JP2010106787A - Controller for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for an internal combustion engine capable of determining an operating state of a waste gate valve irrespective of an operating condition of a turbocharger. <P>SOLUTION: In one cycle of the internal combustion engine 10, exhaust pulsation having a cycle every 360°CA is generated by explosion strokes of #2 and #3 cylinders in one exhaust passage 18 connected to a twin entry type turbocharger (Fig.2(a), thin line). Sine an internal pressure of the exhaust passage 18 is influenced by the explosion strokes of the #2 and #3 cylinders at valve closing with respect to indicating peak characteristics every 360°CA at valve opening of the waste gate valve 30, the peak characteristics are indicated every 180°CA (Fig.2(a), wide line). Determination of the operating state of the waste gate valve 30 is carried out by acquiring the peak characteristics by a pressure sensor 32 disposed in an exhaust passage 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine with a turbocharger having a plurality of turbine inlets.

  Conventionally, for example, Patent Document 1 discloses an internal combustion engine with a supercharger in which a turbine scroll portion is configured by two exhaust passages, and a failure of a control valve arranged in a part of the exhaust passages is detected. Yes. This control valve is provided for the purpose of communicating / blocking the two exhaust passages, and is controlled according to the open / close area of the map, but if a failure occurs, a desired amount of exhaust gas is supplied to the turbocharger. Can not do it. For example, if the map is in a closed region but the control valve is in an open state, the degree of increase in supercharging pressure is lower than that in a normal state. Therefore, the decrease in the supercharging pressure is grasped by comparison with a predetermined set supercharging pressure. By doing so, it is possible to detect a failure of the control valve.

JP 2003-328765 A JP 2006-207509 A JP 2006-348894 A

  Some exhaust passages of an internal combustion engine with a turbocharger are provided with a waste gate valve for bypassing the turbine to a part of the exhaust gas in order to prevent overcharging. By opening and closing the waste gate valve, it becomes possible to improve fuel efficiency by reducing back pressure and increase exhaust temperature by bypass. For this reason, it is desirable for the waste gate valve to be able to detect the failure by judging the operation state, similarly to the control valve of Patent Document 1.

  However, the control valve of Patent Document 1 detects a failure by detecting a decrease in the degree of increase in supercharging pressure. This means that a failure can only be detected in a region where the boost pressure increases. Therefore, with the control valve of Patent Document 1, it is not always possible to determine the operating state of the waste gate valve in all operating situations of the turbocharger.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a control device for an internal combustion engine that can determine the operating state of a waste gate valve regardless of the operating state of the turbocharger. And

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
A turbocharger having a turbine with a plurality of inlets;
A plurality of upstream exhaust passages arranged upstream of the turbocharger and communicating the plurality of inlets with a cylinder group of an internal combustion engine;
A downstream exhaust passage disposed downstream of the turbocharger;
A plurality of bypass passages that connect the plurality of upstream exhaust passages and the downstream exhaust passage without passing through the turbine;
A wastegate valve capable of opening and closing the plurality of bypass passages;
Exhaust pressure acquisition means for acquiring exhaust pressure in at least one exhaust passage of the plurality of upstream exhaust passages and / or in the downstream exhaust passage;
Operating state determining means for determining an operating state of the waste gate valve based on the exhaust pressure.

The second invention is the first invention, wherein
Command information obtaining means for obtaining opening / closing command information of the waste gate valve;
Failure diagnosis means for diagnosing a failure of the waste gate valve based on the waveform information of the exhaust pressure and the opening / closing command information is provided.

The third invention is the second invention, wherein
The waveform information is a frequency of exhaust pulsation in the at least one exhaust passage,
The failure diagnosis means comprises frequency comparison means for comparing the exhaust pulsation frequency with a theoretical frequency corresponding to the opening / closing command information.

Moreover, 4th invention is set in 3rd invention,
The frequency comparison means comprises peak number comparison means for comparing the peak number of exhaust pulsation per cycle of the internal combustion engine with the theoretical peak number of exhaust pulsation,
The theoretical peak number of exhaust pulsation corresponds to the total number of cylinders included in the cylinder group when the waste gate valve is opened, and the total number of cylinders included in the cylinder group when the waste gate valve is closed. It corresponds to the number divided by the number of the plurality of entrances.

