JP2003328833A - Control system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly lead and engine speed to a target speed and precisely maintain the engine speed at the target speed under an idling state after a start. <P>SOLUTION: During an idling state just after an engine start, if an engine speed is lower than a target speed, an intake quantity is gradually increased to bring the engine speed to the target speed, and if the engine speed is higher than the target speed, an intake quantity is gradually reduced. During an idling state just after an engine start, an increase in the engine speed due to overshoot intake air over a reference intake quantity is computed, and if the value of a subtraction of the computed engine speed from a current engine speed is smaller than a predetermined speed smaller than the target speed, the intake quantity increase is stopped, and fuel ignition timing is varied to bring the engine speed to the target speed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As one of internal combustion engines, a throttle valve for controlling the amount of air (intake air) sucked into a combustion chamber is provided, and fuel is supplied in accordance with the intake air amount so that the air-fuel ratio becomes a target air-fuel ratio. There is known an internal combustion engine in which fuel is injected from an injection valve into intake air. Immediately after such an internal combustion engine is started, the temperature of the internal combustion engine is low, and thus it is difficult for the fuel to burn in the combustion chamber. In such a situation, immediately after the internal combustion engine is started (engine startup), the operating state of the internal combustion engine (engine operating state) is in a so-called idling operating state in which the load required for the internal combustion engine (engine required load) is extremely small. Since the amount of fuel injected from the fuel injection valve into the intake air (fuel injection amount) is also extremely small,
The fuel is very difficult to burn in the combustion chamber, and as a result, the operation of the internal combustion engine is not stable.

Therefore, in order to avoid the instability of the operation of the internal combustion engine immediately after the engine is started, when the engine operating state is in the idling operating state (hereinafter referred to as the idling operating state after starting) immediately after the engine starting. In advance, the minimum engine speed required to stabilize the operation of the internal combustion engine is preset as the target engine speed, and when the engine speed is smaller than the target engine speed under the idling operation state after starting. Japanese Patent Application Laid-Open No. 2001-82226 discloses a technique of gradually increasing the opening of the throttle valve and thus gradually increasing the intake air amount.

Further, in this publication, when it is determined that the engine speed cannot reach the target engine speed even if the intake air amount is controlled, instead of controlling the intake air amount, ignition of fuel by a spark plug is performed. By controlling the timing, the engine speed is maintained at the target engine speed.

[0005]

By the way, in the above publication, when the engine operating state is the idling operating state after starting, in addition to controlling the intake air amount, controlling the fuel ignition timing is based on the engine speed. To reach the target engine speed as quickly as possible and to maintain the engine speed at the target engine speed as accurately as possible. As described above, in the field of the internal combustion engine, there is a demand for maintaining the engine speed at the target idle speed as accurately as possible when the engine operating state is in the idling operating state after starting. Therefore, an object of the present invention is to make the engine speed reach the target engine speed as quickly as possible and to maintain the engine speed at the target engine speed as accurately as possible under the idling operation state after starting. .

[0006]

In order to solve the above problems, in the first aspect of the invention, the reference intake air amount and the reference fuel ignition timing are predetermined according to the engine operating state. Immediately after the internal combustion engine is started, while the engine operating state is in the idling operating state, if the engine speed is smaller than the target engine speed, gradually increase the intake air amount so that the engine speed becomes the target engine speed. On the other hand, immediately after the internal combustion engine is started, while the engine operating state is in the idling operating state, if the engine speed becomes higher than the target engine speed, the intake air amount can be gradually reduced. In an internal combustion engine control system, the intake amount of the intake air that is larger than the reference intake air amount is increased immediately after the internal combustion engine is started while the engine operation state is in the idling operation state. When the engine speed is increased, the value obtained by subtracting the calculated engine speed from the current engine speed is smaller than the target engine speed and is smaller than a predetermined engine speed. The increase of the intake air amount is stopped, and the fuel ignition timing is changed so that the engine speed becomes the target engine speed.

