JP2013209935A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device for an internal combustion engine that can further reduce discharged PN than a conventional device, the internal combustion engine allowing a direct-injection injector to perform in-cylinder injection.SOLUTION: A fuel injection control device is for an internal combustion engine, the internal combustion engine having cylinders and direct-injection injectors capable of injecting fuel into the cylinders, and if a temperature in the internal combustion engine is within a predetermined low-temperature range (step S2; YES, step S3; NO), fuel is injected from the direct-injection injector (step S7, step S11) in a compression stroke in a combustion cycle of the internal combustion engine.

Description

  The present invention relates to a fuel injection control device for an internal combustion engine.

  2. Description of the Related Art An internal combustion engine mounted on a vehicle such as an automobile is known that includes a direct injection injector that injects fuel into a cylinder and a port injection injector that injects fuel toward an intake port.

  A fuel injection control device that controls fuel injection of this type of internal combustion engine obtains a target fuel injection amount in the fuel injection when fuel injection is performed from a direct injection injector. This target fuel injection amount is set based on the required fuel injection amount in the entire internal combustion engine and the fuel injection ratio of the direct injector and the port injector that satisfy the required fuel injection amount. The required fuel injection amount and the injection ratio are set based on engine operating conditions such as engine speed and engine load. The fuel injection control device executes the fuel injection from the direct injection injector so as to obtain at least a part of the required fuel injection amount by driving the direct injection injector so as to obtain a predetermined target fuel injection amount. To do.

  In this type of internal combustion engine fuel injection control device, in-cylinder injection is performed from the direct injection injector during the compression stroke of the combustion cycle at the start of the internal combustion engine, and after the rotational speed of the internal combustion engine increases, In addition to injection, there is known one that performs port injection from a port injection injector (see, for example, Patent Document 1).

JP 2010-43602 A

  However, in the conventional fuel injection control device for an internal combustion engine, the injection method is not switched according to the temperature of the internal combustion engine. For this reason, for example, when the internal combustion engine is at a low temperature, fuel vaporization cannot be promoted, and the combustion state may deteriorate. In addition, this internal combustion engine fuel injection control device always performs in-cylinder injection in the compression stroke when the internal combustion engine is started, and does not take into consideration an appropriate temperature range and injection amount, thereby improving the combustion speed. There was a possibility that it could not be planned. In recent years, it has been desired to reduce PN, which is the number of PM (particulate matter) particles in exhaust gas. However, if the conventional fuel injection control device for an internal combustion engine cannot improve combustion speed, PN There is a problem that the effect of reducing the above cannot be obtained.

  The present invention has been made to solve such a problem, and in an internal combustion engine capable of performing in-cylinder injection by a direct injection injector, a fuel injection control device for an internal combustion engine capable of reducing discharged PN as compared with the prior art. The purpose is to provide.

  In order to achieve the above object, a fuel injection control device for an internal combustion engine according to the present invention includes: (1) fuel injection of an internal combustion engine that controls injection of the fuel from a direct injection injector capable of injecting fuel into a cylinder of the internal combustion engine. In the control device, when the temperature of the internal combustion engine is within a predetermined low temperature range, the fuel is injected from the direct injection injector in a compression stroke during a combustion cycle of the internal combustion engine.

  With this configuration, the fuel injection control device for the internal combustion engine injects fuel from the direct injection injector during the compression stroke when the temperature of the internal combustion engine is within a predetermined low temperature range. As a result, the fuel injection control device for the internal combustion engine can easily collect the injected fuel around the spark plug by the airflow in the cylinder, and the like, as compared with the case where the fuel is injected in the intake stroke. For this reason, the fuel injection control device of the internal combustion engine can improve the ignition of the fuel in the cylinder and increase the combustion speed of the fuel, so that the PN discharged from the internal combustion engine can be reduced.

  In the fuel injection control device for an internal combustion engine according to the above (1), (2) the fuel injection required for the injection in the compression stroke when the total amount of direct injection required for the fuel injection into the cylinder is When the amount is larger than the amount, the fuel is injected from the direct injector during the intake stroke in the combustion cycle by subtracting the fuel injection amount from the direct injection total injection amount.

  Here, in a fuel injection control device for an internal combustion engine, for example, in order to reduce deposit accumulation at the nozzles of a direct injection injector, a fuel injection amount that is greater than the fuel injection amount required for combustion in the compression stroke is directly increased. There is a case where it is required as a total injection amount.

  With the above-described configuration of the present invention, the fuel injection control device for an internal combustion engine can calculate the direct injection total injection amount even when a fuel injection amount equal to or greater than the fuel injection amount for combustion is required as the direct injection total injection amount. In-cylinder fuel can be injected in the intake stroke by subtracting the fuel injection amount for combustion. As a result, the fuel injection control device of the internal combustion engine in-cylinder-injects the fuel injection amount that exceeds the fuel injection amount for combustion in the direct injection total injection amount in the intake stroke preceding the compression stroke. Shift to compression stroke while maintaining homogeneity of fuel and air. Therefore, the fuel injection control device of the internal combustion engine can properly maintain the homogeneity of the fuel and air in the cylinder and the fuel injection amount in the compression stroke while reducing the deposit accumulation at the nozzle of the direct injection injector. A reduction in PN discharged from the internal combustion engine can be realized by increasing the speed.

  In the fuel injection control device for an internal combustion engine according to the above (1) or (2), (3) the internal combustion engine includes an intake port, a port injection injector capable of injecting the fuel toward the intake port, And the port injection injector injects the fuel for the port injection amount obtained by subtracting the total direct injection amount from the required fuel injection amount required for fuel injection to the internal combustion engine. Configure.

