage. When the intake system detection means for detecting the pressure or flow rate of the intake air is included, the control means for controlling at least the EGR valve based on the detected operating state, and the EGR valve is controlled to be fully closed. In an engine system provided with a calculation means for calculating the separation distance or opening area between the valve seat and the valve body based on the detected intake pressure or flow rate, the calculation means is a detection value of the intake system detection means. The purpose is to calculate the separation distance or the opening area after correcting the tolerance deviation of. Here, the "separation distance or opening area between the valve seat and the valve body" is, for example, the opening due to the valve opening sticking caused by foreign matter being caught between the valve seat and the valve body of the EGR valve. It means that it corresponds to the diameter of the foreign matter bitten between the valve seat and the valve body.

According to the configuration of the above technique, when the EGR valve is controlled to be fully closed, the valve seat and the valve are corrected based on the corrected intake pressure or flow rate after correcting the tolerance deviation of the detection value of the intake system detecting means. The separation distance or opening area from the body is calculated. Therefore, for example, when a foreign matter is caught in the EGR valve, the variation in the calculation result of the separation distance or the opening area is reduced.

In order to achieve the above object, the technique according to claim 2 is the technique according to claim 1. In the technique according to claim 1, the calculation means changes the calculated separation distance or opening area as the engine speed changes. In this case, the purpose is to correct the pressure or flow rate of the intake air detected so that the fluctuation of the separation distance or the opening area disappears.

According to the configuration of the above technique, in addition to the action of the technique according to claim 1, even if the calculated separation distance or opening area fluctuates with a change in the engine speed, it is detected so that the fluctuation disappears. The pressure or flow rate of the intake air is corrected. Therefore, even if the engine speed changes, the variation in the calculation result of the separation distance or the opening area becomes small, for example, when foreign matter is caught in the EGR valve.

In order to achieve the above object, the technique according to claim 3 is the technique according to claim 1 or 2, wherein the calculation means raises the EGR valve to an opening degree corresponding to the calculated separation distance or opening area. When the valve is opened and the detected intake air pressure or flow rate does not change, the opening of the EGR valve is increased until the detected intake air pressure or flow rate changes, and the detected intake air pressure or flow rate changes. The purpose is to correct the opening when it changes as the separation distance or the opening area.

According to the configuration of the above technique, in addition to the action of the technique according to claim 1 or 2, even if there is an error in the calculated separation distance or opening area, a more appropriate separation distance or opening that eliminates the error. The area is calculated.

In order to achieve the above object, the technique according to claim 4 is the technique according to any one of claims 1 to 3, wherein the calculation means reaches an opening degree corresponding to the calculated separation distance or opening area. When the EGR valve is opened and the detected intake air pressure or flow rate changes, the opening of the EGR valve is reduced until the detected intake air pressure or flow rate does not change, and the detected intake air pressure or flow rate is reduced. The purpose is to correct the opening degree when the flow rate does not change as the separation distance or the opening area.

According to the configuration of the above technique, in addition to the action of the technique according to any one of claims 1 to 3, even if there is an error in the calculated separation distance or opening area, a more appropriate separation that eliminates the error is eliminated. The distance or opening area is calculated.

In order to achieve the above object, the technique according to claim 5 is arranged in the intake passage in the technique according to any one of claims 1 to 4, and the intake amount for adjusting the intake amount flowing through the intake passage is adjusted. A control valve and an engine stall avoidance processing means for avoiding the engine stall are further provided, the operating state detecting means further includes a rotation speed detecting means for detecting the engine speed, and the engine stall avoiding processing means is a calculation means. When the separation distance or opening area is calculated by, the target idle speed is set to a set value larger than the predetermined basic idle speed, and the set target idle speed is set according to the current engine speed of the engine. The purpose is to control the intake amount control valve so that the corrected and detected engine speed becomes the corrected target idle speed.

According to the configuration of the above technique, in addition to the action of the technique according to any one of claims 1 to 4, the detected engine speed is corrected even if there is an error in the calculated separation distance or opening area. The intake amount control valve is controlled so as to reach the set target idle speed, and engine stall is avoided.

According to the technique according to claim 1, the valve seat and valve of the EGR valve caused by, for example, foreign matter biting, regardless of whether or not there is a tolerance deviation of the detection values of the intake system detecting means including the intake pressure sensor and the air flow meter. The separation distance or opening area between the body and the body can be obtained with high accuracy. As a result, for example, an abnormality caused by sticking of the EGR valve open can be diagnosed with high accuracy.

According to the technique according to claim 2, in addition to the effect of the technique according to claim 1, the separation distance or opening area between the valve seat and the valve body is further increased regardless of the change in the engine speed. It can be calculated with accuracy.

According to the technique of claim 3, in addition to the effect of the technique of claim 1 or 2, the calculation accuracy of the distance or opening area is further increased regardless of the error of the calculated distance or opening area. Can be improved.

According to the technique according to claim 4, in addition to the effect of the technique according to any one of claims 1 to 3, the calculation of the separation distance or the opening area is performed regardless of the calculated error of the separation distance or the opening area. The accuracy can be further improved.

According to the technique according to claim 5, in addition to the effect of the technique according to any one of claims 1 to 4, due to unnecessary reflux of the EGR gas regardless of the calculated separation distance or the error of the opening area. The engine stall can be avoided properly.

The schematic block diagram which shows the engine system which concerns on 1st Embodiment. FIG. 5 is a cross-sectional view showing the configuration of an EGR valve according to the first embodiment. An enlarged cross-sectional view showing a part of an EGR valve according to the first embodiment. The flowchart which shows an example of the processing content of the foreign matter biting diagnosis control which concerns on 1st Embodiment. The flowchart which shows an example (continuation) of the processing content of the foreign matter biting diagnosis control which concerns on 1st Embodiment. The fully closed reference intake pressure map referred to in order to obtain the fully closed reference intake pressure according to the engine speed and the engine load according to the first embodiment. The intake pressure increase allowance map referred to in order to calculate the intake pressure increase allowance according to the foreign matter diameter and the engine speed according to the first embodiment. According to the first embodiment, the central upper and lower limit tolerances of the abnormality determination in the relationship between the foreign matter diameter determined based on the intake pressure (when the determination foreign matter diameter = 0.6 (in the case of abnormality)) and the engine speed A graph showing the judgment result. According to the first embodiment, the determination result of the central upper / lower limit tolerance of the normal determination in relation to the foreign matter diameter (when the judgment foreign matter diameter = 0 (normal case)) determined based on the intake pressure and the engine speed. Graph showing. A graph showing the relationship between the intake pressure and the intake amount for determining the foreign matter diameter in the case of low rotation and the product tolerance of the intake pressure sensor and the air flow meter according to the first embodiment. A graph showing the relationship between the intake pressure and the intake amount for determining the foreign matter diameter in the case of the first intermediate rotation and the product tolerance of the intake pressure sensor and the air flow meter according to the first embodiment. A graph showing the relationship between the intake pressure and the intake amount for determining the foreign matter diameter in the case of the second intermediate rotation and the product tolerance of the intake pressure sensor and the air flow meter according to the first embodiment. A graph showing the relationship between the intake pressure and the intake amount for determining the foreign matter diameter in the case of high rotation and the product tolerance of the intake pressure sensor and the air flow meter according to the first embodiment. The flowchart which shows the content of the tolerance deviation inclination determination processing which concerns on 1st Embodiment. The flowchart which shows the content of the calculation process of the correction intake pressure which concerns on 1st Embodiment. A flowchart showing the calculation content of the final foreign matter diameter according to the second embodiment. The foreign matter diameter equivalent opening map referred to in order to obtain the foreign matter diameter equivalent opening degree according to the foreign matter diameter according to the second embodiment. FIG. 5 is a flowchart showing an example of idle-up control content during deceleration according to the third embodiment. The first idle-up speed map referred to in order to obtain the first idle-up speed according to the engine speed and the foreign matter diameter according to the third embodiment. The second idle-up speed map referred to in order to obtain the second idle-up speed according to the engine speed and the foreign matter diameter according to the third embodiment. A time chart showing an example of the behavior of various parameters by idle-up control according to the third embodiment.

<First Embodiment>
Hereinafter, the first embodiment in which the engine system is embodied as a gasoline engine system will be described in detail with reference to the drawings.

[Overview of engine system]
FIG. 1 shows a schematic configuration diagram of a gasoline engine system (hereinafter, simply referred to as “engine system”) in this embodiment. The engine system mounted on the vehicle includes a reciprocating type gasoline engine (hereinafter, simply referred to as "engine") 1. An intake passage 3 is connected to the intake port 2 of the engine 1, and an exhaust passage 5 is connected to the exhaust port 4. An air cleaner 6 is provided at the entrance of the intake passage 3.

The intake passage 3 includes a surge tank 3a, and an electronic throttle device 14 for adjusting the amount of intake air flowing through the intake passage 3 is provided in the intake passage 3 upstream of the surge tank 3a. The electronic throttle device 14 includes a throttle valve 21, a DC motor 22 for driving the throttle valve 21 to open and close, and a throttle sensor 23 for detecting the opening degree (throttle opening degree) TA of the throttle valve 21. In the electronic throttle device 14, the opening degree of the throttle valve 21 is adjusted by driving the DC motor 22 in response to the operation of the accelerator pedal 26 by the driver. The electronic throttle device 14 including the throttle valve 21 corresponds to an example of an intake air amount control valve in the disclosed technology. The exhaust passage 5 is provided with a catalytic converter 15 for purifying the exhaust gas.

The engine 1 is provided with an injector 25 for injecting and supplying fuel (gasoline) to the combustion chamber 16. Fuel is supplied to the injector 25 from a fuel tank (not shown). Further, the engine 1 is provided with an ignition device 29 for igniting a mixture of fuel and intake air formed in the combustion chamber 16.

