JP2012167607A - Control apparatus for internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve exhaust emission and drivability at acceleration in an internal combustion engine including an in-cylinder fuel injection valve and a supercharger.SOLUTION: The internal combustion engine with the supercharger includes: the in-cylinder fuel injection valve for directly injecting fuel into a combustor chamber; an injection valve for an intake passage, the valve for injecting the fuel into the intake passage; and the supercharger for supercharging air suctioned into the combustion chamber. While an actual boost pressure rises to a target boost pressure at acceleration, uniformity of fuel-air mixture is enhanced to improve the efficiency of using air, by just performing fuel injection from an injector 2b for a port injection. As a result of the fuel injection control, smoke generation can be suppressed at acceleration and the exhaust emission can be improved.

Description

  The present invention relates to a control device for a supercharged internal combustion engine that includes a supercharger that supercharges air sucked into a combustion chamber.

  As an internal combustion engine (hereinafter also referred to as an engine) mounted on a vehicle or the like, a port injection type engine or an in-cylinder direct injection type engine is known.

  A port injection type engine injects fuel such as gasoline into an intake passage from a fuel injection valve (intake passage fuel injection valve) disposed in an intake port to form a homogeneous mixture, and the mixture is injected into a combustion chamber. This is an engine that is introduced and ignited by a spark plug.

  In-cylinder direct-injection engines have a fuel injection valve (in-cylinder fuel injection valve) in each cylinder, and fuel such as gasoline is directly injected into the combustion chamber from the fuel injection valve. This is an engine that mixes with introduced intake air to form an air-fuel mixture and ignites the air-fuel mixture with a spark plug. In an engine equipped with such an in-cylinder fuel injection valve, fuel is injected into the combustion chamber during the compression stroke of the internal combustion engine, and an air-fuel mixture having good ignitability is formed only in the vicinity of the spark plug at the ignition timing. The combustion chamber as a whole can realize the combustion of a lean air-fuel mixture, so-called stratified combustion.

  Some in-cylinder direct injection engines include a supercharger (hereinafter also referred to as a turbocharger) that uses exhaust energy (see, for example, Patent Document 1). In general, a turbocharger connects a turbine wheel that is rotated by exhaust gas flowing through an engine exhaust passage, a compressor impeller that forcibly feeds air in the intake passage to a combustion chamber of the engine, and the turbine wheel and the compressor impeller. Connecting shaft. In the turbocharger having such a structure, the turbine wheel disposed in the exhaust passage is rotated by the energy of the exhaust gas, and the compressor impeller disposed in the intake passage is rotated accordingly, whereby the intake air is supercharged, and the engine Supercharged air is forced into the combustion chamber of each cylinder.

  In addition, in an internal combustion engine (engine) provided with a cylinder fuel injection valve and a supercharger, the techniques described in Patent Documents 2 and 3 below are related to a technique for performing fuel injection control according to a supercharging pressure. is there.

JP 2001-214812 A Japanese Patent Laid-Open No. 04-203335 JP 11-351041 A

  By the way, in a cylinder direct injection type engine with a supercharger (an engine having only a cylinder fuel injection valve), smoke may be generated during acceleration and exhaust emission may deteriorate. That is, an engine having only an in-cylinder fuel injection valve is originally an engine having a low homogeneity of the air-fuel mixture. (Hereinafter referred to as smoke) may occur.

  The present invention has been made in view of such a situation, and an object of the present invention is to realize control capable of improving exhaust emission during acceleration in an internal combustion engine having an in-cylinder fuel injection valve and a supercharger. And

  The present invention includes an in-cylinder fuel injection valve that directly injects fuel into a combustion chamber, an intake passage fuel injection valve that injects fuel into an intake passage (such as an intake port), and air that is sucked into the combustion chamber. It is premised on a control device for an internal combustion engine with a supercharger provided with a supercharger for supplying, and in such a control device for an internal combustion engine with a supercharge, at the time of acceleration (when the internal combustion engine is accelerated), Fuel injection control means for performing only fuel injection from the intake passage fuel injection valve (port injection injector) until the supercharging pressure by the supercharger rises to the target supercharging pressure is provided. Is a technical feature.