  With this configuration, the fuel injection control device for an internal combustion engine can be applied to an internal combustion engine that employs a dual type fuel injection system in which the internal combustion engine has two types of injectors, a direct injection injector and a port injection injector. Thereby, the fuel injection control device of the internal combustion engine performs port injection of the fuel corresponding to the port injection amount obtained by subtracting the total direct injection amount from the required fuel injection amount when the required fuel injection amount is larger than the direct injection total injection amount. be able to. Therefore, the fuel injection control device of the internal combustion engine can ensure the homogeneity of the fuel and air mixture by executing the port injection, and suppress the injection of excessive fuel from the direct injection injector, thereby deteriorating the combustion. Can be suppressed.

  In the fuel injection control device for an internal combustion engine described in (3) above, (4) when the temperature of the internal combustion engine is lower than the low temperature range, the fuel is injected only from the port injector. With this configuration, the fuel injection control device of the internal combustion engine stops in-cylinder injection when the internal combustion engine is in the cryogenic temperature range lower than the low temperature range, so that generation of PN can be suppressed as much as possible.

  Here, according to the fuel injection into the cylinder, PN reduction effect is obtained by injecting fuel to the top of the piston by fuel injection in the compression stroke and filling the air-fuel mixture around the spark plug and burning it. be able to. On the other hand, when the temperature of the internal combustion engine is in a very low temperature state lower than the low temperature range, the fuel that is injected in the compression stroke and hits the piston may directly adhere to the piston and become a PN generation source. For this reason, by adopting port injection in a cryogenic state, generation of PN can be suppressed as much as possible.

  In the fuel injection control device for an internal combustion engine described in (1) to (4) above, (5) the compression stroke is configured to be in the latter half of the compression stroke. Here, in the present specification, the latter stage of the compression stroke is a time near the top dead center in the compression stroke, and means, for example, the latter half of the time when the compression stroke is divided into two.

  With this configuration, the fuel injection control device of the internal combustion engine performs in-cylinder injection when the piston is close to top dead center, so that the time until combustion is shorter than in the first half of the compression stroke. For this reason, the fuel injection control device of the internal combustion engine concentrates the injected fuel at a high concentration around the ignition plug and burns it, and the combustion speed of the fuel can be further increased, so that the fuel is discharged from the internal combustion engine. PN can be further reduced.

  In the fuel injection control device for an internal combustion engine described in (2) above, (6) the intake stroke is configured to be in the first half of the intake stroke. Here, in the present specification, the first half of the intake stroke is a time near the top dead center in the intake stroke, and means, for example, the first half of the time when the intake stroke is divided into two.

  With this configuration, the fuel injection control device of the internal combustion engine performs in-cylinder injection when the piston is close to top dead center, so that the time until combustion is longer than in the latter half of the intake stroke. For this reason, the fuel injection control device of the internal combustion engine can secure a long time for diffusing the fuel and air in the cylinder, so that the homogeneity of the fuel and air in the cylinder is obtained immediately before the in-cylinder injection is performed in the compression stroke. By improving, it is possible to realize a reduction in PN discharged from the internal combustion engine by increasing the combustion speed.

  ADVANTAGE OF THE INVENTION According to this invention, in the internal combustion engine which can implement in-cylinder injection with a direct injection injector, the fuel injection control apparatus of the internal combustion engine which can reduce discharged | emitted PN than before can be provided.

It is the schematic which shows the fuel-injection control apparatus of the internal combustion engine which concerns on embodiment of this invention. It is the schematic which shows the fuel injection timing in the compression stroke and the intake stroke in the internal combustion engine which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the fuel-injection control apparatus of the internal combustion engine which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the configuration will be described.

  In the present embodiment, the internal combustion engine 1 performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while a piston 13 described later reciprocates twice in a cylinder 40 as a cylinder. A description will be given assuming that the engine is constituted by a four-cycle gasoline engine that performs ignition during the compression stroke and the expansion stroke.

  As shown in FIG. 1, the intake passage 2 of the internal combustion engine 1 is provided with a throttle valve 4 that opens and closes to adjust the amount of intake air taken into the combustion chamber 3. The throttle opening that is the opening of the throttle valve 4 is adjusted according to the accelerator opening that is the operation amount of the accelerator pedal 5 that is depressed by the driver of the vehicle.

  The internal combustion engine 1 in the present embodiment is a dual injection type including a port injection injector 6 and a direct injection injector 7. The port injector 6 injects fuel from the intake passage 2 toward the intake port 2 a communicating with the combustion chamber 3. The direct injection injector 7 is configured to inject fuel into the combustion chamber 3 formed by the cylinder 40 and the piston 13. The fuel stored in the fuel tank 8 is supplied to the port injector 6 and the direct injector 7.

  In the present embodiment, the internal combustion engine 1 includes a cylinder 40 and a direct injection injector 7 that can inject fuel into the cylinder 40. Furthermore, in the present embodiment, the internal combustion engine 1 includes an intake port 2a and a port injector 6 capable of injecting fuel toward the intake port 2a.

  The fuel in the fuel tank 8 is pumped up by the feed pump 9 and then supplied to the port injector 6 through the low-pressure fuel pipe 31. The pressure of the fuel in the low-pressure fuel pipe 31 is adjusted to the feed pressure through the drive control of the feed pump 9 and is not excessively raised by the pressure regulator 32 provided in the pipe 31. Further, a part of the fuel in the low-pressure fuel pipe 31 pumped up by the feed pump 9 is pressurized to a direct injection pressure higher than the feed pressure by the high-pressure fuel pump 10 and then directly injected through the high-pressure fuel pipe 33. 7 is supplied.

