JP4780026B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger, and relates to prevention of a decrease in exhaust efficiency during operation of the internal combustion engine.

  An engine having a first exhaust valve that opens and closes an exhaust passage that communicates with a turbine and a second exhaust valve that opens and closes an exhaust passage that does not pass through the turbine (hereinafter referred to as an “independent exhaust engine”) is known (for example, (See Patent Document 1). In the independent exhaust engine of Patent Document 1, after the first exhaust valve is opened, the second exhaust valve is opened in the first half of the exhaust stroke. As a result, exhaust pumping loss can be reduced, and output can be improved by supercharging even in a high rotation range.

JP-A-10-89106 JP 2000-73790 A JP 2000-45737 A

  By the way, in the independent exhaust engine, the driving state of the exhaust valve may be switched. For example, the opened first exhaust valve may be closed and the closed second exhaust valve may be opened.

  However, there is a possibility that the timing for switching the driving state of the exhaust valve varies due to individual differences of control devices, changes with time, and the like. As a result, when the drive state of the exhaust valve is switched, the exhaust passage area may be reduced or blocked, and exhaust efficiency may be reduced during engine operation. Then, a situation where the intake amount of fresh air into the cylinder decreases or a situation where the amount of gas remaining in the cylinder increases may occur. As a result, a decrease in the combustion speed may occur, leading to misfire and a decrease in engine output.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can prevent a decrease in exhaust efficiency during operation of the internal combustion engine.

In order to achieve the above object, a first invention is an internal combustion engine having a supercharger,
A first exhaust valve that opens and closes a first exhaust passage leading to the turbine of the supercharger;
A second exhaust valve for opening and closing a second exhaust passage leading to the downstream of the turbine;
When stopping the first exhaust valve or the second exhaust valve during operation of the internal combustion engine, the other second exhaust valve or the first exhaust valve is driven before stopping the first exhaust valve or the second exhaust valve. And a driving means.

The second invention is the first invention, wherein
The driving means drives both the first and second exhaust valves in the middle of switching the driving state of the first and second exhaust valves.

The third invention is the first invention, wherein
The driving means includes
A first arm connected to the first exhaust valve;
A second arm connected to the second exhaust valve;
A pin hole provided to communicate with the inside of the first arm and the second arm;
A pin movable in the pin hole,
When the first exhaust valve is stopped, the pin moves into the second arm, and when the second exhaust valve is stopped, the pin moves into the first arm.

Moreover, 4th invention is set in 3rd invention,
The pin is located in the first arm and the second arm in the middle of switching the driving state of the first and second exhaust valves.

Further, a fifth invention is any one of the first to fourth inventions,
A rotation speed fluctuation obtaining means for obtaining fluctuations in the rotation speed of the internal combustion engine;
Pressure detecting means for detecting the pressure of the intake system of the internal combustion engine;
And a failure detecting means for detecting a failure of the drive means based on the fluctuation of the rotational speed or the pressure of the intake system when the internal combustion engine is at high speed or at low speed and high load. .

Further, a sixth invention is any one of the first to fourth inventions,
Detecting means for detecting stop or driving of the first exhaust valve;
Failure detection means for detecting a failure of the drive means when the detection means detects the drive of the first exhaust valve during a cold start of the internal combustion engine in which the first exhaust valve is stopped by the drive means And further comprising.

  In the first invention, when the first exhaust valve or the second exhaust valve is stopped, the other second exhaust valve or the first exhaust valve is driven before the first exhaust valve or the second exhaust valve is stopped. It is done. Accordingly, at least one of the first exhaust valve and the second exhaust valve is driven during the operation of the internal combustion engine. Therefore, according to the first invention, it is possible to prevent a reduction in exhaust efficiency during operation of the internal combustion engine.

  In the second invention, when the driving state of the first exhaust valve and the second exhaust valve is switched, both the first exhaust valve and the second exhaust valve are driven during the switching. Thereby, when stopping a 1st exhaust valve or a 2nd exhaust valve, a 2nd exhaust valve or a 1st exhaust valve can be driven reliably.

