JP3413965B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, when an engine is started, in order to prevent an overrich due to a leaked fuel of an injector (fuel injection valve) when the engine is stopped, the leaked fuel of the injector is estimated from the engine stop time, and the fuel is reduced accordingly. There is a technology (Japanese Patent Laid-Open No. 63-195356, Japanese Utility Model Laid-Open No. 62-101047).

[0003]

However, it is very difficult to estimate the leaked fuel from the injector while the engine is stopped. That is, fuel leakage occurs due to incomplete oil tightness of the injector valve seat portion, but the incomplete oil tightness of the seat portion varies depending on the product due to manufacturing variations. Therefore, the leaked fuel is, for example, about 0 to 7 mm ³
/ Min and various.

However, the prior art does not consider the case where there is a variation in leaked fuel. Therefore, when an injector with no fuel leakage (leakage fuel = 0 mm ³ / min) is attached to the engine, although there is no actual leakage, in the prior art, the leakage fuel is estimated from the engine stop time and the fuel injection is performed. Since the amount is reduced, there is a concern that misfire due to lean may occur and a large amount of HC may be discharged.

Therefore, an object of the present invention is to reduce the emission of HC regardless of whether or not there is fuel leakage from the fuel injection valve while the internal combustion engine is stopped, and to ensure stable startability. The present invention is to provide a fuel injection control device.

[0006]

The invention according to claim 1 is a fuel injection valve for injecting fuel into an intake system of an internal combustion engine,
In a fuel injection control device for an internal combustion engine, comprising: a fuel injection control unit that drives the fuel injection valve to control a fuel injection amount, the fuel injection control unit controls the internal combustion engine until a predetermined cycle after starting the internal combustion engine. Fuel injection of an internal combustion engine in which the fuel amount on the rich side near the fuel amount that becomes the lean side misfire limit when there is no fuel leakage from the fuel injection valve when the engine is stopped is injected from the fuel injection valve The main point is the control device.

According to a second aspect of the invention, the rich side fuel amount near the lean side misfire limit in the first aspect of the invention means the lean side misfire limit fuel amount. On the other hand, the gist of the present invention is a fuel injection control device for an internal combustion engine in which the amount of fuel is shifted to the rich side by the lean side allowable maximum value of the system tolerance related to the air-fuel ratio.

According to a third aspect of the present invention, in the first aspect of the invention, the internal combustion engine is configured to shift the fuel amount to the rich side as the cycle elapses until a predetermined cycle after the start of the internal combustion engine. The fuel injection control device of the present invention is the gist.

According to a fourth aspect of the present invention, in the first aspect of the invention, the internal combustion engine is arranged so that the fuel amount is shifted to the rich side as the intake stroke elapses until a predetermined cycle after the start of the internal combustion engine. The fuel injection control device of the engine is the gist.

According to a fifth aspect of the present invention, in the first aspect of the invention, a cylinder that abnormally burns due to rich is detected and a cylinder that abnormally burns is stored until a predetermined combustion cycle after the start of the internal combustion engine. However, the gist is a fuel injection control device for an internal combustion engine, which is configured to reduce the fuel amount of the cylinder from the next start of the internal combustion engine.

According to a sixth aspect of the present invention, there is provided a fuel injection control device for an internal combustion engine, wherein the stored contents of the fifth aspect of the invention are the abnormally burned cylinder and a correction coefficient for reducing the amount of the cylinder. Use as a summary.

According to a seventh aspect of the present invention, the temperature range of the internal combustion engine when the internal combustion engine is stopped and the time from the stop of the internal combustion engine to the start of the internal combustion engine are defined in the memory area of the sixth aspect of the invention. Alternatively, the gist is a fuel injection control device for an internal combustion engine that is divided by an element corresponding thereto.

The invention according to claim 8 is, in the invention according to claim 5, a fuel injection control device for an internal combustion engine, wherein the fuel amount is reduced also for cylinders other than the cylinder that has abnormally burned. And

[0014]

According to the first aspect of the present invention, the fuel injection control means is provided on the lean side when there is no fuel leakage from the fuel injection valve when the internal combustion engine is stopped until a predetermined cycle after the start of the internal combustion engine. The fuel amount on the rich side in the vicinity of the fuel amount at the misfire limit is injected from the fuel injection valve.

As a result, when there is no fuel leakage from the fuel injection valve while the internal combustion engine is stopped, the air-fuel mixture into the combustion chamber becomes the rich side near the misfire limit on the lean side and is burned. Therefore, misfire due to lean is avoided and a large amount of H
Emission of C is avoided. Further, if there is fuel leakage from the fuel injection valve while the internal combustion engine is stopped, there is a considerable margin until the amount of HC discharged increases due to the rich air-fuel mixture in the combustion chamber, and there is a normal leakage fuel. A large amount of HC is avoided from being discharged. Further, even if the amount of leaked fuel is large, it is possible to minimize the emission of HC.

According to a second aspect of the present invention, in addition to the operation of the first aspect of the invention, the fuel injection control means causes the fuel amount that becomes the lean side misfire limit until a predetermined cycle after the start of the internal combustion engine. On the other hand, the amount of fuel deviated to the rich side by the lean side allowable maximum value of the system tolerance regarding the air-fuel ratio is injected from the fuel injection valve. Here, the system tolerance regarding the air-fuel ratio means a tolerance such as the injection characteristic of the fuel injection valve.

As a result, when there is no fuel leakage from the fuel injection valve while the internal combustion engine is stopped, and the system tolerance related to the air-fuel ratio deviates to the lean side by the lean side allowable maximum value, it is possible to move to the combustion chamber. The air-fuel mixture reaches the lean side misfire limit and is burned. Therefore, the misfire due to lean is avoided and the discharge of a large amount of HC is avoided.

According to the invention described in claim 3, in addition to the operation of the invention described in claim 1, the fuel amount is shifted to the rich side as the cycle elapses until a predetermined cycle after the start of the internal combustion engine. As a result, as the cycle progresses, the amount of fuel leaking from the fuel injection valve that diffuses or remains in the intake system of the internal combustion engine decreases, but by shifting to the rich side, more stable combustion and increased emissions are also achieved. do not do.

According to the invention described in claim 4, in addition to the operation of the invention described in claim 1, the fuel amount is shifted to the rich side with the progress of the intake stroke until a predetermined cycle after the start of the internal combustion engine. As a result, with the progress of the intake stroke, the amount of fuel leaking from the fuel injection valve that diffuses or remains in the intake system of the internal combustion engine decreases, but by shifting to the rich side, more stable combustion and emission are also achieved. Does not increase.

According to a fifth aspect of the present invention, in addition to the operation of the first aspect of the invention, a large amount of fuel leaks from the fuel injection valve while the internal combustion engine is stopped until a predetermined combustion cycle after the start of the internal combustion engine. The cylinder that abnormally burned due to the rich when the occurrence of the occurrence is detected, and the cylinder that abnormally burned is stored. Then, the fuel amount of the cylinder is reduced from the next start of the internal combustion engine. As a result, HC due to abnormal combustion due to rich
It is possible to avoid a large amount of exhaust gas and deterioration of startability.

According to a sixth aspect of the invention, in addition to the operation of the fifth aspect of the invention, a cylinder that has abnormally burned and a correction coefficient for reducing the amount of the cylinder are stored, and the next start of the internal combustion engine. It is reflected in the reduction of the fuel amount in. Therefore, for example, more accurate fuel amount reduction is performed based on the number of abnormal combustion detections and the like.

