JP3956455B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for suitably controlling a fuel injection amount during a period from the beginning of engine startup to a complete explosion.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a technique for setting a fuel injection amount by an injector in accordance with an engine temperature (cooling water temperature) when starting an internal combustion engine is known. This is to correct the fuel injection amount to the increase side, for example, at the time of low temperature start of the engine. Such fuel increase correction is mainly performed to compensate for the adhesion of fuel to the wall surface and the lack of vaporization.
[0003]
Similarly, a technique for correcting the fuel injection amount in accordance with the engine speed is also known in order to inject and supply a required fuel amount in accordance with the engine speed at that time when the internal combustion engine is started.
[0004]
[Problems to be solved by the invention]
However, the above-mentioned conventional existing technique invites the following problems. That is, at the time of starting the engine, there is a fact that the engine speed after the first explosion does not increase unambiguously due to the influence of engine friction (such as friction of the piston sliding portion) corresponding to the engine temperature. For example, the friction is large at a low temperature start and the rotation speed increase after the first explosion is relatively slow, whereas the friction is small at a high temperature restart and the rotation speed increase after the first explosion is relatively fast. Incidentally, it is considered that the friction is substantially proportional to factors such as kinematic viscosity of engine oil.
[0005]
In such a case, when the engine friction is different, the degree of increase in the engine speed is different, and the actual required fuel amount for obtaining the complete explosion torque is also changed. Therefore, with the existing technology that performs unambiguous correction without taking engine friction into account when correcting the rotational speed of the fuel injection amount, it has been impossible to perform accurate fuel injection control. Further, since the fuel injection amount proportional to the engine temperature is set in any rotational range when the rotational speed is corrected, the fuel injection control that follows the actual rotational fluctuation cannot be performed.
[0006]
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a fuel injection control device for an internal combustion engine capable of accurately controlling the fuel injection amount at the time of starting the engine. It is.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to a rotational speed detecting means for detecting an engine rotational speed, and a starting fuel amount in a process from the initial explosion to the complete explosion of the internal combustion engine. In the process of calculating the starting fuel amount to be calculated, and in the same process from the first explosion to the complete explosion, the first fuel amount is corrected to the increase side as the engine speed decreases. In correcting the fuel amount by the correcting means and the first correcting means, As the degree of increase in engine speed decreases, the correction amount calculated from the engine speed is increased, Depending on the degree of increase in engine speed Change the amount of increase or decrease of the correction amount And a second correction means.
[0008]
In short, during the period from the initial explosion to the complete explosion of the internal combustion engine, the calculation and correction of the starting fuel amount are generally performed according to the engine temperature and the engine speed. In such a case, if the engine friction is different, the degree of increase in the engine speed immediately after the first explosion is different, and the required fuel amount for obtaining a desired output torque (complete explosion torque) required for the complete explosion also changes. Therefore, in the present invention, in the process from the initial explosion to the complete explosion, the lower the engine speed, the more the starting fuel amount is corrected, and the fuel amount is adjusted according to the degree of increase in the engine speed at that time. It was decided to increase or decrease. Thus, for example, even when the engine friction becomes large at the time of starting the engine at an extremely low temperature, the required fuel amount corresponding to the friction can be injected and supplied, and a desired output torque can always be obtained. That is, when correcting the number of revolutions of the fuel injection amount, an originally required output torque is always obtained, unlike a conventional device that simply sets a fuel injection amount proportional to the engine temperature (engine water temperature). As a result, the fuel injection amount at the time of starting the engine can be controlled with high accuracy.
[0009]
Incidentally, in this specification, “initial explosion” means a state in which combustion in a cylinder starts after initial rotation is applied by a starter motor or the like, and “complete explosion” means that the internal combustion engine rotates by itself. It means a state that can be maintained.
[0010]
According to a second aspect of the present invention, the second correcting means reduces the difference in the amount of increase / decrease in the correction amount due to the difference in the degree of increase in the rotational speed as the internal combustion engine is about to complete explosion. That is, immediately before the internal combustion engine reaches a complete explosion (complete explosion speed), since the engine is close to a state where it can maintain its rotation by itself, the correction according to the difference in the degree of increase in the rotational speed (the second correction means). Correction) is no longer necessary. Therefore, near the completion of the complete explosion, the difference in the correction amount of the starting fuel amount is reduced regardless of the degree of engine friction at the beginning of starting.