  As a specific configuration of the present invention, based on the actual supercharging pressure recognition means for recognizing the actual supercharging pressure of the intake air supercharged by the supercharger and the operating state (for example, engine load) of the internal combustion engine. A target boost pressure setting means for setting a target boost pressure, and a target boost pressure recognized by the actual boost pressure recognition means during acceleration is set by the target boost pressure setting means. A configuration in which only fuel injection from the fuel injection valve for intake passage is executed until the boost pressure (target boost pressure during acceleration) is increased can be given.

  In this case, as a specific example of the actual supercharging pressure recognition means, a supercharging pressure sensor (intake manifold pressure sensor) disposed in the intake passage on the downstream side of the supercharger (compressor impeller) can be cited. Until the actual boost pressure obtained from the output of the boost pressure sensor (actual boost pressure during engine acceleration) rises to the target boost pressure, only fuel injection from the fuel injection valve for the intake passage is performed. Should be done.

  Further, in the present invention, as a method for determining the acceleration time, for example, when the amount of change per unit time of the accelerator opening (or throttle opening) is equal to or greater than a predetermined determination threshold, “acceleration time” The method of judging can be mentioned. Note that the acceleration determination threshold value may be set to an appropriate value by experiment / calculation in consideration of the target engine model.

  According to the present invention, the fuel injection valve for the intake passage (port injector) is used until the actual supercharging pressure rises to the target supercharging pressure during acceleration, that is, while the supercharging delay due to the turbo lag occurs. ), Only the fuel injection is performed, so that the homogeneity of the air-fuel mixture can be increased and the air utilization efficiency is increased. As a result, the generation of smoke during acceleration can be suppressed, and exhaust emission can be improved. Further, it is possible to increase the engine output torque during the delay in supercharging, and drivability can be improved.

  According to the present invention, in an internal combustion engine provided with an in-cylinder fuel injection valve and a supercharger, it is possible to suppress the generation of smoke during acceleration, so that exhaust emission can be improved.

It is a schematic block diagram which shows an example of the engine with a supercharger to which this invention is applied. It is a schematic block diagram which shows only 1 cylinder of the engine of FIG. It is a block diagram which shows the structure of control systems, such as ECU. It is a figure which shows an example of the injection division ratio map of fuel injection. It is a flowchart which shows an example of the fuel-injection control at the time of acceleration. 6 is a timing chart showing changes in load factor, intake manifold pressure (actual boost pressure), engine speed, high-pressure rail fuel pressure, engine output torque, and smoke, PM, and PN during acceleration (depressing the accelerator pedal).

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

  First, an internal combustion engine (hereinafter also referred to as an engine) to which the present invention is applied will be described.

-Engine-
1 and 2 are diagrams showing a schematic configuration of an engine to which the present invention is applied. FIG. 2 shows only the configuration of one cylinder of the engine. In FIG. 2, illustration of the turbocharger and the EGR device is omitted.

  The engine 1 of this example is a four-cylinder gasoline engine mounted on a vehicle, and a piston 1c that reciprocates in the vertical direction is provided in a cylinder block 1a constituting each cylinder. 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 (projections) 17a are provided on the outer peripheral surface 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) 301 for detecting a crank angle is disposed near the side of the signal rotor 17. The crank position sensor 301 is, for example, an electromagnetic pickup, and generates a pulsed 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 301.

  A water temperature sensor 303 for detecting the coolant temperature of the engine cooling water is disposed in the cylinder block 1a of the engine 1. 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) 500.

  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 engine such as the piston 1 c, crankshaft 15, connecting rod 16, etc. It is supplied to each part 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 304, a compressor impeller 102 of a turbocharger 100 described later, and intake air that has been heated by supercharging in the turbocharger 100 are forcibly cooled. The intercooler 8 and the throttle valve 5 for adjusting the intake air amount of the engine 1 are arranged. An intake air temperature sensor 307 and an intake manifold pressure sensor (supercharging pressure sensor) 308 are arranged in the intake passage 11 (intake manifold 11b).

  The air flow meter 304 detects the intake air amount (new air amount). The intake air temperature sensor 307 detects the temperature of the air (intake air temperature) after being cooled by the intercooler 8 and before being taken into the engine 1. The intake manifold pressure sensor 308 detects the pressure in the intake manifold 11b, that is, the supercharging pressure (intake pressure).

