JP2006037744A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately correct fuel adhered on a port wall surface even if change in DI ratio r (0<r<1) in an internal combustion engine equipped with an injector for cylinder injection and an injector for intake passage injection. <P>SOLUTION: An engine ECU300 executes a program including a step (S100) for calculating a correction factor fmw, a basic injection amount taupb of an injector 120 for intake passage injection, a basic injection amount taudb of an injector 110 for cylinder injection in wall surface adhesion and a step (S300) for substituting taudb+(taupb-taumin) for a final injection amount taud of the injector 110 for cylinder injection in case of taupb-taumin<0 (YES in S200) and substituting taumin+tauv for a final injection amount taup of the injector 120 for intake passage injection. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides first fuel injection means (in-cylinder injector) for injecting fuel into the cylinder and second fuel injection means (intake passage injection) for injecting fuel into the intake passage or intake port. In particular, when the share ratio between the first fuel injection means and the second fuel injection means is changed, the amount of fuel adhering to the inner wall surface of the intake port is reduced. It relates to correction technology.

  A first fuel injection valve for injecting fuel into the engine intake passage (in the background art, an intake passage injection injector) and a second fuel injection valve for injecting fuel constantly into the engine combustion chamber (background) In the technology, an in-cylinder injector) is provided, and when the engine load is lower than a predetermined set load, fuel injection from the first fuel injection valve (intake passage injection injector) is stopped and the engine load is stopped. An internal combustion engine is known in which fuel is injected from a first fuel injection valve (intake passage injector) when is higher than a set load. In this internal combustion engine, a total injection amount, which is the sum of fuels injected from both fuel injection valves, is predetermined as a function of the engine load, and this total injection amount is increased as the engine load increases.

  In such an internal combustion engine, when the engine load is higher than the set load and fuel injection from the first fuel injection valve (intake passage injection injector) is started, the first fuel injection valve (intake passage injection injector) is started. As a result, the amount of fuel supplied from the intake passage to the engine combustion chamber is equal to the amount of fuel injected from the first fuel injection valve (intake passage injector). Less. Accordingly, when fuel injection from each fuel injection valve is performed based on a predetermined injection amount as a function of the load of the internal combustion engine, fuel injection from the first fuel injection valve (intake passage injection injector) is started. As a result, the amount of fuel actually supplied into the engine combustion chamber becomes smaller than the required fuel amount (lean state), which causes a problem that the output torque of the engine is temporarily reduced.

  In such an internal combustion engine, when the engine load is lower than the set load and the fuel injection from the first fuel injection valve (intake passage injection injector) is stopped, the fuel adhering to the inner wall surface of the intake passage Continues to be supplied into the engine combustion chamber. As a result, when fuel injection from each fuel injection valve is performed based on a predetermined injection amount as a function of the load of the internal combustion engine, fuel injection from the first fuel injection valve (intake passage injection injector) is stopped. In addition, the amount of fuel actually supplied into the engine combustion chamber becomes larger than the required fuel amount (rich state), and therefore the engine output torque temporarily increases.

  Japanese Patent Application Laid-Open No. 5-231221 (Patent Document 1) includes an in-cylinder injector that injects fuel into a cylinder and an intake-path injector that injects fuel into an intake passage or an intake port. In addition, a fuel injection type internal combustion engine that prevents engine output torque from fluctuating at the start and stop of port injection is disclosed. This fuel injection type internal combustion engine includes a first fuel injection valve (intake passage injection injector) for injecting fuel into the engine intake passage and a second fuel injection valve for injecting fuel into the engine combustion chamber. (In-cylinder injector), and when the operating state of the engine is within a predetermined operating range, the fuel injection from the first fuel injection valve is stopped and the operating state of the engine is determined in advance. An internal combustion engine in which fuel is injected from the first fuel injection valve when it is out of the operating region, and attached fuel that adheres to the inner wall surface of the intake passage when fuel injection from the first fuel injection valve is started Means for estimating the amount and estimating the amount of adhering fuel flowing into the engine combustion chamber when fuel injection from the first fuel injection valve is stopped, and fuel injection from the first fuel injection valve is started Sometimes second burn The fuel injection amount from the injection valve is corrected to increase by the amount of attached fuel, and the fuel injection amount from the second fuel injection valve is decreased by the inflow amount when fuel injection from the first fuel injection valve is stopped. Means.