[0011]
According to a third aspect of the present invention, the second correction means gradually increases the difference in the amount of increase / decrease in the correction amount due to the difference in the degree of increase in the rotational speed with the passage of time from the initial explosion of the internal combustion engine. Thereafter, the difference in the amount of increase / decrease in the correction amount due to the difference in the degree of increase in the rotational speed is gradually reduced as the explosion is nearing completion. According to this configuration, it is possible to appropriately control the fuel amount until the complete explosion state is reached at the time of engine start, in which the degree of increase in the rotational speed is different each time.
[0012]
According to a fourth aspect of the present invention, the second correction means increases the correction amount by the first correction means, assuming that the degree of increase in the rotational speed is smaller as the engine temperature is lower. That is, if the engine temperature (for example, engine water temperature) is low and the influence of friction is large, the degree of increase in engine speed is small, and the amount of fuel required until a complete explosion state is increased. Therefore, if the starting fuel amount is increased / decreased according to the engine temperature, the fuel injection amount can be substantially controlled according to the difference in the degree of increase in the rotational speed, and the output torque corresponding to the friction can be output from the internal combustion engine. It can be taken out.
[0013]
Moreover, even if the present invention is embodied as in the following claims 5 and 6, the desired object can be achieved. That is,
In the invention according to claim 5, the first correction means uses the number of combustion cycles from the start of the engine instead of the engine speed, and the smaller the number of cycles, the more the calculated starting fuel amount. Correct to the increase side.
In the invention according to claim 6, the first correction means uses the valve opening time of the intake valve instead of the engine speed, and the longer the valve opening time of the valve, the more the calculated starting fuel amount. Is corrected to the increase side.
[0016]
Claim 7 In the invention described in the above, a complete explosion determination means for determining whether or not the internal combustion engine has reached a complete explosion, and a complete explosion determination value setting means for setting a complete explosion determination value by the complete explosion determination means in accordance with the engine temperature. And further comprising. That is, the rotational speed at which the internal combustion engine can maintain its rotation by itself varies depending on the engine temperature. Specifically, the lower the engine temperature, the higher the complete explosion speed. Under such circumstances, according to the above-described configuration, proper fuel injection amount control can be continued in the period until the complete explosion actually occurs.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The fuel injection control device according to the present embodiment is a system that controls the fuel injection amount to the engine by an electronic control device (hereinafter referred to as ECU) mainly composed of a well-known microcomputer. The present invention relates to an apparatus for appropriately controlling the amount. First, with reference to FIG. 1, the structure of the apparatus of this Embodiment and the internal combustion engine to which the apparatus is applied will be described.
[0018]
The engine 10 is a four-cylinder spark ignition type internal combustion engine having four cylinders of first to fourth (# 1 to # 4), and the combustion order is # 1 → # 3 → # 4 → # 2. Yes. Each cylinder is provided with an injector 1 as shown. Fuel pumped from a fuel supply system (not shown) is distributed and supplied to the injectors 1 of the respective cylinders through the delivery pipe 2. When the injector 1 is driven to open for a time corresponding to the fuel injection amount commanded by the ECU 30, fuel is injected and supplied to the corresponding cylinders.
[0019]
On the other hand, the fuel injected and supplied by the injector 1 is mixed with the air sucked through the air cleaner 12, the throttle valve 14 and the surge tank 15 provided in the intake pipe 11 of the engine 10. This air-fuel mixture is introduced into the combustion chamber 18 in the cylinder 17 via the intake valve 16.
[0020]
Here, the throttle valve 14 is a valve that adjusts the amount of air taken into the intake pipe 11 and mixed with the injected fuel, for example, in conjunction with an accelerator pedal (not shown) of the vehicle. The surge tank 15 is disposed to suppress pulsation of air sucked through the throttle valve 14.
