JP2013113127A - Determination device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure both an opportunity for normal return determination in a separate injection mode and the accuracy of the normal return determination.SOLUTION: Opportunities for normal determination in a DUAL mode are increased by eliminating a separate injection rate from conditions for normal return determination (similar operation conditions) in the DUAL mode, and the effect of the separate injection rate is eliminated by executing normal determination respectively in a cylinder injection mode and in a port injection mode, in addition to the normal determination in the DUAL mode, to individually determine that an injector for cylinder injection and an injector for port injection are normal. Accordingly, the normal return determination in the DUAL mode can be accurately performed only with the similar operation conditions.

Description

  The present invention relates to a determination apparatus for an internal combustion engine that includes an in-cylinder injector that injects fuel into a cylinder and an intake-path injector that injects fuel into an intake passage (intake port).

  As an internal combustion engine (engine) mounted on a vehicle or the like, an in-cylinder injector that directly injects fuel into a cylinder (combustion chamber), and an intake passage injector that injects fuel into an intake passage (intake port) A so-called dual injection internal combustion engine is known. In such a dual-injection type internal combustion engine, in-cylinder injection mode (DI mode) in which fuel is injected only from the in-cylinder injector, and port injection mode in which fuel is injected only from the intake manifold injector (PFI mode), it is possible to selectively switch to any one of the fuel injection modes (DUAL mode) in which fuel is injected from both the in-cylinder injector and the intake passage injector. is there.

  Further, in an internal combustion engine mounted on a vehicle or the like, fuel system abnormality detection or misfire abnormality detection is performed. In such an abnormality detection process, the operation conditions (engine speed, engine load (load factor), and warm-up state (water temperature / cold temperature / water temperature / high temperature) at the time of abnormality detection are stored, and the same or similar to the stored conditions. In the internal combustion engine having the in-cylinder injector and the intake manifold injector, the fuel injection mode is added to the above-described operating condition at the time of abnormality detection. (Injection ratio) is stored, the operation conditions are the same as or similar to the operation conditions stored when the abnormality is detected, and the current fuel injection mode is the same as or previously stored in the fuel injection mode stored when the abnormality is detected. The normal return determination is carried out when it is within the set predetermined range (spout distribution range) (see, for example, Patent Document 1).

JP 2011-026961 A

  By the way, in the internal combustion engine provided with the in-cylinder injector and the intake manifold injector, when an abnormality is detected in the injection mode (DUAL mode), for example, the injection ratio is stored, and the stored injection A normal range is determined by setting a predetermined range (spraying range) for the division rate. However, the injection ratio in the injection mode varies depending on the operating state of the internal combustion engine (ignition delay angle, load factor, etc.). It is difficult to consider that the conditions up to (within the range) are the same (similar) conditions as when an abnormality was detected. For this reason, it is inevitably impossible to accurately define the spray distribution range in which normal determination can be performed. If the spraying range cannot be accurately defined, the accuracy of normal return determination may be reduced.

  In addition, a method of performing the normal return determination only when the current injection ratio completely coincides with the injection ratio at the time of detecting an abnormality is conceivable. In this case, however, opportunities for normal determination are reduced.

  The present invention has been made in consideration of such circumstances, and can increase the chances of normal return determination in the injection mode (DUAL mode), and can accurately perform normal return determination. An object of the present invention is to provide an engine determination device.

  The present invention includes an in-cylinder fuel injection valve (in-cylinder injection injector) that directly injects fuel into the combustion chamber, and an intake passage fuel injection valve (port injection injector) that injects fuel into the intake passage. In-cylinder injection mode in which fuel is injected only from the in-cylinder fuel injection valve, port injection mode in which fuel is injected only from the fuel injection valve for intake passage, fuel injection valve for in-cylinder and fuel injection for intake passage In an internal combustion engine that can be selectively switched to any one of the fuel injection modes in which fuel is injected from the valve, the operating state of the internal combustion engine at the time of abnormality detection and the fuel injection mode are stored, It is premised on a determination device that performs normal return determination under a predetermined condition (predetermined similar operation condition) set based on the operation state at the time of detecting the abnormality and the fuel injection mode. In such an internal combustion engine determination device, when the fuel injection mode at the time of abnormality detection is the injection mode, normal determination is performed to determine normality under similar operating conditions that do not include the injection ratio in the injection mode. And a normal determination for determining normality in each of the in-cylinder injection mode and the port injection mode.

  The operation of the present invention will be described below.

  First, in the present invention, the normal return determination condition (similar operation condition) in the injection mode does not include the injection ratio, so the chance of normal determination in the injection mode can be increased. Here, there is a case where the normal return determination in the spray division mode cannot be performed accurately unless the spray distribution rate in the spray distribution mode is included in the normal return determination condition.

  For example, when the injection ratio in the injection mode (PFI injection ratio: KPFI) is 30% (DI: PFI = 7: 3), the injection amount of the in-cylinder injector is influenced by the air-fuel ratio. Since it is large, when there is an abnormality in the in-cylinder injector, a fuel system abnormality or misfire abnormality is detected. On the other hand, when the injection ratio is 50% (DI: PFI = 5: 5), the influence of the injection amount of the in-cylinder injector is small and the degree of abnormality is reduced. Even if there is an abnormality in the injector, a fuel system abnormality or misfiring abnormality may not be detected and a normal determination may be made. Therefore, in order to accurately perform the normal return determination in the injection mode, it is necessary to include the injection ratio in the determination condition. However, as described above, it is not possible to accurately define the injection range in which the normal determination can be performed. There are challenges.

  Accordingly, in the present invention, in addition to normal determination (normal determination of the fuel system and normal determination of the combustion state) performed under similar operation conditions that do not include the injection ratio in the injection mode, in the in-cylinder injection mode and the port injection Normal determination (normal determination of fuel system and normality of combustion state) is performed in each mode. Thus, in addition to the normal determination in the injection mode, it is possible to eliminate the influence of the injection ratio by separately determining that the in-cylinder injector and the port injection injector are normal. Therefore, it is possible to ensure the accuracy of the normal return determination in the spray mode only under similar operation conditions (conditions not including the spray rate).

  As described above, according to the present invention, it is possible to ensure both an opportunity for normal return determination in the ejection mode and an accuracy of normal return determination.

  As a specific configuration of the present invention, when the fuel injection mode at the time of detecting the abnormality is the injection mode (DUAL mode), the normality of the fuel system is set under similar operating conditions not including the injection rate in the injection mode. A configuration in which normal determination is performed and normal determination for determining normality of the fuel system in the in-cylinder injection mode and the port injection mode can be given.

  As another configuration, when the fuel injection mode at the time of detecting the abnormality is the injection mode (DUAL mode), the combustion state is normal under similar operating conditions not including the injection ratio in the injection mode. And a normal determination for determining whether the combustion state is normal in the in-cylinder injection mode and the port injection mode.

