JP4749281B2 - Electronic control device and engine control method - Google Patents

Description

The present invention relates to an electronic control unit and an engine control method for controlling an intake air amount so that an engine speed during idling matches a target speed.

  In general, during engine idling, intake air amount increase / decrease correction control is performed to stabilize the engine speed. As a device for this purpose, a bypass passage that bypasses the throttle valve and connects the upstream side and the downstream side of the intake passage is conventionally provided, and an idle speed control valve (ISCV) is provided in the bypass passage. (For example, refer to Patent Document 1).

  Then, during idling when the throttle valve is fully closed, feedback control of the ISCV opening is performed in order to obtain a predetermined idling engine speed according to the engine coolant temperature and load conditions such as an air conditioner. Through such feedback control of the ISCV opening, the air flow rate in the bypass passage is optimized, and the idle rotation speed is controlled to be the target rotation speed according to the cooling water temperature and load conditions.

Further, during non-idle operation other than during idle operation, the opening of the ISCV is maintained so as to be the feedback correction amount obtained during feedback control.
This will be described with reference to FIG. For example, when the engine speed decreases from the target speed as shown in FIG. 1A by the operation of the clutch, the electronic control unit (ECU) causes the engine speed to approach the target speed. A feedback correction amount is obtained from the deviation between the rotation speed and the target rotation speed, and the opening of the ISCV is adjusted based on the feedback correction amount.
Next, when the engine operating state shifts from the idle operation state to the non-idle operation state, the feedback correction amount calculated by the electronic control unit (ECU) is maintained even during non-idle operation, and this feedback correction amount is supported. The opening degree of the ISCV is maintained so as to be the opening degree (see FIG. 1B).

  In Patent Document 2, in order to stabilize the control at the time of sudden deceleration from the high speed range and to set the target idling speed low, when sudden deceleration is detected, feedback control with poor followability is stopped, The technique which performs feedforward control according to the time-auxiliary air control valve opening characteristic by the defined reference | standard model is disclosed.

JP-A-7-332137 Japanese Patent No. 2775514

However, since the opening of the ISCV is maintained at the opening just before the idle speed control is terminated, the engine speed is high when the vehicle is decelerating, that is, when the depression of the accelerator pedal is released and the idle control is started. It is maintained in a state and causes noise and fuel consumption deterioration. In particular, noise becomes more noticeable when the drive system is set to neutral during deceleration travel. Patent Document 2 also does not disclose a technique for solving such a problem.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an electronic control device and an engine control method that can keep the engine speed low when decelerating with a drive system neutral. .

In order to achieve such an object, an electronic control device of the present invention is an electronic control device for controlling an engine provided in a vehicle so that the engine speed matches a target speed when in an idling state. The feedback correction amount calculating means for calculating the feedback correction amount in the rotational speed feedback control performed at the time, and the feedback correction amount calculating means when the rotational speed feedback control is interrupted because it is not in the idle operation state. A holding unit that holds the feedback correction amount as a holding correction amount, and a feedback that controls the engine speed based on the holding correction amount held in the holding unit when the idling operation state is resumed and the rotation speed feedback control is resumed. Control means, and the holding means is the feed Correction amount smaller than the holding correction amount held when the rotation speed feedback control is interrupted when the increase amount per predetermined time of the feedback correction amount calculated by the torque correction amount calculating means is larger than the predetermined value Is stored, and when it is determined that the traveling state of the vehicle is a stable traveling state in which engine stall does not occur, the stored correction amount is substituted into the holding correction amount .

In the electronic control apparatus, the correction amount smaller than the holding correction amount is a correction amount that makes the feedback correction amount a value that decreases the engine speed or a value that decreases the intake air amount .

In the electronic control unit, the holding unit is a stable unit that does not cause the engine stall when at least one of the engine speed, the vehicle speed, the throttle opening degree, and the intake pipe pressure becomes a predetermined value or more. It is determined that the vehicle is in a running state.

In the electronic control device, the feedback correction amount calculating means may calculate an increase amount of the feedback correction amount per predetermined time by using the feedback correction amount and the smoothed value of the feedback correction amount or the previous value of the feedback correction amount. And a difference from the current value .

