JP2001090581A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shortly converge a rotating speed to a target rotating speed at starting an engine. SOLUTION: An electronic control unit(ECU) 10 for an engine 1 performs the control of a rotating speed, which is either the control with an inlet air amount, that is, an engine rotating speed is controlled to a target rotating speed by regulating the opening of an electronic throttle valve 16 for the engine in response to the rotating speed at starting the engine, or the control with an ignition timing, that is, the engine rotating speed is controlled to a target rotating speed by regulating an ignition timing for the engine. The ECU 10 calculates an accumulated value for an inlet air amount for the engine from the beginning of engine starting operation (cracking) and starts the control of the rotating speed when the accumulated value reaches the capacity of an inlet air passage at the downstream side of the throttle valve 16. Therefore, the control of the rotating speed is started at the end of the sudden increase of the rotating speed due to air, staying in the inlet air passage at the downstream side of the throttle valve 16 at starting engine, inspired into the engine, making it possible to shortly converge the engine rotating speed to the target rotating speed.

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, and more particularly, to a control device for an internal combustion engine that controls the engine speed to a target speed when the engine is started.

[0002]

2. Description of the Related Art At the time of starting an engine, particularly at the time of a cold start of the engine, deterioration of combustion is likely to occur, and the engine speed may become unstable. If the combustion deteriorates, problems such as deterioration of engine startability and engine exhaust characteristics, vibrations due to instability of the rotational speed after the start, and an increase in noise occur. For this reason, various control devices have been proposed for preventing deterioration of combustion at the time of engine start and stabilizing the engine speed.

[0003] For example, as an example of this type of control device, there is one described in Japanese Patent Application Laid-Open No. Hei 5-222997.
The device of the publication discloses feedback control of the engine intake air amount and the ignition timing so that the engine speed coincides with a predetermined target speed during idling operation after the engine is started, thereby keeping the idle speed constant. I try to keep it.

[0004]

However, if the engine speed is controlled by the amount of intake air during the warm-up operation immediately after the start of the engine as in the apparatus disclosed in the above-mentioned publication, the engine is particularly operated in the idle operation after the cold start. Combustion may deteriorate. For example, in an engine equipped with a fuel injection valve that injects fuel into the engine intake port, during cold start of the engine, the injected fuel does not vaporize and remains in a liquid state on the intake port wall surface and the concentration of vaporized fuel is insufficient. It may be. In particular, when the engine is cold started or when low-volatile fuel (hereinafter referred to as "heavy fuel") is used, the amount of vaporized fuel actually sucked into the cylinder decreases because the fuel does not vaporize sufficiently. As a result, the air-fuel ratio of the air-fuel mixture may become lean and combustion may worsen. In such a case, if the opening degree of the throttle valve is increased to increase the intake air amount, the negative pressure of the intake pipe downstream of the throttle valve decreases (the absolute pressure increases).
In some cases, the fuel adhering to the wall surface is more difficult to vaporize, and the deterioration of combustion increases.

In order to solve the above-mentioned problem, the applicant of the present application has disclosed in Japanese Patent Application No. Hei 11-98897, controlling the number of revolutions at the time of starting the engine by adjusting the throttle valve opening (engine intake air amount). In addition, a control device has been proposed in which, when the engine combustion deteriorates, the rotation speed control by adjusting the throttle valve opening is stopped and switched to the rotation speed control by adjusting the engine ignition timing.

In the apparatus disclosed in the publication, the deterioration of the combustion state of the engine is determined based on the peak rotation speed and the rotation fluctuation at the time of starting the engine. By switching from the speed control by adjusting the engine ignition timing or the speed control by adjusting the throttle valve opening to the speed control by increasing the fuel injection amount, deterioration of combustion is prevented.

However, in the apparatus of the above-mentioned application, when the engine is started (in this specification, the period from the start of the engine start operation (cranking) to the steady idling operation is referred to as "the engine start"). The timing at which the control itself is started is not sufficiently considered. For example, after the start operation (cranking) is started, the engine speed rapidly rises when combustion is started in all the cylinders of the engine, and then drops again after reaching the peak speed at the start to reach a certain speed. . The engine speed control at the time of engine start requires that the engine speed converge to a predetermined target speed in a short time, but in a state where the engine speed is changing as described above after the start of the engine start operation, ,
The time until the rotation speed converges after the start of the rotation speed control differs depending on the timing of starting the rotation speed control.

Further, in the apparatus of the above-mentioned application, although the switching from the rotation speed control by adjusting the intake air amount to the rotation speed control by adjusting the ignition timing is performed depending on whether the combustion state is deteriorated, the rotation by the ignition timing adjustment after the switching is performed. Depending on the control method of the number control, there is a problem that the time required for the engine speed to converge to the target speed becomes longer. The present invention has been made in view of the above circumstances, and has as its object to provide a control device for an internal combustion engine that can converge an engine speed to a target speed in a short time when the engine is started.

[0009]

According to the first aspect of the present invention, there is provided a control device for an internal combustion engine which performs a speed control for feedback-controlling an engine speed to a predetermined target speed when the engine is started. An integrating means for integrating the engine intake air amount from the start of the engine start operation, wherein the integrated value of the intake air amount calculated by the integrating means reaches a value equal to the intake passage volume from the throttle valve to each cylinder inlet. A control device for an internal combustion engine, which starts the rotation speed control when the control is performed.

That is, according to the first aspect of the invention, when the integrated value of the engine intake air amount becomes equal to the intake passage volume on the downstream side of the throttle valve, that is, when the engine is started, it is stored in the intake passage on the downstream side of the throttle valve. From the time when the whole amount of air is sucked into the engine, the start of the rotation speed feedback control at the time of starting the engine is started. In order to converge the engine speed to the target speed in a short time when the engine is started, it is necessary to start the speed control as soon as possible. However, when the engine is started, air at atmospheric pressure is stored in the intake passage on the downstream side of the throttle valve, and when the engine start operation is started, the air stored on the downstream side of the throttle valve is independent of the throttle valve opening. Is inhaled by the engine. That is, during this time, even if the opening degree of the throttle valve is changed, the intake air amount of the engine cannot be accurately controlled, and therefore, for example, the rotation speed control by adjusting the engine intake air amount cannot be performed. Therefore, according to the present invention, the engine is started immediately after the engine start operation is started, when it is determined that the entire amount of air in the intake passage downstream of the throttle valve has been sucked into the engine, that is, when accurate rotation speed control becomes possible. The hour speed control is started. As a result, the engine speed at the time of starting the engine converges to the target speed in a short time.