  In 3rd invention, when stopping a 1st exhaust valve, a 2nd exhaust valve is driven by a pin moving in a 2nd arm. Further, when stopping the second exhaust valve, the first exhaust valve is driven by moving the pin into the first arm. Therefore, when the first exhaust valve or the second exhaust valve is stopped, the second exhaust valve or the first exhaust valve can be reliably driven.

  In the fourth aspect of the invention, when the driving state of the first exhaust valve and the second exhaust valve is switched, a pin is located in the first and second arms during the switching, so that the first exhaust valve and the second exhaust valve Both are driven. Thereby, when stopping a 1st exhaust valve or a 2nd exhaust valve, a 2nd exhaust valve or a 1st exhaust valve can be driven reliably.

  According to the fifth aspect of the present invention, it is possible to detect a failure of the drive means based on the fluctuation of the engine speed or the pressure of the intake system at the time of low rotation and high load or high rotation.

  According to the sixth aspect of the present invention, when the first exhaust valve is driven by the detection means at the cold start when the first exhaust valve is stopped, a failure of the drive means is detected. Thereby, it is possible to detect the deterioration of the emission during the cold start.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram showing a system configuration according to Embodiment 1 of the present invention. The system of the first embodiment is an independent exhaust engine having a supercharger (darbocharger).
The system shown in FIG. 1 includes an engine 1 having a plurality of cylinders 2. The pistons of the cylinders 2 are connected to a common crankshaft 4 via a crank mechanism. In the vicinity of the crankshaft 4, a rotational speed sensor 5 for detecting the engine rotational speed NE is provided.

  The engine 1 has an injector 6 corresponding to each cylinder 2. The injector 6 is configured to inject high pressure fuel directly into the cylinder 2. Each injector 6 is connected to a common delivery pipe 7. The delivery pipe 7 communicates with the fuel tank 9 via the fuel pump 8.

  Further, the engine 1 has an intake port 10 corresponding to each cylinder 2. The intake port 10 is provided with an intake valve 12 (symbol “In” may be attached). Connected to the intake valve 12 is a variable valve mechanism 13 that can change the valve opening characteristics (opening / closing timing and lift amount) of the intake valve 12. As the variable valve mechanism 13, a known electromagnetically driven valve mechanism, a mechanical variable valve mechanism, or the like can be used.

  Each intake port 10 is connected to an intake passage 16. A surge tank 17 is provided in the middle of the intake passage 16. The surge tank 17 is provided with a supercharging pressure sensor 18. The supercharging pressure sensor 18 is configured to detect the pressure of intake air (hereinafter referred to as “supercharging air”) supercharged by a compressor 24a described later, that is, the supercharging pressure.

  A throttle valve 20 is provided in the intake passage 16 upstream of the surge tank 17. The throttle valve 20 is an electronically controlled valve that is driven by a throttle motor 21. The throttle valve 20 is driven based on the accelerator opening AA detected by the accelerator opening sensor 23. A throttle opening sensor 22 is provided in the vicinity of the throttle valve 20. The throttle opening sensor 22 is configured to detect the throttle opening TA.

  An intercooler 24 is provided upstream of the throttle valve 20. The intercooler 24 is configured to cool the supercharged air.

  A compressor 26 a of the supercharger 26 is provided upstream of the intercooler 24. The compressor 26a is connected to the turbine 26b via a connecting shaft (not shown). The turbine 26b is provided in a first exhaust passage 32 described later. The turbine 26b is rotationally driven by exhaust dynamic pressure (exhaust energy), whereby the compressor 26a is rotationally driven.

  An air flow meter 28 is provided upstream of the compressor 26a. The air flow meter 28 is configured to detect an intake air amount Ga. An air cleaner 29 is provided upstream of the air flow meter 28. The upstream of the air cleaner 29 is open to the atmosphere.