The engine control method of the present invention is an engine control method that is provided in a vehicle and controls the engine. The engine speed control is performed so that the engine speed matches the target speed when in an idling state. The feedback correction amount calculated in the step of calculating the feedback correction amount and the feedback correction amount calculated in the step of calculating the feedback correction amount when the rotational speed feedback control is interrupted due to not being in the idling state. Holding in the holding means, and controlling the engine speed based on the holding correction amount held in the holding means when the engine is in the idle operation state and the rotational speed feedback control is resumed. , The step of holding in the holding means is the feedback correction When the increase amount per predetermined time of the feedback correction amount issued in the step of calculating the value becomes larger than a predetermined value, the correction amount smaller than the retained correction amount stored when the rotation speed feedback control is interrupted is stored. In addition, when it is determined that the traveling state of the vehicle is a stable traveling state in which engine stall does not occur, the stored correction amount is substituted into the holding correction amount .

  According to the present invention, the engine speed can be kept low when decelerating with the drive system set to neutral.

  The best embodiment of the present invention will be described with reference to the accompanying drawings.

First, the configuration of the present embodiment will be described with reference to FIG.
An intake passage 11 and an exhaust passage 12 communicate with the engine 10. The intake passage 11 includes an air cleaner 14, a surge tank 20, an intake branch pipe 13, and the like, and a throttle valve 17 that controls conduction of the intake passage 11 is disposed therein.

  The throttle valve 17 is a valve that operates in conjunction with an accelerator pedal (not shown), and in the vicinity thereof, an idle switch 18 that is turned on when the throttle valve 17 is fully closed, and a throttle opening that detects the opening of the throttle valve 17. A degree sensor 19 is provided.

  The intake passage 11 is provided with a bypass passage 15 that bypasses the throttle valve 17. The bypass passage 15 incorporates an idle speed control valve (hereinafter referred to as ISCV) 16 for controlling the conduction state. The ISCV 16 is a valve that can realize an arbitrary opening degree by being duty-controlled, and is driven by an ECU (electronic control unit) 30.

  An intake pressure sensor 21 that detects intake pressure is disposed in the surge tank 20, and an injector 22 that injects fuel to the engine 10 is disposed in the intake branch pipe 13. Both the intake pressure sensor 21 and the injector 22 are connected to the ECU 30. That is, the ECU 30 controls the ISC opening and also has a function of controlling the amount of fuel injected from the injector 22, so that an appropriate air amount is obtained for the intake air amount obtained from the engine speed and the intake pressure. Using the amount that can realize the fuel ratio as the basic injection amount, the fuel injection amount subjected to various corrections is obtained by calculation, and the injector 22 is driven.

Next, the configuration of the ECU 30 will be described with reference to the block diagram of FIG. The ECU 30 includes a CPU 32, a ROM 33 that stores predetermined control programs and maps, a RAM 34 that temporarily stores calculation results of the CPU 32, a backup RAM 35 that stores data stored in the RAM 34, and the like. The ECU 30 is configured as a logical operation circuit in which these units, the input interface circuit 31, and the output interface circuit 36 are connected by a bus. Further, in the CPU 32, the first buffer circuit 41 to be described later, a second buffer circuit 42 is provided, CPU 3 2 stores control information of the engine 10 to these buffer circuits.

  The input interface circuit 31 includes an intake pressure sensor 21, a water temperature sensor 24 that detects the temperature of the cooling water of the engine 10, an engine speed sensor 33 that detects the engine speed, and a change in the crank angle of the engine 10 at a predetermined rate. Are connected to a crank angle sensor 31, a throttle opening sensor 19, a vehicle speed sensor 32 for detecting the vehicle speed, an idle switch 18, and the like. Then, the CPU 32 reads output signals from the sensors and the idle switch 18 through the input interface circuit 31 as input values. Then, the CPU 32 suitably controls the throttle motor 37, the injector 22, the spark plug 23, the ISCV motor 38, and the like connected to the output interface circuit 36 based on these input values. The throttle motor 37 is a motor that drives the throttle valve 17 according to the control of the ECU 30, and the ISCV motor 38 is a motor that drives the ISCV according to the control of the ECU 30.

In the idling state, ECU 30 determines the operating state of the engine based on the detection signal from each sensor, and appropriately updates the learning value during idle (hereinafter also referred to as DLRN) based on the determination result. The learning value is set as the target opening, and the opening of the ISCV 16 is feedback-controlled so that the actual engine speed becomes the speed corresponding to the target opening.

  When the clutch position is changed from the clutch disengaged state to the half-clutch state by the operation of the clutch mechanism, the engine speed decreases from the target speed as shown in FIG. When the engine speed decreases, the ECU 30 determines a feedback correction amount (unit%) (hereinafter also referred to as DFB) from the deviation between the engine speed and the target speed in order to bring the engine speed closer to the target speed. And the opening of the ISCV 16 is adjusted by this feedback correction amount. By controlling the idling speed, the intake air amount of the engine is increased and the engine operation is stabilized.