The engine system is provided with a high pressure loop type exhaust gas recirculation device (EGR device) 10. The EGR device 10 is a device for returning a part of the exhaust gas discharged from the combustion chamber 16 of the engine 1 to the exhaust passage 5 to the combustion chamber 16 as an exhaust gas recirculation gas (EGR gas). The EGR device 10 includes an exhaust gas recirculation passage (EGR passage) 17 for flowing EGR gas from the exhaust passage 5 to the intake passage 3, and an exhaust gas recirculation provided in the passage 17 for adjusting the flow rate of the EGR gas in the EGR passage 17. A valve (EGR valve) 18 is provided. The EGR passage 17 is provided between the exhaust passage 5 and the intake passage 3 (surge tank 3a). That is, the outlet 17a of the EGR passage 17 is connected to the surge tank 3a downstream from the electronic throttle device 14. The inlet 17b of the EGR passage 17 is connected to the exhaust passage 5 upstream of the catalytic converter 15.

The EGR passage 17 is provided with an EGR cooler 20 for cooling the EGR gas flowing through the passage 17. In this embodiment, the EGR valve 18 is arranged in the EGR passage 17 downstream of the EGR cooler 20.

[About the configuration of the EGR valve]
FIG. 2 shows the configuration of the EGR valve 18 in a cross-sectional view. FIG. 3 shows a part of the EGR valve 18 by an enlarged cross-sectional view. As shown in FIG. 2, the EGR valve 18 is composed of a poppet type electric valve. That is, the EGR valve 18 includes a housing 31, a valve seat 32 provided in the housing 31, a valve body 33 provided in the housing 31 so as to be seatable and movable with respect to the valve seat 32, and a valve body 33. It is provided with a step motor 34 for making a stroke movement. The housing 31 has an introduction port 31a in which EGR gas is introduced from the exhaust passage 5 side (exhaust side), an outlet 31b for leading EGR gas to the intake passage 3 side (intake side), and an introduction port 31a. Includes a communication passage 31c that communicates with the exit 31b. The valve seat 32 is provided in the middle of the communication passage 31c.

The step motor 34 includes an output shaft 35 configured to be able to reciprocate (stroke movement) linearly, and a valve body 33 is fixed to the tip of the output shaft 35. The output shaft 35 is supported in a stroke movable manner with respect to the housing 31 via a bearing 36 provided in the housing 31. A male screw portion 37 is formed at the upper end portion of the output shaft 35. A spring receiver 38 is provided in the middle of the output shaft 35 (near the lower end of the male screw portion 37). The lower surface of the spring receiver 38 is the receiving surface of the compression spring 39, and the stopper 40 is formed on the upper surface.

The valve body 33 has a conical shape, and the conical surface is in contact with or separated from the valve seat 32. When the valve body 33 comes into contact with the valve seat 32, the valve body 33 is fully closed, and when the valve body 33 is separated from the valve seat 32, the valve body 33 is opened. The valve body 33 is urged toward the step motor 34 by a compression spring 39 provided between the spring receiver 38 and the housing 31, that is, in the valve closing direction in which the valve seat 32 is seated. .. Then, the valve body 33 in the fully closed state moves in a stroke against the urging force of the compression spring 39 by the output shaft 35 of the step motor 34, so that the valve body 33 is separated from the valve seat 32 (valve opening). To do. At the time of this valve opening, the valve body 33 moves toward the upstream side (exhaust side) of the EGR passage 17. In this way, the EGR valve 18 moves from the fully closed state in which the valve body 33 is seated on the valve seat 32 to the upstream side of the EGR passage 17 against the exhaust pressure or the intake pressure of the engine 1. The body 33 opens the valve away from the valve seat 32. On the other hand, from the valve open state, the valve body 33 is moved in the urging direction of the compression spring 39 by the output shaft 35 of the step motor 34, so that the valve body 33 approaches the valve seat 32 and closes the valve. At the time of this valve closing, the valve body 33 moves toward the downstream side (intake side) of the EGR passage 17.

In this embodiment, the opening degree of the valve body 33 with respect to the valve seat 32 is adjusted by making the output shaft 35 of the step motor 34 stroke. The output shaft 35 of the EGR valve 18 is capable of stroke movement by a predetermined stroke from the fully closed state in which the valve body 33 is seated on the valve seat 32 to the fully open state in which the valve body 33 is maximally separated from the valve seat 32. It is provided.

The step motor 34 includes a coil 41, a magnet rotor 42, and a conversion mechanism 43. The step motor 34 rotates the magnet rotor 42 by a predetermined number of motor steps when the coil 41 is excited by energization, and the conversion mechanism 43 converts the rotational motion of the magnet rotor 42 into the stroke motion of the output shaft 35. It has become. Along with the stroke movement of the output shaft 35, the valve body 33 makes a stroke movement with respect to the valve seat 32.

The magnet rotor 42 includes a resin rotor body 44 and an annular plastic magnet 45. At the center of the rotor body 44, a female threaded portion 46 screwed into the male threaded portion 37 of the output shaft 35 is formed. When the rotor body 44 rotates while the female threaded portion 46 of the rotor body 44 and the male threaded portion 37 of the output shaft 35 are screwed together, the rotational motion is converted into the stroke motion of the output shaft 35. Here, the male screw portion 37 and the female screw portion 46 form the above-mentioned conversion mechanism 43. At the lower part of the rotor main body 44, a contact portion 44a with which the stopper 40 of the spring receiver 38 comes into contact is formed. When the EGR valve 18 is fully closed, the end face of the stopper 40 comes into surface contact with the end face of the contact portion 44a, and the initial position of the output shaft 35 is regulated.

In this embodiment, the opening degree of the valve body 33 of the EGR valve 18 is adjusted to be finely adjusted stepwise from the fully closed state to the fully open state by stepwise changing the number of motor steps of the step motor 34. ing.

[About the electrical configuration of the engine system]
As shown in FIG. 1, the engine system of this embodiment includes an electronic control unit (ECU) 50 that controls various controls. The ECU 50 controls the injector 25, the ignition device 29, the electronic throttle device 14 (DC motor 22), and the EGR valve 18 (step motor 34) according to the operating state of the engine 1. The ECU 50 includes a central processing unit (CPU), various memories for storing predetermined control programs and the like in advance, and temporarily storing the calculation results of the CPU, and an external input circuit and an external device connected to each of these parts. It has an output circuit. The ECU 50 corresponds to an example of a control means and a calculation means in this disclosure technique. An injector 25, an ignition device 29, an electronic throttle device 14 (DC motor 22), and an EGR valve 18 (step motor 34) are connected to the external output circuit. Various sensors 27, 51 to 55 for detecting the operating state of the engine 1 including the throttle sensor 23 are connected to the external input circuit. The various sensors 23, 27, 51 to 55 correspond to an example of the operating state detecting means in the disclosed technology.

Here, as various sensors, in addition to the throttle sensor 23, an accelerator sensor 27, an intake pressure sensor 51, a rotation speed sensor 52, a water temperature sensor 53, an air flow meter 54, and an air-fuel ratio sensor 55 are provided. The accelerator sensor 27 detects the amount of operation of the accelerator pedal 26 as the accelerator opening degree ACC and outputs the detection signal. The intake pressure sensor 51 detects the intake pressure introduced into the engine 1 in the intake passage 3 (surge tank 3a) downstream of the electronic throttle device 14 (throttle valve 21) and into which the EGR gas flows, as the intake pressure PM. The detection signal is output. The intake pressure sensor 51 corresponds to an example of the intake system detecting means in the disclosed technique. The rotation speed sensor 52 detects the rotation angle (crank angle) of the crankshaft 1a of the engine 1 and detects the change in the crank angle (crank angular velocity) as the rotation speed (engine rotation speed) NE of the engine 1, and the change thereof is detected. It is designed to output a detection signal. The rotation speed sensor 52 corresponds to an example of the rotation speed detecting means in the disclosed technology. The water temperature sensor 53 detects the temperature of the cooling water flowing inside the engine 1 as the cooling water temperature THW, and outputs the detection signal. The air flow meter 54 flows through the intake passage 3 immediately downstream of the air cleaner 6, detects the flow rate of the intake air introduced into the engine 1 as the intake air amount Ga, and outputs the detection signal. The air flow meter 54 also corresponds to an example of the intake system detecting means in the disclosed technique. The air-fuel ratio sensor 55 detects the air-fuel ratio A / F in the exhaust in the exhaust passage 5 directly upstream of the catalyst converter 15 and outputs the detection signal. The throttle sensor 23, the intake pressure sensor 51, the rotation speed sensor 52, or the air flow meter 54 constitute an example of load detecting means for detecting the load of the engine 1.

In this embodiment, the ECU 50 controls at least the EGR valve 18 according to the operating state of the engine 1 in order to execute the EGR control in the entire operating region of the engine 1. On the other hand, the ECU 50 controls the EGR valve 18 to be fully closed in order to shut off the EGR when the engine 1 is decelerated.

Here, in the EGR valve 18, for example, as shown in FIG. 3, there may be a problem that foreign matter FB such as a deposit is caught or adhered between the valve seat 32 and the valve body 33. Therefore, in this embodiment, the ECU 50 engages between the valve seat 32 and the valve body 33 in order to diagnose an abnormality caused by the valve opening sticking (not closing while being open) of the EGR valve 18 including foreign matter biting. To execute the "foreign matter biting diagnostic control" including the calculation of the diameter of the foreign matter FB (corresponding to the separation distance between the valve seat 32 and the valve body 33 of the EGR valve 18 in this disclosure technique). It has become.

[Foreign matter biting diagnostic control]
4 and 5 show an example of the processing content of the “foreign matter biting diagnosis control” executed by the ECU 50 by a flowchart. This flowchart is a process for diagnosing an abnormality due to foreign matter biting (valve opening sticking) of the EGR valve 18 when the EGR valve 18 is controlled to be fully closed or when the EGR valve 18 is controlled to be fully closed during deceleration of the engine 1. Is shown.

When the process shifts to this routine, first, in step 100, the ECU 50 takes in the engine speed NE, the engine load KL, the throttle opening TA, the intake amount Ga, and the motor step number STegr, respectively. Further, the ECU 50 takes in the corrected intake pressure KPM calculated based on the detected (acquired) intake pressure PM. Here, the ECU 50 can obtain the engine load KL based on the throttle opening TA, the intake pressure PM, the engine speed NE, or the intake amount Ga. The corrected intake pressure KPM is a parameter obtained by correcting the detected intake pressure PM by a predetermined calculation method in order to eliminate the product tolerance (including the tolerance of the detected value) of the intake pressure sensor 51. The calculation method of this corrected intake pressure KPM will be described later.

