JP2009235920A - Fuel injection control device of cylinder injection internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the acceleration response of a cylinder injection internal combustion engine with a supercharger. <P>SOLUTION: After securing the amount of oxygen required for recombustion through the increase in the amount of oxygen in an exhaust pipe 22 by forcing sucked air to blow by during valve overlap in the vicinity of the intake top dead center, main injection is executed from an intake stroke to the early stage of a compression stroke (for instance, BTDC300°CA-BTDC160°CA) after the valve overlap, and then additional injection is executed from an intermediate stage to the latter stage of the compression stroke (for instance, BTDC100°CA-BTDC0°CA). By so doing, a combustible gas component containing unburned HC is discharged in the exhaust pipe 22 while increasing exhaust temperature by burning a part of fuel injected into a cylinder by the additional injection. As a result, rotation speed of an exhaust turbine 26 can be increased by increasing energy of exhaust gas through the reliable recombustion of combustible gas component in the exhaust pipe 22 to increase boost pressure of a supercharger 25, thereby enhancing the acceleration response. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for a direct injection internal combustion engine equipped with an exhaust turbine supercharger.

  In recent years, in an internal combustion engine (engine) mounted on a vehicle, an exhaust turbine supercharger (so-called turbocharger) is mounted on a direct injection internal combustion engine in order to achieve both fuel saving and high output. There is. In this system, an exhaust turbine provided in an exhaust passage of an internal combustion engine is connected to a compressor provided in an intake passage, and the exhaust turbine is rotationally driven by exhaust gas energy to rotationally drive the compressor to supercharge intake air. Like to do.

In such a cylinder injection internal combustion engine with a supercharger, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2000-345889), acceleration response in a low rotation / low load region is improved. Therefore, after the main injection is executed in the compression stroke in the low rotation / low load range, the additional combustion is executed at a time when the combustion can be recombusted in the expansion stroke, so that the combustible gas components are reburned in the exhaust passage. There is one that increases the supercharging pressure by increasing the rotational speed of the exhaust turbine by increasing the energy of the exhaust gas.
Japanese Patent Laid-Open No. 10-322099 (pages 4 to 5 etc.)

  The technique disclosed in Patent Document 1 performs additional injection in an expansion stroke in a low rotation / low load region to re-combust combustible gas components in the exhaust passage to increase the supercharging pressure. When the technique of Patent Document 1 is applied to a high load region, the amount of oxygen in the exhaust gas is insufficient compared to the amount of oxygen necessary for recombustion, and it becomes difficult to cause recombustion sufficiently. The reason for this is that since the engine is operated at a lean air-fuel ratio in the low load region, the oxygen concentration in the exhaust gas is high and the amount of oxygen necessary for recombustion can be secured, but in the high load region, the output torque is increased. This is because the oxygen concentration in the exhaust gas becomes low because the air-fuel ratio is operated near the stoichiometric ratio.

  Further, in the technique of Patent Document 1, since additional injection is executed in the expansion stroke, the heat energy of the exhaust gas is deprived by the vaporization heat of the fuel of the additional injection, and the exhaust temperature is lowered accordingly, and the exhaust temperature It is difficult to raise the temperature to the high temperature range necessary for recombustion, which also makes it difficult to cause recombustion.

  As a countermeasure, it is conceivable to retard the ignition timing and raise the exhaust gas temperature. However, if the ignition timing is retarded, there is a drawback that the output decreases and the acceleration response is impaired.

  The present invention has been made in view of such circumstances. Therefore, the object of the present invention is to ensure that the combustible gas components are reburned in the exhaust passage so as to drive the exhaust turbine of the supercharger. It is an object of the present invention to provide a fuel injection control device for a cylinder injection internal combustion engine with a supercharger capable of increasing the supercharging pressure of the supercharger and improving the acceleration response.

