JP2003148203A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preferably restrain a temperature rise in a catalyst device attributable to an injection amount increase correction upon returning from an over revolution fuel cut. SOLUTION: This fuel injection control device carries out a fuel increasing amount correction for restraining the temperature rise in the catalyst device 27 at fuel injection, and over revolution fuel cut control. Further, until a predetermined time elapses from returning from the over revolution fuel cut control, the fuel injection is carried out while inhibiting the fuel increasing amount correction. In this fuel injection device, an execution time of the over revolution fuel cut is constantly calculated based on an engine speed of the internal combustion engine 1, and the execution time of the over revolution fuel cut is set as the predetermined time.

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 a vehicle-mounted internal combustion engine, and more particularly to a fuel injection control device for executing fuel amount increase correction and fuel cut control.

[0002]

2. Description of the Related Art In recent years, in order to comply with exhaust gas regulations, many vehicles are equipped with a catalyst device having a three-way catalyst. Such a catalyst device has the highest exhaust purification efficiency when the air-fuel ratio A / F is near the stoichiometric air-fuel ratio. Therefore, the air-fuel ratio must be maintained in the vicinity of the stoichiometric air-fuel ratio in order to effectively operate the catalyst function and achieve low emission, and the air-fuel ratio control is performed in a normal internal combustion engine.

By the way, during high load operation of the internal combustion engine,
When a large amount of high-temperature exhaust gas passes through the catalyst device, the temperature of the device may rise and its heat may be deteriorated. Therefore, in general, when the operating state of the internal combustion engine becomes a state that may cause thermal deterioration of the catalyst device, the fuel injection amount is increased so that the target air-fuel ratio becomes richer than the theoretical air-fuel ratio. The fuel quantity increase correction is performed. According to this fuel increase correction, excessive fuel is decomposed at the time of combustion and the temperature of the exhaust gas is lowered by the endothermic action at the time of decomposition, so that overheating of the catalyst device can be suppressed. Further, as the fuel amount increase correction, in addition to the purpose of suppressing the overheat of the catalyst device, for example, a correction referred to as an acceleration amount increase for ensuring the output at the time of high load of the engine such as during vehicle acceleration is performed. It is also known.

On the other hand, while the fuel increase correction is performed, the engine rotation speed is set to a predetermined speed (for example, 7000 rp).
m) or more, or when the speed of the vehicle becomes a predetermined speed (for example, 180 km / h) or more, a so-called overspeed fuel cut for stopping fuel injection from the fuel injection valve is performed for engine protection and the like. Done.

Conventionally, the fuel amount increase correction for preventing the catalyst device from overheating and the over-rotation fuel cut for protecting the engine have been adopted together to keep the operating condition of the engine in good condition. Has been done.

[0006]

By the way, it cannot be denied that the above-mentioned prior art has the following concerns.

That is, while the over-rotation fuel cut is being performed, the intake air is discharged from the combustion chamber without being used for combustion and is supplied to the catalyst device through the exhaust passage. Then, if the fuel increase correction is performed immediately after the engine operating state shifts from the overspeed fuel cut execution region to the acceleration fuel increase execution region, a large amount of unburned fuel that is discharged without being burned Will react with the intake air supplied to the catalyst device at the time of over-rotation fuel cut and will burn. When such so-called afterburning occurs, the temperature of the catalyst rises sharply, which may cause thermal deterioration of the catalyst device.

Incidentally, a fuel injection control device disclosed in Japanese Patent No. 3076884 has been known as a fuel injection control device for solving the above problems. In this fuel injection amount control device,
When the operating state of the internal combustion engine shifts from the overrotation fuel cut execution region to the fuel increase amount during acceleration execution region, after that, the fuel increase correction is prohibited until a predetermined time elapses and the air existing in the catalyst device decreases. As a result, thermal deterioration of the exhaust catalyst due to the fuel increase correction is avoided.

However, in the above-mentioned prior art, for example, when the prohibition time of the fuel amount increase correction is excessively long, the start of the fuel amount increase during acceleration is delayed and the drivability is deteriorated, and overheating of the catalyst device is suppressed. The fuel amount increase correction may be delayed to cause thermal deterioration of the catalyst device. On the contrary, if the prohibition time of the fuel increase correction is too short, the fuel increase correction during acceleration or the increase correction aimed at preventing overheating of the catalyst device may cause thermal deterioration of the catalyst device due to afterburning. The present invention has been made in view of such circumstances, and an object thereof is to be able to suitably suppress the temperature rise of the catalyst device due to the injection amount increase correction when returning from the overspeed fuel cut. It is to provide a fuel injection control device for an internal combustion engine.

[0010]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. According to the first aspect of the present invention, the fuel cut is executed based on the engine speed of the internal combustion engine being equal to or higher than the predetermined speed, and the increase of the fuel injection amount is corrected until a predetermined time elapses from the return of the fuel cut. In the fuel injection control device for an on-vehicle internal combustion engine which prohibits the above-mentioned, the gist is provided with setting means for setting a predetermined time during which the fuel increase correction is prohibited based on at least one of an engine operating state and a vehicle running state.

According to the above configuration, the fuel amount increase correction is prohibited from the return of the fuel cut executed based on the engine speed of the internal combustion engine being equal to or higher than the predetermined speed until a predetermined time elapses.

It is generally known that when the engine speed is accelerated or decelerated, a phenomenon in which the vehicle vibrates in the front-rear direction, that is, so-called hiccup occurs. When such a hiccup occurs, the internal combustion engine vibrates under the influence of it, so that the engine rotation speed repeatedly rises and falls according to this vibration. Then, the fluctuation of the engine rotation speed due to such hiccup occurs very naturally even when the fuel cut is performed at the time of high engine load, whereby the fuel cut and the fuel injection are alternately repeated. A phenomenon, that is, hunting, may be caused. In the fuel injection performed during the hunting, for example, when the fuel amount increase correction for suppressing the overheating of the catalyst device is executed, the above-mentioned afterburning occurs. Then, if the hunting is continued, such afterburning will also continue to occur, resulting in overheating of the catalyst device and eventually its thermal deterioration.

The hunting cycle is basically unique to the vehicle in accordance with the hiccup cycle determined by the vehicle weight and the like, but the operating state of the internal combustion engine and the vehicle equipped with the internal combustion engine are different. It fluctuates under the influence of driving conditions. Therefore, when the fuel amount increase correction is prohibited for a predetermined time from the return of the fuel cut as in the conventional case, and the prohibition time is a predetermined constant value, the fuel amount increase correction is not always properly prohibited. In the end, the exhaust catalyst may eventually be deteriorated by heat. In this respect, in the above configuration, since the predetermined time is set based on at least one of the engine operating state and the vehicle running state,
The prohibition time is set based on each of the factors that affect the hunting cycle, such as the engine operating state and the vehicle running state. Then, since the fuel increase correction is prohibited based on the prohibition time set in this way, it is possible to preferably avoid thermal deterioration of the catalyst device and deterioration of drivability due to the fuel increase correction.

According to a second aspect of the present invention, in the fuel injection control device for the internal combustion engine according to the first aspect, the setting means constantly detects the execution time of the fuel cut based on the engine rotation speed, and the execution time is set to the execution time. The gist is to set it as the predetermined time.

According to the above configuration, the execution time of the fuel cut executed when the engine speed is equal to or higher than the predetermined speed is constantly detected based on the engine speed, and this is detected from the return of the fuel cut. Until the period corresponding to the execution time of the fuel cut has elapsed, the fuel increase correction is prohibited. By the way, since the hiccups that occur when the engine speed is accelerated or decelerated are basically repeated at regular intervals,
When the driving situation is almost constant, the hunting caused by the hiccup is also repeated at a constant cycle. That is, since the variation mode of the engine rotation speed during hunting is basically along a sine waveform, the fuel cut and fuel injection during the hunting are repeated at substantially the same cycle.

Therefore, as in the above-described configuration, the fuel amount increase correction is prohibited until the period corresponding to the execution time elapses from the return of the fuel cut, so that the next fuel cut is performed after the return of the fuel cut. The execution of the fuel amount increase correction is suppressed until the time is notified. As a result, the execution of the fuel increase correction during the hunting is also suppressed as much as possible, so that it is possible to preferably avoid the heat deterioration and the drivability deterioration of the catalyst device due to the fuel increase correction. Also, the hunting cycle may vary depending on the running state of the vehicle, etc., but with the above configuration, the execution time of the fuel cut is always detected, so if such a hunting cycle varies. However, the fuel increase correction can be properly prohibited.

According to a third aspect of the present invention, in the fuel injection control device for the internal combustion engine according to the first aspect, the setting means constantly calculates the execution time of the fuel cut based on the engine speed, and the predetermined time is set to the predetermined time. The gist is to set it longer than this execution time.

According to the above configuration, the execution time of the fuel cut executed based on the engine speed of the internal combustion engine being equal to or higher than the predetermined value is longer than the execution time of the fuel injection executed immediately after the recovery. Is corrected to. In hunting caused by hiccups, when the operating conditions during hunting do not change, the execution time of fuel cut and fuel injection is almost constant, while when the operating conditions during hunting change, The execution time of cut and fuel injection may change according to the driving situation. That is, when the operating condition changes during the hunting, a situation may occur in which the fuel injection execution time immediately after the fuel cut is longer than the fuel cut execution time. In such a case, even if the execution time of the fuel cut is adopted as the prohibition time of the fuel amount increase correction, the fuel amount increase correction may not be surely prohibited. In this respect, since the prohibition time of the fuel amount increase correction is set to be longer than the execution time of the fuel cut by adopting the above configuration, the execution time of the fuel injection immediately after that is longer than the execution time of the fuel cut. Even if a situation occurs, the fuel amount increase correction can be properly prohibited, and the heat deterioration of the catalyst device and the deterioration of drivability due to the fuel amount increase correction can be more preferably avoided.

