JP5071300B2 - Fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control device, and more specifically, fuel injection control including an intake path fuel injection valve that injects fuel into an intake path of an internal combustion engine and an in-cylinder fuel injection valve that injects fuel into a cylinder of the internal combustion engine. Relates to the device.

  Some fuel injection control apparatuses for internal combustion engines include two fuel injection valves, an intake path fuel injection valve that injects fuel into the intake path and an in-cylinder fuel injection valve that injects fuel into the cylinder. In such a fuel injection control device, a fuel injection amount of fuel is injected by at least one of the intake path fuel injection valve and the in-cylinder fuel injection valve and supplied to the internal combustion engine. Here, in the fuel injection control by the intake path fuel injection valve and the in-cylinder fuel injection valve at the start of the internal combustion engine, the start-time intake path for injecting fuel of the fuel injection amount set only by the intake path fuel injection valve An injection control and a start-time in-cylinder injection control in which a fuel injection amount set by only the in-cylinder fuel injection valve is injected once in a compression stroke are conceivable.

  By the way, in the fuel injection by the intake path fuel injection valve, the fuel injection amount is set so that the homogeneous air-fuel mixture in the cylinder becomes richer than the optimum point of emission when using normal fuel in consideration of variations in fuel properties. Therefore, the fuel injection amount increases more than the fuel injection amount corresponding to the optimum point of emission. In particular, when only starting intake path injection control is performed at the start of an internal combustion engine (immediately after starting or after a predetermined time has elapsed after starting), the deterioration of atomization / vaporization in heavy fuel or the intake path There is a problem that the fuel injection amount further increases in order to ensure the startability of the internal combustion engine because the fuel that contributes to combustion decreases due to the increase in fuel adhering, that is, the increase in port wetness.

  On the other hand, when fuel is injected by the in-cylinder fuel injection valve, particularly when a set amount of fuel injection is injected at a time in the compression stroke by the in-cylinder fuel injection valve, stratified combustion occurs, so the ignition plug A stratified mixture is formed in which the air-fuel mixture in the vicinity region is richer than the air-fuel mixture in the other regions in the cylinder, so that the air-fuel mixture in the vicinity of the spark plug does not become rich beyond the combustible range. Although the fuel injection amount is set so that the inside becomes lean, there is a problem that the emission is deteriorated and HC (hydrocarbon) emission increases here. In addition, when only the in-cylinder injection control is performed at the start of the internal combustion engine (after a predetermined time has elapsed after the start of the start), the fuel adhering to the surface of the piston increases, that is, the emission deteriorates due to an increase in piston wetness. Here, there is a problem that smoke (black smoke) emission increases.

  Conventionally, as shown in Patent Document 1, a fuel injection control device that performs start-up in-cylinder injection control until the first time or several times at the start of the internal combustion engine, and thereafter performs start-up intake path injection control. Has been proposed. The fuel injection control device disclosed in Patent Document 1 suppresses misfire and the like based on a decrease in fuel pressure when only the in-cylinder injection control at the start is performed at the start of the internal combustion engine, and the intake path injection control at the start at the start of the internal combustion engine. This suppresses the deterioration of startability when only the operation is performed.

JP 2005-113893 A

  However, in the fuel injection control device shown in Patent Document 1, as a result of considering suppression of misfire and the like based on a decrease in fuel pressure when only the in-cylinder injection control at the start is performed, the intake path injection control at the start is performed. The deterioration of fuel consumption due to an increase in the fuel injection amount by the start-up intake path injection control and the deterioration of emission are not taken into consideration, and the suppression of the deterioration of the fuel consumption and the emission is not sufficient.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a fuel injection control device capable of improving fuel efficiency and suppressing emission deterioration while ensuring at least startability. To do.

In order to solve the above-described problems and achieve the object, according to the present invention, an intake path fuel injection valve that injects fuel into an intake path of an internal combustion engine and an in-cylinder fuel injection valve that injects fuel into the cylinder of the internal combustion engine In the fuel injection control device for performing the fuel injection control according to the above, at the start of the start of the internal combustion engine, the fuel is supplied to the internal combustion engine by injection only by the in-cylinder fuel injection valve in the compression stroke of the internal combustion engine Division in which time cylinder injection control is performed, and after the start cylinder injection control, the fuel is supplied to the internal combustion engine by injection by the intake path fuel injection valve and injection by the cylinder fuel injection valve in the compression stroke A negative pressure in which an increase in negative pressure in the intake path is delayed from a normal increase in negative pressure during startup of the internal combustion engine during injection control If a temperature lag state, said internal combustion engine to supply cylinder compression stroke injection control of fuel injection amount set injection control by injection only by the in-cylinder fuel injection valve in the compression stroke of the internal combustion engine It is characterized by performing.

  In the fuel injection control device, when the negative pressure rise delay state, it is preferable to switch the injection control to the split injection control after maintaining the injection control in the in-cylinder compression stroke injection control for a predetermined period.

  Further, in the present invention, the fuel injection control device that performs the fuel injection control by the intake path fuel injection valve that injects fuel into the intake path of the internal combustion engine and the in-cylinder fuel injection valve that injects fuel into the cylinder of the internal combustion engine. The fuel injection amount setting means for setting the fuel injection amount of the internal combustion engine, and the increase correction means for increasing the fuel injection amount corresponding to the intake path fuel injection valve among the set fuel injection amounts, And at the start of the internal combustion engine, performing in-cylinder injection control at start time for supplying the fuel to the internal combustion engine by injection only by the in-cylinder fuel injection valve in the compression stroke of the internal combustion engine. After the in-cylinder injection control, the internal combustion is performed by injecting the fuel of the set fuel injection amount by the intake path fuel injection valve and by the in-cylinder fuel injection valve in the compression stroke. And the increase correction means performs the increase correction during the split injection control, and an increase in the negative pressure in the intake path during startup of the internal combustion engine is during startup of the internal combustion engine. When the negative pressure rise delay state is delayed from the normal rise of the negative pressure in the engine, the fuel injection amount corresponding to the intake path fuel injection valve is larger than that in the negative pressure rise delay state. It is characterized by performing an increase correction.

  In the fuel injection control device according to the present invention, when the internal combustion engine is started, first, the in-cylinder injection control at the start time is performed to increase the engine speed, and after the intake pressure is decreased, the split injection control is performed. The fuel injected by the injection valve is reliably introduced into the cylinder, and together with the fuel injected by the cylinder fuel injection valve, the air-fuel mixture in the vicinity of the spark plug is made richer than the air-fuel mixture in other areas in the cylinder. On the other hand, a weak stratified mixture that is weak throughout the cylinder (the mixture in the vicinity of the spark plug is richer than the homogeneous mixture, and the mixture in other areas in the cylinder is leaner than the stratified mixture) Can be generated). That is, the combustion mode at the start of the internal combustion engine is switched from stratified combustion to weakly stratified combustion. Therefore, when the spark plug is ignited, the air-fuel mixture in the vicinity of the spark plug is reliably ignited, and the air-fuel mixture in the entire cylinder can be reliably burned. As a result, the air-fuel mixture in the vicinity of the spark plug can be prevented from becoming richer beyond the combustible range, so that the air-fuel mixture in the entire cylinder can be prevented from becoming leaner, and HC (hydrocarbon) emissions can be reduced. Increase can be suppressed. In addition, since the fuel of the set fuel injection amount is divided and injected by the intake path fuel injection valve and the in-cylinder fuel injection valve, the piston wet is increased as compared with the case of only the in-cylinder injection control at the start. The emission can be suppressed, and the increase in smoke (black smoke) emission can be suppressed here. Further, compared with the case of only the in-cylinder injection control at the time of starting, it is possible to suppress a decrease in the pressure of the fuel supplied to the in-cylinder fuel injection valve, and among the fuel injection amounts set during the divided injection control A fuel injection amount corresponding to the in-cylinder fuel injection valve can be reliably injected by the in-cylinder fuel injection valve. Further, since the fuel of the set fuel injection amount is divided and injected by the intake path fuel injection valve and the in-cylinder fuel injection valve, the mist in the heavy fuel is compared with the case of only the intake path injection control at the time of starting. The influence by deterioration of vaporization and vaporization can be suppressed, and the increase in port wet can be suppressed. As a result, it is possible to improve fuel efficiency and suppress emission deterioration while ensuring startability.