  In order to achieve the above object, an invention according to claim 1 is directed to a fuel injection valve that directly injects fuel into a cylinder, and a supercharger that supercharges intake air by rotating an exhaust turbine with the energy of exhaust gas. And a fuel injection control device for a cylinder injection internal combustion engine with a supercharger comprising a fuel injection control means for controlling a fuel injection operation of the fuel injection valve, wherein the fuel injection control means The first fuel injection (main injection) for causing the main combustion is performed from the intake stroke after the valve overlap near the intake top dead center to the initial stage of the compression stroke, and then the combustible gas component is introduced into the exhaust passage. The second fuel injection (additional injection) for discharging and reburning in the exhaust passage is executed from the middle stage to the latter stage of the compression stroke.

  In this configuration, during the valve overlap near the intake top dead center (period when both the intake valve and the exhaust valve are open), the intake air is blown through to increase the amount of oxygen in the exhaust passage, which is necessary for recombustion. After securing the amount of oxygen, the first fuel injection for causing the main combustion of the air-fuel mixture in the cylinder is performed from the intake stroke to the beginning of the compression stroke, and then the second fuel injection is started from the middle of the compression stroke. By executing in the latter period, a part of the fuel injected into the cylinder in the second fuel injection is burned to raise the exhaust temperature, and the combustible gas component including unburned HC can be discharged into the exhaust passage. it can. As a result, the amount of combustible gas necessary for recombustion is discharged into the exhaust passage while ensuring the amount of oxygen necessary for recombustion in the exhaust passage and raising the exhaust temperature to a high temperature range necessary for recombustion. Therefore, the combustible gas component can be reliably reburned in the exhaust passage to increase the energy of the exhaust gas, thereby increasing the rotation speed of the exhaust turbine and increasing the supercharging pressure of the supercharger. Acceleration response can be improved.

  In this case, as in claim 2, the operating region in which the second fuel injection is executed is limited to a region that is not less than a predetermined load and not more than a predetermined engine speed, and switching between execution and stop of the second fuel injection. It is advisable to have hysteresis in the. Here, the reason why the operation region in which the second fuel injection is performed is set to be equal to or greater than the predetermined load is that the second fuel injection is performed in a high load region that is operated at an air-fuel ratio in the vicinity of the stoichiometry. The reason why the operating region in which the fuel injection is performed is set to be equal to or lower than the predetermined engine rotation speed is that the exhaust pressure increases as the engine rotation speed increases. Therefore, if the engine rotation speed increases, the exhaust pressure becomes higher than the intake pressure. This is because the intake air does not blow through during the valve overlap. If the engine speed decreases, the exhaust pressure becomes lower than the intake pressure, and intake air can be blown out during the valve overlap. Further, if hysteresis is provided for switching between execution and stop of the second fuel injection, execution and stop of the second fuel injection are frequently switched near the boundary of the operation region in which the second fuel injection is performed. Hunting phenomenon can be prevented.

  Further, as in claim 3, the exhaust gas purifying catalyst provided on the downstream side of the exhaust turbine in the exhaust passage, and either the upstream side or the downstream side of the catalyst or the upstream side of the exhaust turbine. Exhaust temperature determination means for detecting or estimating the exhaust temperature at the position, and prohibiting the second fuel injection (reburning) when the exhaust temperature detected or estimated by the exhaust temperature determination means exceeds a predetermined temperature It is good to do. In this way, in the high temperature region where exhaust system parts such as the catalyst and air-fuel ratio sensor installed in the exhaust passage may be damaged by exhaust heat, the second fuel injection (reburning) is prohibited and the exhaust temperature is prohibited. And the exhaust system parts can be prevented from being damaged by the exhaust heat.