Next, in step 110, the ECU 50 determines whether or not the operating state of the engine 1 is within the foreign matter biting detection range. The ECU 50 can determine, for example, whether the range defined by the relationship between the engine speed NE and the engine load KL is within a predetermined range suitable for detecting foreign matter biting. Within this predetermined range, deceleration operation or steady operation of the engine 1 is included. If the determination result is affirmative, the ECU 50 shifts the process to step 120, and if the determination result is negative, the ECU 50 returns the process to step 100.

In step 120, the ECU 50 determines whether or not the number of motor steps STegr is smaller than "8 steps". “8 steps” is an example and corresponds to a minute opening degree of the EGR valve 18. Here, when the number of motor steps STegr is "8 steps or less", it corresponds to the fully closed control of the EGR valve 18. If the determination result is affirmative, the ECU 50 shifts the process to step 130, and if the determination result is negative, the ECU 50 returns the process to step 100.

In step 130, the ECU 50 takes in the fully closed reference intake pressure PMegr0 at the time of deceleration according to the engine speed NE and the engine load KL. The ECU 50 determines the detected (acquired) engine speed NE and the detected (acquired) engine load KL by referring to the fully closed reference intake pressure map set in advance as shown in FIG. 6, for example. The fully closed reference intake pressure PMegr0 at the time of deceleration can be calculated accordingly. In this fully closed reference intake pressure map, the relationship between the fully closed reference intake pressure PMegr0 with respect to the engine speed NE and the engine load KL when the opening degree of the valve body 33 of the EGR valve 18 is "0", that is, when fully closed is preset. It is a map that has been made. In general, the intake pressure PM during deceleration of the engine 1 has a correlation with the engine load KL regardless of the presence or absence of foreign matter being caught in the EGR valve 18, and both are substantially proportional to each other. However, since the intake pressure PM changes according to the engine speed NE, the fully closed reference intake pressure PMegr0 is set for the engine speed NE and the engine load KL in FIG.

Next, in step 140, the ECU 50 determines the diameter (foreign matter diameter) of the foreign matter FB bitten into the EGR valve 18 (foreign matter diameter) ΦX (X = -0.6, -0.3, 0.3, 0.3, 0.6). 0.9) and the intake pressure increase allowance αΦX (X = -0.6, -0.3, 0, 0.3, 0.6, 0.9) corresponding to the engine speed NE are obtained. The ECU 50 obtains, for example, an intake pressure increase allowance αΦX according to the engine speed NE detected (acquired) as a foreign matter diameter ΦX by referring to a preset intake pressure increase allowance map as shown in FIG. Can be calculated. The intake pressure increase allowance αΦX is the amount of increase in the intake pressure PM caused by the EGR valve 18 becoming stuck in the valve opening and not closing due to the foreign matter FB being caught when the EGR valve 18 is controlled to close. means. Therefore, as shown in FIG. 7, the intake pressure increase allowance αΦX increases because the opening degree due to the sticking of the EGR valve 18 increases as the foreign matter diameter ΦX increases. As the engine speed NE increases, the intake amount Ga taken into the engine 1 per rotation decreases, so that the intake pressure increase allowance αΦX becomes smaller. In FIG. 7, the thick one-point chain wire has a foreign matter diameter ΦX of “0.9 (mm)”, the thick broken line has a foreign matter diameter ΦX of “0.6 (mm)”, and the thick two-point chain wire has a foreign matter diameter ΦX. When is "0.3 (mm)", the thick solid line is thin when the foreign matter diameter ΦX is "0 (mm)", and the thin two-point chain wire is thin when the foreign matter diameter ΦX is "-0.3 (mm)". The broken line indicates the case where the foreign matter diameter ΦX is “-0.6 (mm)”. Therefore, here, when the foreign matter diameter ΦX is "-0.6 (mm)", the intake pressure increase allowance is shown as "αΦ-0.6", and the foreign matter diameter ΦX is "-0.3 (mm)". The intake pressure increase allowance in the case is indicated as "αΦ-0.3", the intake pressure increase allowance when the foreign matter diameter ΦX is "0 (mm)" is indicated as "αΦ0", and the foreign matter diameter ΦX is "0.3 ( The allowance for increasing the intake pressure in the case of "mm)" is indicated as "αΦ0.3", and the allowance for increasing the intake pressure when the foreign matter diameter ΦX is "0.6 (mm)" is indicated as "αΦ0.6", and the foreign matter diameter ΦX. The intake pressure increase allowance when is "0.9 (mm)" is shown as "αΦ0.9". That is, in this step 140, the ECU 50 has a plurality of foreign matter diameters ΦX (Φ-0.6, Φ-0.3, Φ0, Φ0.3,) in which foreign matter is assumed to be caught in the EGR valve 18 (valve opening sticking). Φ0.6, Φ0.9) and multiple intake pressure increase allowances αΦX (αΦ-0.6, αΦ-0, αΦ0.3, αΦ0.3, αΦ0.6, αΦ0. 9) is calculated.

Next, in step 150, the ECU 50 determines whether or not the corrected intake pressure KPM taken in is larger than the addition result (PMegr0 + αΦ-0.3) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ-0.3. To judge. Therefore, the ECU 50 obtains an addition result (PMegr0 + αΦ-0.3) by adding the intake pressure increase allowance αΦ-0.3 to the fully closed reference intake pressure PMegr0. If the determination result is affirmative, the ECU 50 shifts the process to step 160 assuming that the foreign matter diameter ΦX is “−0.3 (mm) or more”, and if this determination result is negative, the foreign matter is found. The process proceeds to step 300 assuming that the diameter ΦX is “−0.6 to −0.3 (mm)”. Here, the reason why a negative value is set for the foreign matter diameter ΦX is that when the product tolerance shifts to the lower limit side, it may be judged as normal even if the foreign matter is caught, so the judgment of a negative value is made. By setting the value, the product tolerance deviation on the upper limit side can be determined by the inclination.

Next, in step 160, the ECU 50 determines whether or not the captured corrected intake pressure KPM is larger than the addition result (PMegr0 + αΦ0) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0. Therefore, the ECU 50 obtains an addition result (PMegr0 + αΦ0) by adding the intake pressure increase allowance αΦ0 to the fully closed reference intake pressure PMegr0. If this determination result is affirmative, the ECU 50 proceeds to step 170 assuming that the foreign matter diameter ΦX is “0 (mm) or more”, and if this determination result is negative, the foreign matter diameter ΦX is The process proceeds to step 310 assuming that the value is "−0.3 to 0 (mm)".

Next, in step 170, the ECU 50 determines whether or not the captured corrected intake pressure KPM is larger than the addition result (PMegr0 + αΦ0.3) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.3. .. Therefore, the ECU 50 obtains an addition result (PMegr0 + αΦ0.3) by adding the intake pressure increase allowance αΦ0.3 to the fully closed reference intake pressure PMegr0. If this determination result is affirmative, the ECU 50 shifts the process to step 180 assuming that the foreign matter diameter ΦX is “0.3 (mm) or more”, and if this determination result is negative, the foreign matter diameter The process proceeds to step 230 assuming that ΦX is “0 to 0.3 (mm)”.

In step 180, the ECU 50 determines whether or not the captured corrected intake pressure KPM is larger than the addition result (PMegr0 + αΦ0.6) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.6. Therefore, the ECU 50 obtains an addition result (PMegr0 + αΦ0.6) by adding the intake pressure increase allowance αΦ0.6 to the fully closed reference intake pressure PMegr0. If this determination result is affirmative, the ECU 50 shifts the process to step 190 assuming that the foreign matter diameter ΦX is “0.6 (mm) or more”, and if this determination result is negative, the foreign matter diameter The process proceeds to step 280 assuming that ΦX is “0.3 to 0.6 (mm)”.

In step 190, the ECU 50 determines whether or not the captured corrected intake pressure KPM is larger than the addition result (PMegr0 + αΦ0.9) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.9. Therefore, the ECU 50 obtains an addition result (PMegr0 + αΦ0.9) by adding the intake pressure increase allowance αΦ0.9 to the fully closed reference intake pressure PMegr0. If this determination result is affirmative, the ECU 50 shifts the process to step 200 assuming that the foreign matter diameter ΦX is “0.9 (mm) or more”, and if this determination result is negative, the foreign matter diameter The process proceeds to step 290 assuming that ΦX is “0.6 to 0.9 (mm)”.

In step 200, the ECU 50 determines that the foreign matter diameter ΦX is “0.9 (mm) or more”. That is, the ECU 50 calculates the foreign matter diameter ΦX by the processing before step 200, and obtains the calculation result of “0.9 (mm) or more”.

Next, in step 210, the ECU 50 determines that the EGR valve 18 has caused an abnormality due to foreign matter biting. The ECU 50 can store the determination result in the memory and execute a predetermined notification control for the driver.

Next, in step 220, the ECU 50 executes idle-up control according to the determined foreign matter diameter ΦX. In this case, the ECU 50 executes idle-up control according to the foreign matter diameter ΦX of 0.9 (mm) or more. That is, if foreign matter is caught in the EGR valve 18 during deceleration of the engine 1, unnecessary EGR gas leaks to the engine 1, and there is a risk of misfire, deterioration of drivability, or engine stall in the engine 1. These stalls and the like are more likely to occur as the foreign matter diameter ΦX increases, that is, as the flow rate of EGR gas leaking to the engine 1 increases. Therefore, in this embodiment, the ECU 50 executes idle-up control according to the foreign matter diameter ΦX in order to avoid these engine stalls and the like. After that, the ECU 50 returns the process to step 100.