The fifth invention is the second invention, wherein
The waveform information is an amplitude of exhaust pulsation in the downstream exhaust passage.

  According to the first invention, the operation of the waste gate valve based on the exhaust pressure in at least one of the plurality of exhaust passages upstream of the turbocharger and / or in the exhaust passage downstream of the turbocharger. The state can be determined. The exhaust pressure can be acquired regardless of the operation status of the turbocharger. Therefore, it is possible to determine the operating state of the waste gate valve regardless of the operating state of the turbocharger.

  According to the second invention, the waste gate valve opening / closing command information can be acquired, and the failure diagnosis of the waste gate valve can be performed from the waveform information of the exhaust pressure and the opening / closing command information. The open / close command information can be acquired regardless of the operation status of the turbocharger, similar to the waveform information of the exhaust pressure. Therefore, the failure diagnosis of the waste gate valve can be performed regardless of the operation status of the turbocharger.

  According to the third aspect, it is possible to compare the frequency of exhaust pulsation upstream of the turbocharger with the theoretical frequency corresponding to the opening / closing command information. The frequency of exhaust pulsation is an index indicating the actual operation of the waste gate valve, and the theoretical frequency is an index indicating the theoretical operation of the waste gate valve. For this reason, the waste gate valve failure diagnosis can be reliably performed by comparing the two indexes.

  The theoretical peak number of exhaust pulsation corresponds to the total number of cylinders included in the cylinder group of the internal combustion engine when the wastegate valve is opened, and the total number of cylinders included in this cylinder group is the number of turbine inlets when the valve is closed. Corresponds to the number divided. Therefore, according to the fourth aspect of the invention, the failure diagnosis of the waste gate valve can be reliably performed by comparing the numbers of both peaks.

  According to the fifth aspect of the invention, the failure diagnosis of the waste gate valve can be reliably performed based on the amplitude of the exhaust pulsation downstream of the turbocharger.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
[Description of System Configuration of Embodiment 1]
First, a system configuration according to the first embodiment will be described with reference to FIG. The system according to the first embodiment includes an internal combustion engine 10. The internal combustion engine 10 is used as a power source of a vehicle, for example. The internal combustion engine 10 is an in-line four-cylinder internal combustion engine having first to fourth cylinders, and the numbers of the respective cylinders are denoted as # 1 to # 4. In the internal combustion engine 10, it is assumed that the explosion stroke is performed in the order of # 1 → # 2 → # 4 → # 3 while the crankshaft rotates twice (= 720 ° CA).

  The exhaust ports of the # 1 and # 4 cylinders of the internal combustion engine 10 communicate with a common exhaust manifold 12. Further, the exhaust ports of the # 2 and # 3 cylinders of the internal combustion engine 10 communicate with a common exhaust manifold 14. These two exhaust manifolds 12 and 14 are connected to two exhaust inlets of the turbocharger 20 via two exhaust passages 16 and 18 arranged in parallel. The turbocharger 20 is a twin-entry turbocharger and includes a turbine having two exhaust inlets. An exhaust passage 22 is connected to the downstream outlet of the turbocharger 20. A catalyst 28 for purifying the exhaust gas is disposed in the exhaust passage 22.

  In the exhaust passages 16 and 18, bypass passages 24 and 26 for flowing the exhaust to the exhaust passage 22 while avoiding the turbocharger 20 are arranged, respectively. In addition, in the bypass passages 24 and 26, a waste gate valve 30 capable of opening / closing control is disposed. The waste gate valve 30 is configured so as to be in communication with or disconnected from the exhaust passages 16 and 18 and the exhaust passage 22 simultaneously by being controlled to open and close. The waste gate valve 30 is provided for the purpose of preventing excessive supercharging of exhaust gas to the turbocharger 20 and achieving early warm-up of the catalyst 28 at the time of starting.

  A pressure sensor 32 is disposed in the exhaust passage 18 upstream of the turbocharger 20. The pressure sensor 32 is configured to generate an output according to the internal pressure of the exhaust passage 18. The pressure sensor 32 may be disposed in the exhaust passage 16 upstream of the turbocharger 20.