  Further, in the fuel injection control device according to the present invention, when the negative pressure rise delay state is set, the place where the injection control is normally switched from the start-time in-cylinder injection control to the divided injection control is referred to as in-cylinder compression stroke injection control. That is, the supply of fuel to the internal combustion engine by only the in-cylinder fuel injection valve is maintained. Here, in the negative pressure rising delay state, the fuel adhering to the intake path increases among the fuel injected by the intake path fuel injection valve, that is, the port wet increases, and is injected by the intake path fuel injection valve. Combustion may be deteriorated by reducing the amount of fuel introduced into the cylinder. However, in the present invention, in the negative pressure rise delay state, in-cylinder compression stroke injection control is performed and fuel is not injected by the intake path fuel injection valve, so that deterioration of combustion can be suppressed. There is an effect.

  Further, in the fuel injection control device according to the present invention, the fuel injection amount corresponding to the intake path fuel injection valve is larger in the negative pressure rise delay state than in the negative pressure rise delay state. Even if wet increases, it is possible to suppress a reduction in the amount of fuel injected by the intake path fuel injection valve that is introduced into the cylinder, and to suppress deterioration of combustion. Play.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same.

[Embodiment 1]
FIG. 1 is a diagram illustrating a configuration example of an internal combustion engine according to a first embodiment. As shown in the figure, the internal combustion engine 1-1 according to the first embodiment includes a fuel supply device 2 and a plurality of cylinders 30a to 30d (in-line four cylinders in the first embodiment). 3, a valve device 4, an intake path 5 connected to the internal combustion engine body 3, an exhaust path 6 connected to the internal combustion engine body 3, and an ECU 7 that is a control device that controls the operation of the internal combustion engine 1-1. It is comprised by. Reference numeral 8 denotes an accelerator opening sensor that detects an accelerator opening that is an opening of an accelerator pedal operated by a driver (not shown) and outputs the detected accelerator opening to the ECU 7.

  The fuel supply device 2 supplies fuel stored in the fuel tank 23, for example, gasoline, to the internal combustion engine 1-1. The fuel supply device 2 includes an intake path fuel injection valve 21, an in-cylinder fuel injection valve 22, a fuel tank 23, a PFI fuel pump 24 that is a low-pressure fuel pump, a DI fuel pump 25 that is a high-pressure fuel pump, and a PFI. A PFI fuel pipe 26 connecting the fuel pump 24 and the intake path fuel injection valve 21; a branch pipe 27 connecting the PFI fuel pipe 26 and the DI fuel pump 25; a DI fuel pump 25 and an in-cylinder fuel injection valve 22; The DI fuel pipe 28 and the DI fuel pressure sensor 29 are connected to each other.

  The in-cylinder fuel injection valve 22 (hereinafter, simply referred to as “DI22”) is provided corresponding to each cylinder 30a to 30d of the internal combustion engine body 3, and the in-cylinder of each cylinder 30a to 30d. That is, fuel is supplied to the internal combustion engine 1-1 by injecting fuel in the fuel tank 23 pressurized by the PFI fuel pump 24 and the DI fuel pump 25 into the combustion chamber A, respectively. Each DI 22 is connected to the ECU 7, and control of the fuel injection amount and injection timing by the DI 22, that is, injection control is performed by the ECU 7.

  The intake path fuel injection valve 21 (hereinafter sometimes simply referred to as “PFI21”) is provided corresponding to each cylinder 30a to 30d of the internal combustion engine body 3, and the intake path of the internal combustion engine 1-1. 5. Here, the fuel in the fuel tank 23 pressurized by the PFI fuel pump 24 is injected into the intake port 37 formed in the cylinder head 32 corresponding to each of the cylinders 30a to 30d. -1 is supplied with fuel. Each PFI 21 is connected to the ECU 7, and control of the fuel injection amount and injection timing by the PFI 21, that is, injection control is performed by the ECU 7.

  The fuel tank 23 stores fuel. The fuel stored in the fuel tank 23 is pressurized by the PFI fuel pump 24 and discharged to the PFI fuel pipe 26 as PFI fuel. Therefore, the PFI fuel is supplied to each PFI 21 via the PFI fuel pipe 26 and is supplied to the DI fuel pump 25 via the PFI fuel pipe 26 and the branch pipe 27.

  The DI fuel pump 25 further pressurizes the PFI fuel. The DI fuel pump 25 is driven, for example, by rotation of a pump drive cam (not shown) attached to the intake cam shaft 43 of the valve device 4. The intake camshaft 43 rotates in conjunction with the rotation of the crankshaft 35. That is, the DI fuel pump 25 is driven by the output of the internal combustion engine 1-1.

  The DI fuel pump 25 is provided with an electromagnetic spill valve (not shown). The amount of PFI fuel flowing into the DI fuel pump 25 is adjusted by the electromagnetic spill valve, and pressurized by the DI fuel pump 25. The pressure of the DI fuel discharged to the DI pipe 28 is adjusted. Here, the electromagnetic spill valve is connected to the ECU 7, and the duty ratio is controlled by the ECU 7. Therefore, control of the pressure of DI fuel discharged from the DI fuel pump 25, that is, pressure control is performed by the ECU 7 using an electromagnetic spill valve (not shown).

  The DI fuel pressure sensor 29 is a pressure detection means and detects a DI fuel pressure P that is the pressure of the DI fuel. The DI fuel pressure sensor 29 is provided in the DI fuel pipe 28 and can detect DI fuel pressurized by the DI fuel pump 25 via the DI fuel pipe 28 and supplied to each DI 22. The DI fuel pressure sensor 29 is connected to the ECU 7, and the detected DI fuel pressure P is output to the ECU 7.

  The internal combustion engine body 3 includes a cylinder block 31, a cylinder head 32 fixed to the cylinder block 31, pistons 33 provided corresponding to the cylinders 30a to 30d, connecting rods 34 to be connected, a crankshaft 35, A spark plug 36 is provided for each of the cylinders 30a to 30d. Here, in each of the cylinders 30 a to 30 d of the internal combustion engine body 3, a combustion chamber A is formed by the piston 33, the cylinder block 31, and the cylinder head 32. In the cylinder head 32, an intake port 37 and an exhaust port 38 are formed corresponding to each of the cylinders 30a to 30d, and are connected to the intake path 5 and the exhaust path 6, respectively. Each piston 33 is rotatably supported by a connecting rod 34, and each connecting rod 34 is rotatably supported by a crankshaft 35. In other words, the crankshaft 35 rotates as each piston 33 reciprocates in the cylinder block 31 when the air-fuel mixture composed of the intake air and fuel in the combustion chamber A burns. is there. Each intake port 37 constitutes a part of the intake path 5, and each exhaust port 38 constitutes a part of the exhaust path 6.

