JP2010053758A - Fuel injection quantity control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection quantity control device capable of achieving a target air-fuel ratio. <P>SOLUTION: The device controls a fuel injection quantity of two fuel injection valves INJ arranged in an intake port 19 for supplying fuel to one combustion chamber 25 of an engine 10, and corrects the fuel injection quantity based on a sticking fuel quantity sticking to the intake port 19, and separately calculates wet correction factors WET1 sand WET2 for its correction to the two fuel injection valves INJ. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection amount control device for an internal combustion engine, and more particularly to a fuel injection amount control device provided with a plurality of fuel injection valves in an intake passage.

2. Description of the Related Art As a fuel injection amount control device for an internal combustion engine, one that corrects the amount of fuel injected from a fuel injection valve that adheres to an intake passage is known (for example, Patent Document 1). The technique described in Patent Document 1 is a technique for correcting the amount of fuel adhering to the intake passage in the case of changing the fuel injection timing according to the operating state of the engine. The amount is corrected.
Japanese Patent Laid-Open No. 10-280994

  Although the technique described in Patent Document 1 has only one fuel injection valve, in recent years, an apparatus including two fuel injection valves has been proposed for the purpose of reducing exhaust gas and improving fuel consumption. When two fuel injection valves are provided, the amount of fuel adhering to the intake passage out of the fuel injected from each of the two fuel injection valves is not necessarily the same for both fuel injection valves. If the same correction is performed for both of the two fuel injection valves using the technique 1 as it is, the correction may not be appropriate, and as a result, the target air-fuel ratio may not be achieved.

  The present invention has been made based on this situation, and an object of the present invention is to provide a fuel injection amount control device capable of realizing a target air-fuel ratio.

  In order to achieve the object, the invention according to claim 1 is a fuel injection for controlling the fuel injection amount of a plurality of fuel injection valves provided in an intake passage for supplying fuel to each combustion chamber of an internal combustion engine. An amount control device, wherein at least one fuel injection amount among the fuel injection amounts of a plurality of fuel injection valves can be set to an amount different from other fuel injection amounts, and adheres to the intake passage Correction means for correcting the fuel injection amount based on the fuel amount is provided, and the correction means performs correction of the fuel injection amount separately for each fuel injection valve.

  As described above, in the present invention, since the fuel injection amount is corrected based on the adhered fuel amount separately for the plurality of fuel injection valves, the fuel injection amount can be corrected appropriately, and as a result, the target The air-fuel ratio can be realized.

  According to a second aspect of the present invention, the correction means uses the injection amount ratio indicating the fuel injection amount of each fuel injection valve with respect to the total amount of fuel injection injected from the plurality of fuel injection valves to determine the fuel injection amount based on the amount of adhered fuel The correction is performed separately for each fuel injection valve.

  When at least one fuel injection amount among the fuel injection amounts of the plurality of fuel injection valves can be set to an amount different from the other fuel injection amounts, correction based on the attached fuel amount using the injection amount ratio in this way It is preferable to carry out.

  According to a third aspect of the present invention, the timing of fuel injection from a plurality of fuel injection valves can be made different from each other, and the correction means uses the timing of fuel injection in addition to the injection amount ratio. It is characterized by performing.

  In the case where the fuel injection timings can be made different from each other, the fuel injection amount can be corrected more appropriately by performing the correction using the fuel injection timing as described above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of a fuel injection control apparatus according to an embodiment of the present invention. As shown in FIG. 1, in an engine 10 that is an internal combustion engine, an air cleaner 12 is provided at the most upstream portion of the intake pipe 11, and an air flow meter 13 for detecting the intake air amount is provided downstream of the air cleaner 12. Is provided.

  A throttle valve 14 whose opening degree is adjusted by a throttle actuator 15 such as a DC motor is provided on the downstream side of the air flow meter 13. The opening degree of the throttle valve 14 (throttle opening degree) is detected by a throttle opening degree sensor built in the throttle actuator 15.

  A surge tank 16 is provided on the downstream side of the throttle valve 14, and an intake pressure sensor 17 for detecting the pressure in the intake pipe 11 is provided in the surge tank 16. The surge tank 16 is connected to an intake manifold 18 for introducing air into each cylinder of the engine 10, and an intake port 19 is connected to the intake manifold 18. The intake port 19 is connected to each cylinder of the engine 10.