According to a seventh aspect of the invention, in addition to the operation of the sixth aspect of the invention, the storage area is such that the temperature state of the internal combustion engine when the internal combustion engine is stopped and the state of the internal combustion engine after the internal combustion engine is stopped It is divided by the time to start or the element corresponding to it. Then, when the internal combustion engine is started next time, the fuel amount is reduced by using the data of the corresponding region. Therefore, the evaporated fuel can be accurately grasped by dividing the storage area, and highly accurate weight reduction is performed.

According to the invention described in claim 8, in addition to the operation of the invention described in claim 5, the fuel amount is reduced also in the cylinders other than the cylinder in which the abnormal combustion has occurred. Therefore, useless fuel injection is suppressed.

[0024]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall schematic view of a fuel injection control device for an internal combustion engine. The device is mounted on a vehicle. An intake pipe 2 and an exhaust pipe 3 are connected to a 4-cylinder spark ignition gasoline engine 1 as an internal combustion engine. An air cleaner 4 is provided in the most upstream part of the intake pipe 2, and the intake air is sucked into the intake pipe 2 from the air cleaner 4. A surge tank 5 is provided in the middle of the intake pipe 2. An injector (fuel injection valve) 6 is arranged in an intake pipe (intake port) 2 of each cylinder in the engine 1. Further, the fuel in the fuel tank 7 is sucked up by the fuel pump 8, supplied to the pressure regulator 10 through the fuel filter 9, regulated by the pressure regulator 10 and returned to the fuel tank 7.
The fuel whose pressure has been adjusted to this constant pressure is supplied to the injector 6. Then, the injector 6 is opened by the power supply from the battery 15. As a result, the fuel is injected and mixed with the intake air to form an air-fuel mixture, which is supplied to the combustion chamber 12 of each cylinder of the engine 1 via the intake valve 11.

A spark plug 13 is arranged in each combustion chamber 12 of each cylinder of the engine 1. Then, the igniter 14 generates a high voltage from the voltage of the battery 15, and the distributor 16 distributes the high voltage to the spark plug 13 of each cylinder.

A bypass passage 18 is formed so as to bypass the throttle valve 17 provided in the middle of the intake pipe 2, and an idle speed control valve 19 is arranged in the bypass passage 18. When the engine is idle, the engine speed is adjusted by adjusting the opening of the idle speed control valve 19.

An intake air temperature sensor 20 is provided at the most upstream portion of the intake pipe 2.
Is provided, and the intake air temperature can be detected by the sensor 20. Also, the throttle valve 17 of the intake pipe 2
A throttle opening sensor 21 is provided in the vicinity of the arrangement position of, and the opening of the throttle valve 17 can be detected by the throttle opening sensor 21. further,
The intake pipe internal pressure sensor 22 can detect the intake pipe internal pressure (intake pressure) in the surge tank 5.

The engine 1 is provided with a water temperature sensor 23 for detecting the temperature of engine cooling water. A cylinder discrimination sensor 24 and a crank angle sensor 25 are arranged in the distributor 16. The crank angle sensor 25 generates a crank angle signal for each predetermined crank angle associated with the rotation of the crank shaft or the cam shaft of the engine 1.
The cylinder discrimination sensor 24 also generates a cylinder discrimination signal for each specific position of a specific cylinder associated with rotation of the crankshaft or camshaft of the engine 1. More specifically, as shown in FIG. 8, the cylinder discrimination sensor 24 outputs two types of cylinder discrimination signals and the crank angle sensor 25 outputs a crank angle signal. Here, the cylinder discrimination signal is a signal for knowing where the engine is now, and in the embodiment of FIG. 8, the compression TDC of the first cylinder and the compression TDC of the fourth cylinder.
Is a signal generated at.

The cylinder discriminating signal is a signal for detecting the specific position of the specific cylinder (for example, the compression TDC of the first cylinder) at least once in the crankshaft 720 ° C., and the crank angle signal is the crank shaft 180 ° A. It is a signal that is generated a plurality of times and that is generated at a cycle of at least 30 ° C. or less.

In FIG. 1, the exhaust pipe 3 of the engine 1 is provided with an oxygen concentration sensor 26.
6, the oxygen concentration in the exhaust gas of the engine 1 can be detected.

Further, the engine 1 is provided with a starter motor (not shown), and the starter motor is the battery 1
The engine 1 is started (cranked) by being driven by the electric power supplied from the engine 5.

An electronic control unit (hereinafter referred to as ECU) 27 as fuel injection control means is mainly composed of a microcomputer. A signal associated with the drive of the starter motor from the starter switch 28 is input to the ECU 27. Further, the ECU 27 includes an intake air temperature sensor 20, a throttle opening sensor 21, an intake pipe pressure sensor 22, a water temperature sensor 23, a cylinder discrimination sensor 24, a crank angle sensor 25,
And an oxygen concentration sensor 26 are connected. And E
The CU 27 inputs signals from these sensors to detect the intake air temperature, the opening degree of the throttle valve 17, the intake pipe internal pressure (intake pressure), the engine cooling water temperature, the exhaust gas oxygen concentration, the engine speed, and the like.

The battery 15 is connected to the ECU 27, and the ECU 27 detects the voltage of the battery 15. Further, an injector 6 is connected to the ECU 27, and the ECU 27 drives the injector 6 (adjusts the valve opening time) to control the fuel injection amount.

Next, the operation of the fuel injection control device for an internal combustion engine configured as described above will be described. 2 to 7 show the ECU
27 shows a process (flow chart) executed by 27. Less than,
The processing of the ECU 27 will be described with reference to FIG.

In FIG. 8, a indicates a starter signal,
b and c indicate a cylinder discrimination signal which is alternately generated every 360 ° C. A, d is a crank angle signal which is generated every predetermined angle (for example, every 30 ° C. A), and e is the injection of the first cylinder, f,
g and h indicate the injections of the third, fourth and second cylinders, respectively.

In FIG. 2, when the starter switch 28 is turned on and the starter motor is driven, the routine process is started. Then, the ECU 27 executes step 10
At 1, it is determined whether or not it is the asynchronous injection timing at startup. In the present embodiment, this timing indicates whether or not 50 msec has elapsed after the starter switch 28 was turned on. If the ECU 27 determines that it is the asynchronous injection timing at start-up (timing t1 in FIG. 8), step 102
The injector 6 executes the asynchronous injection for all cylinders simultaneously.

FIG. 3 shows the calculation process of the asynchronous injection pulse at the time of starting in step 102 of FIG. The same processing is started by turning on the starter switch 28 (starting drive of the starter motor). ECU2
In step 201, the water temperature THW, the intake air temperature THA, and the intake pressure Pm are detected in step 201, and in step 202, the starting asynchronous injection pulse TASY corresponding to the water temperature THW at that time is calculated using the map of FIG. Further, the ECU 27 executes step 20.
In step 3, the correction coefficient FTHA corresponding to the intake air temperature THA is obtained using the map of FIG. 10, and the starting asynchronous injection pulse TASY is multiplied by the correction coefficient FTHA to obtain the starting asynchronous injection pulse TASY.
For the air density (TASY ← TASY
・ FTHA). Then, in step 204, the ECU 27 uses the map of FIG. 11 to correct the correction coefficient FPM according to the intake pressure Pm.
Is calculated, and the correction coefficient FPM is added to the asynchronous injection pulse TASY at startup.
Is multiplied by to correct the asynchronous injection pulse TASY at the start regarding the air density by the atmospheric pressure (intake pressure Pm) (TASY ← TASY · FPM).