According to a second aspect of the present invention, there is provided a control device for an internal combustion engine for performing a speed control for feedback-controlling an engine speed to a predetermined target speed at the time of engine start, wherein after starting the engine start operation, There is provided a control device for an internal combustion engine, comprising: means for detecting that the engine speed reaches a peak speed at the time of starting, and starting the speed control when the reaching of the peak speed is detected.

That is, according to the second aspect of the invention, when the engine speed reaches the starting peak speed after the start of the engine starting operation, the speed control is started. The peak rotation speed at the time of starting is generated because air stored in the intake passage on the downstream side of the throttle valve is immediately sucked into the engine before the engine is started. For this reason, when the engine speed reaches the starting peak speed, the entire amount of air stored in the intake passage downstream of the throttle valve is sucked into the engine, which means that accurate speed control is possible. are doing. Therefore, by starting the rotation speed control from the time when the engine rotation speed reaches the peak rotation speed at the time of starting, the engine rotation speed can be converged to the target rotation speed in a short time.

According to the third aspect of the present invention, the target rotation speed is gradually changed from the peak rotation speed to the predetermined reference rotation speed with the passage of time from the start of the rotation speed control. A control device for an internal combustion engine according to claim 2, further comprising target speed setting means. That is, according to the third aspect of the present invention, the rotation speed control is started when the rotation speed reaches the starting peak rotation speed, and the target rotation speed of the rotation speed control is changed from the peak rotation speed to the reference rotation speed (final target rotation speed). Gradually change until. In general, the peak rotation speed at the time of starting is considerably higher than the final target rotation speed of the rotation speed control (for example, the fast idle rotation speed for warming up the engine). For this reason, when the rotation speed control is started from the time when the peak rotation speed is reached, the deviation between the target rotation speed and the actual rotation speed at the start of the rotation speed control becomes large. For this reason, when the rotation speed control is started when the peak is reached, the control is performed in a direction in which the rotation speed is significantly reduced based on the deviation. However, since the engine speed naturally decreases after reaching the peak engine speed, if control is performed to greatly reduce the engine speed when the peak engine speed is reached, the engine speed will exceed the target engine speed and decrease. A chute is generated, and the convergence of the rotation speed after the start of the rotation speed control to the target rotation speed may be delayed. According to the present invention, the target rotation speed is set to the peak rotation speed at the start of the rotation speed control, and thereafter gradually changed (decreased) to the final target rotation speed with time. The deviation from the engine speed does not become excessive, and the engine speed can converge to the target engine speed in a short time by the engine speed control.

According to the fourth aspect of the present invention, the target engine speed setting means sets the deviation of the actual engine engine speed from the reference engine speed smaller than a predetermined value after the start of the engine speed control. 4. The control of the internal combustion engine according to claim 3, wherein when the deviation is larger than the case where the deviation is larger than a predetermined value, the target rotational speed is changed such that a time rate of change of the target rotational speed becomes smaller. 5. An apparatus is provided.

That is, according to the invention of claim 6, when the actual engine speed approaches the reference engine speed (final target engine speed), the change in the target engine speed is made gentle.
Thus, the engine speed smoothly converges to the final target speed without causing overshoot or undershoot. According to the fifth aspect of the present invention, there is provided a control device for an internal combustion engine that performs speed control for performing feedback control of an engine speed to a predetermined target speed at the time of engine start, and calculates a change speed of the engine speed. A control device for an internal combustion engine, comprising: means for starting the engine speed control when the calculated engine speed change speed becomes equal to or less than a predetermined value after the start of the engine start operation.

That is, according to the fifth aspect of the present invention, after the start of the engine start operation, when the change speed of the engine speed becomes equal to or less than the predetermined value, the speed control is started. As described above, the engine speed rapidly increases when combustion is started in each cylinder after the start of the engine start operation, and decreases again after reaching the start peak speed. However, even if the rotation speed control is started immediately after the start of the engine start operation, the rotation speed cannot be accurately controlled during a period in which the rate of change of the rotation speed is large before and after the peak rotation speed is reached. Hunting and the like may occur. Therefore, according to the present invention, the rotational speed control is not performed while the rotational speed around the peak rotational speed at the start after the start of the engine start operation is severe, and the time when the rotational speed control can be effectively performed, that is, the rotational speed change speed decreases. The rotation speed control is started from the point in time. As a result, the engine speed is effectively controlled from the beginning of engine speed control, and the engine speed converges to the target engine speed in a short time.

According to a sixth aspect of the present invention, there is provided a control device for an internal combustion engine for performing a speed control for feedback-controlling an engine speed to a predetermined target speed at the time of engine start, wherein after starting the engine start operation, A control device for an internal combustion engine is provided, which starts the rotation speed control when the engine rotation speed becomes equal to the target rotation speed. That is, according to the invention of claim 6, when the engine speed crosses the target engine speed when the engine speed crosses the target engine speed when the engine speed starts to decrease after passing through the engine start peak speed, the engine speed control is started. This allows
The rotation speed control is started from a state where the deviation between the target rotation speed and the actual rotation speed is small, and the engine rotation speed converges to the target rotation speed in a short time by the rotation speed control.

According to the present invention, at the time of engine start, the engine speed is controlled to a predetermined target speed by intake air speed control for performing feedback control of the engine intake air amount according to the engine speed. At the same time, it is determined whether or not the engine combustion has deteriorated at the time of starting the engine. When the combustion has deteriorated, the engine speed is adjusted to the target speed by performing feedback control of the engine ignition timing according to the engine speed from the intake air speed control. A control device for an internal combustion engine which controls the engine speed at engine start to a target engine speed by switching to an ignition timing speed control to be controlled, wherein at the start of the ignition timing speed control, a predetermined advance amount is set as compared to before the start. A control device for an internal combustion engine is provided which starts the ignition timing rotation speed control from a state where the ignition timing is advanced only by the ignition timing.

