JP2009030615A - Method of controlling learning of air-fuel ratio of dual-injection internal combustion engine on vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling the learning of air-fuel ratio capable of quickly and accurately performing the control of learning of air-fuel ratio for each of both injectors in a dual-injection internal combustion engine on a vehicle. <P>SOLUTION: In the vehicle driven by the dual-injection internal combustion engine 100 having an injector 111 for cylinder injection and an injector 112 for intake passage injection, when the control of learning of air-fuel ratio for learning the learned value of air-fuel ratio of the internal combustion engine is performed, the internal combustion engine is steadily operated, and the control of learning of air-fuel ratio is performed by jetting fuel from only one of the injector for cylinder injection and the injector for intake passage injection. After the learning control is completed, the control of learning of air-fuel ratio is performed by jetting fuel from only the other of these injectors. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air-fuel ratio learning control method for a dual injection internal combustion engine in a hybrid vehicle. More specifically, the present invention relates to an in-cylinder injector that injects fuel into a cylinder and an intake passage or an intake port. The present invention relates to an air-fuel ratio learning control method for a dual-injection internal combustion engine that includes a dual-injection internal-combustion engine that includes an injector for injecting intake passage and that is driven by auxiliary power.

  In general, a hybrid vehicle driven by an internal combustion engine and auxiliary power such as an electric motor is known.

  In addition, an in-cylinder injector for injecting fuel into the cylinder and an intake-path injector for injecting fuel into the intake passage or the intake port are provided according to the operating state of the engine. By switching and using these injectors, for example, stratified combustion in the low-load operation region and homogeneous combustion in the high-load operation region are realized, or fuel is injected at a predetermined share rate according to the operation state, 2. Description of the Related Art A so-called dual injection internal combustion engine that improves fuel consumption characteristics and output characteristics is known.

  Furthermore, in an internal combustion engine, in order to optimize various performances such as output characteristics, exhaust characteristics, and drivability in response to various operating conditions, the air-fuel ratio of the air-fuel mixture supplied to the engine is a target that matches the operating conditions. Feedback correction control is performed to the air-fuel ratio. In order to improve the accuracy of the feedback correction control, air-fuel ratio learning control for learning the air-fuel ratio learning value is executed, and this air-fuel ratio learning value is reflected in the feedback correction control.

By the way, when such air-fuel ratio feedback correction control and air-fuel ratio learning control are performed by an internal combustion engine mounted on a hybrid vehicle, some of the hybrid vehicles have their internal combustion engines stopped depending on their running conditions. In this case, the air-fuel ratio learning control is not executed. As a result, the air-fuel ratio learning control may not be completed early, and more accurate air-fuel ratio feedback correction control may not be performed. Therefore, in Patent Document 1, in order to deal with such a problem, a learning region for learning the air-fuel ratio learning value is divided into a plurality of regions according to the operating state, and at least one learning region is the center in the learning region. A technique has been proposed in which the required output distribution to the internal combustion engine and auxiliary power is determined so as to learn the air-fuel ratio learning value in the vicinity, and the air-fuel ratio learning control is completed early by forcibly performing feedback operation. .
JP 2000-291471 A

  However, the technique described in Patent Document 1 relates to an internal combustion engine having only one injector, and is directed to an in-cylinder injector that injects fuel into a cylinder and an intake passage or an intake port. The present invention is not related to a dual injection type internal combustion engine having an intake passage injection injector for injecting fuel. Even if the air-fuel ratio learning control is completed for only one injector at an early stage, the air-fuel ratio learning control for each of the injectors is not completed. Since it is difficult to grasp whether or not a change in the fuel ratio has occurred, the dual injection internal combustion engine is required to perform the air-fuel ratio learning control for each of both injectors early and accurately.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an air-fuel ratio learning control method capable of quickly and accurately performing air-fuel ratio learning control for each of both injectors in a dual injection internal combustion engine in a hybrid vehicle. .