  In the internal combustion engine 1, an air-fuel mixture obtained by mixing fuel injected from the port injector 6 and the direct injector 7 and air flowing through the intake passage 2 is filled in the combustion chamber 3, and an ignition plug is supplied to the air-fuel mixture. 12 is ignited. When the air-fuel mixture is combusted by ignition, the piston 13 is moved by the combustion energy at that time, and the crankshaft 14 is rotated accordingly. On the other hand, the air-fuel mixture after combustion is sent to the exhaust passage 15 as exhaust gas.

  The combustion chamber 3 and the intake passage 2 are communicated or blocked by an intake valve 26. The intake valve 26 opens and closes with the rotation of the intake camshaft 25 that receives rotation transmission from the crankshaft 14. The combustion chamber 3 and the exhaust passage 15 are communicated or blocked by the exhaust valve 28. The exhaust valve 28 opens and closes with the rotation of the exhaust camshaft 27 that receives the rotation transmission from the crankshaft 14.

  The internal combustion engine 1 is provided with a variable valve timing mechanism 29 as a variable valve mechanism that varies the opening / closing characteristics of the intake valve 26. The variable valve timing mechanism 29 changes the valve timing of the intake valve 26 by changing the relative rotation phase of the intake camshaft 25 with respect to the crankshaft 14. By driving the variable valve timing mechanism 29, both the valve opening timing and the valve closing timing of the intake valve 26 are advanced or retarded while the valve opening period (operating angle) of the intake valve 26 is kept constant.

  Next, an electrical configuration of the fuel injection control device for the internal combustion engine of the present embodiment will be described.

  The fuel injection control device for the internal combustion engine includes an electronic control device 16 that controls various operations of the internal combustion engine 1. The electronic control unit 16 includes a central processing unit (CPU) as a central processing unit, a read only memory (ROM) that stores fixed data, and a random access memory (RAM) that temporarily stores data. An input interface, an output interface (both not shown), an EEPROM (Electrically Erasable and Programmable Read Only Memory) composed of a rewritable nonvolatile memory, and a communication means. In addition, the electronic control device 16 includes a split ratio determining unit 16a that calculates a split ratio of the split injection amounts Qd1 to Qd3 when split injection is performed from the direct injection injector 7.

  In the present embodiment, the fuel injection control device for the internal combustion engine includes the electronic control device 16 and controls the internal combustion engine 1. The electronic control device 16 is composed of an ECU (Electronic Control Unit) for supervising overall control of the internal combustion engine 1.

  For example, the ROM stores a control program, a map, and the like of the fuel injection control device for the internal combustion engine according to the present embodiment, and functions as a storage device. The CPU executes arithmetic processing based on a control program, a map, and a predetermined value stored in the ROM. Further, in the present embodiment, the fuel injection control program is periodically executed through an electronic control device 16 with an angle interruption for each predetermined crank angle.

  As a map stored in the ROM, for example, there is a map showing a relationship between a parameter corresponding to an intake air amount of the internal combustion engine 1, an engine speed, and an engine load. Further, as a map stored in the ROM, for example, there is a map showing the relationship between the engine load, the timing of the divided injection from the direct injection injector 7, and the injection amount.

The predetermined value stored in the ROM includes a low temperature range of cooling water for determining whether or not the internal combustion engine is in a low temperature state, for example, when the internal combustion engine 1 is started. As this low temperature range, the lower limit is 25 ° C. and the upper limit is 80 ° C. However, in the present embodiment, the lower limit of the low temperature range is 25 ° C. and the upper limit is 80 ° C., but it is of course not limited to this.

  The input port of the electronic control unit 16 includes an accelerator position sensor 17 for detecting the accelerator opening, a throttle position sensor 18 for detecting the throttle opening, and the amount of air passing through the intake passage 2, that is, the intake of the internal combustion engine 1. An air flow meter 19 that detects the amount of air and an intake pressure sensor (not shown) are connected. Among these sensors, for example, the accelerator position sensor 17, the air flow meter 19, and the intake pressure sensor function as an engine load sensor singly or in combination.

  In addition, a crank position sensor 20 that outputs a signal corresponding to the rotation of the crankshaft 14 and a signal corresponding to the rotational position of the intake camshaft 25 based on the rotation of the intake camshaft 25 are input to the input port of the electronic control unit 16. An output cam position sensor 21 is connected.

  Further, a water temperature sensor 22 for detecting the temperature of the cooling water of the internal combustion engine 1, a first pressure sensor 23 for detecting the feed pressure of the fuel in the low pressure fuel pipe 31, and a high pressure fuel are provided at the input port of the electronic control device 16. A second pressure sensor 24 that detects the direct injection pressure of the fuel in the pipe 33 and a knock sensor 30 that detects the occurrence of knocking in the internal combustion engine 1 are connected. The temperature of the cooling water of the internal combustion engine 1 detected by the water temperature sensor 22 constitutes the temperature of the internal combustion engine of the present invention.

  The output port of the electronic control unit 16 is connected to drive circuits of various devices such as the throttle valve 4, the port injection injector 6, the direct injection injector 7, the feed pump 9, the spark plug 12, and the valve timing variable mechanism 29. Yes.