On the other hand, in step 230, the ECU 5 shifts from step 170 to the fully closed reference intake pressure PMegr0 from the addition result (PMegr0 + αΦ0) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0. The foreign matter diameter ΦX is obtained by performing an interpolation calculation between the addition result (PMegr0 + αΦ0.3) of the intake pressure increase allowance αΦ0.3. That is, the ECU 50 has acquired the correction for the opening degree between the assumed foreign matter diameters ΦX (Φ-0.6, Φ-0.3, Φ0, Φ0.3, Φ0.6, Φ0.9). The intake pressure KPM is obtained by interpolation calculation between two adjacent addition results (PMegr0 + αΦ0, PMegr0 + αΦ0.3) having close values among a plurality of calculated addition results (PMegr0 + αΦX). The ECU 50 can adopt, for example, the following calculation formula 1 (F1) for the interpolation calculation.
ΦX = [1- (PMegr0 + αΦ0.3-KPM) / (PMegr0 + αΦ0.3-PMegr0)] * (Φ0.3-Φ0) + Φ0 ... (F1)

Next, in step 240, the ECU 50 determines that the foreign matter diameter ΦX is the value obtained in the immediately preceding step. In this case, the ECU 50 determines that the foreign matter diameter ΦX is a value in the range of “0 to 0.3 (mm)”. That is, the ECU 50 calculates the foreign matter diameter ΦX by the interpolation calculation before step 240, and obtains a certain determination result.

Next, in step 250, the ECU 50 determines whether or not the determined foreign matter diameter ΦX is “approximately 0” or less. Here, "substantially 0" includes "0 and a value extremely close to 0 that allows a calculation error". If the determination result is affirmative, the ECU 50 shifts the process to step 260 assuming that there is no foreign matter biting, and if this determination result is negative, the ECU 50 proceeds to step 210 assuming that there is foreign matter biting. The transition is performed, and the processes after step 210 are executed.

In step 260, the ECU 50 determines that the EGR valve 18 is normal because it does not cause an abnormality due to foreign matter biting. The ECU 50 can store this determination result in the memory.

Next, in step 270, the ECU 50 executes idle control when the EGR valve 18 is normal. That is, if there is no foreign matter caught in the EGR valve 18 when the engine 1 is decelerated, there is no possibility of engine stall or the like due to the inflow of EGR gas into the engine 1, so that the ECU 50 executes normal idle control. After that, the ECU 50 returns the process to step 100.

On the other hand, in step 280 after shifting from step 180, the ECU 5 fully closes the captured corrected intake pressure KPM from the addition result (PMegr0 + αΦ0.3) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.3. The foreign matter diameter ΦX is obtained by performing an interpolation calculation between the addition result (PMegr0 + αΦ0.6) of the reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.6. Here, the ECU 50 obtains the acquired corrected intake pressure KPM by performing an interpolation calculation between two adjacent addition results (PMegr0 + αΦ0.3, PMegr0 + αΦ0.6) having close values. The ECU 50 can adopt, for example, the following calculation formula 2 (F2) for the interpolation calculation.
ΦX = [1- (PMegr0 + αΦ0.6-KPM) / (PMegr0 + αΦ0.6-PMegr0-αΦ0.3)] * (Φ0.6-Φ0.3) + Φ0.3 ... (F2)

After that, the ECU 50 shifts the process to step 240 and executes the processes after step 240.

On the other hand, in step 290 after shifting from step 190, the ECU 5 fully closes the captured corrected intake pressure KPM from the addition result (PMegr0 + αΦ0.6) of the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.6. The foreign matter diameter ΦX is obtained by performing an interpolation calculation between the addition result (PMegr0 + αΦ0.9) of the reference intake pressure PMegr0 and the intake pressure increase allowance αΦ0.9. Here, the ECU 50 obtains the acquired corrected intake pressure KPM by performing an interpolation calculation between two adjacent addition results (PMegr0 + αΦ0.6, PMegr0 + αΦ0.9) having close values. The ECU 50 can adopt, for example, the following calculation formula 3 (F3) for the interpolation calculation.
ΦX = [1- (PMegr0 + αΦ0.9-KPM) / (PMegr0 + αΦ0.9-PMegr0-αΦ0.6)] * (Φ0.9-Φ0.6) + Φ0.6 ... (F3)

After that, the ECU 50 shifts the process to step 240 and executes the processes after step 240.

On the other hand, in step 300 after shifting from step 150, the ECU 5 adds the incorporated corrected intake pressure KPM to the fully closed reference intake pressure PMegr0 and the intake pressure increase allowance αΦ-0.6 (PMegr0 + αΦ-0.6). ), The foreign matter diameter ΦX is obtained by performing an interpolation calculation between the addition result (PMegr0 + αΦ-0.3) of the fully closed reference intake pressure PMegr0 and the intake pressure rise allowance αΦ-0.3. Here, the ECU 50 obtains the acquired corrected intake pressure KPM by performing an interpolation calculation between two adjacent addition results (PMegr0 + αΦ-0.6, PMegr0 + αΦ-0.3) having close values. For the interpolation calculation, the ECU 50 can adopt, for example, a calculation formula similar to the above-mentioned calculation formulas (F1 to F3).

After that, the ECU 50 shifts the process to step 240 and executes the processes after step 240.

On the other hand, in step 310 after shifting from step 160, the ECU 5 adds the corrected intake pressure KPM taken in by adding the intake pressure increase allowance αΦ-0.3 from the fully closed reference intake pressure PMegr0 (PMegr0-αΦ-). The foreign matter diameter ΦX is obtained by performing an interpolation calculation between the subtraction results (PMegr0-αΦ0) obtained by subtracting the intake pressure increase allowance αΦ0 from the fully closed reference intake pressure PMegr0 from 0.3). Here, the ECU 50 obtains the acquired corrected intake pressure KPM by performing an interpolation calculation between two adjacent subtraction results (PMegr0-αΦ-0.3, PMegr0-αΦ0) having close values. For the interpolation calculation, the ECU 50 can adopt, for example, a calculation formula similar to the above-mentioned calculation formulas (F1 to F3).

After that, the ECU 50 shifts the process to step 240 and executes the processes after step 240.

According to the foreign matter biting diagnosis control described above, the ECU 50 calculates the fully closed reference intake pressure PMegr0 (reference intake pressure) according to the acquired (detected) engine rotation speed NE and the detected engine load KL. , The intake pressure increase allowance αΦX according to the detected engine speed NE is calculated, the calculated intake pressure increase allowance αΦX is added to the calculated fully closed reference intake pressure PMegr0, and the addition result (PMegr0 + αΦX) is detected. Based on the corrected intake pressure KPM (intake pressure), it is determined whether or not there is an abnormality due to foreign matter biting (valve opening sticking) of the EGR valve 18.

According to the foreign matter biting diagnostic control described above, the ECU 50 has a foreign matter diameter ΦX (valve seat 32 and valve body 33) of the EGR valve 18 based on the addition result (PMegr0 + αΦX) and the detected corrected intake pressure KPM (intake pressure). The distance between the EGR valve 18 and the foreign matter diameter ΦX of the calculated EGR valve 18 is calculated and set to a predetermined value (for example, "0.9") or more (or "when it becomes larger than approximately 0"). In this case, it is determined that the EGR valve 18 is causing an abnormality due to foreign matter biting (fixing of the valve open), and the calculated foreign matter diameter ΦX of the EGR valve 18 becomes approximately 0 (or). In the case of "less than or equal to a predetermined value"), it is determined that the EGR valve 18 does not cause an abnormality due to foreign matter biting.

According to the foreign matter biting diagnostic control described above, the ECU 50 is bitten between the valve seat 32 and the valve body 33 based on the intake pressure PM detected when the EGR valve 18 is controlled to be fully closed. The diameter of the foreign matter FB is calculated as the foreign matter diameter ΦX (distance between the valve seat 32 and the valve body 33). Here, the ECU 50 corrects the tolerance deviation of the detection value (intake pressure PM) of the intake pressure sensor 51 (intake system detecting means), and then calculates the foreign matter diameter ΦX based on the corrected corrected intake pressure KPM. It has become. That is, the ECU 50 calculates the corrected intake pressure KPM obtained by correcting the detected intake pressure PM based on the product tolerance (including the difference of the detected value) of the intake pressure sensor 51, and uses the calculated corrected intake pressure KPM as the intake pressure. It is designed to be used to calculate the foreign matter diameter ΦX.

According to the foreign matter biting diagnostic control described above, the ECU 50 has a plurality of foreign matter diameters ΦX (separation distance between the valve seat 32 and the valve body 33) in which foreign matter biting (fixation of the valve opening) of the EGR valve 18 is assumed. A plurality of different addition results (PMegr0 + αΦX) different from the calculated fully closed reference intake pressure PMegr0 and the acquired corrected intake pressure are calculated for each of the calculated multiple intake pressure increase allowances αΦX. When it is compared with KPM (intake pressure) and it is determined that the acquired corrected intake pressure KPM is equal to or close to a plurality of addition results (PMegr0 + αΦX) calculated, the intake pressure constituting the addition result (PMegr0 + αΦX) related to the determination. The foreign matter diameter ΦX (opening) corresponding to the rising allowance αΦX is obtained as the foreign matter diameter ΦX (opening) due to the biting of the EGR valve 18.

According to the foreign matter biting diagnosis control described above, the ECU 50 obtains the corrected intake pressure KPM (corrected intake pressure KPM) for the foreign matter diameter ΦX between the plurality of foreign matter diameters ΦX (distance between the valve seat 32 and the valve body 33). The intake pressure) is calculated by interpolating between two adjacent addition results (PMegr0 + αΦX) having close values among a plurality of calculated addition results (PMegr0 + αΦX).