In other words, in the invention of claim 7, when the engine combustion deteriorates, the ignition timing rotation speed control is started. The control is started from. When the combustion deteriorates, the engine speed decreases greatly after the starting peak engine speed, and when the ignition timing speed control is started, the engine speed is usually much lower than the target engine speed. Therefore, by advancing the ignition timing stepwise by a predetermined amount at the start of the ignition timing rotation speed control, the actual engine rotation speed rises faster, and the ignition timing rotation speed control reduces the engine rotation speed for a short time. And converges to the target rotation speed.

According to the invention described in claim 8, there is further provided a means for detecting a start-time peak speed after the start of the engine start operation, and a means for detecting a predetermined reference peak speed and the start-time peak speed. The control device for an internal combustion engine according to claim 7, further comprising means for setting the advance amount according to the difference. That is, in the invention of claim 8, the step-like advance amount at the start of the ignition timing rotation speed control is set according to the difference between the reference peak rotation speed and the starting peak rotation speed. The starting peak rotational speed tends to decrease as the combustion deteriorates. For this reason, for example, if the normal start-time peak rotation speed at which combustion deterioration does not occur is set as the reference peak rotation speed,
The difference between the reference peak rotation speed and the starting peak rotation speed increases as the degree of combustion deterioration increases. For this reason, according to the difference between the reference peak rotation speed and the starting peak rotation speed, the step-like advance amount at the start of the ignition timing rotation speed control is set to be larger, for example, as the difference in the peak rotation speed becomes larger. Since the engine speed increasing speed after the start of the ignition timing speed control is appropriately adjusted according to the degree of combustion deterioration, the engine speed converges to the target speed in a short time.

According to the ninth aspect of the present invention, the reference peak rotational speed is further learned based on the starting peak rotational speed in the case where the ignition timing rotational speed control was not performed at the time of the previous engine start. A control device for an internal combustion engine according to claim 8, further comprising a learning unit that performs learning. That is, in the invention of claim 9, the reference peak rotational speed is learned during the actual operation. The reference peak rotational speed is a normal start-time peak rotational speed at the time of starting the engine in which deterioration of combustion does not occur.
For this reason, if the reference peak rotational speed is fixed to a constant value, the step-like advance amount at the start of the ignition timing rotational speed control may not be set appropriately. According to the present invention, the learning means sets the starting peak when the deterioration of combustion has not occurred at the time of starting the engine up to the previous time, that is, when the switching from the intake air speed control to the ignition timing speed control has not occurred. The number of revolutions is stored, and based on the starting peak number of revolutions, a reference peak number of revolutions in the current ignition timing revolution number control is set. As a result, the degree of combustion deterioration is accurately determined irrespective of individual engine differences and aging, and the step advance amount at the start of ignition timing rotation speed control is accurately set, so that the engine rotation speed is reduced. It converges to the target rotation speed in time.

According to the tenth aspect, at the time of engine start, the engine speed is controlled to a predetermined target speed by intake air speed control for performing feedback control of the engine intake air amount according to the engine speed. At the same time, it is determined whether or not the engine combustion has deteriorated at the time of starting the engine. A control device for an internal combustion engine that controls the rotation speed at engine start to a target rotation speed by switching to an ignition timing rotation speed control to be controlled. Setting means for setting a feedback control constant based on a difference between the target rotation speed and the actual rotation speed of the engine and a time change rate of the difference. Engine control device is provided.

That is, in the invention of claim 10, the value of the feedback control constant in at least one of the intake air speed control and the ignition timing speed control is determined by the difference between the target speed and the actual speed. It is set according to the time change rate of this difference. In this case, for example, if the speed control is a proportional integral (or proportional integral derivative) control including a proportional term and an integral term based on the difference between the target speed and the actual speed, the integral term is multiplied. The coefficient is set according to the rotational speed difference. For example, when the rotational speed difference is large and the rotational speed difference is increasing (that is, when the actual rotational speed is far away from the target rotational speed, In the case where the rotation speed is moving away from the target rotation speed), the coefficient of the integral term is set to a large value. As a result, the engine speed increases at a large speed. On the other hand, when the difference between the rotation speeds is small and the difference between the rotation speeds is decreasing (that is, when the actual engine rotation speed is close to the target rotation speed, and the rotation speed further approaches the target rotation speed). In such a case, the coefficient of the integral term is set to a small value. As a result, the engine speed approaches the target speed at a moderate speed, so that the engine speed smoothly converges to the target speed without overshoot or the like.

According to the eleventh aspect of the present invention, of the intake air speed control and the ignition timing speed control, at least the speed control for setting the feedback control constant by the setting means is the actual speed control. A proportional integral derivative control based on a proportional amount proportional to a deviation of the number from the target rotation speed, an integral amount that is a time integral value of the deviation, and a derivative amount that is a time differential value of the deviation. 10. A control device for an internal combustion engine according to 10 is provided.

That is, in the eleventh aspect of the present invention, at least the rotational speed control for setting the feedback control constant by the method of the tenth aspect is a proportional integral derivative control.
Thus, for example, by setting the coefficient of the integral term in the proportional integral derivative control in accordance with the difference between the target rotational speed and the actual rotational speed and the rate of change of the difference, the engine rotational speed can be set to the target rotational speed in a short time and smoothly. It comes to converge on the rotation speed.

According to the twelfth aspect, at the time of engine start, the engine speed is controlled to a predetermined target speed by intake air speed control for performing feedback control of the engine intake air amount in accordance with the engine speed. At the same time, it is determined whether or not the engine combustion has deteriorated at the time of starting the engine. A control device for an internal combustion engine that controls the rotation speed at engine startup to a target rotation speed by switching to controlled ignition timing rotation speed control, and further promotes temperature rise of an exhaust purification catalyst arranged in an engine exhaust passage at engine startup. Therefore, the ignition timing is retarded by a predetermined catalyst warm-up delay amount as compared to after the catalyst temperature rise, and the catalyst warm-up delay amount becomes zero after a predetermined time has elapsed from the start of the engine start operation. Catalyst warm-up means for changing the catalyst warm-up retard amount so that the catalyst warm-up means is shorter when the ignition timing speed control is performed than when the ignition timing speed control is not performed. A control device for an internal combustion engine is provided that changes the catalyst warm-up retard amount so that the catalyst warm-up retard amount becomes zero with time.