  The electronic control unit 16 grasps the engine operation state such as the engine rotation speed and the engine load based on the signals input from various sensors, and the throttle valve 4, the port injection injector 6 and the direct injection based on the engine operation state of the vagina. Command signals are output to drive circuits of various devices such as the injector 7, feed pump 9, spark plug 12, and valve timing variable mechanism 29. Thus, various operation controls of the internal combustion engine 1 such as throttle opening control of the internal combustion engine 1, fuel injection control, ignition timing control, and valve timing control of the intake valve 26 are performed through the electronic control device 16.

  The engine speed is obtained based on a detection signal from the crank position sensor 20. The engine load is calculated from a parameter corresponding to the intake air amount of the internal combustion engine 1 and the engine speed. The parameters corresponding to the intake air amount include an actually measured value of the intake air amount of the internal combustion engine 1 obtained based on the detection signal from the air flow meter 19, a throttle opening degree obtained based on the detection signal from the throttle position sensor 18, and an accelerator. The accelerator operation amount etc. calculated | required based on the detection signal from the position sensor 17 can be raised.

  The fuel injection amount control performed as one of the fuel injection controls of the internal combustion engine 1 obtains the required fuel injection amount Qfin for the entire internal combustion engine 1 based on the engine operating state such as the engine speed and the engine load, and the required fuel injection. This is realized by performing fuel injection from the port injector 6 and the direct injector 7 so that the tatami mat Qfin is obtained.

  As fuel injection from the direct injection injector 7, for example, fuel injection in the compression stroke in the combustion cycle of the internal combustion engine 1, fuel injection in the latter half of the intake stroke, and fuel injection in the first half of the intake stroke can be selected. An example of the fuel injection period in each of these fuel injections is shown in FIG. In the first fuel injection period d1 shown in the figure, fuel injection is performed in the compression stroke. Further, in the second fuel injection period d2, fuel injection is performed in the latter half of the intake stroke, and in the third fuel injection period d3, fuel injection is performed in the first half of the intake stroke.

  With respect to the first fuel injection period d1, the second fuel injection period d2, and the third fuel injection period d3, the maximum determined based on the predetermined interval or the like because of a relationship that requires a predetermined interval therebetween. A value exists. The fuel injection from the direct injection injector 7 in the compression stroke, the fuel injection in the latter half of the intake stroke, and the fuel injection in the first half of the intake stroke are related to the realization of good engine operation for the following reasons.

  The fuel injection in the compression stroke has a feature that the injected fuel is easily collected around the spark plug 12 by an air flow in the cylinder 40, etc., so that the fuel in the cylinder 40 is favorably ignited and the combustion speed of the fuel is increased. Contributes to speed.

  In the fuel injection in the latter half of the intake stroke, when the moving speed of the piston 13 becomes slow and the generation of the airflow in the cylinder 40 due to the movement of the piston 13 becomes weak, the airflow in the cylinder 40 is strengthened by the injected fuel and good fuel combustion is performed. Contributes to

  In the fuel injection in the first half of the intake stroke, the injected fuel can be directly attached to the top of the piston 13, and therefore, the top of the piston 13 is cooled by the latent heat of vaporization of the fuel. This contributes to suppressing the occurrence of knocking.

  The fuel injection control device for an internal combustion engine according to the present embodiment controls fuel injection from a direct injection injector 7 capable of injecting fuel into a cylinder 40 of the internal combustion engine 1. The fuel injection control device for the internal combustion engine according to the present embodiment supplies fuel from the direct injection injector 7 during the compression stroke during the combustion cycle of the internal combustion engine 1 when the temperature of the internal combustion engine 1 is within a predetermined low temperature range. It comes to inject. In this case, in the fuel injection control device for the internal combustion engine of the present embodiment, the compression stroke is the latter half of the compression stroke.

  Further, in the fuel injection control device for an internal combustion engine of the present embodiment, the direct injection total injection amount Qd required for fuel injection into the cylinder 40 is larger than the fuel injection amount Qd1 required for injection in the compression stroke. The fuel is injected from the direct injection injector 7 in the intake stroke during the combustion cycle of the fuel injection amount obtained by subtracting the fuel injection amount Qd1 from the direct injection total injection amount Qd. In this case, in the fuel injection control device for the internal combustion engine of the present embodiment, the intake stroke is set to the first half of the intake stroke.

  In the fuel injection control device for an internal combustion engine according to the present embodiment, the internal combustion engine 1 includes an intake port 2 a and a port injection injector 6, and fuel injection from the port injection injector 6 to the internal combustion engine 1 is performed. The fuel is injected for the port injection amount Qp obtained by subtracting the direct injection total injection amount Qd from the required fuel injection amount Qfin. Furthermore, the fuel injection control device for the internal combustion engine of the present embodiment is configured to inject fuel only from the port injector 6 when the temperature of the internal combustion engine 1 is lower than the low temperature range.

  Next, the operation of the fuel injection control device for the internal combustion engine of the present embodiment will be described.

  A fuel injection control program for performing fuel injection by switching the split injection ratio in the direct injection injector 7 in accordance with the temperature of the internal combustion engine 1 will be described with reference to the flowchart of FIG. The fuel injection control program is periodically executed through an electronic control unit 16 with an angle interruption for each predetermined crank angle.

The electronic control unit 16 calculates the required fuel injection amount Qfin of the internal combustion engine 1 based on the engine operating state such as the engine rotation speed and the engine load (step S1). The electronic control unit 16 calculates the engine rotation speed based on the detection value of the crank position sensor 20 and calculates the engine load based on the detection value of the engine load sensor. Here, with expressed in 100% as the required fuel injection amount required fuel injection ratio _{R Qfin} the ratio of Qfin, ones ratios of the injection amount in the subsequent processing that represents the ratio of the required fuel injection ratio _{R Qfin} 100% And

  The electronic control unit 16 determines whether or not the temperature of the internal combustion engine 1 is equal to or lower than the upper limit of the low temperature range (step S2). Whether or not the temperature of the internal combustion engine 1 is equal to or lower than the upper limit of the low temperature range is determined by the electronic control unit 16 based on whether or not the coolant temperature is 80 ° C. or lower.