Here, the target engine speed corresponds to the target idle speed in the embodiment described later, and the value obtained by subtracting the calculated engine speed from the current engine speed is:
In the embodiment described later, which corresponds to the substantial engine speed,
The reference intake air amount corresponds to the target intake air amount read from the map of FIG. 2 when the IS control is started in the embodiment described later.

According to this, while the engine operating state is in the idling operating state immediately after the internal combustion engine is started, the engine rotational speed is increased toward the target engine rotational speed or the engine rotational speed is set to the target engine rotational speed. Whether the intake amount should be increased or the fuel ignition timing should be changed in order to maintain the engine speed is the amount that is increased by the intake amount that is larger than the reference intake amount. The determination is made based on the value (substantial engine speed) obtained by subtracting the engine speed from the current engine speed.

By the way, also in the above publication, when the engine speed becomes smaller than a predetermined engine speed while the engine operating condition is in the idling operating condition immediately after the internal combustion engine is started, the intake air amount is reduced. By changing the fuel ignition timing instead of increasing the engine speed, the engine speed is increased toward the target engine speed. Therefore, the invention described in the above publication is the same as the invention in that it is determined based on the engine speed whether the intake air amount should be increased or the fuel ignition timing should be changed. Is.

However, in the above publication, in order to determine whether the intake air amount should be increased or the fuel ignition timing should be changed, the actual engine speed is set to a predetermined engine speed as it is. In comparison with the predetermined intake air amount, the intake air amount larger than the reference intake air amount is compared with a predetermined value. The engine speed is increased by the above, and the value obtained by subtracting the converted engine speed from the current engine speed is compared with a predetermined engine speed. Different from the present invention.

Therefore, in the above publication, a threshold value for increasing the intake air amount from the reference intake air amount is set, and then a threshold value for the engine speed is set. Here, the above publication does not specify the relationship between the threshold value for increasing the intake air amount and the threshold value for the engine speed, but when the engine operating state is in the idling state, the engine speed is the target. As long as the engine speed is maintained, even if the intake amount is relatively large, it is considered that it does not significantly affect the operation of the internal combustion engine. Should be set relatively high.

On the other hand, in the idling operation state after starting, it is presumed that if the engine speed becomes small, even if the engine speed is relatively small, the operation of the internal combustion engine may be greatly affected. The threshold value of should be set relatively close to the target engine speed.

Therefore, even if the amount of increase of the intake air amount does not exceed the threshold value and the engine speed does not fall below the threshold value, the increase of the engine speed converted from the increase amount of the intake air amount. The value obtained by subtracting the minutes from the current engine speed (real engine speed) may be very small. As described above, when the actual engine speed is extremely low, the engine speed can be quickly reached the target engine speed, or the engine speed can be accurately maintained at the target engine speed. Is preferable to change the fuel ignition timing rather than to increase the intake amount.

Therefore, according to the present invention, the engine speed quickly reaches the target engine speed, and the engine speed is accurately maintained at the target engine speed.

In the second aspect of the invention, in the first aspect of the invention, an amount that is a predetermined amount of time earlier than the reference intake amount is used. Here, it takes a certain period of time from the increase of the intake air amount to the increase of the engine speed due to the increase of the intake air amount. That is, it is more accurate to use the amount of intake air that is larger than the reference intake air amount before a certain period of time to calculate the engine speed that is increased by the intake air that is larger than the reference intake air amount more accurately. To be done. In this case, according to the present invention, since the amount that is a predetermined amount of time earlier than the reference intake amount is used as the amount of the intake amount that is greater than the reference intake amount, the intake amount of the intake amount that is greater than the reference intake amount is more accurate. The engine speed corresponding to the required amount is calculated.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 shows an overall view of an internal combustion engine including a control device according to a first embodiment of the present invention. In FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a combustion chamber, 5 is a piston, 6 is an intake port, 7 is an intake valve, 8 is an exhaust port, 9 is an exhaust valve, and 10 is The spark plug is shown. A cooling water passage 11 for cooling the internal combustion engine is formed in the cylinder block 2. Further, a water temperature sensor 12 for detecting the temperature of the cooling water in the cooling water passage 11 is attached to the cylinder block 2.