  An air-fuel ratio learning control method for a dual injection type internal combustion engine in a hybrid vehicle according to an embodiment of the present invention that achieves the above object is a dual injection type internal combustion engine including an in-cylinder injector and an intake manifold injector and an auxiliary device. In the hybrid vehicle driven by power, when the air-fuel ratio learning control for learning the air-fuel ratio learning value of the internal combustion engine is executed, the internal combustion engine is operated steadily, and the in-cylinder injector and the intake passage injection injector The fuel is injected only from either one of them, the air-fuel ratio learning control is executed, and after the learning control is completed, the fuel is injected only from one of the in-cylinder injector and the intake manifold injector. The air-fuel ratio learning control is executed.

  Here, after the air-fuel ratio learning control of both the in-cylinder injector and the intake passage injector is completed, dual injection from both the in-cylinder injector and the intake passage injector is permitted. May be.

  According to the air-fuel ratio learning control method for a dual injection internal combustion engine in a hybrid vehicle according to an aspect of the present invention, when the air-fuel ratio learning control for learning the air-fuel ratio learning value of the internal combustion engine is executed, the internal combustion engine is stationary. The air-fuel ratio learning control is executed by injecting fuel only from one of the in-cylinder injector and the intake manifold injector. Then, after the learning control is completed, the fuel is injected only from the other one of the in-cylinder injector and the intake manifold injector, and the air-fuel ratio learning control is executed. Therefore, since the air-fuel ratio learning control is executed in the steady operation state of the internal combustion engine, the air-fuel ratio learning control can be performed accurately and promptly without fluctuation in the fuel injection amount. In addition, since air-fuel ratio learning control is executed for each one of the in-cylinder injector and the intake manifold injector, the air-fuel ratio learning control for each of both injectors can be performed early and accurately. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  First, a schematic configuration of a hybrid vehicle to which the present invention is applied will be described with reference to FIG.

  The hybrid vehicle shown in FIG. 1 has an engine 100 that is an internal combustion engine and a motor 2 that is auxiliary power as drive sources. The hybrid vehicle also has a generator 3 that receives the output of the engine 100 to generate power. The engine 100, the motor 2, and the generator 3 are connected to each other via the power split mechanism 4. The power split mechanism 4 is configured by, for example, a planetary gear mechanism, and has a role of distributing the output of the engine 100 to the generator 3 and the drive wheels 7 and a role of transmitting the output from the motor 2 to the drive wheels 7. The power split mechanism 4 also has a role as a transmission for driving force transmitted to the drive wheels 7 via the differential gear 5 and the drive shaft 6.

  The motor 2 is an AC synchronous motor, for example, and is driven by AC power. The inverter 9 converts the electric power stored in the battery 8 from direct current to alternating current and supplies it to the motor 2, and converts the electric power generated by the generator 3 from alternating current to direct current to store it in the battery 8. Is. The generator 3 has basically the same configuration as the motor 2 described above, and has a function as an AC synchronous motor. The motor 2 is mainly for outputting a driving force, whereas the generator 3 is mainly for receiving the output of the engine 100 to generate electric power.

  The motor 2 mainly generates a driving force, but can also generate electric power (regenerative power generation) using the rotation of the driving wheels 7. At this time, since the regenerative brake is applied to the drive wheel 7, the hybrid vehicle can be braked by using this together with the foot brake and the engine brake. On the contrary, the generator 3 generates electric power mainly by receiving the output of the engine 100, but can also function as a motor by receiving electric power from the battery 8 via the inverter 9.

  Here, an engine 100 as a dual injection internal combustion engine to which the present invention is applied will be described with reference to FIG. The engine 100 includes a plurality of cylinders, and each cylinder is connected to a common surge tank 103 via a corresponding intake branch pipe 102. The surge tank 103 is connected to an air cleaner 105 via an intake duct 104. An air flow meter 118 and a throttle valve 107 driven by a step motor 106 are disposed in the intake duct 104. The throttle valve 107 is controlled so as to open and close the intake duct 104 almost in synchronization with the depression of the accelerator pedal 110. On the other hand, each cylinder is connected to a common exhaust manifold 108, and this exhaust manifold 108 is connected to a three-way catalytic converter 109. Reference numeral 119 denotes a spark plug disposed at the top of the combustion chamber.

