JP2006057561A - Fuel injection amount control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To actualize advantageous effects of improving exhaust emission while properly correcting a fuel amount. <P>SOLUTION: An ECU calculates an engine required correction amount feg consisting of an after-start increased amount, a warm-up increased amount and an OTP increased amount and calculates a catalyst required correction amount fcat consisting of an acceleration/deceleration correction amount based on the accelerated/decelerated condition of a vehicle and an after-fuel-cut correction amount (S201, S202). During supplying secondary air, it calculates a secondary air supplying correction amount fsai in accordance with a secondary air flow amount and a target air/fuel ratio at this time (S204). In the case of feg≤fsai, it adds the fsai and the fcat to a base fuel amount and calculates a final fuel injection amount (S206). In the case of feg>fsai, it calculates to add the feg and the fcat to the base fuel amount and calculates the final fuel injection amount (S207). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection amount control device for an internal combustion engine, and more particularly to a technique for suitably controlling a fuel injection amount at the time of secondary air supply.

  The exhaust pipe of the internal combustion engine is provided with a catalyst device for purifying exhaust gas. In order to improve the purification efficiency of the catalyst device, the air pump is operated at the upstream side of the catalyst device when the internal combustion engine is started. Techniques for supplying secondary air have been conventionally proposed. That is, immediately after starting the internal combustion engine, secondary air supply is performed, and the secondary air supply causes oxygen in the secondary air to react with combustible components (HC, CO) in the exhaust discharged from the internal combustion engine. The exhaust temperature then rises (so-called afterburning is performed). Moreover, the oxidation reaction of the catalyst device is promoted by supplying oxygen into the catalyst device. By these actions, the catalyst device is activated early when the internal combustion engine is started. In this case, since the inside of the exhaust pipe becomes lean when the secondary air is supplied, the amount of fuel is increased in accordance with the secondary air flow rate.

  On the other hand, at the time of starting the internal combustion engine, a fuel increase such as a so-called post-start increase or warm-up increase is performed for the purpose of stabilizing the rotation of the internal combustion engine. At this time, the combustible components (HC, CO) become excessive by further increasing the amount after starting in accordance with the amount of fuel increase at the time of supplying secondary air. Moreover, since the catalyst device is not activated immediately after the internal combustion engine is started, exhaust emission is deteriorated.

  In order to solve this problem, for example, in Patent Document 1, an increase rate of the fuel supply amount is set according to the warm-up state of the internal combustion engine, and the catalyst inlet air-fuel ratio is theoretically determined during secondary air supply and idle operation. The increase rate of the fuel supply amount is set so as to be leaner than the air-fuel ratio. Further, the larger one of these two increase rates is selected to correct the fuel supply amount.

However, even if the fuel amount correction according to Patent Document 1 is performed, a problem still remains. For example, when the vehicle is accelerating or decelerating, it is conceivable that the air-fuel ratio is disturbed to the lean side or the rich side due to a change in the intake air amount or the like, and the purification efficiency of the catalyst device is thereby reduced. In this case, the above-mentioned Patent Document 1 does not disclose any measures relating to air-fuel ratio disturbance during acceleration and deceleration. Therefore, the exhaust efficiency may be deteriorated due to a decrease in the purification efficiency of the catalyst device.
JP-A-8-270484

  The main object of the present invention is to provide a fuel injection amount control device for an internal combustion engine that can optimize fuel amount correction and achieve advantageous effects such as improvement of exhaust emission.

  In the first aspect of the invention, the first correction amount calculation means calculates an increase correction amount of the fuel injection amount so as to ensure the operation performance of the internal combustion engine at the time of starting the internal combustion engine, etc., and calculates a second correction amount. The means calculates an increase correction amount of the fuel injection amount based on the secondary air flow rate when supplying the secondary air. The third correction amount calculation means calculates the fuel injection amount correction amount based on the air-fuel ratio fluctuation factor so as to maintain the purification performance of the exhaust purification device. Further, the fuel amount correction means selects the larger one of the increase correction amounts by the first and second correction amount calculation means at the time of supplying the secondary air, and the selected increase correction amount and the third correction amount. The correction amount by the correction amount calculation means is added to correct the fuel injection amount each time.