  In the present invention, the “fuel system” means a fuel system such as an injector, a fuel pump (feed pump, high pressure pump), an air-fuel ratio sensor (oxygen sensor), an air flow meter, etc. “Normal” means, for example, a case where an air-fuel ratio feedback correction amount described later is not an abnormal value. Moreover, “the combustion state is normal” means, for example, a combustion state without misfire.

  According to the present invention, when the fuel injection mode at the time of abnormality detection is the injection mode, the normal determination for determining normality under similar operation conditions not including the injection ratio in the injection mode and the in-cylinder injection mode In addition, since the normal determination for determining normality is performed in the port injection mode, it is possible to ensure both the opportunity for normal return determination in the ejection mode and the accuracy of the normal return determination.

It is a schematic block diagram which shows an example of the engine (internal combustion engine) to which this invention is applied. It is a block diagram which shows the structure of control systems, such as ECU. It is a figure which shows an example of a fuel-injection mode map. It is a flowchart which shows an example of the normal return determination process which ECU performs. It is a flowchart which shows an example of the normal return determination process which ECU performs. It is a flowchart which shows the other example of the normal return determination process which ECU performs. It is a flowchart which shows the other example of the normal return determination process which ECU performs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Engine-
FIG. 1 is a diagram showing a schematic configuration of an engine to which the present invention is applied. FIG. 1 shows only the configuration of one cylinder of the engine.

  The engine 1 of this example is a four-cylinder (first cylinder # 1 to fourth cylinder # 4) gasoline engine mounted on a vehicle, and reciprocates vertically in a cylinder block 1a constituting each cylinder. A moving piston 1c is provided. The piston 1c is connected to the crankshaft 15 via the connecting rod 16, and the reciprocating motion of the piston 1c is converted into rotation of the crankshaft 15 by the connecting rod 16.

  A signal rotor 17 is attached to the crankshaft 15. A plurality of teeth (protrusions) 17a are provided on the outer periphery of the signal rotor 17 at equal angles (in this example, for example, 10 ° CA (crank excessive)). Further, the signal rotor 17 has a missing tooth portion 17b in which two teeth 17a are missing.

  A crank position sensor (engine speed sensor) 201 for detecting a crank angle is disposed near the side of the signal rotor 17. The crank position sensor 201 is, for example, an electromagnetic pickup, and generates a pulse signal (voltage pulse) corresponding to the teeth 17a of the signal rotor 17 when the crankshaft 15 rotates. The engine speed NE can be calculated from the output signal of the crank position sensor 201.

  The cylinder block 1a of the engine 1 is provided with a water temperature sensor 203 that detects the temperature of engine cooling water. A cylinder head 1b is provided at the upper end of the cylinder block 1a, and a combustion chamber 1d is formed between the cylinder head 1b and the piston 1c. A spark plug 3 is disposed in the combustion chamber 1 d of the engine 1. The ignition timing of the spark plug 3 is adjusted by the igniter 4. The igniter 4 is controlled by an ECU (Electronic Control Unit) 100.

  An oil pan 18 for storing lubricating oil (engine oil) is provided below the cylinder block 1 a of the engine 1. Lubricating oil stored in the oil pan 18 is pumped up by an oil pump (not shown) through an oil strainer that removes foreign matters during operation of the engine 1, and the piston 1 c, crankshaft 15, connecting rod 16, etc. It is supplied to each part of the engine and used for lubrication and cooling of each part. The lubricating oil supplied in this way is used for lubrication and cooling of each part of the engine, then returned to the oil pan 18 and stored in the oil pan 18 until it is pumped up again by the oil pump. .

  An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 d of the engine 1. A part of the intake passage 11 is formed by an intake port 11a and an intake manifold 11b. A part of the exhaust passage 12 is formed by an exhaust port 12a and an exhaust manifold 12b.

  In the intake passage 11, an air cleaner 7 that filters intake air (fresh air), an air flow meter 204, an intake air temperature sensor 207, a throttle valve 5 for adjusting the intake air amount of the engine 1, and the like are arranged. The air flow meter 204 detects the intake air amount (new air amount). The intake air temperature sensor 207 detects the temperature of the air taken into the engine 1 (intake air temperature).

  The throttle opening of the throttle valve 5 is driven and controlled by the ECU 100. Specifically, the optimum intake air amount (in accordance with the operating state of the engine 1 such as the engine speed NE calculated from the output signal of the crank position sensor 201 and the accelerator pedal depression amount (accelerator opening) of the driver). The throttle opening of the throttle valve 5 is controlled so as to obtain a target intake air amount. More specifically, the actual throttle opening of the throttle valve 5 is detected using the throttle opening sensor 205, and the actual throttle opening coincides with the throttle opening (target throttle opening) at which the target intake air amount can be obtained. Thus, the throttle motor 6 of the throttle valve 5 is feedback controlled. Such a control system for the throttle valve 5 is referred to as an “electronic throttle system”, and it is also possible to control the throttle opening independently of the driver's accelerator pedal operation during idling operation or the like. .

  An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1d. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1d are communicated or blocked. Further, an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1d. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1d are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft 21 and the exhaust camshaft 22 to which the rotation of the crankshaft 15 is transmitted via a timing chain or the like.

  In the vicinity of the intake camshaft 21, a cam position sensor 202 is provided that generates a pulse signal when the piston 1c of a specific cylinder (for example, the first cylinder # 1) reaches the compression top dead center (TDC). ing. The cam position sensor 202 is, for example, an electromagnetic pickup, and is disposed so as to face one tooth (not shown) on the outer peripheral surface of the rotor provided integrally with the intake camshaft 21. When the shaft 21 rotates, a pulse signal (voltage pulse) is output. Since the intake camshaft 21 (and the exhaust camshaft 22) rotates at a half speed of the crankshaft 15, the cam position sensor 202 is set to 1 every time the crankshaft 15 rotates twice (720 ° rotation). Two pulse signals are generated.

  From the output signals of the cam position sensor 202 and the crank position sensor 201, the piston position (intake stroke / compression) of each cylinder (first cylinder # 1 to fourth cylinder # 4) of the engine 1 during engine operation. Stroke, explosion stroke, and exhaust stroke) can be recognized, and engine operation control such as precise fuel injection control and ignition timing control can be performed.

On the other hand, a three-way catalyst 9 is disposed in the exhaust passage 12. In the three-way catalyst 9, oxidation of CO and HC and reduction of NOx in the exhaust gas exhausted from the combustion chamber 1d to the exhaust passage 12 is performed, and these are made harmless CO ₂ , H ₂ O, and N ₂ . In this way, the exhaust gas is purified.