Further, the ECU 27 detects the battery voltage BAT in step 205, and calculates the invalid injection pulse TV corresponding to the battery voltage BAT in step 206. Then, in step 207, the ECU 27 calculates the final injection pulse TAU (= TASY + TV) by adding the invalid injection pulse TV to the starting asynchronous injection pulse TASY.

The method of setting the starting asynchronous injection pulse TASY in steps 202 to 204 will be described below. The asynchronous injection pulse TASY at startup is set so that the air-fuel ratio (A / F) is as lean as possible for combustion. In other words, the system relating to the air-fuel ratio (A / F) has a tolerance, and the lean side (lean side maximum allowable value) of the system tolerance relating to the A / F indicates that there is no fuel leakage from the injector 6 when the engine is stopped. Set to reach the lean misfire limit.

This will be described in more detail with reference to FIG. FIG. 12 shows that the water temperature THW obtained by the study of the present inventors is 2
The relationship between the HC emission amount and the air-fuel ratio (A / F) with respect to the asynchronous injection pulse at startup at 5 ° C. is shown. Since this relationship differs depending on the engine model, the asynchronous injection pulse T at start
It is better to obtain the ASY setting for each engine model.

The system tolerance relating to the air-fuel ratio (A / F) includes the injection characteristic of the injector 6 (including the influence of valve deposit), the pressure regulating characteristic of the pressure regulator 10, the characteristic of the water temperature sensor 23, and the intake temperature sensor 20. Characteristic,
Characteristics of pressure sensor 22 in intake pipe, fuel pump 8 at startup
It can be calculated in consideration of the boosting characteristics of the engine, the variation of the lean misfire limit among the cylinders due to the influence of the compression ratio of the engine itself, the variation of the wall surface wet amount between the cylinders due to the influence of the shape of the intake port, the fuel properties, etc. . Air-fuel ratio (A / F)
The system tolerance relating to is generally about ± 20 to 40%. In addition, since the A / F has a slightly different wall wetness for each engine model, the proportion of fuel entering the combustion chamber differs. Therefore, the inclination of the A / F with respect to the asynchronous injection pulse slightly changes depending on the engine model due to the wet wall surface, as shown by the chain double-dashed line in FIG. Therefore, as shown in FIG. 12, the start-up asynchronous injection pulse TASY considering the wall wet is set to the injection pulse whose lean side (-) system tolerance limit becomes the lean misfire limit (about 14 to 1 in A / F).
8) Then, even if there is no fuel leakage from the injector 6, combustion can be performed, and even if there is fuel leakage,
Since the asynchronous injection pulse is set to be as lean as possible, the air-fuel mixture in the combustion chamber 12 becomes rich so that H
There is a considerable margin until the amount of C emission increases, and if the fuel is normal leakage fuel, it can be burned out of the HC large amount emission region without increasing HC. Also, even if it is a large amount of leaked fuel,
Although the air-fuel mixture to the combustion chamber 12 enters the HC large amount discharge area by rich partial combustion, the discharge of HC can be suppressed to the minimum.

That is, assuming that the system tolerance for A / F is ± 30%, assuming that the water temperature THW is 25 ° C., the intake air temperature THA is 20 ° C., and the intake pressure Pm is 760 mmHg, TASY = from FIG. 43 ms, as shown in FIG.
Since the correction coefficient FTHA = 1 and FPM = 1 of 11 are obtained, the corrected TASY = 43 ms. In FIG. 12, TASY =
43 ms is a pulse width (30 / 0.7) that is deviated by -30% from the lean side maximum allowable value, which is the lean side misfire limit value when there is no fuel leakage from the injector 6 when the engine is stopped. = 43).

In FIG. 8, this final injection pulse TAU
Asynchronous injection for all cylinders is performed only (t1 to t in FIG. 8).
2 timing). The ECU 27 also executes the process shown in FIG. 4 for each predetermined crank.

In step 301, the ECU 27 determines whether or not it is the first synchronous injection, and if it is the first synchronous injection, the ECU 27 waits in step 302 for detection of a cylinder discrimination signal. And
When the cylinder discrimination signal is detected by the ECU 27 (t3 in FIG. 8).
Timing), and after confirming that the asynchronous injection at startup is completed in step 303, the process proceeds to step 304. In step 304, the ECU 27 calculates the asynchronous injection start timing (time) TAS and the asynchronous injection end timing (time) TAF by calculating the time backward from the cylinder determination time point (timing t3) as shown in FIG. That is, TAS,
The angle is converted from the TAF time and the engine speed Ne. Then, in step 305, the ECU 27 determines at which position in each cylinder the asynchronous injection is performed based on the asynchronous injection start timing TAS and the asynchronous injection end timing TAF.

The ECU 27 proceeds to step 306,
From the asynchronous injection start / end positions obtained in step 305, the first synchronous injection timing of each cylinder is obtained. Here, the method of determining the first synchronous injection timing of each cylinder is such that the asynchronous injection fuel and the first synchronous injection fuel of each cylinder are not overlapped in the same intake stroke, and the fuel supply is lost in the intake stroke. It is the timing at which injection can be performed without That is, the synchronous injection is started from the cylinder in which the fuel by the asynchronous injection is first sucked.

As described above, it is possible to correct fuel amount by preventing the fuel from overlapping or coming out during the intake stroke, and to prevent the increase of emission without supplying unnecessary fuel. Further, if the asynchronous injection overlaps the closing timing of the intake valve 11 and the asynchronous injection timing is such that the asynchronous injection is divided into the next strokes, the fuel amount of the cylinder at the next synchronous injection timing is reduced. This enables more accurate fuel metering.

Subsequently, it is determined in step 307 of FIG. 4 whether or not the injection timing has come, and when the injection timing comes, the synchronous injection is executed in step 308 (t4 in FIG. 8).
~ T5, t6-t7, t8-t9).

In FIG. 8, the injection timing is 100 ° CA after the cylinder discrimination time in the first and third cylinders (Te = Tf = 100 ° CA), and 280 ° in the fourth cylinder.
When CA has elapsed (Tg = 280 ° CA), 46 in the second cylinder
It is assumed that 0 ° CA has elapsed (Th = 460 ° CA).

At this time, in the case of the first cylinder, since the asynchronous injection fuel has already been sucked in, the injection is started after Te has elapsed since the cylinder discrimination signal was detected. Te is the time for avoiding driving the injector 6 at TDC. That is, in TDC, the rotational resistance of the engine 1 is large and the load of the battery 15 is large. This prevents the battery voltage from decreasing during cranking by the starter motor, and prevents the injector 6 from falling below the minimum operating voltage. In the case of the fourth cylinder, the asynchronous injection fuel is sucked in after the first cylinder discrimination signal is detected. Therefore, the first synchronous injection is executed after Tg after the intake stroke.

Further, here, it is preferable that the synchronous injection at the time of starting is performed at the earliest possible timing with respect to the intake stroke.
This is because it is possible to obtain sufficient fuel evaporation time, start with less fuel, and reduce emissions.