  Further, as a method of setting the injection amount of the first fuel injection and the injection amount of the second fuel injection, for example, as in claim 4, the injection amount of the first fuel injection is caused to cause main combustion. The optimal injection amount is set, and the injection amount of the second fuel injection is set to a minimum injection amount necessary to cause re-combustion in the exhaust passage, or as in claim 5 The injection amount of the first fuel injection is set by multiplying the injection amount of the first fuel injection by a coefficient according to the operating condition of the internal combustion engine, or the first fuel injection and The total injection amount with the second fuel injection is set according to the operating condition of the internal combustion engine, and the total injection amount is set at a ratio according to the operating condition of the internal combustion engine with the second fuel injection amount and the second fuel injection amount. You may make it distribute to the injection quantity of fuel injection. In any method, it is possible to set the injection amount of the second fuel injection to an injection amount necessary for causing recombustion in the exhaust passage while suppressing deterioration of fuel consumption.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A downstream side of the air flow meter 14 is provided with a compressor 27 of an exhaust turbine supercharger 25 described later and an intercooler 31 that cools intake air pressurized by the compressor 27. On the downstream side of the intercooler 31, a throttle valve 15 whose opening is adjusted by a motor or the like and a throttle opening sensor 16 for detecting the throttle opening are provided.

  Further, a surge tank 17 is provided on the downstream side of the throttle valve 15, and an intake pressure sensor 18 that detects a downstream pressure (intake pressure) of the throttle valve 15 is provided in the surge tank 17. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for directly injecting fuel into the cylinder is attached to the upper part of each cylinder. .

  A spark plug 21 is attached to the cylinder head of the engine 11 for each cylinder, and an air-fuel mixture in each cylinder is ignited by spark discharge of each spark plug 21. Further, the engine 11 is equipped with variable valve timing devices (VVT) 43 and 44 that change the opening / closing timing (valve timing) of the intake valve 41 and the exhaust valve 42 according to the engine operating state. Only the intake-side variable valve timing device 43 may be provided, and the exhaust-side variable valve timing device 44 may be omitted.

  On the other hand, the exhaust pipe 22 (exhaust passage) of the engine 11 is provided with an air-fuel ratio sensor 24 (or oxygen sensor) that detects the air-fuel ratio (or rich / lean) of the exhaust gas. A catalyst 23 such as a three-way catalyst for purifying exhaust gas is provided (on the downstream side of the exhaust turbine 26 in this embodiment).

  An exhaust turbine supercharger 25 is mounted on the engine 11. In the supercharger 25, an exhaust turbine 26 is provided in the exhaust pipe 22, an air-fuel ratio sensor 24 is disposed between the exhaust turbine 26 and the catalyst 23 on the downstream side thereof, and the air flow meter 14 in the intake pipe 12. And the throttle valve 15 is provided with a compressor 27. In the supercharger 25, an exhaust turbine 26 and a compressor 27 are connected, and the exhaust turbine 26 is rotationally driven by the energy of exhaust gas, whereby the compressor 27 is rotationally driven to supercharge intake air.

  A cooling water temperature sensor 36 that detects the cooling water temperature and a crank angle sensor 37 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 37, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 38. The ECU 38 is mainly composed of a microcomputer, and causes the main combustion of the air-fuel mixture in the cylinder by executing the routines of FIGS. 2 to 4 stored in a built-in ROM (storage means). The first fuel injection (hereinafter referred to as “main injection”) is executed from the intake stroke after valve overlap near the intake top dead center to the initial stage of the compression stroke (for example, BTDC 300 ° C. A to BTDC 160 ° C. A), The second fuel injection (hereinafter referred to as “additional injection”) for discharging the combustible gas component into the exhaust pipe 22 and re-combusting in the exhaust pipe 22 is performed from the middle stage to the latter stage (for example, BTDC 100 ° C. A to BTDC0). At a temperature of 0 ° C.). Hereinafter, the processing content of each routine of FIGS. 2-4 is demonstrated.

[Fuel injection control routine]
The fuel injection control routine of FIG. 2 is executed immediately before the main injection timing of each cylinder is set, and serves as fuel injection control means in the claims. When this routine is started, first, at step 100, a main injection control routine of FIG. 3 to be described later is executed, and at step 200, an additional injection control routine of FIG. 4 to be described later is executed.