When the prohibition time of the fuel amount increase correction is set longer than the execution time of the fuel cut in this way, the variation of the hunting cycle is obtained by an experiment or the like and based on the magnitude of the variation. It is desirable to set a prohibition time. For example, in this case,
This is set so that the greater the variation in the hunting cycle, the longer the prohibition time with respect to the fuel cut execution time. Further, in this setting, the learning value of the hunting cycle learned according to the driving situation, the traveling state of the vehicle, or the like may also be taken into consideration.

According to a fourth aspect of the present invention, in the fuel injection control device for an internal combustion engine according to the first aspect, the setting means sets a hunting cycle between the fuel cut and the fuel injection based on a vehicle shift position and a vehicle speed. The gist is to calculate and set a half cycle of the hunting cycle as the predetermined time.

According to the above configuration, the hunting cycle between the fuel cut and the fuel injection is calculated based on the shift position and the vehicle speed of the vehicle, and the half cycle of the calculated hunting cycle is calculated from the return of the fuel cut. That is, the fuel increase correction is prohibited until the period corresponding to the execution time of the fuel cut has elapsed. By the way, ・ When the shift position of the vehicle changes, the reduction ratio changes accordingly. -When the vehicle speed changes, the load from the outside such as air resistance changes accordingly. Therefore, the degree of change in the engine rotation speed also differs according to these. When the engine rotation speed is likely to change, that is, when the engine rotation speed increases or decreases at a high speed, the hunting cycle becomes short, and conversely, when the engine rotation speed hardly changes, that is, When the speed at which the engine rotation speed increases or decreases, the hunting cycle becomes longer when the speed is low. Therefore, as in the above configuration, the half cycle of the hunting cycle calculated based on the shift position and the vehicle speed of the vehicle is adopted as the prohibition time of the fuel increase correction, so that the next fuel cut is performed from the return of the fuel cut. Until then, the fuel amount increase correction is suppressed, and by extension, the fuel amount increase correction during hunting is suppressed as much as possible. For this reason, it is possible to preferably avoid thermal deterioration of the catalyst device and deterioration of drivability due to the fuel increase correction.

According to a fifth aspect of the present invention, the setting means calculates a hunting cycle between the fuel cut and the fuel injection based on a ratio between an engine speed and a vehicle speed, and a half cycle of the hunting cycle is calculated as the half cycle. The point is to set it as a predetermined time.

According to the above configuration, the hunting cycle between the fuel cut and the fuel injection is calculated based on the ratio between the engine speed of the internal combustion engine and the vehicle speed of the vehicle, and is calculated from the return of the fuel cut. The fuel amount increase correction is prohibited until a half period of the hunting period, that is, a period corresponding to the fuel cut execution time elapses. Incidentally, the so-called N / V ratio, which is the ratio between the engine speed and the vehicle speed, is usually adopted to estimate the shift position, and the N / V ratio increases as the shift position becomes lower. -The higher the shift position, the smaller the N / V ratio. It changes with such a form. Therefore, basically, the hunting cycle becomes shorter as the N / V ratio becomes a large value indicating that the engine rotation speed easily changes. The N / V ratio becomes longer as the value becomes smaller, which indicates that the engine speed is unlikely to change. Shows the tendency. Therefore, as in the above configuration, by adopting a half cycle of the hunting cycle calculated based on the ratio of the engine speed of the internal combustion engine to the vehicle speed of the vehicle as the prohibition time of the fuel increase correction, the fuel increase correction can be performed. It is properly prohibited, and the fuel amount increase correction is suppressed as much as possible from the return of the fuel cut to the next fuel cut. As a result, the execution of the fuel increase correction during the hunting is also suppressed as much as possible, so that it is possible to preferably avoid the heat deterioration and the drivability deterioration of the catalyst device due to the fuel increase correction.

The invention according to claim 6 is the invention according to claim 4 or 5.
The fuel injection control device for an internal combustion engine as described above, further comprising a first correction means for correcting the hunting cycle based on an uphill and a downhill state of the vehicle.

According to the above configuration, the hunting cycle between fuel cut and fuel injection is corrected based on the uphill and downhill states of the vehicle. By the way, even when the vehicle is in different uphill and downhill states, the load acting on the vehicle from the outside changes, and accordingly, the degree of change in the engine rotation speed also changes. Therefore, the hunting cycle is shortened depending on the above-described climbing and descending conditions: -When the vehicle is in a climbing condition in which a large external load acts on the vehicle.・ It will be longer when the vehicle is on a downhill where the load on the vehicle from the outside is small. Shows the tendency. Therefore, by correcting the hunting cycle between the fuel cut and the fuel injection based on the uphill and downhill states of the vehicle as in the above configuration, it is possible to more appropriately prohibit the fuel increase correction.

According to a seventh aspect of the present invention, there is provided a fuel injection control device for an internal combustion engine according to any of the fourth to sixth aspects,
The gist is to further include a second correction unit that corrects the hunting cycle based on the rate of change of the engine load.

According to the above arrangement, the hunting cycle between fuel cut and fuel injection is corrected based on the rate of change of the load of the internal combustion engine. By the way, if the rate of change of the load of the internal combustion engine is different, the sliding resistance of each part of the engine is changed, and accordingly, the degree of change of the engine rotational speed is also different. Therefore, the hunting cycle becomes shorter according to the rate of change of the load of the internal combustion engine: When the rate of change of the load is large, that is, when the sliding resistance or the like is large.・ If the rate of change of load is small, that is, if the sliding resistance is small, it will be long. Shows the tendency. Therefore, as in the above configuration, the hunting cycle between fuel cut and fuel injection is corrected based on the change rate of the load of the internal combustion engine, so that the fuel increase correction can be more appropriately prohibited.

The invention according to claim 8 is the fuel injection control device for an internal combustion engine according to any one of claims 1 to 7,
The gist is to further include prohibition permission means for permitting prohibition of the fuel amount increase correction only when the engine operating state is the specific operating state.

According to the above configuration, the prohibition of the fuel increase correction is permitted only when the operating state of the internal combustion engine is in the specific operating state. When hunting occurs between fuel cut and fuel injection, even if the fuel increase correction is applied to the fuel injection, such fuel increase correction does not necessarily cause thermal deterioration of the catalyst device. Therefore, even when the hunting occurs, the fuel amount increase correction may effectively prevent overheating of the catalyst device through the heat absorbing action. Therefore, as in the above configuration, the prohibition of the fuel increase correction is permitted only when the operating state of the internal combustion engine is in the specific operation state, so that the effect of preventing the catalyst device from overheating due to the fuel increase correction is effectively exhibited. Will be able to.

According to a ninth aspect of the present invention, in the fuel injection control device for the internal combustion engine according to the eighth aspect, the prohibition permission means has the fuel increase rate by the fuel increase correction as the specific operating state is less than a predetermined value. It is a gist to permit the prohibition of the fuel increase correction only at times.

According to the above configuration, the prohibition of the fuel increase correction is permitted only when the fuel increase rate by the fuel increase correction is less than the predetermined value. By the way, when the fuel cut is being executed based on the engine speed being equal to or higher than a predetermined value, the intake air is supplied to the catalyst device. However, since the amount of the intake air is limited, the intake air does not react with the intake air. There is a corresponding upper limit for fuel burn. Therefore, when unburned fuel in excess of this upper limit is discharged, unburned fuel that has not completely burned by reacting with intake air, that is, unburned fuel that has not been used for afterburning, is This will lower the exhaust temperature. Therefore, when the unburned fuel discharged from the combustion chamber becomes more than the upper limit amount, the exhaust temperature rises due to afterburning of the unburned fuel. -The temperature of the exhaust gas decreases due to unburned fuel that has not been used for afterburning. When the unburned fuel discharged from the combustion chamber exceeds a predetermined amount, the decrease in the exhaust temperature exceeds the increase in the exhaust temperature, resulting in afterburning. Even though
A phenomenon occurs such that the exhaust temperature drops. Therefore, as in the above-described configuration, the prohibition of the fuel increase correction is permitted only when the fuel increase rate by the fuel increase correction is less than the predetermined value, so that the effect of preventing overheating of the catalyst device by the fuel increase correction can be achieved. You will be able to play effectively.

According to a tenth aspect of the present invention, in the fuel injection control device for the internal combustion engine according to the eighth aspect, the prohibition permission means only corrects the fuel amount increase when the ignition timing is within a predetermined range as the specific operation state. The gist is to allow the prohibition of.

According to the above configuration, the prohibition of the fuel increase correction is permitted only when the ignition timing is within the predetermined range.
By the way, the more the ignition timing is advanced, the earlier the combustion start time of the air-fuel mixture becomes, and accordingly the place where afterburning occurs in the exhaust passage approaches the combustion chamber. -The retarded angle delays the combustion start time of the air-fuel mixture, and accordingly the place where afterburning occurs in the exhaust passage is separated from the combustion chamber. As described above, since the location of the afterburning is changed, the afterburning may occur in a place other than the catalyst device depending on the ignition timing. Therefore, even if unburned fuel is discharged immediately after the end of fuel cut, such a situation does not necessarily lead to thermal deterioration of the catalyst device.
Therefore, as in the above configuration, the prohibition of the fuel amount increase correction is permitted only when the ignition timing is within the predetermined range, so that the effect of preventing the catalyst device from overheating due to the fuel amount increase correction can be effectively obtained. Become.

According to a tenth aspect of the present invention, in the fuel injection control device for the internal combustion engine according to the eighth aspect, the prohibition permission means is set to the specific operation state, and the fuel increase rate by the fuel increase correction is less than a predetermined value. The gist is to permit the prohibition of the fuel increase correction only when the ignition timing is within a predetermined range.

According to the above configuration, the prohibition of the fuel increase correction is permitted only when the fuel increase rate by the fuel increase correction is less than the predetermined value and the ignition timing is within the predetermined range. By adopting such a configuration, the execution of the fuel injection accompanied by the fuel increase correction is appropriately permitted, so that the effect of preventing the catalyst device from overheating due to the fuel increase correction can be more effectively utilized.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS.

