JP2010209883A - Ignition device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform stable engine operation even when abnormality occurs in a plasma ignition means in an ignition device of an internal combustion engine. <P>SOLUTION: This ignition device of the internal combustion engine includes the plasma ignition means for igniting an air-fuel mixture in a cylinder by plasma ignition, an abnormality determining means for determining abnormality of the plasma ignition means, a combustion fluctuation suppressing means for performing control to suppress combustion fluctuation of the internal combustion engine when the plasma ignition means is determined to be abnormal, and a spark ignition means for igniting the air-fuel mixture in the cylinder by spark ignition in place of plasma ignition when the plasma ignition means is determined to be abnormal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  An ignition device that generates plasma and ignites an air-fuel mixture in a cylinder is known (see, for example, Patent Documents 1 and 2).

JP 2008-121462 A Japanese Patent Publication No.63-28234

  In an internal combustion engine provided with plasma ignition means, ignition can be promoted and combustion can be stabilized by performing plasma ignition even in an operating state in which ignition is not sufficiently performed by spark ignition. However, when the plasma ignition means breaks down, combustion becomes unstable and misfire tends to occur, which may cause problems such as torque fluctuation.

  The present invention has been made to solve the above-described problems, and provides an ignition device for an internal combustion engine capable of performing stable engine operation even when an abnormality occurs in plasma ignition means. With the goal.

In order to achieve the above object, a first invention is an ignition device for an internal combustion engine,
Plasma ignition means for igniting the air-fuel mixture in the cylinder by plasma ignition;
An abnormality determining means for determining an abnormality of the plasma ignition means;
Combustion fluctuation suppressing means for performing control for suppressing combustion fluctuation of the internal combustion engine when the plasma ignition means is determined to be abnormal;
Spark ignition means for igniting an air-fuel mixture in a cylinder by spark ignition instead of plasma ignition when it is determined that the plasma ignition means is abnormal;
It is characterized by providing.

The second invention is the first invention, wherein
Torque fluctuation detecting means for detecting torque fluctuation of the internal combustion engine;
The abnormality determining means suppresses the combustion fluctuation by limiting a predetermined parameter of the internal combustion engine when the torque fluctuation during ignition by plasma ignition is larger than a first predetermined value, and from the plasma ignition. Switching to spark ignition is performed to perform ignition, and when the torque fluctuation after switching to spark ignition becomes smaller than a second predetermined value, it is determined that the plasma ignition means is abnormal.

The third invention is the first or second invention, wherein
A turbocharger,
A bypass passage for bypassing the turbocharger turbine;
A waste gate valve for opening and closing the bypass passage;
With
The combustion fluctuation suppressing means suppresses combustion fluctuation by opening the waste gate valve and lowering the boost pressure from the normal time when it is determined that the plasma ignition means is abnormal. To do.

According to a fourth invention, in any one of the first to third inventions,
An exhaust gas recirculation device for recirculating a part of the exhaust gas of the internal combustion engine to the intake system;
The combustion fluctuation suppressing means suppresses the combustion fluctuation by reducing the exhaust gas recirculation amount from the normal time when it is determined that the plasma ignition means is abnormal.

  According to the first invention, when it is determined that the plasma ignition means is abnormal, the control for suppressing the combustion fluctuation of the internal combustion engine can be performed, and the spark ignition can be performed instead of the plasma ignition. For this reason, even if an abnormality occurs in the plasma ignition means, it is possible to reliably suppress the occurrence of misfires, torque fluctuations, and the like, and the engine operation can be continued stably.

  According to the second invention, it is possible to accurately determine abnormality of the plasma ignition means.

  According to the third invention, when it is determined that the plasma ignition means is abnormal, the combustion fluctuation is easily and reliably suppressed by opening the waste gate valve and lowering the supercharging pressure from the normal time. Can do.

  According to the fourth invention, when it is determined that the plasma ignition means is abnormal, the combustion fluctuation can be easily and reliably suppressed by reducing the exhaust gas recirculation amount from the normal time.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10. Each cylinder of the internal combustion engine 10 is provided with a fuel injector 12 that injects fuel directly into the cylinder. The present invention is not limited to such an in-cylinder injection type internal combustion engine, but can be similarly applied to a port injection type internal combustion engine that injects fuel into an intake port.

  The exhaust gas discharged from each cylinder of the internal combustion engine 10 is collected by the exhaust manifold 20 and flows into the exhaust passage 18. The internal combustion engine 10 includes a turbocharger (supercharger) 24 that performs supercharging with the energy of exhaust gas. The turbocharger 24 includes a turbine 241 and a compressor 242. The turbine 241 is disposed in the middle of the exhaust passage 18, and the compressor 242 is disposed in the middle of the intake passage 28.

  An exhaust purification catalyst 26 is installed in the exhaust passage 18 on the downstream side of the turbine 241. An air cleaner 30 is provided near the inlet of the intake passage 28. An air flow meter 38 for detecting the intake air amount is installed in the vicinity of the downstream side of the air cleaner 30.