  Further, the engine 1 includes a first exhaust valve 30A (symbol “Ex1” may be attached) and a second exhaust valve 30B (symbol “Ex2” may be attached) corresponding to each cylinder 2. Have. The first exhaust valve 30A opens and closes the first exhaust passage 32 that communicates with the turbine 26b. The turbine 26 b is configured to be rotationally driven by the exhaust dynamic pressure that flows through the first exhaust passage 32. The second exhaust valve 30B opens and closes the second exhaust passage 34 that does not pass through the turbine 26b and communicates with the downstream side of the turbine 26b.

  These exhaust valves 30A and 30B are connected to a variable valve mechanism 31 capable of changing the valve opening characteristics (opening / closing timing and lift amount) of the exhaust valves 30A and 30B. As the variable valve mechanism 31, similarly to the variable valve mechanism 13, a known hydraulic or mechanical (see FIG. 8) variable valve mechanism can be used.

  An air-fuel ratio sensor 40 for detecting the exhaust air-fuel ratio is provided in the exhaust passage 36 downstream from the junction of the first exhaust passage 32 and the second exhaust passage 34. A catalyst 42 for purifying exhaust gas is provided downstream of the air-fuel ratio sensor 40.

The system according to the first embodiment includes an ECU (Electronic Control Unit) 60 that is a control device.
The rotational speed sensor 5, the boost pressure sensor 17, the throttle opening sensor 22, the accelerator opening sensor 23, the air flow meter 28, the air-fuel ratio sensor 40, and the like are connected to the input side of the ECU 60. Further, an injector 6, a fuel pump 8, variable valve mechanisms 14 and 31, a throttle motor 21, and the like are connected to the output side of the ECU 60.
The ECU 60 calculates the fluctuation amount of the engine speed NE. Further, the ECU 60 calculates the engine load factor KL [%] based on the accelerator opening AA (or the throttle opening TA).

[Features of Embodiment 1]
In the independent exhaust engine, the driving state of the exhaust valves Ex1, Ex2 is determined according to the operating state (NE, KL, etc.) of the engine 1. During the engine operation, the drive state of the exhaust valves Ex1 and Ex2 may be switched according to a request from the driver or the vehicle. For example, from the driving state in which the first exhaust valve Ex1 is opened and the second exhaust valve Ex2 is closed, the opened driving state in which the first exhaust valve Ex1 is closed and the second exhaust valve Ex2 is opened. There is a case to switch to.

  However, there is a possibility that the timing for switching the driving state of the exhaust valve varies due to individual differences of control devices, changes with time, and the like. As a result, when the drive state of the exhaust valve is switched, the exhaust passage area may be reduced or blocked, and exhaust efficiency may be reduced during engine operation. If so, there is a possibility of causing a misfire and a decrease in engine output.

  Therefore, in the first embodiment, the driving state of the exhaust valve is switched in the order shown in FIG. FIG. 2 is a diagram for explaining the switching operation of the exhaust valve drive state in the first embodiment. Specifically, FIG. 2A shows a driving state before switching, FIG. 2B shows a driving state during switching, and FIG. 2C shows a driving state after switching. In FIG. 2, hatched exhaust valves Ex1 and Ex2 are opened exhaust valves.

  In Embodiment 1, the driving state shown in FIG. 2A is not directly switched to the driving state shown in FIG. 2C, but the driving state shown in FIG. That is, all the exhaust valves Ex1 and Ex2 are opened during the switching of the driving state, as shown in FIG. When the first exhaust valve Ex1 is stopped as shown in FIG. 2 (A) → FIG. 2 (C), the remaining second exhaust is stopped before the first exhaust valve Ex1 is stopped as shown in FIG. 2 (B). Valve Ex2 is driven.

[Specific Processing in Embodiment 1]
FIG. 3 is a flowchart showing a drive state switching control routine executed by ECU 60 in the first embodiment. This routine is started when the driving state of the exhaust valves Ex1 and Ex2 is switched according to a request from the driver or the vehicle.