According to this fuel injection type internal combustion engine, when the fuel injection from the first fuel injection valve is started, the amount of fuel injected from the second fuel injection valve is corrected to increase by the amount of attached fuel, thereby actually entering the engine combustion chamber. The amount of fuel supplied becomes the required fuel amount, and when the fuel injection from the first fuel injection valve is stopped, the amount of fuel injected from the second fuel injection valve is corrected to decrease by the inflow amount, so that the engine combustion chamber actually The amount of fuel supplied to is the required fuel amount. As a result, the amount of fuel supplied into the engine combustion chamber becomes the required fuel amount at both the start and stop of the fuel supply from the first fuel injection valve. Can be blocked.
JP-A-5-2321221

  However, in the fuel injection internal combustion engine disclosed in Patent Document 1, when the fuel injection from the first fuel injection valve (intake passage injection injector) is not started, or the first fuel The fuel injection amount of the second fuel injection valve (in-cylinder injector) is corrected only when the fuel injection from the injection valve (intake passage injector) is stopped. Only. That is, when the DI ratio r (the ratio of the fuel injection amount of the in-cylinder injector to the total fuel injection amount) changes from 1 (the state in which only fuel injection from the in-cylinder injector is performed) (intake passage injection) The fuel injection from the in-cylinder injector) or when the DI ratio r changes from 0 (only the fuel injection from the intake manifold injector is performed). The state in which the injection is started) is a target, and the correction of the wall surface adhesion amount accompanying ON / OFF of the intake passage injector is merely performed by the in-cylinder injector. The DI ratio r changes from the first state of r (1) (0 <r (1) <1) to the second state of r (2) (0 <r (1) <r (2) <1). If the DI ratio has changed (DI ratio has increased) or the DI ratio r has changed from the third state of r (3) (0 <r (3) <1) to r (4) (0 <r (4) <r (3) The correction of the wall surface adhesion amount in the case of changing to the fourth state of <1) (DI ratio is reduced) is not targeted.

  The present invention has been made to solve the above-described problems, and has as its object the first fuel injection means for injecting fuel into the cylinder and the second fuel injection means for injecting fuel into the intake passage. And providing a control device for an internal combustion engine that can appropriately correct the wall surface adhering amount when the DI ratio changes.

  A control device according to a first aspect of the invention controls an internal combustion engine that includes a first fuel injection means for injecting fuel into a cylinder and a second fuel injection means for injecting fuel into an intake passage. To do. The control device is a control for controlling the fuel injection means so that the fuel is injected by the first fuel injection means and the second fuel injection means based on conditions required for the internal combustion engine. And means for estimating the fuel adhering to the wall surface of the intake passage when the injection amount sharing ratio changes. In the region where the fuel injection amount is shared between the first fuel injection unit and the second fuel injection unit, the control unit is configured to convert the wall-attached fuel between the first fuel injection unit and the second fuel injection unit. Means are included for controlling the fuel injection means to share and correct.

  According to the first invention, when the fuel is injected by the first fuel injection means (for example, in-cylinder injector) and the second fuel injection means (for example, intake manifold injector) When 0 <DI ratio r <1) and the DI ratio r increases stepwise (with the load on the internal combustion engine being the same) (r <1), the fuel injection amount of the intake manifold injector decreases stepwise. At this time, the fuel adhering to the intake port is sucked into the combustion chamber. Since the air-fuel ratio becomes rich as it is, the fuel adhering to the wall surface is corrected by the intake manifold injector. That is, correction is made so as to reduce the fuel injection amount of the intake manifold injector. When this correction causes a case where the fuel injection amount falls below the minimum injection amount of the intake manifold injector, it is no longer possible to correct the wall-attached fuel by reducing the fuel injection amount of the intake manifold injector. In this state, the air-fuel ratio is still rich, so that the fuel adhering to the wall surface is corrected using the in-cylinder injector. The fuel injection amount of the in-cylinder injector is subtracted by the amount of fuel injection that could not be corrected by the intake passage injector.

