JP2009185740A - Abnormality diagnosing device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow an internal combustion engine provided with two fuel injection valves for each cylinder to identify the fuel injection valve with an abnormality when one of the fuel injection valves has an abnormality. <P>SOLUTION: The internal combustion engine includes two fuel injection valves 21 (A and B) for each cylinder. When diagnosing the abnormality of the fuel injection valves 21, the existence of a torque variation (or variation in combustion state) is determined by selectively causing the injection of the two fuel injection valves 21 of each cylinder. Based on the determination result, the fuel injection valve 21 with the abnormality is identified from the two fuel injection valves 21 of each cylinder. The injection operation of the fuel injection valves 21 at the same position as positions of the fuel injection valves 21 identified as abnormal is inhibited for all the cylinders, and injection amounts of the remaining fuel injection valves 21 are increasingly corrected so that only the remaining fuel injection valves 21 inject fuel amounts corresponding to a required fuel injection amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis device for an internal combustion engine in which a plurality of fuel injection valves are provided for each cylinder of the internal combustion engine.

  As described in Patent Document 1 (Japanese Patent Laid-Open No. 63-94057), atomization of fuel spray in each cylinder of an internal combustion engine, port wet reduction (reduction of fuel adhesion to the inner wall surface of the intake port), etc. For this purpose, a fuel injection valve is arranged in each of two intake ports of each cylinder of the internal combustion engine, and fuel is injected by two fuel injection valves for each cylinder.

Further, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-85176), based on the output of an air-fuel ratio sensor disposed in an exhaust merging portion where exhaust gases of each cylinder of an internal combustion engine gather and flow. Some cylinders determine whether or not there is an abnormality in the air-fuel ratio of each cylinder (abnormality of the fuel injection valve).
Japanese Unexamined Patent Publication No. 63-94057 (see page 3, FIG. 1 etc.) JP 2007-85176 A (see page 2 etc.)

  By the way, when the abnormality diagnosis technique described in Patent Document 2 is combined with an internal combustion engine provided with two fuel injection valves for each cylinder described in Patent Document 1, one of the two fuel injection valves for each cylinder is combined. Is abnormal, it is possible to identify the cylinder whose air-fuel ratio has become abnormal due to the abnormality of the fuel injection valve, but which of the two fuel injection valves of the abnormal cylinder is abnormal. It is not possible to specify whether it exists. For this reason, in a service factory or the like, it is necessary to replace both of the two fuel injection valves of the abnormal cylinder, and there is a problem that the replacement work takes time and the cost of replacement parts increases.

  The present invention has been made in consideration of such circumstances. Accordingly, an object of the present invention is to provide an abnormality of any fuel injection valve in an internal combustion engine provided with a plurality of fuel injection valves for each cylinder. An object of the present invention is to provide an abnormality diagnosis device for an internal combustion engine that can identify an abnormal fuel injection valve when the occurrence of this occurs.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided an abnormality diagnosis device for an internal combustion engine in which a plurality of fuel injection valves are provided for each cylinder of the internal combustion engine. When making a diagnosis, the plurality of fuel injection valves of each cylinder are switched and injected one by one to determine the presence or absence of torque fluctuation or combustion state fluctuation, and based on the determination result, the plurality of fuel injection valves. An abnormal fuel injection valve is identified from the inside.

  In this way, when the fuel injection valves of each cylinder are switched and injected one by one, the fuel is not normally injected from the abnormal fuel injection valve, so when the abnormal fuel injection valve is operated for injection, The torque and combustion state of the internal combustion engine vary. From this relationship, if it is determined whether or not there are torque fluctuations and combustion state fluctuations when a plurality of fuel injection valves of each cylinder are switched one by one, the injection immediately before the torque fluctuations and combustion state fluctuations occur It can be determined that the fuel injection valve at the time is abnormal.

  In this case, as in claim 2, the remaining fuel injection is performed so that the fuel injection valve identified as abnormal is prohibited from being injected and the fuel amount corresponding to the required injection amount is injected only by the remaining fuel injection valve. It is preferable to employ a configuration provided with fail-safe means for correcting the injection amount of the valve to increase. In this way, even when any of the plurality of fuel injection valves of each cylinder becomes abnormal, the fuel quantity corresponding to the required injection quantity is injected only with the remaining fuel injection valves, and the air-fuel ratio is set to the target air-fuel ratio. Therefore, it is possible to continue the operation of the internal combustion engine while suppressing deterioration of drivability and emission.