  According to the routine shown in FIG. 3, first, the drive request and stop request of each exhaust valve Ex1, Ex2 are read (step 100). Here, when switching the drive state of the exhaust valves Ex1, Ex2, a drive request and a stop request are issued. For example, in order to switch from the driving state shown in FIG. 2 (A) to the driving state shown in FIG. 2 (B), the second exhaust valve Ex2 needs to be driven (opened), so that a driving request is issued. Furthermore, in order to switch from the driving state shown in FIG. 2B to the driving state shown in FIG. 2C, the first exhaust valve Ex1 needs to be stopped (closed), so a stop request is issued.

  Next, it is determined whether or not the drive request read in step 100 is the same as the current operating state of the exhaust valves Ex1 and Ex2 (step 102). This drive request is a request to drive (open) all the exhaust valves Ex1, Ex2. Therefore, in this step 102, it is determined whether or not all the exhaust valves Ex1, Ex2 are driven. The current operating status of the exhaust valves Ex1 and Ex2 should be determined based on the detection result by the sensor and the elapsed time since the drive request was issued (that is, the time lag required to open the exhaust valve). Can do.

  If it is determined in step 102 that the drive request is different from the current operating state of the exhaust valves Ex1, Ex2, it is determined that all the exhaust valves Ex1, Ex2 are not driven. In this case, the exhaust valve that has not been driven is driven (step 104). Thereafter, this routine is temporarily terminated.

  On the other hand, when it is determined in step 102 that the drive request is the same as the current operating state of the exhaust valves Ex1, Ex2, it is determined that all the exhaust valves Ex1, Ex2 are driven. In this case, it is determined whether or not the stop request read in step 100 is the same as the current operating state of the exhaust valves Ex1 and Ex2 (step 106). This stop request is a request to stop (close) one of the exhaust valves so that the drive state after switching is achieved.

  If it is determined in step 106 that the stop request is different from the current operating state of the exhaust valves Ex1 and Ex2, it is determined that any exhaust valve is not stopped after all the exhaust valves are driven. The In this case, the exhaust valve that has not been stopped is stopped (step 108). Thereafter, this routine is temporarily terminated.

  On the other hand, when it is determined in step 106 that the stop request is the same as the current operating state of the exhaust valves Ex1 and Ex2, it is determined that the switching of the driving state of the exhaust valves Ex1 and Ex2 is completed. In this case, this routine is temporarily terminated.

  As described above, according to the first embodiment, when switching the driving state of the exhaust valves Ex1, Ex2, any exhaust valve is stopped after all the exhaust valves Ex1, Ex2 are opened. Is done. That is, when the first exhaust valve Ex1 or the second exhaust valve Ex2 is stopped, the other second exhaust valve Ex1 or the second exhaust valve Ex2 is driven before the stop. Thus, at least one of the exhaust valves Ex1 and Ex2 is driven during engine operation. Therefore, when the driving state of the exhaust valves Ex1 and Ex2 is switched, the exhaust passage area is not reduced or blocked, and a reduction in exhaust efficiency during engine operation can be prevented.

In the first embodiment, the case where the present invention is applied to the engine 1 having two exhaust valves Ex1 and Ex2 for each cylinder has been described. However, three exhaust valves for each cylinder as shown in FIG. The present invention can also be applied to engines having Ex1, Ex2, and Ex3. FIG. 4 is a diagram for explaining the switching operation of the exhaust valve drive state in the modification of the first embodiment. The first exhaust valve Ex1 and the third exhaust valve Ex3 shown in FIG. 4 open and close the first exhaust passage 32, for example.
In this modification, when the drive state shown in FIG. 4A is switched to the drive state shown in FIG. 4C, all the exhaust valves Ex1, Ex2, Ex3 are opened as shown in FIG. 4B. The Therefore, as in the first embodiment, it is possible to prevent the exhaust efficiency from being lowered when the drive state is switched during engine operation.