That is, according to the twelfth aspect of the present invention, there is provided catalyst warm-up means for retarding the ignition timing for raising the temperature of the catalyst when the engine is started. On the other hand, if the deterioration of the combustion occurs and the ignition timing speed control is executed, the engine ignition timing is advanced to prevent the engine speed from decreasing due to the deterioration of the combustion. For this reason, when the combustion deteriorates, the ignition timing retarding operation by the catalyst warm-up means and the ignition timing advancement operation by the ignition timing rotational speed control may be performed at the same time. Control and control may interfere with each other, and the time required to converge the engine speed to the target speed may increase. In the present embodiment, when the ignition timing rotation speed control is performed, the catalyst warm-up delay amount decreases earlier to zero when the ignition timing rotation speed control is not performed than when the engine is normally started. Next, the catalyst warm-up retard amount is changed. This prevents the catalyst warm-up operation from interfering with the ignition timing rotation speed control, so that the engine rotation speed converges to the target rotation speed in a short time.

According to the thirteenth aspect, when the engine is started, the engine speed is controlled to a predetermined target speed by an intake air speed control for performing feedback control of the engine intake air amount according to the engine speed. At the same time, it is determined whether or not the engine combustion has deteriorated at the time of starting the engine. A control device for an internal combustion engine that controls the rotation speed at engine start to a target rotation speed by switching to controlled ignition timing rotation speed control, further promoting the temperature rise of an exhaust purification catalyst disposed in an engine exhaust passage at engine start Catalyst warm-up means for delaying the ignition timing by a predetermined catalyst warm-up delay amount compared to after the catalyst temperature rise, and means for detecting the starting peak rotational speed after the start of the engine start operation. Wherein the catalyst warm-up means, wherein the ignition timing engine speed control conducted, the catalyst warm-up delay amount as compared with the case where the rotation speed control ignition timing is not being performed,
A control device for an internal combustion engine is provided, which is set to be smaller by an amount corresponding to a difference between a predetermined reference peak rotation speed and the starting peak rotation speed.

That is, in the invention of claim 13, the catalyst warm-up retard amount is set to a small value in order to prevent the interference between the catalyst warm-up operation and the ignition timing rotation speed control, as in the case of claim 12. I do. At this time, the catalyst warm-up retard amount is set to be smaller by an amount corresponding to the difference between the reference peak rotational speed and the starting peak rotational speed. As described above, the difference between the reference peak speed and the starting peak speed changes according to the degree of deterioration of combustion. Further, when the degree of combustion deterioration is large (that is, when the peak rotational speed difference is large), the ignition timing advance amount in the ignition timing rotational speed control becomes large.
For this reason, in the present invention, the catalyst warm-up retard amount is greatly reduced as the peak rotational speed difference is larger, and the ignition timing advance in the ignition timing rotational speed control is affected by the catalyst warm-up retard amount. I try not to. This prevents the catalyst warm-up operation from interfering with the ignition timing speed control,
The engine speed converges to the target speed in a short time.

According to the fourteenth aspect, at the time of engine start, the engine speed is controlled to a predetermined target speed by intake air speed control for performing feedback control of the engine intake air amount according to the engine speed. At the same time, it is determined whether or not the engine combustion has deteriorated at the time of starting the engine. A control device for an internal combustion engine that controls the rotation speed at engine start to a target rotation speed by switching to controlled ignition timing rotation speed control, further promoting the temperature rise of an exhaust purification catalyst disposed in an engine exhaust passage at engine start. A catalyst warm-up means for retarding the ignition timing by a predetermined catalyst warm-up delay amount compared to after the catalyst temperature rises, wherein the catalyst warm-up means is provided when the ignition timing rotation speed control is performed. A control device for an internal combustion engine, wherein the catalyst warm-up retard amount is set to be smaller according to a feedback correction amount of the ignition timing in the ignition timing rotation speed control as compared with a case where the ignition timing rotation speed control is not performed. Is provided.

That is, in the fourteenth aspect of the present invention, the reduction of the catalyst warm-up delay amount during the execution of the ignition timing rotation speed control is set according to the feedback correction amount of the ignition timing rotation speed control.
When the rotation speed is greatly reduced due to the deterioration of combustion, the feedback correction amount of the ignition timing in the ignition timing rotation speed control is set to be large, and the ignition timing is advanced. In this case, if the catalyst warm-up retard amount is large, the ignition timing cannot be advanced sufficiently, and the required increase in the rotational speed cannot be obtained. In the present invention, the catalyst warm-up delay amount is set in accordance with the feedback correction amount of the ignition timing, for example, when the feedback correction amount is large, the catalyst warm-up delay amount is significantly reduced, so that the catalyst is warmed up. The warm-up operation is prevented from interfering with the ignition timing speed control. Therefore, the engine speed converges to the target speed in a short time without being affected by the catalyst warm-up operation.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the entire configuration when the present invention is applied to an internal combustion engine for a vehicle. In FIG. 1, 1 is an internal combustion engine main body, 2 is a surge tank provided in an intake passage of the engine 1, 2a is an intake manifold connecting the surge tank 2 and an intake port of each cylinder, 1
Reference numeral 6 denotes a throttle valve arranged in an intake passage on the upstream side of the surge tank 2, and reference numeral 7 denotes a fuel injection valve for injecting pressurized fuel into an intake port of each cylinder of the engine 1.

In the present embodiment, the throttle valve 16 is provided with an actuator 16a such as a stepper motor or the like, and has an opening degree corresponding to a control signal input from the ECU 10 described later. That is, as the throttle valve 16 of the present embodiment, a so-called electronically controlled throttle valve that can take an opening irrespective of the accelerator pedal operation amount of the driver is used. Also, throttle valve 1
6 is provided with a throttle opening sensor 17 for generating a voltage signal corresponding to the operation amount (opening) of the throttle valve.

In FIG. 1, reference numeral 11 denotes an exhaust manifold for connecting the exhaust port of each cylinder to a common collective exhaust pipe 14;
Is a three-way catalyst disposed in the exhaust pipe 14, 13 is an upstream air-fuel ratio sensor disposed at an exhaust confluence portion (upstream of the three-way catalyst 20) of the exhaust manifold 11, and 15 is an exhaust pipe downstream of the three-way catalyst 20. 14 is a downstream air-fuel ratio sensor arranged at 14. The three-way catalyst 20 can exhaust air-fuel ratio flowing to purify HC in the exhaust gas when in the vicinity of the stoichiometric air-fuel ratio, CO, three components of the NO _X at the same time. The air-fuel ratio sensors 13 and 15 are used for exhaust air-fuel ratio detection when performing feedback control of the fuel injection amount to the engine so that the engine air-fuel ratio becomes a predetermined target air-fuel ratio during normal operation of the engine.

