JP4868173B2 - Abnormality diagnosis device for internal combustion engine - Google Patents

Description

The present invention relates to an abnormality diagnosis apparatus for an internal combustion engine in which two intake port injection type 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 view of such circumstances. Accordingly, an object of the present invention is to provide an internal combustion engine provided with two intake port injection type fuel injection valves for each cylinder. It is an object of the present invention to provide an abnormality diagnosis device for an internal combustion engine that can identify an abnormal fuel injection valve when an abnormality occurs in the fuel injection valve.

To achieve the above object, the invention according to claim 1, in Rukoto provided each fuel injection valve for each intake port with each for each cylinder of the internal combustion engine provided with two intake ports, each cylinder In the abnormality diagnosis device for an internal combustion engine in which two fuel injection valves are respectively arranged at positions where fuel is injected toward different intake ports, when performing abnormality diagnosis of the fuel injection valve by the abnormality diagnosis means, The two fuel injection valves are switched one by one to determine whether there is torque fluctuation or combustion state fluctuation, and an abnormal fuel injection valve is selected from the two fuel injection valves based on the determination result. identify, while prohibiting any of the injection operation of the abnormal fuel injection valve when detecting an abnormal fuel injection valve in the cylinder, for the other cylinders, the abnormality of said two intake ports The injection operation of the fuel injection valve position for injecting fuel toward the intake port on the same side as the fuel injection valve is prohibited all the cylinders, which was to inject with increasing correction of the fuel only by the remaining fuel injection valve It is.

As described above, when the two 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. Therefore, when the abnormal fuel injection valve is operated for injection, The torque and combustion state of the internal combustion engine fluctuate. From this relationship, if it is determined whether or not there is torque fluctuation or combustion state fluctuation when two fuel injection valves of each cylinder are switched one by one and the fuel injection state is determined, the torque fluctuation or combustion state fluctuation immediately before the occurrence occurs. It can be specified that the fuel injection valve at the injection timing is abnormal.

In this case, according to the present invention, the injection operation of the remaining fuel injection valves is prohibited so that the injection operation of the fuel injection valves identified as abnormal is prohibited and the fuel amount corresponding to the required injection amount is injected only by the remaining fuel injection valves. Because it is configured with fail-safe means for increasing the amount of fuel, even if one of the two fuel injection valves of each cylinder becomes abnormal, the fuel corresponding to the required injection amount can be obtained with only the remaining fuel injection valves. It becomes possible to control the air-fuel ratio to the target air-fuel ratio by injecting the amount, and the operation of the internal combustion engine can be continued while suppressing deterioration of drivability and emission.

Further, in the present invention, when an abnormal fuel injection valve is detected in any cylinder, the injection operation of the abnormal fuel injection valve is prohibited, and the other cylinders are also in the two intake ports. All cylinders are prohibited from injecting fuel at the position where fuel is injected toward the intake port on the same side as the abnormal fuel injection valve, and fuel is increased and corrected only with the remaining fuel injection valves. Therefore, when one of the two fuel injection valves of each cylinder becomes abnormal, the fuel can be injected from the fuel injection valve at the same position in all the cylinders. As a result, it is possible to prevent the fuel spray shape (mixture formation state) of the cylinder having the abnormal fuel injection valve from being different from that of other cylinders, and to make the fuel spray shapes of all the cylinders the same. Torque fluctuations and the like due to differences in fuel spray shape between engine cylinders 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 for detecting 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. Thus, for each cylinder, the two fuel injection valves 21 are arranged at positions where fuel is injected toward different intake ports 31. 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 “No” in step 110, that is, if one of the two fuel injection valves A and B of any cylinder is abnormal, the routine proceeds to step 112, where the two intake valves All the cylinders are prohibited from injecting the fuel at the position where the fuel is injected toward the intake port 31 on the same side of the port 31 as the abnormal fuel injection valve. The injection amount of a normal fuel injection valve (fuel injection valve permitted to inject) is changed to an abnormal fuel injection valve (fuel injection valve permitted to inject). The increase correction is made by an amount corresponding to the injection amount of the fuel injection valve). 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 finished, the fuel injection valve B at a position where fuel is injected toward the intake port 31 on the same side as the abnormal fuel injection valve B of the two intake ports 31. The injection operation of all the cylinders is prohibited and only one fuel injection valve A is allowed to be injected, and the normal fuel injection valve A injection amount is increased by an amount corresponding to the injection amount of the fuel injection valve B prohibiting injection. To do.

  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.

Further, in the present embodiment, when detecting the abnormal fuel injection valve 21 in one of the cylinders, towards the intake port 31 on the same side as the abnormal fuel injection valves 21 of the two intake ports 31 Fuel Since all the cylinders are prohibited from performing the injection operation of the fuel injection valve 21 at the position where fuel is injected, fuel is injected from the fuel injection valve at the same position in all cylinders. It is possible to prevent the fuel spray shape (mixture formation state) from differing from that of other cylinders, to make the fuel spray shapes of all the cylinders the same, and to prevent torque fluctuations due to differences in fuel spray shapes between the cylinders. There is also an advantage that can be suppressed.

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 (1)

Fuel into different intake ports each for each intake port fuel injection valve provided in Rukoto respectively, the two fuel injection valves, respectively for each cylinder provided with a respective two intake ports for each cylinder of the internal combustion engine In the abnormality diagnosis device for an internal combustion engine arranged at a position for injecting
Wherein when the abnormality diagnosis of the fuel injection valve, the two fuel injection valves of each cylinder is injected by switching one by one to determine the presence or absence of fluctuation of the torque fluctuation or the combustion state based on the determination result Abnormality diagnosis means for identifying an abnormal fuel injection valve from the two fuel injection valves;
The injection amount of the remaining fuel injection valve is set so that the fuel injection valve corresponding to the required injection amount is injected only by the remaining fuel injection valve by prohibiting the injection operation of the abnormal fuel injection valve detected by the abnormality diagnosis means. A fail-safe means for correcting the increase,
It said fail-safe means, when the abnormal fuel injection valve in one of the cylinders is detected by the abnormality diagnosis means and to prohibit the injection operation of the abnormal fuel injection valve, also other cylinders, the 2 Prohibit all cylinders from injecting fuel to the intake port on the same side as the abnormal fuel injection valve of the two intake ports, and increase the fuel only with the remaining fuel injection valves An abnormality diagnosing device for an internal combustion engine characterized by performing injection after correction.

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