An air-fuel ratio (A / F) sensor 209 is disposed in the exhaust passage 12 upstream of the three-way catalyst 9 (upstream of the exhaust flow). The air-fuel ratio sensor 209 is a sensor that exhibits linear characteristics with respect to the air-fuel ratio. Further, an O ₂ sensor 210 is disposed in the exhaust passage 12 on the downstream side of the three-way catalyst 9. The O ₂ sensor 210 generates an electromotive force according to the oxygen concentration in the exhaust gas. When the output is higher than a voltage (comparison voltage) corresponding to the stoichiometric air-fuel ratio, the O ₂ sensor 210 determines that it is rich. When the output is lower than the comparison voltage, it is determined as lean.

<Fuel injection system>
Next, the fuel injection system of the engine 1 will be described.

  Each cylinder of the engine 1 is provided with an in-cylinder injector (in-cylinder fuel injection valve) 2a capable of directly injecting fuel into each combustion chamber 1d. These in-cylinder injectors 2a are connected to a common high-pressure fuel delivery pipe 20a.

  Further, in the intake passage 11 of the engine 1, a port injector (intake passage fuel injection valve) 2b capable of injecting fuel into each intake port 11a is disposed. The port injector 2b is provided for each cylinder. These port injectors 2b are connected to a common low pressure fuel delivery pipe 20b.

  Fuel supply to the high-pressure fuel delivery pipe 20a and the low-pressure fuel delivery pipe 20b is performed by a feed pump 301 and a high-pressure pump 302 as low-pressure pumps. The feed pump 301 pumps up fuel (gasoline etc.) in the fuel tank 300 and supplies it to the delivery pipe 20b for low pressure fuel and the high pressure pump 302. The high pressure pump 302 pressurizes the low pressure fuel from the feed pump 301 and supplies it to the high pressure fuel delivery pipe 20a.

  The in-cylinder injector 2a is an electromagnetically driven on-off valve that opens when a predetermined voltage is applied and injects fuel directly into the combustion chamber 1d. The opening / closing (injection time / injection timing) of the in-cylinder injector 2a is duty-controlled by the ECU 100.

  Similarly, the port injector 2b is an electromagnetically driven on-off valve that opens when a predetermined voltage is applied and injects fuel into the intake port 11a. The port injection injector 2b is also duty-controlled by the ECU 100 for opening and closing (injection time / injection timing).

  The injection ratio (PFI injection ratio: KPFI) between the fuel injection (DI injection) by the in-cylinder injector 2a and the fuel injection (PFI injection) by the port injector 2b will be described later.

  An air-fuel mixture (fuel + air) is formed in the combustion chamber 1b by fuel injection from one or both of the in-cylinder injector 2a and the port injector 2b. This air-fuel mixture is ignited by the spark plug 3 and burns and explodes. The piston 1c is reciprocated by the high-temperature and high-pressure combustion gas generated at this time, the crankshaft 15 is rotated, and the driving force (output torque) of the engine 1 is obtained. The combustion gas burned in the combustion chamber 1d is discharged to the exhaust passage 12 when the exhaust valve 14 is opened.

-ECU-
As shown in FIG. 2, the ECU 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a backup RAM 104, a counter 110, and the like.

  The ROM 102 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 101 executes various arithmetic processes based on various control programs and maps stored in the ROM 102. The RAM 103 is a memory that temporarily stores calculation results of the CPU 101, data input from each sensor, and the like. The backup RAM 104 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory. The counter 110 will be described later.

  The CPU 101, the ROM 102, the RAM 103, the backup RAM 104, and the counter 110 are connected to each other via the bus 107, and are connected to the input interface 105 and the output interface 106.

The input interface 105 includes a crank position sensor (engine speed sensor) 201, a cam position sensor 202, a water temperature sensor 203, an air flow meter 204, a throttle opening sensor 205, and an accelerator that outputs a detection signal corresponding to the depression amount of the accelerator pedal. High pressure fuel fuel pressure sensor 211 that detects the pressure (fuel pressure) of the high pressure fuel supplied to the opening degree sensor 206, the intake air temperature sensor 207, the intake manifold pressure sensor 208, the air-fuel ratio sensor 209, the O ₂ sensor 210, and the in-cylinder injector 2a. Various sensors such as a low-pressure fuel fuel pressure sensor 212 for detecting the pressure (fuel pressure) of the low-pressure fuel supplied to the port injector 2b are connected. Further, an ignition switch 213 is connected to the input interface 105, and when the ignition switch 213 is turned on (IG-ON), cranking of the engine 1 by a starter motor (not shown) is started.

  In-cylinder injector 2a, port injector 2b, igniter 4 of spark plug 3, and throttle motor 6 of throttle valve 5 are connected to output interface 106.

  Then, the ECU 100 controls the following fuel injection amount control, ignition timing control of the ignition plug 3, and drive control (intake air amount control) of the throttle motor 6 of the throttle valve 5 based on the detection signals of the various sensors described above. Various controls of the engine 1 including the above are executed. Further, the ECU 100 executes the following “air-fuel ratio feedback control” and “normal return determination processing”.

  The internal combustion engine (engine) determination device of the present invention is realized by the program executed by the ECU 100 described above.

-Fuel injection amount control-
First, the fuel injection mode map shown in FIG. 3 is stored in the ROM 102 of the ECU 100.

  The fuel injection mode map of FIG. 3 is an experiment of fuel injection modes in consideration of fuel consumption (fuel consumption rate) characteristics and output characteristics using the engine speed NE indicating the operating state of the engine 1 and the load factor KL as parameters. The maps are adapted by simulation or the like, and the DI mode (in-cylinder injection mode) in which fuel is injected only by the in-cylinder injector 2a and the PFI mode (port injection) in which fuel is injected only by the port injector 2b. Mode) and a dual mode (injection division (DI + PFI) mode) in which fuel is injected by the in-cylinder injector 2a and the port injector 2b.

  In the map of FIG. 3, in the dual mode, it is also possible to obtain the injection division rate KPFI (PFI injection division rate) using the engine speed NE and the engine load factor KL.

  The ECU 100 obtains the fuel injection mode with reference to the map of FIG. 3 based on the engine speed NE and the engine load factor KL obtained from the output signal of the crank position sensor 201, and determines the fuel injection mode and the required injection amount. The fuel injection is executed by calculating the injection time and the injection timing based on the above.

  Specifically, when the engine operating state (engine speed NE / load factor KL) is in the DI mode (injection division rate KPFI = 0%), the DI required injection amount and the output signal of the fuel pressure sensor 211 for high-pressure fuel Based on the obtained fuel pressure and the capacity (flow rate size) of the in-cylinder injector 2a, the DI injection time and DI injection timing of the high-pressure fuel injected from the in-cylinder injector 2a are calculated, and the calculated DI injection Based on the time and DI injection timing, the in-cylinder injector 2a is controlled to open and close to perform fuel injection.