First, an outline of a fuel injection control device for an internal combustion engine according to the embodiment will be described with reference to FIG. Note that FIG. 1 schematically shows the overall configuration of the fuel injection control device.

As shown in FIG. 1, this system is an electronic control unit (EC) that integrally controls the internal combustion engine 1.
U) 3 is provided, and various detection data of the internal combustion engine 1 is input to the ECU 3 through the detection system 4.

Here, in the internal combustion engine 1, the cylinder 10 in which the combustion of the air-fuel mixture is carried out is the cylinder block 1.
A plurality of cylinder heads 15 are provided on the cylinder 10. An ignition plug 12 for igniting the air-fuel mixture, an intake valve 13 for intake, an exhaust valve 14 for exhaust, and the like are provided on the upper part of the cylinder 10. A piston 18, which is connected to a crankshaft 16 which is an output shaft of the internal combustion engine 1 via a connecting rod 17, is slidably accommodated in the cylinder 10. Then, the air-fuel mixture is burned in the combustion chamber 19 formed by the piston 18 and the cylinder head 15 facing each other.
The reciprocating motion of 8 is converted into a rotary motion by the connecting rod 17 and then transmitted to the crankshaft 16.

An intake passage 22 provided with an air cleaner 20 and a throttle valve 21 is connected to the combustion chamber 19, and intake air is supplied to the combustion chamber 19 through the intake passage 22. The throttle valve 21 is opened and closed by an actuator 23 such as a motor provided in the vicinity of the throttle valve 21 so that the opening of the throttle valve 21 corresponds to the depression amount of the accelerator pedal 24.

Fuel stored in a fuel tank (not shown) is supplied to the fuel injection valve 25.
In response to a signal from the CU 3, the electromagnetic valve of the fuel injection valve 25 is opened for a predetermined time, so that fuel is injected and supplied to the intake passage 22.

In this way, the mixture of fuel and intake air injected and supplied through the fuel injection valve 25 becomes the combustion chamber 19
After being supplied to the engine and compressed to a high pressure by the piston 18, combustion is performed through ignition by the ignition plug 12. The crankshaft 16 is rotated by the combustion energy generated at this time, and the exhaust gas after combustion is
After being purified by the catalyst device 27 through the exhaust passage 26 connected to the combustion chamber 19 when the exhaust valve 14 is opened,
It is discharged to the outside of the internal combustion engine 1. The catalyst device 2
No. 7 has a three-way catalyst (not shown), and its exhaust purification function is effectively exhibited only when the air-fuel ratio of the air-fuel mixture is near the stoichiometric air-fuel ratio. Therefore, in the internal combustion engine 1, the air-fuel ratio control described below is performed.

On the other hand, in such a fuel injection control device
A detection system 4 for detecting the operating state of the internal combustion engine 1 and the like.
Is a rotation speed (Ne) sensor 40, an air flow meter 4
1, accelerator sensor 42, throttle position sensor
43, oxygen (O₂) Sensor 44 _,Exhaust temperature sensor 45_,
It is composed of a vehicle speed sensor 46 and the like.

Here, the Ne sensor 40 provided in the vicinity of the crankshaft 16 detects the rotational speed of the crankshaft 16 (engine rotational speed Ne), and the air flow meter 41 provided upstream of the throttle valve 21 is
Amount of air taken into the internal combustion engine 1 from the outside (intake air amount A
r) is detected. Incidentally, in the fuel injection control for controlling the injection amount of fuel from the fuel injection valve 25, the fuel injection amount is calculated based on the engine speed Ne, the intake air amount Ar, etc., and the fuel injection valve 25 is correspondingly calculated. The valve opening time of is determined.

An accelerator sensor 42 provided near the accelerator pedal 24 detects the amount of depression of the accelerator pedal 24, and a throttle position sensor 43 provided near the throttle valve 21 opens the throttle valve 21. To detect. By the way, in the throttle control in which the actual throttle opening, which is the actual opening of the throttle valve 21, and the target throttle opening, which is the target opening, are matched, the depression amount of the accelerator pedal 24 and the engine rotation speed Ne are The target throttle opening is calculated based on the above, and the opening of the throttle valve 21 is controlled so as to match the target throttle opening.

An oxygen sensor 44 provided in the exhaust passage 26 detects the oxygen concentration contained in the exhaust gas discharged from the combustion chamber 19, and an exhaust gas temperature sensor 45 also provided in the exhaust passage 26 is provided from the combustion chamber 19. Detects the temperature of discharged exhaust.

As described above, in the internal combustion engine 1, the air-fuel ratio control is performed in order to effectively exhibit the function of the catalyst device 27. In this air-fuel ratio control, the oxygen sensor 44 detects the air-fuel ratio. It is judged whether the air-fuel mixture is rich or lean based on the oxygen concentration,
The fuel injection amount is controlled accordingly.

Further, while such air-fuel ratio control is being performed, if there is a possibility that the catalyst device 27 will be thermally deteriorated, the fuel increase correction (OT) for positively increasing the air-fuel ratio is performed.
Increase). In this OT amount increase, it is judged whether or not there is a risk of the thermal deterioration based on the exhaust gas temperature detected by the exhaust gas temperature sensor 45, and the fuel injection amount increase correction is performed accordingly. By performing such an OT amount increase, unburned fuel that is not used for combustion in the combustion chamber 19 increases, and the endothermic action of the unburned fuel increases the catalyst device 2.
The thermal deterioration of No. 7 is suppressed. As such a correction for increasing the basic fuel injection amount (calculated from the engine rotation speed Ne and the intake air amount Ar), there is an acceleration increase amount which is performed when the internal combustion engine 1 has a high load. With this acceleration-time increase, the rich air-fuel ratio (A / F = 12.5) in which the torque characteristic with respect to the air-fuel ratio shows a peak when the throttle valve 21 is largely opened and under high load, that is, when a larger torque is required. ) The fuel injection amount is increased and corrected so as to be in the vicinity.

In addition to the above-described corrections for increasing the fuel amount, so-called over-rotation fuel is used to stop the fuel injection from the fuel injection valve 25 to protect the engine when the engine speed becomes high, for example, 7,000 rpm or more. A cut is made. By the way, this overspeed fuel cut is caused by the vehicle speed sensor 46.
It is also performed when the vehicle speed of the vehicle detected by is equal to or higher than a predetermined speed.

Here, the above-mentioned air-fuel ratio control, each fuel increase correction, and over-rotation fuel cut are performed within the region defined based on the engine rotation speed Ne and the engine load shown in FIG. It should be noted that the air-fuel ratio control and the fuel increase correction may not be executed even when the engine speed Ne and the engine load are in the region to be executed, unless another condition is satisfied. On the other hand, the excessive rotation fuel cut is executed when the engine rotation speed Ne exceeds the predetermined rotation speed Nex shown in FIG.
It will be stopped if it falls below.

By the way, generally, during acceleration / deceleration of engine rotation, a transient vibration phenomenon with little damping in the vehicle longitudinal direction,
It is known that so-called hiccups occur. Since the internal combustion engine mounted on the vehicle naturally oscillates under the influence of the above-mentioned hiccup, the engine rotation speed repeatedly rises and falls in response to this vibration. The fluctuation of the engine speed due to such hiccup occurs very naturally even when the overspeed fuel cut is performed, and in this case, the overspeed fuel cut and the fuel injection are performed as shown in FIG. This causes so-called hunting, which is repeated alternately. At this time, during the overspeed fuel cut period Tfc, the intake air is not used for combustion and is discharged to the exhaust passage 26, so that the catalyst device 27 is supplied with intake air containing a large amount of oxygen. On the other hand, when the fuel increase correction is executed during the fuel injection period Tfj, a large amount of unburned fuel is supplied to the catalyst device 27 through the exhaust passage 26. When the unburned fuel and the intake air react with each other in the catalyst device 27 and afterburning occurs and the hunting continues for a certain period of time or more, the temperature of the catalyst device 27 rises and is thermally deteriorated. There is a risk. After that, the overspeed fuel cut period Tf
c and the fuel injection period Tfj, that is, time tf
The hunting period is from 1 to time tf3.

Since it is not preferable that the catalyst device 27 is thermally deteriorated and the function of purifying the exhaust gas is impaired as described above, in the present embodiment, the fuel amount increase correction prohibition process suitable for avoiding such a situation is adopted. is doing.

The fuel amount increase correction prohibition process adopted in this embodiment will be described below with reference to FIGS. 4 to 6. Note that FIG. 4 shows the processing procedure for calculating the overspeed fuel cut cycle, FIG. 5 shows the operation of the increase prohibition counter, and FIG. 6 shows the processing procedure for the determination of the counter value.

First, the overspeed fuel cut cycle calculation process will be described with reference to FIG. First, step S10
In 1, it is determined whether or not the excessive rotation fuel cut has been executed this time. If it is determined that the overspeed fuel cut has been executed this time, the process proceeds to step S102. On the other hand, if it is determined that the overspeed fuel cut has not been executed this time, the process proceeds to step S103.

Next, at step S102, a cycle calculation counter for measuring the execution time of the overspeed fuel cut is started, and this processing is once terminated. In addition, step S103
Then, it is determined whether or not the excessive rotation fuel cut has been stopped this time. If it is determined that the overspeed fuel cut is stopped this time, the process proceeds to step S104, while this time,
If it is determined that the excessive rotation fuel cut has not been stopped, this processing is temporarily terminated.

Next, in step S104, the period calculation counter is stopped, the process proceeds to step S105, the measured value (FCCNT) of the period calculation counter is substituted for the prohibition determination value TPH, and this process is once terminated.

That is, through the above-described over-rotation fuel cut cycle calculation processing (FIG. 4): The cycle calculation counter is started at the same time when the over-rotation fuel cut is started.・ The cycle calculation counter is stopped at the same time when the overspeed fuel cut is completed. By performing such a counter operation, the execution time of the overspeed fuel cut (cycle calculation counter value FCCNT) is measured, and the execution time is substituted into the prohibition determination value TPH.