  A fuel injection valve INJ is attached to the intake port 19. In the present embodiment, as shown in FIG. 2, two fuel injection valves INJ, that is, a first fuel injection valve INJ1 and a second fuel injection valve INJ2 are provided. FIG. 2 is a schematic view taken along arrow A in FIG. As shown in FIG. 2, the intake port 19 has an end on the cylinder block 23 side that branches into two ports, a first intake port 19a and a second intake port 19b. At the tips of these two intake ports 19a and 19b, intake valves 21a and 21b are provided, respectively.

  The two fuel injection valves INJ1 and INJ2 are provided in the first intake port 19a and the second intake port 19b, respectively, and their arrangement directions are perpendicular to the longitudinal direction of the intake port 19.

  Returning to FIG. 1, a cylindrical cylinder inner wall surface 23a is formed on the cylinder block 23, and a crankcase 23b is formed below the cylinder inner wall surface 23a, and a piston 24 extends vertically in the cylinder inner wall surface 23a. It is slidably accommodated. An oil pan for storing engine oil is formed below the crankcase 23b. A combustion chamber 25 is defined by the cylinder inner wall surface 23 a, the upper end surface of the piston 24, and the inner peripheral surface of the cylinder head 26.

  When the intake valve 21 is opened during the operation of the engine 10, an air-fuel mixture of the fuel injected by the fuel injection valve INJ and the intake air is introduced into the combustion chamber 25. It is discharged to the exhaust pipe 27. The intake valve 21 and the exhaust valve 22 are provided with variable valve timing devices 28 and 29 for changing the valve timing of the valves 21 and 22, respectively.

  The variable valve timing devices 28 and 29 make the intake and exhaust camshaft phases variable with respect to the crankshaft, and the intake and exhaust valves 21 are changed by changing the valve timing accompanying the change of the camshaft phase. The overlap amount OL indicating the period during which both are open is adjusted.

  An ignition plug 30 is attached to the cylinder head 26 of the engine 10 for each cylinder, and a high voltage is applied to the ignition plug 30 at a target ignition timing through an ignition device (not shown) including an ignition coil or the like. The By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 30, and the air-fuel mixture introduced into the combustion chamber 25 is ignited and used for combustion.

  The exhaust pipe 27 is provided with a catalyst 31 such as a three-way catalyst for purifying CO, HC, NOx, etc. in the exhaust gas, and the air-fuel ratio of the air-fuel mixture with exhaust gas as a detection target upstream of the catalyst 31. An air-fuel ratio sensor (oxygen sensor or the like) 32 for detecting (or oxygen concentration) is provided. A cooling water temperature sensor 33 for detecting the cooling water temperature and a crank angle sensor 34 for outputting a rectangular crank angle signal for each predetermined crank angle of the engine are attached to the cylinder block 23 of the engine 10.

  Outputs of the various sensors described above are input to a control circuit (hereinafter referred to as ECU) 40 as an engine control device. The ECU 40 is mainly composed of a microcomputer including a CPU, ROM, RAM, backup RAM, and the like, and executes various control programs stored in the ROM, so that the fuel injection of the fuel injection valve INJ according to the engine operating state is performed. Control such as control of the amount, control of the ignition timing by the spark plug 30, control of the valve timing of the intake valve 21 is executed.

  FIG. 3 is a flowchart showing a fuel injection control process executed by the ECU 40. Note that the process shown in FIG. 3 is not limited to when the engine 10 is in a cold state, but is always executed at a predetermined cycle while the engine 10 is being driven.