[Main injection control routine]
When the main injection control routine of FIG. 3 is started in step 100 of the fuel injection control routine of FIG. 2, first, in step 101, the optimum main injection amount for causing the main combustion of the air-fuel mixture in the cylinder is determined. It is calculated by a map or the like according to operating conditions, required torque, and the like.

Thereafter, the process proceeds to step 102, and main injection timing (timing for executing main injection) is calculated from a map or the like. In this case, the main injection timing is the current engine operating conditions (engine speed, load, etc.) in the range from the intake stroke after valve overlap near the intake top dead center to the initial stage of the compression stroke (for example, BTDC 300 ° C. A to BTDC 160 ° C. A). Etc.).
Thereafter, the process proceeds to step 103, and main injection is executed at the main injection timing calculated in step 102.

[Additional injection control routine]
When the additional injection control routine of FIG. 4 is started in step 200 of the fuel injection control routine of FIG. 2, first, in step 201, whether or not the cooling water temperature detected by the cooling water temperature sensor 36 is equal to or higher than a predetermined water temperature (that is, It is determined whether or not the engine 11 has been warmed up. If the temperature is lower than the predetermined water temperature, it is determined that the additional injection execution condition is not satisfied, and this routine is immediately terminated.

  On the other hand, if it is determined in step 201 that the cooling water temperature is equal to or higher than the predetermined water temperature (warming-up completion), the process proceeds to step 202, and the intake and exhaust variable valve timing devices (VVT) 43 and 44 are operable. If the intake / exhaust variable valve timing devices (VVT) 43 and 44 are not in an operable state, it is determined that the condition for executing the additional injection is not satisfied, and this routine is immediately terminated. .

  On the other hand, if it is determined in step 203 that the intake / exhaust variable valve timing devices (VVT) 43 and 44 are operable, the routine proceeds to step 203, where the current engine operation region is within the additional injection region. It is determined whether or not. At this time, the determination values Neth and Pmth that define the boundary line of the additional injection region are set by the engine speed Neth and the load Pmth (for example, intake pipe pressure, throttle opening, etc.) as shown in FIG. An area where the engine speed is equal to or greater than the value Pmth and equal to or less than the determination value Neth is an additional injection area.

  Here, the reason why the load region in which the additional injection is performed is set to the determination value Pmth or more is to perform the additional injection in a high load region that is operated at an air-fuel ratio in the vicinity of the stoichiometric, and an engine that performs the additional injection. The reason why the rotational speed region is set to the determination value Neth or less is that the exhaust pressure increases as the engine rotational speed increases. Therefore, if the engine rotational speed increases, the exhaust pressure becomes higher than the intake pressure and the valve overlaps ( This is because the intake air does not blow through during the period when both the intake valve 41 and the exhaust valve 42 are open. If the engine speed decreases, the exhaust pressure becomes lower than the intake pressure, and intake air can be blown out during the valve overlap.

  Further, in this embodiment, hysteresis is provided for switching between execution and stop of additional injection. Thereby, it is possible to prevent a hunting phenomenon in which the execution and stop of the additional injection are frequently switched near the boundary of the operation region in which the additional injection is executed. In this case, in order to further enhance the hunting prevention effect, the elapsed time after switching between execution and stop of additional injection is measured, and switching between execution and stop of additional injection is continued until this elapsed time exceeds a predetermined switching prohibition time. May be prohibited.

  If it is determined in step 203 that the current engine operation region is not within the additional injection region, this routine is terminated without performing the subsequent processing, but the current engine operation region is within the additional injection region. If YES, the routine proceeds to step 204, where the exhaust temperature at any position upstream or downstream of the catalyst 23 or upstream of the exhaust turbine 26 is within a predetermined temperature range (Tlow <exhaust temperature <Thigh). It is determined whether or not there is. Here, the lower limit temperature Tlow in the predetermined temperature range corresponds to the minimum exhaust temperature necessary for recombustion, and the upper limit temperature Thigh indicates that exhaust system parts such as the catalyst 23 and the air-fuel ratio sensor 24 are damaged by exhaust heat. This corresponds to the upper exhaust temperature that can be prevented.