  The throttle opening of the throttle valve 5 is driven and controlled by the ECU 500. 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 301 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 305, 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 302 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 302 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 302 becomes 1 each time the crankshaft 15 rotates twice (720 ° rotation). Two pulse signals are generated.

  From the output signals of the cam position sensor 302 and the crank position sensor 301, the piston position (intake stroke, compression stroke, explosion) of each cylinder (first cylinder # 1 to fourth cylinder # 4) during engine operation. (Stroke / 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, the three-way catalyst 9 is disposed in the exhaust passage 12 downstream of the turbine wheel 101 of the turbocharger 100 (downstream of the exhaust flow). 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 309 is disposed in the exhaust passage 12 upstream of the three-way catalyst 9 (upstream of the exhaust flow). The air-fuel ratio sensor 309 is a sensor that exhibits linear characteristics with respect to the air-fuel ratio. An O ₂ sensor 310 is disposed in the exhaust passage 12 on the downstream side of the three-way catalyst 9. The O ₂ sensor 310 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 theoretical air-fuel ratio, the O ₂ sensor 310 is determined to be rich, and conversely 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, 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, 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 401 and a high-pressure pump 402 as low-pressure pumps. The feed pump 401 pumps up the fuel (gasoline etc.) in the fuel tank 400 and supplies it to the low-pressure fuel delivery pipe 20 b and the high-pressure pump 402. The high pressure pump 402 pressurizes the low pressure fuel from the feed pump 401 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 500.

  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 500 for opening and closing (injection time / injection timing).

  An injection ratio (sharing ratio) between fuel injection (DI injection) by the in-cylinder injector 2a and 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.

-Turbocharger-
The engine 1 in this example is equipped with a turbocharger (supercharger) 100 that supercharges intake air using exhaust pressure.

  As shown in FIG. 1, the turbocharger 100 includes a turbine wheel 101 disposed in the exhaust passage 12, a compressor impeller 102 disposed in the intake passage 11, and the turbine wheel 101 and the compressor impeller 102 coupled together in a rotating manner. The turbine shaft 101 disposed in the exhaust passage 12 is rotated by the energy of the exhaust, and the compressor impeller 102 disposed in the intake passage 11 is rotated accordingly. Then, the intake air is supercharged by the rotation of the compressor impeller 102, and the supercharged air is forcibly sent into the combustion chamber 1 d of each cylinder of the engine 1.

  The turbine wheel 101 is accommodated in the turbine housing 110, and the compressor impeller 102 is accommodated in the compressor housing 120. The turbine housing 110 and the compressor housing 120 are attached to both sides of the center housing 130. The compressor impeller 102 and the compressor housing 120 constitute a compressor 100B, and the turbine wheel 101 and the turbine housing 110 constitute a turbine 100A.

  Further, in the turbocharger 100 of this example, an exhaust bypass passage 104 that communicates the upstream side and the downstream side of the turbine wheel 101 (bypasses the turbine wheel 101), and a wastegate valve that opens and closes the exhaust bypass passage 104 ( (WGV) 105 is provided, and the supercharging pressure can be controlled by adjusting the opening of the waste gate valve 105 and adjusting the amount of exhaust gas that bypasses the turbine wheel 101. The opening degree of the wastegate valve 105 is adjusted by the ECU 500.

  As the turbocharger 100, a variable nozzle type turbocharger (VNT) in which a variable nozzle vane mechanism is provided on the turbine 100A side may be used.

-EGR device-
The engine 1 is equipped with an EGR device (Exhaust Gas Recirculation device) 200. The EGR device 200 is a device that reduces the amount of NOx generated by lowering the combustion temperature in the combustion chamber 1d by introducing part of the exhaust gas into the intake air.

  As shown in FIG. 1, the EGR device 200 includes an exhaust passage 12 (exhaust manifold 12b) upstream of the turbine wheel 101 of the turbocharger 100 (upstream of the exhaust gas flow) and an intercooler 8 (compressor of the turbocharger 100). An EGR passage (exhaust gas recirculation passage) 201 communicating with the intake passage 11 (intake manifold 11b) on the downstream side (downstream of the intake air flow) of the impeller 102), an EGR cooler 202 provided in the EGR passage 201, and The EGR valve 203 is used.