  According to the present invention, even when the increase correction amount is calculated redundantly by the first and second correction amount calculation means immediately after the start of the internal combustion engine, it is possible to suppress excessive fuel increase. . On the contrary, it is possible to prevent the originally required fuel increase from being secured and to prevent the startability of the internal combustion engine and early warm-up of the catalyst and the like from being hindered. Further, for example, when acceleration or the like is performed during the supply of secondary air, it is possible to suppress the disturbance of the air-fuel ratio and maintain the purification performance of the exhaust purification device. As described above, fuel amount correction can be optimized and advantageous effects such as improvement of exhaust emission can be realized.

  On the other hand, in order to maintain acceleration performance regardless of the type of fuel, an increase during acceleration (equivalent to the correction amount by the third correction amount calculation means) is set based on fuel with a low vaporization rate (for example, heavy gasoline). It is possible to do. In such a case, since the air-fuel ratio is controlled to the rich side in normal fuel (fuel with a normal vaporization rate), if the fuel increase corresponding to the secondary air supply and the increase during acceleration are performed simultaneously, There is a possibility that fuel will be increased. Therefore, in the invention according to claim 2, at the time of secondary air supply, either the addition value of each correction amount by the first and third correction amount calculation means or the correction amount by the third correction amount calculation means, The fuel injection amount at each time is corrected using a larger correction amount of the increase correction amount by the second correction amount calculation means.

  Thereby, even when fuel amount correction is performed based on heavy gasoline as described above, excessive fuel increase can be suppressed. Therefore, fuel amount correction can be optimized and advantageous effects such as improvement of exhaust emission can be realized.

  Here, the correction amount by the third correction amount calculating means may include an acceleration / deceleration correction amount that is implemented to suppress disturbance of the air-fuel ratio when the vehicle is accelerated / decelerated.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS An embodiment of the invention will be described below with reference to the drawings. In the present embodiment, an engine control system is constructed for an in-vehicle multi-cylinder gasoline engine that is an internal combustion engine. In the control system, an electronic control unit (hereinafter referred to as ECU) is used as a center to control the fuel injection amount. And control of ignition timing. First, an overall schematic configuration diagram of the engine control system will be described with reference to FIG.

  In the engine 10 shown in FIG. 1, the intake pipe 11 is provided with a throttle valve 14 whose opening degree is adjusted by an actuator such as a DC motor, and a throttle opening degree sensor 15 for detecting the throttle opening degree. A surge tank 16 is provided downstream of the throttle valve 14, and an intake pipe pressure sensor 17 for detecting the intake pipe pressure is provided in the surge tank 16. The surge tank 16 is connected to an intake manifold 18 that introduces air into each cylinder of the engine 10. In the intake manifold 18, an electromagnetically driven fuel injection that injects fuel near the intake port of each cylinder. A valve 19 is attached.

  An intake valve 21 and an exhaust valve 22 are respectively provided in the intake port and the exhaust port of the engine 10, and an air / fuel mixture is introduced into the combustion chamber 23 by the opening operation of the intake valve 21, and the exhaust valve 22. The exhaust after combustion is discharged to the exhaust pipe 24 by the opening operation. A spark plug 25 is attached to the cylinder head of the engine 10 for each cylinder, and a high voltage is applied to the spark plug 25 at a desired ignition timing through an ignition device (not shown) including an ignition coil. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 25, and the air-fuel mixture introduced into the combustion chamber 23 is ignited and used for combustion.

  The exhaust pipe 24 is provided with a catalyst 31 such as a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas, and the air-fuel ratio of the air-fuel mixture is detected on the upstream side of the catalyst 31 with exhaust as a detection target. An A / F sensor 32 is provided for detecting. The A / F sensor 32 includes, for example, a solid electrolyte as a sensor element, and is configured by a linear sensor that can linearly detect the oxygen concentration in the exhaust gas. Further, the cylinder block of the engine 10 includes a coolant temperature sensor 33 that detects the coolant temperature, and a crank angle sensor 34 that outputs a rectangular crank angle signal for each predetermined crank angle of the engine (for example, at a cycle of 30 ° CA). It is attached.

  As a secondary air supply system, a secondary air pipe 35 is connected upstream of the catalyst 31 in the exhaust pipe 24, and a secondary air supply means is provided upstream of the secondary air pipe 35. An air pump 36 is provided. The secondary air pump 36 is composed of, for example, a DC motor or the like, and operates by receiving power from a vehicle battery (not shown). An on-off valve 37 that opens or closes the secondary air pipe 35 is provided downstream of the secondary air pump 36. A pressure sensor 38 that detects the pressure in the secondary air pipe 35 is provided between the secondary air pump 36 and the on-off valve 37.