In this embodiment, the synchronous injection is independent injection, but it may be two group injection. Further, in FIG. 8, in order to increase the evaporation time of the synchronous injection fuel of the third cylinder,
After the cylinder discrimination (after Tf), the injection is performed at an early timing, and as a result, the injection is performed at the same timing as the synchronous injection of the first cylinder. Therefore, it suffices to perform the injection in each cylinder at a timing such that the evaporation time can be long, and the injection timings of the first cylinder and the third cylinder do not necessarily have to be the same.

On the other hand, if it is not the first synchronous injection after the start of starting in step 301 of FIG. 4, that is, 2 after the start of starting.
If it is the synchronous injection after the first time, it is judged in step 309 whether or not the injection timing has come, and if it becomes the injection timing, the synchronous injection is executed in step 310.

FIGS. 5, 6 and 7 show the calculation processing of the synchronous injection pulse in steps 308 and 310 in FIG. The routine process is started every predetermined crank. In FIG. 5, the ECU 27 determines in step 401 whether or not the first synchronous injection of each cylinder has ended. If the first synchronous injection of each cylinder has not ended, step 27 in FIG.
Move to 02.

In step 402, the ECU 27 detects the water temperature (THW), the intake air temperature (THA), and the intake pressure (Pm), and in step 403, the water temperature (TW) is detected using the map of FIG.
(HW) The first synchronous injection pulse TASY1 for each cylinder is calculated. At step 404, the ECU 27 obtains the correction coefficient FTHA according to the intake air temperature THA using the map of FIG.
Correction coefficient FTHA for the first synchronous injection pulse TASY1 of each cylinder
Is multiplied by to correct the air density for the first synchronous injection pulse TASY1 of each cylinder (TASY1 ← TASY1 ・ FTH
A). Then, in step 405, the ECU 27 obtains the correction coefficient FPM according to the intake pressure Pm using the map of FIG. 11, and the correction coefficient FPM is added to the first synchronous injection pulse TASY1 of each cylinder.
PM is multiplied and correction for air density due to atmospheric pressure (intake pressure Pm) is performed on the first synchronous injection pulse TASY1 of each cylinder (TASY1 ← TASY1 · FPM).

The reason why the asynchronous injection pulse TASY in the first cycle after the start of operation and the synchronous injection pulse TASY1 in the first cycle of each cylinder are set to different values is as follows.
That is, assuming that there is no fuel leakage from the injector 6 when the engine is stopped (assuming that there is no wall-adhering fuel in the intake port or the like at the first asynchronous injection after the start of start), a large amount is obtained during asynchronous injection. Is supplied, and the fuel adhered to the wall surface is sucked in the intake stroke of the second cycle after the start of the engine overlapping with the first synchronous injection of each cylinder. Therefore, the synchronous injection pulse TASY1 for the first time in each cylinder may be smaller than the asynchronous injection pulse TASY for the first cycle after the start of starting.

Further, in step 401 of FIG. 5, each cylinder 1
The reason why the synchronous injection for the first time and the synchronous injection for the second time and thereafter for each cylinder are separated is that the synchronous injection pulse TASY1 for the first time for each cylinder is 2
This is because it is different from the pulse required for the synchronous injection after the first time. That is, if the fuel leaks from the injector 6 when the engine is stopped, the leaked fuel from the injector 6 when the engine is stopped is sucked in the intake stroke of the second cycle after the start of the engine. That is, the fuel leaked from the injector 6 while the engine is stopped evaporates at a particularly high temperature, diffuses to the intake port, the surge tank 5, and the vicinity of the throttle valve 17, and is liquefied at a low temperature. Therefore, in the intake stroke of each cylinder once, all the leaked fuel is not sucked in,
The fuel remaining in the intake system of the surge tank 5 or the like will be sucked in during the second and subsequent intake strokes. Here, the maximum number of times of intake varies depending on the engine displacement and the volume of the intake system, and therefore varies from engine to engine. (In the present embodiment, it is assumed that the fuel is sucked up to the second cycle. Generally, it is 1 to 3 cycles.) As described above, in consideration of the fact that the leaked fuel of the injector 6 is sucked, FIG. As shown, the first synchronous injection pulse of each cylinder is set as lean as possible like the asynchronous injection pulse.

That is, assuming that the system tolerance for A / F is ± 30%, assuming that the water temperature THW is 25 ° C., the intake air temperature THA is 20 ° C., and the intake pressure Pm is 760 mmHg, TASY1 = FIG. It becomes 11 ms, and Fig. 1
Since the correction coefficients FTHA = 1 and FPM = 1 for 0 and 11,
The corrected TASY becomes 11 ms. In FIG. 14, TAS
Y1 = 11 ms is a maximum allowable lean side value of −30 with respect to a pulse width of 7.5 ms, which is the lean side misfire limit value in the second cycle after starting the engine when there is no fuel leakage from the injector 6 when the engine is stopped. The pulse width is deviated by% (7.5 / 0.7 = 11).

Subsequently, the ECU 27 executes step 40 in FIG.
In step 6, the first synchronous injection pulse TASY1 of each cylinder is set as the effective injection pulse TAUE. Then, the ECU 27 proceeds to step 407 of FIG. 5 and at step 407, the battery voltage BA
T is detected, and in step 408, the invalid injection pulse TV is calculated according to the battery voltage BAT. And the ECU 2
7 is the final injection pulse TAU (= TAUE by adding the invalid injection pulse TV to the effective injection pulse TAUE in step 409).
+ TV) is calculated.

On the other hand, the ECU 27 executes step 401 in FIG.
If the first synchronous injection for each cylinder has ended (that is, the second synchronous injection has taken place) in step 41,
Move to 0. In step 410, the ECU 27 determines whether or not the current engine speed Ne is lower than 400 rpm, and if Ne <400 rpm, the process proceeds to step 411. Then, the ECU 27 determines in step 411 whether or not the previous engine speed Ne is 400 rpm or more,
If it is less than 400 rpm, the process proceeds to step 413 and 40
If 0 rpm or more, in step 412, it is determined whether or not the engine speed Ne this time is 200 rpm or less. ECU2
7 is after the processing of step 411, or step 41
If the engine speed Ne this time is 200 rpm or less in 2 (when the engine is started), in step 413, the water temperature THW,
The intake air temperature THA and the intake air pressure Pm are detected, and in step 414, the starting injection pulse TSTA is calculated according to the water temperature THW. Then, in step 415, the ECU 27 obtains the correction coefficient FTHA according to the intake air temperature THA by using the map of FIG. 10, multiplies the start-time injection pulse TSTA by the correction coefficient FTHA, and relates to the air density with respect to the start-time injection pulse TSTA. Make a correction (TSTA ← TSTA · FTHA). And the ECU
27, in step 416, the correction coefficient FPM corresponding to the intake pressure Pm is calculated using the map of FIG.
STA is multiplied by the correction factor FPM to start injection pulse TSTA
Then, the air density is corrected by the atmospheric pressure (intake pressure Pm) (TSTA ← TSTA · FPM).

Further, in step 417, the ECU 27 sets the starting injection pulse TSTA to the effective injection pulse TAUE.
Further, the ECU 27 determines in step 407 that the battery voltage B
AT is detected, and in step 408, the invalid injection pulse TV is calculated according to the battery voltage BAT. And the ECU
27 is a final injection pulse TAU (= TAU) by adding the invalid injection pulse TV to the effective injection pulse TAUE in step 409.
Calculate E + TV).