  The system of the present embodiment further includes an ECU (Electronic Control Unit) 50. The ECU 50 is connected to the above-described sensors, actuators, and the like. The ECU 50 is configured to control the opening degree and the like of the waste gate valve 30 based on the outputs of these sensors.

  FIG. 2 is a diagram for explaining exhaust pulsation upstream of the turbine. The horizontal axis in FIG. 2 represents the crank angle (CA), and 720 ° CA corresponds to one cycle of the internal combustion engine 10. Also, the two waveforms shown in FIG. 2A indicate exhaust pulsations derived from the # 2 and # 3 cylinders, that is, changes in the internal pressure of the exhaust passage 18 acquired by the pressure sensor 32. In addition, the two waveforms shown in FIG. 2B indicate that the exhaust pulsation derived from the # 1 and # 4 cylinders indicates changes in the internal pressure of the exhaust passage 16. In FIG. 2 (a) or (b), the waveform indicated by the thin line indicates the pressure change when the waste gate valve (W / G) is closed, while the waveform indicated by the bold line indicates the pressure change when the valve is opened. Respectively.

  In one cycle of the internal combustion engine 10, exhaust generated by the explosion strokes of the # 1 to # 4 cylinders flows through the exhaust passages 16 and 18. That is, in the exhaust passage 16, exhaust pulsation having a cycle every 360 ° CA occurs due to the explosion strokes of the # 1 and # 4 cylinders. Similarly, in the exhaust passage 18, exhaust pulsation having a cycle every 360 ° CA occurs due to the explosion strokes of the # 2 and # 3 cylinders.

  When the waste gate valve 30 is closed, the exhaust passages 16 and 18 are independent. For this reason, exhaust pulsations having a period every 360 ° CA are generated in the exhaust passages 16 and 18, respectively. Therefore, as indicated by the thin line in FIG. 2A, the internal pressure of the exhaust passage 18 obtained by the pressure sensor 32 exhibits a peak characteristic for every 360 ° CA. Further, as indicated by the thin line in FIG. 2B, the internal pressure of the exhaust passage 16 exhibits a peak characteristic every 360 ° CA.

  On the other hand, when the waste gate valve 30 is open, the exhaust passage 16 communicates with the exhaust passage 18 via the bypass passages 24 and 26. For this reason, the exhaust generated by the explosion strokes of the # 1, # 4 cylinders affects the exhaust flowing through the exhaust passage 18 via the bypass passages 24, 26. Therefore, as indicated by the thick line in FIG. 2A, the internal pressure of the exhaust passage 18 obtained by the pressure sensor 32 exhibits a peak characteristic for each 180 ° CA. Similarly, the exhaust generated by the explosion strokes of the # 2 and # 3 cylinders affects the exhaust pulsation flowing through the exhaust passage 16 via the bypass passages 26 and 24. Therefore, as indicated by a thick line in FIG. 2B, the internal pressure of the exhaust passage 16 exhibits a peak characteristic for each 180 ° CA.

  Thus, the peak characteristics of the internal pressure of the exhaust passages 16 and 18 change depending on whether the waste gate valve 30 is opened or closed. Thereby, the operation state of the waste gate valve 30 can be determined. When the waste gate valve 30 is opened, the number of internal pressure waves (the number of peaks) is the same as the number of cylinders. Therefore, in the system of the first embodiment, the failure diagnosis of the waste gate valve 30 is performed using the waveform acquired by the pressure sensor 32 as the peak characteristic of the internal pressure.

  The failure of the waste gate valve 30 includes closed adhesion and open adhesion. For example, even if the waste gate valve 30 is controlled to be opened by the ECU 50, if the waveform acquired by the pressure sensor 32 is a waveform when the valve is closed, it can be determined that the valve is stuck closed. Further, for example, if the waveform acquired by the pressure sensor 32 is a waveform at the time of valve opening even though the waste gate valve 30 is controlled to close, it can be determined that the valve is stuck open.