  In the EGR device 200 having such a configuration, the EGR rate [EGR amount / (EGR amount + intake air amount (new air amount)) (%)] can be changed by adjusting the opening degree of the EGR valve 203. Thus, the EGR amount (exhaust gas recirculation amount) introduced from the exhaust passage 12 to the intake passage 11 can be adjusted.

  The EGR device 200 may be provided with an EGR bypass passage that bypasses the EGR cooler 202 and an EGR bypass switching valve.

-ECU-
As shown in FIG. 3, the ECU 500 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, a backup RAM 504, and the like.

  The ROM 502 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 501 executes various arithmetic processes based on various control programs and maps stored in the ROM 502. The RAM 503 is a memory that temporarily stores the calculation results of the CPU 501, data input from each sensor, and the like. The backup RAM 504 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory.

  The CPU 501, ROM 502, RAM 503, and backup RAM 504 are connected to each other via a bus 507 and to an input interface 505 and an output interface 506.

The input interface 505 includes a crank position sensor (engine speed sensor) 301, a cam position sensor 302, a water temperature sensor 303, an air flow meter 304, a throttle opening sensor 305, and an accelerator that outputs detection signals corresponding to the depression amount of the accelerator pedal. The pressure sensor 306, the intake air temperature sensor 307, the intake manifold pressure sensor (supercharging pressure sensor) 308, the air-fuel ratio sensor 309, the O ₂ sensor 310, and the pressure (fuel pressure) of the high-pressure fuel supplied to the in-cylinder injector 2a are detected. Various sensors such as a high pressure fuel pressure sensor 311 and a low pressure fuel pressure sensor 312 for detecting the pressure (fuel pressure) of low pressure fuel supplied to the port injector 2b are connected. Further, an ignition switch 313 is connected to the input interface 505. When the ignition switch 313 is turned on, cranking of the engine 1 by a starter motor (not shown) is started.

  The output interface 506 is connected to the in-cylinder injector 2a, the port injector 2b, the igniter 4 of the spark plug 3, the throttle motor 6 of the throttle valve 5, and the like.

  The ECU 500 controls the fuel injection amount (steady fuel injection control), the ignition timing control of the spark plug 3, and the drive 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 intake air amount control) are executed. Further, the ECU 500 executes the following “fuel injection control during acceleration”.

  The control apparatus for the supercharged internal combustion engine (engine) according to the present invention is realized by the program executed by the ECU 500 described above.

-Fuel injection amount control (steady state)-
First, the ROM 503 of the ECU 500 stores the injection ratio map shown in FIG.

  In the injection ratio map of FIG. 4, the fuel injection mode is tested in consideration of fuel consumption (fuel consumption rate) characteristics and output characteristics using the engine speed NE and the load ratio KL indicating the operating state of the engine 1 as parameters. A map adapted by simulation or the like, and a port injection region (PFi region) in which fuel is injected only by the port injector 2b, a shared region in which fuel is injected by the port injector 2b and the in-cylinder injector 2a (Direct injection and port injection region (PFi + DI)) and direct injection region (DI region) in which fuel is injected only by the in-cylinder injector 2a are set.

  In addition, in addition to the engine operating state parameters such as the engine speed NE and the load factor KL, a map in which the injection ratio is set in consideration of the EGR amount may be used as the injection ratio map.

  The ECU 500 refers to the map of FIG. 4 based on the engine speed NE obtained from the output signal of the crank position sensor 301 and the engine load factor KL (from the in-cylinder injector 2a). The fuel sharing ratio: Di ratio) R (%) is obtained, and the fuel injection is executed by calculating the injection time and the injection timing based on the injection ratio R and the required injection amount.

  Specifically, when the engine operating state (engine speed / load factor) is in the PFi region (injection ratio R = 0%), it is obtained from the PFi required injection amount and the output signal of the fuel pressure sensor 312 for low-pressure fuel. Based on the fuel pressure and the capacity (flow rate size) of the port injector 2b, the PFi injection time and the PFi injection timing of the low pressure fuel injected from the port injector 2b are calculated, and the calculated PFi injection time and PFi are calculated. Based on the injection timing, the port injection injector 2b is controlled to open and close to perform fuel injection.