  When the electronic control unit 16 determines that the temperature of the internal combustion engine 1 is equal to or lower than the upper limit of the low temperature range (step S2; YES), the electronic control unit 16 has the temperature of the internal combustion engine 1 lower than the lower limit of the low temperature range. Whether or not (step S3). Whether or not the temperature of the internal combustion engine 1 is lower than the lower limit of the low temperature range is determined by the electronic control unit 16 based on whether or not the coolant temperature is lower than 25 ° C.

When the electronic control unit 16 determines that the temperature of the internal combustion engine 1 is less than the lower limit of the low temperature range (step S3; YES), the electronic control unit 16 is in the cryogenic range where the internal combustion engine 1 is lower than the low temperature range. Judge. For this reason, the electronic control unit 16 sets the port injection ratio R _Qp to 100% in order to inject fuel only from the port injector 6 without injecting fuel from the direct injection injector 7 (step S4). That is, the electronic control unit 16 sets the target port injection amount Qp to the same value as the required fuel injection amount Qfin.

  Then, the electronic control unit 16 performs port injection of fuel for the port injection amount Qp (= requested fuel injection amount Qfin) from the port injection injector 6 (step S5). Thereby, since the electronic control unit 16 stops the in-cylinder injection when the internal combustion engine 1 is in the cryogenic temperature range lower than the low temperature range, the generation of PN can be suppressed as much as possible.

If the electronic control unit 16 determines that the temperature of the internal combustion engine 1 is equal to or higher than the lower limit of the low temperature range (step S3; NO), the electronic control unit 16 determines that the internal combustion engine 1 is within the low temperature range. To do. Then, the electronic control unit 16 calculates a direct injection total injection ratio R _Qd for performing fuel injection from the direct injection injector 7 with respect to the required fuel injection amount Qfin (step S6). For example, the electronic control unit 16 may request deposit accumulation suppression, intake air amount detected by the air flow meter 19, A / F, fuel amount for suppressing the catalyst temperature to a predetermined temperature for catalyst protection, and the like. based on, sets the straight噴総injection ratio _{R Qd} with respect to the required fuel injection quantity Qfin.

Then, the electronic control unit 16 calculates a late-compression injection ratio R _Qd1 for performing fuel injection from the direct injection injector 7 in the latter half of the compression stroke with respect to the required fuel injection amount Qfin (step S7). The electronic control unit 16 determines the target fuel injection amount Qd1 in the latter stage of the compression stroke in the direct injection injector 7 based on the engine operation state such as the engine rotation speed and the engine load and the direct injection pressure, for example, at that time. A late-compression injection ratio R _Qd1 is calculated to obtain an optimum value for the state.

Further, the electronic control unit 16 determines whether or not the direct injection total injection ratio R _Qd is larger than the late compression injection ratio R _Qd1 (step S8). When the electronic control unit 16 determines that the direct injection total injection ratio R _Qd is larger than the late compression injection ratio R _Qd1 (step S8; YES), the electronic control unit 16 determines that the direct injection total injection amount Qd is the latter half of the compression stroke. It is determined that the fuel injection amount Qd1 will be larger. For this reason, the electronic control unit 16 directs the direct injection total injection so that the direct injection total injection amount Qd is subtracted by the fuel injection amount Qd1 in the latter half of the compression stroke from the direct injection injector 7 in the first intake stroke. _Subsequent compression late injection ratio R _Qd1 is subtracted from ratio R _Qd to set it as intake early injection ratio R _Qd3 (step S9).

Then, the electronic control unit 16 sets the port injection ratio R _Qp by subtracting the direct injection total injection ratio R _Qd from the required fuel injection ratio R _Qfin (= 100%) (step S10). The electronic control unit 16 performs fuel injection based on the late compression injection ratio R _Qd1 , the intake early injection ratio R _Qd3 , and the port injection ratio R _Qp (step S5). Specifically, the electronic control unit 16 injects the fuel for the fuel injection amount Qd1 calculated based on the late compression injection ratio R _Qd1 from the direct injection injector 7 in the latter half of the compression stroke, and _{sets the} intake early injection ratio R _Qd3 . The fuel corresponding to the fuel injection amount Qd3 calculated based on the direct injection injector 7 is injected into the cylinder in the first half of the intake stroke. Further, the electronic control unit 16 performs port injection of the fuel for the port injection amount Qp calculated based on the port injection ratio R _Qp from the port injection injector 6.

  As a result, the electronic control unit 16 injects fuel for the fuel injection amount Qd1 from the direct injection injector 7 in the latter half of the compression stroke, so that it becomes easy to collect the injected fuel around the spark plug 12 by the air flow in the cylinder 40 or the like. Therefore, the electronic control unit 16 can improve the ignition of the fuel in the cylinder 40 and increase the combustion speed of the fuel, so that the PN discharged from the internal combustion engine 1 can be reduced.