  For each cylinder, an in-cylinder injector 111 for injecting fuel into the cylinder and an intake passage injector 112 for injecting fuel into the intake port or intake passage are provided. It has been. These injectors 111 and 112 are controlled based on output signals of an engine electronic control unit (hereinafter referred to as engine ECU) 20 described later. Each in-cylinder injector 111 is connected to a common fuel distribution pipe (not shown), and this fuel distribution pipe is connected to a fuel distribution pipe via a check valve that can flow toward the fuel distribution pipe. Connected to the fuel pump.

  On the other hand, each intake passage injector 112 is also connected to a common fuel distribution pipe (not shown), and the fuel distribution pipe and the high pressure fuel pump are connected to an electric motor driven low pressure fuel pump via a common fuel pressure regulator. It is connected. Furthermore, the low pressure fuel pump is connected to the fuel tank via a fuel filter. The fuel pressure regulator is configured to return a part of the fuel discharged from the low pressure fuel pump to the fuel tank when the fuel pressure of the fuel discharged from the low pressure fuel pump becomes higher than a predetermined set fuel pressure. Therefore, the fuel pressure supplied to the intake manifold injector 112 and the fuel pressure supplied to the high-pressure fuel pump are prevented from becoming higher than the set fuel pressure.

  In the hybrid vehicle having the above-described configuration, for example, at the time of starting or a light load, only the motor 2 is driven by the electric power from the battery 8 using the characteristics of the motor 2 that can generate high torque in a low rotation state. The hybrid vehicle is driven by the driving force of the motor 2. When a certain speed is obtained and the load becomes high, the engine 100 is driven, and the driving force of the engine 100 and the driving force of the motor 2 driven by the electric power generated by the generator 3 by the output of the engine 100 are driven. And the hybrid vehicle is driven. Furthermore, when further output is required, such as during full-open acceleration, the motor 2 is driven by both the electric power from the generator 3 and the electric power from the battery 8, and the driving force of the engine 100 is also increased. And the driving force of the motor 2 drive the hybrid vehicle. Further, at the time of deceleration or braking, regenerative power generation is performed by the motor 2 using the rotational force of the drive wheels 7 to regeneratively brake the hybrid vehicle. Further, when the charge amount of the battery 8 is reduced, the engine 100 is driven even when the load is light, the generator 3 generates power using the output of the engine 100, and the battery is connected via the inverter 9. 8 can be used for charging.

  Here, several electronic control units (ECUs) that control the hybrid vehicle as described above will be described again with reference to FIG. The drive by the engine 100 and the electrical drive by the motor 2 (and the generator 3), which are characteristic as a hybrid vehicle, are comprehensively controlled by the main ECU 10. In a normal operating state, the main ECU 10 determines the output distribution to the engine 100 and the motor 2 so that the energy efficiency is optimal, and controls the engine 100, the motor 2 and the generator 3 based on this required output distribution. Therefore, each control command is output to the engine ECU 20 and the motor ECU 30.

  The engine ECU 20 and the motor ECU 30 also transmit information on the engine 100, the motor 2, and the generator 3 to the main ECU 10. A battery ECU 40 that controls the battery 8 and a brake ECU 50 that controls the brake are also connected to the main ECU 10. The battery ECU 40 monitors the state of charge of the battery 8 and outputs a charge request command to the main ECU 10 when the amount of charge is insufficient. The main ECU 10 that has received the charge request performs control to generate power by the generator 3 in order to charge the battery 8. The brake ECU 50 controls the hybrid vehicle, and controls the regenerative braking by the motor 2 together with the main ECU 10.

  These ECUs consist of digital computers, and are equipped with ROM (Read Only Memory), RAM (Random Access Memory), CPU (Microprocessor), input port and output port, etc. which are connected to each other via a bidirectional bus. ing. Various sensors described below are connected to the engine ECU 20. That is, a throttle opening sensor 113 that generates an output voltage proportional to the opening of the throttle valve 106, a surge tank 103, and an intake pressure sensor 114 that generates an output voltage proportional to the intake pressure. A water temperature sensor 115 that generates an output voltage proportional to the cooling water temperature, an air-fuel ratio sensor 116 that is attached to the exhaust manifold 108 upstream of the catalyst 109, and an accelerator pedal 110, and an accelerator that generates an output voltage proportional to the amount of depression. An opening sensor 117 and an air flow meter 118 that generates an output voltage proportional to the intake air amount are connected to an input port of the engine ECU 20 via an AD converter (not shown). In addition, a rotational speed sensor 120 that generates an output pulse representing the engine rotational speed is connected to the input port.