  The outputs of the various sensors described above are input to the ECU 40 that controls the engine. The ECU 40 is configured mainly by a microcomputer including a CPU, a ROM, a RAM, and the like, and executes various control programs stored in the ROM, so that the fuel injection amount and ignition of the fuel injection valve 19 according to the engine operating state. The ignition timing by the plug 25 is controlled. In addition, the ECU 40 supplies the secondary air by operating the secondary air pump 36 in order to activate the catalyst 31 at the time of starting the engine early.

  Next, the fuel injection amount control performed when the secondary air is supplied will be described. At the time of supplying secondary air, secondary air is supplied to the exhaust pipe 24, and fuel increase is performed according to the flow rate of the secondary air. In this case, basically, the secondary air flow rate is calculated based on the detected value (secondary air supply pressure Ps) of the pressure sensor 38 when the on-off valve 37 = open and the secondary air pump 36 = ON (actuated). However, in order to prevent a decrease in calculation accuracy due to product tolerances of the secondary air pump 36 and the pressure sensor 38, the present embodiment is based on the differential pressure between the secondary air supply pressure Ps and the reference pressure. To calculate the secondary air flow rate. For example, the closing pressure P0 as the reference pressure is detected in the state where the on-off valve 37 = closed and the secondary air pump 36 = ON, and the secondary air flow rate Qa is calculated by the following equation (1).

なお、上記（１）式において、ρは流体密度、Ｃは係数、Ａは管路断面積である。流体密度ρは温度特性を持つため、吸気温により流体密度ρを補正する構成とすることも可能である。

In the above equation (1), ρ is a fluid density, C is a coefficient, and A is a pipe cross-sectional area. Since the fluid density ρ has temperature characteristics, a configuration in which the fluid density ρ is corrected by the intake air temperature may be employed.

  Then, at the time of secondary air supply, a correction amount fsai at the time of secondary air supply is calculated according to the secondary air flow rate, and an increase correction of the fuel injection amount is performed by the fsai. The secondary air supply correction amount fsai is calculated as follows. In this case, the air-fuel ratio is represented by the excess air ratio λ, the air-fuel ratio (combustion air-fuel ratio) of the combustion gas used for combustion in the engine combustion chamber is λ1, the air-fuel ratio at the catalyst inlet is λ2, and the air is taken into the engine. Assuming that the intake air amount is ga and the secondary air flow rate is gsai, λ1 and λ2 have the relationship of the following equation (2). Both ga and gsai are mass flow rates. In particular, gsai is the mass-converted secondary air flow rate Qa described above.

空燃比λ１（空気過剰率）の逆数は燃料過剰率であり、この燃料過剰率（１／λ１）に基づいて二次エア供給時補正量ｆｓａｉが算出される。つまり、触媒入口の空燃比λ２を目標空燃比λｔｇとする場合、前記（２）式より次の（３）式が得られる。

The reciprocal of the air-fuel ratio λ1 (excess air ratio) is the excess fuel ratio, and the secondary air supply correction amount fsai is calculated based on the excess fuel ratio (1 / λ1). That is, when the air-fuel ratio λ2 at the catalyst inlet is the target air-fuel ratio λtg, the following equation (3) is obtained from the equation (2).

上記（３）式によれば、二次エア供給時における二次エア流量ｇｓａｉ、吸入空気量ｇａ及び目標空燃比λｔｇから二次エア供給時補正量ｆｓａｉが算出できる。

According to the above equation (3), the secondary air supply correction amount fsai can be calculated from the secondary air flow rate gsai, the intake air amount ga, and the target air-fuel ratio λtg when the secondary air is supplied.

  When the secondary air is supplied, a target air-fuel ratio for secondary air supply that is different from the normal time (when secondary air is not supplied) is set. For example, the fuel injection amount control is performed using a weak lean air-fuel ratio as the target air-fuel ratio. Is to be implemented. However, the target air-fuel ratio at the time of secondary air supply may be stoichiometric.

  On the other hand, for example, when the engine 10 is cold-started, an increase after start, an increase in warm-up, or the like is performed for the purpose of stabilizing the engine rotation immediately after the start. Specifically, the post-startup correction amount and the warm-up correction amount are calculated based on the water temperature at start-up, the water temperature change after start-up, and the like using a table or a mathematical expression. In addition, when there is a risk of overheating of exhaust system parts such as a catalyst during high load and high speed rotation, fuel increase is performed to increase both output torque and prevent overheating (this is generally referred to as OTP increase). ) At this time, the OTP correction amount is calculated. Each of these correction amounts is a fuel correction amount required for the purpose of ensuring engine performance. In the present embodiment, this correction amount is referred to as an “engine required correction amount feg”.