  Conversely, when the fuel is injected by the in-cylinder injector and the intake manifold injector (0 <DI ratio r <1), the DI ratio r is (with the same load on the internal combustion engine). When the pressure decreases stepwise (0 <r), the fuel injection amount of the intake manifold injector increases stepwise. At this time, the fuel sucked into the combustion chamber decreases until a predetermined amount of fuel adheres to the intake port. Since the air-fuel ratio becomes lean as it is, the fuel adhering to the wall surface is corrected by the intake manifold injector. That is, correction is performed so as to increase the fuel injection amount of the intake manifold injector. If this correction causes a case where the maximum injection amount of the intake manifold injector is exceeded, correction of wall-attached fuel by increasing the fuel injection amount of the intake manifold injector is no longer possible. In this state, since the air-fuel ratio is still lean, the in-cylinder injector is used to correct the wall-attached fuel. The amount of fuel injection that cannot be corrected by the intake manifold injector is added to obtain the fuel injection amount of the in-cylinder injector.

  In this way, the in-cylinder injector and the intake manifold injector share the fuel injection state and continue before and after the change of the DI ratio r. The ratio between the fuel injection amount from the injector and the fuel amount flowing in from the intake port is maintained at a desired value, and the fuel injection amount from the in-cylinder injector deviates from the DI ratio r. Accumulation of deposits at the nozzle and deterioration of combustion can be avoided. Further, it is possible to prevent the deterioration of the emission due to the delay in following the feedback of the air-fuel ratio. As a result, there is provided an internal combustion engine control device capable of appropriately correcting the wall surface adhering amount when the DI ratio changes in an internal combustion engine that shares injected fuel with an in-cylinder injector and an intake passage injector. can do.

  In the control device according to the second aspect of the invention, in addition to the configuration of the first aspect, the control means performs the second operation when the corrected fuel decrease amount is less than the minimum injection quantity of the second fuel injection means. Means for controlling the injector so that the amount of fuel injected from the fuel injection means is the minimum injection quantity and the remaining correction is performed with the fuel injection quantity from the first fuel injection means.

  According to the second invention, when the DI ratio r increases stepwise (r <1), the fuel injection amount of the intake manifold injector decreases stepwise. At this time, the fuel adhering to the intake port is sucked into the combustion chamber and the air-fuel ratio becomes rich. Therefore, the fuel adhering to the wall surface is corrected by the intake manifold injector. When the fuel injection amount of the intake passage injector is reduced so as to reduce the fuel injection amount of the intake passage injector, the fuel adhering to the wall surface by reducing the fuel injection amount of the intake passage injection injector no longer occurs. The correction of becomes impossible. In this state, the air-fuel ratio is still rich, so that the fuel adhering to the wall surface is corrected using the in-cylinder injector. The fuel injection amount of the in-cylinder injector can be subtracted by the amount of fuel injection that could not be corrected by the intake passage injector.

  In the control device according to the third aspect of the invention, in addition to the configuration of the first aspect, the control means may provide the second if the fuel increase amount by the correction exceeds the maximum injection quantity of the second fuel injection means. Means for controlling the injector so that the amount of fuel injected from the fuel injection means is the maximum injection quantity and the remaining correction is performed with the fuel injection quantity from the first fuel injection means.