A fuel injection valve 13 is attached to the intake port 6. Further, the intake port 6 has an intake passage 1
4 is connected. A surge tank 15 is formed in the intake passage 14. A throttle valve 16 is arranged in the intake passage 14 upstream of the surge tank 15. A step motor 17 is connected to the throttle valve 16. An air cleaner 18 is arranged in the intake passage 14 upstream of the throttle valve 16. Further, an air flow meter 19 is attached to the intake passage 14 upstream of the throttle valve 16 and downstream of the air cleaner 18.

Outputs of the water temperature sensor 12 and the air flow meter 19 are input to an electronic control circuit (ECU) 20. The ECU 20 can estimate the temperature of the internal combustion engine based on the output of the water temperature sensor 12, and can calculate the amount of air (intake air) taken into the combustion chamber 4 based on the output of the air flow meter 19. On the other hand, the spark plug 10,
The fuel injection valve 13 and the step motor 17 for driving the throttle valve 16 are connected to the ECU 20, and their operations are controlled by the ECU 20. Further, the internal combustion engine has a crank angle sensor 2 for detecting a crank angle.
1, the output of this crank angle sensor 21 is ECU
It is input to 20. The ECU 20 can calculate the engine speed based on the output of the crank angle sensor 21. Further, the internal combustion engine is equipped with a load sensor 23 for detecting the load (engine required load) required of the internal combustion engine by detecting the depression amount of the accelerator pedal 22, and the output of the load sensor 23 is also output to the ECU 20. Is entered.

An exhaust passage 24 is connected to the exhaust port 8, and an oxygen sensor 25 for detecting the oxygen concentration in the exhaust gas discharged from the combustion chamber 4 is attached to the exhaust passage 24. Has been. This oxygen sensor 25
Is output to the ECU 20. The ECU 20 can calculate the air-fuel ratio in the combustion chamber 4 based on the output of the oxygen sensor 25.

In the internal combustion engine of the first embodiment, the amount of air (intake air) taken into the combustion chamber 4 is determined as the target intake air amount so that the required output can be output from the internal combustion engine. It Specifically, the target intake amount increases as the engine speed increases, and the target intake amount increases as the engine required load increases. In the first embodiment, the target intake air amount TGa is prestored in the ECU 20 in the form of a map as a function of the engine speed N and the required engine load L as shown in FIG. During operation, the target intake air amount TGa is read from the map of FIG. 2 based on the engine speed N and the engine required load L, and the amount of air taken into the combustion chamber 4 (intake air amount) is the target intake air amount. TGa
The opening degree of the throttle valve 16 (throttle opening degree) is controlled by the step motor 17 so that If the target intake air amount TGa is set large, the opening degree of the throttle valve 16 is increased. At this time, the intake air amount increases, and conversely, if the target intake air amount TGa is set small,
Since the opening degree of the throttle valve 16 is reduced, the intake amount is reduced at this time.

In the internal combustion engine of the first embodiment, the fuel injection valve 13 is injected into the intake air in accordance with the intake air amount and the target air-fuel ratio so that the air-fuel ratio in the combustion chamber 4 becomes the target air-fuel ratio. A target amount of fuel (target fuel injection amount) is determined. Specifically, the target fuel injection amount is increased as the intake air amount is increased, and the target fuel injection amount is decreased as the target air-fuel ratio increases, that is, as the lean degree of the target air-fuel ratio increases. In the first embodiment, the target fuel injection amount TGi
Is the intake air amount Ga and the air-fuel ratio A as shown in FIG.
The target fuel injection amount TGi is read from the map of FIG. 3 based on the intake air amount Ga and the air-fuel ratio A / F while the internal combustion engine is stored in advance in the form of a map as a function of / Ft. Therefore, the fuel injection valve 13 is controlled to inject fuel of the target fuel injection amount TGi from the fuel injection valve 13.
Is controlled.