The air-fuel ratio sensor 116 of the present embodiment is an O ₂ sensor and has a characteristic that its output changes according to the oxygen concentration in the exhaust gas, and combustion is performed in the engine 100 from the output of the air-fuel ratio sensor 116. Whether the air-fuel ratio of the air-fuel mixture is rich or lean with respect to the stoichiometric air-fuel ratio can be detected on-off. Note that, as the air-fuel ratio sensor 116, a full-range air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned in the engine 100 may be used. The fuel injection amount set in the ROM of the engine ECU 20 corresponding to the engine operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 117, the air flow meter 118, and the engine speed sensor 120 described above. A value of (fuel injection time), a share ratio, a correction value based on the engine coolant temperature, and the like are mapped and stored in advance.

  In the hybrid vehicle having the above-described configuration, the engine 100 and the motor 2 are used in combination as the drive source. Therefore, when a certain driving force is required as the vehicle, the distribution of the output of the engine 100 and the output of the motor 2 is distributed. By changing, the output of the engine 100 and the motor 2 can be changed without changing the total output required by the vehicle. That is, when a certain driving force is required as a vehicle, if the output of the motor 2 is increased, the output of the engine 100 can be suppressed correspondingly, and conversely, if the output of the motor 2 is suppressed, the output of the engine 100 is increased accordingly. Can be increased. The air-fuel ratio learning control method of the present embodiment uses such characteristics for air-fuel ratio learning control.

  Here, an embodiment of the air-fuel ratio learning control method for learning the air-fuel ratio learning value of the engine 100 having the above-described configuration will be described with reference to the flowchart of FIG. This control is performed, for example, immediately after the engine 100 is started at a predetermined time during traveling after the hybrid vehicle is started by the driving force of the motor 2.

  First, when control is started, it is determined in step S301 whether or not the engine 100 is capable of steady operation. The determination as to whether or not steady operation is possible can be made, for example, based on whether or not the amount of charge stored in the battery 8 is sufficient based on information from the battery ECU 40 and traveling by the motor 2 is possible. It should be noted that when the load required for engine 100 exceeds a predetermined value or when the cooling water temperature of engine 100 is equal to or lower than a predetermined value, it is determined that steady operation is impossible, based on signals from accelerator opening sensor 117 and water temperature sensor 115. It is preferable to do this. This is because in such a case, stable operation of the engine 100 is not guaranteed. Thus, when it is determined that the steady operation is impossible, this control routine is once terminated.

  On the other hand, if it is determined in step S301 that the steady operation is possible, the process proceeds to step S302, and the engine 100 is set to the steady operation state. This steady operation state means that, for example, the opening of the throttle valve 107 of the engine 100 is controlled to be constant based on the output signal from the throttle opening sensor 113 and the fuel injection amount is controlled to be constant, so that the load factor and rotation It means a state where the number does not fluctuate, in other words, a state where there is no transient operation. Note that a plurality of steady operation states may be set with different operation regions. This is because the accuracy of the air-fuel ratio learning control is improved for each region.

  By the way, in the engine 100 according to the present embodiment, for example, the ratio of injection by the in-cylinder injector 111 and the intake manifold injector 112 is determined in accordance with the operation region or condition as shown in FIG. ing. In FIG. 4, “direct injection 100%” means a region (X = 100) in which injection is performed only from the in-cylinder injector 111, and “direct injection 0 to 20%” It means that the injection from the internal injection injector 111 is in the range of 0 to 20% (X = 0 to 20). For example, in the region of “direct injection 40%”, the injection from the in-cylinder injector 111 is 40%, the injection from the intake passage injector 112 is 60%, and the sharing ratio of both is 40:60. .