  The operating waveform of the waste gate valve 30 can be determined by using the waveform acquired by the pressure sensor 32 as it is. However, when performing failure diagnosis, it is preferable to derive the number of peaks from the acquired waveform and use it. . When the number of peaks is used, the failure diagnosis can be performed, for example, by comparing the number of peaks with a theoretical number of peaks calculated based on switching information.

  The theoretical number of peaks is set to a different value when the waste gate valve 30 is opened and when the valve is closed. The theoretical peak number Nopen at the time of valve opening is a value corresponding to the total number of cylinders included in the cylinder group. On the other hand, the theoretical peak number Nclose when the valve is closed is a value corresponding to the number obtained by dividing the total number of cylinders included in the cylinder group by the number of turbine inlets. In the present embodiment, # 1 to # 4 cylinders constitute one cylinder group, and the number of turbine inlets is two. For this reason, for example, if one cycle is considered, Nopen can be 4 and Nclose can be 2. Nopen and Nclose can be changed in accordance with the waveform sampling time. These Nopen and Nclose values are stored in the ECU 50 in advance.

  As described above, according to the system of the first embodiment, the failure diagnosis of the waste gate valve 30 can be performed using the acquisition form from the pressure sensor 32. In other words, the failure diagnosis of the waste gate valve 30 can be performed only by using the pressure sensor 32. Therefore, according to the system of the first embodiment, failure diagnosis of the waste gate valve 30 can be easily performed. In addition, the lift sensor and the exhaust temperature sensor that are conventionally required for failure diagnosis become unnecessary, and the waste gate device can be reduced in weight and cost.

  Further, according to the system of the first embodiment, failure diagnosis of the waste gate valve 30 can be performed regardless of the operating state of the turbocharger 20. That is, regardless of whether there is a supercharge request for the turbocharger 20, it is possible to perform a failure diagnosis of the waste gate valve 30 in a wide range of operation.

[Specific Processing in Embodiment 1]
FIG. 3 is a flowchart of a failure diagnosis routine of the waste gate valve 30 executed by the ECU 50 in the present embodiment. This routine is repeatedly performed for each cycle of the internal combustion engine 10, for example.

  First, in step 100, opening / closing information of the waste gate valve 30 is acquired (step 100). As described above, the waste gate valve 30 is controlled to open and close. Specifically, the waste gate valve 30 is controlled to be opened and closed by the ECU 50 by a routine different from the routine shown in FIG. For this reason, the ECU 50 acquires the opening / closing information from this other routine.

  Subsequently, in step 110, the number of peaks is acquired from the acquired waveform. As described above, an output waveform corresponding to the pressure in the exhaust passage 18 is input to the ECU 50 by the pressure sensor 32. For this reason, the ECU 50 acquires the number of peaks based on this waveform.

  Subsequently, in step 120, it is determined whether or not the control command value of the waste gate valve 30 is steady. As described above, the waste gate valve 30 is controlled to open and close based on a routine different from the routine shown in FIG. Further, the command information for the opening / closing control is acquired by the ECU 50 in step 100. Therefore, in this step, it is determined whether or not the value of the opening / closing command is steady. As a result, if it is determined that it is steady, the process proceeds to step 130, and if it is determined that it is not steady, the process returns to step 100.

  In step 130, it is determined whether or not the control command value of the waste gate valve 30 is in the valve open state. If it is determined that the valve is open, the theoretical peak number Nopen corresponding to the valve open state is read into the ECU 50 in step 140. On the other hand, if it is determined that the valve is not open, the ECU 50 reads the theoretical peak number Nclose corresponding to the valve closed state in step 150.

  Subsequently, in step 160, the peak number acquired in step 110 is compared with the theoretical peak number read in step 140 or 150. As a result, if both coincide, the routine proceeds to step 170, where it is diagnosed that the waste gate valve is not in failure. On the other hand, if they do not match, the routine proceeds to step 180 where a failure of the waste gate valve is diagnosed.

  As described above, according to the failure diagnosis routine of FIG. 3, the number of peaks of the output waveform corresponding to the pressure in the exhaust passage 18 is compared with the theoretical number of peaks to accurately determine whether the waste gate valve 30 is in failure. Can be diagnosed.