In this embodiment, the ECU 30 obtains a smoothing value (unit%) (hereinafter also referred to as “DFBN _n” ) of the feedback correction amount for idling rotational speed control, and the feedback correction amount (DFB) Compare. difference between the feedback correction amount (DFB _n) and smoothed value (DFBN _n) becomes larger than a predetermined threshold value (S), smoothed value when compared to the immediately preceding (DFBN _{n −1} ) is stored in the buffer circuit as a feedback correction amount (DFB _n ) When the accelerator pedal is depressed and the throttle opening is greatly opened, the vehicle speed increases and the vehicle speed (2 k m / h) immediately, and when this control is completed, the idle opening just before the end of the control is maintained for use in the idle speed control later. The idle opening degree becomes a state so that wide open one when the vehicle speed reaches the rapidly 2 k m / h. Then, during deceleration words, depression of the accelerator pedal is released, the idle switch is turned ON When the idling speed control is started based on the throttle opening that is held, the engine speed becomes high, the noise increases, and the fuel consumption also deteriorates. for threshold (S) is to prevent such problems, a idle speed control ending condition speed (2 k m / h) as would quickly reach a throttle opening, that is, rapid throttle opening This is a value for determining that the opening is wide.
The annealing value (DFBN _n ) is a moving average value of the feedback correction amount obtained a predetermined number of times, and can be obtained by the following equation.
Annealing value (DFBN _n ) = DFBN _n−1 + (DFB−DFBN _n−1 ) / K
The coefficient n is the current value, and n-1 represents the previous value. K represents an annealing coefficient.

Further, ECU 30 is useful when the vehicle speed exceeds a predetermined speed (2 k m / h in this embodiment), the accelerator is depressed, the idle switch 18 is turned off to terminate the idle speed feedback control. Thereafter, the accelerator is depressed, and the engine speed exceeds the target speed. At this time, the opening of the ISCV is held at the opening just before the idle speed control is ended (see FIG. 4B).

When the ECU 30 determines that the vehicle speed, the engine speed, and the throttle opening are equal to or greater than the predetermined values and the engine 10 is not likely to stall, the ECU 30 stores the opening of the ISCV as a previous feedback correction amount (DFB _n ). The opening is lowered to the annealing value (DFBNn-1) (see FIG. 4C). By performing such control, when the clutch device is disengaged during deceleration and the engine 10 is in the neutral state, the engine 10 can be kept at a low speed, so that noise can be suppressed and fuel consumption can be improved.

In the above description, the case where the engine speed has decreased in the half-clutch state has been described as an example. However, during ISCV feedback control, the engine speed has decreased and the opening of the ISCV has greatly opened. A similar problem occurs when the vehicle is driven later.
Even in such a case, the feedback correction amount of the ISCV opening is compared with the annealed value, and the smoothed value when these differences are larger than a predetermined value is stored, and the vehicle When a stable running state is achieved, the opening degree of the ISCV may be lowered to the opening degree of the stored smoothing value.

In the above description, the smoothing value of the feedback correction amount is obtained and compared with the feedback correction amount. However, as shown in FIG. 5, the feedback correction amount (DFB _n ) obtained this time and the previous time By comparing the deviation from the feedback correction amount (DFB _n-1 ) with a threshold value, the change amount of the feedback correction amount can also be obtained.

Further, when the difference between the feedback correction amount (DFB _n ) and the annealing value (DFBN _n ) becomes larger than a predetermined threshold value (S), the annealing value (DFBN _n− when compared immediately before this) is compared. ₁ ) is stored in the buffer circuit as the feedback correction amount (DFB _n ), but the value of the feedback correction amount DFB _n may be stored in the buffer circuit. When the engine is in a non-idle operation and is in a stable state, the opening of the ISCV is lowered to the opening corresponding to the feedback correction amount DFB _n that has been stored.

The control procedure of the ECU 30 will be described with reference to the flowchart shown in FIG.
When this process is started, first, it is determined whether the current vehicle speed is 0 or less than a predetermined speed near 0 and the throttle valve is in a fully closed state or a substantially fully closed state. In this state, it is determined whether or not a feedback control execution condition (F / B condition) is satisfied (step S1).