  Further, when the vehicle is accelerated or decelerated, the throttle opening increases or decreases, and the intake air amount fluctuates accordingly. In this case, the acceleration / deceleration correction amount is calculated based on a load change rate (a change amount of intake air amount or intake pipe pressure per unit time) as an air-fuel ratio fluctuation factor to suppress disturbance of the air-fuel ratio. Further, when fuel injection is resumed after fuel cut, correction after fuel cut is performed in order to quickly stabilize the air-fuel ratio. These correction amounts are correction amounts required for the purpose of maintaining the purification performance of the catalyst 31, and are referred to as “catalyst request correction amount fcat” in the present embodiment.

  Next, the secondary air supply process performed by the ECU 40 will be described. FIG. 2 is a flowchart showing the secondary air supply process. This process is executed by the ECU 40 at predetermined time intervals (for example, every 8 ms).

  In FIG. 2, in step S <b> 101, it is determined whether secondary air supply execution conditions are satisfied. For example, the execution condition is established when the engine is started and the water temperature is in a predetermined temperature range. If the execution condition is satisfied, the process proceeds to the subsequent step S102, and the secondary air supply is performed. Specifically, the on-off valve 37 is opened and the secondary air pump 36 is operated. Then, this secondary air supply is continued until, for example, the warm-up of the catalyst 31 is completed.

  If the secondary air supply execution condition is not satisfied, the process proceeds to step S103, and the secondary air supply is stopped.

  FIG. 3 is a flowchart showing the fuel injection amount control process, and this process is executed by the ECU 40 for each fuel injection of the engine 10 (every 180 ° CA for a four-cylinder engine).

  In FIG. 3, in step S201, an engine required correction amount feg including an increase after start, a warm-up increase, an OTP increase, and the like is calculated. In the subsequent step S202, a required catalyst correction amount fcat including an acceleration / deceleration correction amount based on the vehicle acceleration / deceleration state, a correction amount after fuel cut, and the like is calculated.

  Thereafter, in step S203, it is determined whether or not secondary air is currently being supplied. If the secondary air is not being supplied, the process proceeds to step S207, and the engine required correction amount feg and the catalyst required correction amount fcat are added to the base fuel amount calculated based on the engine speed and load state (for example, intake pipe pressure) each time. The final fuel injection amount is calculated by addition (fuel injection amount = base fuel amount + feg + fcat).

  If the secondary air is being supplied, the process proceeds to step S204, and the correction amount fsai at the time of secondary air supply is calculated based on the secondary air flow rate and the target air-fuel ratio at that time. Further, in step S205, the engine required correction amount feg and the secondary air supply correction amount fsai are compared. If feg ≦ fsai, the process proceeds to step S206, and the final fuel injection amount is calculated by adding the secondary air supply correction amount fsai and the required catalyst correction amount fcat to the base fuel amount (fuel injection amount = Base fuel amount + fsai + fcat). If feg> fsai, the process proceeds to step S207, and the final fuel injection amount is calculated by adding the engine required correction amount feg and the catalyst required correction amount fcat to the base fuel amount (fuel injection amount = base fuel amount). + Feg + fcat).

  FIG. 4 is a time chart showing the flow of fuel amount correction processing after engine startup. 4, (a) shows the state of secondary air supply, (b) shows the engine required correction amount feg and secondary air supply correction amount fsai, (c) shows the catalyst required correction amount fcat, and (d). Indicates the total correction amount calculated from feg, fsai, and fcat, and (e) and (f) indicate changes in the air-fuel ratio, respectively. For comparison, (f) shows the behavior of the air-fuel ratio when the secondary air supply is not performed. In FIG. 4, the secondary air supply is performed throughout the entire period shown in the figure, and the secondary air flow rate is assumed to be constant for convenience.

  As the engine 10 is started, an increase after start and an increase in warm-up are performed. As shown in (b), the engine required correction amount feg is once set as a relatively large correction amount immediately after the engine is started, and then warmed up. It is gradually reduced as the machine progresses. Further, during the period from t6 to t7, the engine request correction amount feg is temporarily increased due to the OTP increase. The correction amount fsai at the time of secondary air supply is a constant value (because the secondary air flow rate is constant). In this case, when the engine required correction amount feg and the secondary air supply correction amount fsai are compared, feg> fsai before the timing t1 and the period from t6 to t7, and feg ≦ fsai in the other periods.