  An intercooler 32 is installed in the intake passage 28 on the downstream side of the compressor 242. The fresh air that has passed through the intercooler 32 passes through the intake manifold 34 and flows into each cylinder. A throttle valve 36 is provided between the intercooler 32 and the intake manifold 34.

  A bypass passage 25 that bypasses the turbine 241 and a waste gate valve 27 that opens and closes the bypass passage 25 are provided in the vicinity of the turbine 241. The opening degree of the waste gate valve 27 is controlled by an ECU 50 (Electronic Control Unit).

  The internal combustion engine 10 includes an EGR passage 40 capable of performing EGR (Exhaust Gas Recirculation) for returning a part of the exhaust gas to the intake passage 28. In the middle of the EGR passage 40, an EGR catalyst 41, an EGR cooler 43, and an EGR valve 44 are provided.

  In addition to the various sensors and actuators described above, the ECU 50 includes a crank angle sensor 45 that detects the crank angle of the internal combustion engine 10, an accelerator opening sensor 46 that detects the accelerator pedal position of the vehicle, and a spark ignition device 47. The plasma ignition device 48 and a supercharging pressure sensor 49 for detecting the supercharging pressure are electrically connected.

  The spark ignition device 47 is a device that includes a spark plug installed in each cylinder and ignites an air-fuel mixture in the cylinder by generating a spark with the spark plug. The plasma ignition device 48 includes a plasma plug installed in each cylinder and ignites an air-fuel mixture in the cylinder by generating plasma by the plasma plug.

  FIG. 2 is a flowchart of a routine executed by the ECU 50 in the present embodiment. According to the routine shown in FIG. 2, first, a comparison between the supercharging pressure detected by the supercharging pressure sensor 49 and a predetermined specified pressure, and a comparison between the opening of the EGR valve 44 and a predetermined specified opening Are executed (step 100).

  In step 100, if the supercharging pressure exceeds the specified pressure, or if the opening degree of the EGR valve 44 exceeds the specified opening degree, or if both are established, then the plasma is It is determined whether or not the plug is broken (step 102). In the present embodiment, the ECU 50 has a function of determining a failure (abnormality) of the plasma plug. The determination method will be described later.

  If no plasma plug failure is found in step 102, that is, if it can be estimated that the plasma plug is normal, plasma ignition by the plasma ignition device 48 is executed (step 104). In the high load region where the boost pressure is high and the high EGR region where the EGR amount is large, in the case of spark ignition, it is not easy to satisfactorily burn the air-fuel mixture in the cylinder, and the combustion tends to become unstable. On the other hand, according to the present embodiment, plasma ignition can be performed in a high load region or a high EGR region by performing the control as described above. According to plasma ignition, ignition can be promoted and combustion can be stabilized even in a high load region or a high EGR region. For this reason, the internal combustion engine 10 can be operated stably and smoothly.

  On the other hand, when the supercharging pressure is equal to or lower than the specified pressure and the opening degree of the EGR valve 44 is equal to or lower than the specified opening degree in step 100, reliable ignition is possible even in the case of spark ignition. Obtained and stable combustion is possible. Therefore, in this case, spark ignition is executed by the spark ignition device 47 (step 106).

  If it is determined in step 102 that the plasma plug has failed, the waste gate valve 27 is opened (step 108), and spark ignition is performed by the spark ignition device 47 (step 106). According to such control, when a plasma plug failure (abnormality) occurs in the operation region where plasma ignition is to be performed, spark ignition can be executed instead of plasma ignition. For this reason, since the air-fuel mixture in the cylinder can be ignited, the operation of the internal combustion engine 10 can be continued. Further, since the waste gate valve 27 is opened in the above step 108, the amount of exhaust gas flowing into the turbine 241 is reduced and the supercharging pressure is lowered. As the pressure in the exhaust manifold 20 (exhaust pressure) decreases, the amount of exhaust gas flowing into the EGR passage 40, that is, the EGR amount also decreases. Thereby, the driving | operation in a high load area | region and a high EGR area | region is avoided. For this reason, even when spark ignition is executed instead of plasma ignition, ignition can be made good and misfiring can be avoided reliably. Therefore, it is possible to reliably prevent the occurrence of adverse effects such as misfires and fluctuations in engine torque even when the plasma plug fails.

  Next, the abnormality determination method for the plasma ignition plug in the present embodiment will be described. FIG. 3 is a flowchart of a routine executed by the ECU 50 in order to determine abnormality of the plasma spark plug. According to the routine shown in FIG. 3, it is first determined whether or not plasma ignition is being performed (step 200). If plasma ignition is not being performed, the processing of this routine is terminated here.