  Returning to the flowchart of FIG. 3, in step S <b> 303 after the engine 100 is set in the steady operation state in step S <b> 302, the entire fuel injection amount controlled to be constant is injected only from the in-cylinder injector 111. The operation at “direct injection 100%” is executed. In step S304, air-fuel ratio learning control including injector characteristic learning and air flow meter characteristics for the in-cylinder injector 111, which will be described later, is executed. Further, the process proceeds to step S305 to determine whether or not the air-fuel ratio learning control is completed. If not, the process returns to step S304 and the air-fuel ratio learning control is continued. A method for determining whether or not the air-fuel ratio learning control has been completed will be described in detail later.

  Therefore, when the air-fuel ratio learning control for the in-cylinder injector 111 is completed, the process proceeds to step S306, where the entire fuel injection amount controlled to be constant is injected only from the intake manifold injector 112. The operation at “direct injection 0%”, that is, “port injection 100%” is executed. In step S307, air-fuel ratio learning control including injector characteristic learning for the intake manifold injector 112 is executed. Further, the process proceeds to step S308 to determine whether or not the air-fuel ratio learning control is completed. If not, the process returns to step S307 and the air-fuel ratio learning control is continued. When there is a further output request from the hybrid vehicle during the air-fuel ratio learning control in the steady operation state of the engine 100 described above, the main ECU 10 increases the output distribution from the motor 2 while the output from the engine 100 remains constant. As described above, each control command can be output to the engine ECU 20 and the motor ECU 30 as described above.

  Here, an air-fuel ratio feedback and air-fuel ratio learning control routine which is a precondition for determining whether or not the air-fuel ratio learning control including the injector characteristic learning for the in-cylinder injector 111 or the intake manifold injector 112 is completed. This will be described with reference to the flowchart of FIG. The control routine of FIG. 5 is executed every predetermined time (or every predetermined rotation). First, in step S501, it is determined whether or not a predetermined air-fuel ratio feedback control region. Specifically, for example, it is at the time of homogeneous stoichiometric combustion and is not in a fully open region. If it is not in the air-fuel ratio feedback control region, this routine is terminated (at this time, the air-fuel ratio feedback correction coefficient γ is held at the previous value), and the process proceeds to step S502 and subsequent steps only when it is established.

  Here, the air-fuel ratio feedback correction coefficient γ is for detecting the air-fuel ratio from the oxygen concentration in the exhaust gas by the air-fuel ratio sensor 116 and performing feedback correction so that this air-fuel ratio becomes the target air-fuel ratio. For example, when the air-fuel ratio is set to the stoichiometric air-fuel ratio, the fuel injection amount is gradually increased with respect to the air-fuel ratio feedback correction coefficient γ while the air-fuel ratio detected by the air-fuel ratio sensor 116 is richer than the stoichiometric air-fuel ratio. When the air-fuel ratio detected by the air-fuel ratio sensor 116 is changed from rich to lean, a value for increasing the fuel injection amount is given skippingly in consideration of the improvement in response.

  Conversely, while the air-fuel ratio detected by the air-fuel ratio sensor 116 is leaner than the stoichiometric air-fuel ratio, a value that gradually increases the fuel injection amount is given to the air-fuel ratio feedback correction coefficient γ. When the air-fuel ratio detected by (1) changes from lean to rich, a value for reducing the fuel injection amount is given in a skipping manner in consideration of improvement in response. In this way, the air-fuel ratio feedback correction coefficient γ is generated in order to always maintain the air-fuel ratio at the stoichiometric air-fuel ratio.

  Therefore, in step S502, it is determined whether the air-fuel ratio is rich or lean based on the output of the air-fuel ratio sensor 116. If the air-fuel ratio is rich, the process proceeds to step S503, and the air-fuel ratio feedback correction coefficient γ is decreased by a predetermined integral I with respect to the previous value. Conversely, if the air-fuel ratio is lean, the process proceeds to step S504. The feedback correction coefficient γ is increased by a predetermined integral I with respect to the previous value. At the time of rich / lean reversal, the air-fuel ratio feedback correction coefficient γ is increased or decreased by a predetermined proportional amount P (>> I) with respect to the previous value, but the illustration is omitted for the sake of simplicity.