First, in step S1, the basic fuel injection time Tp is calculated. This basic fuel injection time Tp is calculated by Equation 1 where K is a constant determined by the characteristics of the fuel injection valve INJ, Q is the intake air amount, and N is the engine speed. The intake air amount Q is determined based on a signal from the air flow meter 13, and the engine rotation speed N is determined based on a signal from the crank angle sensor 34.
(Formula 1) Tp = K × Q / N

In the subsequent step S2, the invalid injection time Ts is calculated. This invalid injection time Ts is calculated by the following equation 2. In Equation 2, VB is a battery voltage, Tsi is an invalid injection time set at a predetermined battery voltage, and ΔTs is a preset constant.
(Formula 2) Ts = Tsi + ΔTs × VB

Step S3 is processing as correction means in claims, and performs wet correction coefficients WET1 and WET2 separately for the fuel injection valves INJ1 and INJ2. The process in step S3 will be described later with reference to FIG. In step S4, the instruction time Ti1 to the fuel injection valve INJ1 is calculated using the calculation results of steps S1 to S3 and expression 3, and the fuel injection valve is calculated using the calculation results of steps S1 to S3 and expression 4. The instruction time Ti2 for INJ2 is calculated.
(Formula 3) Ti1 = Tp × WET1 × Ts
(Formula 4) Ti2 = Tp × WET2 × Ts

  In step S5, command pulses whose time widths are the instruction times Ti1 and Ti2 calculated in step S4 are output to the fuel injectors INJ1 and INJ2. As a result, fuel is injected into the intake port 19.

  Next, the calculation process of the wet correction coefficient WET will be described in detail with reference to FIG. First, in step S31, the injection amount indicating the ratio of the injection amount of the first fuel injection valve INJ1 to the total injection amount (the total amount of the injection amount of the first fuel injection valve INJ1 and the injection amount of the second fuel injection valve INJ2). The ratio INJRATIO1 and the injection amount ratio INJRATIO2 indicating the ratio of the injection amount of the second fuel injection valve INJ2 to the total injection amount are read. These injection amount ratios INJRATIO are determined using an injection amount ratio determination map stored in advance after determining the engine speed N and the engine load ELOAD. It should be noted that the injection amount ratio determination map shows that the injection amount ratio INJRATIO approaches 0.5 (equal to the left and right) as the engine rotational speed N increases and the engine load ELOAD increases, and the engine load ELOAD is small. Either one of the injection amount ratios INJRATIO increases. As the engine load ELOAD, specifically, the intake air amount Q that can be detected by the air flow meter 13 is used, but the pressure in the surge tank 16, that is, the detected value of the intake pressure sensor 17 may be used.

  In step S32, the injection timing INJTIMING is read. This injection timing INJTIMING is also determined by using the engine rotation speed N and the engine load ELOAD, and using an injection timing determination map stored in advance.

  In step 33, an engine load change amount ΔELOAD is calculated. This engine load change amount ΔELOAD is calculated by subtracting the previous engine load ELOAD from the current engine load ELOAD.

  In step S34, a basic wet amount WETBASE is calculated. The basic wet amount WETBASE is determined from a basic wet amount determination map stored in advance using the engine load change amount ΔELOAD calculated in step S33 and the water temperature detected by the cooling water temperature sensor 33. FIG. 5 is a diagram showing this basic wet amount determination map. As shown in FIG. 5, in the basic wet amount determination map, the basic wet amount WETBASE increases as the water temperature decreases and as the engine load change amount ΔELOAD increases. The basic wet amount WETBASE determined here indicates the amount of adhering fuel when it is assumed that all fuel is injected by one fuel injection valve INJ.

  In step S35, it is determined from the injection amount ratio INJRATIO read in step S31 whether twin injection is being performed. If twin injection is being performed, the process proceeds to step S37, and if twin injection is not being performed, the process proceeds to step S36.

  In step S36, it is determined whether or not the injection is only for the first fuel injection valve INJ1. If it is the injection of only the first fuel injection valve INJ1, the process proceeds to step S39. Otherwise, that is, if it is the injection of only the second fuel injection valve INJ2, the process proceeds to step S40.

  In step S39, the wet correction coefficient WET1 is set to the basic wet amount WETBASE calculated in step S34, while the wet correction coefficient WET2 is determined to be zero. Conversely, in step S40, the wet correction coefficient WET1 is determined to be zero, while the wet correction coefficient WET2 is set to the basic wet amount WETBASE calculated in step S34.