On the other hand, the ECU 27 determines in step 410 that the current engine speed Ne is 400 rpm or more, or in step 412 that the current engine speed Ne is 200 rp.
If m or more (after engine start), step 4 in FIG.
Go to 18.

The ECU 27 detects the engine speed Ne in step 418, and detects the intake pressure Pm in step 419. Then, the ECU 27 calculates the intake pressure change amount ΔPm in step 420, and detects the intake temperature THA in step 421. Further, the ECU 27 detects the water temperature THW in step 422, and in step 423 the throttle opening TA
To detect. Subsequently, the ECU 27 detects the oxygen concentration in the exhaust gas in step 424, and calculates the basic injection pulse Tp in step 425 according to the engine speed Ne and the intake pressure Pm. Then, the ECU 27 determines in step 426 the water temperature T
The water temperature correction coefficient FWL is calculated according to HW, and step 42
In step 7, the post-start correction coefficient FASE is calculated according to the water temperature THW and the elapsed time after start. Further, the ECU 27 executes step 4
In step 28, an intake air temperature correction coefficient FTHA is calculated according to the intake air temperature THA, and in step 429, a high load correction coefficient FOTP is calculated according to the throttle opening TA, the engine speed Ne and the intake pressure Pm.
To calculate.

Next, in step 430, the ECU 27 determines the air-fuel ratio feedback correction coefficient F according to the oxygen concentration in the exhaust gas.
A / F is calculated, and in step 431, the acceleration correction pulse TACC is calculated according to the intake pressure change amount ΔPm. And EC
U27 calculates the effective injection pulse TAUE using the following equation in step 432.

TAUE = Tp.FWL.FTHA. (FASE +
After calculating the effective injection pulse TAUE in step 432, the ECU 27 proceeds to step 407 in FIG. Then, as described above, the ECU 27 calculates the invalid injection pulse TV according to the battery voltage BAT in steps 407 and 408, and adds the invalid injection pulse TV to the effective injection pulse TAUE in step 409 to add the final injection pulse TAU (= TAUE + TV) is calculated.

As described above, in this embodiment, the ECU 27
Until the intake stroke of 2 cycles after starting the engine 1,
The fuel amount that becomes the lean side misfire limit when there is no fuel leakage from the injector 6 when the engine is stopped (Fig. 12
The fuel amount on the rich side in the vicinity of 30 ms (7.5 ms in FIG. 14) is injected from the injector 6. As a result, when there is no fuel leakage from the injector 6 while the engine 1 is stopped, the air-fuel mixture into the combustion chamber 12 becomes the rich side near the misfire limit on the lean side and is burned.
Therefore, the misfire due to lean is avoided and the discharge of a large amount of HC is avoided. If fuel leaks from the injector 6 while the engine 1 is stopped, the combustion chamber 1
Since the air-fuel mixture into 2 becomes rich, there is a considerable margin until the amount of HC discharged increases, and a large amount of HC is avoided if the amount of leaked fuel is normal. Further, even if the amount of leaked fuel is large, it is possible to minimize the emission of HC. In this way, it is possible to reduce HC emissions regardless of whether fuel is leaking from the injector 6 while the engine 1 is stopped, and to ensure stable startability without misfire.

As the rich side fuel amount near the lean side misfire limit, the lean side misfire limit fuel amount is richer than the lean side allowable maximum value of the system tolerance regarding the air-fuel ratio. The amount of fuel slid to the side. As a result, when there is no fuel leakage from the injector 6 while the engine 1 is stopped and the system tolerance related to the air-fuel ratio deviates to the lean side by the lean side allowable maximum value, the air-fuel mixture to the combustion chamber 12 is It becomes the limit of misfire on the lean side and is burned. Therefore, the misfire due to lean is avoided and the discharge of a large amount of HC is avoided. As described above, even if there is a system tolerance regarding the air-fuel ratio, HC emission is reduced regardless of fuel leakage from the injector 6 while the engine 1 is stopped, and stable startability is ensured without misfire. It will be possible.

In addition, in the prior art (Japanese Patent Laid-Open No. 63-195356).
In Japanese Laid-Open Patent Publication No. 62-101047), it is necessary to measure the elapsed time while the engine is stopped, and wasteful power and circuit are required. However, in the present embodiment, HC emission can be reduced and stable startability can be secured without measuring the stop time of the engine 1.

The application of this embodiment may be carried out in the following modes. For example, in the above embodiment, the asynchronous injection start timing TAS and the asynchronous injection end timing TAF are calculated by calculating backward from the cylinder determination time in step 304 of FIG.
When calculating, the angle was converted from the time of TAS, TAF and the engine speed Ne as a method of back calculation, but the pulse number of the crank angle signal was counted up from the injection start and end times to the cylinder discrimination. May be. This one
There is no Ne error, and it can be obtained more accurately.

Further, in the above embodiment, it is assumed that the leaked fuel of the injector 6 is sucked up to the intake stroke of the second cycle after the start of the engine, and the amount of fuel sucked in the intake stroke of the second cycle (up to the first synchronous injection). ) Was set to the lean side,
Depending on the engine, there is a case where the fuel leaks and is sucked up to the intake stroke of the third cycle or later, and at that time, the injection of the third cycle or later may be set to the lean side.

Furthermore, two cycles after the start of engine start,
Since the leaked fuel of the injector that diffuses or remains in the intake system decreases every three cycles,
When the fuel injection amount gradually shifts from the lean side to the rich side, combustion becomes more stable and the emission does not increase. As a method of gradually shifting from the lean side to the rich side, it may be performed every cycle or every intake stroke. If it is performed for each intake stroke, it can be made richer more accurately as required. For example, when shifting the fuel injection amount from the lean side to the rich side in each cycle, FIG. 15 may be used. This FIG. 15 corresponds to FIG. 13, and the characteristic line L1 of FIG. 15 is used for the second cycle (first synchronous injection) after the start of starting, and for the third cycle (second synchronous injection) after the start of starting. The characteristic line L2 in FIG. 15 may be used.

Further, in the above embodiment, the asynchronous injection execution timing is performed in synchronization with the starter, but it may be performed by the crank angle signal (for example, the crank angle signal first received after the starter is turned on). In that case, when the asynchronous injection start timing is calculated backward, by counting up the number of crank signals until cylinder discrimination, there is no conversion error as compared with the backward calculation method using time and Ne, and more accurate calculation can be performed. (Second Embodiment) Next, the second embodiment will be described focusing on the differences from the first embodiment.