  According to the third invention, when the DI ratio r decreases stepwise (0 <r), the fuel injection amount of the intake manifold injector increases stepwise. At this time, the amount of fuel sucked into the combustion chamber decreases until a predetermined amount of fuel adheres to the intake port, so the air-fuel ratio becomes lean. Therefore, the fuel adhering to the wall surface is corrected by the intake manifold injector. If there is a case where the maximum injection amount of the intake manifold injector is exceeded in order to increase the fuel injection amount of the intake manifold injector, the fuel adhering to the wall surface by increasing the fuel injection amount of the intake manifold injector The correction of becomes impossible. In this state, since the air-fuel ratio is still lean, the in-cylinder injector is used to correct the wall-attached fuel. The fuel injection amount of the in-cylinder injector can be added by adding the fuel injection amount that cannot be corrected by the intake manifold injector.

  In the control device according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the first fuel injection means is an in-cylinder injector, and the second fuel injection means is An intake passage injector.

  According to a fourth aspect of the present invention, in the internal combustion engine that separately provides the in-cylinder injector that is the first fuel injection means and the intake passage injection injector that is the second fuel injection means and shares the injected fuel, It is possible to provide a control device for an internal combustion engine that can appropriately correct the amount of wall surface adhesion when the ratio changes.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 shows a schematic configuration diagram of an engine system controlled by an engine ECU (Electronic Control Unit) which is a control device for an internal combustion engine according to an embodiment of the present invention. Although FIG. 1 shows an in-line four-cylinder gasoline engine as the engine, the present invention is not limited to such an engine.

  As shown in FIG. 1, the engine 10 includes four cylinders 112, and each cylinder 112 is connected to a common surge tank 30 via a corresponding intake manifold 20. The surge tank 30 is connected to an air cleaner 50 via an intake duct 40, an air flow meter 42 is disposed in the intake duct 40, and a throttle valve 70 driven by an electric motor 60 is disposed. The opening degree of throttle valve 70 is controlled based on the output signal of engine ECU 300 independently of accelerator pedal 100. On the other hand, each cylinder 112 is connected to a common exhaust manifold 80, and this exhaust manifold 80 is connected to a three-way catalytic converter 90.

  For each cylinder 112, an in-cylinder injector 110 for injecting fuel into the cylinder, and an intake passage injection injector 120 for injecting fuel into the intake port or / and the intake passage. And are provided respectively. These injectors 110 and 120 are controlled based on the output signal of engine ECU 300, respectively. The in-cylinder injectors 110 are connected to a common fuel distribution pipe 130, and this fuel distribution pipe 130 is connected to the fuel distribution pipe 130 through a check valve 140, and is driven by an engine. A high-pressure fuel pump 150 is connected. In the present embodiment, an internal combustion engine in which two injectors are separately provided will be described, but the present invention is not limited to such an internal combustion engine. For example, it may be an internal combustion engine having one injector that has both an in-cylinder injection function and an intake passage injection function.

  As shown in FIG. 1, the discharge side of the high-pressure fuel pump 150 is connected to the suction side of the high-pressure fuel pump 150 via an electromagnetic spill valve 152. When the amount of fuel supplied from the pump 150 into the fuel distribution pipe 130 is increased and the electromagnetic spill valve 152 is fully opened, the fuel supply from the high pressure fuel pump 150 to the fuel distribution pipe 130 is stopped. ing. Electromagnetic spill valve 152 is controlled based on the output signal of engine ECU 300.

  On the other hand, each intake passage injector 120 is connected to a common low-pressure fuel distribution pipe 160, and the fuel distribution pipe 160 and the high-pressure fuel pump 150 are connected to a common fuel pressure regulator 170 through an electric motor drive type. The low-pressure fuel pump 180 is connected. Further, the low pressure fuel pump 180 is connected to the fuel tank 200 via a fuel filter 190. The fuel pressure regulator 170 returns a part of the fuel discharged from the low-pressure fuel pump 180 to the fuel tank 200 when the fuel pressure of the fuel discharged from the low-pressure fuel pump 180 becomes higher than a predetermined set fuel pressure. Accordingly, the fuel pressure supplied to the intake manifold injector 120 and the fuel pressure supplied to the high-pressure fuel pump 150 are prevented from becoming higher than the set fuel pressure.