  In the first embodiment, the in-line four-cylinder internal combustion engine 10 is used. However, the number of cylinders and the cylinder arrangement of the internal combustion engine 10 are not limited to this. As described above, the theoretical peak number Nopen when the waste gate valve 30 is opened is a value corresponding to the total number of cylinders constituting the cylinder group. Further, the theoretical peak number Nclose when the valve is closed is a value corresponding to the number obtained by dividing the total number of cylinders per cylinder group by the number of inlets of the turbocharger 20. For this reason, for example, if the number of inlets is 2 in an in-line 6-cylinder internal combustion engine, there are 6 cylinders and 2 inlets per cylinder group, so Nopen can be 6 and Nclose can be 3. Furthermore, for example, in a V-type 8-cylinder twin turbo internal combustion engine, if the number of inlets per turbocharger is 2, there are 4 cylinders and 2 inlets per cylinder group, so Nopen is 4 and Nclose is 2. Can do. This modification is the same in the second embodiment to be described later.

  In the first embodiment, the pressure sensor 32 is disposed only in the exhaust passage 18 and the failure diagnosis of the waste gate valve 30 is performed. However, a pressure sensor may be disposed in the exhaust passage 16. In this way, a highly accurate failure diagnosis can be realized based on the pressure information acquired from the two pressure sensors. This modification is the same in the second embodiment to be described later.

  In the first embodiment, only one waste gate valve 30 is disposed in the bypass passages 24 and 26, and the exhaust passages 16 and 18 and the exhaust passage 22 are simultaneously communicated or blocked by being controlled to open and close. However, the waste gate valve may be arranged for each of the bypass passages 24 and 26. In this case, the waste gate valves are simultaneously controlled to open and close by the ECU 50. For this reason, the combination of the two waste gate valves and the arrangement of the pressure sensor 32 enables failure diagnosis of one or both of the waste gate valves. This modification is the same in the second embodiment to be described later.

  In the first embodiment described above, the exhaust manifolds 12 and 14 and the exhaust passages 16 and 18 are the “plural upstream exhaust passages” in the first invention, and the exhaust passage 22 is the “downstream” in the first invention. Corresponds to the “side exhaust passage”. Further, when the ECU 50 executes the process of step 110, the “exhaust pressure acquisition means” in the first aspect of the invention executes the series of processes of steps 130 to 180. Each of the “operating state determination means” is realized.

    In the first embodiment described above, the ECU 50 executes the process of step 100, so that the “command information acquisition means” in the second invention executes the series of processes of steps 130 to 180. Thus, the “fault diagnosis means” in the second invention is realized.

  In the first embodiment described above, the “frequency comparison means” according to the third aspect of the present invention is implemented when the ECU 50 executes the processing of step 160.

  Further, in the first embodiment described above, the “peak number comparing means” in the fourth aspect of the present invention is realized by the ECU 50 executing the processing of step 160.

Embodiment 2. FIG.
[Description of System Configuration of Embodiment 2]
The system of the second embodiment is characterized in that a pressure sensor 34 is used instead of the pressure sensor 32 used in the system of the first embodiment. For this reason, it demonstrates centering around difference with Embodiment 1 mentioned above, and the description is abbreviate | omitted or simplified about the same matter.

  In the exhaust passages 16 and 18, bypass passages 24 and 26 for flowing the exhaust to the exhaust passage 22 while avoiding the turbocharger 20 are arranged, respectively. In addition, in the bypass passages 24 and 26, a waste gate valve 30 capable of opening / closing control is disposed.

  An exhaust passage 22 is connected to the downstream outlet of the turbocharger 20. A catalyst 28 for purifying the exhaust gas is disposed in the exhaust passage 22. A pressure sensor 34 is disposed between the catalyst 28 and the turbocharger 20. The pressure sensor 34 is configured to generate an output in accordance with the pressure inside the exhaust passage 22.