  The spark plugs 36 are provided corresponding to the cylinders 30a to 30d, respectively, and ignite and ignite the air-fuel mixture in the combustion chamber A of the cylinders 30a to 30d. Each spark plug 36 is connected to the ECU 7, and control such as ignition timing, that is, ignition control is performed by the ECU 7. Reference numeral 39 denotes a crank angle sensor that detects a crank angle (CA) that is an angle of the crankshaft 35 and outputs the detected crank angle (CA) to the ECU 7. The ECU 7 calculates the engine speed of the internal combustion engine 1-1 from the crank angle detected by the crank angle sensor 39 and determines the cylinder of each of the cylinders 30a to 30d.

  The valve device 4 opens and closes the intake valve 41 and the exhaust valve 42. The valve device 4 includes an intake valve 41 and an exhaust valve 42, an intake camshaft 43, an exhaust camshaft 44, and an intake valve timing mechanism 45 that are provided corresponding to the cylinders 30a to 30d. . Each intake valve 41 is disposed between the intake port 37 and the combustion chamber A, and is opened and closed as the intake camshaft 43 rotates. Each exhaust valve 42 is disposed between the exhaust port 38 and the combustion chamber A, and is opened and closed by the rotation of the exhaust camshaft 44. The intake camshaft 43 and the exhaust camshaft 44 are connected to the crankshaft 35 through transmission means such as a timing chain, and rotate in conjunction with the rotation of the crankshaft 35.

  The intake valve timing mechanism 45 is disposed between the intake camshaft 43 and the crankshaft 35. The intake valve timing mechanism 45 is a continuously variable valve timing mechanism that continuously changes the phase of the intake camshaft 43. Further, the valve device 4 is provided with an intake cam position sensor 46, which detects the rotational position of the intake cam shaft 43 and outputs it to the ECU 7. The valve device 4 adjusts the opening / closing timing of the intake valve 41 by the intake valve timing mechanism 45. However, the present invention is not limited to this. For example, an exhaust valve timing mechanism for adjusting the opening / closing timing of the exhaust valve 42 is provided. May also be provided.

  The intake path 5 takes in air from the outside and introduces the drawn air into the combustion chamber A of each cylinder 30 a to 30 d of the internal combustion engine body 3. The intake passage 5 includes an air cleaner 51, an air flow meter 52, a throttle valve 53, and an intake passage 54 that communicates from the air cleaner 51 to the intake ports 37 of the cylinders 30a to 30d. The intake air from which dust has been removed by the air cleaner 51 is introduced into the combustion chambers A of the cylinders 30a to 30d through the intake passages 54 and the intake ports 37. The air flow meter 52 is an intake air amount detection means, which is introduced into each cylinder 30a to 30d, that is, detects the intake air amount sucked from the intake passage 5, and outputs it to the ECU 7. The throttle valve 53 adjusts the amount of intake air taken in from the intake path 5. The throttle valve 53 is driven by an actuator 53a such as a stepping motor. The actuator 53a is connected to the ECU 7, and control of the valve opening of the throttle valve 53, that is, valve opening control is performed by the ECU 7. The slot valve 53 is provided with a throttle valve sensor 53b. The slot valve sensor 53b detects the valve opening degree of the slot valve 53 and outputs it to the ECU 7.

  The exhaust path 6 includes a catalyst 61, a silencer (not shown), an exhaust passage 62 communicating from the exhaust port 38 of each cylinder 30a to 30d to the silencer via the catalyst 61, and an A / F sensor 63. It is configured. The catalyst 61 purifies harmful substances such as nitrided oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC) contained in the exhaust gas sucked through the exhaust passage 62. The catalyst 61 can adsorb sulfur (S) contained in the exhaust gas. The sulfur adsorption capacity of the catalyst 61, that is, the maximum sulfur adsorption amount is decreased as the catalyst temperature T increases. The exhaust gas from which harmful substances have been purified is exhausted from the catalyst 61 to the outside through an exhaust passage and a silencer (not shown).

  The A / F sensor 63 is air-fuel ratio detection means, and is disposed upstream of the catalyst 61 in the exhaust passage 62. The A / F sensor 63 detects the exhaust gas air-fuel ratio of the exhaust gas before being sucked into the catalyst 61 out of the exhaust gas exhausted from each combustion chamber A to the exhaust path 6 and outputs it to the ECU 7. . The ECU 7 calculates the air-fuel ratio of the internal combustion engine 1-1, that is, the ratio of air to fuel in the air-fuel mixture in the combustion chamber A based on the exhaust gas air-fuel ratio detected by the A / F sensor 63. That is, the A / F sensor 63 can detect the air-fuel ratio of the internal combustion engine 1-1.

  The ECU 7 operates the internal combustion engine 1-1 by controlling the operation of the internal combustion engine 1-1. The ECU 7 is also a fuel injection control device and executes a fuel injection control method described later. The ECU 7 receives various input signals from sensors attached to various parts of the vehicle on which the internal combustion engine 1-1 is mounted. Specifically, the DI fuel pressure P detected by the DI fuel pressure sensor 29, the crank angle detected by the crank angle sensor 39, the rotational position of the intake cam shaft 43 detected by the intake cam position sensor 46, and the air flow meter 52 The intake air amount detected by the accelerator opening degree, the accelerator opening degree detected by the accelerator opening degree sensor 8, the exhaust gas air-fuel ratio detected by the A / F sensor 63, and the like.

  The ECU 7 outputs various output signals based on these input signals and various maps such as a fuel injection amount map based on the intake air amount and the accelerator opening stored in the storage unit 73. Specifically, there are an injection signal for controlling the injection of each PFI 21 and each DI 22, an ignition signal for controlling the ignition of each spark plug 36, a valve opening signal for controlling the valve opening of the throttle valve 53, and the like.

  The ECU 7 includes an input / output unit (I / O) 71 that inputs and outputs the input signal and output signal, a processing unit 72, and a storage unit 73 that stores various maps such as a fuel injection amount map. Has been. The processing unit 72 includes a memory and a CPU (Central Processing Unit). The processing unit 72 has at least functions as a fuel injection amount setting unit 74, a start-time in-cylinder injection control unit 75, a split injection control unit 76, an increase correction unit 78, and a negative pressure increase determination unit 79. Yes. The processing unit 72 realizes the fuel injection control method by the ECU 7 by loading a program based on the operation method of the internal combustion engine 1-1, particularly the fuel injection control method by the ECU 7, and executing the program. Also good. The storage unit 73 is a non-volatile memory such as a flash memory, a memory that can be read only such as a ROM (Read Only Memory), or a memory that can be read and written such as a RAM (Random Access Memory). It can comprise by the combination of these.

  The fuel injection amount setting unit 74 is a fuel injection amount setting means, and sets the fuel injection amount Q for each of the cylinders 30a to 30d in the first embodiment, that is, the fuel injection amount of the internal combustion engine 1-1. That is, the fuel injection amount setting unit 74 sets the fuel injection amount Q by at least one of the PFI 21 and DI 22 corresponding to each of the cylinders 30a to 30d. The fuel injection amount setting unit 74 is basically set based on the engine speed Ne and the detected accelerator opening based on the detected crank angle.