  Further, as in claim 3, when an abnormal fuel injection valve is detected in any of the cylinders, all cylinders are prohibited from injecting the fuel injection valve at the same position as the abnormal fuel injection valve. It is also possible to inject the fuel by increasing the amount of fuel using only the remaining fuel injection valves. In this way, when any one of the plurality of fuel injection valves in each cylinder becomes abnormal, fuel can be injected from the fuel injection valve at the same position in all the cylinders. It is possible to prevent the fuel spray shape of the cylinder having the mixture (formation state of the air-fuel mixture) from being different from that of the other cylinders, to make the fuel spray shape of all the cylinders the same, and the fuel spray shape between the cylinders of the internal combustion engine Torque fluctuations due to the difference can be suppressed.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 that introduces air into each cylinder of the engine 11, and a fuel injection that injects fuel into or near the intake port 31 connected to the intake manifold 20 of each cylinder. A valve 21 is attached. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  As shown in FIG. 2, each cylinder of the engine 11 is provided with two intake ports 31 and two exhaust ports 32, and a fuel injection valve 21 is provided at or near the two intake ports 31 of each cylinder. Has been placed. Each intake port 31 is opened and closed by an intake valve 33, and each exhaust port 32 is opened and closed by an exhaust valve 34. The fuel stored in the fuel tank 35 is pumped up by the fuel pump 36, and the fuel discharged from the fuel pump 36 is supplied to the fuel injection valves 21 of the respective cylinders through the fuel supply pipe 37.

  On the other hand, as shown in FIG. 1, the exhaust pipe 23 (exhaust passage) of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying exhaust gas is provided downstream of the exhaust gas sensor 24.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 29 that detects knocking vibration are attached to the cylinder block of the engine 11. A crank angle sensor 28 that outputs a pulse signal every time the crankshaft 27 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 27. Based on the output signal of the crank angle sensor 28, the crank angle and engine The rotation speed is detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) so that the fuel injection amount of the fuel injection valve 21 can be determined according to the engine operating state. The ignition timing of the spark plug 22 is controlled. Usually, the two fuel injection valves 21 arranged in each cylinder are controlled so that the fuel injection amount is the same (the ratio of the fuel injection amount is 50:50).

  Further, the ECU 30 executes a fuel injection valve abnormality diagnosis routine of FIG. 3 to be described later, so that when performing abnormality diagnosis of the fuel injection valve 21, the two fuel injection valves 21 of each cylinder are switched and injected one by one. Then, the presence or absence of torque fluctuation (or fluctuation of combustion state) is determined, and an abnormal fuel injection valve 21 is specified from the two fuel injection valves 21 based on the determination result. Hereinafter, for convenience of explanation, one of the two fuel injection valves 21 arranged in each cylinder is referred to as “fuel injection valve A”, and the other is referred to as “fuel injection valve B”.

  The fuel injection valve abnormality diagnosis routine of FIG. 3 is executed at a predetermined cycle during engine operation, and serves as abnormality diagnosis means in the claims. When this routine is started, first, in step 101, it is determined whether or not an abnormality diagnosis execution condition is satisfied. Here, the abnormality diagnosis execution conditions are, for example, [1] idle operation (or steady operation), [2] after the engine 11 has been warmed up, and [3] fuel injection valves A and B. No abnormality is detected in the engine control system except for the above. If all of these conditions are satisfied, the abnormality diagnosis execution condition is satisfied. If any one of the conditions is not satisfied, the abnormality diagnosis execution condition is Not established.

  If it is determined in step 101 that the abnormality diagnosis execution condition is not satisfied, this routine is terminated without performing the subsequent processing. If it is determined that the abnormality diagnosis execution condition is satisfied, the process proceeds to step 102. Then, the injection of one fuel injection valve A of all cylinders is permitted, the injection of the other fuel injection valve B is prohibited, and the injection of one fuel injection valve A of all cylinders is executed in order.