The prohibition determination value TPH is a threshold time which serves as a criterion for determining whether or not to prohibit the fuel increase correction in the counter value determination process (FIG. 6) described later, and based on this, the overspeed is determined. When the elapsed time from the end of the fuel cut is greater than or equal to the prohibition determination value TPH, execution of the fuel increase correction is permitted. If the value is less than the prohibition determination value TPH, execution of the fuel increase correction is prohibited. Such processing is performed.

Next, referring to FIG. 5, the increase prohibition counter process will be described. First, in step S201, it is determined whether or not the excessive rotation fuel cut is being executed. If it is determined that the excessive rotation fuel cut is being executed, the process proceeds to step S202. On the other hand, if it is determined that the excessive rotation fuel cut is not being executed, this processing is temporarily terminated.

Next, in step S202, the counter value otpinh of the auto increment counter (increase prohibition counter) which starts at the same time as the end of the overspeed fuel cut is cleared.

That is, the increase prohibition counter processing (FIG. 5)
Through ・ Increase prohibition counter value o
Hold tpinh at "0".・ Increase prohibition counter value o after completion of over-rotation fuel cut
Start incrementing tpinh. By such counter operation, the elapsed time from the end of the overspeed fuel cut is measured. In other words, it can be said that the increase prohibition counter value otpinh corresponds to the execution period of the fuel injection executed immediately after the end of the overspeed fuel cut.

Next, the counter value judgment processing shown in FIG. 6 will be described. First, in step S301, it is determined whether or not the increase prohibition counter value otpinh is "0". If it is determined that the increase prohibition counter value otpinh is "0", this processing is temporarily terminated, while if it is determined that the increase prohibition counter value otpinh is not "0", the process proceeds to step S302.

Next, at step S302, it is judged if the increase prohibition counter value otpinh exceeds the prohibition judgment value TPH. If it is determined that the increase prohibition counter value otpinh exceeds the prohibition determination value TPH, the process proceeds to step S303, the execution of the fuel increase correction is permitted, and then the present process is temporarily terminated. On the other hand, when it is determined that the increase prohibition counter value otpinh does not exceed the prohibition determination value TPH, the process proceeds to step S304, the execution of the fuel increase correction is prohibited, and the present process is temporarily ended.

In other words, through the counter value determination process (FIG. 6), the prohibition determination value TPH (cycle calculation counter value FC)
If it is less than CNT), the execution of the fuel increase correction is prohibited, while the elapsed time from the end of the overspeed fuel cut is the execution determination time, the prohibition determination value TPH (cycle calculation counter value FC
If it is equal to or more than CNT), execution of the fuel increase correction is permitted. When the increase prohibition counter value otpinh is “0”, that is, while the overspeed fuel cut is being executed, the fuel increase correction is naturally not executed.

By the way, since the above-mentioned hiccup is basically repeated in a constant cycle, hunting caused by the hiccup is also repeated in a constant cycle when the operating condition is almost constant. Here, referring to FIG. 3 again, the over-rotation fuel cut period Tfc (time tf1 to time tf2) and the fuel injection period Tfj (time tf2 to time tf3) are substantially the same, in other words. The engine speed during hunting basically fluctuates along a sinusoidal waveform.

Therefore, through the fuel amount increase correction prohibition process performed according to the above-described procedure (FIGS. 4 to 6), (a) execution time of overspeed fuel cut (cycle calculation counter value FCCNT) (b) overspeed fuel cut Based on the elapsed time from the end (increase prohibition counter value otpinh), (c) the elapsed time from the end of overspeed fuel cut is equal to or longer than the execution time (cycle calculation counter value FCCNT ≤ increase prohibition counter value otpinh). Up to, due to the prohibition of fuel increase correction,
From time tf2 in FIG. 3, overspeed fuel cut period Tf
Until c has elapsed, the fuel amount increase correction is prohibited. Since this processing is repeated thereafter, as a result, the fuel amount increase correction during hunting is uniformly prohibited.

As a result, even if the excessive rotation fuel cut and the fuel injection are repeatedly executed, the fuel amount increase correction during the fuel injection is prohibited, so that the thermal deterioration of the catalyst device 27 due to the afterburning occurs. It will be avoided appropriately.

Next, with reference to FIG. 7, the prohibition mode of the fuel increase correction will be described in more detail. It should be noted that FIG. 7 shows the operation mode of each counter and the like ((b) to (f)) according to the variation of the engine speed (a), and the situation indicated by the one-dot chain line and the situation indicated by the solid line The driving conditions (state of climbing and descending of the vehicle, etc.) are almost constant, but different loading states of the vehicles are assumed.

First, the state shown by the alternate long and short dash line in FIG. 7 will be described. Now, if it is detected by the Ne sensor 40 (FIG. 1) that the engine rotation speed Ne exceeds the predetermined rotation speed Nex, overrotation fuel cut is executed at time t70 (FIGS. 7A and 7B). . As a result, hiccup occurs, and the engine rotation speed Ne repeats increasing and decreasing for a while after the time t70 (FIG. 7A). Further, when the engine rotation speed Ne exceeds the predetermined rotation speed Nex, counting by the cycle calculation counter is started (FIG. 7 (c)). The engine speed N
When e is lowered and it is detected at time t71 that it is lower than the predetermined rotation speed Nex, the overspeed fuel cut is stopped (FIGS. 7A and 7B). In response to this, counting by the cycle calculation counter is stopped (see FIG. 7).
(C)), counting by the increase prohibition counter and fuel injection by the fuel injection valve 25 are started (FIG. 7 (d),
(E)). Then, from the time t71, the counter value FCCNT of the cycle calculation counter (FIG. 7C), that is, until the execution time (time T7) of the overspeed fuel cut elapses (FIG. 7B), the counter value determination is performed. By the processing (FIG. 6), the fuel increase correction is prohibited (FIG. 7 (f)). In short, the fuel increase correction is prohibited during the period from time t71 to time t72 (FIG. 7 (f)). And
At the time t72, after it is detected that the engine rotation speed Ne exceeds the predetermined rotation speed Nex again, the processing from the time t70 to the time t72 is repeated until the hunting caused by the hiccup converges.

Next, it is assumed that the loading state of the vehicle is different from the one-dot chain line described above, for example, the total weight of the vehicle is relatively low due to a decrease in the number of passengers, and the counters ((( The operation modes (solid lines) of b) to (f) will be described.

Also in this case, when it is detected at time t80 that the engine speed Ne exceeds the predetermined speed Nex, the overspeed fuel cut is executed, and the engine speed Ne is repeatedly increased and decreased accordingly. 7 (a),
(B)). Incidentally, in the state shown by this solid line, the total vehicle weight is lower than in the state shown by the above-mentioned alternate long and short dash line, so that the engine rotation speed Ne is likely to rise and is difficult to fall. Therefore, the hunting period in the state of the solid line (for example, time t80 to time t82) is the hunting period in the state of the alternate long and short dash line (for example, time t70).
Up to time t72) (FIG. 7 (b),
(E)). Then, even in such a case, (A) start of counting by the cycle calculation counter accompanying execution of the overspeed fuel cut at time t80 (see FIG. 7).
(A), (c)). (B) Stop of counting by the cycle calculation counter accompanying stop of overspeed fuel cut at time t81 (see FIG. 7).
(A), (c)). (C) Counting by the increase prohibition counter accompanying stop of the excessive rotation fuel cut at time t81 and start of fuel injection by the fuel injection valve 25 (FIG. 1) (FIG. 7 (d),
(E)). (D) Prohibition of fuel increase correction from time t81 to time T8 which is the execution time of the overspeed fuel cut (FIG. 7).
(F)). Each processing (A) to (D) is performed, and such processing is repeated after time t82.

That is, according to the above-described fuel increase correction prohibiting process, even if the execution time of the overspeed fuel cut and the fuel injection fluctuates, the fuel increase correction is prohibited accordingly.

Here, it is assumed that, in the conventional fuel increase correction prohibiting process, for example, the time T7 in FIG. 7 is adopted as the fuel increase correction prohibiting time. In this case, in the state indicated by the above-mentioned alternate long and short dash line, although the fuel amount increase correction is accurately prohibited, a fixed value is adopted as the prohibition time in the conventional processing, so even in the state indicated by the above solid line. Time T7 is adopted as the prohibition time. Therefore, for example, even if the prohibition of the fuel increase correction is executed at time t81, the time T8 to the time T
During the time when 7 is subtracted, the fuel injection is performed without the fuel increase correction being prohibited. As described above, according to the conventional processing, the above-described fuel injection is performed when the fuel amount increase correction is prohibited, which may eventually lead to thermal deterioration of the catalyst device 27.

In this respect, according to the present embodiment, the time corresponding to the fluctuation of the execution time of the overspeed fuel cut is adopted as the prohibition time of the fuel amount increase correction as described above, and therefore the prohibition time is not accurate. The thermal deterioration of the catalyst device 27 due to the above can be suitably avoided.

As described in detail above, according to the fuel injection control device for the internal combustion engine of the first embodiment, the following excellent effects can be obtained. (1) Through the fuel amount increase correction prohibition process, (a) Based on the execution time of the overspeed fuel cut (cycle calculation counter value FCCNT) (b) The elapsed time from the end of the overspeed fuel cut (increase prohibition counter value otpinh) (C) The fuel increase correction is prohibited until the elapsed time from the end of the overspeed fuel cut becomes equal to or longer than the execution time (cycle calculation counter value FCCNT ≦ increase prohibition counter value otpinh).
The fuel amount increase correction is not applied to the fuel injection executed immediately after the end of the overspeed fuel cut. And
Since such processing is repeated during the hunting, as a result, the fuel amount increase correction during the hunting is uniformly prohibited. As a result, even when the overspeed fuel cut and the fuel injection are repeatedly executed, the fuel amount increase correction is prohibited at the time of fuel injection, so that thermal deterioration of the catalyst device 27 due to afterburning is avoided. You will be able to.