  FIG. 5 is a view for explaining exhaust pulsation downstream of the turbine. The horizontal axis in FIG. 5 indicates the crank angle (CA) as in FIG. Two waveforms shown in FIG. 5 indicate exhaust pulsations in the exhaust passage 22, that is, changes in the internal pressure of the exhaust passage 22 acquired by the pressure sensor 34. In FIG. 5, a waveform indicated by a thin line indicates a pressure change when the waste gate valve (W / G) is closed, while a waveform indicated by a thick line indicates a pressure change when the valve is opened.

  When the waste gate valve 30 is closed, the exhaust generated in the explosion strokes of the # 1 to # 4 cylinders flows into the exhaust passage 22 every 180 ° CA. The exhaust is attenuated when it flows through the exhaust passage 22 via the turbocharger 20. Therefore, as shown by the thin line in FIG. 5, the internal pressure of the exhaust passage 22 acquired by the pressure sensor 34 has a weak peak intensity that appears every 180 ° CA.

  On the other hand, when the waste gate valve 30 is open, the exhaust passages 16 and 18 are communicated with the exhaust passage 22 via the bypass passages 24 and 26. For this reason, exhaust pulsation that is not attenuated by the turbocharger 20 flows directly into the exhaust passage 22. Therefore, as shown by the thick line in FIG. 5, the peak intensity of the internal pressure of the exhaust passage 22 obtained by the pressure sensor 34 is stronger than when the waste gate valve 30 is closed.

  Thus, the peak intensity of the internal pressure of the exhaust passage 22 changes depending on whether the waste gate valve 30 is opened or closed. Thereby, the operation state of the waste gate valve 30 can be determined. In the system of the second embodiment, the peak intensity of the waveform acquired by the pressure sensor 34 is obtained, and failure diagnosis of the waste gate valve 30 is performed.

  The failure of the waste gate valve 30 includes closed adhesion and open adhesion. For example, when the waste gate valve 30 is controlled to be opened by the ECU 50, if the peak intensity of the waveform acquired by the pressure sensor 34 is the peak intensity when the valve is closed, it can be determined that the valve is closed. Further, for example, if the peak intensity of the waveform acquired by the pressure sensor 34 is the peak intensity at the time of valve opening even though the waste gate valve 30 is controlled to be closed, it can be determined that the valve is stuck open.

  The failure diagnosis can be performed, for example, by comparing the average value Iaverage of the peak intensity per sampling frequency with the theoretical peak intensity calculated based on the switching information. The theoretical peak intensity is set to a different value when the waste gate valve 30 is opened and when the valve is closed. The theoretical peak intensity Iopen at the time of valve opening and the theoretical peak intensity Iclose at the time of valve closing are obtained by experiments or the like corresponding to the load of the internal combustion engine 10. The average peak intensity value Iaverage is compared with the theoretical peak intensity by comparing the absolute value of the difference between the two and a preset threshold value. These Iopen, Iclose, and threshold values are stored in the ECU 50 in advance.

  As described above, according to the system of the second embodiment, the failure diagnosis of the waste gate valve 30 can be performed using the acquisition form from the pressure sensor 34. Therefore, according to the system of the second embodiment, the same effect as that of the first embodiment can be obtained.

[Specific Processing in Second Embodiment]
FIG. 6 is a flowchart of a failure diagnosis routine of the waste gate valve 30 executed by the ECU 50 in the present embodiment. For example, this routine is repeatedly performed every four cycles of the internal combustion engine 10.

  First, after the opening / closing command information of the waste gate valve 30 is acquired in step 100, in step 200, the average value Iaverage of the peak intensity of exhaust pulsation is acquired. As described above, an output waveform corresponding to the internal pressure of the exhaust passage 22 is input to the ECU 50 by the pressure sensor 34. Therefore, the ECU 50 acquires the average value Iaverage of the peak intensity of the exhaust pulsation based on this waveform.

  Subsequently, in step 120, it is determined whether or not the control command value of the waste gate valve 30 is steady. As a result, if it is determined that it is steady, the process proceeds to step 130, and if it is determined that it is not steady, the process returns to step 100.

  In step 130, it is determined whether or not the control command value of the waste gate valve 30 is in the valve open state. If it is determined that the valve is open, the theoretical peak intensity Iopen corresponding to the valve open state is read into the ECU 50 in step 210. On the other hand, if it is determined that the valve is not open, the theoretical peak intensity Iclose corresponding to the valve closed state is read into the ECU 50 in step 220.