  Thereafter, the process proceeds to step 103, where it is determined whether or not torque fluctuation (or combustion state fluctuation) has occurred. At this time, the torque fluctuation (or combustion state fluctuation) determination method includes, for example, the fluctuation amount of the engine speed, the in-cylinder pressure (combustion pressure) detected by the in-cylinder pressure sensor (not shown) of each cylinder, and the exhaust gas sensor 24. Based on at least one of the air-fuel ratios of the exhaust gas detected in step 1, the torque fluctuation (or the combustion state fluctuation) is determined, or the ion current generated by the combustion of the air-fuel mixture is ignited. And the variation in the combustion state may be determined based on the ion current.

  If it is determined in step 103 that torque fluctuation (or combustion state fluctuation) has not occurred, the routine proceeds to step 104 where it is determined that one fuel injection valve A of all cylinders is normal. On the other hand, if it is determined in step 103 that torque fluctuation (or combustion state fluctuation) has occurred, the routine proceeds to step 105, where one fuel of the cylinder in which torque fluctuation (or combustion state fluctuation) has occurred. It is specified that the injection valve A is abnormal.

  After this, the routine proceeds to step 106 where the injection of the other fuel injection valve B of all cylinders is permitted, the injection of one fuel injection valve B is prohibited, and the injection of the other fuel injection valve B of all cylinders is sequentially performed. Execute.

  Thereafter, the routine proceeds to step 107, where it is determined whether or not torque fluctuation (or combustion state fluctuation) has occurred by the same method as in step 103. As a result, torque fluctuation (or combustion state fluctuation) occurs. If it is determined that there is not, the routine proceeds to step 108, where it is determined that the other fuel injection valves B of all the cylinders are normal.

  On the other hand, if it is determined in step 107 that torque fluctuation (or combustion state fluctuation) has occurred, the process proceeds to step 109 and the other fuel in the cylinder in which torque fluctuation (or combustion state fluctuation) has occurred. It is specified that the injection valve B is abnormal.

  Thereafter, the routine proceeds to step 110, where it is determined whether or not the fuel injection valves A and B of all cylinders are normal. If both the fuel injection valves A and B of all cylinders are normal, the routine proceeds to step 111. The routine proceeds to allow the fuel injection valves A and B of all the cylinders to be injected, and the routine ends.

  On the other hand, if it is determined as “No” in step 110, that is, if one of the two fuel injection valves A and B of any cylinder is abnormal, the process proceeds to step 112 and abnormal fuel is generated. All cylinders are prohibited from performing the injection operation of the fuel injection valve at the same position as the injection valve position, and in the next step 113, only the normal fuel injection valve (the fuel injection valve that is permitted to inject) is used. The injection amount of a normal fuel injection valve (a fuel injection valve for which injection is permitted) is increased and corrected by an amount corresponding to the injection amount of an abnormal fuel injection valve (a fuel injection valve for which injection is prohibited) so as to inject the fuel amount. . The processes in these steps 112 and 113 serve as fail-safe means in the claims.

  An execution example of the fuel injection valve abnormality diagnosis routine of FIG. 3 described above will be described with reference to the time chart of FIG. The example of FIG. 4 shows the behavior when the fuel injection valve B of the # 4 cylinder becomes abnormal in a 4-cylinder engine. In the example of FIG. 4, the abnormality diagnosis execution condition is satisfied at time t1, and the fuel injection valve abnormality diagnosis is started. First, the injection of one fuel injection valve A of all cylinders is permitted, and the other fuel injection is performed. The injection of the valve B is prohibited, and the injection of one fuel injection valve A of all cylinders is executed in the order of, for example, # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder.

  At the time t2 when the injection of one fuel injection valve A of all cylinders is completed, the injection of one fuel injection valve A of all cylinders is prohibited, the injection of the other fuel injection valve B is permitted, and the other of all cylinders The fuel injection valve B is injected in the order of, for example, # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder.

  It is monitored whether or not torque fluctuations (or fluctuations in the combustion state) have occurred during the period during which this fuel injection valve abnormality diagnosis is being executed. For example, if torque fluctuation (or fluctuation in combustion state) is detected during the period in which the injection of the other fuel injection valve B is being performed, the cylinder in which the torque fluctuation (or fluctuation in combustion state) has occurred ( In the example of FIG. 4, it is determined that the other fuel injection valve B of # 4 cylinder) is abnormal.