In this embodiment, an intake pressure sensor 3 for generating a voltage signal corresponding to the intake pressure (absolute pressure) in the surge tank is provided in the surge tank 2 in the intake passage.
The water jacket 8 of the cylinder block is provided with a water temperature sensor 9 for generating an analog voltage electric signal corresponding to the temperature of the cooling water. The output signals of the throttle valve opening sensor 17, the intake pressure sensor 3, the water temperature sensor 9, and the air-fuel ratio sensors 13 and 15 are provided by ECUs described later.
It is input to the A / D converter 101 with a built-in multiplexer.

Reference numerals 5 and 6 in FIG. 1 denote crank angle sensors disposed near the camshaft and the crankshaft (not shown) of the engine 1, respectively. For example, the crank angle sensor 5 generates a reference position detection pulse signal every 720 ° in terms of a crank angle, and the crank angle sensor 6 generates a crank angle detection pulse signal every 30 ° of the crank angle. The pulse signals of these crank angle sensors 5 and 6 are
The output of the crank angle sensor 6 is supplied to the CPU 103 of the ECU 10.
Is supplied to the interrupt terminal. The ECU 10 calculates the rotational speed (rotational speed) of the engine 1 based on the crank angle pulse signal interval from the crank angle sensor 6 and uses it for various controls.

Electronic control unit (ECU) 10 of engine 1
Is configured as a microcomputer, for example, and includes an A / D converter 101 with a built-in multiplexer, an input / output interface 102, a CPU 103, a ROM 104,
A RAM 105, a backup RAM 106 capable of holding data even when the main switch is turned off, a clock generation circuit 107, and the like are provided.

The ECU 10 performs basic control of the engine 1 such as fuel injection amount control and ignition timing control of the engine 1 on the basis of the intake pressure, the throttle valve opening and the engine speed. At the start of the engine (from the start of cranking to the steady idle operation after the complete explosion), the engine speed at the start is controlled to maintain the engine speed at the target speed. In order to perform the above control, the ECU 10 executes an A / D conversion routine that is executed at regular intervals to execute the intake pressure (P
M) signal, throttle opening (TA) signal from the throttle opening sensor 17, cooling water temperature (T
HW) signal is A / D converted and input.

The input / output interface 102 of the ECU 10 is connected to the fuel injection valve 7 via a drive circuit 108, and controls the amount and timing of fuel injection from the fuel injection valve 7. Further, an input / output interface 102 of the ECU 10 is connected to each ignition plug 111 of the engine 1 through an ignition circuit 110, controls the ignition timing of the engine, and is connected to an actuator 16a of the throttle valve 16 through a drive circuit 113. Then, the opening of the throttle valve 16 is controlled by driving the actuator 16a.

Next, the rotation speed control at the time of starting according to the present embodiment will be described. In the present embodiment, the ECU 10 sets the engine speed to a predetermined target during engine start, that is, from the start of the engine start operation (start of cranking) to the start of stable idling after completion of engine warm-up. Start-up speed control is performed to maintain the speed (generally, a fast idle speed for promoting warm-up of the engine). Normally, at the start of engine cranking, the fuel injection amount of the engine is set to an amount obtained by adding a correction according to the intake air temperature (atmospheric temperature) and the atmospheric pressure to the basic start-up injection amount determined from the coolant temperature and the engine speed. You. After the cranking is started, the engine speed is higher than the cranking speed by a predetermined speed (for example, 400 rpm).
After that, after the combustion is started in each cylinder and the engine is determined to be in a complete explosion state, the fuel injection amount is the basic fuel according to the engine intake air amount and the engine speed. The injection amount is set to an amount obtained by multiplying the injection amount by a predetermined coefficient. The basic fuel injection amount is a fuel injection amount required to maintain the engine combustion air-fuel ratio at the stoichiometric air-fuel ratio. The above-mentioned predetermined coefficient is for compensating the adhesion of the injected fuel to the intake port wall surface at the time of engine start and the deterioration of the fuel vaporization state due to the low temperature, and the predetermined coefficient is larger than 1 at the time of engine start. And the engine combustion air-fuel ratio is set to be richer than the stoichiometric air-fuel ratio.

When the engine is started, the temperature of the exhaust purification catalyst (indicated by reference numeral 20 in FIG. 1) arranged in the exhaust passage is low, and the catalyst cannot exhibit the exhaust purification function. Therefore,
After the engine is started, it is necessary to raise the catalyst temperature to the activation temperature as soon as possible to start the exhaust gas purification by the catalyst. For this reason, at the time of normal engine startup, the engine ignition timing is retarded as compared with the normal operation in order to raise the exhaust gas temperature and raise the temperature of the catalyst in a short time.

As described above, the fuel injection amount at the time of starting the engine is appropriately set in accordance with various factors. Therefore, if the engine is normally in a normal state, the rotation speed fluctuation due to deterioration of combustion at the time of starting the engine hardly occurs. Has become. However, even when the engine is normal, there is a case where the rotation speed fluctuates due to deterioration of combustion at the time of starting. For example, if the properties of the fuel (gasoline) used for the engine are different, combustion deterioration at the time of starting is likely to occur. The fuel injection amount at the time of starting the engine is set based on the case where a fuel having a standard property is used. Therefore, for example, when a fuel having a lower volatility than the standard fuel (hereinafter, referred to as "heavy fuel") is used in the engine, combustion may be deteriorated particularly at the time of cold start of the engine. That is, since the heavy fuel has low volatility, even when the same amount of fuel as the standard fuel is injected, the ratio of the fuel adhering to the intake port wall as a liquid without vaporization increases and is actually supplied into the cylinder. The amount of fuel used is reduced. As a result, the combustion air-fuel ratio of the engine shifts to a leaner side than normal, and the engine speed becomes unstable due to deterioration of combustion.