[0021]
The air-fuel mixture introduced into the combustion chamber 18 in the cylinder 17 is compressed therein and is ignited and explodes when an ignition spark is emitted from the spark plug 19. The engine 10 obtains rotational torque by this explosion. Further, the burned gas is discharged to the exhaust pipe 21 through the exhaust valve 20 as exhaust gas. Note that the spark plug 19 generates the ignition spark by application of a high voltage boosted by the ignition coil 22 and distributed to each cylinder by the distributor 23.
[0022]
The starter motor 28 applies initial rotation to the engine 10 at the time of start-up, and is driven to rotate by receiving power supply from the battery 50 in accordance with an ON operation of the starter switch 40.
[0023]
On the other hand, the above apparatus detects the operating state of the engine 10 through various sensors as described below.
An air flow meter 13 is disposed in the intake pipe 11, and the air flow meter 13 measures the amount of air (intake amount) taken into the intake pipe 11. The distributor 23 is provided with a rotation speed sensor 24 that detects the rotation speed and rotation angle of the engine 10. Here, the rotation speed sensor 24 outputs a pulsed rotation angle signal (NE pulse) every 30 ° CA. Further, a water temperature sensor 26 is disposed in the cylinder 17 (water jacket) of the engine 10, and the sensor 26 detects the temperature of the engine cooling water. The outputs of these sensors are all taken into the ECU 30.
[0024]
The ECU 30 detects control parameters such as the intake air amount, the engine speed NE, and the water temperature Tw based on the detection outputs from the various sensors 13, 24, and 26, and based on these data, the fuel injection amount ( Time) and ignition timing. And the drive of the said injector 1 and the ignition coil 22 is controlled based on the said calculation result.
[0025]
The ECU 30 also receives operation information (ON / OFF) of the starter switch 40. The ECU 30 determines whether the engine 10 has been started based on the operation information of the starter switch 40. The ECU 30 receives power from the battery 50 and executes various controls including fuel injection control described later with the battery voltage VB.
[0026]
Next, the operation of the fuel injection control device configured as described above will be described. FIG. 2 is a flowchart showing a fuel injection control routine, which is executed by the ECU 30 every NE pulse, that is, every 30 ° CA.
[0027]
When the routine of FIG. 2 starts, the ECU 30 first determines in step 101 whether or not the complete explosion flag XST is “0”. The complete explosion flag XST indicates whether or not the engine 10 after the start has reached a complete explosion, and XST = 0 indicates that it is before the complete explosion, and XST = 1 indicates that it is after the complete explosion. . Incidentally, the flag is initialized to “0” when the ECU 30 is initially turned on.
[0028]
If XST = 0, the ECU 30 proceeds to step 102 and reads various information required for fuel injection control at the time of engine start. That is, the engine rotational speed NE detected by the rotational speed sensor 24, the water temperature Tw detected by the water temperature sensor 26, and the battery voltage VB are read.
[0029]
Thereafter, the ECU 30 searches the map for the complete explosion determination rotational speed STBNE in step 103. Specifically, in accordance with the relationship of FIG. 3, the complete explosion determination rotational speed STBNE corresponding to the water temperature Tw at that time is set. According to FIG. 3, STBNE = 800 rpm is set when Tw <−20 ° C., STBNE = 600 rpm is set when Tw = −20 to 0 ° C., and STBNE = 400 rpm is set when Tw> 0 ° C.
[0030]
Thereafter, in step 104, the ECU 30 compares the engine rotational speed NE with the complete explosion determination rotational speed STBNE. If NE <STBNE, the ECU 30 regards it as being before the complete explosion, makes a negative determination in step 104, and proceeds to step 105. In step 105, the ECU 30 searches for a map of the starting fuel amount TAUST using, for example, the relationship shown in FIG. According to FIG. 4, a larger value is set as the starting fuel amount TAUST as the water temperature Tw is lower. In the present embodiment, the starting fuel amount TAUST is handled as a numerical value obtained by converting the required fuel amount into time (unit: [msec]).
[0031]
Further, the ECU 30 searches the map for the rotation correction coefficient KNEST using the relationship shown in FIG. According to FIG. 5, the rotation correction coefficient KNEST is calculated according to the water temperature Tw and the engine speed NE at that time.