  The start-time in-cylinder injection control unit 75 injects only each DI 22 in the compression stroke of the internal combustion engine 1-1 at the start of the start of the internal combustion engine 1-1, thereby setting the fuel injection set by the fuel injection amount setting unit 74. In-cylinder injection control at start-up, which is injection control for supplying an amount Q of fuel to the internal combustion engine 1-1, is performed. In the first embodiment, the in-cylinder injection control at start-up is an injection control in which fuel of a DI injection amount Q2, which is a set fuel injection amount Q, is supplied to the internal combustion engine 1-1 by a single injection by DI22. The start-time in-cylinder injection control unit 75 also performs ignition control of each spark plug 36, and performs the ignition control so that the ignition timing is advanced with respect to the normal time during the start-time in-cylinder injection control. The start-time in-cylinder injection control unit 75 also performs valve opening control of the throttle valve 53, and at the time of start-up in-cylinder injection control, the valve opening becomes an optimum valve opening for start-up in-cylinder injection control. Thus, the valve opening degree control is performed. The start-time in-cylinder injection control unit 75 sets the injection timing of the DI 22 so that the fuel of the fuel injection amount Q set only by the DI 22 can be injected in the compression stroke of the internal combustion engine 1-1. Further, the set fuel injection amount Q in the start-time in-cylinder injection control is a constant value.

  Here, in the first embodiment, the start-time in-cylinder injection control unit 75 starts the start-time in-cylinder injection control when the DI fuel pressure P detected by the DI fuel pressure sensor 29 becomes equal to or higher than a predetermined pressure P1 set in advance. I do. Here, the predetermined pressure P1 is equal to or higher than a pressure at which at least the fuel of the set fuel injection amount Q can be injected by each DI 22 at the time of starting in-cylinder injection control. In other words, the start-time in-cylinder injection control unit 75 starts the start of the internal combustion engine 1-1 when the DI 22 can inject fuel of the fuel injection amount Q set at the time of start-up in-cylinder injection control. When it is time, in-cylinder injection control is performed at start-up.

  After the start-time in-cylinder injection control by the start-time in-cylinder injection control unit 75, the split injection control unit 76 injects each PFI 21 in, for example, the intake stroke of the internal combustion engine 1-1 and each DI 22 in the compression stroke. Divided injection control, which is injection control for supplying the fuel of the fuel injection amount Q set by the fuel injection amount setting unit 74 to the internal combustion engine 1-1, is performed. That is, the split injection control is an injection control in which the fuel of the set fuel injection amount Q is divided and injected by the PFI 21 and DI22. In the first embodiment, the split injection control supplies the fuel of the PFI injection amount Q1, which is the fuel injection amount corresponding to the PFI 21, out of the set fuel injection amount Q to the internal combustion engine 1-1 by one injection by the PFI 21. In addition, this is the injection control in which the fuel of the DI injection amount Q2 that is the fuel injection amount corresponding to DI22 out of the set fuel injection amount Q is supplied to the internal combustion engine 1-1 by one injection by DI22. The divided injection control unit 76 also performs ignition control of each ignition plug 36, and performs ignition control so that the ignition timing is advanced with respect to the normal time during the divided injection control. The split injection control unit 76 also performs valve opening control of the throttle valve 53, and performs valve opening control so that the valve opening becomes the optimum valve opening for the split injection control during the split injection control. It is. The split injection control unit 76 sets the injection timing of each PFI 21 so that the fuel of the PFI injection amount Q1 can reach each combustion chamber A by the PFI 21 in the intake stroke of the internal combustion engine 1-1. The injection timing of DI 22 is set so that DI 22 can inject fuel of DI injection amount Q2 in one compression stroke.

  Here, in the first embodiment, when the switching condition is satisfied, the split injection control unit 76 switches from the start-time in-cylinder injection control to the split injection control and performs the split injection control. Here, the switching condition is set based on at least one of the intake pressure in the intake passage 5 (in-cylinder pressure in each combustion chamber A) and the physical quantity that affects the intake pressure. In the first embodiment, the engine speed of the internal combustion engine 1-1, which is a physical quantity that affects the intake pressure, is used as the switching condition, and switching is performed when the detected engine speed Ne is equal to or higher than the first predetermined speed Ne1. Suppose the condition is met. Note that the physical quantity that affects the intake pressure is not limited to the engine speed, but depends on the number of fuel injections of DI 22 (the engine speed increases and the intake pressure decreases as the number of injections increases), and DI 22 It may be an elapsed time from the start of fuel injection (with the passage of time, the number of injections increases, the engine speed increases, and the intake pressure decreases). In this case, it is assumed that the switching condition is satisfied when the number of injections is equal to or greater than the first predetermined number of injections, or when the first predetermined time or more has elapsed from the start of fuel injection by the DI 22. Here, at the first predetermined rotation speed, the first predetermined number of injections, and the first predetermined time, the negative pressure is sufficiently generated in the intake passage 5, and the fuel injected by each PFI 21 flows into each combustion chamber A. Is set to a value that can be. The switching condition may be satisfied when the plurality of conditions are satisfied.

  The in-cylinder compression stroke injection control unit 77 sets the fuel injection amount by injecting only each DI 22 in the compression stroke of the internal combustion engine 1-1 after the start-up in-cylinder injection control by the start-up in-cylinder injection control unit 75. In-cylinder compression stroke injection control, which is injection control for supplying fuel of the fuel injection amount Q set by the section 74 to the internal combustion engine 1-1, is performed. In the first embodiment, the in-cylinder compression stroke injection control is an injection control in which fuel of a DI injection amount Q2, which is a set fuel injection amount Q, is supplied to the internal combustion engine 1-1 by a single injection by DI22. The in-cylinder compression stroke injection control unit 75 also performs ignition control of each spark plug 36. The in-cylinder compression stroke injection control unit 77 also controls the valve opening of the throttle valve 53, and the valve opening becomes the optimum valve opening for the in-cylinder compression stroke injection control during the in-cylinder compression stroke injection control. Thus, the valve opening degree control is performed. The in-cylinder compression stroke injection control unit 77 sets the injection timing of DI 22 so that fuel of the fuel injection amount Q set only by DI 22 can be injected in the compression stroke of the internal combustion engine 1-1. The fuel injection amount Q set in the in-cylinder compression stroke injection control is set based on, for example, the intake air amount detected by the air flow meter 52 and output to the ECU 7.

  The increase correction unit 78 is an increase correction unit, and during the divided injection control by the divided injection control unit 76, among the set fuel injection amounts Q, the PFI injection amount Q1, which is the fuel injection amount corresponding to each PFI 21, is increased and corrected. To do. Here, the correction amount α is set based on the fuel adhering to the intake passage 5, that is, port wet, at the time of the first injection of each PFI 21. Here, the increase correction unit 78 sets the correction amount by decreasing the reference correction amount set at the start of the divided injection control with the passage of time.