(2) Since the execution time of the overspeed fuel cut (the cycle calculation counter value FCCNT) is constantly calculated, the fuel increase correction can be properly prohibited even when the hunting cycle changes. become.

(Second Embodiment) Referring to FIGS. 4 to 6 and FIG. 8, focusing on the difference between the second embodiment of the present invention and the first embodiment. And explain. Since the overall configuration of the fuel injection control device for the internal combustion engine according to the present embodiment is the same as the configuration according to the first embodiment, the description thereof will be omitted.

Next, the fuel amount increase correction prohibiting process according to the present embodiment will be described with reference to FIGS. First, the overspeed fuel cut cycle calculation process will be described with reference to FIG.

The over-rotation fuel cut cycle calculation processing in this embodiment is basically the same as the over-rotation fuel cut cycle calculation processing (FIG. 4) in the first embodiment, but the above step S105 ( The processing contents of FIG. 4) are different. Since the processing other than step S105 is the same as that of the first embodiment, the description thereof will be omitted.

In step S105, the cycle calculation counter value FCCNT is multiplied by the safety factor Cf to calculate the correction counter value RFCCNT (= FCCNT · Cf), and the correction counter value RFCCNT is substituted into the prohibition determination value TPH. This process ends once.

The safety factor Cf is a value peculiar to the vehicle, which is calculated from the average of the hunting period obtained by experiments. Further, the safety factor Cf may be calculated according to a learning value learned from the hunting situation in the past driving, a traveling state of the vehicle, or the like. And in any case, the safety factor Cf is
"The execution time of the over-speed fuel cut is corrected so that the execution time of the over-speed fuel cut is equal to or longer than the execution time of the fuel injection performed immediately after that." By the way, in the present embodiment, a value (fixed value) specific to the vehicle is adopted as the safety factor Cf.

Next, the increase prohibition counter process and the counter value determination process will be described. For each of these processes, the same process as each process (FIGS. 5 and 6) in the first embodiment is performed. In addition, in step S302 of the counter value determination processing (FIG. 6) in the present embodiment, the increase prohibition counter value otpi is set in the same manner as in the first embodiment.
It is determined whether or not nh exceeds the prohibition determination value TPH. As the prohibition determination value TPH, the correction counter value RFCCNT is adopted unlike the first embodiment.

Therefore, in step S302, the increase prohibition counter value otpinh, which is the elapsed time from the end of the overspeed fuel cut, is the correction counter value RFC which is the execution time of the overspeed fuel cut corrected by the safety factor Cf.
It is determined whether or not the CNT has been exceeded.

Then, the elapsed time from the end of the overspeed fuel cut is the prohibition determination value TPH (correction counter value RFCC) which is the execution time thereof.
NT). In this case, the execution of the fuel increase correction is prohibited, while the elapsed time from the end of the overspeed fuel cut is the execution determination time, the prohibition determination value TPH (correction counter value RFCC
NT) or higher. In this case, execution of the fuel increase correction is permitted.

By the way, in hunting caused by hiccups, (d) when the operating condition during hunting does not change,
The execution times of the overspeed fuel cut and the fuel injection are almost constant. On the other hand, (e) When the driving condition during hunting changes, for example, when the vehicle is climbing or descending, the execution times of overspeed fuel cut and fuel injection change with the passage of time. . In other words, in the case of (e), the situation may occur in which the execution time of the fuel injection immediately after that is longer than the execution time of the overspeed fuel cut that is executed first.

Therefore, in the overspeed fuel cut cycle calculation process (FIG. 4), the safety ratio is set so that the overspeed fuel cut execution time (cycle calculation counter value FCCNT) becomes equal to or longer than the execution time of the fuel injection performed immediately thereafter. By correcting with Cf, even in the above case (e), the fuel increase correction is properly prohibited.

Next, with reference to FIG. 8 as well, a prohibition mode of the fuel amount increase correction associated with each of the above processes (FIGS. 4 to 6) will be described. 8 shows the engine speed Ne (see FIG.
Each counter and the like due to the fluctuation of (a)) (Fig. 8 (b)-
The operation mode of (f)) is shown. Further, FIG. 8 assumes a case where the vehicle is in a downhill state. In this case, the over-rotation fuel cut (see FIG. 8 (b)) is accompanied by a change in the engine speed Ne (see FIG. 8 (a)). ) And fuel injection (Fig. 8 (e))
The execution time of changes. Therefore, in the first embodiment, the overrotation fuel cut and fuel injection execution time during hunting (time T7 or time T in FIG. 7) is executed.
8) is constant, the execution times (time T101 to T104) are different in the present embodiment.

If it is now detected by the Ne sensor 40 (FIG. 1) that the engine rotation speed Ne exceeds the predetermined rotation speed Nex, overrotation fuel cut is started at time t100 (FIGS. 8 (a), (a). b)). As a result, hiccup occurs, and the engine speed Ne repeatedly increases and decreases for a while after the time t100 (FIG. 8A). By the way, when the vehicle is in a downhill state, the engine rotation speed Ne easily rises and is hard to fall, so that the hunting cycle becomes longer with time. Since the operating condition shown in FIG. 8 is also in accordance with this, the execution time of the fuel injection performed immediately after that (time T102) is shorter than the execution time of the first overspeed fuel cut (time T101). Takes a long time (Fig. 8
(B), (e)).

Even in such a case, (A ') the counting by the cycle calculation counter is started with the execution of the overspeed fuel cut at time t100 (FIGS. 8A and 8C). (B ′) Stop of counting by the cycle calculation counter accompanying stop of overspeed fuel cut at time t101 (FIGS. 8A and 8C), and cycle calculation counter value FCCN
T is corrected by the safety factor Cf, and the correction counter value RFCC
Calculate NT. (C ′) Counting by the increase prohibition counter accompanying stop of the excessive rotation fuel cut at time t101 and start of fuel injection by the fuel injection valve 25 (FIG. 1) (FIG. 8 (d),
(E)). (D ') Correction counter value RFCCNT from time t101
The fuel quantity increase correction is prohibited until the time corresponding to (e.g., substantially until time t102) elapses (FIG. 8 (f)). Each processing (A ') to (D') is performed at time t1.
Such processing is repeated after 02.

As a result, even if the cycle of the vehicle fluctuates during hunting due to changes in the uphill and downhill conditions of the vehicle, the fuel increase correction can be properly prohibited. As described in detail above, according to the device according to the second embodiment, in addition to the effects (1) and (2) according to the first embodiment described above, The effect will be obtained.

(3) Through the overspeed fuel cut cycle calculation process (FIG. 4), it is safe that the overspeed fuel cut execution time (cycle calculation counter value FCCNT) becomes equal to or longer than the execution time of the fuel injection performed immediately thereafter. It is corrected by the rate Cf. As a result, (e) when the driving condition during hunting changes, for example, when the vehicle is climbing or descending, the execution times of overspeed fuel cut and fuel injection change with the passage of time. Even in such a case, the fuel amount increase correction is properly prohibited, and the catalyst device 27 caused by the fuel amount increase correction is properly prohibited.
It becomes possible to more appropriately avoid the heat deterioration and the like.

The first and second embodiments described above are
It is also possible to implement them by appropriately modifying them, for example. In the first embodiment, the execution time of the overspeed fuel cut (cycle calculation counter value FCCNT) is constantly calculated, and (c) the elapsed time from the end of the overspeed fuel cut is equal to or longer than the execution time (cycle). Until the calculation counter value FCCNT ≦ the increase prohibition counter value otpinh), the fuel increase correction is prohibited. However, for example, the hunting cycle of the overspeed fuel cut and the fuel injection is calculated, and the overspeed fuel cut performed after the calculation. The fuel increase correction may be prohibited from the start of the fuel injection until the time corresponding to the hunting period.

Alternatively, the fuel increase correction may be prohibited for a period corresponding to a half cycle of the hunting cycle from the end of the overspeed fuel cut.・ Or, the execution time of fuel injection is calculated, and from the end of the overspeed fuel cut to the time corresponding to the execution time,
The fuel increase correction may be prohibited. In short, regarding the fuel injection performed immediately after the end of the overspeed fuel cut,
It is sufficient that the fuel amount increase correction is not executed until the next overspeed fuel cut is performed, and the prohibition method can be changed as appropriate.

In the second embodiment, the safety factor Cf
A value specific to the vehicle is adopted as, for example, a learning value learned from the hunting situation in the driving history,
Alternatively, a value calculated based on the running state of the vehicle or the like can be adopted. In short, the safety factor Cf is set so that the execution time (cycle calculation counter value FCCNT) of the overspeed fuel cut corrected by the safety factor Cf is equal to or longer than the execution time of the fuel injection performed immediately thereafter. The calculation method can be changed as appropriate.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIGS. 1 and 9 to 13 mainly on the difference from the first embodiment. And explain.

First, an outline of a fuel injection control device for an internal combustion engine according to the present embodiment will be described with reference to FIG. An unillustrated transmission (transmission) mounted on a vehicle can select the gear ratio in five stages from a low gear having a maximum gear ratio to a top gear having a minimum gear ratio. Along with this, a reverse gear can be selected to move the vehicle backward. The selection of each of these gear ratios is performed by the driver operating the shift lever 50.

Further, as the detection system 4 in the present embodiment, a shift position sensor 51, an uphill / downhill sensor 52, etc. for detecting the driving state of the vehicle are provided.
Here, the shift position sensor 51 is provided near the shift lever 50, and at the same time, the shift lever 5 is provided.
The shift position Sp of 0 is detected. An uphill / downhill sensor 52 provided at an appropriate position of the vehicle detects the uphill / downhill state (inclination) UD of the vehicle. Then, each of these detection data is input to the ECU 3 and used in the fuel increase correction inhibition process described below.