Further, in the first embodiment, the spark plug 10
The timing for igniting the fuel in the combustion chamber 4 is preset as the target fuel ignition timing according to the engine operating state. In the first embodiment, the target fuel ignition timing TTi is an EC in the form of a map as a function of the engine speed N and the required engine load L as shown in FIG.
It is stored in U20 in advance, and is read from the map of FIG. 4 based on the engine speed N and the required engine load L during the operation of the internal combustion engine.

In the first embodiment, basically, the target intake air amount TGa is set as described above, and the operation of the step motor 17 for driving the throttle valve 16 is performed so that the intake air amount becomes the target intake air amount TGa. Is controlled. However,
In the first embodiment, the operating state of the internal combustion engine (engine operating state) is the depression amount of the accelerator pedal 22 until the predetermined period elapses (engine starting) from the start of the internal combustion engine (engine startup). When the engine is in a so-called idling operation state in which the required engine load is extremely small, the target intake air amount is set in a different form. Hereinafter, a method of setting the target intake air amount when the engine is started and the engine operating state is in the idling operating state (hereinafter, referred to as the post-start idling operating state) will be described.

In the idling operation state after starting, there is a minimum engine speed necessary for operating the internal combustion engine stably. However, when the engine is started, the temperature of the internal combustion engine (engine temperature) is often low,
When the engine temperature is low as described above, it is difficult for the fuel to burn in the combustion chamber 4, and the engine speed may be lower than the minimum engine speed required to stably operate the internal combustion engine. There is.

Therefore, in the first embodiment, in the idling operation state after starting, the minimum engine speed required for operating the internal combustion engine stably is the target engine speed (hereinafter referred to as the target idle speed). ) Is predetermined. Then, in the idling operation state after starting, the control described below (hereinafter, referred to as IS control) is executed. That is, in the IS control of the first embodiment,
First, the target intake air amount TGa in the post-start idling operation state is read from the map of FIG. 2, and the throttle valve 1 is adjusted so that the actual intake air amount becomes the target intake air amount TGa.
The opening degree of 6 is controlled.

Here, when the engine speed is below the target idle speed, the target intake air amount TGa is gradually corrected to the increasing side. In the first embodiment, when the target intake air amount TGa is gradually corrected to the increasing amount, the actual intake air amount gradually increases, and therefore the fuel injection amount also gradually increases, so that the engine speed gradually increases. Become.

On the other hand, in the IS control of the first embodiment, when the engine speed exceeds the target idle speed under the idling operation state after starting, the target intake air amount T
Ga is corrected to the weight reduction side. In the first embodiment, when the target intake air amount TGa is gradually corrected to the reduction amount side, the intake amount gradually decreases, and therefore the fuel injection amount also gradually decreases, so the engine speed gradually decreases.

Basically, by repeating such correction of the target intake air amount according to the IS control, the engine speed is maintained at the target idle speed under the idling operation state after the start. However, if the target intake air amount is greatly increased from the target intake air amount TGa read from the map of FIG. 2, the fuel injection amount is also increased accordingly, but here, the temperature of the internal combustion engine (engine If the temperature is low, it is difficult for the fuel to burn in the combustion chamber, so not all the fuel burns even if the fuel injection amount increases. Further, since the opening degree of the throttle valve 16 is increased when the intake amount is increased, the degree of negative pressure in the intake passage 14 downstream of the throttle valve 16 is reduced, and therefore, the injection from the fuel injection valve 13 into the intake air is performed. The injected fuel is difficult to vaporize, and a part of the fuel remains attached to the wall surface of the intake passage 14. That is, it can be said that the combustion of the fuel is deteriorated as a whole. In such a case, the fuel efficiency of the internal combustion engine will deteriorate, and even if the target intake air amount is increased, the engine speed cannot be quickly reached the target idle speed, and the increased target intake air amount is not achieved. Even if it is maintained, the engine speed will not be accurately maintained at the target idle speed. Furthermore, exhaust emission is deteriorated.