The present embodiment is abnormal due to the richness when a large amount of fuel leaks from the injector 6 while the engine 1 is stopped, in contrast to the combustion by the fuel after the asynchronous injection at the engine start in the first embodiment. The burned cylinder is detected and the asynchronous injection fuel to the cylinder is reduced at the next engine start. In this embodiment, as shown in FIG. 16, the ECU 27 is provided with a non-volatile memory 27a,
The nonvolatile memory 27a stores the data shown in FIG. This data is the abnormal combustion count value X _#k corresponding to the k value indicating the cylinder (hereinafter, cylinder count value k).
Is. In this embodiment, the cylinder count value k = 1, 2, 3, 4 since it is embodied as a 4-cylinder engine. or,
The abnormal combustion count value X _#k is prepared for each cylinder, and the abnormal combustion count value X _{# 1} for the first cylinder, the abnormal combustion count value X _{# 2} for the second cylinder, and the third cylinder The abnormal combustion count value X _{# 3} and the abnormal combustion count value X _{# 4} for the fourth cylinder are provided. The abnormal combustion count value X _#k takes one of "0", "1", "2", and "3",
X abnormal combustion by the rich to the k-cylinder at the time of _#k = 0 is not generated, abnormal combustion by the rich to the k-cylinder at the time of X _#k = 1 is meaning that has occurred once, X _#k = 2
Means that the abnormal combustion due to the rich occurs in the k cylinder twice, and means that the abnormal combustion due to the rich occurs in the k cylinder three times when X _#k = 3. The counting operation of the abnormal combustion count value X _{# k} will be described later. Further, the abnormal combustion due to rich is detected by whether or not the increase in the engine speed due to ignition (combustion) is a predetermined value or more. This determination process will be described later.

Instead of the non-volatile memory 27a, a backup memory to which battery power is supplied even when the ignition key is turned off may be used. In short, what is necessary is that the stored contents are retained even when the engine is stopped.

Then, the ECU 27 is adapted to perform the processing of FIG. 18 instead of the processing of FIG. 3 of the first embodiment.
The ECU 27 also performs the processing of FIG. First, the process of FIG. 19 will be described with reference to FIG. This process
This routine is for _{obtaining the} abnormal combustion cylinder (k) due to rich and the number of times (abnormal combustion count value X _#k ), and this routine is 180 ° for each ignition (4 cylinders in this embodiment).
Every CA).

The ECU 27 determines in step 601 whether the counter value n is "4" or less. Here, the value n of the counter is a value corresponding to the number of ignitions after the ignition key is turned on, and the initial value n = 1 is set when the ignition key is turned on (when the computer is initially set). And
In FIG. 20, ignition timings t1, t2, t3, t
At 4 and t5, "1" is incremented in step 614 described later.

If the counter value n is "4" or less, the ECU 27 determines in step 602 the current engine speed Ne.
Is stored in the memory (RAM) as Ne (n). Then, the ECU 27 determines in step 603 whether or not the counter value n is "3" or more, and if it is less than "3", that is, n = 1 (first ignition) or n = 2 (second ignition). If it is ignition), n is incremented by "1" in step 614 and this routine ends.

That is, at the time of the first ignition (n = 1) after starting the engine 1, it is still unknown whether or not the cylinder normally burns due to the ignition, that is, the rotation increase due to the combustion is unknown. Therefore, the determination cannot be made. In addition, at the time of the second ignition after the start of the engine 1 (n
= 2), the reason why the abnormality determination is not performed is as follows.
In the present embodiment, since the asynchronous injection is performed in synchronization with the starter, at the time of the second ignition (n = 2) after the start of the engine 1, the cylinder in which the fuel by the asynchronous injection is first sucked is the intake valve 11. When it overlaps with the closing time, it will be divided and entered. As a result, the amount of fuel is small, and a sufficient increase in rotation cannot be obtained due to lean combustion, which may result in an erroneous determination. Therefore, the normal combustion determination regarding the first ignition is not performed.

As described above, the determination as to whether or not the combustion is normal is made at the time of the third ignition (n = 3). ECU 27
Is n ≧ 3 in step 603, step 6
In 04, the engine speed Ne of the previous time (before 180 ° CA)
The difference ΔN between (n-1) and the current engine speed Ne (n)
Find e (n). Based on this increase in rotation (ΔNe (n)), it is determined as follows whether the (n-1) th ignition has normally burned.

In step 605, the ECU 27 compares the comparison value Δ of whether or not the normal combustion of the HC in the low emission range is performed.
Read NeH. This comparison value ΔNeH is the rotation increase ΔN at the maximum fuel amount in the HC low emission range in FIG.
It is e. Since this comparison value ΔNeH differs for each engine model, it is obtained for each engine model. However, the comparison value ΔNeH needs to be smaller than the rotation increase ΔNe _min at the lean-side minimum value of the asynchronous injection pulse setting range, as shown in FIG. Therefore, as shown in FIG.
Rotational increase ΔNe 'at maximum fuel amount in low HC emission range
Is larger than the rotation increase ΔNe _min at the lean side minimum value of the asynchronous injection pulse setting range, a value (= ΔNe) obtained by subtracting a predetermined value α (for example, 30 rpm) from ΔNe _min.
min− α) is the comparison value ΔNeH.

The ECU 27 reads the water temperature THW in step 606 of FIG. 19, and in step 607 uses the map of FIG. 24 to obtain the correction coefficient k1 according to the water temperature THW. Further, the ECU 27 determines in step 608 the engine speed N
Engine speed N from e (n) using the map of FIG.
A correction coefficient k2 corresponding to e (n) is obtained.

Then, the ECU 27 executes step 6 in FIG.
At 09, the comparison value ΔNeH is corrected. This is step 6
To the comparison value ΔNeH obtained in 05, the correction coefficients k1 and k
It is performed by multiplying by 2 (ΔNeH ← ΔNeH · k
1 ・ k2). Here, the correction with the correction coefficient k1 is
This is because engine friction increases as the water temperature and lubricating oil temperature decrease, and the increase in rotation is slowed down. Also, the correction coefficient k2
The correction is performed because the engine friction increases with the increase of the engine rotation and the rotation increase is slow.

Subsequently, the ECU 27 proceeds to step 610.
Changes in engine speed ΔNe (n) and comparison value ΔNeH
And if ΔNe (n) ≧ ΔNeH, normal combustion
That the counter value n is determined in step 614.
"1" is incremented and this routine is finished. one
On the other hand, the ECU 27 determines ΔNe (n) <ΔN in step 610.
If eH, it is determined that the increase in rotation is slow and normal combustion is not occurring.
Then, in step 611, the (n-1) th ignition cylinder (#
k), and the abnormal combustion count value corresponding to that cylinder k
X_#kIs incremented by "1". And the value is
It is stored in the volatile memory 27a. Abnormal combustion count
Value X_#kX is initialized when shipped from the factory. _#k= 0
Has become.

Here, for example, as shown by the engine speed change line L in FIG. 20, n = 3 (third ignition)
Sometimes ΔNe (3) <ΔNeH in step 610 of FIG.
If it becomes, in step 611, (3-1) = second ignition, that is, the combustion by the ignition of the fourth cylinder is determined to be abnormal combustion, and X _{# 4} = 1 is set.

Further, the ECU 27 executes step 611 of FIG.
After performing the processing of (1), the abnormal combustion count value X _{# k} is prevented from becoming "4" or more in steps 612 and 613. That is, in step 612, it is determined whether the abnormal combustion count value X _#k is “4” or more. If X _#k ≧ 4, step 6
At step 13, X _{# k} = 0 is set. After that, the process proceeds to step 614 and the counter value n is incremented by "1".

On the other hand, the ECU 27 ends this routine when the value n of the counter becomes "5" or more in step 601. Next, the processing of FIG. 18 will be described with reference to FIG. This process is a process for calculating an asynchronous injection pulse at the time of starting, and the process is started by turning on the starter switch 28 (starting drive of the starter motor).