  Further, as shown in (c), an acceleration request is generated in the period from t2 to t3, and a deceleration request is generated in the period from t4 to t5. In these periods, the required catalyst correction amount fcat is calculated as shown in the figure.

  As shown in (d), the total correction amount is calculated by adding the required catalyst correction amount fcat to the larger one of the engine required correction amount feg and the secondary air supply correction amount fsai. (Total correction amount = max (feg, fsai) + fcat).

  By performing the fuel amount correction with the total correction amount of (d), the combustion air-fuel ratio changes as shown in (e), and the combustion air-fuel ratio is approximately in the period excluding t1 and the period from t6 to t7. It becomes a certain rich state. Further, during the period before t1 and the period from t6 to t7, the engine is temporarily further enriched according to the engine demand.

  Incidentally, when the secondary air supply is not performed, as shown in (f), the combustion air-fuel ratio basically converges in the vicinity of the stoichiometry, and the fuel increase is performed when the fuel increase by the engine required correction amount feg is performed. It is enriched according to.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

  The larger of the engine required correction amount feg (increase correction amount by the first correction amount calculation means) and the secondary air supply correction amount fsai (increase correction amount by the second correction amount calculation means) during the secondary air supply. And the fuel injection amount is corrected by adding the selected correction amount and the required catalyst correction amount fcat (correction amount by the third correction amount calculation means). It is possible to prevent the fuel from being increased excessively, or conversely, the originally required fuel increase cannot be ensured and the engine startability and the early warm-up of the catalyst and the like are hindered. Further, when acceleration or the like is performed during the supply of the secondary air, the purification performance of the catalyst 31 can be maintained by suppressing the disturbance of the air-fuel ratio. As described above, fuel amount correction can be optimized and advantageous effects such as improvement of exhaust emission can be realized.

(Second Embodiment)
For example, the engine behavior at the time of acceleration of the vehicle changes depending on the vaporization rate of the fuel (gasoline) to be used, but generally, the acceleration correction amount is set based on the case of using relatively light gasoline. That is, on the assumption that ordinary gasoline is used, the air-fuel ratio is controlled to a target value (for example, the theoretical air-fuel ratio) by acceleration correction. In such a case, if gasoline having a smaller vaporization rate than usual (hereinafter referred to as heavy gasoline) is used, the air-fuel ratio becomes lean at the time of acceleration correction, and the engine speed decreases accordingly. Therefore, drivability deteriorates.

  Therefore, in this embodiment, in order to maintain the acceleration performance regardless of the fuel vaporization rate, the fuel correction amount is set on the assumption that heavy gasoline is used, thereby reducing the rotational speed due to the lean air-fuel ratio. To prevent. However, in this case, since the air-fuel ratio is controlled to the rich side during normal use of light gasoline, the fuel increase corresponding to the secondary air supply (fuel increase due to the correction amount fsai at the time of secondary air supply) and the increase during acceleration If the fuel increase by the catalyst requirement correction amount fcat is performed at the same time, the fuel increase may be excessively performed. Therefore, at the time of secondary air supply, the larger one of the addition value of the engine required correction amount feg and the catalyst required correction amount fcat and the secondary air supply correction amount fsai is selectively used to correct the fuel injection amount. It will be implemented.

  FIG. 5 is a flowchart showing the fuel injection amount control process in the present embodiment. This process is executed by the ECU 40 in place of FIG. In FIG. 5, steps S201 to S204 and S207 are the same as those in FIG. 3, and only steps S301 and S302 are different. Here, the difference from FIG. 3 will be mainly described.

  In FIG. 5, in steps S201 to S204, calculation of an engine required correction amount feg, a catalyst required correction amount fcat, a secondary air supply correction amount fsai, and the like are performed. In step S301, (feg + fcat) is compared with the secondary air supply correction amount fsai. If feg + fcat ≦ fsai, the process proceeds to step S302, and the final fuel injection amount is calculated by adding the secondary air supply correction amount fsai to the base fuel amount (fuel injection amount = base fuel amount + fsai). If feg + fcat> fsai, the process proceeds to step S207, and the final fuel injection amount is calculated by adding the engine required correction amount feg and the catalyst required correction amount fcat to the base fuel amount (fuel injection amount = base fuel amount). + Feg + fcat).