[Correspondence of product tolerance of intake pressure sensor]
Next, how to obtain the corrected intake pressure KPM described above will be described. Before that, the correspondence of the product tolerance (including the tolerance of the detected value) of the intake pressure sensor 51 will be described. FIG. 8 shows an abnormality in the relationship between the foreign matter diameter determined based on the intake pressure PM detected by the intake pressure sensor 51 (when the determination foreign matter diameter = 0.6 (in the case of abnormality determination)) and the engine speed. The judgment result of the central upper and lower limit tolerances of the judgment is shown by a graph. The median upper and lower tolerances mean the upper and lower tolerances with respect to the median. In FIG. 8, the solid line shows the relationship of the tolerance center T0, the broken line shows the relationship of the tolerance upper limit T1, and the alternate long and short dash line shows the relationship of the tolerance lower limit T2. As shown by the solid line in FIG. 8, at the center of tolerance T0, the diameter of the determined foreign matter maintains the same “0.6” and does not shift even if the engine speed changes. When the product tolerance deviation occurs in the intake pressure sensor 51, the determined foreign matter diameter changes as the engine speed changes. That is, as shown by the broken line in FIG. 8, the tolerance upper limit T1 shows a downward-sloping slope in which the diameter of the determined foreign matter becomes smaller as the engine speed decreases, and as shown by the alternate long and short dash line in FIG. 8, the tolerance lower limit T2 Then, it shows an upward-sloping inclination in which the diameter of the determined foreign matter increases as the engine speed decreases. Therefore, in response to this characteristic, in the tolerance upper limit T1 in which the diameter of the determined foreign matter becomes smaller as the engine speed decreases, as shown by arrow Y1 in FIG. 8, in order to bring the diameter of the judged foreign matter closer to the value at the center of the tolerance, It is necessary to correct the detected intake pressure PM to the weight loss side. On the other hand, at the tolerance lower limit T2 where the diameter of the determined foreign matter increases as the engine speed decreases, it is necessary to correct the detected intake pressure PM to the increasing side as shown by the arrow Y2 in FIG.

FIG. 9 shows a normal determination in relation to the foreign matter diameter (when the determination foreign matter diameter = 0 (in the case of normal determination)) determined based on the intake pressure PM detected by the intake pressure sensor 51 and the engine speed. The judgment result of the central upper and lower limit tolerance is shown by a graph. In FIG. 9, the solid line shows the relationship of the tolerance center T10, the broken line shows the relationship of the tolerance upper limit T11, and the alternate long and short dash line shows the relationship of the tolerance lower limit T12. As shown by the solid line in FIG. 9, at the tolerance center T10, the determined foreign matter diameter maintains the same “0.0” and does not shift even if the engine speed changes. When the product tolerance deviation occurs in the intake pressure sensor 51, the determined foreign matter diameter changes as the engine speed changes. That is, as shown by the broken line in FIG. 9, the tolerance upper limit T11 shows a downward-sloping slope in which the diameter of the determined foreign matter becomes smaller as the engine speed decreases, and as shown by the alternate long and short dash line in FIG. 9, the tolerance lower limit T12. Then, it shows an upward-sloping inclination in which the diameter of the determined foreign matter increases as the engine speed decreases. Therefore, in response to this characteristic, in the tolerance upper limit T11 in which the diameter of the determined foreign matter becomes smaller as the engine speed decreases, as shown by arrow Y3 in FIG. 9, in order to bring the diameter of the judged foreign matter closer to the value at the center of the tolerance, It is necessary to correct the detected intake pressure PM to the weight loss side. On the other hand, at the tolerance lower limit T12 where the diameter of the determined foreign matter increases as the engine speed decreases, it is necessary to correct the detected intake pressure PM to the increasing side as shown by the arrow Y4 in FIG.

10 to 13 are graphs showing the relationship between the intake pressure and the intake amount for determining the foreign matter diameter ΦX and the product tolerances of the intake pressure sensor and the air flow meter. FIG. 10 shows a case where the engine speed is low (low speed), FIG. 13 shows a case where the engine speed is high (high speed), and FIG. 11 shows a case where the engine speed is between low speed and high speed. (First intermediate rotation), FIG. 12 shows the second intermediate rotation when the engine rotation speed is between the low rotation and the high rotation and is higher than the first intermediate rotation. In FIGS. 10 to 13, the solid line (thick line) indicates the case where the foreign matter diameter ΦX is “0”, the broken line (thick line) indicates the case where the foreign matter diameter ΦX is substantially “small”, and the alternate long and short dash line (thick line) indicates the foreign matter diameter ΦX. Is generally "large". The broken line between the above lines indicates the diameter between the foreign matter diameters ΦX “large” and “small”, and the diameter between the foreign matter diameters ΦX “small” and “0”. Further, the two solid lines below the foreign matter diameter ΦX “0” indicate the case where the foreign matter diameter ΦX is a “negative value”, respectively. Of the two solid lines, the lower solid line has a larger negative value. In FIGS. 10 to 13, the arrow TG attached to the square indicates the product tolerance of the air flow meter, and similarly, the arrow TP indicates the product tolerance of the intake pressure sensor. In FIGS. 10 to 13, when the intake amount is the same predetermined value G1, the higher the engine speed (from FIG. 10 to FIG. 13), the more the foreign matter diameter ΦX (0, small, large, etc.) corresponds to. It can be seen that the intake pressure to be generated becomes smaller, and the difference between different intake pressures depending on the foreign matter diameter ΦX also becomes smaller. Further, from the solid line in which the foreign matter diameter ΦX becomes a “negative value”, it can be seen that the deviation of the intake pressure increases as the engine speed decreases, and the error of the calculated foreign matter diameter ΦX also increases accordingly.

[Tolerance deviation inclination judgment processing]
Therefore, in this embodiment, in the ECU 50, the product tolerance deviation of the intake pressure sensor 51 is either the upper limit side of the tolerance (inclination downward to the left in FIGS. 8 and 9) or the lower limit side of the tolerance (inclination upward to the left in FIGS. 8 and 9). ) Is designed to be determined. FIG. 14 shows the contents of the tolerance deviation inclination determination process for determining the product tolerance deviation inclination (tolerance deviation inclination) by a flowchart.

When the process shifts to this routine, in step 500, the ECU 50 determines whether or not the foreign matter biting diagnosis is being performed when the engine 1 is decelerated. The ECU 50 can make this determination based on the execution status of the foreign matter biting diagnosis control described above. If the determination result is affirmative, the ECU 50 shifts the process to step 510, and if the determination result is negative, the ECU 50 returns the process to step 500.

In step 510, the ECU 50 takes in the engine speed NE during the foreign matter biting diagnosis during deceleration of the engine 1 and the determined foreign matter diameter ΦX.

Next, in step 520, the ECU 50 determines whether or not the captured engine speed NE is equal to or less than a predetermined value N1. Here, the predetermined value N1 is a determination value on the high rotation side for determining the inclination of the foreign matter diameter ΦX caused by the fluctuation of the engine speed NE due to the tolerance deviation. If the determination result is affirmative, the ECU 50 shifts the process to step 530, and if the determination result is negative, the ECU 50 returns the process to step 500.

In step 530, the ECU 50 determines whether or not the captured engine speed NE is equal to the predetermined value N1. If the determination result is affirmative, the ECU 50 shifts the process to step 540, and if the determination result is negative, the ECU 50 shifts the process to step 560.

In step 540, the ECU 50 takes in the foreign matter diameter ΦX determined when the engine speed NE becomes equal to the predetermined value N1 as the first foreign matter diameter ΦXA.

Next, in step 550, the ECU 50 sets the foreign matter diameter determination flag XNE to "1" assuming that the foreign matter diameter ΦX has been determined, and returns the process to step 500.

On the other hand, in step 560 after shifting from step 530, the ECU 50 determines whether or not the foreign matter diameter determination flag XNE is "1", that is, whether or not the foreign matter diameter ΦX is determined. If the determination result is affirmative, the ECU 50 shifts the process to step 570, and if the determination result is negative, the ECU 50 returns the process to step 500.

Next, in step 570, the ECU 50 determines whether or not the captured engine speed NE is a predetermined value N2 or less. The predetermined value N2 is a value smaller than the predetermined value N1. If the determination result is affirmative, the ECU 50 shifts the process to step 580, and if the determination result is negative, the ECU 50 shifts the process to step 620.

In step 580, the ECU 50 determines whether or not the captured engine speed NE is equal to the predetermined value N2. If the determination result is affirmative, the ECU 50 shifts the process to step 590, and if the determination result is negative, the ECU 50 shifts the process to step 620.

In step 590, the ECU 50 takes in the foreign matter diameter ΦX determined when the engine speed NE becomes equal to the predetermined value N2 as the second foreign matter diameter ΦXB.

Next, in step 600, the ECU 50 calculates the tolerance deviation slope ΔΦX by subtracting the second foreign matter diameter ΦXB from the first foreign matter diameter ΦXA.

Next, in step 610, the ECU 50 sets the update flag XΔΦ to “1” in order to update the correction of the intake pressure PM, and returns the process to step 500.

On the other hand, in step 620 after shifting from step 570 or step 580, the ECU 50 determines whether or not the engine 1 has stopped decelerating or idling. For example, the ECU 50 can determine that the deceleration is stopped based on the throttle opening TA and the idle stop is determined based on the engine speed NE and the throttle opening. If the determination result is affirmative, the ECU 50 shifts the process to step 630, and if the determination result is negative, the ECU 50 returns the process to step 500.

Then, in step 630, the ECU 50 sets the foreign matter diameter determination flag XNE to “0” and returns the process to step 500.

As described above, the ECU 50 calculates the tolerance deviation inclination ΔΦX by the tolerance deviation inclination determination process. In this embodiment, the ECU 50 executes this tolerance deviation inclination determination process every time the engine 1 decelerates. Further, the ECU 50 reflects the obtained tolerance deviation inclination ΔΦX in the calculation of the corrected intake pressure KPM when the engine 1 decelerates next time.

[Calculation of corrected intake pressure]
Next, the calculation of the corrected intake pressure KPM used for the foreign matter biting diagnostic control will be described. FIG. 15 shows the contents of this arithmetic processing by a flowchart.

When the process shifts to this routine, in step 700, the ECU 50 takes in the detected engine speed NE, engine load KL, and intake pressure PM. Further, the ECU 50 takes in the tolerance deviation slope ΔΦX obtained last time.

Next, in step 710, the ECU 50 determines whether or not the update flag XΔΦ is “1”, that is, whether or not the inclination determination of the foreign matter biting diameter is completed in the previous process. If the determination result is affirmative, the ECU 50 shifts the process to step 720, and if the determination result is negative, the ECU 50 returns the process to step 700.