  In addition, even if the direct injection total injection amount Qd is set to be larger than the fuel injection amount Qd1 necessary for combustion in consideration of the deposit request, the electronic control unit 16 also includes the fuel injection for combustion in the direct injection total injection amount Qd. The fuel injection amount Qd3 exceeding the amount Qd1 can be injected into the cylinder in the first half of the intake stroke preceding the second half of the compression stroke. Therefore, the electronic control unit 16 can reduce deposit accumulation at the nozzle of the direct injection injector 7 without deteriorating the combustibility in the cylinder 40.

When the electronic control unit 16 determines that the direct injection total injection ratio R _Qd is not greater than the late compression injection ratio R _Qd1 (step S8; NO), the electronic control unit 16 determines that the direct injection total injection amount Qd is It is determined that the fuel injection amount Qd1 in the latter half of the compression stroke is not greater. For this reason, the electronic control unit 16 sets the late injection ratio R _Qd1 to the same value as the direct injection total injection ratio R _Qd in order to set the fuel injection quantity Qd1 in the latter half of the compression stroke to the same value as the direct injection total injection quantity Qd. Set (step S11).

Then, the electronic control unit 16 sets the port injection ratio R _Qp by subtracting the direct injection total injection ratio R _Qd from the required fuel injection ratio R _Qfin (= 100%) (step S10). The electronic control unit 16 performs fuel injection based on the late compression injection ratio R _Qd1 and the port injection ratio R _Qp (step S5). Specifically, the electronic control unit 16 injects fuel for the fuel injection amount Qd1 calculated based on the late compression injection ratio R _Qd1 from the direct injection injector 7 in the late compression stroke and based on the port injection ratio R _Qp . The port injection amount 6 of the calculated port injection amount Qp is port-injected from the port injection injector 6.

  As a result, the electronic control unit 16 injects fuel for the fuel injection amount Qd1 from the direct injection injector 7 in the latter half of the compression stroke, so that it becomes easy to collect the injected fuel around the spark plug 12 by the air flow in the cylinder 40 or the like. Therefore, the electronic control unit 16 can improve the ignition of the fuel in the cylinder 40 and increase the combustion speed of the fuel, so that the PN discharged from the internal combustion engine 1 can be reduced.

  Further, when the electronic control unit 16 determines that the temperature of the internal combustion engine 1 is less than the upper limit of the low temperature range (step S2; NO), the electronic control unit 16 emphasizes in-cylinder injection and fuel injection, for example. Divide port jets. That is, since the temperature of the internal combustion engine 1 is a normal temperature higher than the low temperature range, the electronic control unit 16 does not need to consider a special operation at a low temperature, and uses a known or new injection method that emphasizes fuel consumption. Can be adopted.

  In the present embodiment, the electronic control unit 16 calculates a direct injection total injection amount Qd for performing fuel injection from the direct injection injector 7 (step S12). For example, the electronic control unit 16 performs direct injection total injection based on the intake air amount detected by the air flow meter 19, the A / F, the fuel amount for suppressing the catalyst temperature to a predetermined temperature for catalyst protection, and the like. The quantity Qd is set.

  Then, the electronic control unit 16 calculates a divided injection amount Qd1 that is a target to be injected in the compression stroke (step S13). Specifically, the electronic control unit 16 sets the divided injection amount Qd1 in the compression stroke in the direct injection injector 7 based on the engine operation state such as the engine rotation speed and the engine load and the direct injection pressure to the engine operation state at that time. A first fuel injection period d1 for obtaining an optimum value is calculated. Then, the electronic control unit 16 calculates the target divided injection amount Qd1 by multiplying the first fuel injection period d1 by the direct injection pressure. Thereafter, the electronic control unit 16 determines whether or not the divided injection amount Qd1 is equal to or less than the direct injection total injection amount Qd. Here, if the electronic control unit 16 makes an affirmative determination, the electronic control unit 16 maintains the divided injection amount Qd1. If the electronic control unit 16 makes a negative determination, the electronic control unit 16 directly calculates the divided injection amount Qd1. Replace with the injection amount Qd.

  The electronic control unit 16 calculates the divided injection amount Qd2 in the latter half of the intake stroke (step S14). Specifically, the electronic control unit 16 calculates the remaining amount Q1, which is a value obtained by subtracting the divided injection amount Qd1 from the direct injection total injection amount Qd. The electronic control unit 16 calculates a second fuel injection period d2 for setting the divided injection amount Qd2 in the latter half of the intake stroke in the direct injection injector 7 to an optimum value for the engine operating state at that time. Then, the electronic control unit 16 calculates the target divided injection amount Qd2 by multiplying the second fuel injection period d2 by the direct injection pressure. Thereafter, the electronic control unit 16 determines whether or not the divided injection amount Qd2 is less than or equal to the remaining amount Q1. Here, if the electronic control unit 16 makes a positive determination, the electronic control unit 16 maintains the divided injection amount Qd2. If the electronic control unit 16 makes a negative determination, the electronic control unit 16 sets the divided injection amount Qd2 to the remaining amount Q1. Replace with.

  The electronic control unit 16 calculates the divided injection amount Qd3 in the first half of the intake stroke (step S15). Specifically, the electronic control unit 16 calculates a remaining amount Q2, which is a value obtained by subtracting the divided injection amount Qd2 from the remaining amount Q1. The electronic control unit 16 calculates a third fuel injection period d3 for setting the divided injection amount Qd3 in the first half of the intake stroke in the direct injection injector 7 to an optimum value for the engine operating state at that time. Then, the electronic control unit 16 calculates the target divided injection amount Qd3 by multiplying the third fuel injection period d3 by the direct injection pressure. Thereafter, the electronic control unit 16 determines whether or not the divided injection amount Qd3 is less than or equal to the remaining amount Q2. Here, if the electronic control unit 16 makes a positive determination, the electronic control unit 16 maintains the divided injection amount Qd3, and if the electronic control unit 16 makes a negative determination, the electronic control unit 16 sets the divided injection amount Qd3 to the remaining amount Q2. Replace with.