  When the engine operation state (engine speed NE / load factor KL) is in the PFI mode (injection ratio KPFI = 100%), the required fuel injection amount, the fuel pressure obtained from the output signal of the low-pressure fuel pressure sensor 212, and The PFI injection time and the PFI injection timing of the low-pressure fuel injected from the port injector 2b are calculated based on the capacity (flow rate size) of the port injector 2b, and the calculated PFI injection time and PFI injection timing are calculated. Based on this, the port injection injector 2b is controlled to open and close to perform fuel injection.

  In-cylinder injection based on the injection ratio KPFI obtained from the map of FIG. 3 when the engine operating state (engine speed NE / load factor KL) is in the dual mode (0% <injection ratio KPFI <100%). DI required injection amount (total required injection amount x (1-injection distribution rate KPFI / 100)) of the injector 2a and port injector 2b PFI required injection amount (total required injection amount x injection ratio KPFI / 100) In the same manner as described above, the DI injection time and DI injection timing, and the PFI injection time and PFI injection timing are calculated. The in-cylinder injector 2a is controlled to open and close based on the calculated DI injection time and DI injection timing, and the port injection injector 2b is controlled to open and close based on the calculated PFI injection time and PFI injection timing. Perform injection.

  Here, the required injection amount is the amount of fuel in which the air-fuel ratio of the air-fuel mixture combusted in the engine 1 becomes the stoichiometric air-fuel ratio, and is, for example, in the engine operating state (engine speed NE and engine load factor KL). Based on this, it can be calculated using a map or the like. Further, the engine load factor KL uses a map or the like based on, for example, the engine rotational speed NE, the intake air amount obtained from the output signal of the air flow meter 204, the throttle opening obtained from the output signal of the throttle opening sensor 205, and the like. Can be calculated.

-Air-fuel ratio feedback control-
The ECU 100 sets the fuel injection amount so that the actual air-fuel ratio obtained from the outputs of the air-fuel ratio sensor 209 and the O ₂ sensor 210 disposed in the exhaust passage 12 of the engine 1 matches the target air-fuel ratio (for example, the theoretical air-fuel ratio). “Air-fuel ratio feedback control” to be controlled is executed. Specific processing of the air-fuel ratio feedback control will be described.

First, the three-way catalyst 9 disposed in the exhaust passage 12 of the engine 1 functions to oxidize unburned components (HC, CO) and reduce nitrogen oxides (NOx) at the same time when the air-fuel ratio is substantially the stoichiometric air-fuel ratio. To demonstrate. Furthermore, the three-way catalyst 9 has a function of storing oxygen (oxygen storage function, O ₂ storage function). Even if the air-fuel ratio shifts from the stoichiometric air-fuel ratio to a certain extent by this oxygen storage function, HC, CO and NOx can be purified. That is, when the air-fuel ratio of the engine 1 is lean and the gas flowing into the three-way catalyst 9 contains a large amount of NOx, the three-way catalyst 9 deprives the NOx of oxygen molecules and occludes these oxygen molecules and stores NOx. Reduce, thereby purifying NOx. Further, when the air-fuel ratio of the engine 1 becomes rich and the gas flowing into the three-way catalyst 9 contains a large amount of HC and CO, the three-way catalyst 9 gives oxygen molecules stored therein to oxidize, This purifies HC and CO.

  Therefore, in order for the three-way catalyst 9 to efficiently purify a large amount of continuously flowing HC and CO, the three-way catalyst 9 must store a large amount of oxygen. In order to efficiently purify a large amount of NOx that flows in, the three-way catalyst 9 needs to be in a state where it can sufficiently store oxygen. As is clear from the above, the purification capacity of the three-way catalyst 9 depends on the maximum amount of oxygen that can be stored by the three-way catalyst 9 (maximum oxygen storage amount).

  On the other hand, the three-way catalyst 9 deteriorates due to poisoning due to lead, sulfur, etc. contained in the fuel, or heat applied to the catalyst, and the maximum oxygen storage amount gradually decreases accordingly. Even when the maximum oxygen storage amount is reduced in this way, in order to maintain the emission satisfactorily, the air-fuel ratio of the gas discharged from the three-way catalyst 9 is in a state that is very close to the stoichiometric air-fuel ratio. Need to control.

Therefore, in this embodiment, feedback control of the fuel injection amount is performed based on the output signals of the air-fuel ratio sensor 209 and the O ₂ sensor 210 so that the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 9 becomes the stoichiometric air-fuel ratio. (Air-fuel ratio feedback control) Specifically, the following main feedback control and sub feedback control are executed.

(Main feedback control)
In the main feedback control, a feedback value (main F / B correction amount) to be reflected in the calculation of the fuel injection amount is calculated based on the deviation between the output signal of the air / fuel ratio sensor 209 and the stoichiometric air / fuel ratio (stoichiometric air / fuel ratio). The fuel injection amount is increased or decreased. Specifically, when the actual air-fuel ratio obtained from the output signal of the air-fuel ratio sensor 209 is richer than the stoichiometric air-fuel ratio (stoichiometric air-fuel ratio), the fuel injection amount is corrected to decrease, and the actual air-fuel ratio becomes the stoichiometric air-fuel ratio. If it is leaner than the fuel ratio, the fuel injection amount is corrected to increase.

  In the present embodiment, when the main feedback correction amount (the air-fuel ratio learning value indicating the deviation from the stoichiometric air-fuel ratio) is equal to or greater than a predetermined value (abnormal value), a fuel system abnormality or a misfire abnormality has occurred. Determine (abnormality detection). More specifically, for example, in the main feedback control, the main feedback correction amount (main F / B correction amount) is limited within a predetermined guard range, and the main F / B correction amount is If the upper limit guard value or the lower limit guard value of the guard range is stuck to a predetermined time (abnormality detection time: 10 sec), for example, it is determined that the fuel system is abnormal or misfiring is abnormal.

  In the present embodiment, when the abnormality is detected, the operation conditions (engine speed NE, load factor KL, warm-up state (cold / high temperature)) when the abnormality is detected, and the fuel injection mode ( DI injection, PFI injection, or DUAL injection) is stored in the RAM 103 of the ECU 100, for example.

  The guard range that limits the main F / B correction amount is a range that has been adapted in advance through experiments and calculations in consideration of, for example, an abnormality (incorrect correction) of the main F / B correction amount (for example, a stoichiometric sky). The range of ± 30% with respect to the fuel ratio) is set.