[0032]
Here, FIG. 5 will be described in detail. As the engine speed NE is lower in the rotation range before the complete explosion (for example, NE ≦ 800 rpm), a larger value is set as the rotation correction coefficient KNEST, and the KNEST value is set. A plurality of characteristic lines are set according to the water temperature Tw. In the present embodiment, the KNEST value is set in the range of “1 to 4”. Characteristic lines L1, L2, and L3 in the figure correspond to Tw = 0 ° C. or higher, Tw = −20 to 0 ° C., and Tw = −40 to −20 ° C., respectively. These characteristic lines L1 to L3 correspond to the difference in engine friction depending on the water temperature Tw, and the lower the water temperature Tw, the larger the friction and the larger the KNEST value. According to FIG. 5, even when the NE increase degree at the start of the engine is not constant due to the difference in engine friction, that is, for example, when the NE increase degree at the first explosion is relatively small at extremely low temperatures, for example. The fuel amount can be corrected according to the degree of NE increase.
[0033]
In step 107, the ECU 30 calculates the fuel injection amount TAU [msec] using the following equation (1), and then ends this routine once.
TAU = TAUST / KNEST / Kst (1)
Here, “Kst” in Expression (1) is a correction coefficient related to parameters other than the water temperature Tw and the engine speed NE, and corresponds to, for example, a correction coefficient based on the battery voltage VB.
[0034]
On the other hand, if NE ≧ STBNE, the ECU 30 regards that a complete explosion has been reached, and makes an affirmative determination in step 104 and proceeds to step 108. The ECU 30 sets “1” to the complete explosion flag XST in step 108 and calculates the TAU value after the start in step 109. At this time, in general, the basic injection amount is calculated according to the engine speed NE and the engine load (intake amount), and air-fuel ratio correction is performed on the basic injection amount to calculate the TAU value. .
[0035]
After the complete explosion flag XST is set to “1”, the determination at step 101 is negative every time, and the ECU 30 proceeds directly from step 101 to step 109 to calculate the TAU value after starting (normal fuel injection control is performed). carry out).
[0036]
FIG. 6 is a time chart showing the above control operation more specifically.
FIG. 6 shows the fuel injection operation at the start of the engine 10 when the engine 10 is cold started (when Tw = −40 to −20 ° C.). Note that the crank angle counter in the figure is a counter that is counted up every NE pulse (every 30 ° CA), and every combustion of each cylinder of # 1 to # 4 is completed every 720 ° CA (1 It is cleared to “0” every cycle). The counter is counted within the range of “0 to 24”. However, the counting operation is performed in the TAU calculation routine of FIG. 2, but the illustration thereof is omitted in FIG.
[0037]
The injection signal to each cylinder is output from the ECU 30 in the order of # 1 → # 3 → # 4 → # 2. At the beginning of engine startup, the complete explosion flag XST is initialized to “0”. At the time of cranking by the starter motor 28, the engine speed NE is in the minute rotation range, and according to the routine of FIG. 2, the starting fuel amount TAUST and the rotation correction coefficient KNEST are calculated and the TAUST value and the KNEST value are calculated. The fuel injection amount TAU is set based on (steps 105 to 107 in FIG. 2). Note that at the beginning of the engine start, the rotation correction coefficient KNEST is held at the maximum value (= 4) (see FIG. 5).
[0038]
When the first explosion is reached at time t1 in the figure, the engine speed NE starts to increase, and the rotation correction coefficient KNEST decreases in response to the increase in NE. That is, the rotation correction coefficient KNEST starts to decrease in accordance with the relationship shown in FIG. 5, and the fuel injection amount TAU is gradually decreased as compared with the start. At this time, since Tw = −40 to −20 ° C., the KNEST value is set based on the characteristic line L3 in FIG.
[0039]
When the engine speed NE reaches the complete explosion speed STBNE (in this case, 800 rpm), the complete explosion flag XST is set to “1”. After the flag is set, normal fuel injection control is performed instead of the fuel injection control at the start (step 109 in FIG. 2).