  The negative pressure increase determination unit 79 determines whether or not the internal combustion engine 1-1 is in a negative pressure increase delay state. The negative pressure increase determination unit 79 determines whether or not the increase in the negative pressure in the intake passage 5 during the startup of the internal combustion engine 1-1 is delayed from the increase in the normal negative pressure during the startup of the internal combustion engine 1-1. It is determined whether or not the internal combustion engine 1-1 is in a negative pressure rise delay state. In the first embodiment, the negative pressure increase determination unit 79 is detected by the slot valve sensor 53b, and the internal combustion engine 1-1 is in a negative pressure increase delay state based on the valve opening degree of the slot valve 53 output to the ECU 7. Whether or not. The negative pressure increase determination unit 79 determines whether the internal combustion engine 1-1 is in a negative pressure increase delay state by determining abnormality of the throttle valve 53 based on the detected valve opening. Here, if the valve opening of the throttle valve 53 during the startup of the internal combustion engine 1-1 is larger than the normal valve opening during the startup of the internal combustion engine 1-1, an increase in the negative pressure in the intake passage 5 is caused. It will be delayed from the increase of the normal negative pressure during the start of 1-1. Therefore, the negative pressure increase determination unit 79 determines that the valve opening detected during startup of the internal combustion engine 1-1 is larger than the normally detected valve opening during startup of the internal combustion engine 1-1. Thus, it is determined that the internal combustion engine 1-1 is in the negative pressure rise delay state.

  Next, an operation method of the internal combustion engine 1-1 according to the first embodiment, that is, a fuel injection control method by the ECU 7 which is a fuel injection control device will be described. FIG. 2 is a diagram illustrating an operation flow of the fuel injection control apparatus according to the first embodiment. In addition, the fuel injection control method by ECU7 is performed for every control period of ECU7.

  First, as shown in FIG. 2, the processing unit 72 of the ECU 7 determines whether or not there is a request for starting the internal combustion engine 1-1 (step ST101). Here, for example, the processing unit 72 determines whether or not there is a request for starting the internal combustion engine 1-1 by turning on / off an ignition (start switch) (not shown) by the driver.

  Next, when determining that there is a request for starting the internal combustion engine 1-1 (Yes in Step ST101), the processing unit 72 starts increasing the pressure of DI fuel (Step ST102). Here, the processing unit 72 first drives and controls a starter (not shown) (electric motor in the case of a hybrid vehicle) to forcibly rotate the internal combustion engine 1-1 in which the starter and the crankshaft 35 are connected. As a result, the DI fuel pump 25 is driven. Next, the processing unit 72 controls the pressure of the DI fuel pump 25 to be driven (controls an electromagnetic spill valve (not shown) with a constant duty ratio), pressurizes the PFI fuel by the DI fuel pump 25, and supplies the DI fuel pipe 28. Discharge and pressurize DI fuel. Here, the pressure increase of the DI fuel is detected by the crank angle sensor 39 and is performed before the crank angle of the internal combustion engine 1-1 is determined, and the DI fuel is quickly started from the start of rotation by the starter of the internal combustion engine 1-1 for starting. Increase pressure. If the processing unit 72 determines that there is no request for starting the internal combustion engine 1-1 (No in step ST101), the processing unit 72 ends the current control cycle and shifts to the next control cycle.

  Next, the processing unit 72 determines whether or not the DI fuel pressure P is equal to or higher than a predetermined pressure P1 (step ST103). Here, the processing unit 72 determines whether or not the DI fuel pressure P detected by the DI fuel pressure sensor and acquired by the ECU 7 is equal to or higher than the predetermined pressure P1, thereby starting the internal combustion engine 1-1. It is determined whether or not. If the processing unit 72 determines that the DI fuel pressure P is less than the predetermined pressure P1 (No in step ST103), the processing unit 72 increases the DI fuel by the DI fuel pump 25 until the DI fuel pressure P becomes equal to or higher than the predetermined pressure P1. To do.

  Next, when the processing unit 72 determines that the DI fuel pressure P is equal to or higher than the predetermined pressure P1 (Yes in Step ST103), the processing unit 72 determines whether or not a switching condition is satisfied (Step ST104). Here, the processing unit 72 determines whether or not the switching condition is satisfied by determining whether or not the detected engine speed Ne is equal to or greater than the first predetermined speed Ne1.

  Next, when it is determined that the switching condition is not satisfied (No in step ST104), the start-time in-cylinder injection control unit 75 performs start-time in-cylinder injection control (step ST105). Here, the in-cylinder injection control unit 75 at the start time has the DI fuel pressure P equal to or higher than the predetermined pressure P1 and the switching condition is not satisfied, that is, the detected engine speed Ne is less than the first predetermined speed Ne1. If there is, start-up cylinder injection control is performed. In other words, the start-time in-cylinder injection control unit 75 injects the fuel of the DI injection amount Q2 that is the fuel injection amount Q set by the fuel injection amount setting unit 74 by each DI 22 in the compression stroke of the internal combustion engine 1-1. The injection control supplied to the internal combustion engine 1-1 is performed. Therefore, a stratified mixture is generated in each combustion chamber A, stratified combustion is performed, and the engine speed Ne of the internal combustion engine 1-1 is increased by an explosion in each combustion chamber A. Note that when the start-time in-cylinder injection control unit 75 performs the start-time in-cylinder injection control, the processing unit 72 ends the current control cycle and shifts to the next control cycle.

  Further, when it is determined that the switching condition is satisfied (Yes in step ST104), the negative pressure increase determination unit 79 determines whether or not the internal combustion engine 1-1 is in a negative pressure increase delay state (step ST106). ). Here, the negative pressure increase determination unit 79 detects whether or not the valve opening detected by the throttle valve sensor 53b and acquired by the ECU 7 is larger than the normal valve opening at the start of the internal combustion engine 1-1. By determining whether or not the throttle valve 53 is abnormal, it is determined whether or not the internal combustion engine 1-1 is in a negative pressure rise delay state. That is, the negative pressure increase determination unit 79 determines whether or not the internal combustion engine 1-1 is in a negative pressure increase delay state while maintaining the in-cylinder injection control at the start.

  Next, when it is determined by the negative pressure increase determination unit 79 that the negative pressure increase delay state is not in effect (No in step ST106), the split injection control unit 76 performs the increase correction of the PFI injection amount Q1 by the increase correction unit 78, and increases the increase. Division injection control is performed based on the corrected PFI injection amount Q1 (step ST107). In other words, the split injection control unit 76 satisfies the switching condition, the throttle valve 53 is normal, and the increase in the negative pressure in the intake passage 5 when the internal combustion engine 1-1 is started is normal when the internal combustion engine 1-1 is started. When the negative pressure increases, split injection control is performed. Here, the increase correction unit 78 sets a correction amount α to be added to the PFI injection amount Q1. The split injection control unit 76 supplies the fuel of the PFI injection amount Q1 to which the correction amount α set by the increase correction unit 78 is added to the internal combustion engine 1-1 by a single injection by the PFI 21, and the DI injection amount Q2 Injection control is performed to supply the fuel to the internal combustion engine 1-1 by a single injection by DI22. Accordingly, in each combustion chamber A, the fuel mixture injected by the PFI 21 and the fuel injected by the DI 22 cause the air-fuel mixture in the vicinity of the spark plug 36 to be richer than the other air-fuel mixture in the combustion chamber A. However, a weakly stratified mixture that is weak in the entire combustion chamber A (the mixture in the vicinity of the spark plug 36 is richer than the homogeneous mixture, and the mixture in other regions in the combustion chamber A is more mixed than the stratified mixture) The gas is on the lean side), weak stratified combustion is performed, and the engine speed Ne of the internal combustion engine 1-1 is increased by the explosion in each combustion chamber A. Further, even in a state where the fuel injected by the PFI 21 introduced into the combustion chamber A due to port wet is reduced, the fuel is injected into the combustion chamber A by the PFI 21 and corresponds to each PFI 21 among the set fuel injection amounts Q. Therefore, it is possible to reliably introduce the fuel having the PFI injection amount Q1, which is the fuel to be used. Note that when the divided injection control unit 76 performs the divided injection control, the processing unit 72 ends the current control cycle and shifts to the next control cycle.