Generally, as a method of preventing the engine speed from becoming unstable at the time of starting and maintaining the engine speed at a predetermined target speed, feedback control of the engine intake air amount based on the engine speed (intake air amount) Rotation speed control) is performed. In the intake amount rotation speed control, when the engine rotation speed is lower than the target rotation speed, the opening of the throttle valve 16 is increased (the engine intake air amount is increased) to increase the rotation speed, and the rotation speed is higher than the target rotation speed. In this case, the rotation speed is maintained at the target rotation speed by performing feedback control based on the rotation speed by reducing the opening degree of the throttle valve (reducing the intake air amount) to reduce the rotation speed. However, when heavy fuel is used, deterioration of combustion of the engine cannot be suppressed by intake air speed control, and the start speed may not be maintained at the target speed.

For example, in the case where the combustion air-fuel ratio of the engine becomes a lean air-fuel ratio at the start of the engine due to the use of heavy fuel and combustion deteriorates, in the intake air speed control, if the engine speed decreases due to the combustion deterioration, the engine speed is reduced. The throttle valve opening is increased to increase the number. However, if the opening degree of the throttle valve is increased, the negative pressure in the intake passage downstream of the throttle valve decreases (the absolute pressure increases), so that the injected fuel becomes more difficult to vaporize. For this reason, the engine combustion air-fuel ratio may shift further in the lean direction, and the deterioration of combustion may increase.

In the present embodiment, when it is determined that the intake amount rotation speed control cannot compensate for the decrease in the startup rotation speed due to the deterioration of combustion, the ignition timing rotation speed control is performed instead of the intake amount rotation speed control. In addition, even when combustion deteriorates, the engine speed is accurately maintained at the target speed. In the ignition timing rotation speed control, an operation of maintaining the engine rotation speed at the target rotation speed by performing feedback control of the ignition timing based on the engine rotation speed is performed. When the engine is started, the engine ignition timing is retarded for warming up the catalyst as described above. On the other hand, when heavy fuel is used, the combustion speed of the in-cylinder air-fuel mixture decreases due to a lean air-fuel ratio or the like. Therefore, by advancing the engine ignition timing to compensate for the decrease in combustion speed, the output torque in the cylinder increases, and the engine speed increases. As a result, even when heavy fuel is used and engine combustion deteriorates, the engine speed can be accurately matched with the target engine speed.

It should be noted that, when the ignition timing rotation speed control is performed, the ignition timing is generally advanced as compared with the case where the ignition timing rotation speed control is not performed, so that the engine exhaust temperature becomes low and the catalyst warm-up is delayed. Become. For this reason, in the present embodiment, at the time of engine start, the intake amount rotation speed control is first performed, and only when the combustion deterioration is determined, the switching from the intake amount rotation speed control to the ignition point mechanical point control is performed. It suppresses deterioration of engine exhaust characteristics due to delay of warm-up.

Further, the method of judging deterioration of combustion used in the present invention is not particularly limited, and any method may be used as long as it can accurately judge deterioration of combustion. For example, after the engine start operation (cranking) is started, when combustion is started in all the cylinders of the engine (that is, when the engine is completely exploded), the engine speed rapidly rises and reaches the start-time peak speed. , Then decline. The start-time peak rotational speed decreases as the degree of deterioration of engine combustion increases (the volatility of the fuel used decreases). For this reason, the starting peak rotation speed when combustion deterioration does not occur (when using normal fuel having good volatility) is set in advance as the reference peak rotation speed, and the actual starting peak rotation speed is set. Is lower than the reference peak rotational speed by a predetermined value or more, it is possible to determine that combustion has deteriorated. In addition, when it is determined that the combustion deterioration has occurred, the ignition timing speed control may be started immediately without performing the intake air speed control at the time of starting the engine. At the start, the intake air speed control is performed first,
Thereafter, when it is determined that the intake speed cannot be maintained at the target rotation speed in the intake air speed control (for example, when the intake air amount feedback correction amount in the intake air speed control increases beyond a predetermined value), the ignition timing rotation speed is increased. The control may be switched.

In the case where the engine speed control at the start is performed by the intake air speed control and the ignition timing speed control as described above, the start timing of the engine speed control at the start and the setting of the control parameters at the start are problematic. Becomes That is, in the engine speed control at the time of starting, it is desirable that the engine speed converge to the target engine speed corresponding to the fast idle speed in as short a time as possible after the start of the engine start operation. However, depending on the timing of the control start and the setting of the control parameters at the start of the control, conversely, there is a problem that the rotation speed fluctuation increases and the speed following the target rotation speed decreases, and the convergence to the target rotation speed is delayed. . For example, as will be described later, after the start of the engine start operation, the engine speed cannot be generally controlled until the engine speed reaches the peak speed. For this reason, if the engine speed control was started simultaneously with the start of the engine start operation,
Not only cannot accurate rotation speed control be performed, but also the feedback correction amount of the intake air amount and the ignition timing is set to an excessively large value by the rotation speed control. The fluctuation may be large. Further, when the actual engine speed is in the region near the target speed at the start of the speed control, if the control parameters such as the feedback control gain are set to a large value, the speed overshoot and underspeed may occur. Shooting may occur and delay in convergence to the target rotational speed may occur.

In the starting speed control of the present invention described below, the engine speed can be smoothly controlled by appropriately setting the timing of starting the speed control or the control parameters in the speed control at the start of the control. It is possible to converge on the target rotational speed in a short time. Hereinafter, a specific embodiment of the start-time rotational speed control of the present invention will be described. (1) First Embodiment In this embodiment, after starting the engine start operation (cranking), the rotation speed control is started from the time when the amount of air taken into the engine becomes equal to the intake passage volume downstream of the throttle valve. By doing so, the timing of the start of the rotation speed control is appropriately set, and the engine rotation speed smoothly converges to the target rotation speed in a short time after the start of the control.

FIG. 2 is a diagram showing a general time change of the engine speed when the engine is started with the opening of the throttle valve 16 kept constant. As shown in FIG. 2, the engine speed increases after the start of cranking, and when an explosion occurs in all cylinders, the engine speed rapidly increases and reaches a peak speed (point a in FIG. 2). Then, after reaching the peak rotation speed, the engine rotation speed again decreases and becomes the idle rotation (point b).