Therefore, in the IS control of the first embodiment, the engine speed is made to reach the target idle speed as quickly as possible in the idling operation state after starting, and
The following control is executed in order to maintain the engine speed at the target idle speed as accurately as possible.

That is, in the first embodiment, during execution of the IS control, the engine speed (hereinafter, referred to as the engine speed) corresponding to the intake amount larger than the target intake amount TGamn read from the map of FIG. The rotation speed increase amount) is calculated, and a value obtained by subtracting the calculated rotation speed increase amount from the current engine rotation speed calculated based on the output of the crank angle sensor 21 is calculated as the actual engine rotation speed. When the calculated actual engine speed is lower than the predetermined engine speed and the current engine speed is lower than the target idle speed, the increase of the target intake air amount is stopped and the target intake air amount is The target fuel ignition timing read from the map of FIG. 4 so that the engine speed increases toward the target idle speed while the target intake air amount is maintained at Control is adapted to be executed to be changed.

On the other hand, in the first embodiment, when the actual engine speed is lower than the predetermined engine speed during execution of the IS control and the current engine speed is maintained at the target idle speed, The target intake air amount is reduced, and the control is executed to change the target fuel ignition timing read from the map of FIG. 4 so that the engine speed is maintained at the target idle speed.

According to this, since the degree of the negative pressure in the intake passage 14 downstream of the throttle valve 16 is maintained large, the fuel injected from the fuel injection valve 13 is vaporized and dispersed in intake air at a high rate. Therefore, the engine speed is quickly reached the target idle speed, and the engine speed is accurately maintained at the target idle speed.

In the IS control of the first embodiment,
The predetermined engine speed is smaller than the target engine speed. Further, in the IS control of the first embodiment, even if the target intake air amount is increased, if the current engine speed is smaller than the predetermined engine speed, the increase of the target intake air amount is stopped and the engine is stopped. The fuel ignition timing is controlled so as to increase the rotation speed. Further, in general, the earlier the fuel ignition timing is, that is,
Since the combustion of the fuel in the combustion chamber is promoted and the engine speed increases as the position is shifted to the advance side, in the first embodiment, in order to increase the engine speed, the fuel ignition timing is set to the advance side. It is designed to be shifted.

In the first embodiment, the temperature of the internal combustion engine may also be used when determining that the engine operating state is the idling operating state after starting. That is, in addition to the condition for determining that the engine operating condition is the post-start idling operating condition in the first embodiment, a condition that the temperature of the internal combustion engine is lower than a predetermined temperature may be added.

Further, in the first embodiment, even when the current engine speed becomes lower than the predetermined engine speed, the increase of the target intake air amount is stopped, and the target intake air amount at that time is stopped. While maintaining the target intake air amount, the target fuel ignition timing read from the map of FIG. 4 is changed so that the engine speed increases toward the target idle speed.

FIG. 5 is a flow chart showing a routine for executing the IS control of the first embodiment. In the routine of FIG. 5, first, at step 10, it is judged if the idle condition is satisfied, that is, if the current engine operating state is the idling operating state after starting. When it is determined in step 10 that the idle condition is satisfied, the routine proceeds to step 1
1, the engine speed N is smaller than the predetermined idle speed Nth, which is smaller than the target idle speed (N <
Nth) or not.