  In-cylinder compression stroke injection control unit 77 performs in-cylinder compression stroke injection control (step ST108) when negative pressure increase determination unit 79 determines that the negative pressure increase delay state is present (Yes in step ST106). Here, the in-cylinder compression stroke injection control unit 77 performs the divided injection control by the normal divided injection control unit 76 when the negative pressure rise delay state is satisfied even if the switching condition is satisfied. I do. That is, in the negative pressure rise delay state, the DI22 is normally switched from the in-cylinder injection control to the in-cylinder compression stroke injection control in place of switching the injection control from the in-cylinder injection control to the divided injection control. Maintain fuel supply to the internal combustion engine with only injection. The in-cylinder compression stroke injection control unit 77 maintains the in-cylinder compression stroke injection control for a predetermined period. Here, the predetermined period is, for example, until the detected engine rotational speed Ne reaches the second predetermined rotational speed Ne2 (a value higher than the first predetermined rotational speed Ne1) or is negative by the negative pressure increase determination unit 79. After the pressure rise delay state is determined, the DI22 fuel injection count reaches the second predetermined injection count (for example, about several times).

  Next, after performing the in-cylinder compression stroke injection control, the split injection control unit 76 performs the increase correction of the PFI injection amount Q1 by the increase correction unit 78, and performs the split based on the PFI injection amount Q1 for which the increase correction has been performed. Injection control is performed (step ST107). Here, the divided injection control unit 76 performs the divided injection control even after the negative pressure increase determination unit 79 determines that the negative pressure increase is delayed (Yes in step ST106) and performs the in-cylinder compression stroke injection control. . That is, in the negative pressure rise delay state, the split injection control is performed after maintaining the in-cylinder compression stroke injection control for a predetermined period.

  As described above, the ECU 7 that is the fuel injection control device according to the first embodiment first increases the engine speed Ne by performing the in-cylinder injection control at the start of the internal combustion engine 1-1, and the intake pressure is increased. Since the split injection control is performed after the decrease, that is, the in-cylinder negative pressure rises, the fuel injected by the PFI 21 is reliably introduced into the combustion chamber A, and together with the fuel injected by the DI 22, the fuel is injected into the combustion chamber A. A weakly stratified mixture can be generated, and the combustion mode at the start of the internal combustion engine is switched from stratified combustion to weakly stratified combustion. Therefore, when the spark plug 36 is ignited, the air-fuel mixture in the vicinity of the spark plug 36 is reliably ignited, and the air-fuel mixture in the entire combustion chamber A can be reliably combusted. As a result, the air-fuel mixture in the vicinity of the spark plug 36 can be prevented from becoming richer beyond the combustible range, so that the air-fuel mixture in the entire combustion chamber A can be prevented from becoming leaner, and HC (hydrocarbon) The increase in the emission of can be suppressed. In addition, since the fuel of the set fuel injection amount is divided and injected into each PFI 21 and DI 22, the increase in piston wet can be suppressed and the emission deteriorated compared to the case of only the in-cylinder injection control at the start. Here, an increase in the emission of smoke (black smoke) can be suppressed. Further, compared with the case of only the in-cylinder injection control at the start time, it is possible to suppress a decrease in the pressure of the fuel supplied to the DI 22, and the fuel of the DI injection amount Q2 is reliably injected by the DI 22 at the time of the divided injection control. can do. Further, at the time of split injection control, the fuel of the set fuel injection amount Q is divided and injected by PFI 21 and DI 22, so that compared with the case of only the intake-path injection control at the time of starting, The influence by the deterioration of vaporization can be suppressed, and the increase in port wet can be suppressed. As a result, it is possible to improve fuel efficiency and suppress emission deterioration while ensuring startability.

  In addition, when fuel is divided and injected into PFI 21 and DI 22 by split injection control, fuel is injected only by DI 22 by in-cylinder compression stroke injection control instead of performing split injection control after start-up cylinder injection control Compared with the above, even if the actual fuel injection amount varies (for example, about ± 20%) with respect to the set fuel injection amount Q, the variation in torque generated in the internal combustion engine 1-1 with respect to the fuel injection amount is suppressed And increase in HC (hydrocarbon) emission can be suppressed. Therefore, robustness can be improved.

  Further, when the negative pressure rise is delayed, the injection control is usually switched from the in-cylinder injection control at the start time to the divided injection control, and the in-cylinder compression stroke injection control is performed, so that the fuel injection by only the DI 22 is performed. Since the fuel is not injected by the PFI 21, the deterioration of the combustion can be suppressed.

  Further, since the negative pressure increase determination unit 79 determines the negative pressure increase delay state without detecting the pressure in the intake passage 5, it is possible to suppress deterioration of combustion without requiring a pressure sensor or the like.

[Embodiment 2]
Next, an internal combustion engine 1-2 according to the second embodiment will be described. FIG. 3 is a diagram illustrating a configuration example of the internal combustion engine according to the second embodiment. The internal combustion engine 1-2 according to the second embodiment shown in FIG. 3 is different from the internal combustion engine 1-1 according to the first embodiment shown in FIG. 1 in that it corresponds to the PFI 21 when it is in a negative pressure rise delay state. The point is that the division injection control is performed by correcting the increase so that the PFI injection amount Q1, which is the fuel injection amount to be increased, is larger than that in the case of not being in the negative pressure rise delay state. Here, in the basic configuration of the internal combustion engine 1-2 according to the second embodiment shown in FIG. 3, the same parts as the basic configuration of the internal combustion engine 1-1 according to the first embodiment shown in FIG. Is omitted.

  The increase correction unit 78 corrects to increase the PFI injection amount Q1 during the divided injection control by the split injection control unit 76, but adds a different correction amount to the PFI injection amount Q1 depending on whether or not the negative pressure rise delay state. The increase correction unit 78 increases the correction amount β in the negative pressure increase delay state than the correction amount α in the negative pressure increase delay state. That is, the PFI injection amount Q1 that has been subjected to the increase correction is set to be larger in the negative pressure rise delay state than in the negative pressure rise delay state.

  Next, an operation method of the internal combustion engine 1-2 according to the second embodiment, particularly a fuel injection control method by the ECU 7 which is a fuel injection device will be described. FIG. 4 is a diagram illustrating an operation flow of the fuel injection control apparatus according to the second embodiment. Of the fuel injection control method according to the second embodiment shown in FIG. 4, the same or substantially the same part as the fuel injection control method according to the embodiment shown in FIG.

  First, as shown in FIG. 4, the processing unit 72 of the ECU 7 determines whether or not there is a request for starting the internal combustion engine 1-2 (step ST201).

  Next, when it is determined that there is a request for starting the internal combustion engine 1-2 (Yes in Step ST201), the processing unit 72 starts boosting DI fuel (Step ST202).

  Next, the processing unit 72 determines whether or not the DI fuel pressure P is equal to or higher than a predetermined pressure P1 (step ST203).