In FIG. 2, although the throttle valve 16 is kept constant, the rotation speed sharply rises at the time of starting and the peak rotation speed occurs for the following reason. That is, when the engine is stopped, the intake passage pressure downstream of the throttle valve 16 is equal to the atmospheric pressure, and a relatively large amount of air is stored in the intake passage between the throttle valve 16 and each cylinder. When the engine starts rotating, the air stored downstream of the throttle valve is sucked into the cylinder at once. For this reason, at the start of the engine start operation, a large amount of air is sucked into the cylinder in the same manner as when the throttle valve is fully opened, and the engine speed rapidly rises with the complete combustion of the engine. However, after the entire amount of the air stored on the downstream side of the throttle valve is drawn into the cylinder, only the amount of air corresponding to the opening of the throttle valve is supplied into the cylinder, so that the rotation speed decreases. For this reason, after the start of the engine start operation, the engine speed temporarily rises suddenly, and a peak speed at the start occurs.

As described above, in order to match the engine speed to the target speed at an early stage, it is desirable to start the speed control as early as possible. However, during the start of the engine, while the air stored in the intake passage downstream of the throttle valve is being sucked into the cylinder, it is the same as if the throttle valve is kept fully open, so that the intake air speed control, It is difficult to control the rotation speed by any of the ignition timing rotation speed controls. In addition, when the rotation speed control is started at this time, the intake air amount rotation speed control and the ignition timing rotation speed control reduce the rotation speed so that the intake air amount is significantly reduced or the ignition timing is greatly retarded. I will proceed. For this reason, after reaching the peak rotation speed at the time of starting, when the rotation speed decreases, the rotation speed drops significantly from the target rotation speed,
There is a problem that the convergence to the target rotational speed is delayed.

In the present embodiment, the amount of air sucked into the engine after the start of the engine start operation is integrated, and the rotation speed control is started when the integrated value reaches the intake passage volume downstream of the throttle valve. The above problem has been solved. That is, after the amount of air stored in the intake passage on the downstream side of the throttle valve is sucked into the engine at the start of the engine start operation,
The engine speed can be controlled by the speed control. Therefore, in the present embodiment, it is determined from the integrated value of the intake air amount of the engine that an amount of intake air equal to the amount stored on the downstream side of the throttle valve has been sucked into the engine, and the rotation speed control is started from that time. . Thus, since the rotation speed control can be started immediately after the rotation speed control becomes possible after the start of the engine start operation, it is possible to converge the engine rotation speed to the target rotation speed in a short time.

FIG. 3 is a flowchart for explaining the starting operation of the start-time rotational speed control of the present embodiment. This operation is
This is performed as a routine executed by the ECU 10 at regular intervals. When the operation of FIG. 3 starts, step 3
In 01, the engine speed NE and the throttle valve opening THA detected by the corresponding sensors 6 and 17 are read. In step 303, the above NE and THA
The current intake volume efficiency η _V is calculated based on The volumetric efficiency η _V is a ratio between the amount of air actually taken into the engine and the total exhaust amount of the engine, and is a function of the throttle valve opening THA and the engine speed NE. In the present embodiment, the relationship between the value of η _V and THA, NE is obtained by actually operating the engine while changing the throttle valve opening and the engine speed in advance and actually measuring the engine intake air amount. The value of η _V is stored in the ROM 104 of the ECU 10 as a numerical table using THA and NE. In step 303, the value of the volumetric efficiency η _V is read from the numerical value table based on the throttle valve opening THA and the rotational speed NE.

Next, at step 305, the integrated value of the amount (volume) of air actually sucked into the engine is calculated as (η _V × V _d /
2) It is increased by × NE × K _T. Here, η _V is the intake volume efficiency calculated in step 303, V _d is the engine displacement, NE is the engine speed (RPM), and K _T is K _T = ΔT /
A constant represented by 60. ΔT is the execution interval (second) of this operation. That is, in the present embodiment, since the engine 1 is a four-cycle engine, the amount of air to be taken per rotation of the engine is represented by (η _V × V _d / 2). NE × _KT indicates how many revolutions of the engine have been made since the last execution of this operation and before the execution of this operation. Therefore,
The value of _{(η V × V d / 2} ) × NE × K T will represent the air amount drawn into the previous present operation execution after the engine (volume). Since the initial value of the value of ΣQ is set to 0, by executing step 305 every fixed time (ΔT), Σ
The value of Q accurately represents the integrated value of the engine intake air amount up to the present.

[0056] By the above, after calculating the accumulated value [sum] Q, the current value of the intake air amount integrated value [sum] Q In step 307, whether the host vehicle has reached the predetermined value V _vol is determined. Where V _vol
Is the total volume of the intake passage downstream of the throttle valve 16. If ΣQ <V _vol in step 307, that is, since the entire amount of air stored on the downstream side of the throttle valve 16 has not been sucked into the engine, accurate rotation speed control cannot be performed. This operation ends as it is. Further, when ΔQ ≧ V _vol , the entire amount of air stored downstream of the throttle valve is sucked into the engine, and accurate rotation speed control can be performed. For this reason,
In this case, the process proceeds to step 309, in which the value of the rotation speed control execution flag FB is set to 1, and the operation ends.

When the flag FB is set to 1, E
The routine executed by the CU 10 permits the above-described intake air speed control and ignition timing speed control, and executes the intake air speed control or the ignition timing speed control if combustion is deteriorating. Is done. (2) Second Embodiment Next, another embodiment of the starting operation of the engine speed control at engine start according to the present invention will be described. Also in the present embodiment, as in the first embodiment, the rotation speed can be converged to the target rotation speed in a short time by starting the control at the same time as the control of the rotation speed becomes possible, in the first embodiment. Although the control start timing is determined based on the intake air amount, the present embodiment is different in that the control start timing is determined based on the engine speed.

As described above, after the start of the engine start operation, while the air stored downstream of the throttle valve is being sucked into the engine, the engine speed increases regardless of the throttle valve opening degree, and After the entire amount is sucked into the engine, the engine speed drops to a speed corresponding to the throttle valve opening. Therefore, when the engine speed starts to decrease, that is, when the engine speed reaches the starting peak speed described in FIG. 2, the entire amount of air stored downstream of the throttle valve is sucked into the engine. It can be considered that the time.