  In step S37, which is executed when twin injection is being performed, correction factors KINJWET1 and 2 for correcting the basic wet amount WETBASE are determined. The correction factors KINJWET 1 and 2 are determined from the correction factor determination map shown in FIG. 6 using the injection amount ratio INJRATION read in step S31 and the injection timing INJTIMING read in step 32. In this correction factor determination map, the correction factor increases as the injection amount ratio INJRATIO increases, and the correction factor increases as the injection timing is retarded.

  In step S38, the wet correction coefficient WET1 is calculated by multiplying the basic wet amount WETBASE by the correction factor KINJWET1, and the wet correction coefficient WET2 is calculated by multiplying the basic wet amount WETBASE by the correction factor KINJWET2.

  When the wet correction coefficients WET1 and WET2 are determined by executing any one of steps S38 to S40, the processing of FIG. 4 is terminated and the instruction times Ti1 and 2 are calculated in step S4 of FIG. Become.

  As described above, according to the embodiment described above, the fuel injection amount is corrected based on the adhered fuel amount separately for the two fuel injection valves INJ1 and INJ2, so that the fuel injection amount can be corrected appropriately. As a result, the target air-fuel ratio can be realized.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following embodiment is also contained in the technical scope of this invention, and also the summary other than the following is also included. Various modifications can be made without departing from the scope.

  For example, in the above-described embodiment, the arrangement direction of the two fuel injection valves INJ1 and INJ2 is perpendicular to the longitudinal direction of the intake port 19. However, the present invention is not limited to this, and the two fuel injection valves INJ1 and 2 are connected to the intake passage. It may be arranged along the longitudinal direction.

  In the above-described embodiment, the injection amount ratio INJRATIO and the injection timing INJTIMING are used as parameters for determining the correction factors KINJWET1 and 2 for correcting the basic wet amount WETBASE. However, only one of them is used. The correction factors KINJWET1 and 2 may be determined. In particular, as in the above-described embodiment, when the arrangement direction of the two fuel injection valves INJ1, 2 is perpendicular to the longitudinal direction of the intake passage, fuel is injected at the same fuel injection timing INJTIMING. Therefore, even if the correction rate KINJWET is determined only from the injection amount ratio INJRATIO without using the injection timing INJTIMING, the accuracy reduction of the wet correction coefficient WET is small.

  In the above-described embodiment, while the engine 10 is being driven, the basic fuel injection time Tp is always corrected using the wet correction coefficient WET. However, the amount of fuel adhering to the intake path is particularly high until the engine 10 is warmed up. Therefore, the correction using the wet correction coefficient WET may be limited until the engine 10 is warmed up.

  In the above-described embodiment, the number of fuel injection valves INJ is two, but may be three or more.

1 is a diagram illustrating an overall configuration of a fuel injection control device according to an embodiment of the present invention. FIG. 2 is a schematic view taken along arrow A in FIG. 1. It is a flowchart which shows the fuel-injection control process which ECU40 performs. It is a figure explaining the calculation process of the wet correction coefficient WET in detail. It is a figure which shows a basic wet amount determination map. It is a figure which shows a correction factor determination map.

Explanation of symbols

10: engine (internal combustion engine), 11: intake pipe, 18: intake manifold, 19: intake port, 19a: first intake port, 19b: second intake port, 25: combustion chamber, INJ: fuel injection valve

Claims (3)

A fuel injection amount control device for controlling the fuel injection amount of a plurality of fuel injection valves provided in an intake passage for supplying fuel to each combustion chamber of an internal combustion engine,
It is possible to set at least one fuel injection amount among the fuel injection amounts of the plurality of fuel injection valves to an amount different from other fuel injection amounts, and
Correction means for correcting the fuel injection amount based on the amount of fuel adhering to the intake passage;
The fuel injection amount control device is characterized in that the correction means corrects the fuel injection amount separately for each fuel injection valve. In claim 1,
The correction means corrects the fuel injection amount based on the adhered fuel amount by using the injection amount ratio indicating the fuel injection amount of each fuel injection valve with respect to the total amount of fuel injection injected from the plurality of fuel injection valves. A fuel injection amount control device, which is performed separately for a valve. In claim 2,
The timing of fuel injection from a plurality of fuel injection valves can be made different from each other,
The fuel injection amount control apparatus according to claim 1, wherein the correction means performs the correction using a fuel injection timing in addition to the injection amount ratio.

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