If it is determined in step S1 that the F / B condition is satisfied, a feedback correction amount (DFB _n ) for controlling the idle rotation speed of the engine 10 to the target rotation speed based on the learning value during idling is calculated. .
The ECU 30 determines the operating state of the engine 10 based on detection signals from the sensors, and obtains a learning value during idling based on the determination result. The ECU 30 determines the feedback correction amount (DFB _n ) using the learned value as a target value for the engine speed so that the actual engine speed approaches the target speed. That is, the deviation between the engine speed and the target speed is obtained and used as the feedback correction amount (DFB _n ).
When the actual engine speed is smaller than the target speed, a correction for adding a feedback correction amount (DFB _n ) is performed. Conversely, when the actual engine speed is larger than the target speed, Correction for subtracting the feedback correction amount (DFB _n ) is performed. If the actual engine speed and the target engine speed match, the feedback correction amount (DFB _n ) used during the previous feedback control is held as it is.

Then, ECU 30 is seeking the calculated feedback correction amount (DFB _n) of a better value (DFBN _n), a deviation between the feedback correction amount (DFB _n) and smoothed value (DFBN _n) (step S2 ). Further, the ECU 30 compares the deviation between the calculated feedback correction amount (DFB _n ) and the tempered value (DFBN _n ) with a threshold value (S) (step S3).
When the deviation between the feedback correction amount (DFB _n ) and the annealing value (DFBN _n ) is smaller than the threshold (step S3 / NO), the ECU 30 waits until the storage timing of the annealing value (DFBN _n ) is reached. (Step S5) When the storage timing is reached (Step S5 / YES), the previous annealing value (DFBN _n-1 ) stored in the first buffer circuit 41 is stored in the second buffer circuit 42, and the first The current annealing value (DFBN _n ) is stored in the buffer circuit 41 (step S7).

As shown in FIG. 4, when the deviation between the feedback correction amount (DFB _n ) and the rectified value (DFBN _n ) becomes larger than the threshold value (step S3 / YES), the ECU 30 causes a large change in the feedback correction amount. An execution flag F indicating that it has become is set to ON (step S4). After that, when it is time to store the annealing value (DFBN _n ), the storage value (DFBN _n ) is tried to be stored, but since the execution flag is set to ON (step S6 / NO), DFBN _n ) is not stored in the first buffer circuit 41. That is, the first buffer circuit 41 holds the smoothed value (DFBN _n-1 ), and the second buffer circuit 42 holds the smoothed value (DFBN _n-2 ) as it is.

  Next, when the current vehicle speed is equal to or higher than a predetermined speed (2 Km / h in the present embodiment) and the throttle valve is in an opened state, the ECU 30 satisfies the feedback control execution condition (F / B condition). It is determined that there is not (step S1 / NO). In this case, it is determined that the engine 10 has shifted from the idle operation state to the non-idle operation, and the control condition has changed from feedback control to a state in which open loop control is performed.

ECU30 determines that the conditions for executing the feedback control is not satisfied (step S1 / NO), in execution flag F is ON, and the feedback correction amount DFB _n calculated in step S2, stored in the first buffer circuit 41 The annealing value DFBN _n−1 is compared. When the feedback correction amount DFB _n is larger than the smoothed value DFBN _n−1 (step S8 / YES), the feedback correction amount (DFB _n ) for determining the opening of the ISCV is stored in the first buffer circuit 41. The annealed value DFBN _n-1 is substituted (step S9). By substituting the smoothing value (DFBN _n-1 ) for the feedback correction amount (DFB _n ) and reducing the intake air amount by lowering the ISCV opening based on this value, the clutch device is disengaged during deceleration and is in the neutral state When this happens, the engine speed can be kept low, so noise can be reduced and fuel consumption can be improved. Note that the control method of decreasing the intake air amount by lowering the ISCV opening when the throttle opening is greatly opened is not limited to this, and is determined in advance when the throttle opening is greatly opened. A control method performed based on the throttle opening may be used. Naturally, the control of the ISCV opening degree does not stall the engine, and suppresses the engine speed to prevent noise.

Next, the control procedure of the ECU 30 will be described in more detail with reference to the flowchart shown in FIG.
When the process is started, the ECU 30 determines whether or not the F / B condition is satisfied (step S11). When it is determined that the F / B condition is satisfied (step S11 / YES), feedback is performed. A correction amount (DFB _n ) and an annealing value (DFBN _n ) are calculated.