When it is determined in step 11 that N <Nth, the routine proceeds to step 12, where the target intake air amount is fixed to the current target intake air amount, and the fuel ignition is performed to increase the engine speed. Timing control is performed. On the other hand, in step 11, N ≧
If it is determined to be Nth, the routine proceeds to step 13 and the engine speed ΔNi increased by the increase amount of the target intake air amount with respect to the reference target intake air amount.
Is greater than the predetermined engine speed Nth (N-ΔNi> Nt).
h) or not.

In step 13, N-ΔNi> Nt
If it is determined to be h, the routine proceeds to step 1
If the engine speed is smaller than the target idle speed, the target ignition amount remains fixed at the current target intake amount, and the fuel ignition timing control is executed to increase the engine speed. On the other hand, when the engine speed is maintained at the target idle speed, the target ignition amount is reduced and the fuel ignition timing control is executed to maintain the engine speed at the target idle speed.

On the other hand, in step 13, N-ΔNi
When it is determined that ≦ Nth, the routine proceeds to step 14, and when the engine speed is smaller than the target idle speed, the target intake air amount is increased to increase the engine speed, while the engine speed is increased. When the engine speed is maintained at the target idle speed, the current target intake air amount is maintained, while when the engine speed is higher than the target idle speed, the target intake air amount is reduced to reduce the engine speed. Reduce.

FIG. 6 is a time chart showing an example of changes in engine speed and the like when the IS control is executed according to the first embodiment. In FIG. 6, (A) shows the transition of the engine speed N, and (B) shows the target intake air amount TGa.
(C) shows the target fuel ignition timing TTi
Shows the transition of. In FIG. 6 (A), the chain line A indicates the actual engine speed.

When the internal combustion engine is started, the engine speed N once exceeds the target idle speed TN and reaches a peak, and then falls below the target idle speed TN at time t1. Substantially, the correction of the target intake air amount TGa is started from here. That is, at time t1, the engine speed N falls below the target idle speed TN, so the target intake air amount TGa is the target intake air amount T read from the map of FIG.
It is gradually increased from Gamn. And time t
After 1, the actual engine speed continues to be calculated.

Then, as shown by the chain line A in FIG. 6 (A), when the actual engine speed falls below a predetermined speed Nth at time t7, the increase of the target intake air amount TGa is stopped, and Instead, the target fuel ignition timing TT
i is gradually corrected to the advance side from the reference target fuel ignition timing TTimn read from the map of FIG. When the engine speed N reaches the target idle speed TN at time t9, the correction of the target fuel ignition timing TTi is also stopped.

By the way, the target intake air amount is increased,
Even if the actual intake amount increases, it takes a certain period of time after the target intake amount is increased until the engine speed increases due to the increase of the actual intake amount. That is, according to the first embodiment, when the actual engine speed is calculated, the increase amount of the target intake air amount at that time with respect to the reference target intake air amount represents the difference between the detected engine speed and the actual engine speed. Not not.

Therefore, in the second embodiment, the time (hereinafter referred to as the delay time) required from the increase of the target intake air amount to the increase of the engine speed due to the actual increase of the intake air amount is previously obtained by an experiment. Incidentally, when the actual engine speed is calculated while the target intake air amount is being increased, the actual engine speed is calculated in the same manner as in the first embodiment by using the target intake air amount that is a delay time earlier than the calculation time. I try to calculate the number. According to this, since the actual engine speed is calculated more accurately, the engine speed is made to reach the target idle speed more quickly, and the engine speed is maintained at the target idle speed more accurately. The Rukoto.

In the second embodiment, the delay time T
As shown in FIG. 7, d is obtained in advance in relation to the engine speed N. In FIG. 7, as the engine speed N increases, the delay time Td becomes shorter as a quadratic function.

FIG. 8 is a time chart showing an example of changes in engine speed and the like when the IS control is executed according to the second embodiment. In FIG. 8, (A),
(B) and (C) show the transition of the same parameters as in FIG. 6 (A), FIG. 6 (B), and FIG. 6 (C), respectively.