The ECU 27 determines in step 501 the water temperature THW.
And intake air temperature THA and intake air pressure Pm are detected, and step 502
Then, using the map of FIG. 9, the starting asynchronous injection pulse TASY corresponding to the water temperature THW at that time is calculated. Furthermore, EC
U27 obtains the correction coefficient FTHA according to the intake air temperature THA in step 503 using the map of FIG. 10, and multiplies the starting asynchronous injection pulse TASY by the correction coefficient FTHA to determine the air density for the starting asynchronous injection pulse TASY. Compensate (TASY ← TASY · FTHA). Then, the ECU 27
Is the intake pressure Pm using the map of FIG. 11 in step 504.
A correction coefficient FPM corresponding to is calculated, and the asynchronous injection pulse TASY at the start is multiplied by the correction coefficient FPM to correct the asynchronous injection pulse TASY at the start concerning the air density by the atmospheric pressure (intake pressure Pm) (TASY ← TASY・ FPM).

The ECU 27 sets the cylinder count value k to "1" in step 505. Then, the ECU 27 determines in step 506 whether or not the process has been completed up to the four cylinders. If the process is completed, the process proceeds to step 511, and if not completed, the process proceeds to step 507. In step 507, the ECU 27 determines whether or not the abnormal combustion count value X _#k stored in the nonvolatile memory 27a is “0”, that is, whether or not the k cylinder (initially k = 1) is abnormal. If it is "0", in step 508 the asynchronous injection pulse TASY at start is
Set _#k (k cylinder injection pulse) = TASY. On the other hand, when the abnormal combustion count value X _{# k} is other than "0" in step 507 and the cylinder concerned is abnormal combustion, the ECU 27 obtains the starting asynchronous injection pulse TASY _{# k} by the following equation in step 510. .

TASY _#k = TASY- (1/3) .TASY.X _#k Here, the subtraction is for setting the fuel amount on the lean side in order to prevent abnormal combustion due to rich. or,
Regarding the amount of subtraction, the pulse width of (1/3) TASY is subtracted in order to prevent it from entering the lean misfire area by reducing it all at once. Nevertheless, if abnormal combustion occurs, the above-mentioned FIG.
In step 611, X _#k = 2, so the pulse width of (2/3) TASY is subtracted at this time.

Thus, the abnormal combustion count value X _{# k} is
When it is "0", the reduction correction is not performed on the starting asynchronous injection pulse TASY, and when it is other than "0", the reduction correction according to the value is performed. That is, the abnormal combustion count value X
_#k is a correction coefficient for weight loss.

The ECU 27 executes step 508 or 51.
After processing 0, the cylinder count value k is incremented by "1" in step 509 and the process returns to step 506. By repeating steps 506 to 510 in this manner, the abnormal combustion count value X from the first cylinder to the fourth cylinder X
at start-up in accordance with the contents of the _#k seek the asynchronous injection pulse TASY _#k.

On the other hand, the ECU 27 determines k in step 506.
When> 5, in step 511 the battery voltage BAT
Is detected, and according to the battery voltage BAT in step 512,
The invalid injection pulse TV is calculated, and in step 513
Final injection pulse TAU to the cylinder _#kSet. That is,
Asynchronous injection pulse at start TASY_#kInvalid injection pulse TV
And the final injection pulse TAU_#k(= TASY_#k+ T
V) is calculated.

As a result, as shown in FIG. 20, when the combustion due to ignition of the fourth cylinder is judged to be abnormal combustion and X _{# 4} = 1 is established, as shown in FIG. Is subtracted from the fourth cylinder by (1/3) TASY.

As described above, in the present embodiment, in the first combustion cycle after the start of the engine 1, the cylinder abnormally burned due to rich is detected, and the data indicating the abnormally burned cylinder (X _#k = 1, 2, 3) X _{# k} is stored in the non-volatile memory 27a, and the fuel amount of the cylinder is reduced from the next engine 1 start. As a result, it is possible to prevent a large amount of HC from being discharged and deterioration of startability due to abnormal combustion due to rich air.

Further, the stored contents are stored in a cylinder that has abnormally burned, and a correction coefficient (that is, X
_{# k} = 1, 2, 3). Therefore, the number of times abnormal combustion is detected is reflected in the reduction of the fuel amount at the next start of the engine 1, and the fuel is accurately reduced.

Further, for the lean side, since the asynchronous injection pulse TASY at the start is determined in a region where lean misfire does not occur in consideration of system tolerance, if abnormal combustion occurs, it is estimated that rich combustion is caused by oil leak. it can. Therefore, it suffices to make a correction in the direction of reducing the fuel amount.
In Fig. 2, the convergence is better than that in the case where the combustion is performed in the low HC emission range by swinging to the lean side and the rich side with respect to the same area so as to converge in the same area.

The second embodiment may be applied in the following modes. (B) If the rotation speed does not increase when the amount is reduced, it is considered that the combustion is abnormal due to other factors, and therefore the amount may not be reduced. That is, the abnormal combustion count value X
_{Set #k} to “0” (return to the initial value).

(B) As shown in FIG. 26, the region for storing the abnormal combustion count value X _{# k} may be subdivided to accurately grasp the evaporated fuel and to perform the more accurate reduction. This region has a factor of the engine cooling water temperature THW when the engine is stopped (the temperature state of the engine when the engine is stopped) and the time when the engine 1 is stopped. The engine cooling water temperature THW is detected by the water temperature sensor 23, and the engine stop time is measured by measuring the time from turning off the ignition key for stopping the engine to turning on the starter switch 28 for starting the engine. Ask. That is, the fuel leaking from the injector 6 changes as shown in FIG. 27 depending on the water temperature when the engine is stopped and the engine stop time. The amount of evaporative fuel changes depending on the engine stop time, for example, when the water temperature at the time of stop is 80 ° C, leakage occurs immediately after the engine stops and the amount increases and the pressure in the fuel pipe increases in about 2 hours. Liquefaction starts, liquefaction starts, and the amount of evaporated fuel decreases thereafter. The reason why the amount of evaporated fuel changes depending on the water temperature when the engine is stopped is that the lower the water temperature, the less expansion of the fuel, the faster the pressure in the fuel pipe drops, and the lower the water temperature, the smaller the evaporation amount. .

As a data storage method, the water temperature THW when the engine is stopped and the engine stop time are stored in a memory, and when an abnormal judgment is made when the engine is started and abnormal combustion occurs, the data (X _{# k} ) is updated.
Further, as a fuel reduction method using the data, data data (X _#k ) in a region corresponding to the water temperature THW when the engine is stopped (in steps 506 to 510 of FIG. 18) and the engine stop time are used. Read out and reflect in fuel quantity.

In this case, instead of the engine stop time measured by the time from turning off the ignition key to turning on starter switch 28, the estimated engine stop time is used as a factor corresponding to the time from engine stop to engine start. You may use. The estimated engine stop time is estimated from, for example, the water temperature THW when the engine is stopped and the water temperature THW when the engine is started next time. That is, FIG.
Using the three-dimensional map shown in Fig. 8, data for obtaining the engine stop time is prepared in advance from the water temperature at the time of engine stop and the water temperature at the time of the next engine start. Water temperature at engine start of 60 ℃
Then, it is estimated that the engine stop time is 2 hours. Alternatively, the estimated engine stop time may be obtained using the temperature of the engine lubricating oil instead of the engine cooling water temperature.