  The engine ECU 300 is composed of a digital computer, and is connected to each other via a bidirectional bus 310, a ROM (Read Only Memory) 320, a RAM (Random Access Memory) 330, a CPU (Central Processing Unit) 340, and an input port 350. And an output port 360.

  The air flow meter 42 generates an output voltage proportional to the amount of intake air, and the output voltage of the air flow meter 42 is input to the input port 350 via the A / D converter 370. A water temperature sensor 380 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine 10, and the output voltage of the water temperature sensor 380 is input to the input port 350 via the A / D converter 390.

  A fuel pressure sensor 400 that generates an output voltage proportional to the fuel pressure in the fuel distribution pipe 130 is attached to the fuel distribution pipe 130, and the output voltage of the fuel pressure sensor 400 is input via the A / D converter 410. Input to port 350. The exhaust manifold 80 upstream of the three-way catalytic converter 90 is provided with an air-fuel ratio sensor 420 that generates an output voltage proportional to the oxygen concentration in the exhaust gas. The output voltage of the air-fuel ratio sensor 420 is converted into an A / D converter. It is input to the input port 350 via 430.

The air-fuel ratio sensor 420 in the engine system according to the present embodiment is a global air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned by the engine 10. The air-fuel ratio sensor 420 may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture burned in the engine 10 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  The accelerator pedal 100 is connected to an accelerator opening sensor 440 that generates an output voltage proportional to the depression amount of the accelerator pedal 100, and the output voltage of the accelerator opening sensor 440 is input to the input port 350 via the A / D converter 450. Is input. The input port 350 is connected to a rotational speed sensor 460 that generates an output pulse representing the engine rotational speed. In the ROM 320 of the engine ECU 300, the value of the fuel injection amount and the engine cooling that are set according to the operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 440 and the engine speed sensor 460 described above are stored. Correction values based on the water temperature and the like are previously mapped and stored.

  Hereinafter, the fuel adhering to the intake port will be described.

  When the port injection amount Qp from the intake manifold injector 120 increases (DI ratio r decreases: 0 <r), when considering the fuel amount Qm adhering to the inner wall surface of the intake port, one port injection It is considered that the amount of fuel deposited by the amount Qp increases as the port injection amount Qp increases, and therefore the amount of fuel deposited by one port injection amount Qp is proportional to the port injection amount Qp. On the other hand, it is considered that the amount of attached fuel increases as the temperature of the inner wall surface of the intake port decreases. Therefore, the amount of attached fuel is inversely proportional to the temperature of the inner wall surface of the intake port. By the way, the temperature of the inner wall surface of the intake port is substantially proportional to the engine cooling water temperature Tw, so the amount of attached fuel is inversely proportional to the engine cooling water temperature Tw. In this way, the amount of fuel deposited by one port injection amount Qp is proportional to the port injection amount Qp and inversely proportional to the engine cooling water temperature Tw, so the amount of fuel deposited by one port injection amount Qp is Qp · f (Tw ). Therefore, when the port injection amount Qp is successively performed, the adhered fuel amount Qm is a cumulative value of Qp · f (Tw) (strictly speaking, however, the port injection amount Qp from the intake manifold injector 120 is The state of fuel adhering to the inner wall of the intake port before increasing must be considered).

  When the port injection amount Qp is initially increased, the adhered fuel amount Qm increases, but after a while, an equilibrium state is reached and the adhered fuel amount Qm becomes constant. The attached fuel amount Qm when the equilibrium state is reached, that is, the maximum value Qmax of the attached fuel amount Qm is a function of the absolute pressure PM in the intake port and the temperature of the inner wall surface of the intake port, that is, the engine coolant temperature Tw. That is, the lower the absolute value PM in the intake port is, the more the evaporation of the attached fuel is promoted. Therefore, the maximum value Qmax increases as the absolute pressure PM in the intake port increases. On the other hand, the maximum value Qmax increases as the engine coolant temperature Tw decreases.