Next, the fuel increase correction prohibition process will be described with reference to FIGS. 9 to 13. It should be noted that FIG. 9 shows the procedure for calculating the prohibited time, and FIG. 12 shows the procedure for determining the fuel increase rate and the ignition timing. Further, FIG. 10 is a calculation map showing the relationship between the shift position and vehicle speed and the hunting cycle TC, and FIG. 11 is a calculation map showing the relationship between the ascending / descending slope state and the correction coefficient R. Further, FIG. 13 is a two-dimensional map showing a region in which the fuel increase correction is prohibited in each of the operation regions divided by the ignition timing and the fuel increase rate.

First, the prohibition time calculation process shown in FIG. 9 will be described. First, in step S401, the shift position Sp by the shift position sensor 51 and the vehicle speed Sd by the vehicle speed sensor 46 are read, and the process proceeds to step S402.

Next, in step S402, the shift position S
From the hunting cycle calculation map (FIG. 10) that is a two-dimensional map of p and the vehicle speed Sd, the hunting cycle TC in the current vehicle traveling state is calculated, and the hunting cycle T is calculated.
The basic prohibition time TPHB corresponding to the half cycle of C is calculated, and the process proceeds to step S403. The basic prohibition time TPHB basically corresponds to the execution time of the overspeed fuel cut in the first and second embodiments.

Next, in step S403, the uphill / downhill state UD of the vehicle is read by the uphill / downhill sensor 52, the process proceeds to step S404, and correction is performed from the correction coefficient calculation map (FIG. 11) which is a one-dimensional map of the uphill / downhill state UD. The coefficient R is calculated, and the process proceeds to step S405.

Next, in step S405, the basic prohibition time TPHB is multiplied by the correction coefficient R to correct it, and this is calculated as the final prohibition time TPHL (= TPHB.R). Then, the process proceeds to step S406. It should be noted that the final prohibition time TPHL finally corresponds to the execution time of the overspeed fuel cut in the first and second embodiments.

Then, in step S406, the final prohibition time TPHL is substituted into the prohibition determination value TPH, and this processing is once terminated. Note that the prohibition determination value TPH is a threshold value that is a reference for determining whether or not to prohibit the fuel increase correction in the counter value determination processing (FIG. 6) described later, as in the first and second embodiments. It's time.

That is, the basic prohibition time TPHB corresponding to a half cycle of the hunting cycle TC calculated based on the shift position Sp and the vehicle speed Sd through the prohibition time calculation process (FIG. 9) is the vehicle uphill / downhill state UD. The final prohibition time TPHL, which is the corrected basic prohibition time TPHB, is substituted into the prohibition determination value TPH.

By the way, when the shift position Sp changes, the reduction ratio changes accordingly. When the vehicle speed Sd changes, the load from the outside such as the air resistance changes accordingly, so that the engine rotation speed changes accordingly. The degree of change in the speed Ne is also different. When the engine rotation speed Ne easily changes, that is, when the engine rotation speed Ne rises and falls rapidly, the hunting cycle TC becomes short, and conversely, the engine rotation speed Ne hardly changes. Case, that is, the engine speed N
When the speed at which e rises and falls is small, the hunting period TC becomes long.

Therefore, the hunting cycle TC basically depends on the shift position Sp and the vehicle speed Sd: the shift position Sp becomes shorter as the shift ratio becomes larger on the lower shift side. The vehicle speed Sd tends to become longer as the load shifts to a smaller value, and the vehicle speed Sd becomes shorter as the external load becomes higher. The vehicle speed Sd becomes longer as the load from the outside becomes lower.

That is, each hunting cycle (TC11 to TC5) shown in the above hunting cycle calculation map (FIG. 10).
In 5), the hunting cycle TC15 is basically the shortest cycle, and the cycle becomes longer toward the hunting cycle TC51 side. However, the hunting cycle TC close to the resonance point of the vehicle does not always show such a tendency because the cycle rapidly changes. In the hunting cycle calculation map (FIG. 10), the hunting cycle TC is set in consideration of the cycle fluctuation due to the resonance of the vehicle.

On the other hand, even when the uphill / downhill state UD of the vehicle is different, the load from the outside changes, and accordingly, the degree of change of the engine rotation speed Ne also changes. Therefore, the hunting cycle TC becomes shorter depending on the uphill / downhill state UD when the vehicle is in an uphill state where the external load acting on the vehicle is large, and is longer when the vehicle is in the downhill state where the external load acting on the vehicle is small. Shows a tendency to become.

That is, the correction coefficient calculation map (FIG. 11)
Each correction coefficient R shown in 1 has a value Rn of 1.
The value is 0, and a value smaller than this is set at the time of a steep slope, and a larger value is set at the time of a steep slope (Ru <Rn
(= 1.0) <Rd).

As described above, in the prohibition time calculation process (FIG. 9), (e) the shift position S affecting the hunting period TC.
The basic prohibition time TPHB is calculated based on p and the vehicle speed Sd. (g) The basic prohibition time TPHB is corrected based on the uphill / downhill state UD of the vehicle, so that the counter value determination process shown in FIG. In FIG. 12), the fuel amount increase correction is more appropriately prohibited.

Next, the counter value judgment processing shown in FIG. 6 will be described. It should be noted that in the counter value determination processing performed in the present embodiment, as shown below between steps S302 and S304 of the counter value determination processing (FIG. 6) performed in the first embodiment. A process (FIG. 12) for determining that the vehicle is in a specific operating state based on the fuel increase rate and the ignition timing is executed.

Here, the specific operation state determination processing will be described with reference to FIG. First, in S310, the fuel increase rate Frt by the fuel increase correction is determined to be the judgment fuel increase rate F
It is determined whether it is less than rtJ. Fuel increase rate Fr
When it is determined that t is less than the determined fuel increase rate FrtJ, the process proceeds to S311, while when it is determined that the fuel increase rate Frt is not less than the determined fuel increase rate FrtJ, the process proceeds to S303 (FIG. 6). .

Next, at S311, it is determined whether or not the ignition timing AOP is on the retard side with respect to the advance side determination timing HAOP and is on the advance side with respect to the retard side determination timing LAOP. When it is determined that the ignition timing AOP is on the retard side of the advance side determination timing HAOP and is on the advance side of the retard side determination timing LAOP, that is, when it is determined that it is within the predetermined range. If it is determined that the ignition timing AOP is out of the predetermined range, the process proceeds to S304 (FIG. 6), and the process proceeds to S303 (FIG. 6).

After step S303, the first
Counter value determination processing performed in the embodiment of FIG. 6 (FIG. 6)
Processing similar to is performed. That is, this determination process (see FIG.
Through (2), (h) the fuel increase rate Frt is less than the judgment fuel increase rate FrtJ (re) the ignition timing AOP is within the predetermined range determined by the advance side judgment timing HAOP and the retard side judgment timing LAOP. It is determined whether or not is satisfied.

By the way, as described above, when the over-rotation fuel cut is being executed, the intake air is supplied to the catalyst device 27, and the intake air that can be used for the combustion of the fuel exists near the catalyst device 27. However, since the amount is limited, the unburned fuel that reacts with the intake air also has an upper limit amount accordingly. Therefore, when the unburned fuel of the upper limit amount or more is discharged, the unburned fuel that has not burned due to the afterburning has its endothermic action to lower the exhaust temperature. For this reason, when the unburned fuel discharged from the combustion chamber 19 becomes more than the upper limit amount, the exhaust temperature rises due to (nu) afterburning of unburned air and unburned fuel (le) combustion due to afterburning. Two factors, such as the decrease in exhaust temperature due to unburned fuel, influences the exhaust temperature, and when the unburned fuel discharged from the combustion chamber 19 exceeds a predetermined amount, the exhaust temperature of The amount of decrease exceeds the amount of increase shown in (v) above, and as a result, a phenomenon occurs in which the exhaust gas temperature decreases, despite the occurrence of afterburning.

The above-mentioned judged fuel increase rate FrtJ is for judging whether or not such a situation occurs. When the fuel increase rate Frt is equal to or higher than this judged fuel increase rate FrtJ, afterburning occurs. However, the exhaust temperature will eventually decrease.

On the other hand, as the ignition timing AOP is advanced, the combustion start time of the air-fuel mixture becomes shorter, and accordingly, the place where afterburning occurs in the exhaust passage 26 approaches the combustion chamber 19. The retarded angle delays the combustion start time of the air-fuel mixture, and accordingly, the place where the afterburning occurs in the exhaust passage 26 is separated from the combustion chamber 19. In this way, since the location of the afterburning changes, the afterburning may occur at a location other than the catalyst device 27 depending on the ignition timing AOP. Therefore, even if the unburned fuel is discharged to the exhaust passage 26 by executing the fuel increase correction immediately after the overspeed fuel cut ends, such a situation does not necessarily lead to the thermal deterioration of the catalyst device 27. Does not mean

Then, the threshold timing of the ignition timing AOP, which indicates whether or not such a situation occurs, is the advance side determination timing HAOP.
And the retard side determination timing LAOP, and when the ignition timing AOP is in a specific operating state outside the predetermined range determined by these determination timings LAOP, HAOP, it is estimated that afterburning occurs at a place other than the catalyst device 27. be able to.

Therefore, in the counter value determination processing (FIG. 6) in the present embodiment, by performing the determination processing (FIG. 12), (o) the increase prohibition counter value otpinh is determined in step S302 (FIG. 6). Even when it is determined that the prohibition determination value TPH is not exceeded, that is, when the elapsed time from the end of the overspeed fuel cut is less than the execution time of the overspeed fuel cut, (h) the fuel increase rate Frt However, if at least one of the conditions that the ignition timing AOP is less than the determination fuel increase rate FrtJ (i) is within a predetermined range determined by the advance side determination timing HAOP and the retard side determination timing LAOP, that is, the fuel is Even if the unburned fuel is discharged from the combustion chamber 19 by performing the fuel injection with the increase correction, the catalyst device 27 caused by the unburned fuel is discharged. If there is no possibility of thermal degradation is to allow the execution of the fuel increase correction.

As described above, by appropriately permitting the execution of the fuel injection with the fuel amount increase correction, for example, the endothermic action of the OT amount increase can be effectively utilized, so that the heat deterioration of the catalyst device 27 and the like can be further suppressed. It can be avoided appropriately.