  Furthermore, the electronic control unit 16 calculates the port injection amount Qp (step S16). Specifically, the electronic control unit 16 calculates the remaining amount Q3 by subtracting the divided injection amounts Qd1 to Qd3 from the required fuel injection amount Qfin, and uses the remaining amount Q3 as the target for fuel injection in the port injector 6. Is set as the port injection amount Qp.

  Then, the electronic control unit 16 injects fuel for the divided injection amount Qd1 from the direct injection injector 7 in the latter half of the compression stroke, and in-cylinder injects fuel for the divided injection amount Qd3 in the first half of the intake stroke from the direct injection injector 7, The port injection amount Qp of fuel is port-injected from the port injection injector 6 (step S5).

  As described above, according to the fuel injection control device for an internal combustion engine according to the present embodiment, the electronic control device 16 uses the direct injection injector 7 in the latter half of the compression stroke when the temperature of the internal combustion engine 1 is within the low temperature range. Inject fuel from. As a result, the electronic control device 16 can easily collect the injected fuel around the spark plug 12 by the airflow in the cylinder 40 or the like as compared with the case where the fuel is injected in the intake stroke. Therefore, the electronic control unit 16 can improve the ignition of the fuel in the cylinder 40 and increase the combustion speed of the fuel, so that the PN discharged from the internal combustion engine 1 can be reduced.

  Further, according to the fuel injection control device for an internal combustion engine according to the present embodiment, the electronic control device 16 performs in-cylinder injection in the latter half of the compression stroke in which the piston 13 is close to top dead center in the compression stroke. Compared to the case of in-cylinder injection in the previous period, the time to combustion is shortened. For this reason, the electronic control unit 16 concentrates the injected fuel around the spark plug 12 at a high concentration and burns it, and the combustion speed of the fuel can be increased, so that the PN discharged from the internal combustion engine can be reduced. Further reduction can be achieved.

  Further, according to the fuel injection control device for an internal combustion engine according to the present embodiment, the electronic control device 16 has a direct fuel injection amount equal to or greater than the fuel injection amount Qd1 for combustion, for example, to prevent deposit accumulation. When requested as Qd, in-cylinder fuel is injected in the first half of the intake stroke by subtracting the fuel injection amount Qd1 from the direct injection total injection amount Qd. As a result, the electronic control unit 16 in-cylinder-injects the fuel injection amount Qd3 of the direct injection total injection amount Qd that exceeds the fuel injection amount Qd1 for combustion in the intake stroke prior to the compression stroke. The process proceeds to the compression stroke while maintaining the homogeneity of the fuel and air. Therefore, the electronic control unit 16 can appropriately maintain the homogeneity of the fuel and air in the cylinder 40 and the fuel injection amount Qd1 in the compression stroke while reducing the deposit accumulation at the nozzle of the direct injection injector 7, so that combustion is possible. A reduction in PN discharged from the internal combustion engine 1 can be realized by increasing the speed.

  Further, according to the fuel injection control device for an internal combustion engine according to the present embodiment, the electronic control device 16 performs in-cylinder injection in the first half of the intake stroke in which the piston 13 is close to top dead center in the intake stroke. Compared with the case of in-cylinder injection in the later stage, the time until combustion becomes longer. For this reason, the electronic control unit 16 can secure a long time for diffusing the fuel and air in the cylinder, so that the homogeneity of the fuel and air in the cylinder 40 is improved immediately before the in-cylinder injection is performed in the compression stroke. Thus, it is possible to reduce the PN discharged from the internal combustion engine 1 by increasing the combustion speed.

  Further, according to the fuel injection control device for an internal combustion engine according to the present embodiment, the internal combustion engine 1 includes the intake port 2 a and the port injection injector 6 in addition to the direct injection injector 7. For this reason, the fuel injection control device for the internal combustion engine is applied to the internal combustion engine 1 adopting a dual type fuel injection system in which the internal combustion engine 1 has two types of injectors, that is, a direct injection injector 7 and a port injection injector 6. Can do.

  Further, according to the fuel injection control device for an internal combustion engine according to the present embodiment, the electronic control device 16 injects fuel only from the port injector 6 when the temperature of the internal combustion engine 1 is lower than the low temperature range. For this reason, since the electronic control unit 16 stops the in-cylinder injection when the internal combustion engine 1 is in the extremely low temperature range lower than the low temperature range, the generation of PN can be suppressed as much as possible.

  Here, according to the in-cylinder injection, fuel is injected on the top of the piston 13 by fuel injection in the compression stroke, and an air-fuel mixture is filled around the spark plug 12 and burned, thereby obtaining a PN reduction effect. Can do. On the other hand, when the temperature of the internal combustion engine 1 is in a very low temperature state lower than the low temperature range, the fuel injected in the compression stroke and hitting the piston 13 may directly adhere to the piston 13 and become a PN generation source. is there. For this reason, according to the fuel injection control device for the internal combustion engine according to the present embodiment, the generation of PN can be suppressed as much as possible by adopting the port injection in the extremely low temperature state.

  In the fuel injection control device for the internal combustion engine of the present embodiment described above, the electronic control device 16 processes each injection amount as a ratio to the required fuel injection amount Qfin when the internal combustion engine 1 is in the low temperature range. Explained. However, the fuel injection control device for the internal combustion engine according to the present invention is not limited to this. For example, the electronic control device 16 does not particularly take into account the ratio of the internal combustion engine 1 and performs the processing without changing the injection amount. Also good.