  FIG. 6 shows the fuel amount correction after the engine is started. As shown in FIG. 6, the total correction amount based on each correction amount (feg, fcat, fsai) at the time of secondary air supply is calculated as shown in the figure, and the fuel injection amount is corrected by this total correction amount.

  As described above, according to the second embodiment, when the secondary air supply is performed, the added value (feg + fcat) of the engine required correction amount feg and the catalyst required correction amount fcat is compared with the correction amount fsai at the time of secondary air supply. Since the fuel injection amount at each time is corrected by using, excessive fuel increase can be suppressed when each fuel increase is performed simultaneously.

  In the above embodiment, when the secondary air is supplied, the larger one of the added value (feg + fcat) of the engine required correction amount feg and the catalyst required correction amount fcat and the secondary air supply correction amount fsai is selectively used. Although the fuel injection amount was corrected, instead of this, the larger one of the required catalyst correction amount fcat and the secondary air supply correction amount fsai at the time of secondary air supply is selectively used to adjust the fuel injection amount. Correction may be performed.

  In the above embodiment, the secondary air flow rate is calculated based on the differential pressure between the secondary air supply pressure and the cutoff pressure (reference pressure), but instead, the secondary air supply pressure and the exhaust pipe interior are calculated. The secondary air flow rate may be calculated based on the exhaust pressure. For example, the secondary air flow rate is calculated based on the differential pressure between the secondary air supply pressure and the exhaust pressure. In this case, since the secondary air flow rate is calculated using not only the secondary air supply pressure but also the exhaust pressure, even if the exhaust pressure changes due to a change in the engine operating state, etc., the secondary air flow rate Can be calculated with high accuracy.

It is a block diagram which shows the outline of the engine control system in embodiment of invention. It is a flowchart which shows a secondary air supply process. It is a flowchart which shows a fuel injection amount control process. It is a time chart which shows the flow of the fuel quantity correction process after an engine start. It is a flowchart which shows the fuel injection amount control process in 2nd Embodiment. It is a time chart which shows the flow of the fuel quantity correction process after an engine start.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine as internal combustion engine, 24 ... Exhaust pipe, 31 ... Catalyst as exhaust purification device, 32 ... A / F sensor, 36 ... Secondary air pump as secondary air supply means, 40 ... First to third ECU as correction amount calculation means and fuel amount correction means.

Claims (2)

Applied to an internal combustion engine configured to supply secondary air upstream of an exhaust purification device provided in an exhaust passage of the internal combustion engine using secondary air supply means,
First correction amount calculating means for calculating an increase correction amount of the fuel injection amount so as to ensure the operation performance of the internal combustion engine at the time of starting the internal combustion engine, and the like;
A second correction amount calculating means for calculating an increase correction amount of the fuel injection amount based on the secondary air flow rate when supplying the secondary air;
Third correction amount calculating means for calculating a correction amount of the fuel injection amount based on a variation factor of the air-fuel ratio in order to maintain the purification performance of the exhaust purification device;
When the secondary air is supplied, the larger one of the increase correction amounts by the first and second correction amount calculation means is selected, and the selected increase correction amount and the correction amount by the third correction amount calculation means are selected. Fuel amount correction means for correcting the fuel injection amount for each time by adding
A fuel injection amount control apparatus for an internal combustion engine, comprising: Applied to an internal combustion engine configured to supply secondary air upstream of an exhaust purification device provided in an exhaust passage of the internal combustion engine using secondary air supply means,
First correction amount calculating means for calculating an increase correction amount of the fuel injection amount so as to ensure the operation performance of the internal combustion engine at the time of starting the internal combustion engine, and the like;
A second correction amount calculating means for calculating an increase correction amount of the fuel injection amount based on the secondary air flow rate when supplying the secondary air;
Third correction amount calculating means for calculating a correction amount of the fuel injection amount based on a variation factor of the air-fuel ratio in order to maintain the purification performance of the exhaust purification device;
At the time of secondary air supply, either the added value of each correction amount by the first or third correction amount calculation means or the correction amount by the third correction amount calculation means, and the increase by the second correction amount calculation means Fuel amount correction means for correcting the fuel injection amount in each case using the larger one of the correction amounts;
A fuel injection amount control apparatus for an internal combustion engine, comprising:

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