As described in detail above, according to the apparatus according to the third embodiment, the following excellent effects can be obtained. (1) Through the fuel increase correction prohibition process, (a) Execution time of the overspeed fuel cut (final prohibition time TP
HL) (b) Based on the elapsed time from the end of the overspeed fuel cut (the increase prohibition counter value otpinh), (c) the elapsed time from the end of the overspeed fuel cut is equal to or longer than the execution time (final prohibition time TPHL Until the fuel quantity increase prohibition counter value otpinh) is reached, the fuel quantity increase correction is prohibited.
The fuel amount increase correction is not executed for the fuel injection executed immediately after the end of the overspeed fuel cut. And
Since such processing is repeated during the hunting, as a result, the fuel amount increase correction during the hunting is uniformly prohibited. As a result, even when the overspeed fuel cut and the fuel injection are repeatedly executed, the fuel injection is the normal fuel injection without the fuel increase correction,
The thermal deterioration of the catalyst device 27 due to the post combustion of the unburned fuel is prevented.

(2) Through the prohibition time calculation process (FIG. 9), the basic prohibition time TPHB corresponding to half the hunting cycle TC calculated based on the shift position Sp and the vehicle speed Sd is the vehicle uphill / downhill state UD. The final inhibition time TPHL, which is the corrected basic inhibition time TPHB, is adopted as the inhibition determination value TPH. Thus, the shift position S that affects the hunting cycle TC
The basic prohibition time TPHB is calculated based on p and the vehicle speed Sd, and the basic prohibition time TPHB is corrected based on the uphill / downhill state UD of the vehicle, whereby the fuel increase correction can be more appropriately prohibited. Like

(3) Even if it is determined through the process of determining the fuel increase rate and the ignition timing (FIG. 12) that the elapsed time from the end of the overspeed fuel cut is shorter than the fuel injection execution period, (H) At least one of the conditions that the fuel increase rate Frt is less than the determined fuel increase rate FrtJ (re) the ignition timing AOP is within a predetermined range determined by the advance side determination timing HAOP and the retard side determination timing LAOP. Is not satisfied, that is, if unburned fuel is discharged from the combustion chamber 19 by executing the fuel injection with the fuel increase correction, there is no risk of thermal deterioration of the catalyst device 27 caused by the unburned fuel. The execution of the fuel increase correction is permitted. As a result, for example, the endothermic effect of increasing the OT and the like can be effectively utilized, so that the thermal deterioration of the catalyst device 27 and the like can be more preferably avoided.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIGS. 1 and 14 to 16 with a focus on the differences from the third embodiment. To do. The fuel injection control device for the internal combustion engine according to the present embodiment has the same configuration as that of the third embodiment, and therefore its description is omitted.

Next, the fuel amount increase correction prohibiting process will be described with reference to FIGS. 14 to 16. Note that FIG. 14 shows a processing procedure for calculating the prohibited time. Also,
FIG. 15 shows the relationship between the N / V ratio and the hunting cycle TC, FIG.
Reference numeral 6 is a calculation map showing the relationship between the load change rate Ld and the correction coefficient R.

First, the prohibition time calculation process shown in FIG. 14 will be described. First, in step S601, the N / V ratio nv (∝Ne / Sd), which is the ratio of the engine speed Ne by the Ne sensor 40 and the vehicle speed Sd by the vehicle speed sensor 46.
Is read, and the process proceeds to step S602.

Next, in step S602, the N / V ratio nv
Hunting cycle calculation map (Fig. 1)
From 5), the hunting cycle TC in the current vehicle traveling state is calculated, and the basic prohibition time TPHB corresponding to half the hunting cycle TC is calculated.

Next, in step S603, the intake air amount A
The load change rate Ld calculated by r or the like is read, and the process proceeds to step S604 to calculate the correction coefficient R from the correction coefficient calculation map (FIG. 16) which is a one-dimensional map of the load change rate Ld.

Next, in step S605, the basic prohibition time TPHB is multiplied by the correction coefficient R for correction, and the corrected value is calculated as the final prohibition time TPHL. Then, in step S606, the final prohibition time TPHL is substituted into the prohibition determination value TPH, and the present processing is temporarily ended. Note that the prohibition determination value TPH is a threshold value that is a reference for determining whether or not to prohibit the fuel increase correction in the counter value determination processing (FIG. 6) described later, as in the first and second embodiments. It's time.

That is, through the prohibition time calculation process (FIG. 9), the basic prohibition time TPHB corresponding to half the hunting cycle TC calculated based on the N / V ratio nv.
Is corrected according to the load change rate Ld, and the final prohibition time TPHL, which is the corrected basic prohibition time TPHB, is substituted into the prohibition determination value TPH.

The N / V ratio nv is adopted for estimating the shift position Sp. The N / V ratio nv increases as the shift position Sp is on the lower shift side. The shift position Sp is higher shift. The N / V ratio nv decreases as the position is closer to the side.

Therefore, the hunting cycle TC is basically: ・ The N / V ratio nv becomes shorter as the value becomes larger, which indicates that the engine speed Ne is more likely to change. ・ The N / V ratio nv becomes The tendency is such that the engine rotation speed Ne becomes longer as the value becomes larger, which indicates that the engine rotation speed Ne is less likely to change.

That is, the correction coefficient calculation map (FIG. 15)
The hunting cycle TC shown in (1) is set longer as the N / V ratio nv is smaller, and is set shorter as the N / V ratio nv is larger (TCs> TCb).

On the other hand, when the load change rate Ld of the internal combustion engine 1 is different, the sliding resistance of each part of the engine is changed, and accordingly, the degree of change of the engine rotation speed Ne is also different. Therefore, the hunting cycle TC is shortened in accordance with the load change rate Ld: When the load change rate Ld is large, that is, when the sliding resistance is large, the load change rate Ld is small, that is, the sliding resistance. The change mode is such that it becomes long when is small.

That is, the correction coefficient calculation map (FIG. 16)
Each correction coefficient R shown in is the correction coefficient Rm of the reference change rate.
If the rate of change Ld of the load is smaller than (1.0), a value less than 1.0 is set, and the rate of change Ld is the same.
Is larger than this, a value larger than 1.0 is set (Rs <Rm (= 1.0) <Rb).

Then, the prohibition time calculation process (FIG. 14)
The counter value determination process (FIGS. 6 and 12) is performed based on the prohibition determination value TPH calculated through. In addition,
The counter value determination processing in this embodiment is performed by the third
Since the processing is the same as the processing (FIGS. 6 and 12) in the above embodiment, the description thereof will be omitted.

As described above, in the prohibition time calculation process, (wa) the basic prohibition time TPHB is calculated based on the N / V ratio nv which affects the hunting cycle. (F) The change rate of the load of the internal combustion engine 1. By correcting the basic prohibition time TPHB based on Ld, the counter value determination process (see FIGS. 6 and 1) is performed.
In 2), the fuel quantity increase correction is more appropriately prohibited.

From the N / V ratio nv to the hunting period T
Since C is calculated, in a vehicle in which the N / V ratio nv is calculated in response to another processing request, for example, 2 as in the hunting cycle calculation map in the third embodiment.
Since it is not necessary to store the dimensional map in the ECU 3, the storage capacity can be reduced.

Since the hunting cycle TC is corrected on the basis of the load change rate Ld of the internal combustion engine 1, for example,
Even if the uphill / downhill sensor 52 and the like in the third embodiment are not newly provided, the accuracy of the prohibition determination value TPH can be improved, and the cost increase of the vehicle can be appropriately suppressed.

As described in detail above, according to the device of the fourth embodiment, in addition to the effects (1) and (3) of the third embodiment, The effects listed can be obtained.

(4) Through the prohibition time calculation process (FIG. 9), the basic prohibition time TPHB corresponding to half the hunting cycle TC calculated based on the N / V ratio nv is
The final inhibition time TPHL, which is the corrected basic inhibition time TPHB after the correction, is adopted as the inhibition determination value TPH. Thus, the basic prohibition time TPHB is calculated based on the N / V ratio nv that affects the hunting cycle TC, and the basic prohibition time TPHB is corrected based on the load change rate Ld of the internal combustion engine 1. This makes it possible to more appropriately prohibit the fuel increase correction.

(5) N / V ratio nv to hunting period T
Since C is calculated, in a vehicle in which the N / V ratio nv is calculated in response to another processing request, for example, 2 as in the hunting cycle calculation map in the third embodiment.
Since it is not necessary to store the dimensional map in the ECU 3, the storage capacity can be reduced.

(6) Since the hunting period TC is corrected based on the load change rate Ld of the internal combustion engine 1, for example,
Even if the uphill / downhill sensor 52 and the like in the third embodiment are not newly provided, the accuracy of the prohibition determination value TPH can be improved, and the cost increase of the vehicle can be appropriately suppressed.

The third and fourth embodiments described above are
It is also possible to implement them by appropriately modifying them, for example. -Correction of the basic prohibition time TPHB based on the uphill / downhill condition UD performed in the third embodiment and correction of the basic prohibition time TPHB based on the load change rate Ld performed in the fourth embodiment. It is good also as a structure which performs together.

As a method of correcting the basic prohibition time TPHB, (i) in the third embodiment, the correction is made based on the uphill / downhill state (tilt state) UD by the uphill / downhill sensor 52 (the fourth). In the embodiment, the correction is made based on the rate of change Ld of the load of the internal combustion engine 1, but the basic prohibition time TPHB may be corrected based on other than (i) or (ii). For example, in a vehicle in which vehicle height control is performed to control vehicle height variation due to the number of passengers in the vehicle, the vehicle height variation of the vehicle is detected based on the signal of the vehicle height sensor used for this, and the detected value is detected. It is also possible to correct the basic prohibition time TPHB according to the above. In short, it is sufficient that the basic prohibition time TPHB is corrected based on the factors that affect the vibration characteristics of the vehicle, and the correction method is not limited to the one exemplified in the third and fourth embodiments. It can be changed appropriately.