When the internal combustion engine is started, the engine speed N once exceeds the target idle speed TN and reaches a peak, and then falls below the target idle speed TN at time t1. Substantially, the correction of the target intake air amount TGa is started from here. That is, at time t1, the engine speed N falls below the target idle speed TN, so the target intake air amount TGa is the target intake air amount T read from the map of FIG.
It is gradually increased from Gamn.

Here, the delay time Td is calculated in accordance with the relationship of FIG. 7, and the actual engine speed is calculated based on the target intake air amount TGa that is the delay time Td earlier. In the example shown in FIG. 8, at time t2, the target engine intake amount TGa at time t1 is used to calculate the actual engine speed, and after time t2, the actual engine speed is similarly calculated in the same manner.

Then, as shown by the chain line A in FIG. 6 (A), at time t8, when the actual engine speed falls below the predetermined engine speed Nth, the increase of the target intake air amount TGa is stopped, Instead, the target fuel ignition timing TTi is gradually corrected to the advance side from the reference target fuel ignition timing TTimn read from the map of FIG. When the engine speed N reaches the target idle speed TN at time t9, the correction of the target fuel ignition timing TTi is also stopped.

[0050]

According to the present invention, the engine speed quickly reaches the target engine speed, and the engine speed is accurately maintained at the target engine speed.

[Brief description of drawings]

FIG. 1 is an overall view of an internal combustion engine including a control device according to a first embodiment.

FIG. 2 is a diagram showing a map used for setting a target intake air amount TGa.

FIG. 3 is a diagram showing a map used to set a target fuel injection amount TGi.

FIG. 4 is a diagram showing a map used for setting a target fuel ignition timing.

FIG. 5 is a flowchart showing a routine for executing IS control of the first embodiment.

FIG. 6 is a time chart showing changes in engine speed N and the like when IS control is executed according to the first embodiment.

FIG. 7 is a diagram showing a relationship between an engine speed N and a delay time Td in the second embodiment.

FIG. 8 is a time chart showing changes in engine speed N and the like when IS control is executed according to the second embodiment.

[Explanation of symbols]

1 ... Engine body 4 ... Combustion chamber 10 ... Spark plug 13 ... Fuel injection valve 14 ... Intake passage 16 ... Throttle valve 24 ... Exhaust passage 25 ... Oxygen sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 322 F02D 45/00 322C F02P 5/15 F02P 5/15 EF term (reference) 3G022 CA01 CA03 DA01 EA01 FA06 FA08 GA01 GA05 GA06 GA08 GA09 3G065 DA06 EA03 FA02 FA09 GA05 GA09 GA10 GA46 3G084 BA03 BA05 BA17 CA01 CA03 DA10 EA11 EB08 EB11 EC07 FA10 FA29 FA33 FA38 3G301 JA21 NE02 ND02 NE02 ND02 NC02 NE02 ND02 PD02Z PE01Z PE03Z PE08Z PF03Z

Claims (2)

[Claims] 1. A reference intake air amount and a reference fuel ignition timing are predetermined according to the engine operating state, and while the engine operating state is in an idling operating state immediately after the internal combustion engine is started. When the engine speed is lower than the target engine speed, the intake air amount is gradually increased so that the engine speed becomes the target engine speed, while the engine operating state is idling immediately after the internal combustion engine is started. When the engine speed becomes higher than the target engine speed while the engine is in the state, the intake air amount is gradually decreased. While the operating state was in the idling operating state, the engine speed that was increased by the intake amount larger than the reference intake amount was calculated, and was calculated. When the value obtained by subtracting the engine speed from the current engine speed is smaller than the target engine speed, if it is smaller than the predetermined engine speed, the intake air amount is stopped from increasing and the engine speed becomes the target engine speed. A control device for an internal combustion engine, wherein the fuel ignition timing is changed so as to be a number. 2. The control device for an internal combustion engine according to claim 1, wherein the amount of intake air that is larger than the reference intake air amount is an amount that is earlier by a predetermined time.