  The lower limit temperature Tlow and the upper limit temperature Thigh in the predetermined temperature range may be set to a predetermined constant temperature, but may be set according to engine operating conditions such as the engine speed as shown in FIGS. Further, in order to prevent a hunting phenomenon in which execution and stop of additional injection are frequently switched around the lower limit temperature Tlow and the upper limit temperature Thigh in the predetermined temperature range, the lower limit temperature Tlow and the upper limit temperature Thigh in the predetermined temperature range have hysteresis. You may make it. Furthermore, in order to enhance the effect of preventing hunting, the elapsed time after switching between execution and stop of additional injection is measured, and switching between execution and stop of additional injection is prohibited until this elapsed time exceeds a predetermined switching prohibition time. You may make it do. This switching prohibition time may be a predetermined time set in advance, or may be set according to engine operating conditions such as engine rotation speed as shown in FIG.

  At this time, the exhaust temperature may be detected by an exhaust temperature sensor (not shown), or may be estimated based on engine operating conditions and the like. This function plays a role as exhaust temperature determination means in the claims.

  If it is determined in step 204 described above that the exhaust temperature is equal to or lower than the lower limit temperature Tlow (exhaust temperature ≤ Tlow) or higher than the upper limit temperature Thigh (exhaust temperature ≥ Thigh), the additional injection is prohibited, and this routine is directly executed. finish.

  On the other hand, if it is determined in step 204 that the exhaust temperature is within the predetermined temperature range (Tlow <exhaust temperature <Thigh), the process proceeds to step 205, and the additional injection amount is calculated by one of the following methods.

[Calculation method of additional injection amount (part 1)]
The additional injection amount is set to a minimum injection amount necessary to cause recombustion in the exhaust pipe 22. This additional injection amount may be a predetermined fixed amount or may be calculated by a map or the like according to the current engine operating conditions (engine speed, load, etc.).

[Method for calculating additional injection amount (part 2)]
The additional injection amount is calculated by multiplying the main injection amount by a coefficient (ratio) according to the current engine operating conditions (engine speed, load, etc.). This coefficient may be a constant value set in advance, or may be calculated from the map of FIG. 9 according to the current engine operating conditions (engine speed, load, etc.).

[Calculation method of additional injection amount (part 3)]
The total injection amount of main injection and additional injection is calculated by a map etc. according to the current engine operating conditions (engine speed, load, etc.), and the total injection amount is calculated based on the current engine operating conditions (engine speed, load, etc.) ) Are distributed to the main injection amount and the additional injection amount at a ratio according to.

  After calculating the additional injection amount, the routine proceeds to step 206, where the additional injection timing is calculated from the map of FIG. 10 in accordance with the current engine operating conditions (engine speed, load, etc.). In the map of FIG. 10, the additional injection timing is represented by BTDC (crank angle before compression top dead center), but may be represented by ATDC (crank angle after intake top dead center). Alternatively, the additional injection timing may be obtained by adding a predetermined value corresponding to the current engine operating conditions (engine speed, load, etc.) to the main injection timing. In short, the additional injection timing may be set in accordance with the current engine operating conditions in the range from the middle stage to the latter stage of the compression stroke (for example, BTDC 100 ° C. A to BTDC 0 ° C. A).

  After calculating the additional injection timing, the routine proceeds to step 207, where the ignition timing for additional injection is calculated from the map of FIG. 11 according to the current engine operating conditions (engine speed, load, etc.). At this time, the ignition timing for additional injection approaches the compression top dead center (BTDC 0 ° C. A) as the engine speed decreases. For example, at 1000 rpm or less, the ignition timing for additional injection becomes the compression top dead center (BTDC 0 ° C.). A). For example, in an area of 1500 rpm or more, the ignition timing for additional injection is set to approach the compression top dead center side as the load increases.