  In the first embodiment and the modification, the supercharger 26 is the “supercharger” in the first invention, the engine 1 is the “internal combustion engine” in the first invention, and the turbine 26b is the first. In the “turbine” of the invention, the first exhaust passage 32 is the “first exhaust passage” in the first invention, and the first exhaust valve (Ex1) 30A and the third exhaust valve (Ex3) are the “first exhaust passage” in the first invention. Corresponds to “1 exhaust valve”. Further, in the first embodiment and the modification, the second exhaust passage 34 is the “second exhaust passage” in the first invention, and the second exhaust valve (Ex2) 30B is the “second exhaust” in the first invention. The rotation speed sensor 5 and the ECU 60 correspond to the “valve”, and the boost pressure sensor 17 corresponds to the “pressure detection means” in the fifth invention. Further, in the first embodiment, the “driving means” in the first and second inventions is realized by the ECU 60 executing the processing of steps 102 and 104, respectively.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
In the first embodiment, when the driving state of the exhaust valves Ex1 and Ex2 is switched, control is performed so that all the exhaust valves Ex1 and Ex2 pass through the opened state. In the second embodiment, the same operation as the control is realized by the hardware shown in FIGS.

  FIG. 5 is a side view showing the switching mechanism 50 for switching the driving state of the exhaust valves Ex1, Ex2 in the second embodiment. FIG. 6 is a top view of the switching mechanism 50 shown in FIG. The switching mechanism 50 according to the second embodiment is mounted on, for example, an independent exhaust engine system as shown in FIG.

  As shown in FIGS. 5 and 6, the switching mechanism 50 includes a first arm 51A for pushing down the first exhaust valve Ex1, and a second arm 51B for pushing down the second exhaust valve Ex2. The first arm 51A and the second arm 52B are provided so as to sandwich the holder 52 from both sides. A pressing force of a cam 58 provided on the cam shaft 57 is applied to the holder 52.

  Inside the first arm 51 </ b> A, the second arm 51 </ b> B, and the holder 52, pin holes 53 communicating with each other are provided. The pin hole 53 is provided with a pin 54 that can move in the pin hole 53. According to this configuration, the pressing force of the cam 58 is applied to the first arm 51, the second arm 51B, or both according to the position of the pin 54. The axial length of the pin 54 is longer than the width of the holder 52. The pin 54 is moved by a driving force of a driving mechanism (for example, a hydraulic mechanism) 55. A hydraulic lash adjuster 56 is connected to the end of the first and second arms 51A, 51B on the side not connected to the exhaust valves 30A, 30B. The hydraulic lash adjuster 56 urges the arms 51 </ b> A and 51 </ b> B to push up so that there is no clearance between the holder 52 and the peripheral surface of the cam 58.

[Features of Embodiment 2]
The operation of the switching mechanism 50 will be described with reference to FIG. FIG. 7 is a diagram for explaining the operation of the switching mechanism 50 in the second embodiment. Specifically, FIG. 7A shows the position of the pin 54 before switching, FIG. 7B shows the position of the pin 54 in the middle of switching, FIG. 7C shows the position of the pin 54 after switching, FIG.

  In the example shown in FIG. 7, the first exhaust valve Ex1 is opened and the second exhaust valve Ex2 is closed, and then the first exhaust valve Ex1 is closed and the second exhaust valve Ex2 is opened. The position control of the pin 54 at the time of switching to a state is shown.

  As described above, the axial length of the pin 54 is longer than the width of the holder 52. Therefore, from the state where the pin 54 is not engaged with the second arm 51B as shown in FIG. 7A, the state where the pin 54 is not engaged with the first arm 51A as shown in FIG. 7C. In the middle of switching, the state shown in FIG. That is, as shown in FIG. 7 (B), the pin 54 goes through a state of fitting into both the first arm 51A and the second arm 51B.

Therefore, in the second embodiment, when switching the driving state of the exhaust valves Ex1 and Ex2, any exhaust valve is stopped after all the exhaust valves Ex1 and Ex2 are opened. Therefore, when the driving state of the exhaust valves Ex1 and Ex2 is switched, the exhaust passage area is not reduced or blocked, and a situation in which the exhaust efficiency is reduced can be prevented.
Furthermore, according to the second embodiment, since the switching operation of the driving state is realized by hardware, the reliability of the operation of the exhaust valves Ex1 and Ex2 can be improved.