[0040]
On the other hand, when the engine is started with Tw ≧ 0 ° C., the engine friction becomes relatively small. Therefore, as indicated by a two-dot chain line in FIG. 6, the degree of increase in the engine speed NE immediately after the first explosion (after time t1) is greater than when Tw = −40 to −20 ° C. (solid line). In this case, according to the relationship of FIG. 5, the rotation correction coefficient KNEST is set based on the characteristic line L1, and the KNEST value is determined based on the rotation correction coefficient KNEST at Tw = −40 to −20 ° C. (based on the characteristic line L3). Value). That is, when Tw ≧ 0 ° C., the NE increase degree after the first explosion is relatively large, so the correction range for correcting the increase in the fuel injection amount TAU is set to be small.
[0041]
In the present embodiment, step 105 in FIG. 2 corresponds to “starting fuel amount calculating means”, and steps 106 and 107 correspond to “fuel amount correcting means”. In the relationship of FIG. 5 used in step 106 of FIG. 2, the process of setting the KNEST value according to the engine speed NE is referred to as “first correction means”, and the characteristic lines L1 to L3 for each water temperature Tw. Accordingly, the process of setting the same KNEST value corresponds to “second correction means”. Further, step 103 in FIG. 2 corresponds to “complete explosion determination value setting means”, and step 104 corresponds to “complete explosion determination value means”.
[0042]
According to the embodiment described in detail above, the following effects can be obtained.
(A) In the present embodiment, in the process from the initial explosion to the complete explosion of the engine 10, the starting fuel amount TAUST is calculated according to the water temperature Tw, and the starting fuel becomes lower as the engine speed NE is lower. The amount TAUST was corrected to the increase side. Further, in the fuel amount correction, the correction amount (rotation correction coefficient KNEST) is increased or decreased according to the degree of increase in the engine speed NE at that time.
[0043]
In short, if the engine friction is different in the period from the first explosion to the complete explosion of the engine 10, the NE increase degree immediately after the first explosion differs, and the required fuel amount for obtaining a desired complete explosion torque also changes. Therefore, in the process from the first explosion to the complete explosion, the fuel amount TAUST at the start is corrected to the increase side as the NE becomes lower, and the rotation correction coefficient KNEST of the fuel amount TAUST is changed according to the difference in the NE increase degree at that time. It was decided to increase or decrease. Specifically, the KNEST value is increased or decreased according to the water temperature Tw.
[0044]
As a result, even if the NE increase degree at the time of starting the engine fluctuates, that is, for example, when the engine friction becomes large at the time of starting the engine at a very low temperature, the required fuel amount corresponding to the friction can be injected and supplied. A desired output torque is always obtained. That is, when correcting the rotational speed of the fuel injection amount, unlike the conventional device that simply sets the fuel injection amount proportional to the engine water temperature, the output torque that is originally necessary can always be obtained. As a result, the fuel injection amount at the time of starting the engine can be controlled with high accuracy.
[0045]
(B) As shown in the relationship of FIG. 5, the width between the characteristic lines L1 to L3 (corresponding to “difference in increase / decrease in correction amount”) is gradually increased as the engine speed of the engine 10 increases from the first explosion. The width between the characteristic lines L <b> 1 to L <b> 3 was gradually decreased as the engine 10 was almost completely exhausted. That is, immediately before the complete explosion of the engine 10, since the engine 10 is close to a state in which the engine 10 can maintain its rotation, correction according to the difference in NE increase (use of the characteristic lines L1 to L3 in FIG. 5) is much. No longer needed. Therefore, the degree of correction of the starting fuel amount TAUST is reduced near the end of the complete explosion. According to this configuration, it is possible to appropriately control the fuel amount until the complete explosion state is reached at the time of starting the engine in which the NE increase degree is different each time.
[0046]
(C) Further, the complete explosion determination rotational speed STBNE is variably set according to the water temperature Tw, and it is determined whether or not the engine 10 has reached a complete explosion according to the complete explosion determination rotational speed STBNE. In this case, even if the rotational speed at which the engine 10 can maintain the rotation by itself varies depending on the water temperature Tw (engine temperature), the proper fuel injection amount control can be continued in the period until the complete explosion actually occurs.