Thereafter, the process proceeds to step 208, and additional injection is executed at the additional injection timing set in step 206.
When the additional injection is executed, the valve overlap amount near the intake top dead center is adjusted by the intake and exhaust variable valve timing devices (VVT) 43 and 44 so that an appropriate amount of intake air is blown through.

  In the present embodiment described above, the intake air is blown through during the valve overlap near the intake top dead center to increase the amount of oxygen in the exhaust pipe 22 to ensure the amount of oxygen necessary for re-combustion. After the injection is executed from the intake stroke to the initial stage of the compression stroke (for example, BTDC 300 ° C. A to BTDC 160 ° C. A), the additional injection is performed from the middle to the later stage of the compression stroke (for example, BTDC 100 ° C. A to BTDC 0 ° C. A) Combustible gas components including unburned HC can be discharged into the exhaust pipe 22 while burning a part of the fuel injected into the cylinder by injection to raise the exhaust temperature. As a result, an amount of oxygen necessary for recombustion is ensured in the exhaust pipe 22 and the amount of combustible gas component necessary for recombustion is increased in the exhaust pipe 22 while raising the exhaust temperature to a high temperature range necessary for recombustion. Since the exhaust gas can be discharged, the combustible gas component can be surely reburned in the exhaust pipe 22 to increase the energy of the exhaust gas, and the rotational speed of the exhaust turbine 26 can be increased. The acceleration response can be enhanced by increasing the pressure.

  FIG. 12 is a time chart showing the effect of the additional injection of this embodiment in comparison with the case where the additional injection is not performed. Compared with the case without additional injection, the effect of the boost pressure being significantly increased and the torque being significantly increased by performing the additional injection of the present embodiment can be obtained. In addition, if additional injection is performed from the middle to the latter half of the compression stroke as in this embodiment, a part of the fuel of the additional injection burns in the cylinder, so that the main injection amount (main injection time) is added accordingly. This can be reduced as compared with the case of none, and the deterioration of fuel consumption can be minimized. In addition, when additional injection is performed from the middle stage to the latter stage of the compression stroke as in this embodiment, the exhaust temperature at the outlet of the exhaust valve 42 rises slightly compared to the case without additional injection, and further, combustible gas generated by the additional injection. Is reburned in the exhaust pipe 22, so that the exhaust temperature at the inlet of the exhaust turbine 26 is significantly increased, and the supercharging pressure and torque are significantly increased.

  In addition, in this embodiment, since the additional injection (reburning) is prohibited when the exhaust gas temperature is equal to or higher than the predetermined temperature, exhaust system parts such as the catalyst 23 and the air-fuel ratio sensor 24 installed in the exhaust pipe 22 are not used. In a high temperature region that can be damaged by exhaust heat, additional injection (reburning) can be prohibited to lower the exhaust temperature, and exhaust system parts can be prevented from being damaged by exhaust heat.

  In the present invention, the configuration of the supercharger 25 may be changed as appropriate. For example, an exhaust bypass passage that bypasses the upstream side and the downstream side of the exhaust turbine 26 is provided, A waste gate valve for opening and closing the exhaust bypass passage is provided, or an intake bypass passage for bypassing the upstream side and the downstream side of the compressor 27 is provided, and the intake bypass passage is opened and closed in the middle of the intake bypass passage. It is good also as a structure which provided the air bypass valve.