Next, the ECU 30 determines that the deviation from the calculated feedback correction amount (DFB _n ) and the simulated value (DFBN _n ) is _{equal to} or greater than a predetermined threshold value (S) , and the feedback correction amount (DFB _n ) is a learned value ( It determines the whether or larger than the value obtained by adding a predetermined value to DLRN) (step S13). The predetermined threshold value (S) is used to determine that the throttle is rapidly opened as in the above-described threshold value. The learning value is a value for correcting aging deterioration and individual differences of the throttle motor and the like. The constant value is a constant and is a value that is designed appropriately by the designer in accordance with the operating conditions and serves as a reference value. The minimum necessary control amount is guaranteed by providing that the feedback correction amount (DFB _n ) is equal to or greater than the sum of the learning value and the constant value . When these conditions are satisfied (step S13 / YES), the execution flag F is turned on, and the learning value (DLRN past value) when the execution flag F is turned on is stored in a buffer circuit (not shown) ( Step S14). If these conditions are not satisfied (step S13 / NO), the execution flag F is not turned on.

Next, the ECU 30 determines that the difference between the feedback correction amount (DFB _n ) and the learned value (DLRN past value) when the execution flag is turned on is smaller than a fixed value, and the feedback correction amount (DFB _n ) is within the update range. It is determined whether the upper limit is not reached (step S15). The difference between the feedback correction amount (DFB _n ) and the learning value (DLRN past value) when the execution flag is turned on is smaller than a certain value, and the feedback correction amount (DFB _n ) is not the upper limit value of the update range. In this case (step S15 / YES), the execution flag is set to OFF (step S16). This defines the update range. The upper limit of the update range is the update limit value, and the lower limit guarantees the minimum required control amount on the condition that it is the sum of the DLRN learned value and the reference value. The constant value is a constant, a value that is designed appropriately by the designer according to the operating conditions, and serves as a reference value for the lower limit of the update range. Similarly, the upper limit value of the update range is a value that can be appropriately changed by the designer according to the operating conditions, and serves as a reference value for the upper limit of the update range.

Next, the ECU 30 waits until the storage timing of the annealing value (DFBN _n ) is reached (step S17). When the storage timing is reached (step S17 / YES), the ECU 30 stores the previous value stored in the first buffer circuit 41. The straight value (DFBN _n-1 ) is stored in the second buffer circuit 42, and the current annealing value (DFBN _n ) is stored in the first buffer circuit 41 (step S19). When the execution flag is set to ON (step S18 / NO), the smoothed value (DFBN _n ) is not stored in the first buffer circuit 41.

  Next, when the current vehicle speed is equal to or higher than a predetermined speed (2 Km / h in the present embodiment) and the throttle valve is in an opened state, the ECU 30 satisfies the feedback control execution condition (F / B condition). It is determined that there is not (step S1 / NO). In this case, it is determined that the engine 10 has shifted from the idle operation state to the non-idle operation, and the control condition has changed from feedback control to a state in which open loop control is performed.

When the ECU 30 determines that the execution condition for the feedback control is not satisfied (step S1 / NO), the ECU 30 determines whether the following determination condition is satisfied.
Execution flag F is set to ON has been that if the vehicle speed is a predetermined value or more is or throttle opening is a predetermined value or more is whether the engine or the rotational speed is a predetermined value or more intake pipe pressure is a predetermined value or more or some feedback correction amount DFB _n There if it meets smoothed value DFBN _n-1 larger or these conditions than is (step S20 / YES), the feedback correction amount (DFB _n), moderation values stored first in buffer circuit 4 1 The value of DFBN _n-1 is substituted (step S21). In addition, the smoothing value and the value of the feedback correction amount DFB _n are substituted into the first buffer circuit 41 (step S22), and the execution flag F is turned off (step S23). The constant value is a value for determining that the vehicle is in a traveling state and that engine stall does not occur.

If the above condition is not satisfied (step S20 / NO), whether the feedback correction amount DFB _n is larger than the learning value (DLRN) or the water temperature measured by the water temperature sensor 24 is equal to or lower than a certain value. Is determined (step S24). If these conditions are satisfied (step S24 / YES), the process is terminated assuming that the engine is not in a stable state. If these conditions are not satisfied, the learning value (DLRN) is substituted for the feedback correction amount DFB _n (step S25), and the feedback correction amount DFB is input to the smoothed value, first buffer circuit 41, and second buffer 42. The value of _n is substituted (step S26).