  As described above, when the port injection amount Qp is increased, the amount of attached fuel gradually increases, and when the equilibrium state is reached, that is, when the maximum value Qmax is reached, the attached fuel starts to flow into the combustion chamber. Considering this, the amount of fuel that does not flow into the combustion chamber when the port injection amount Qp is increased is represented by the difference (Qmax−Qm) between the maximum value Qmax and the adhered fuel amount Qm. Accordingly, when the port injection amount Qp is increased, if the amount of correction (fmw) due to the wall surface adhesion is increased by (Qmax−Qm), the amount of fuel actually supplied into the combustion chamber matches the required total injection amount Qall. It will be.

  Conversely, when the fuel injection amount from the intake manifold injector 120 decreases (DI ratio r increases: r <1), the fuel adhering to the inner wall surface of the intake port gradually flows into the combustion chamber. . At this time, the inflow amount Qn of the adhering fuel flowing into the combustion chamber is considered to be proportional to the adhering fuel amount Qm. Further, since the inflow amount Qn is considered to increase as the intake amount Acc of the accelerator pedal 100 increases and the intake air amount increases, the inflow amount Qn is proportional to the depression amount Acc of the accelerator pedal 100. . Further, since the inflow amount Qn is considered to increase as the temperature of the inner wall surface of the intake port increases, the inflow amount Qn is considered to increase as the engine cooling water temperature Tw increases. Therefore, the inflow amount Qn is expressed by Qm · f (Acc) · f (Tw), and when the port injection amount Qp is decreased, Qm · f ( If the amount is reduced by (Acc) · f (Tw), the amount of fuel actually supplied to the combustion chamber matches the required total injection amount Qall (however, strictly speaking, the port from the intake manifold injector 120) Since the injection amount Qp is not stopped, it must be considered that the fuel adhering to the inner wall surface of the intake port in this state flows into the combustion chamber).

  With reference to FIG. 2, a control structure of a program executed by engine ECU 300 which is a control device according to the embodiment of the present invention will be described. This flowchart is executed at a predetermined time interval or at a predetermined crank angle of the engine 10.

In step (hereinafter, step is abbreviated as S) 100, engine ECU 300 calculates correction coefficient fmw due to wall adhesion, basic injection amount taupb of intake passage injector 120, and basic injection amount taudb of in-cylinder injector 110. calculate. At this time, the basic injection amount taudb of the in-cylinder injector 110 is
taudb = r × EQMAX × klfwd × fafd × kgd × kpr (1)
Is calculated by The basic injection amount taupb of the intake passage injector 120 is:
taupb = k × (1-r) × EQMAX × klfwd × fafp × kgp + fmw (2)
Is calculated as In the above equations (1) and (2), r is the injection ratio (DI ratio), EQMAX is the maximum injection amount, klfwd is the load factor, and fafd and fafp are in the stoichiometric state. It is a feedback coefficient, kgd is a learned value of the in-cylinder injector 110, kpr is a conversion coefficient corresponding to the fuel pressure, and kgp is a learned value of the intake manifold injector 120.

  In S200, engine ECU 300 determines whether or not a value obtained by subtracting minimum injection amount tanmin of intake manifold injector from basic injection amount taupb of intake manifold injector 120 is negative. If taupb-taumin <0 (YES in S200), the process proceeds to S300. If not (NO in S200), the process proceeds to S400.

  In S300, engine ECU 300 substitutes taudb + (taupb−taumin) for final injection amount taud of in-cylinder injector 110, and taumin + tauv (invalid injection amount) for final injection amount taup of intake manifold injector 120. Is assigned.

  In S400, engine ECU 300 substitutes taudb for the final injection amount taud of in-cylinder injector 110, and substitutes taupb for the final injection amount taup of intake manifold injector 120.

  The operation of engine 10 controlled by engine ECU 300, which is a control device for an internal combustion engine according to the present embodiment, based on the above-described structure and flowchart will be described with reference to the timing chart of FIG.