  Further, in the fuel injection control device for the internal combustion engine of the present embodiment, the electronic control device 16 has been described for the case where in-cylinder injection is performed in the latter half of the compression stroke when the internal combustion engine 1 is in the low temperature range. However, the fuel injection control device for an internal combustion engine according to the present invention is not limited to this. For example, the electronic control device 16 performs in-cylinder injection in the first half of the compression stroke when the internal combustion engine 1 is in the low temperature range. Also good.

Moreover, in the fuel injection control device for the internal combustion engine of the present embodiment, the electronic control device 16 is in the case where the internal combustion engine 1 is in the low temperature range and the direct injection total injection ratio R _Qd is larger than the late compression injection ratio R _Qd1. In addition, the case where in-cylinder injection is performed in the first half of the intake stroke in addition to the compression stroke has been described. However, the fuel injection control device for the internal combustion engine according to the present invention is not limited to this. For example, the electronic control device 16 is configured such that the internal combustion engine 1 is in the low temperature range and the direct injection total injection ratio R _Qd is If the ratio R _{Qd1 is} greater, in-cylinder injection may be performed in the latter half of the intake stroke in addition to the compression stroke.

  Further, in the fuel injection control device for an internal combustion engine of the present embodiment, the case where the present invention is applied to the internal combustion engine 1 adopting the dual type fuel injection system having the direct injection injector 7 and the port injection injector 6 has been described. However, the fuel injection control device for an internal combustion engine according to the present invention is not limited to this. For example, the direct injection type internal combustion engine having only the direct injection injector 7 without the port injection injector 6 as the injection injector. You may make it apply.

  As described above, the fuel injection control device for an internal combustion engine according to the present invention has an effect that the discharged PN can be reduced as compared with the conventional one in an internal combustion engine capable of performing in-cylinder injection by a direct injection injector. It is useful for a fuel injection control device of an internal combustion engine.

  In the internal combustion engine 1 described above, operations in various operating states were confirmed.

Example 1
In the internal combustion engine 1 in the low temperature range, the electronic control unit 16 sets the direct injection total injection ratio R _Qd to 10% and sets the late compression injection ratio R _Qd1 to 10%.

As a result, since the direct injection total injection ratio R _Qd = the compression late injection ratio R _Qd1 , the electronic control unit 16 sets the compression late injection ratio R _Qd1 to 10% and _{sets the} port injection ratio R _Qp to R _Qfin −R _Qd. = 100-10 = 90%. As a result, the electronic control unit 16 in-cylinder injects 10% fuel and injects 90% fuel into the port in the latter half of the compression stroke.

As a result, compared with the case where the port injection ratio R _Qp is 100%, the PN emission can be reduced by 60%.

(Example 2)
In the internal combustion engine 1 in the low temperature range, the electronic control unit 16 sets the direct injection total injection ratio R _Qd to 20% and sets the late compression injection ratio R _Qd1 to 10%.

As a result, the direct injection total injection ratio R _Qd > the compression late injection ratio R _Qd1 , so the electronic control unit 16 maintains the compression late injection ratio R _Qd1 at 10%, and the intake early injection ratio R _{Qd3 becomes} R _Qd. −R _Qd1 = 20−10 = 10%, and the port injection ratio R _Qp was set to R _Qfin −R _Qd = 100−20 = 80%. The electronic control unit 16 injects 10% of the fuel into the cylinder in the latter half of the compression stroke, injects 10% of the fuel into the cylinder in the first half of the intake stroke, and injects 80% of the fuel into the port.

As a result, the amount of fuel cylinder injection during the compression stroke late from that could be maintained at 10% in the same manner as in Example 1, the port injection ratio R _Qp as compared with the case where the 100% discharge of PN 60 % Could be reduced.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2a Intake port 6 Port injection injector 7 Direct injection injector 16 Electronic control apparatus (fuel injection control apparatus of internal combustion engine)
40 cylinders
Qd Direct injection total injection amount Qd1 Division injection amount Qd2 in the compression stroke Division injection amount Qd3 in the latter half of the intake stroke Division fuel injection amount Qfin Port fuel injection amount in the first half of the intake stroke

Claims (6)

A fuel injection control device for an internal combustion engine that controls injection of the fuel from a direct injection injector capable of injecting fuel into a cylinder of the internal combustion engine,
A fuel injection control device for an internal combustion engine, wherein when the temperature of the internal combustion engine is within a predetermined low temperature range, the fuel is injected from the direct injection injector during a compression stroke during a combustion cycle of the internal combustion engine.   When the direct injection total injection amount required for fuel injection into the cylinder is larger than the fuel injection amount required for the injection in the compression stroke, the fuel injection amount is subtracted from the direct injection total injection amount. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein an amount of the fuel injection amount obtained in this way is injected from the direct injection injector during an intake stroke in the combustion cycle. The internal combustion engine includes an intake port and a port injector capable of injecting the fuel toward the intake port.
The port injection injector injects the fuel for a port injection amount obtained by subtracting the total direct injection amount from a required fuel injection amount required for fuel injection to the internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1 or 2.   The fuel injection control device for an internal combustion engine according to claim 3, wherein when the temperature of the internal combustion engine is lower than the low temperature range, the fuel is injected only from the port injector.   The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the compression stroke is a late stage of the compression stroke.   The fuel injection control device for an internal combustion engine according to claim 2, wherein the intake stroke is in the first half of the intake stroke.

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