In step 720, the ECU 50 determines whether or not the determined foreign matter diameter ΦX does not change as the engine speed NE decreases. The ECU 50 can make this determination based on the captured tolerance deviation inclination ΔΦX. More specifically, when the tolerance deviation slope is "0", it is determined that the foreign matter diameter ΦX calculated as the engine speed NE decreases does not change. If the determination result is affirmative, the ECU 50 shifts the process to step 730, and if the determination result is negative, the ECU 50 shifts the process to step 770.

Next, in step 730, the ECU 50 calculates the previously obtained correction amount kpm (i-1) as the current correction amount kpm (i). Here, the correction amount kpm (i) is a parameter for correcting the intake pressure PM as described later. The initial value of this correction amount kpm (i) is "0", and the ECU 50 initially sets the correction amount kpm (i) when the power is turned on to the ECU 50, and when the ignition switch is turned off, the correction amount kpm (i) is set. ) Is memorized (learned).

Next, in step 740, the ECU 50 sets the correction amount kpm (i) obtained this time as the final correction amount Kpm.

Next, in step 750, the ECU 50 calculates the corrected intake pressure KPM by adding the final correction amount Kpm obtained this time to the intake pressure PM taken in this time.

After that, in step 760, the ECU 50 sets the update flag XΔΦ to “0” and returns the process to step 700.

On the other hand, in step 770 after shifting from step 720, the ECU 50 determines whether or not the determined foreign matter diameter ΦX is reduced as the engine speed NE decreases. The ECU 50 can make this determination based on the captured tolerance deviation inclination ΔΦX. If the determination result is affirmative, the ECU 50 shifts the process to step 780 assuming that the foreign matter diameter ΦX has been reduced, and if the determination result is negative, the processing is performed as if the foreign matter diameter ΦX has been expanded in step 790. Move to.

In step 780, the ECU 50 updates the current correction amount kpm (i) by subtracting the predetermined value β from the previous correction amount kpm (i-1). After that, the ECU 50 executes the processes of steps 740 to 760.

On the other hand, in step 790, the ECU 50 updates the current correction amount kpm (i) by adding a predetermined value β to the previous correction amount kpm (i-1). After that, the ECU 50 executes the processes of steps 740 to 760.

As described above, the ECU 50 obtains the corrected intake pressure KPM by correcting the detected intake pressure PM with the final correction amount Kpm by this calculation process. Here, the ECU 50 adds or subtracts a predetermined value β from the previous correction amount kpm (i-1) as the tolerance deviation slope ΔΦX increases, and completes the correction of the corrected intake pressure KPM at an early stage. be able to.

According to the above-mentioned "tolerance deviation inclination determination process" and "calculation of corrected intake pressure", the ECU 50 changes the foreign matter diameter ΦX when the calculated foreign matter diameter ΦX fluctuates with the change of the engine speed NE. The intake pressure PM detected so that is eliminated is corrected.

[About the action and effect of the engine system]
According to the configuration of the engine system of the first embodiment described above, the intake pressure PM detected when the EGR valve 18 is controlled to be fully closed is the detection value of the intake pressure sensor 51 (intake system detecting means). After correcting the tolerance deviation of a certain intake pressure PM, the foreign matter diameter ΦX (distance distance between the valve seat 32 and the valve body 33) is calculated based on the corrected intake pressure KPM. Therefore, the variation in the calculation result of the foreign matter diameter ΦX (separation distance) is reduced due to the foreign matter biting of the EGR valve 18. Therefore, regardless of whether or not there is a tolerance deviation in the detection values of the intake pressure sensor 51 (intake system detecting means), the foreign matter diameter ΦX (distance between the valve seat 32 and the valve body 33) due to the foreign matter being caught in the EGR valve 18. ) Can be obtained with high accuracy. As a result, it is possible to diagnose an abnormality due to foreign matter biting (valve opening sticking) with high accuracy.

According to the configuration of this embodiment, even if the calculated foreign matter diameter ΦX (separation distance) fluctuates with the change of the engine speed NE, the intake pressure PM detected so that the fluctuation disappears is corrected. .. Therefore, even if the engine speed NE changes, the variation in the calculation result of the foreign matter diameter ΦX (separation distance) is small due to the foreign matter biting of the EGR valve 18. Therefore, the foreign matter diameter ΦX (separation distance) can be obtained with higher accuracy regardless of the change in the engine speed NE.

<Second Embodiment>
Next, a second embodiment in which the engine system is embodied in a gasoline engine system will be described in detail with reference to the drawings.

In the following description, the components equivalent to those in the first embodiment will be described by adding the same reference numerals, omitting the description, and focusing on the different points. In this embodiment, the following controls are executed on the premise of the control of the first embodiment.

[Calculation of final foreign matter diameter]
This embodiment differs from the first embodiment in that the final foreign matter diameter ΦK is calculated for the foreign matter diameter ΦX bitten by the EGR valve 18. FIG. 16 shows the calculation contents of the final foreign matter diameter ΦK by a flowchart.

When the process shifts to this routine, in step 800, the ECU 50 determines whether the operation of the engine 1 is decelerated or idle. The ECU 50 can make this determination based on, for example, the throttle opening TA and the engine speed NE. If the determination result is affirmative, the ECU 50 shifts the process to step 810, and if the determination result is negative, the ECU 50 returns the process to step 800.

In step 810, the ECU 50 determines whether or not the EGR valve 18 has a foreign matter biting abnormality. The ECU 50 makes this determination based on the result of the foreign matter biting diagnostic control (see FIGS. 4 and 5) described above. If the determination result is affirmative, the ECU 50 shifts the process to step 820, and if the determination result is negative, the ECU 50 returns the process to step 800.

In step 820, the ECU 50 takes in the foreign matter diameter ΦX calculated by the foreign matter biting diagnosis control.

Next, in step 830, the ECU 50 obtains the opening degree KegrST corresponding to the foreign matter diameter of the EGR valve 18 corresponding to the foreign matter diameter ΦX. For example, the ECU 50 can obtain the foreign matter diameter equivalent opening degree KegrST corresponding to the foreign matter diameter ΦX by referring to the foreign matter diameter equivalent opening degree map as shown in FIG. As shown in FIG. 17, the foreign matter diameter corresponding opening KegrST has a proportional relationship with the foreign matter diameter ΦX.

Next, in step 840, the ECU 50 determines whether or not the engine 1 has a deceleration fuel cut, that is, whether or not the fuel injection from the injector 25 is interrupted during deceleration. If the determination result is negative (fuel is not cut during deceleration), the ECU 50 shifts the process to step 850, and if the determination result is affirmative, returns the process to step 800.

In step 850, the ECU 50 controls the EGR valve 18 to the determined foreign matter diameter equivalent opening degree KegrST.

Next, in step 860, the ECU 50 determines whether or not the detected intake pressure PM has increased. The ECU 50 can determine the direction of change in the intake pressure PM by comparing the intake pressure PM detected last time with the intake pressure PM detected this time. If the determination result is affirmative, the ECU 50 shifts the process to step 870, and if the determination result is negative, the ECU 50 shifts the process to 950.

In step 870, the ECU 50 calculates the control opening degree TegrST (i) by subtracting a predetermined value γ from the foreign matter diameter equivalent opening degree KegrST.

Next, in step 880, the ECU 50 controls the EGR valve 18 to close the EGR valve 18 to the calculated control opening degree TegrST (i).

Next, in step 890, the ECU 50 determines whether or not the detected intake pressure PM has dropped. If the determination result is affirmative, the ECU 50 shifts the process to step 900, and if the determination result is negative, the ECU 50 shifts the process to step 1000.

In step 900, the ECU 50 calculates the control opening degree TegrST (i) by subtracting the predetermined value γ from the previous control opening degree TegrST (i-1).

Next, in step 910, the ECU 50 further controls the EGR valve 18 to close the EGR valve 18 to the calculated control opening degree TegrST (i).

Next, in step 920, the ECU 50 determines whether or not the opening degree obtained by subtracting the predetermined value δ from the foreign matter diameter equivalent opening degree KegrST is larger than the control opening degree TegrST (i) calculated in step 900. If the determination result is affirmative, the ECU 50 shifts the process to step 930, and if the determination result is negative, returns the process to 890.

In step 930, the ECU 50 controls the EGR valve 18 to be fully closed. Further, in step 940, the ECU 50 sets the final foreign matter diameter ΦK to “0” (calculated as “0”) because the EGR valve 18 is fully closed, and returns the process to step 800.

On the other hand, in step 950 after shifting from step 860, the ECU 50 calculates the control opening TegrST (i) by adding a predetermined value γ to the foreign matter diameter equivalent opening KegrST.

Next, in step 960, the ECU 50 controls the EGR valve 18 to open the EGR valve 18 to the calculated control opening degree TegrST (i).

Next, in step 970, the ECU 50 determines whether or not the detected intake pressure PM has increased. If the determination result is negative, the ECU 50 shifts the process to step 980, and if the determination result is affirmative, the ECU 50 shifts the process to 1000.

In step 980, the ECU 50 calculates the current control opening degree TegrST (i) by adding a predetermined value γ to the previous control opening degree TegrST (i-1).

Next, in step 990, the ECU 50 further controls the EGR valve 18 to open the EGR valve 18 to the calculated control opening degree TegrST (i), and returns the process to step 970.

On the other hand, in step 1000 after shifting from step 890 or step 970, the ECU 50 obtains the final foreign matter diameter ΦK from the control opening degree TegrST (i) calculated this time. The ECU 50 can obtain the final foreign matter diameter ΦK according to the control opening degree TegrST (i) by referring to a predetermined final foreign matter diameter map (not shown). After that, the ECU 50 returns the process to step 800.