  Next, when determining that the DI fuel pressure P is equal to or higher than the predetermined pressure P1 (Yes in Step ST203), the processing unit 72 determines whether or not the switching condition is satisfied (Step ST204). Here, in the second embodiment, when the DI fuel pressure increased by the DI fuel pump 25 becomes equal to or higher than the predetermined pressure P1, the processing unit 72 causes the number of injections of each DI 22 to be equal to or higher than the first predetermined injection number (for example, once). It is determined whether or not the switching condition is satisfied by determining whether or not there is, that is, whether or not one cycle of the internal combustion engine 1-2 has been completed from the start of injection by DI22.

  Next, if it is determined that the switching condition is not satisfied (No in step ST204), the start-time in-cylinder injection control unit 75 performs start-time in-cylinder injection control (step ST205).

  Further, when it is determined that the switching condition is satisfied (Yes in step ST204), negative pressure increase determination unit 79 determines whether or not internal combustion engine 1-2 is in a negative pressure increase delay state (step ST206). ). The negative pressure increase determination unit 79 determines whether or not the internal combustion engine 1-2 is in a negative pressure increase delay state while maintaining the in-cylinder injection control at the start.

  Next, when it is determined by the negative pressure increase determination unit 79 that the negative pressure increase delay state is not in effect (No in step ST206), the split injection control unit 76 performs the increase correction of the PFI injection amount Q1 by the increase correction unit 78 to increase the increase. Divided injection control is performed based on the corrected PFI injection amount Q1 (step ST207). Here, the increase correction unit 78 sets a correction amount α to be added to the PFI injection amount Q1. The split injection control unit 76 supplies the fuel of the PFI injection amount Q1 (Q1 = Q1 + α) to which the correction amount α set by the increase correction unit 78 is added to the internal combustion engine 1-2 by one injection by the PFI 21, and Injection control is performed to supply the fuel of DI injection amount Q2 to the internal combustion engine 1-2 by one injection by DI22. Note that when the divided injection control unit 76 performs the divided injection control, the processing unit 72 ends the current control cycle and shifts to the next control cycle.

  Further, when the negative pressure increase determination unit 79 determines that the negative pressure increase delay state is present (Yes in step ST206), the divided injection control unit 76 increases the PFI injection amount Q1 by the increase correction unit 78 to increase the negative pressure. When it is not in the delayed state, it is performed so as to be larger than the PFI injection amount Q1 that has been subjected to the increase correction, and the divided injection control is performed based on the PFI injection amount Q1 that has been subjected to the increase correction (step ST208). Here, the increase correction unit 78 sets a correction amount β to be added to the PFI injection amount Q1. The split injection control unit 76 supplies the fuel of the PFI injection amount Q1 (Q1 = Q1 + β) to which the correction amount β set by the increase correction unit 78 is added to the internal combustion engine 1-2 by one injection by the PFI 21, and Injection control is performed to supply the fuel of DI injection amount Q2 to the internal combustion engine 1-2 by one injection by DI22. Here, the correction amount β is larger than the correction amount α, and is set so that the PFI injection amount Q1 before the increase correction can be introduced into the combustion chamber A when the negative pressure rise is delayed. Yes. That is, the correction amount β is set so that the difference between the correction amount β and the correction amount α is the difference in port wet between when the negative pressure rise delay state and when the negative pressure rise delay state is not. Note that when the divided injection control unit 76 performs the divided injection control, the processing unit 72 ends the current control cycle and shifts to the next control cycle.

  As described above, the ECU 7 that is the fuel injection control apparatus according to the second embodiment can improve the fuel consumption and suppress the deterioration of the emission while ensuring the startability as in the first embodiment. There is an effect. Moreover, robustness can be improved.

  Further, in the negative pressure rise delay state, the PFI injection amount Q1, which is the fuel injection amount corresponding to the PFI 21, is larger than that in the negative pressure rise delay state, so that even if the port wet increases, the PFI 21 It can suppress that the quantity introduce | transduced in a cylinder among the fuel injected by this is reduced, and can suppress that a combustion deteriorates.

  Further, since the negative pressure increase determination unit 79 determines the negative pressure increase delay state without detecting the pressure in the intake passage 5, it is possible to suppress deterioration of combustion without requiring a pressure sensor or the like.

  In the first and second embodiments, when the end condition is satisfied, the processing unit 72 may end the split injection control and perform the normal control as the injection control. The normal control is, for example, injection control that can supply the internal combustion engines 1-1 and 1-2 with a fuel injection amount that can maintain the operation of the internal combustion engines 1-1 and 1-2 that have been started. Here, the end condition is set based on at least one of a physical quantity that can be determined that the start of the internal combustion engines 1-1 and 1-2 has been completed and a physical quantity that can be determined that the divided injection control cannot be performed. is there. In the first and second embodiments, for example, the engine speed of the internal combustion engine 1-1 or 1-2, which is a physical quantity that can be determined that the start of the internal combustion engine 1-1 or 1-2 has been completed, is used as the end condition. It is assumed that the end condition is satisfied when the detected engine speed Ne is equal to or higher than the third predetermined speed Ne3 (a value higher than the first predetermined speed Ne1 and the second predetermined speed Ne2). The physical quantity that can be determined that the start of the internal combustion engine 1-1, 1-2 has been completed is not limited to the engine speed, but the number of DI22 fuel injections (the engine speed increases as the number of injections increases, It can be determined that the internal combustion engine 1-1, 1-2 has been started) and the elapsed time from the start of fuel injection by the DI 22 (the number of injections increases with the passage of time, the engine speed increases, and the internal combustion engine increases). 1-1, 1-2 can be determined to have been completed). In this case, if the number of injections is equal to or greater than a third predetermined number of injections (a value higher than the first predetermined number of injections and the second predetermined number of injections), or a second predetermined time (the first number of times described above) from the start of fuel injection by DI22. It is assumed that the end condition is satisfied when a value higher than 1 predetermined time) elapses. Here, the third predetermined rotation speed Ne3, the third predetermined number of injections, and the second predetermined time are set to values at which it can be determined that the start of the internal combustion engines 1-1 and 1-2 is completed. Further, as a termination condition, a load factor, that is, a physical quantity that can be determined that the divided injection control cannot be performed, that is, in-cylinder charging efficiency is used, and is estimated based on, for example, the detected engine speed Ne and the detected intake air amount. The termination condition may be satisfied if the applied load factor is equal to or less than a predetermined value. The physical quantity that can be determined that the divided injection control cannot be performed is not limited to the load factor, and is the fuel injection quantity corresponding to DI22 among the fuel injection quantities Q set by the fuel injection quantity setting unit 74. The DI injection amount Q2 or the PFI injection amount Q1 that is the fuel injection amount corresponding to the PFI 21 out of the fuel injection amount Q set by the fuel injection amount setting unit 74 may be used. In this case, the termination condition may be satisfied if the DI injection amount Q2 is less than the minimum injection amount of DI22 or the PFI injection amount Q1 is less than the minimum injection amount of PFI21. Further, the end condition may be satisfied when the plurality of conditions are satisfied.

  In the first and second embodiments, when the switching condition is satisfied, the PFI injection amount increase correction is performed by the increase correction unit 78, but the present invention is not limited to this. For example, the increase correction may be started when the switching condition is satisfied and the increase condition is satisfied. Here, it is assumed that the increase condition is satisfied when the number of injections of each PFI 21 is equal to or less than the fourth predetermined number of injections (for example, 3 times) as the increase condition. As the increasing condition, the water temperature of the cooling water of the internal combustion engine 1-1, 1-2 is used. For example, the water temperature detected by a water temperature sensor (not shown) and output to the ECU 7 is equal to or lower than a predetermined temperature, or fuel by each DI 22 It is assumed that the increase condition is satisfied when the third predetermined time or more has elapsed from the start of fuel injection by each DI 22 using the elapsed time from the start of injection. The increase condition may be satisfied when the plurality of conditions are satisfied.