  As shown in FIG. 3A, when the DI ratio r is rapidly increased, the basic injection amount taupb from the intake manifold injector 120 is rapidly decreased as shown in FIG. As shown in (D), the basic injection amount taudb from the in-cylinder injector 110 increases rapidly. Further, as shown in FIG. 3B, the correction coefficient fmw due to wall adhesion gradually returns to 0 after suddenly becoming a negative value. The correction coefficient fmw due to the wall surface adhesion, the basic injection amount taupb of the intake manifold injector 120, and the basic injection amount taudb of the in-cylinder injector 110 are calculated at regular time intervals (S100).

  Since the fuel adhering to the intake port is sucked into the combustion chamber, the correction is first made by the intake passage injector 120. As shown in FIG. 3B, the correction coefficient fmw for wall surface adhesion is calculated as a negative value, and as shown in FIG. 3C, the basic injection amount taupb of the intake manifold injector 120 is calculated to be small. It is assumed that the basic injection amount taupb of intake passage injector 120 is lower than the minimum injection amount taumin of intake passage injector 120 (taupb−taumin <0) (YES in S200).

  When this happens, it becomes no longer possible to correct the fuel adhering to the wall surface by reducing the injected fuel amount Qp of the intake manifold injector 120. Therefore, the final injection amount taup on the intake passage injector 110 side is set to taumin + tauv (minimum fuel amount Qmin considering the ineffective portion) (S400). Even in this case, since the air-fuel ratio becomes rich, correction is performed using the in-cylinder injector 110. The final injection amount taud of the in-cylinder injector 110 is calculated by subtracting from the basic injection amount taudb of the in-cylinder injector 110 by the amount (taupb−taumin) that could not be corrected by the intake passage injector 120. To do.

  As described above, when the fuel is shared by the in-cylinder injector and the intake passage injector, the DI ratio r increases stepwise (r <1), and the intake passage injection The fuel injection amount of the injector for use decreases stepwise. At this time, the fuel adhering to the intake port is sucked into the combustion chamber and the air-fuel ratio becomes rich. Therefore, the fuel adhering to the wall surface is corrected by the intake manifold injector. When the fuel injection amount of the intake passage injector is reduced so as to reduce the fuel injection amount of the intake passage injector, the fuel adhering to the wall surface by reducing the fuel injection amount of the intake passage injection injector no longer occurs. The correction of becomes impossible. In this state, the air-fuel ratio is still rich, so that the fuel adhering to the wall surface is corrected using the in-cylinder injector. The fuel injection amount of the in-cylinder injector can be subtracted by the amount of fuel injection that could not be corrected by the intake passage injector.

  FIG. 4 shows a timing chart when the DI ratio r decreases stepwise (0 <r). 4A shows the DI ratio r, FIG. 4B shows the correction coefficient fmw due to wall adhesion, FIG. 4C shows the basic injection amount taupb and final injection amount taup of the intake manifold injector 120, and FIG. ) Shows the basic injection amount taudb and the final injection amount taud of the in-cylinder injector 110, respectively.

  The fuel is not sucked into the combustion chamber until the fuel adheres to the intake port and reaches an equilibrium state. Therefore, the correction is first made by the intake passage injection injector 120. As shown in FIG. 4B, the wall surface adhesion correction coefficient fmw is calculated as a positive value, and as shown in FIG. 4C, the basic injection amount taupb of the intake manifold injector 120 is calculated to be large. It is assumed that the basic injection amount taupb of the intake passage injector 120 exceeds the maximum injection amount taumax of the intake passage injector 120 (taupb−taumax> 0).

  When this happens, it becomes no longer possible to correct the fuel adhering to the wall surface by reducing the injected fuel amount Qp of the intake manifold injector 120. Therefore, the final injection amount taup on the intake passage injector 110 side is taumax. Even in this case, since the air-fuel ratio becomes lean, correction is performed using the in-cylinder injector 110. An amount equivalent to (taupb−taumax) that could not be corrected by intake manifold injector 120 (calculated in consideration of invalid injection) is added to basic injection amount taudb of in-cylinder injector 110. Thus, the final injection amount taud of the in-cylinder injector 110 is calculated.