  In this case, at the time t3 when the fuel injection valve abnormality diagnosis is completed, all cylinders are prohibited from performing the injection operation of the fuel injection valve B at the same position as the abnormal fuel injection valve B. The injection amount of the normal fuel injection valve A is increased and corrected by an amount corresponding to the injection amount of the fuel injection valve B that permits the injection and prohibits the injection.

  According to the present embodiment described above, when an abnormality diagnosis of the fuel injection valve 21 (A, B) is performed, the two fuel injection valves 21 of each cylinder are switched and injected one by one to change the torque (or combustion state). And the abnormal fuel injection valve 21 is identified from the two fuel injection valves 21 based on the determination result, so that one of the fuel injection valves 21 is abnormal. In this case, the abnormal fuel injection valve 21 can be identified.

  In addition, in this embodiment, when any one of the fuel injection valves 21 is abnormal, the injection operation of the fuel injection valve 21 identified as abnormal is prohibited, and only the remaining fuel injection valves 21 correspond to the required injection amount. Since the injection amount of the remaining fuel injection valve 21 is corrected so as to inject the remaining fuel amount, the remaining fuel injection is performed regardless of which of the two fuel injection valves 21 of each cylinder becomes abnormal. It is possible to control the air-fuel ratio to the target air-fuel ratio by injecting a fuel amount corresponding to the required injection amount with only the valve 21 and to continue the operation of the engine 11 while suppressing deterioration of drivability and emission. There is also.

  Furthermore, in this embodiment, when an abnormal fuel injection valve 21 is detected in any cylinder, the injection operation of the fuel injection valve 21 at the same position as the position of the abnormal fuel injection valve 21 is prohibited for all cylinders. Since all the cylinders inject fuel from the fuel injection valve at the same position, the fuel spray shape (mixture formation state) of the cylinder having the abnormal fuel injection valve 21 is different from the other cylinders. It is possible to prevent this, and the fuel spray shapes of all the cylinders can be made the same, and there is also an advantage that torque fluctuations due to differences in fuel spray shapes among the cylinders can be suppressed.

  The present invention is not limited to a system in which two fuel injection valves are disposed per cylinder, and can be applied to a system in which three or more fuel injection valves are disposed per cylinder.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a schematic block diagram of two fuel-injection valves arrange | positioned at one cylinder, and its periphery part. It is a flowchart explaining the flow of a process of a fuel injection valve abnormality diagnosis routine. It is a time chart which shows the example of control at the time of performing a fuel injection valve abnormality diagnosis.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 (A, B) ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 24 ... Exhaust gas sensor, 30 ... ECU (abnormality diagnosis) Means, fail-safe control means), 31 ... intake port, 32 ... exhaust port

Claims (3)

In the internal combustion engine abnormality diagnosis device provided with a plurality of fuel injection valves for each cylinder of the internal combustion engine,
When performing an abnormality diagnosis of the fuel injection valve, the plurality of fuel injection valves of each cylinder are switched and injected one by one to determine the presence or absence of torque fluctuation or combustion state fluctuation, and based on the determination result, An abnormality diagnosis apparatus for an internal combustion engine, comprising abnormality diagnosis means for identifying an abnormal fuel injection valve from a plurality of fuel injection valves.   The injection amount of the remaining fuel injection valve is set so that the injection operation of the fuel injection valve identified as abnormal by the abnormality diagnosis means is prohibited and the fuel amount corresponding to the required injection amount is injected only by the remaining fuel injection valve. 2. The abnormality diagnosis apparatus for an internal combustion engine according to claim 1, further comprising fail-safe means for correcting the increase.   The fail-safe means prohibits all cylinders from injecting the fuel at the same position as the abnormal fuel injection valve when the abnormal diagnosis means detects an abnormal fuel injection valve in any cylinder. The abnormality diagnosis apparatus for an internal combustion engine according to claim 1 or 2, wherein the fuel is increased and corrected only by the remaining fuel injection valves.

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