(Sub feedback control)
In the sub-feedback control, a feedback value (sub F / B correction amount) to be reflected in the calculation of the fuel injection amount is calculated based on the deviation between the output voltage of the O ₂ sensor 210 and the comparison voltage (stoichiometric equivalent value). Then, by correcting the output of the air-fuel ratio sensor 209 based on the sub F / B correction amount, the air-fuel ratio upstream of the three-way catalyst 9 matches the stoichiometric air-fuel ratio. For the sub F / B correction amount, the same processing as that for the main F / B correction amount described above may be executed within the guard range. In this case, the fuel system abnormality or misfire abnormality may be determined using the sub F / B correction amount.

-Normal return judgment processing-
First, in the engine 1 provided with the in-cylinder injector 2a and the port injector 2b, as described above, when an abnormality is detected in the dual mode, the injection ratio is stored and stored. Although the normal return determination is performed by setting a predetermined range (spout distribution range) for the spray distribution ratio, it is not possible to accurately define the spray distribution range in which normal determination can be performed. In other words, since the injection ratio in the dual mode varies depending on the operating state of the engine 1 (ignition delay angle, load ratio, etc.), it is within what range (what percentage range) with respect to the injection ratio at the time of abnormality detection. It is difficult to consider that the conditions up to (inside) are the same (similar) conditions as those at the time of abnormality detection, and it is not possible to accurately define the spray distribution range in which normal determination can be performed. In addition, a method of performing the normal return determination only when the current injection ratio completely coincides with the injection ratio at the time of detecting an abnormality is conceivable. In this case, however, opportunities for normal determination are reduced.

  In consideration of such points, in the present embodiment, it is possible to increase opportunities for normal determination in the dual mode, and to ensure accuracy of normal return determination. An example of specific processing (normal return determination processing) for realizing this will be described with reference to the flowcharts of FIGS. The processing routines of FIGS. 4 and 5 are repeatedly executed by the ECU 100 every predetermined time (for example, every several msec).

  Here, in the present embodiment, the operation state of the target engine 1 is the engine speed NE, the load factor KL, and the warm-up state. Further, the warm-up state is set to one of a cold state (a state where the water temperature is lower than the warm-up temperature (for example, 80 ° C.)) and a high temperature (a state where the water temperature is equal to or higher than the warm-up temperature).

  In this embodiment, a DI normal counter, a PFI normal counter, and a fuel system normal counter are used as the counter 110 (see FIG. 2). Each of these DI normal counter, PFI normal counter, and fuel system normal counter is a timer counter that counts up the time.

  When the processing routine of FIG. 4 and FIG. 5 is started, first, in step ST101 shown in FIG. 4, abnormality detection (detection of fuel system abnormality or misfiring abnormality) has been performed before, and the operation of the engine 1 at the time of the abnormality detection is performed. It is determined whether the state (engine speed NE, load factor KL, warm-up state (cold / high temperature)) and fuel injection mode are stored. When the determination result of step ST101 is negative (NO) (when there is no memory of the operating state / fuel injection mode), the process returns.

  If the determination result of step ST101 is affirmative (YES), the process proceeds to step ST102. In step ST102, it is determined whether or not the fuel injection mode stored when the abnormality is detected is the dual mode. If the determination result is negative (NO), the processing returns after executing the processing of step ST140 (DI normal counter clear, PFI normal counter clear) shown in FIG.

  If the determination result in step ST102 is affirmative (YES) (when the abnormality detection fuel injection mode is the dual mode), the process proceeds to step ST111.

  In step ST111, all three conditions of “the current fuel injection mode is the DI mode”, “DI normal / not determined”, and “the main F / B correction amount is not an abnormal value” are satisfied. It is determined whether or not. If the determination result is a negative determination (NO) (if any one of the above three conditions is not satisfied), the DI normal counter is cleared (step ST113) and the process proceeds to step ST114. .

  If the determination result in step ST111 is affirmative (YES) (when all of the above three conditions are satisfied), the DI normal counter starts counting up (time counting) (step ST112). This DI normal counter count-up (time keeping) is continued while the determination result of step ST111 is affirmative (YES), and is stopped when the determination result of step ST111 is negative (NO).

  Next, in step ST114, it is determined whether the count value (time value) of the DI normal counter has reached a predetermined value. If the determination result is affirmative (YES) (when [DI normal counter count value ≧ predetermined value]), the DI normal flag is set to ON in step ST115, and the process proceeds to step ST121. If the determination result in step ST114 is negative (NO) (when the count value of the DI normal counter <predetermined value), the process proceeds to step ST121 without performing flag processing.

  Here, the predetermined value used for the determination process in step ST114 is a time (for example, 10 sec) corresponding to the “abnormality detection time” described in the “main feedback control” described above, and the state in which step ST111 is affirmative is determined. If the predetermined value (abnormality detection time) is continued, the in-cylinder injector 2a can be determined to be normal. The predetermined value may be a value other than “10 sec”.

  In step ST121, all three conditions of “the current fuel injection mode is the PFI mode”, “PFI normal / unjudged”, and “the main F / B correction amount is not an abnormal value” are satisfied. It is determined whether or not. If the determination result is a negative determination (NO) (if any one of the above three conditions is not satisfied), the PFI normal counter is cleared (step ST123) and the process proceeds to step ST124. .

  If the determination result in step ST121 is affirmative (YES) (when all three conditions are satisfied), the PFI normal counter starts counting up (time counting) (step ST122). The count-up (time keeping) of the PFI normal counter is continued while the determination result of step ST121 is affirmative (YES), and is stopped when the determination result of step ST121 is negative (NO).

  Next, in step ST124, it is determined whether or not the count value (time value) of the PFI normal counter has reached a predetermined value. If the determination result is affirmative (YES) (if PFI normal counter count value ≧ predetermined value), the PFI normal flag is set to ON in step ST125, and the process proceeds to step ST130 in FIG. . If the determination result in step ST124 is negative (NO) (when the count value of the PFI normal counter <predetermined value), the process proceeds to step ST130 in FIG. 5 without performing flag processing.

  Here, the predetermined value used in the determination process of step ST124 is a time (for example, 10 sec) corresponding to the “abnormality detection time” described in the above “main feedback control”, and the state where step ST121 is an affirmative determination. If the predetermined value (abnormality detection time) is continued, the port injection injector 2b can be determined to be normal. The predetermined value may be a value other than “10 sec”.

  In step ST130 shown in FIG. 5, all of the following similar operating conditions (j1) to (j4) are performed using the engine speed NE, the load factor KL, the warm-up state, and the fuel injection mode stored at the time of detecting the abnormality. It is determined whether it is established. Note that this step ST130 is executed when the fuel injection mode stored at the time of detecting an abnormality is a dual injection (when the determination at step ST102 is affirmative), the “fuel injection at the time of detecting an abnormality” in the following condition (j4): The “mode” is “DUAL injection”.