  By the way, the present invention can be applied to an engine having three exhaust valves Ex1, Ex2, and Ex3 for each cylinder as in the modification of the first embodiment. Specifically, a link mechanism may be provided on the first arm 51A so that the first exhaust valve Ex1 and the third exhaust valve Ex3 can be driven by the pressing force of the first arm 51A. Also in this case, since all the exhaust valves Ex1, Ex2, Ex3 are opened when the driving state is switched, the same effect as in the second embodiment can be obtained.

In the second embodiment, the configuration in which the pressing force of the cam 58 is directly transmitted to the holder 52 is described. However, the pressing force of the cam 58 is transmitted via the variable valve mechanism 70 as shown in FIG. The structure transmitted to the holder 52 can be used.
FIG. 8 is a side view showing a switching mechanism 50 and a variable valve mechanism 70 according to a modification of the second embodiment. As shown in FIG. 8, a variable valve mechanism 70 is disposed between the cam 58 and the switching mechanism 50. In the variable valve mechanism 70, the link mechanism including the control arm 72, the intermediate arm 73, and the like changes as the control shaft 71 rotates. Then, when the position of the roller 75 in the swing arm 74 changes, the valve opening characteristics of the exhaust valves Ex1 and Ex2 change.
The pressing force of the cam 58 is transmitted to the swing arm 74 via a roller 75 at the tip of the intermediate arm 73. The pressing force transmitted to the swing arm 74 is transmitted to the holder 52. The pressing force transmitted to the holder 52 is transmitted to at least one of the arms 51A and 51B via the pin 54.

  In the second embodiment, the first arm 51A is the “first arm” in the third and fourth inventions, and the second arm 51B is the “second arm” in the third and fourth inventions. The pin hole 53 corresponds to the “pin hole” in the third invention, and the pin 54 corresponds to the “pin” in the third and fourth inventions.

Embodiment 3 FIG.
A third embodiment of the present invention will be described with reference to FIG. 9 and FIG.
FIG. 9 is a side view showing a switching mechanism 50B according to the third embodiment.
The switching mechanism 50B shown in FIG. 9 includes a position sensor 59 in addition to the configuration shown in FIG. The position sensor 59 is disposed above the other end of the first arm 51A and detects the position of the first arm 51A. The position sensor 59 is connected to the input side of the ECU 60. Therefore, the ECU 60 detects the driving state of the first exhaust valve Ex1 based on the detection result of the position sensor 59. That is, in the third embodiment, the position sensor 59 is provided in order to detect the driving state (stopped or driven) of the first exhaust valve Ex1 that should be stopped at the cold start.

[Features of Embodiment 3]
In the first and second embodiments, switching of the driving states of the exhaust valves Ex1 and Ex2 is described.
By the way, for example, the drive state of the exhaust valves Ex1 and Ex2 may become abnormal due to pin sticking (sticking), a failure of the variable valve mechanism, or the like.

Therefore, in the third embodiment, a method for detecting an abnormality in the driving state of the exhaust valves Ex1, Ex2 will be described with reference to FIG.
FIG. 10 is a diagram for explaining a method of detecting an abnormal drive state of the exhaust valves Ex1 and Ex2 in the third embodiment. FIG. 10 shows a normal drive state, an abnormal drive state, and an abnormality detection method by the ECU 60 for each of high rotation, cold start, and low rotation high load. In FIG. 10, the underlined portions in the abnormally driven state column are the exhaust valves Ex1 and Ex2 that are abnormally driven.