It is also possible to correct the basic prohibition time TPHB based on the vehicle height variation of the vehicle by such a vehicle height sensor together with the corrections of the above (i) and (ro). In this case, Even more appropriately, the fuel increase correction is prohibited. As a method of calculating the basic prohibition time TPHB, () is, in the third embodiment, a hunting cycle TC based on a two-dimensional map of the shift position Sp and the vehicle speed Sd.
To calculate. (In the above), in the fourth embodiment, the hunting cycle TC is calculated based on the one-dimensional map of the N / V ratio nv. However, the monitoring target that is the basis of the calculation of the hunting cycle TC is not limited to these (or) and (). In short, any factor may be used as long as it is a factor that changes in correlation with the hunting cycle TC, and the monitoring target or the like on which the calculation is based can be appropriately changed.

Further, each of the above maps can be appropriately changed according to the data obtained by the experiment or the engine operating condition. In each of the above-described embodiments, (h) the determination process for the fuel increase rate Frt is less than the determination fuel increase rate FrtJ (step S310), and (i) the ignition timing AOP is the advance side determination timing HAOP and the retard angle. Although the determination processing (step S311) is performed for the predetermined range determined by the side determination timing LAOP, each of these determinations may not be performed, or only one of them may be performed.

Further, the order of making the judgments in the above steps S310 and S311 may be either first, and it is not necessary to make these judgments successively. -Also, when the above (h) and (ri) are satisfied, the prohibition of the fuel increase correction is permitted, but when either of the above (h) and (li) is satisfied, the same prohibition is permitted. May be allowed.

If it is possible to determine whether or not there is a risk of thermal deterioration of the catalyst device 27 due to the fuel increase correction, the place where each of the above determinations (steps S310 and S311) is performed is the counter value determination processing. It can be changed to any position in (FIG. 6). For example, step S302 in FIG.
Each judgment may be made before.

In the counter value determination process (FIG. 6), the determination in step S302 is omitted, and the execution of the fuel increase correction is prohibited or permitted based on the determinations (h) and (d) above. It is also possible to do so.

The fuel increase rate Frt, the advance side determination timing HAOP, and the retard side determination timing LAOP may be corrected based on the operating state of the internal combustion engine 1 or the running state of the vehicle.

The fuel increase rate Frt is the monitoring target that is the basis for determining whether or not to prohibit the fuel increase correction.
And the ignition timing AOP is not limited to
The above determination may be performed by monitoring the exhaust temperature by the exhaust temperature sensor 45. In short, it suffices to be able to determine whether or not there is a risk of thermal deterioration of the catalyst device 27 due to the fuel increase correction, and the monitoring target that is the basis of the determination can be changed as appropriate.

Other elements that can be changed commonly in the above-mentioned respective embodiments are as follows. -Safety factor Cf adopted in the second embodiment
Can be calculated according to the uphill / downhill state UD by the uphill / downhill sensor 52 employed in the third embodiment.

At least one of the determination processes of steps S310 and S311 performed in the third and fourth embodiments can be adopted in the first and second embodiments.

In each of the above-mentioned embodiments, the execution time of the overspeed fuel cut or the hunting period is calculated, and the prohibition time of the fuel increase correction is set based on the calculated execution time, but the prohibition time is set by each execution. It is not limited to the method illustrated in the form. In short, it suffices that the prohibition time is set based on the operating state of the internal combustion engine 1 and the traveling state of the vehicle, and the monitoring target for that purpose can be changed as appropriate. Also,
The configuration of the internal combustion engine 1 is not limited to the configuration illustrated in each of the above embodiments, and any configuration can be adopted.
In short, the present invention can be applied to any internal combustion engine of a vehicle in which a situation in which overrotation fuel cut and fuel injection are alternately repeated due to hiccups or the like is applied, and even in such a case, according to each of the above embodiments. It is possible to exert the effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram schematically showing the overall configuration of a first embodiment of a fuel injection control device for an internal combustion engine according to the present invention.

FIG. 2 is a diagram showing an execution area of each control performed in the embodiment.

FIG. 3 is a diagram showing a variation mode of over-rotation fuel cut and fuel injection.

FIG. 4 is a flowchart showing an overspeed fuel cut cycle calculation process performed in the same embodiment.

FIG. 5 is a flowchart showing an increase prohibition counter process performed in the same embodiment.

FIG. 6 is a flowchart showing counter value determination processing performed in the same embodiment.

FIG. 7 is a timing chart showing a mode at the time when the engine speed changes in the vicinity of the overspeed fuel cut rotation speed in the same embodiment.

FIG. 8 is a timing chart showing a mode at the time of engine speed variation in the vicinity of an overspeed fuel cut rotation speed in the second embodiment of the internal combustion engine fuel injection control apparatus according to the present invention.

FIG. 9 is a flowchart showing a prohibition time calculation process performed in the third embodiment of the fuel injection control device for the internal combustion engine according to the present invention.

FIG. 10 is a two-dimensional map of shift positions and vehicle speeds used in the prohibition time calculation process performed in the same embodiment.

FIG. 11 is a one-dimensional map of an uphill / downhill state used in the prohibition time calculation processing performed in the same embodiment.

FIG. 12 is a flowchart showing a process for determining a fuel increase rate and an ignition timing, which is performed in the same embodiment.

FIG. 13 is a two-dimensional map of the fuel increase rate and the ignition timing used in the prohibition determination process performed in the same embodiment.

FIG. 14 is a flowchart showing a prohibition time out process performed in the fourth embodiment of the fuel injection control device for the internal combustion engine according to the present invention.

FIG. 15 is a one-dimensional map of the N / V ratio used in the inhibition time calculation process performed in the same embodiment.

FIG. 16 is a one-dimensional map of the load change rate used in the prohibition time calculation processing performed in the same embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 3 ... Electronic control unit (ECU), 4 ... Detection system, 10 ... Cylinder, 11 ... Cylinder block, 12 ...
Ignition plug, 13 ... intake valve, 14 ... exhaust valve,
15 ... Cylinder head, 16 ... Crank shaft, 17
... connecting rod, 18 ... piston, 19 ... combustion chamber, 20 ... air cleaner, 21 ... throttle valve, 2
2 ... Intake passage, 23 ... Actuator, 24 ... Accelerator pedal, 25 ... Fuel injection valve, 26 ... Exhaust passage, 27 ... Catalyst device, 40 ... Rotational speed (Ne) sensor, 41 ... Air flow meter, 42 ... Accelerator sensor, 43 ... Throttle position sensor, 44 ... Oxygen (O ₂ ) sensor, 45 ...
Exhaust temperature sensor, 46 ... Vehicle speed sensor, 50 ... Shift lever, 51 ... Shift position sensor, 52 ... Uphill / downhill sensor.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 362 F02D 45/00 362F 362H 362Q 364 364Z F term (reference) 3G084 BA13 CA04 DA11 EA11 EB16 EB17 FA33 3G301 HA01 JA06 KA15 KA23 KA25 KA26 KA27 KB07 MA11 ND15 ND21 NE01 NE23 PA17Z PE01Z PE09Z PF01Z

Claims (11)

[Claims] 1. A fuel cut is executed on the basis of an engine speed of an internal combustion engine being higher than a predetermined speed, and an increase correction of a fuel injection amount is prohibited until a predetermined time elapses from the return of the fuel cut. In a fuel injection control device for an on-vehicle internal combustion engine, the fuel for the on-vehicle internal combustion engine, comprising setting means for setting a predetermined time period during which the fuel increase correction is prohibited based on at least one of an engine operating state and a vehicle running state. Injection control device. 2. The fuel injection control device for an on-vehicle internal combustion engine according to claim 1, wherein the setting means always detects the execution time of the fuel cut based on the engine speed and sets the execution time as the predetermined time. 3. The fuel injection control device for an internal combustion engine according to claim 1, wherein the setting means constantly calculates the execution time of the fuel cut based on the engine speed and sets the predetermined time longer than the execution time. . 4. The setting means calculates a hunting cycle between the fuel cut and the fuel injection based on a vehicle shift position and a vehicle speed, and sets a half cycle of the hunting cycle as the predetermined time. Fuel injection control device for a vehicle-mounted internal combustion engine. 5. The setting means calculates a hunting cycle between the fuel cut and the fuel injection based on a ratio between an engine speed and a vehicle speed, and sets a half cycle of the hunting cycle as the predetermined time. Item 1. A fuel injection control device for a vehicle-mounted internal combustion engine according to item 1. 6. The fuel injection control device for a vehicle-mounted internal combustion engine according to claim 4 or 5, further comprising first correction means for correcting the hunting cycle based on an uphill and a downhill state of the vehicle. A fuel injection control device for a vehicle-mounted internal combustion engine. 7. The fuel injection control device for an on-vehicle internal combustion engine according to any one of claims 4 to 6, further comprising second correction means for correcting the hunting cycle based on a rate of change of engine load. A characteristic fuel injection control device for an on-vehicle internal combustion engine. 8. A fuel injection control device for an on-vehicle internal combustion engine according to any one of claims 1 to 7, wherein a prohibition permission means for permitting prohibition of the fuel increase correction only when the engine operating state is a specific operating state. A fuel injection control device for a vehicle-mounted internal combustion engine, further comprising: 9. The vehicle-mounted internal combustion engine according to claim 8, wherein the prohibition permission means permits prohibition of the fuel increase correction only when the fuel increase rate by the fuel increase correction is less than a predetermined value in the specific operation state. Fuel injection control device. 10. The fuel injection control device for an on-vehicle internal combustion engine according to claim 8, wherein the prohibition permission means permits the prohibition of the fuel amount increase correction only when the ignition timing is within a predetermined range as the specific operation state. 11. The prohibition permission means permits prohibition of the fuel increase correction only when the fuel increase rate by the fuel increase correction is less than a predetermined value and the ignition timing is within a predetermined range in the specific operation state. The fuel injection control device for a vehicle-mounted internal combustion engine according to claim 8.