  As described above, when the fuel is shared between the in-cylinder injector and the intake manifold injector, if the DI ratio r decreases stepwise (0 <r), the fuel of the intake manifold injector The injection amount increases stepwise. At this time, the amount of fuel sucked into the combustion chamber decreases until a predetermined amount of fuel adheres to the intake port, so the air-fuel ratio becomes lean. Therefore, the fuel adhering to the wall surface is corrected by the intake manifold injector. If there is a case where the maximum injection amount of the intake manifold injector is exceeded in order to increase the fuel injection amount of the intake manifold injector, the fuel adhering to the wall surface by increasing the fuel injection amount of the intake manifold injector The correction of becomes impossible. In this state, since the air-fuel ratio is still lean, the in-cylinder injector is used to correct the wall-attached fuel. The fuel injection amount of the in-cylinder injector can be added by adding the fuel injection amount that cannot be corrected by the intake manifold injector.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic configuration diagram of an engine system controlled by a control device according to an embodiment of the present invention. It is a flowchart which shows the control structure of the program performed by engine ECU which is a control apparatus which concerns on embodiment of this invention. It is a timing chart when DI ratio rises when controlled by engine ECU which is a control device concerning an embodiment of the invention. It is a timing chart when DI ratio falls, when it is controlled by engine ECU which is a control device concerning an embodiment of the invention.

Explanation of symbols

  10 engine, 20 intake manifold, 30 surge tank, 40 intake duct, 42 air flow meter, 50 air cleaner, 60 electric motor, 70 throttle valve, 80 exhaust manifold, 90 three-way catalytic converter, 100 accelerator pedal, 110 in-cylinder injector , 112 cylinder, 120 Injector injector, 130 Fuel distribution pipe, 140 Check valve, 150 High pressure fuel pump, 152 Electromagnetic spill valve, 160 Fuel distribution pipe (low pressure side), 170 Fuel pressure regulator, 180 Low pressure fuel pump, 190 fuel filter, 200 fuel tank, 300 engine ECU, 310 bidirectional bus, 320 ROM, 330 RAM, 340 CPU, 350 input port, 360 output port, 370, 39 , 410,430,450 A / D converter, 380 a water temperature sensor, 400 a fuel pressure sensor, 420 an air-fuel ratio sensor, 440 an accelerator opening sensor, 460 rpm sensor.

Claims (4)

A control device for an internal combustion engine comprising a first fuel injection means for injecting fuel into a cylinder and a second fuel injection means for injecting fuel into an intake passage,
Control means for controlling the fuel injection means so as to inject fuel in a shared manner between the first fuel injection means and the second fuel injection means based on conditions required for the internal combustion engine; ,
An estimation means for estimating the wall surface adhering fuel in the intake passage when the injection amount sharing ratio changes,
In the region where the fuel injection amount is shared by the first fuel injection unit and the second fuel injection unit, the control unit is configured to supply the wall-attached fuel to the first fuel injection unit and the second fuel injection unit. A control apparatus for an internal combustion engine, including means for controlling the fuel injection means so as to share and correct the fuel injection means.   When the fuel reduction amount by the correction is less than the minimum injection amount of the second fuel injection unit, the control unit sets the injected fuel amount from the second fuel injection unit as the minimum injection amount, and the remaining amount 2. The control apparatus for an internal combustion engine according to claim 1, further comprising means for controlling the fuel injection means so that the correction is performed with the fuel injection amount from the first fuel injection means.   When the fuel increase amount due to the correction exceeds the maximum injection amount of the second fuel injection unit, the control unit sets the injection fuel amount from the second fuel injection unit as the maximum injection amount, and the remaining amount 2. The control apparatus for an internal combustion engine according to claim 1, further comprising means for controlling the fuel injection means so that the correction is performed with the fuel injection amount from the first fuel injection means. The first fuel injection means is an in-cylinder injector,
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the second fuel injection means is an intake passage injector.

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