  When the engine operating state (engine speed / load factor) is in the DI region (split ratio R = 100%), the Di required injection amount, the fuel pressure obtained from the output signal of the fuel pressure sensor 311 for high pressure fuel, and the cylinder Based on the capacity (flow rate size) of the injecting 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 based on the calculated DI injection time and DI injection timing. The in-cylinder injector 2a is controlled to open and close to perform fuel injection.

  When the engine operating state (engine speed / load factor) is in a shared region (0% <split distribution ratio R <100%), the DI required injection amount (injection amount for cylinder injection 2a) based on the spray split ratio R ( The total required injection amount × the injection ratio R / 100) and the PFi required injection amount of the port injector 2b (the total required injection amount × (1−the injection ratio R / 100)) are obtained, and the same as described above. , DI injection time and DI injection timing, and 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. For example, the engine injection 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 the engine speed NE, the intake air amount obtained from the output signal of the air flow meter 304, the throttle opening obtained from the output signal of the throttle opening sensor 305, and the like. Can be calculated.

-Fuel injection control during acceleration-
Next, fuel injection control performed by the ECU 500 during acceleration (when the engine 1 is accelerated) will be described with reference to the flowchart of FIG. The control routine of FIG. 5 is repeatedly executed by the ECU 500 every predetermined time (for example, every several msec).

  First, in step ST101, it is determined whether or not it is during acceleration (during engine acceleration). Specifically, for example, it is determined whether or not the amount of change per unit time of the accelerator opening (the amount of depression of the accelerator pedal) obtained from the output signal of the accelerator opening sensor 306 is equal to or greater than a predetermined acceleration determination threshold value. To do. If the determination result is negative (NO) (accelerator opening change amount <acceleration determination threshold), the process returns. If the determination result in step ST101 is affirmative (YES) ([accelerator opening change amount ≧ acceleration determination threshold] and it is determined “acceleration”), the process proceeds to step ST102.

  Here, the acceleration determination threshold used for the determination in step ST101 is set to a value adapted by experiment / calculation in consideration of the target engine model. Specifically, for example, the acceleration determination threshold is set to 20% / sec to 30% / sec, and it is determined whether or not it is “acceleration”. In addition, this acceleration determination threshold value is not limited to this, You may employ | adopt another numerical value.

  The determination process at the time of “acceleration” in step ST101 may be performed based on other engine operating conditions such as the throttle opening obtained from the output signal of the throttle opening sensor 305. You may make it determine "at the time of acceleration" by another well-known method.

  In step ST102, only fuel injection (PFi injection) from the port injector 2b is executed regardless of the operating state of the engine 1. The fuel injection only by the port injector 2b starts when acceleration is requested (when the accelerator pedal is depressed: for example, at the time t1 in FIG. 6).

  Next, in step ST103, a required supercharging pressure at the time of acceleration is calculated. Specifically, for example, based on a required load that is one of the engine operating states (determined according to the accelerator pedal operation amount during acceleration (accelerator opening detected by the accelerator opening sensor 306)), The target boost pressure is calculated and set with reference to a known map or the like. The required load is smaller as the accelerator opening is smaller and larger as the accelerator opening is larger. Further, the target supercharging pressure becomes a larger value as the required load is larger.

  In step ST104, the current actual boost pressure is read from the output signal of the intake manifold pressure sensor 308, and has the actual boost pressure reached the target boost pressure (target boost pressure during acceleration) calculated in step ST103? Determine whether or not. When the determination result is negative (NO) (when the current actual boost pressure is smaller than the target boost pressure), fuel injection by only the port injector 2b is continued. The determination process in step ST104 is repeatedly executed at predetermined time intervals (for example, every several msec).

  And when the determination result of step ST104 is affirmative (YES), that is, when the current actual boost pressure has increased to the target boost pressure (when the boost pressure has risen sufficiently), Returning to the regular fuel injection control, the fuel injection control using the injection ratio map of FIG. 4 is executed (step ST105).

  Next, a specific example of the control of this example will be described with reference to the timing chart of FIG.