The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
For example, in the above-described embodiment, the example in which the opening degree of the ISCV is adjusted by driving the stepper motor has been described, but the opening degree of the ISCV may be adjusted by a rotary solenoid.
The present invention can also be implemented when idle rotation control is performed by a system having only an electronic throttle disposed in the intake passage without providing a bypass passage as in the ISCV system described as the embodiment. In this system, an electronic throttle is disposed in an intake passage, an accelerator pedal depression amount is detected by an accelerator sensor, a target throttle opening is set according to an output signal of the accelerator sensor, and a throttle valve opening ( The throttle valve opening is controlled by a motor or the like so that the actual throttle opening) coincides with the target throttle opening. When performing idling speed control, the target throttle speed is set to the target idling speed. The opening is set, and the opening of the throttle valve is controlled by a motor or the like so that the opening of the throttle valve (actual throttle opening) matches the target throttle opening. In the embodiment, the electronic control device is disclosed in which the intake air amount is controlled to set the engine speed to a predetermined speed. However, the present invention is not limited to this, and the engine speed is set to a predetermined speed. It can also be implemented in the case of an electronic control device that controls fuel injection and ignition timing.

It is a figure for demonstrating the conventional control method. It is a figure which shows the structure of an engine and its peripheral device. It is a block diagram which shows the structure of ECU, its input device, and an output device. It is a figure for demonstrating the control method of this invention. It is a figure for demonstrating the other method of calculating | requiring the variation | change_quantity of a feedback correction amount. It is a flowchart which shows the control procedure of ECU. It is a flowchart which shows the other control procedure of ECU.

Explanation of symbols

10 Engine 11 Intake Passage 12 Exhaust Passage 13 Intake Branch Pipe 14 Air Cleaner 15 Bypass Passage 16 ISCV
17 Throttle valve 18 Idle switch 19 Throttle opening sensor 20 Surge tank 21 Intake pressure sensor 22 Injector 23 Spark plug 24 Water temperature sensor 31 Input interface circuit 32 CPU
33 ROM
34 RAM
35 Backup RAM
36 Output interface circuit 37 Motor for throttle 38 Motor for ISCV

Claims (5)

An electronic control device for controlling an engine provided in a vehicle,
Feedback correction amount calculating means for calculating a feedback correction amount in the rotational speed feedback control performed so that the engine rotational speed matches the target rotational speed when in an idle operation state;
Holding means for holding the feedback correction amount calculated by the feedback correction amount calculating means as a holding correction amount when the rotational speed feedback control is interrupted because it is not in the idle operation state;
Feedback control means for controlling the engine speed based on the holding correction amount held in the holding means when the engine is in the idle operation state and restarts the rotation speed feedback control;
The holding unit holds the correction amount to be held when the rotation speed feedback control is interrupted when the increase amount per predetermined time of the feedback correction amount calculated by the feedback correction amount calculating unit is larger than a predetermined value. Storing a smaller correction amount, and substituting the stored correction amount into the holding correction amount when it is determined that the vehicle is in a stable driving state in which engine stall does not occur. An electronic control device.   2. The electronic control unit according to claim 1, wherein the correction amount smaller than the holding correction amount is a correction amount that makes the feedback correction amount a value that decreases the engine speed or a value that decreases the intake air amount. .   The holding means is in a stable running state in which the engine stall does not occur when at least one of the engine speed, the vehicle speed, the throttle opening degree, and the intake pipe pressure becomes a predetermined value or more. The electronic control device according to claim 1, wherein the electronic control device is determined.   The feedback correction amount calculation means calculates an increase amount of the feedback correction amount per predetermined time between the feedback correction amount and the smoothed value of the feedback correction amount, or the previous value and the current value of the feedback correction amount. 3. The electronic control device according to claim 1, wherein the electronic control device is calculated from the deviation. An engine control method for controlling an engine provided in a vehicle,
A step of calculating a feedback correction amount in the rotational speed feedback control performed so that the engine rotational speed matches the target rotational speed when in an idle operation state;
Holding the feedback correction amount calculated in the step of calculating the feedback correction amount in the holding means as a holding correction amount when the rotational speed feedback control is interrupted because it is not in the idle operation state;
Controlling the engine speed based on the holding correction amount held in the holding means when the engine is in the idle operation state and the rotation speed feedback control is resumed.
The step of holding in the holding means is a case where the rotational speed feedback control is interrupted when the amount of increase in the feedback correction amount given by the step of calculating the feedback correction amount per predetermined time is larger than a predetermined value. When a correction amount that is smaller than the holding correction amount held in the vehicle is stored and it is determined that the running state of the vehicle is a stable driving state in which engine stall does not occur, the stored correction amount is used as the holding correction amount. The engine control method is characterized by substituting into.

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