  Next, in step S505, an average value γave of the air-fuel ratio feedback correction coefficient γ is calculated. Specifically, for example, from the latest stored value γ1 of the air-fuel ratio feedback correction coefficient at the time of inversion of rich → lean and the latest stored value γ2 of the air-fuel ratio feedback correction coefficient at the time of inversion of lean → rich, an average value is obtained. γave = (γ1 + γ2) / 2 is calculated. In the next step S506, a deviation Δγ = γave −1 from the reference value “1” of the average γave of the air-fuel ratio feedback correction coefficient is calculated.

  In step S507, a predetermined ratio G of the deviation Δγ (G is a learning gain, 0 <G <1) is added to the current air-fuel ratio learned value Lγ, as shown in the following equation, and a new air-fuel ratio learned value is obtained. Lγ is calculated.

Lγ = Lγ + Δγ × G
In step S508, the learning count counter is incremented by 1, and the learning count value “n” is calculated. In step S509, it is determined whether the learning number count value “n” is equal to or greater than a predetermined number (for example, 30 times). When the learning number count value “n” exceeds the predetermined number, that is, “Yes”, the process proceeds to step S510, and the air-fuel ratio learning value is updated. Specifically, the air-fuel ratio learning value “Lγ” calculated in step S507 described above is used as the air-fuel ratio learning reflecting value reflecting the learning result. In step S511, the air-fuel ratio learning completion flag F is set to on (= 1). On the other hand, when the predetermined number of times is not exceeded, that is, when “No”, the learning accuracy is not sufficient and the process proceeds to step S512, and the update of the air-fuel ratio learning value is prohibited. In step S513, the air-fuel ratio learning completion flag F is set to off (= 0).

  Therefore, in step S305 or step S308 of the flowchart of FIG. 3 described above, the determination as to whether the air-fuel ratio learning control including the injector characteristic learning for the in-cylinder injector 111 or the intake manifold injector 112 has been completed is as follows: This can be done depending on whether the air-fuel ratio learning completion flag F is on or off.

  After the air-fuel ratio learning control is completed for both the in-cylinder injector 111 and the intake manifold injector 112, the process proceeds to step S309 in the flowchart of FIG. 3 to turn on the normal injection ratio permission flag. The routine is terminated as follows. After the injection dividing permission flag is turned on, fuel can be injected from both the in-cylinder injector 111 and the intake passage injector 112 at a predetermined share rate according to the operating conditions and the like. .

  As described above, in the present embodiment, since the air-fuel ratio learning control is executed in a steady operation state in which the fuel injection amount of the engine 100 does not vary, the air-fuel ratio learning control can be performed accurately and promptly. In addition, since air-fuel ratio learning control is executed for each one of the in-cylinder injector and the intake manifold injector, the air-fuel ratio learning control for each of the two injectors must be performed early and accurately. Can do.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

1 is a block diagram showing a schematic configuration of a hybrid vehicle to which the present invention is applied. It is a cross-sectional schematic diagram which shows schematic structure of the dual injection type internal combustion engine to which this invention is applied. It is a flowchart which shows an example of the control routine in embodiment of this invention. It is a graph which shows an example of the fuel injection share of the dual injection type internal combustion engine to which this invention is applied. It is a flowchart which shows an example of the air fuel ratio learning control routine in embodiment of this invention.

Explanation of symbols

10 Main ECU
20 Engine ECU
100 engine (dual injection internal combustion engine)
111 In-cylinder injector 112 Intake passage injector 116 Air-fuel ratio sensor

Claims (2)

In a vehicle driven by a dual injection type internal combustion engine including an in-cylinder injector and an intake manifold injector,
When the air-fuel ratio learning control for learning the air-fuel ratio learning value of the internal combustion engine is executed, the internal combustion engine is steadily operated, and fuel is supplied from only one of the in-cylinder injector and the intake manifold injector. Injecting and executing air-fuel ratio learning control;
A dual-injection internal combustion engine for a vehicle, comprising: a step of performing air-fuel ratio learning control by injecting fuel only from one of the in-cylinder injector and the intake manifold injector after the learning control is completed Engine air-fuel ratio learning control method.   A step of permitting dual injection from both the in-cylinder injector and the intake passage injector after the air-fuel ratio learning control of both the in-cylinder injector and the intake passage injector is completed. An air-fuel ratio learning control method for a dual injection internal combustion engine in a vehicle according to claim 1, comprising:

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