(J1) NE-375 rpm at abnormality detection ≦ current NE ≦ NE + 375 rpm at abnormality detection
(J2) KL−20% at abnormality detection ≦ current KL ≦ KL at abnormality detection + 20%
(J3) Warm-up state at abnormality detection = Current warm-up state (j4) Fuel injection mode at abnormality detection = Current fuel injection mode If the determination result in step ST130 is affirmative (YES), the process proceeds to step ST131. In step ST131, it is determined whether or not the correction amount (F / B correction amount) of the main feedback control described above is not an abnormal value. If the determination result is affirmative (YES), the fuel system normal counter starts counting up (time counting) (step ST132), and the process proceeds to step ST134. The counting up (time keeping) of the fuel system normal counter is continued while both the determination results of step ST130 and step ST131 are affirmative (YES), and the determination result of either step ST130 or step ST131 is negative. It stops when it becomes (NO).

  If the determination result in step ST130 is negative (NO), or if the determination result in step ST131 is negative (NO), the fuel system normal counter is cleared (step ST133), and the process proceeds to step ST134. move on.

  In step ST134, it is determined whether or not the count value (time value) of the fuel system normal counter has reached a predetermined value. If the determination result is affirmative (YES) (when [the count value of the fuel system normal counter ≧ predetermined value)], in step ST135, the dual-time fuel system normal flag is set to ON and the process proceeds to step ST136. . If the determination result in step ST134 is negative (NO) (when the count value of the fuel system normal counter <predetermined value), the process proceeds to step ST136 without performing flag processing.

  Here, the predetermined value set with respect to the count value (time value) of the fuel system normal counter is a time for determining whether the fuel system is normal during DUAL, and there is a state where both steps ST130 and ST140 are positive determinations. If it continues for more than this predetermined value (determination time), it can be determined that the dual fuel system is normal. The predetermined value may be a fixed value (for example, 10 sec), or may be set variably according to the operating state of the engine 1.

  In step ST136, it is determined whether or not all of the DUAL-time fuel system normal flag, DI normal flag, and PFI normal flag are ON. If the determination result is affirmative (YES), In ST137, it is determined that the fuel system is normal (normal return determination). On the other hand, if the determination result of step ST136 is negative (NO), the process returns.

  As described above, according to the present embodiment, since the injection ratio is not included in the conditions for normal return determination (similar operation conditions) in the DUAL mode, the opportunities for normal determination in the DUAL mode can be increased. Moreover, in addition to normal determination in the dual mode (normal determination of fuel system), normal determination (normal determination of fuel system) is performed in the in-cylinder injection mode and in the port injection mode, respectively. It can be individually determined that the injector 2a and the port injector 2b are normal. As a result, the influence of the injection ratio can be eliminated, so that the normal return determination in the DUAL mode can be accurately performed only under similar operation conditions (conditions not including the injection ratio).

  As described above, in the present embodiment, it is possible to ensure both the opportunity for normal return determination in the dual mode and the accuracy of the normal return determination.

-Other examples of normal return judgment processing-
Next, another example of normal return determination processing will be described.

  First, in this example, the ECU 100 is configured to execute misfire detection processing. The misfire detection process will be described below.

  When a misfire occurs in a cylinder (for example, the first cylinder # 1) among the four cylinders # 1 to # 4 of the engine 1, the engine rotation speed in the explosion stroke of that cylinder (including a plurality of cylinders) is Therefore, the time required for the crankshaft 15 to rotate at a constant crank angle during the explosion stroke of the cylinder (first cylinder # 1) where the misfire has occurred is reduced to other cylinders (for example, the second cylinder # 2 to the second cylinder # 2). It becomes longer than the time during the explosion stroke of 4 cylinder # 4). Therefore, it is possible to recognize the occurrence of misfire by measuring and comparing these times.

  An example of the specific processing will be described.

  First, the ECU 100 takes in the output signals of the crank position sensor (engine speed sensor) 201 and the cam position sensor 202 at every predetermined crank angle (for example, every 30 ° CA), and based on these signals, the first When the cylinder # 1 is in the explosion stroke, the elapsed time T1 required for the crankshaft 15 to rotate at a constant crank angle (for example, 180 ° CA) during the explosion stroke, and the explosion stroke of the first cylinder # 1 Elapsed time required for the crankshaft 15 to rotate at a certain crank angle (for example, 180 ° CA) during the explosion stroke of the second cylinder # 2 that has reached the explosion stroke one time before (360 ° CA). The difference from T2 is calculated to obtain the rotation fluctuation amount ΔNE1 (= T1−T2) of the first cylinder # 1.

  Similarly, the elapsed time T3 (third cylinder # 3) required for the crankshaft 15 to rotate at a constant crank angle (for example, 180 ° CA) during the explosion stroke of the cylinders # 2 to # 4 of the engine 1 is the same. , T4 (fourth cylinder # 4), T2 (second cylinder # 2) are sequentially calculated, and the third cylinder # 3 rotational fluctuation amount ΔNE3 (= T3−T1), the fourth cylinder # 4 rotational fluctuation amount. ΔNE4 (= T4-T3) and the rotational fluctuation amount ΔNE2 (= T2-T4) of the second cylinder # 2 are obtained.

  Then, the ECU 100 compares the rotational fluctuation amounts ΔNE1 to ΔNE4 of the cylinders # 1 to # 4 obtained by the above calculation with the misfire determination threshold value, and when there is a cylinder in which the rotational fluctuation amount ΔNE exceeds the misfire determination threshold value. Detects that a misfire has occurred. Each time the rotational fluctuation amount ΔNE exceeds the misfire determination threshold, any one of a misfire counter at the time of DI, a misfire counter at PFI, or a misfire counter when a similar condition is met is It is incremented by one according to the fuel injection mode.

  Here, the misfire determination threshold value set with respect to the rotational fluctuation amount ΔNE is a value that is empirically adapted based on the result obtained by experimentally / simulating the rotational fluctuation amount of the engine 1 in which misfire occurs. It is. This misfire determination threshold value is stored in the ROM 102 of the ECU 100. Further, the misfire determination threshold value may be variably set according to the rotational fluctuation amount ΔNE or the like. The rotational fluctuation amount of each cylinder # 1 to # 4 may be recognized (calculated) by other known methods.

Further, the method of detecting misfire of the engine 1 is not limited to the method of detecting misfire using the rotation fluctuation amount of the engine 1 described above. For example, an air-fuel ratio sensor and O ₂ arranged before and after the catalyst are used. Other known methods such as a method of detecting the occurrence of misfire based on an output signal (difference between two sensor detection values) with a sensor (oxygen sensor) may be adopted.

(Normal recovery judgment processing)
Next, another example of normal return determination processing will be described with reference to the flowcharts of FIGS. The processing routines of FIGS. 6 and 7 are repeatedly executed by the ECU 100 every predetermined time (for example, every several msec).