According to the calculation of the final foreign matter diameter ΦK described above, the ECU 50 opens the EGR valve 18 to the opening degree corresponding to the calculated foreign matter diameter ΦX (the opening degree equivalent to the foreign matter diameter KegrST), and the detected intake pressure PM The opening degree of the EGR valve 18 (control opening degree TegrST (i)) is increased until the detected intake pressure PM changes, and the opening degree when the detected intake pressure PM changes. The foreign matter diameter ΦX is corrected by setting the diameter corresponding to (control opening degree TegrST (i)) as the foreign matter diameter (final foreign matter diameter ΦK).

Further, according to the calculation of the final foreign matter diameter ΦK described above, the ECU 50 opens the EGR valve 18 to the opening degree corresponding to the calculated foreign matter diameter ΦX (foreign matter diameter equivalent opening KegrST), and the detected intake air is detected. When the pressure PM changes, the opening degree of the EGR valve 18 (control opening degree TegrST (i)) is reduced until the detected intake pressure PM does not change, and the detected intake pressure PM does not change. The foreign matter diameter ΦX is corrected by setting the diameter corresponding to the opening degree (control opening degree TegrST (i)) as the foreign matter diameter (final foreign matter diameter ΦK).

[About the action and effect of the engine system]
According to the configuration of the engine system of the second embodiment described above, the following actions and effects can be obtained in addition to the actions and effects of the first embodiment. That is, in this embodiment, since the calculation of the final foreign matter diameter ΦK (separation distance) as described above is executed, even if there is an error in the calculated foreign matter diameter ΦX, a more appropriate foreign matter diameter that eliminates the error is eliminated. (Final foreign matter diameter ΦK) is calculated. Therefore, regardless of the calculated error of the foreign matter diameter ΦX (separation distance), the calculation accuracy of the foreign matter diameter (final foreign matter diameter ΦK) can be further improved.

<Third Embodiment>
Next, a third embodiment in which the engine system is embodied in a gasoline engine system will be described in detail with reference to the drawings.

In this embodiment, the following controls are executed on the premise of the control of the first embodiment or the control of the second embodiment. In this embodiment, the ECU 50 also corresponds to an example of the engine stall avoidance processing means for avoiding the engine stall in the disclosure technique.

[About idle-up control during deceleration]
In this embodiment, the idle-up control during deceleration executed in connection with the above-mentioned foreign matter biting diagnostic control (see FIGS. 4 and 5) will be described. FIG. 18 shows an example of the control content by a flowchart. If the EGR valve 18, which should have been controlled to be fully closed when the engine 1 is decelerated, is not completely closed due to the biting of foreign matter FB, etc., the EGR gas leaks to the engine 1 and causes the engine 1 to misfire or stall. May occur. Therefore, in this embodiment, when it is determined that the EGR valve 18 is bitten by the foreign matter FB, the idle-up control during deceleration is executed in order to avoid the engine stall.

When the process shifts to this routine, in step 1100, the ECU 50 determines whether the operation of the engine 1 is decelerated or idle. If the determination result is affirmative, the ECU 50 shifts the process to step 1110, and if the determination result is negative, the ECU 50 returns the process to step 1100.

In step 1110, the ECU 50 determines whether or not the EGR valve 18 is caught in foreign matter. The ECU 50 can make this determination based on the result of the foreign matter biting diagnostic control (see FIGS. 4 and 5) described above. If the determination result is affirmative, the ECU 50 shifts the process to step 1120, and if the determination result is negative, the ECU 50 shifts the process to step 1240.

In step 1120, the ECU 50 takes in the detected engine speed NE and the foreign matter diameter ΦX (or the final foreign matter diameter ΦK) determined by the foreign matter biting diagnosis control. This foreign matter diameter ΦX (or final foreign matter diameter ΦK) is determined after correcting the detection error of the intake pressure PM due to the product tolerance of the intake pressure sensor 51 in the above-mentioned foreign matter biting diagnostic control (see FIGS. 4 and 5). It is a thing.

Next, in step 1130, the ECU 50 determines whether or not the update flag XΔΦ is “0”, that is, whether or not the correction of the intake pressure PM has been completed in the previous process. When the determination result is affirmative (correction not completed), the ECU 50 shifts the process to step 1140, and when the determination result is negative (correction completed), the ECU 50 shifts the process to step 1150.

In step 1140, the ECU 50 calculates the target idle speed TidNE according to the engine speed NE and the foreign matter diameter ΦX (or the final foreign matter diameter ΦK). That is, the ECU 50 sets the target idle rotation speed TidNE by adding the first idle-up rotation speed KeuNE1 according to the foreign matter diameter ΦX (or the final foreign matter diameter ΦK) to the predetermined basic idle rotation speed KidNE (fixed value). Ask. Here, the ECU 50 can obtain the first idle-up rotation speed KeuNE1 according to the engine rotation speed NE and the foreign matter diameter ΦX by referring to the first idle-up rotation speed map as shown in FIG. 19, for example. .. In FIG. 19, the broken line shows the data when the engine speed NE is low (low speed), the one-point chain line shows the data when the engine speed NE is high (high speed), and the solid line shows the low speed and the high speed. The data in the case of the intermediate rotation between are shown. In this map, basically, the first idle-up rotation speed KeuNE1 is set to increase as the foreign matter diameter ΦX increases to a certain upper limit value. Further, in this map, the first idle-up rotation speed KeuNE1 is set to increase as the engine speed NE increases. In this map, the intermediate data between the three data shown in FIG. 19 can be obtained by interpolation calculation with the engine speed NE.

On the other hand, in step 1150, the ECU 50 calculates the target idle speed TidNE according to the engine speed NE and the foreign matter diameter ΦX (or the final foreign matter diameter ΦK). That is, the ECU 50 has different characteristics from the second idle-up rotation speed KeuNE2 (first idle-up rotation speed KeuNE1) according to the foreign matter diameter ΦX (or the final foreign matter diameter ΦK) with respect to the predetermined basic idle rotation speed KidNE (fixed value). ) Is added to obtain the target idle speed TidNE. Here, the ECU 50 can obtain the second idle-up rotation speed KeuNE2 according to the engine rotation speed NE and the foreign matter diameter ΦX by referring to the second idle-up rotation speed map as shown in FIG. 20, for example. .. In FIG. 20, the broken line shows the data when the engine speed NE is low (low speed), the one-point chain line shows the data when the engine speed NE is high (high speed), and the solid line shows low speed and high speed. The data in the case of the intermediate rotation between are shown. Also in this map, basically, the second idle-up rotation speed KeuNE2 is set to increase as the foreign matter diameter ΦX increases to a certain upper limit value. Further, in this map, the second idle-up rotation speed KeuNE2 is set to increase as the engine speed NE increases. This second idle-up rotation speed map is different from the first idle-up rotation speed map in that the second idle-up rotation speed KeuNE2 is "0" in the range of "0 to X1" where the foreign matter diameter ΦX is relatively small. That is. That is, when the correction of the intake pressure PM is completed (when the correction intake pressure KPM is used), the determination error of the foreign matter diameter ΦX is reduced, so that the foreign matter diameter ΦX is idled up in a relatively small range. It is designed so that it does not control. Also in this map, the intermediate data between the three data shown in FIG. 20 can be obtained by performing interpolation calculation with the engine speed NE.

Moving from step 1140 or step 1150, in step 1160, the ECU 50 determines whether the engine 1 has a deceleration fuel cut. If the determination result is negative (in the case of deceleration without fuel cut), the ECU 50 shifts the process to step 1170, and if the determination result is affirmative, shifts the process to step 1240.

In step 1170, idle-up control is executed based on the calculated target idle speed TidNE. That is, the ECU 50 feedback-controls the electronic throttle device 14 so that the engine speed NE becomes the target idle speed TidNE.

Next, in step 1180, the ECU 50 takes in the detected engine speed NE.

Next, in step 1190, the ECU 50 determines whether or not the captured engine speed NE is higher than the target idle speed TidNE. If the determination result is affirmative, the ECU 50 shifts the process to step 1200, and if the determination result is negative, the ECU 50 shifts the process to step 1220.

In step 1200, the ECU 50 calculates the difference between the target idle speed TidNE and the actual engine speed NE as the speed difference ΔNE. In this case, the rotation speed difference ΔNE is a positive value.

Next, in step 1210, the ECU 50 controls the valve closing of the electronic throttle device 14 according to the rotation speed difference ΔNE. That is, the ECU 50 controls the valve closing of the electronic throttle device 14 in order to reduce the engine speed NE toward the target idle speed TidNE. After that, the ECU 50 returns the process to step 1100.

On the other hand, in step 1220, the ECU 50 calculates the difference between the target idle speed TidNE and the actual engine speed NE as the speed difference −ΔNE. In this case, the rotation speed difference −ΔNE becomes a negative value.

Next, in step 1230, the ECU 50 controls the valve opening of the electronic throttle device 14 according to the rotation speed difference −ΔNE. That is, the ECU 50 controls the opening of the electronic throttle device 14 in order to increase the engine speed NE toward the target idle speed TidNE. After that, the ECU 50 returns the process to step 1100.

On the other hand, in step 1240 after shifting from step 1110 or step 1160, the ECU 50 obtains the basic idle rotation speed KidNE as the target idle rotation speed TidNE, and returns the process to step 1100. Since this target idle speed TidNE does not include the idle-up speed KeuNE, it is lower than the target idle speed TidNE without fuel cut, and is a value that does not contribute to idle-up, that is, cancels idle-up. It becomes a value.

According to the above-mentioned idle-up control during deceleration, when the foreign matter diameter ΦX (or the final foreign matter diameter ΦK) is calculated, the ECU 50 sets the target idle speed TidNE to a set value larger than the predetermined basic idle speed KidNE. An electronic throttle device that is set, corrects the set target idle speed TidNE according to the current engine speed NE of the engine 1, and makes the detected engine speed NE the corrected target idle speed TidNE. It is designed to control 14.

Here, FIG. 21 shows an example of the behavior of various parameters by the idle-up control by a time chart. In FIG. 21, (a) shows a change in engine speed NE (solid line) and a change in foreign matter diameter determination D / ΦX (broken line), and (b) shows a change in target idle speed TidNE.