  Subsequently, in step 230, the average value Iaverage of peak intensities acquired in step 200 is compared with the theoretical peak intensities read in step 210 or 220. As a result, when the absolute value of the difference between the two is smaller than the threshold value, the routine proceeds to step 240, where it is diagnosed that the waste gate valve is not in failure. On the other hand, if they do not match, the routine proceeds to step 250 where failure of the waste gate valve is diagnosed.

  As described above, according to the failure diagnosis routine of FIG. 6, the peak intensity of the output waveform corresponding to the internal pressure of the exhaust passage 22 is compared with the theoretical peak intensity to accurately determine whether the waste gate valve 30 is in failure. Can be diagnosed.

  In the second embodiment, the pressure sensor 34 is arranged in the exhaust passage 22 and the failure diagnosis of the waste gate valve 30 is performed from the peak intensity of the exhaust pulsation acquired from the pressure sensor 34. Similarly, the failure sensor of the waste gate valve 30 may be diagnosed by arranging the pressure sensor 32 in the exhaust passage 18 and combining the peak number of exhaust pulsation acquired from the pressure sensor 32. By doing so, more accurate fault diagnosis can be realized.

  In the second embodiment described above, the “amplitude comparing means” according to the fifth aspect of the present invention is realized by the ECU 50 executing the process of step 230.

2 is a diagram for describing a system configuration according to Embodiment 1. FIG. It is a figure for demonstrating the exhaust pulsation in a turbine upstream. 4 is a flowchart of a failure diagnosis routine for waste gate valve 30 executed by ECU 50 in the first embodiment. FIG. 4 is a diagram for explaining a system configuration of a second embodiment. It is a figure for demonstrating the exhaust pulsation in the turbine downstream. 7 is a flowchart of a failure diagnosis routine for waste gate valve 30 that is executed by ECU 50 in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12, 14 Exhaust manifold 16, 18 Exhaust passage 20 Turbocharger 22 Exhaust passage 24, 26 Bypass passage 30 Wastegate valve 32, 34 Pressure sensor 50 ECU

Claims (5)

A turbocharger having a turbine with a plurality of inlets;
A plurality of upstream exhaust passages arranged upstream of the turbocharger and communicating the plurality of inlets with a cylinder group of an internal combustion engine;
A downstream exhaust passage disposed downstream of the turbocharger;
A plurality of bypass passages that connect the plurality of upstream exhaust passages and the downstream exhaust passage without passing through the turbine;
A wastegate valve capable of opening and closing the plurality of bypass passages;
Exhaust pressure acquisition means for acquiring exhaust pressure in at least one of the plurality of upstream exhaust passages and / or in the downstream exhaust passage;
An operation state determination means for determining an operation state of the waste gate valve based on the exhaust pressure;
A control device for an internal combustion engine, comprising: Command information obtaining means for obtaining opening / closing command information of the waste gate valve;
A failure diagnosis means for diagnosing a failure of the waste gate valve based on the waveform information of the exhaust pressure and the opening / closing command information;
The control apparatus for an internal combustion engine according to claim 1, comprising: The waveform information is a frequency of exhaust pulsation in the at least one exhaust passage,
The control apparatus for an internal combustion engine according to claim 2, wherein the failure diagnosis means includes frequency comparison means for comparing the frequency of the exhaust pulsation with a theoretical frequency corresponding to the opening / closing command information. . The frequency comparison means comprises peak number comparison means for comparing the peak number of exhaust pulsation per cycle of the internal combustion engine with the theoretical peak number of exhaust pulsation,
The theoretical peak number of exhaust pulsation corresponds to the total number of cylinders included in the cylinder group when the waste gate valve is opened, and the total number of cylinders included in the cylinder group when the waste gate valve is closed. 4. The control apparatus for an internal combustion engine according to claim 3, wherein a number corresponds to a number divided by the number of the plurality of inlets.   The control apparatus for an internal combustion engine according to claim 2, wherein the waveform information is an amplitude of exhaust pulsation in the downstream exhaust passage.

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