(At high rotation)
At high speed, both exhaust valves Ex1 and Ex2 are opened if normal.
However, first, an abnormal driving state in which both the exhaust valves Ex1 and Ex2 are closed may occur. In this case, the burned gas is not exhausted and misfire occurs, so the engine speed NE is greatly reduced. Therefore, the abnormal drive state is detected by the fluctuation of the engine speed NE detected by the speed sensor 5.
As shown in FIG. 6, when the length of the pin 54 is longer than the width of the holder 52, the exhaust valves Ex1 and Ex2 are not closed even if the pin 54 is fixed. (The same applies to the cold start and low rotation and high load below).

  Second, although the first exhaust valve Ex1 is opened, an abnormal drive state in which the second exhaust valve Ex2 is closed may occur. In this case, since all the exhaust gas is supplied to the turbine 26b, the turbine rotation speed becomes high, and the supercharging pressure becomes higher than the reference value. Therefore, this abnormal drive state is detected by the boost pressure detected by the boost pressure sensor 17.

  Third, although the second exhaust valve Ex2 is opened, there may be an abnormal drive state in which the first exhaust valve Ex1 is closed. In this case, since no exhaust gas is supplied to the turbine 26b, the turbine rotational speed becomes low, and the supercharging pressure becomes lower than the reference value. Therefore, this abnormal drive state is detected by the boost pressure detected by the boost pressure sensor 17.

(At cold start)
At the time of cold start, in order to promote warming up of the catalyst 42, if normal, the first exhaust valve Ex1 is closed and the second exhaust valve Ex2 is opened.
However, first, an abnormal driving state in which both the exhaust valves Ex1 and Ex2 are closed may occur. In this case, as in the case of the high rotation, the abnormal drive state is detected based on the fluctuation of the engine speed NE.

  Second, an abnormal drive state in which both the exhaust valves Ex1 and Ex2 are opened may occur. In this case, since the first exhaust valve Ex1 is opened, the exhaust gas flows to the turbine 26b side. If it does so, the warming-up performance of the catalyst 42 will fall, and there exists a possibility of causing emission deterioration. In this case, it is difficult to detect the abnormal drive state based on the engine speed NE fluctuation and the supercharging pressure. Therefore, the abnormal drive state is detected based on the detection result of the position sensor 59.

Third, there may be an abnormal drive state in which the first exhaust valve Ex1 is opened and the second exhaust valve Ex2 is closed. Also in this case, the exhaust gas flows to the turbine 26b side, which may cause a decrease in the warm-up performance of the catalyst 42. Also in this case, the abnormal drive state is detected based on the detection result of the position sensor 59.
In order to detect the driving state of the second exhaust valve Ex2, it is conceivable to provide a position sensor on the second arm 51B side. However, it is sufficient to detect the drive state of the first exhaust valve Ex1 in order to grasp the possibility of the emission deterioration at the cold start. It is sufficient to detect the driving state of the second exhaust valve Ex2 at times other than during cold start (during high rotation or low rotation and high load). In addition, adding a position sensor causes an increase in cost. Therefore, in the third embodiment, no position sensor is provided on the second arm 51B side.

(At low rotation and high load)
At low rotation and high load, if normal, the first exhaust valve Ex1 is opened and the second exhaust valve Ex2 is closed.
However, first, an abnormal driving state in which both the exhaust valves Ex1 and Ex2 are closed may occur. In this case, the abnormal drive state is detected based on the fluctuation of the engine speed NE as in the case of the high rotation and the cold start.

  Second, an abnormal drive state in which both the exhaust valves Ex1 and Ex2 are opened may occur. In this case, since all the exhaust gas cannot be supplied to the turbine 26b, the turbine rotational speed becomes low and the supercharging pressure becomes lower than the reference value. Therefore, this abnormal drive state is detected by the boost pressure detected by the boost pressure sensor 17.

  Third, there may be an abnormal drive state in which the first exhaust valve Ex1 is closed and the second exhaust valve Ex2 is opened. Also in this case, since all exhaust gas cannot be supplied to the turbine 26b, the turbine rotational speed becomes low and the supercharging pressure becomes lower than the reference value. Therefore, this abnormal drive state is detected by the boost pressure detected by the boost pressure sensor 17.