  In the first and second embodiments, when the negative pressure increase determination unit 79 determines that the negative pressure increase is delayed, after the start-up in-cylinder injection control is continued, the divided injection control or the increase correction is performed. Although the divided injection control is performed, the present invention is not limited to this, and the divided injection control may be prohibited and the normal injection control may be performed. Further, it may be determined whether or not the negative pressure rise delay state is detected based on the negative pressure of the intake path 5 detected by the pressure sensor provided in the intake path 5 and output to the ECU 7.

  In the first and second embodiments, the negative pressure increase determination unit 79 determines whether or not the negative pressure increase delay state is based on the valve opening of the throttle valve 53, but the present invention is not limited to this. It may be any as long as it can determine whether or not it is in a negative pressure rise delay state.

  For example, when the EGR device that circulates a part of the exhaust gas in the exhaust path 6 to the intake path 5 is mounted in the internal combustion engines 1-1 and 1-2, the amount of exhaust gas flowing into the intake path 5 is controlled. The negative pressure rise delay state may be determined based on the EGR valve opening degree of the EGR valve. In this case, the negative pressure increase determination unit 79 determines whether or not the internal combustion engines 1-1 and 1-2 are in a negative pressure increase delay state by determining an abnormality of the EGR valve based on the detected EGR valve opening degree. Determine whether. Here, the EGR valve opening degree of the EGR valve during the startup of the internal combustion engine 1-1, 1-2 is larger than the normal EGR valve opening degree (normally closed) during the startup of the internal combustion engine 1-1, 1-2. Is larger, the increase in the negative pressure in the intake passage 5 is delayed from the normal increase in the negative pressure during the startup of the internal combustion engine 1-1. Accordingly, the negative pressure increase determination unit 79 determines that the EGR valve opening detected during startup of the internal combustion engines 1-1 and 1-2 is normally detected EGR during startup of the internal combustion engines 1-1 and 1-2. By determining that the opening is larger than the valve opening, it may be determined that the internal combustion engines 1-1 and 1-2 are in the negative pressure rise delay state.

  Further, for example, when a brake booster that assists the driver's operation from the negative pressure of the intake passage 5 is provided in a brake device that applies a braking force to a vehicle in which the internal combustion engines 1-1 and 1-2 are mounted. May be detected by a pressure sensor for detecting the pressure in the brake booster provided in advance, and the negative pressure rise delay state may be determined based on the brake booster negative pressure output to the ECU 7. Here, if the brake booster negative pressure during the startup of the internal combustion engine 1-1, 1-2 is smaller than the normal brake booster negative pressure during the startup of the internal combustion engine 1-1, 1-2, the driver Since the negative pressure in the intake passage 5 is used for the brake booster, the increase in the negative pressure in the intake passage 5 is delayed from the normal increase in the negative pressure during the startup of the internal combustion engine 1-1. . Therefore, the negative pressure increase determination unit 79 determines that the brake booster negative pressure detected during the startup of the internal combustion engines 1-1 and 1-2 is the normal detected brake during the startup of the internal combustion engines 1-1 and 1-2. By determining that the pressure is lower than the booster negative pressure, it may be determined that the internal combustion engines 1-1 and 1-2 are in a negative pressure rise delay state.

  As described above, the fuel injection control device includes the intake path fuel injection valve that injects fuel into the intake path of the internal combustion engine and the in-cylinder fuel injection valve that injects fuel into the cylinder of the internal combustion engine. It is useful for an injection control method, and is particularly suitable for improving fuel efficiency and suppressing emission deterioration while ensuring startability.

1 is a diagram illustrating a configuration example of an internal combustion engine according to a first embodiment. FIG. 3 is a diagram illustrating an operation flow of the fuel injection control apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of an internal combustion engine according to a second embodiment. It is a figure which shows the operation | movement flow of the fuel-injection control apparatus concerning Embodiment 2. FIG.

Explanation of symbols

1-1, 1-2 Internal combustion engine 2 Fuel supply device 21 Intake path fuel injection valve 22 In-cylinder fuel injection valve 3 Internal combustion engine body 4 Valve device 5 Intake path 53 Throttle valve 53b Throttle valve sensor 6 Exhaust path 7 ECU (fuel injection) Control device)
74 Fuel injection amount setting unit (fuel injection amount setting means)
75 In-cylinder injection control unit at start 76 Split injection control unit 77 In-cylinder compression stroke injection control unit 78 Increase correction unit (increase correction means)
79 Negative pressure rise determination part 8 Accelerator position sensor α, β Correction amount

Claims (3)

In a fuel injection control device that performs injection control of the fuel by an intake path fuel injection valve that injects fuel into an intake path of the internal combustion engine and an in-cylinder fuel injection valve that injects fuel into the cylinder of the internal combustion engine,
When starting the internal combustion engine, start-up cylinder injection control for supplying the fuel to the internal combustion engine by injection only by the cylinder fuel injection valve in the compression stroke of the internal combustion engine is performed.
After the start-time in-cylinder injection control, split injection control for supplying the fuel to the internal combustion engine by injection by the intake path fuel injection valve and injection by the in-cylinder fuel injection valve in the compression stroke is performed.
The injection control is set when the negative pressure rise in the intake path is delayed during the startup of the internal combustion engine and is delayed from the normal negative pressure rise during the startup of the internal combustion engine. A fuel injection control device that performs in-cylinder compression stroke injection control for supplying a fuel injection amount of fuel to the internal combustion engine by injection only by the in-cylinder fuel injection valve in the compression stroke of the internal combustion engine.   2. The fuel injection control device according to claim 1, wherein, in the negative pressure rise delay state, the injection control is switched to the split injection control after maintaining the in-cylinder compression stroke injection control for a predetermined period. In a fuel injection control device that performs injection control of the fuel by an intake path fuel injection valve that injects fuel into an intake path of the internal combustion engine and an in-cylinder fuel injection valve that injects fuel into the cylinder of the internal combustion engine,
Fuel injection amount setting means for setting the fuel injection amount of the internal combustion engine;
An increase correction means for increasing and correcting the fuel injection amount corresponding to the intake path fuel injection valve among the set fuel injection amounts;
With
When starting the internal combustion engine, start-up cylinder injection control for supplying the fuel to the internal combustion engine by injection only by the cylinder fuel injection valve in the compression stroke of the internal combustion engine is performed.
After the start-time in-cylinder injection control, split injection for supplying the set fuel injection amount to the internal combustion engine by injection by the intake path fuel injection valve and injection by the in-cylinder fuel injection valve in the compression stroke Control
The increase correction means performs the increase correction during the divided injection control, and the increase in the negative pressure in the intake path during startup of the internal combustion engine is higher than the normal increase in the negative pressure during startup of the internal combustion engine. The fuel increase correction is performed so that the fuel injection amount corresponding to the intake path fuel injection valve is increased in the case of a delayed negative pressure increase delay state as compared with the case where the negative pressure increase delay state is not in the negative pressure increase delay state. Injection control device.

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