  If it is determined in step 200 that plasma ignition is being performed, the torque fluctuation of the internal combustion engine 10 is then compared with the first specified value (first predetermined value) (step 202). ). According to a known method, the torque fluctuation can be calculated based on the engine rotation fluctuation measured by the crank angle sensor 45. In step 202, torque fluctuation is detected by such a method, and the detected torque fluctuation is compared with the specified value.

  If the plasma plug fails and normal plasma ignition cannot be performed in the operation region where plasma ignition is to be performed, stable combustion cannot be performed, and misfire is likely to occur. As a result, the torque fluctuation becomes larger than when the plasma plug is normal. The first specified value is set in advance as a value with which it can be determined whether or not the torque fluctuation is in a normal range. That is, if the torque fluctuation is equal to or less than the first specified value in step 202, it can be determined that normal plasma ignition is being performed because the torque fluctuation is in the normal range. Therefore, in this case, it is determined that there is no abnormality in the plasma plug (step 204).

  On the other hand, if the torque fluctuation exceeds the first specified value in step 202, there is a possibility that an abnormality has occurred in the plasma plug. In this case, next, a process for reducing the engine load or the EGR rate is executed (step 206). In this step 206, it is desirable to reduce the engine load or the EGR rate so as to enter an operation region where spark ignition is to be performed. Following the process of step 206, spark ignition is performed (step 208). Then, following the process of step 208, the torque fluctuation of the internal combustion engine 10 is detected again, and the detected torque fluctuation is compared with the second specified value (second predetermined value) (step 210). The second specified value is set in advance as a value that can determine whether or not the torque fluctuation is in the normal range, and may be the same value as the first specified value or a different value.

  In step 210, when the torque fluctuation is smaller than the second specified value, that is, when it is confirmed that the torque fluctuation is in the normal range when the spark ignition operation is performed, occurrence is confirmed in step 202. It can be inferred that torque fluctuations exceeding the normal range are caused by poor plasma ignition. Therefore, in this case, it is determined that the plasma plug is out of order (step 212).

  On the other hand, if the torque fluctuation exceeds the second specified value in step 210, that is, if it is confirmed that the torque fluctuation exceeds the normal range even after the spark ignition operation, step 202 is performed. It can be presumed that the torque fluctuation exceeding the normal range in which the occurrence is confirmed is caused by causes other than the plasma ignition failure. Therefore, in this case, it is determined that there is no abnormality in the plasma plug (step 204).

  In the first embodiment described above, the engine load or the EGR rate corresponds to the “predetermined parameter” in the second invention. Further, when the ECU 50 executes the process of step 104, the “plasma ignition means” in the first invention performs the process of step 108, and the “combustion fluctuation suppressing means” in the first invention. However, by executing the processing of step 106, the “spark ignition means” in the first invention performs the processing of the routine shown in step 102 and FIG. 3 in the first and second inventions. Each “abnormality determination unit” is realized.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Fuel injector 18 Exhaust passage 20 Exhaust manifold 24 Turbocharger 241 Turbine 242 Compressor 27 Wastegate valve 28 Intake passage 34 Intake manifold 36 Throttle valve 38 Air flow meter 40 EGR passage 41 EGR catalyst 43 EGR cooler 44 EGR valve 50 ECU

Claims (4)

Plasma ignition means for igniting the air-fuel mixture in the cylinder by plasma ignition;
An abnormality determining means for determining an abnormality of the plasma ignition means;
Combustion fluctuation suppressing means for performing control for suppressing combustion fluctuation of the internal combustion engine when it is determined that the plasma ignition means is abnormal;
Spark ignition means for igniting an air-fuel mixture in a cylinder by spark ignition instead of plasma ignition when it is determined that the plasma ignition means is abnormal;
An ignition device for an internal combustion engine, comprising: Torque fluctuation detecting means for detecting torque fluctuation of the internal combustion engine;
The abnormality determining means suppresses the combustion fluctuation by limiting a predetermined parameter of the internal combustion engine when the torque fluctuation during ignition by plasma ignition is larger than a first predetermined value, and from the plasma ignition. The ignition is performed by switching to spark ignition, and when the torque fluctuation after switching to spark ignition becomes smaller than a second predetermined value, it is determined that the plasma ignition means is abnormal. An ignition device for an internal combustion engine according to claim 1. A turbocharger,
A bypass passage for bypassing the turbocharger turbine;
A waste gate valve for opening and closing the bypass passage;
With
The combustion fluctuation suppressing means suppresses combustion fluctuation by opening the waste gate valve and lowering the boost pressure from the normal time when it is determined that the plasma ignition means is abnormal. The internal combustion engine ignition device according to claim 1 or 2. An exhaust gas recirculation device for recirculating a part of the exhaust gas of the internal combustion engine to the intake system;
The combustion fluctuation suppressing means suppresses combustion fluctuation by reducing an exhaust gas recirculation amount from a normal time when it is determined that the plasma ignition means is abnormal. An ignition device for an internal combustion engine according to any one of the preceding claims.

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