  Here, also in this example, the operation state of the target engine 1 is the engine speed NE, the load factor KL, and the warm-up state. Further, the warm-up state is set to one of a cold state (a state where the water temperature is lower than the warm-up temperature (for example, 80 ° C.)) and a high temperature (a state where the water temperature is equal to or higher than the warm-up temperature).

  In this example, as the counter 110 (see FIG. 2), the DI operation period counter, the PFI operation period counter, and the similar condition establishment period counter, the DI misfire counter, the PFI misfire counter, and the like The ECU 100 is provided with a misfire counter when the condition is satisfied.

(Period counter)
Each of the period counters is a counter that increments the count value by one each time the engine 1 (crankshaft 15) makes one revolution (1 Rev) from the count start time. This is a counter that measures the cumulative rotational speed (Rev) of the engine 1 from the start of operation in the mode, and the PFI operation period counter measures the cumulative rotational speed (Rev) of the engine 1 from the start of operation in the PFI mode. Counter. The similar condition satisfaction period counter is a counter that measures the cumulative number of revolutions (Rev) of the engine 1 from the time when a later-described similar condition is satisfied.

(Misfire counter)
The DI misfire counter is a counter that counts up (increments) by one each time the rotational fluctuation amount ΔNE of each cylinder # 1 to # 4 of the engine 1 exceeds the misfire determination threshold value during the DI mode. The PFI misfire counter is a counter that increments the count value by one each time the rotational fluctuation amount ΔNE of each cylinder # 1 to # 4 of the engine 1 exceeds the misfire determination threshold value during the PFI mode. The misfire counter when the similar condition is satisfied counts one count value each time the rotational fluctuation amount ΔNE of each cylinder # 1 to # 4 of the engine 1 exceeds the misfire determination threshold during a period in which the similar condition described later is satisfied. It is a counter to be up.

  Next, the flowcharts of FIGS. 6 and 7 will be described.

  When the processing routine of FIG. 6 and FIG. 7 is started, first, in step ST201 shown in FIG. 6, abnormality detection (detection of fuel system abnormality or misfire abnormality) has been performed before, and the operation of the engine 1 at the time of the abnormality detection is performed. It is determined whether the state (engine speed NE, load factor KL, warm-up state (cold / high temperature)) and fuel injection mode are stored. When the determination result in step ST201 is negative (NO) (when there is no storage of the operating state / fuel injection mode), the process returns.

  If the determination result of step ST201 is affirmative (YES), the process proceeds to step ST202. In step ST202, it is determined whether or not the fuel injection mode stored when the abnormality is detected is the dual mode. If the determination result is negative (NO), the process returns. If the determination result in step ST202 is affirmative (YES) (when the abnormality detection fuel injection mode is the dual mode), the process proceeds to step ST211.

  In step ST211, it is determined whether or not the current fuel injection mode is the DI mode. When the determination result is negative (NO) (when not in the DI mode), the process proceeds to step ST221. If the determination result in step ST211 is affirmative (YES) (DI mode), the process proceeds to step ST212. Here, in the DI mode, counting of the DI operation period counter is started from the time when the DI mode is entered, and every time the engine 1 (crankshaft 15) makes one rotation (1 Rev), the DI operation period counter is counted. The value is counted up one by one.

  In step ST212, it is determined whether or not a misfire is currently occurring in the misfire detection process. If the determination result is affirmative (YES), the DI misfire counter is incremented by one (step ST213), and the process proceeds to step ST214. If the determination result of step ST212 is negative (NO), the process proceeds to step ST214 without performing the count-up process.

  In step ST214, it is determined whether or not the count value (DI operation period) of the DI operation period counter has reached a predetermined value (for example, 200 Rev). When the determination result is negative (when [DI operation period <predetermined value]), the process proceeds to step ST221. When the determination result of step ST214 is affirmative (when [DI operation period ≧ predetermined value]), the process proceeds to step ST215.

  In step ST215, it is determined whether or not the count value of the DI misfire counter is smaller than a predetermined value (eg, “5”). If the determination result is affirmative (YES) ([DI misfire counter <predetermined value]), the DI normal flag is set to ON in step ST216, and the process proceeds to step ST221. If the determination result in step ST215 is negative (NO) (if DI misfire counter ≧ predetermined value), the process proceeds to step ST221 without performing flag processing.

  Here, the predetermined value used in the determination process of step ST215 is a misfire abnormality determination threshold value, and is a value that is adapted in advance through experiments and calculations. In this example, for example, the predetermined value is “5”, but other values may be used.

  In step ST221, it is determined whether or not the current fuel injection mode is the PFI mode. If the determination result is negative (NO) (when not in PFI mode), the process proceeds to step ST230 of FIG. If the determination result of step ST221 is affirmative (YES) (PFI mode), the process proceeds to step ST222. Here, in the PFI mode, counting of the PFI operation period counter is started from the time when the PFI mode is entered, and every time the engine 1 (crankshaft 15) makes one revolution (1 Rev), the PFI operation period counter is counted. The value is counted up one by one.

  In step ST222, it is determined whether the misfire detection process is currently misfired. If the determination result is affirmative (YES), the count value of the PFI misfire counter is incremented by one (step ST223), and the process proceeds to step ST224. If the determination result in step ST222 is negative (NO), the count-up process is not performed and the process proceeds to step ST224.

  In step ST224, it is determined whether or not the count value (PFI operation period) of the PFI operation period counter has reached a predetermined value (for example, 200 Rev). When the determination result is negative (when [PFI operation period <predetermined value]), the process proceeds to step ST230 of FIG. When the determination result of step ST224 is affirmative (when [PFI operation period ≧ predetermined value]), the process proceeds to step ST225.

  In step ST225, it is determined whether or not the count value of the PFI misfire counter is smaller than a predetermined value (eg, “5”). If the determination result is affirmative (YES) (if PFI misfire counter <predetermined value), the PFI normal flag is set to ON in step ST226, and the process proceeds to step ST230 of FIG. If the determination result in step ST215 is negative (NO) (if PFI misfire counter ≧ predetermined value), the process proceeds to step ST230 in FIG. 7 without performing flag processing.

  Here, the predetermined value used for the determination process in step ST225 is a misfire abnormality determination threshold value, which is a value that is adapted in advance through experiments and calculations. In this example, for example, the predetermined value is “5”, but other values may be used.

  In step ST230 of FIG. 7, all of the following similar operating conditions (j1) to (j4) are satisfied using the engine speed NE, the load factor KL, the warm-up state, and the fuel injection mode when the abnormality is detected. It is determined whether or not. Note that this step ST230 is executed when the fuel injection mode stored at the time of detecting an abnormality is a dual injection (when the determination at step ST202 is affirmative), the “fuel injection at the time of detecting an abnormality” in the following condition (j4) The “mode” is “DUAL injection”.