In FIG. 21, when the engine 1 starts decelerating (without fuel cut) at time t0 and the engine speed NE starts to decrease as shown by the solid line in (a), at time t1, a broken line is shown in (a). As shown, the foreign matter diameter determination D / ΦX is performed, and it is determined that the foreign matter biting abnormality is performed. At this time, the target idle rotation speed TidNE increases from the basic idle rotation speed KidNE by the amount of the first idle-up rotation speed KeuNE1 (or the second idle-up rotation speed KeuNE2).

After that, when the engine speed NE decreases to a predetermined value as shown by the solid line in (a) from time t1 to time t2, the target idle speed TidNE also decreases to a predetermined value as shown in (b). .. In this way, when the foreign matter diameter ΦX (or the final foreign matter diameter ΦK) is determined (calculated) by the EGR valve 18, the engine 1 has the first idle-up rotation speed KeuNE1 (or the second idle) rather than the basic idle speed KidNE. It is controlled to a target idle speed TidNE that is higher by the amount of the up speed KeuNE2), and it is possible to suppress misfire and engine stall of the engine 1 due to the inflow of EGR gas.

[About the action and effect of the engine system]
According to the configuration of the third embodiment described above, the following actions and effects can be obtained in addition to the actions and effects of the first embodiment or the second embodiment. That is, in this embodiment, since the idle-up control during deceleration as described above is executed, the detected engine speed is detected even if there is an error in the calculated foreign matter diameter ΦX or the final foreign matter diameter ΦK (separation distance). The electronic throttle device 14 is controlled so that the NE is the corrected target idle speed TidNE, and the engine stall is avoided. Therefore, regardless of the calculated error of the foreign matter diameter ΦX or the final foreign matter diameter ΦK (separation distance), the engine stall due to unnecessary reflux of the EGR gas can be appropriately avoided. Further, it is possible to achieve both avoidance of engine stall and suppression of deterioration of deceleration of the engine 1.

It should be noted that this disclosure technique is not limited to each of the above-described embodiments, and a part of the configuration may be appropriately modified and implemented within a range that does not deviate from the purpose of the disclosure technique.

(1) In each of the above-described embodiments, the tolerance deviation of the detection value (intake pressure PM) of the intake pressure sensor 51 as the intake system detection means is corrected. Here, it is conceivable that the tolerance deviation of the determination result of the foreign matter diameter ΦX is deviated by the combination of the product tolerance of the intake pressure sensor 51 and the product tolerance of the air flow meter 54. That is, the upper limit of the determination result (deviation to the larger side) is determined by the combination of the upper limit of the product tolerance of the intake pressure sensor 51 and the lower limit of the product tolerance of the air flow meter 54. On the other hand, the lower limit of the determination result (deviation to the smaller side) is determined by the combination of the lower limit of the product tolerance of the intake pressure sensor 51 and the upper limit of the product tolerance of the air flow meter 54. Therefore, instead of correcting only the tolerance deviation of the detection value (intake pressure PM) of the intake pressure sensor 51, the tolerance deviation of the detection value (intake amount Ga) of the air flow meter 54 as the intake system detection means is similarly corrected. It is also possible to correct both the tolerance deviation of the detected value of the intake pressure sensor 51 and the tolerance deviation of the detected value of the air flow meter 54.

(2) In each of the above embodiments, the fully closed reference intake pressure PMegr0 is calculated according to the acquired engine speed NE and the acquired engine load KL by referring to a predetermined fully closed reference intake pressure map. However, it is also possible to calculate the fully closed reference intake pressure according to the acquired engine speed and the acquired engine load by referring to the predetermined fully closed reference function formula.
(3) In each of the above embodiments, the intake pressure increase allowance αΦX corresponding to the acquired engine speed NE is obtained by referring to the predetermined intake pressure increase allowance map, but the predetermined intake pressure increase allowance is obtained. By referring to the function formula, it is also possible to obtain the intake pressure increase allowance according to the acquired engine speed.

(4) In each of the above embodiments, the EGR device 10 of the engine is embodied as a so-called "high pressure loop type" EGR device 10 in a gasoline engine system without a supercharger, but gasoline with a supercharger is provided. It can also be embodied in a so-called "high pressure loop type" or "low pressure loop type" EGR device in an engine system.

(5) In each of the above embodiments, the EGR device 10 of the engine is applied to the gasoline engine system, but this EGR device can also be applied to the diesel engine system. In this case, even if an abnormality due to foreign matter biting into the EGR valve (an abnormality due to valve opening sticking) is determined, idle-up control for avoiding engine stall or the like can be omitted.

(6) In each of the above embodiments, the foreign matter diameter ΦX (X = -0.6, -0.3, 0.3, 0.3, 0.6, 0.9) of the foreign matter FB bitten by the EGR valve 18. And the intake pressure increase allowance αΦX (X = -0.6, -0.3, 0, 0.3, 0.6, 0.9) according to the engine speed NE is calculated. On the other hand, more detailed foreign matter diameter ΦX (X = -0.6, -0.4, -0.2, 0, 0.2, 0.4, 0.6, 0.8, 1.0) And the intake pressure increase allowance αΦX (X = -0.6, -0.4, -0.2, 0, 0.2, 0.4, 0.6, 0.8, 1 according to the engine speed NE It is configured to obtain .0), or a more rough foreign matter diameter ΦX (X = -0.4,0,0.4,0.8) and intake pressure increase allowance αΦX (X) according to the engine speed NE. = −0.4,0,0.4,0.8) can also be obtained.

(7) In each of the above embodiments, an abnormality due to foreign matter biting of the EGR valve 18 is assumed, but the abnormality is not limited to the abnormality due to foreign matter biting, and an abnormality due to valve opening sticking that does not fully close with the valve open for other reasons You can also assume.

(8) In each of the above embodiments, the ECU 50 determines that the EGR valve 18 does not cause an abnormality due to foreign matter biting when the calculated opening degree of the EGR valve 18 becomes "approximately 0 or less". , The condition of "less than or equal to a predetermined value" can be applied instead of the condition of "less than or equal to 0".

(9) In each of the above-described embodiments, the separation distance between the valve seat 32 and the valve body 33 of the EGR valve 18 is calculated based on the corrected intake pressure KPM, but instead of this, the corrected intake pressure KPM is calculated. It can also be configured to calculate the opening area between the valve seat and the valve body based on.

(10) In the second embodiment, the "tolerance deviation inclination determination process" shown in FIG. 14 and the "calculation of the corrected intake pressure" shown in FIG. 15 are executed, and the obtained corrected intake pressure KPM is shown in FIGS. 4 and 4. It is configured to be reflected in the "foreign matter biting diagnosis control" shown in 5, but it is not limited to this, as long as it is a control that calculates the separation distance or opening area between the valve seat and the valve body using the intake pressure. The control can also be configured to reflect the corrected intake pressure KPM. In this case as well, the foreign matter diameter can be obtained with high accuracy by the corrected intake pressure KPM.

This disclosed technique can be applied to a gasoline engine system or a diesel engine system equipped with an EGR device.

1 Engine 3 Intake passage 3a Surge tank 5 Exhaust passage 10 EGR device 14 Electronic throttle device (intake amount control valve)
17 EGR passage 18 EGR valve 32 Valve seat 33 Valve body 50 ECU (control means, calculation means, engine stall avoidance processing means)
51 Intake pressure sensor (operating state detecting means, intake system detecting means)
52 Rotation speed sensor (operating state detecting means, rotation detecting means)
54 Air flow meter (operating state detecting means, intake system detecting means)

Claims (5)

With the engine
An intake passage for introducing intake air into the engine and
An exhaust passage for deriving exhaust from the engine and
An EGR passage for flowing a part of the exhaust gas discharged from the engine to the exhaust passage as EGR gas to the intake passage and returning it to the engine, and an EGR valve for adjusting the flow rate of the EGR gas in the EGR passage. EGR device including and
The EGR valve includes a valve seat and a valve body that can be seated on the valve seat.
An operating state detecting means for detecting the operating state of the engine and
The operating state detecting means includes an intake system detecting means for detecting the pressure or flow rate of the intake air introduced into the engine in the intake passage.
A control means for controlling at least the EGR valve based on the detected operating state, and
It is provided with a calculation means for calculating the separation distance or opening area between the valve seat and the valve body based on the detected intake pressure or flow rate when the EGR valve is controlled to be fully closed. In the engine system
The calculation means is an engine system characterized in that the separation distance or the opening area is calculated after correcting the tolerance deviation of the detection values of the intake system detection means. In the engine system according to claim 1,
When the calculated separation distance or the opening area fluctuates with a change in the engine speed, the calculation means detects the intake so that the fluctuation of the separation distance or the opening area disappears. An engine system characterized by compensating for pressure or flow. In the engine system according to claim 1 or 2.
The calculation means is detected when the EGR valve is opened to the calculated separation distance or the opening corresponding to the opening area, and the detected intake pressure or flow rate does not change. It is characterized in that the opening degree of the EGR valve is increased until the pressure or flow rate of the intake air changes, and the opening degree when the detected pressure or flow rate of the intake air changes is corrected as the separation distance or the opening area. Engine system. In the engine system according to any one of claims 1 to 3.
The calculation means opens the EGR valve to the calculated separation distance or an opening corresponding to the opening area, and the intake is detected when the pressure or flow rate of the detected intake changes. The opening degree of the EGR valve is reduced until the pressure or flow rate of the EGR valve does not change, and the opening degree when the detected intake pressure or flow rate does not change is corrected as the separation distance or the opening area. The characteristic engine system. In the engine system according to any one of claims 1 to 4.
Further provided with an intake amount adjusting valve arranged in the intake passage and for adjusting the intake amount flowing through the intake passage, and an engine stall avoidance processing means for avoiding the engine stall.
The operating state detecting means further includes a rotation speed detecting means for detecting the rotation speed of the engine.
The engine stall avoidance processing means sets a target idle rotation speed to a set value larger than a predetermined basic idle rotation speed when the separation distance or the opening area is calculated by the calculation means, and the target is set. The feature is that the idle speed is corrected according to the current speed of the engine, and the intake air amount control valve is controlled so that the detected speed of the engine becomes the corrected target idle speed. Engine system to do.

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