(C) The reduction rate may be changed for each storage area shown in FIG. That is, for example, as shown in FIG. 27, the water temperature at the time of engine stop is 80 ° C., and the amount of evaporated fuel reaches a peak when 2 hours have elapsed since the engine was stopped. To

(D) It was determined that one cylinder had abnormally burned.
If determined, the other cylinders may be reduced. That is, an example
For example, as shown in FIG. 29, the leakage amount in the first cylinder (# 1)
If the injector 6 with a large number of
Even if there is no leakage of the vector 6
This is because the evaporated fuel diffuses into the. Therefore, for example
For example, when the first cylinder misfires in region VII of FIGS.
X_{# 1}= 1 and X_{# 2,}X_{# 3,}X_#Four= 0.2 and set
Set. Also, in the region I of FIGS. 26 and 29, the first cylinder misfired.
When the stop time is 0 to 30 minutes, it will be expanded to other cylinders.
X because there is little dispersion _{# 1}It is sufficient to set = 1. like this
In addition, the amount can be reduced for cylinders other than the cylinder that has abnormally burned.
With this, wasteful fuel injection can be suppressed.

(E) In the above embodiment, one cycle of combustion (combustion by asynchronous injection) was described, but oil-tight leakage diffuses into the intake system and affects the combustion of the second and third cycles. Therefore, with respect to the injection amounts of the second cycle and the third cycle, the reduction control may be performed by the same method.

[0104]

As described above in detail, according to the invention as set forth in claim 1, HC emission is reduced regardless of whether or not fuel leaks from the fuel injection valve while the internal combustion engine is stopped, and Stable startability can be secured.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), even if there is a tolerance regarding the air-fuel ratio, HC emission is reduced regardless of the presence or absence of fuel leaked from the fuel injection valve while the internal combustion engine is stopped, and stable startability is provided. Can be secured.

According to the invention described in claims 3 and 4, in addition to the effect of the invention described in claim 1, more stable combustion is achieved, and the emission is not increased. According to the invention described in claim 5, in addition to the effect of the invention described in claim 1, it is possible to avoid a large discharge of HC and deterioration of startability due to abnormal combustion due to rich.

According to the invention of claim 6, claim 5
In addition to the effect of the invention described in (1), the fuel amount can be reduced more accurately. According to the invention described in claim 7, in addition to the effect of the invention described in claim 6, it is possible to accurately grasp the evaporated fuel by dividing the storage area, and it is possible to perform highly accurate weight reduction.

According to the invention described in claim 8, in addition to the effect of the invention described in claim 5, the amount of fuel is reduced to cylinders other than the cylinder that has abnormally burned, and wasteful fuel injection can be suppressed.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of a fuel injection control device for an internal combustion engine of a first embodiment.

FIG. 2 is a flowchart for explaining the operation.

FIG. 3 is a flowchart for explaining an operation.

FIG. 4 is a flowchart for explaining the operation.

FIG. 5 is a flowchart for explaining the operation.

FIG. 6 is a flowchart for explaining the operation.

FIG. 7 is a flowchart for explaining the operation.

FIG. 8 is a time chart for explaining the operation.

FIG. 9 is a graph showing a map.

FIG. 10 is a graph showing a map.

FIG. 11 is a graph showing a map.

FIG. 12: Air-fuel ratio and H with respect to asynchronous injection pulse width
It is a graph which shows the relationship of C discharge amount.

FIG. 13 is a graph showing a map.

FIG. 14 is a graph showing the relationship between the air-fuel ratio and the HC emission amount with respect to the synchronous injection pulse width in the first cycle.

FIG. 15 is a graph showing a map of an application example of the first embodiment.

FIG. 16 is an overall schematic diagram of a fuel injection control device for an internal combustion engine of a second embodiment.

FIG. 17 is an explanatory diagram for explaining stored contents in the second embodiment.

FIG. 18 is a flow chart for explaining the operation of the second embodiment.

FIG. 19 is a flow chart for explaining the operation of the second embodiment.

FIG. 20 is a time chart for explaining the operation of the second embodiment.

FIG. 21 is a time chart for explaining the operation of the second embodiment.

FIG. 22 is a graph showing the relationship between the rotation increase and the amount of discharged HC with respect to the asynchronous injection pulse width.

FIG. 23 is a graph showing a relationship between rotation increase and HC emission amount with respect to an asynchronous injection pulse width.

FIG. 24 is a graph showing a map.

FIG. 25 is a graph showing a map.

FIG. 26 is an explanatory diagram showing a storage area.

FIG. 27 is an explanatory diagram showing changes in the amount of evaporated fuel.

FIG. 28 is a graph showing a map.

FIG. 29 is an explanatory diagram showing changes in the amount of evaporated fuel.

[Explanation of symbols]

1 ... Engine as internal combustion engine, 2 ... Intake pipe, 6 ... Injector (fuel injection valve), 27 ... ECU as fuel injection control means.

Continuation of the front page (56) References Japanese Patent Laid-Open No. 6-146958 (JP, A) Japanese Patent Laid-Open No. 61-1841 (JP, A) Japanese Patent Laid-Open No. 6-229284 (JP, A) Japanese Patent Laid-Open No. 7-34928 (JP , A) JP-A-63-195356 (JP, A) Actually open 6-25527 (JP, U) Actually open 2-112947 (JP, U) Actually open 6-87656 (JP, U) Actually open 62-101047 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02D 41/06 330 F02D 41/04 330 F02D 41/22 330 F02D 45/00 345

Claims (8)

(57) [Claims] 1. A fuel injection control device for an internal combustion engine, comprising: a fuel injection valve for injecting fuel into an intake system of the internal combustion engine; and fuel injection control means for driving the fuel injection valve to control a fuel injection amount. The fuel injection control means is a rich side near a fuel amount which is a lean side misfire limit when there is no fuel leakage from the fuel injection valve when the internal combustion engine is stopped until a predetermined cycle after the start of the internal combustion engine. The fuel injection control device for an internal combustion engine, wherein the fuel injection amount of the fuel is injected from the fuel injection valve. 2. The rich-side fuel amount near the lean-side misfire limit fuel amount is the lean-side allowable maximum value of the system tolerance regarding the air-fuel ratio with respect to the lean-side misfire limit fuel amount. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel amount is shifted to the rich side only. 3. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel amount is shifted to the rich side as the cycle elapses until a predetermined cycle after the start of the internal combustion engine is started. 4. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel amount is shifted to the rich side with the progress of the intake stroke until a predetermined cycle after the start of the internal combustion engine. 5. A cylinder that abnormally burns due to richness is detected and the cylinder that abnormally burns is stored until a predetermined combustion cycle after the start of the internal combustion engine is started, and the cylinder that abnormally burned is stored, and the fuel amount of the cylinder is reduced from the next start of the internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1, wherein 6. The stored contents are cylinders that have abnormally burned,
6. A correction coefficient for reducing the weight of the cylinder.
A fuel injection control device for an internal combustion engine according to item 1. 7. The storage area is divided by the temperature state of the internal combustion engine when the internal combustion engine is stopped and the time from the stop of the internal combustion engine to the start of the internal combustion engine or an element corresponding thereto. 7. A fuel injection control device for an internal combustion engine according to item 6. 8. The fuel injection control device for an internal combustion engine according to claim 5, wherein the fuel amount is reduced also in cylinders other than the cylinder in which the abnormal combustion has occurred.