1 is a schematic configuration diagram of an entire engine control system showing an embodiment of the present invention. It is a flowchart which shows the flow of a process of a fuel-injection control routine. It is a flowchart which shows the flow of a process of the main injection control routine. It is a flowchart which shows the flow of a process of an additional injection control routine. It is a figure which shows an example of the map of the engine speed Neth which sets the boundary line of an additional injection area | region, and load Pmth. It is a figure which shows an example of the map which sets the minimum temperature Tlow of the exhaust gas temperature range which performs additional injection according to an engine speed. It is a figure which shows an example of the map which sets the upper limit temperature Thigh of the exhaust gas temperature range which performs additional injection according to an engine speed. It is a figure which shows an example of the map which sets the switching prohibition time after switching of execution and stop of additional injection according to an engine speed. It is a figure which shows an example of the map which sets the coefficient which is a ratio of the additional injection quantity with respect to the main injection quantity according to engine operating conditions (engine speed, load). It is a figure which shows an example of the map which sets an additional injection timing according to engine driving | running conditions (engine rotational speed, load). It is a figure which shows an example of the map which sets the ignition timing for additional injection according to engine operating conditions (engine speed, load). It is a time chart which shows the effect by additional injection compared with the case where there is no additional injection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter, 15 ... Throttle valve, 18 ... Intake pressure sensor, 20 ... Fuel injection valve, 21 ... Spark plug, 22 ... Exhaust pipe (exhaust passage), 24 ... Air-fuel ratio sensor, 25 ... supercharger, 26 ... exhaust turbine, 27 ... compressor, 38 ... ECU (fuel injection control means, exhaust temperature determination means)

Claims (6)

A fuel injection valve for directly injecting fuel into the cylinder, a supercharger for supercharging intake air by rotating an exhaust turbine with the energy of exhaust gas, and a fuel injection control means for controlling the fuel injection operation of the fuel injection valve In a fuel injection control device for a cylinder injection internal combustion engine with a supercharger comprising:
The fuel injection control means executes the first fuel injection for causing the main combustion of the air-fuel mixture in the cylinder from the intake stroke after the valve overlap near the intake top dead center to the initial stage of the compression stroke. In-cylinder injection internal combustion engine with a supercharger, characterized in that a second fuel injection for discharging a combustible gas component into the exhaust passage and re-combusting in the exhaust passage is executed from the middle to the later stage of the compression stroke Engine fuel injection control device.   The fuel injection control means limits an operation region in which the second fuel injection is performed to a region not less than a predetermined load and not more than a predetermined engine rotational speed, and is used for switching between execution and stop of the second fuel injection. 2. The fuel injection control device for a direct injection internal combustion engine with a supercharger according to claim 1, wherein hysteresis is provided. A catalyst for purifying exhaust gas provided downstream of the exhaust turbine in the exhaust passage;
Exhaust temperature determination means for detecting or estimating the exhaust temperature at any position upstream of the catalyst or downstream thereof or upstream of the exhaust turbine;
The fuel injection control means includes means for prohibiting the second fuel injection when the exhaust temperature detected or estimated by the exhaust temperature determination means is equal to or higher than a predetermined temperature. A fuel injection control device for a cylinder injection internal combustion engine with a supercharger.   The fuel injection control means sets the injection amount of the first fuel injection to an optimal injection amount for causing main combustion, and re-combusts the injection amount of the second fuel injection in the exhaust passage. 4. The fuel injection control device for a cylinder injection internal combustion engine with a supercharger according to claim 1, wherein the fuel injection control device is set to a minimum injection amount necessary for generating the same.   The fuel injection control means sets the injection amount of the first fuel injection to an optimal injection amount for causing main combustion, and the injection amount of the first fuel injection is in accordance with operating conditions of the internal combustion engine. 4. The fuel injection control device for a cylinder injection internal combustion engine with a supercharger according to any one of claims 1 to 3, wherein an injection amount of the second fuel injection is set by multiplying a coefficient.   The fuel injection control means sets a total injection amount of the first fuel injection and the second fuel injection according to an operating condition of the internal combustion engine, and sets the total injection amount according to the operating condition of the internal combustion engine. 4. A supercharger-equipped cylinder according to claim 1, further comprising means for distributing the injection amount of the first fuel injection and the injection amount of the second fuel injection at a predetermined ratio. A fuel injection control device for an injection type internal combustion engine.

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