  First, for example, when the accelerator pedal is depressed at the time t1 in FIG. 6 from the idling state (when there is an acceleration request), the required load (load factor) increases stepwise (for example, the load factor is 100%). To the vicinity). At this time, on the injection ratio map (for steady state) shown in FIG. 4, the engine operating condition shifts from Pa to Pb and enters the DI region. In the conventional control, the injection by only the in-cylinder injector 2a ( DI injection) is executed. In such a situation (a situation where only DI injection is executed during acceleration), smoke may be generated and exhaust emission may deteriorate. In other words, since the injection by only the in-cylinder injector 2a has a low homogeneity of the air-fuel mixture, smoke may occur if a supercharging delay occurs due to the turbo lag during acceleration.

  In order to eliminate such a problem, in the control of this example, the supercharging delay due to the turbo lag at the time of acceleration described above is taken into consideration, as shown in FIG. Until the pressure rises (from t1 to t2 (until the boost pressure rises sufficiently)), only fuel injection (PFi injection) from the port injector 2b is performed. Such fuel injection increases the homogeneity of the air-fuel mixture and increases the efficiency of air utilization, so that it is possible to suppress the occurrence of smoke during acceleration (the conventional control is a broken line). As a result, exhaust emission can be improved. Further, since the combustion state becomes stable when the homogeneity of the air-fuel mixture becomes high, it is possible to increase the engine output torque as shown in FIG. 6 (the conventional control is a broken line), and the drivability can be improved. it can.

  The control (fuel injection control at the time of acceleration) in this example is not limited to the acceleration from the idling operation state (when the accelerator pedal is depressed), for example, a state in which a constant speed operation is performed on a highway (steady operation) In the case of acceleration from other steady operation states, such as when the acceleration state is entered by depressing the accelerator pedal (when entering the direct injection region (DI region) shown in FIG. 6) from the state) In addition, only the fuel injection from the port injector 2b may be performed until the actual boost pressure rises to the target boost pressure.

-Other embodiments-
In the above example, the case where the present invention is applied to a four-cylinder gasoline engine has been described. 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.

  Further, the present invention is not limited to a gasoline engine, and can be applied to control of a flex-fuel internal combustion engine that can use, for example, an alcohol-containing fuel in which gasoline and alcohol are mixed at an arbitrary ratio.

  The present invention can be used for control of an internal combustion engine, and more specifically, is effectively used for fuel injection control during acceleration in an internal combustion engine including a supercharger that supercharges air sucked into a combustion chamber. be able to.

1 Engine 1d Combustion chamber 2a In-cylinder injector (in-cylinder fuel injection valve)
2b Injector for port injection (fuel injection valve for intake passage)
DESCRIPTION OF SYMBOLS 11 Intake passage 12 Exhaust passage 12b Exhaust manifold 100 Turbocharger 101 Turbine wheel 102 Compressor impeller 301 Crank position sensor (engine speed sensor)
305 throttle opening sensor 306 accelerator opening sensor 308 intake manifold pressure sensor (supercharging pressure sensor)
309 Air-fuel ratio sensor 500 ECU

Claims (3)

An in-cylinder fuel injection valve that directly injects fuel into the combustion chamber, an intake passage fuel injection valve that injects fuel into the intake passage, and a supercharger that supercharges the air sucked into the combustion chamber. A control device for an internal combustion engine with a supercharger,
Fuel injection control means for performing only fuel injection from the fuel injection valve for the intake passage until the supercharging pressure by the supercharger rises to a target supercharging pressure during acceleration is provided. Control device for an internal combustion engine with a supercharger. The control device for an internal combustion engine with a supercharger according to claim 1,
Actual supercharging pressure recognition means for recognizing the actual supercharging pressure of the intake air supercharged by the supercharger, and target supercharging pressure setting means for setting a target supercharging pressure based on the operating state of the internal combustion engine; With
The fuel injection control means until the actual boost pressure recognized by the actual boost pressure recognition means during acceleration rises to the target boost pressure set by the target boost pressure setting means. A control apparatus for an internal combustion engine with a supercharger, wherein only fuel injection from the fuel injection valve for intake passage is executed. The control apparatus for an internal combustion engine with a supercharger according to claim 2,
The actual supercharging pressure recognition means is a supercharging pressure sensor disposed in an intake passage on the downstream side of the supercharger, and is configured to recognize the actual supercharging pressure from the output of the supercharging pressure sensor. A control device for an internal combustion engine with a supercharger.

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