(J1) NE-375 rpm at abnormality detection ≦ current NE ≦ NE + 375 rpm at abnormality detection
(J2) KL−20% at abnormality detection ≦ current KL ≦ KL at abnormality detection + 20%
(J3) Warm-up state at abnormality detection = Current warm-up state (j4) Fuel injection mode at abnormality detection = Current fuel injection mode If the determination result in step ST230 is affirmative (YES), the process proceeds to step ST231. Here, when the similar operation condition is satisfied, the counting of the similar condition satisfaction period counter is started from the time when the similar operation condition is satisfied, and every time the engine 1 (crankshaft 15) makes one rotation (1 Rev), The count value of the similar condition satisfaction period counter is incremented by one.

  In step ST231, it is determined whether or not a misfire is currently occurring in the misfire detection process. If the determination result is affirmative (YES), the count value of the misfire counter when the similar operation condition is satisfied is incremented by 1 (step ST232), and the process proceeds to step ST233. If the determination result of step ST231 is negative (NO), the process proceeds to step ST233 without performing the count-up process.

  In step ST233, it is determined whether the count value (similar operation condition establishment period) of the similar condition establishment period counter has reached a predetermined value (for example, 1000 Rev). When the determination result is negative (when [similar operation condition establishment period <predetermined value]), the process proceeds to step ST236. When the determination result of step ST233 is affirmative (when [similar operation condition establishment period ≧ predetermined value]), the process proceeds to step ST234.

  In step ST234, it is determined whether or not the count value of the misfire counter when the similar operation condition is satisfied is smaller than a predetermined value (for example, “20”). If the result of the determination is affirmative (YES) ([if misfire counter when a similar operation condition is satisfied <predetermined value]), the DUAL misfire normal flag (there is no misfire and the combustion state is normal) in step ST235. Is set to ON, and the process proceeds to step ST236. When the determination result of step ST234 is negative determination (NO) (when [similar operation condition misfire counter ≧ predetermined value]), the process proceeds to step ST236 without performing flag processing.

  Here, the predetermined value used in the determination process in step ST234 is a misfire abnormality determination threshold value, and is a value that is adapted in advance through experiments and calculations. In this example, for example, the predetermined value is “20”, but other values may be used.

  In step ST236, it is determined whether all of the DUAL misfire normal flag, the DI normal flag, and the PFI normal flag are ON. If the determination result is affirmative (YES), step ST237 It is determined that the misfire is normal (combustion state is normal) (normal return determination). On the other hand, if the determination result of step ST136 is negative (NO), the process returns.

  As described above, according to this example, since the injection ratio is not included in the normal return determination condition (similar operation condition) in the DUAL mode, the opportunities for normal determination in the DUAL mode can be increased. Moreover, in addition to the normal determination in the dual mode (normal determination for determining that the combustion state is normal), the normal determination (determining that the combustion state is normal) in the in-cylinder injection mode and the port injection mode, respectively. Therefore, it can be individually determined that the in-cylinder injector 2a and the port injector 2b are normal. As a result, the influence of the injection division rate can be eliminated, so that the normal return determination in the DUAL mode can be accurately performed only under similar operation conditions (conditions not including the injection division rate).

  As described above, also in this embodiment, it is possible to both ensure the opportunity for normal return determination in the dual mode and ensure the accuracy of the normal return determination.

  In the above example, a predetermined value (predetermined value set for the count value of the DI operation period counter) used in the determination process in step ST214 in FIG. 6 and a predetermined value used in the determination process in step ST224 in FIG. The (predetermined value set for the count value of the PFI operation period counter) is “200 Rev”, but is not limited to this, and any other numerical value (Rev) may be set. In addition, a predetermined value (predetermined value set with respect to the count value of the similar operation condition establishment period counter) is set to “1000 Rev” in the determination process of step ST223 in FIG. 7. (Rev) may be set.

-Other embodiments-
In the above example, the case where the present invention is applied to a four-cylinder gasoline engine has been described. However, the present invention is not limited to this, and can be applied to a gasoline engine having any number of cylinders such as a six-cylinder gasoline engine. It is. In addition to the in-line multi-cylinder gasoline engine, the present invention can be applied to control of a V-type multi-cylinder gasoline engine.

  The present invention includes an in-cylinder fuel injection valve that directly injects fuel into a combustion chamber, and an intake passage fuel injection valve that injects fuel into an intake passage, and includes an in-cylinder injection mode (DI mode), a port injection mode ( The present invention can be effectively used for detecting an abnormality of an internal combustion engine (engine) that can be selectively switched to one fuel injection mode among a PFI mode) and an injection mode (DUAL mode).

1 Engine 1d Actual combustion 11 Intake passage 11a Intake port 2a In-cylinder injector (in-cylinder fuel injection valve)
2b Injector for port injection (fuel injection valve for intake passage)
100 ECU
103 RAM
110 counter 201 crank position sensor (engine speed sensor)
203 Water temperature sensor 204 Air flow meter 209 Air-fuel ratio sensor 210 O ₂ sensor

Claims (3)

An in-cylinder fuel injection valve that directly injects fuel into the combustion chamber and an in-cylinder fuel injection valve that injects fuel into the intake passage, and injects fuel only from the in-cylinder fuel injection valve. Any one of a mode, a port injection mode in which fuel is injected only from the fuel injection valve for intake passage, and an injection mode in which fuel is injected from the fuel injection valve for cylinder and the fuel injection valve for intake passage In an internal combustion engine that can be selectively switched to a fuel injection mode,
A determination device that stores an operation state and a fuel injection mode of an internal combustion engine at the time of detecting an abnormality, and performs a normal return determination under a predetermined condition set based on the operation state and the fuel injection mode,
When the fuel injection mode at the time of abnormality detection is the injection mode, the normal determination for determining normality under similar operation conditions not including the injection ratio in the injection mode, the in-cylinder injection mode and the port injection mode And determining whether the engine is normal. The determination apparatus for an internal combustion engine according to claim 1,
When the fuel injection mode at the time of abnormality detection is the injection mode, the normal determination for determining the normality of the fuel system under similar operation conditions not including the injection ratio in the injection mode, the in-cylinder injection mode and the port A determination apparatus for an internal combustion engine that performs normal determination for determining whether the fuel system is normal in the injection mode. The determination apparatus for an internal combustion engine according to claim 1,
When the fuel injection mode at the time of abnormality detection is the injection mode, normal determination for determining that the combustion state is normal under similar operation conditions not including the injection ratio in the injection mode, and in-cylinder injection mode A determination device for an internal combustion engine that performs normal determination for determining whether the combustion state is normal in each of the time and port injection modes.

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