[0047]
(D) Since the fuel injection control at the time of starting the engine can be performed properly, the effect of reducing the emission emission amount at the time of starting is also obtained.
[0048]
The embodiment of the present invention can be realized in the following form in addition to the above.
(Another form 1)
At the time of engine start, if the period in which combustion of all cylinders # 1 to # 4 is completed, that is, the period of 720 ° CA is set to “one cycle”, the required fuel amount of each cylinder tends to be determined for each cycle. It is in. Therefore, the number of cycles immediately after start-up is counted every 720 ° CA, and a correction count KSYCST is set according to the number of cycles.
[0049]
Specifically, using the relationship shown in FIG. 7, the correction coefficient KSYCST is calculated according to the water temperature Tw and the number of cycles. In FIG. 7, three characteristic lines L1 ′, L2 ′, and L3 ′ are set for each water temperature Tw (Tw = 0 ° C. or more, −20 to 0 ° C., −40 to −20 ° C.). In each of the characteristic lines L1 ′ to L3 ′, the number of cycles with KSYCST = 1 is the number of cycles that the engine 10 is considered to have completed. Here, in the characteristic line L1 ′ where the water temperature Tw is relatively high, a smaller KSYCST value is set in the process until the complete explosion (cycle number = 3). In the characteristic line L3 ′ where the water temperature Tw is relatively low, a larger KSYCST value is set in the process until the complete explosion (cycle number = 5).
[0050]
In such a case, the fuel injection amount TAU [msec] is calculated by the following equation (2).
TAU = TAUST / KSYCST / Kst (2)
According to the present embodiment using FIG. 7 described above, the NE increase degree at the start of the engine is not constant due to the difference in engine friction, that is, for example, the NE increase degree at the first explosion at a very low temperature is relatively small. Even in such a case, the fuel amount can be corrected according to the difference in the degree of NE increase.
[0051]
In this way, when the required fuel amount at the start is corrected by the number of cycles, the TAU value does not change immediately after the first explosion in the middle of one cycle (within 720 ° CA), and the engine 10 can be operated in a stable state. Incidentally, it is also possible to set the correction coefficient using the number of combustions of each cylinder instead of the number of cycles.
[0052]
(Another form 2)
Instead of the above embodiment in which the rotation correction coefficient KNEST corresponding to the engine speed NE is set, a correction coefficient KVST corresponding to the valve opening time [msec] of the intake valve 16 is set. That is, the correction coefficient KVST is set according to the valve opening time [msec] of the intake valve 16 accompanying the rotation of the crankshaft.
[0053]
Specifically, using the relationship shown in FIG. 8, the correction coefficient KVST is calculated according to the water temperature Tw and the valve opening time. 8, three characteristic lines L1 ″, L2 ″, L3 ″ are set for each water temperature Tw (Tw = 0 ° C. or more, −20 to 0 ° C., −40 to −20 ° C.) Here, the valve A short valve opening time means a high NE region, and conversely a long valve opening time means a low NE region.
[0054]
In such a case, the fuel injection amount TAU [msec] is calculated by the following equation (3).
TAU = TAUST / KVST / Kst (3)
That is, the relationship in FIG. 8 is obtained by replacing the engine speed NE on the horizontal axis in FIG. 5 with the valve opening time, and the longer the valve opening time, the more the starting fuel amount is corrected. To do. As described above, even when the NE increase degree at the time of starting the engine is not constant due to the difference in the engine friction (water temperature Tw), the fuel amount correction according to the difference in the NE increase degree can be performed.
[0055]
(Another form 3)
At the time of engine start, for example, the presence or absence of misfire is determined based on the engine speed NE, and the fuel injection amount TAU is increased and corrected at the time of misfire. The purpose of this is to perform correction on the increase side in addition to the increase correction based on the rotation correction coefficient KNEST, correction coefficients KSYCST, and KVST.