  Therefore, in the third embodiment, the abnormal drive state of the exhaust valves Ex1 and Ex2 can be detected based on the fluctuation of the engine speed or the supercharging pressure at the time of high rotation or low rotation and high load. Further, during the cold start, the abnormal drive state of the exhaust valves Ex1, Ex2 can be detected based on the detection result of the position sensor 59. By detecting such an abnormal drive state, a failure of the switching mechanism 50B can be detected.

  In the third embodiment, the ECU 60 corresponds to the “failure detection means” in the fifth and sixth inventions, and the position sensor 59 corresponds to the “detection means” in the sixth invention.

It is a figure which shows the system configuration | structure by Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a figure for demonstrating switching operation | movement of the drive state of an exhaust valve. 4 is a flowchart showing a drive state switching control routine executed by ECU 60 in the first embodiment of the present invention. FIG. 10 is a diagram for explaining an operation of switching the drive state of the exhaust valve in the modification of the first embodiment of the present invention. In Embodiment 2 of this invention, it is a side view which shows the switching mechanism 50 which switches the drive state of exhaust valve Ex1, Ex2. FIG. 6 is a top view of the switching mechanism 50 shown in FIG. 5. In Embodiment 2 of this invention, it is a figure for demonstrating operation | movement of the switching mechanism 50. FIG. It is a side view which shows the switching mechanism 50 and the variable valve mechanism 70 by the modification of Embodiment 2 of this invention. It is a side view which shows the switching mechanism 50B by Embodiment 3 of this invention. In Embodiment 3 of this invention, it is a figure for demonstrating the method to detect the abnormal drive state of exhaust valve Ex1, Ex2.

Explanation of symbols

1 Engine 5 Speed Sensor 17 Supercharging Pressure Sensor 26 Supercharger 26b Turbine 30A First Exhaust Valve Ex1
30B Second exhaust valve Ex2
32 First exhaust passage 34 Second exhaust passage 50 Switching mechanism 51 First arm 52 Second arm 53 Pin hole 54 Pin 60 ECU

Claims (6)

An internal combustion engine having a supercharger,
A first exhaust valve that opens and closes a first exhaust passage leading to the turbine of the supercharger;
A second exhaust valve for opening and closing a second exhaust passage leading to the downstream of the turbine;
When stopping the first exhaust valve or the second exhaust valve during operation of the internal combustion engine, the other second exhaust valve or the first exhaust valve is driven before stopping the first exhaust valve or the second exhaust valve. An internal combustion engine comprising: The internal combustion engine according to claim 1,
The internal combustion engine, wherein the driving means drives both the first and second exhaust valves in the middle of switching the driving state of the first and second exhaust valves. The internal combustion engine according to claim 1,
The driving means includes
A first arm connected to the first exhaust valve;
A second arm connected to the second exhaust valve;
A pin hole provided to communicate with the inside of the first arm and the second arm;
A pin movable in the pin hole,
When the first exhaust valve is stopped, the pin moves into the second arm, and when the second exhaust valve is stopped, the pin moves into the first arm. . The internal combustion engine according to claim 3,
The internal combustion engine, wherein the pin is positioned in the first arm and the second arm in the middle of switching the driving state of the first and second exhaust valves. The internal combustion engine according to any one of claims 1 to 4,
A rotation speed fluctuation obtaining means for obtaining fluctuations in the rotation speed of the internal combustion engine;
Pressure detecting means for detecting the pressure of the intake system of the internal combustion engine;
And a failure detecting means for detecting a failure of the drive means based on the fluctuation of the rotational speed or the pressure of the intake system when the internal combustion engine is at high speed or at low speed and high load. Internal combustion engine. The internal combustion engine according to any one of claims 1 to 4,
Detecting means for detecting stop or driving of the first exhaust valve;
Failure detection means for detecting a failure of the drive means when the detection means detects the drive of the first exhaust valve during a cold start of the internal combustion engine in which the first exhaust valve is stopped by the drive means And an internal combustion engine.

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