[0056]
(Another form 4)
In the above embodiment, the degree of increase in the rotational speed NE at the time of starting the engine is determined according to the water temperature Tw, but this is changed. For example, the engine temperature may be estimated based on the outside air temperature, the elapsed time since the previous engine stop, or the like, and the degree of increase in the engine speed NE at the time of engine start may be obtained according to the estimated value of the engine temperature. The point is that the NE injection degree corresponding to the engine friction at the time of starting the engine is reflected in the fuel injection control.
[0057]
(Another form 5)
In the TAU calculation routine of FIG. 2, the complete explosion determination rotational speed STBNE is variably set according to the water temperature Tw, but this complete explosion determination rotational speed STBNE is set to a fixed value. In this case, the processing load on the ECU 30 can be reduced by omitting the STBNE value search process.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an outline of a fuel injection control device for an internal combustion engine in an embodiment of the invention.
FIG. 2 is a flowchart showing a TAU calculation routine.
FIG. 3 is a diagram showing a relationship between a water temperature and a complete explosion determination rotational speed.
FIG. 4 is a diagram showing a relationship between a water temperature and a starting fuel amount.
FIG. 5 is a diagram showing a relationship between an engine speed and water temperature and a rotation correction coefficient KNEST.
FIG. 6 is a time chart for specifically explaining the operation in the embodiment.
FIG. 7 is a diagram showing the relationship between the cycle number and water temperature and the correction coefficient KSYCST in another embodiment.
FIG. 8 is a diagram showing the relationship between the intake valve opening time and water temperature and the correction coefficient KVST in another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Injector, 10 ... Engine (internal combustion engine), 16 ... Intake valve, 24 ... Rotational speed sensor as rotational speed detection means, 26 ... Temperature sensor as temperature detection means, 30 ... Fuel amount calculation means at start, 1st ECU (electronic control unit) as a correction means, a second correction means, a fuel amount correction means, a complete explosion determination means, and a complete explosion determination value setting means.

Claims (7)

A fuel injection control device for controlling a fuel injection amount at the start of an internal combustion engine,
A rotational speed detection means for detecting the engine rotational speed;
In the process from the first explosion to the complete explosion of the internal combustion engine, a starting fuel amount calculating means for calculating a starting fuel amount;
Similarly, in the process from the first explosion to the complete explosion of the internal combustion engine, the first correction means for correcting the calculated starting fuel amount to the increase side as the engine speed is lower;
When the fuel amount is corrected by the first correction means, the correction amount calculated based on the engine speed is increased as the degree of increase in the engine speed is reduced, and the correction is performed according to the degree of increase in the engine speed at that time. A fuel injection control device for an internal combustion engine, comprising: a second correction unit that changes the amount of increase / decrease . 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the second correction unit is configured to reduce a difference in increase / decrease in a correction amount due to a difference in the degree of increase in the rotational speed as the internal combustion engine is almost exhausted. . The second correction means gradually increases the difference in the amount of increase / decrease in the correction amount due to the difference in the degree of increase in the rotational speed with the passage of time from the initial explosion of the internal combustion engine, and then the rotational speed becomes closer to the complete explosion. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the difference in the amount of increase / decrease in the correction amount due to the difference in the degree of increase is gradually reduced. Temperature detecting means for detecting the engine temperature,
The said 2nd correction | amendment means that the correction amount by the said 1st correction | amendment means is enlarged, assuming that the raise degree of the said rotation speed is so small that the said detected engine temperature is low. Fuel injection control device for internal combustion engine. The first correction means uses the number of combustion cycles from the start of the engine instead of the engine speed, and corrects the calculated start-up fuel amount to the increase side as the number of cycles decreases. Item 5. The fuel injection control device for an internal combustion engine according to any one of Items 4 to 5. The first correction means uses the valve opening time of the intake valve instead of the engine speed, and corrects the calculated starting fuel amount to the increase side as the valve opening time is longer. The fuel injection control device for an internal combustion engine according to claim 4. A complete explosion determination means for determining whether or not the internal combustion engine has reached a complete explosion;
  A complete explosion determination value setting means for setting a complete explosion determination value by the complete explosion determination means in accordance with the engine temperature;
The fuel injection control device for an internal combustion engine according to any one of claims 1 to 6, further comprising:

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