Therefore, in the present embodiment, the engine speed is monitored after the engine start operation is started, and the speed control is started from the time when it is determined that the engine speed has reached the peak speed at the time of starting. . FIG. 4 and FIG. 5 are flowcharts for explaining the rotation speed control start operation of the present embodiment. FIG.
After the start operation of the engine is started, a flowchart showing a detection operation for detecting that the engine speed has reached the start peak speed, and FIG. 5 shows a start speed control start operation based on whether or not the start peak speed has been reached. It is a flowchart. 4 and 5 are performed by routines executed by the ECU 10 at regular intervals.

In the operation of FIG. 4, first, at step 401, it is determined whether or not the value of the peak detection flag FP is set to 1. The peak detection flag FP is a flag that is set to 1 in step 415 described later when the engine speed reaches the peak speed at the time of starting. The initial value is 0.
Is set to If the value of the peak detection flag FP is set to 1 in step 401, it is not necessary to perform peak detection again, so this operation ends without executing step 403 and subsequent steps.

If FP # 1 at step 401, that is, if peak detection has not been completed, then step 403 is executed.
In step 405 and step 407, it is determined whether the current peak detection condition is satisfied. In the present embodiment, the peak detection operation is the engine speed NE is higher than a predetermined value NE _S, is performed only (step 405), and when the engine starting operation starts after a predetermined time has passed (step 407) You. These conditions are for preventing erroneous detection of the starting peak rotational speed. That is, the combustion of the engine is not stabilized before the engine is completely exploded, and the engine speed fluctuates without increasing uniformly, so that a small peak may occur in the engine speed. In the present embodiment, in order to prevent the erroneous detection of the small rotational speed peak as the start timing peak rpm, the engine speed is higher than a predetermined value NE _S (NE _S is determined to engine is in complete combustion state The detection of the peak rotation speed is started after a lapse of a predetermined time (for example, 1000 ms) after the start operation is started. Step 40
If one or both of the conditions 5 and 407 are not satisfied, the operation immediately ends without executing Step 409 and the subsequent steps.

If the conditions of Steps 405 and 407 are satisfied, the routine proceeds to Step 409, where the engine speed NE _i-1 at the previous execution of the operation and the current engine speed NE read at Step 403 are calculated. To compare. And NE ≧
If it is NE _i−1, that is, if the engine speed is currently increasing, the operation of replacing the value of the starting peak speed NEP with the engine speed NE measured this time (step 4).
11) and NE for the next execution of this operation
Update the value of _i-1 and end this operation.

On the other hand, if NE <NE _i−1 in step 409, that is, if the engine speed has started to decrease after reaching the starting peak speed, step 415
To set the value of the peak detection flag FP to 1 and end the operation. As a result, while the engine speed continues to increase, the peak engine speed NEP is updated using the current engine speed.
Is not updated, the peak rotational speed at the time of starting is set in NEP. Also, once the start-time peak rotation speed is detected, the peak detection flag FP is set to 1
, The peak detection operation will not be performed from next time (step 401).

In the operation of FIG. 5, first, at step 501, it is determined whether or not the engine is currently idling. Whether or not the engine is currently idling is determined based on whether or not the throttle valve opening THA is set to a predetermined opening during idling. If the engine is currently idling, it is determined in step 503 whether the value of the peak detection flag FP set by the operation in FIG. 4 is 1 (detected). If FP = 1, it means that the engine speed has reached the peak engine speed at the time of starting, so the process proceeds to step 505, and the engine speed control execution flag F
Set B to 1 and end the operation. Thereby, the first
In the same manner as in the embodiment, the intake air amount rotation speed control (or ignition timing rotation speed control) is executed. On the other hand, if FP ≠ 1, since the peak rotation speed at the start has not yet been reached and it is not time to start the rotation speed control, the value of the rotation speed control flag FB is not changed. The operation ends as it is.

If the engine is not currently idling at step 501, that is, if the vehicle is currently running, there is no need to start the rotation speed control, so this operation ends immediately. According to the present embodiment, it is possible to easily determine the start timing of the rotation speed control without calculating the integrated value of the intake air amount. (3) Third Embodiment Next, a third embodiment of the present invention will be described.

In the present embodiment, similar to the second embodiment,
When the engine speed reaches the starting peak speed, the speed control starts.However, at the start of the speed control, the control target speed is set to the actual peak speed. The speed is changed to the final target speed (fast idle speed). When the rotation speed control is started when the starting peak rotation speed is reached, the rotation speed at the start of the control is considerably higher than the fast idle rotation speed. For this reason, if the fast idle speed is set as the target speed from the start of the control, the speed control is performed in the direction of decreasing the actual speed in the speed control. On the other hand, since the engine speed naturally decreases after reaching the peak speed, if control is performed in this direction to significantly reduce the engine speed, the engine speed will greatly decrease beyond the fast idle speed. In some cases, it takes time to converge to the final target rotation speed, that is, the fast idle rotation speed. Therefore, in the present embodiment, when starting the rotation speed control when the starting peak rotation speed is reached, the control target rotation speed is set to the actual startup peak rotation speed, and then the control target rotation speed is gradually reduced to the final rotation speed. An operation is performed to reduce the speed to the fast idle speed which is the target speed. As a result, a large deviation does not occur between the actual engine speed and the control target speed even after the peak engine speed has been reached, so that control for drastically reducing the engine speed is not performed, and the engine speed is quickly reduced after the start of the control. The number converges to the target speed.

In this embodiment, when the engine speed falls within a predetermined value from the fast idle speed while the engine speed is falling from the peak speed at the time of starting, that is, when the engine speed approaches the final target speed while the speed is falling. Then, an operation is performed to further reduce the rate of decrease in the control target rotation speed. As described above, by reducing the rate of decrease of the control target rotation speed near the final target rotation speed, the occurrence of undershoot when the rotation speed decreases is further suppressed.

FIG. 6 is a flowchart specifically illustrating the target rotation speed setting operation of the present embodiment. This operation is
This is performed by a routine executed by the ECU 10 at regular intervals. When the operation starts in FIG. 6, in step 601, it is determined whether or not the current rotational speed control execution flag FB is set to 1. If FB ≠ 1, this operation is immediately performed without executing steps 603 and subsequent steps. To end.

On the other hand, if FB = 1 in step 601, it is determined in step 603 whether or not the current operation is executed first after the value of the flag FB changes from 0 to 1, and Only when this is the first execution after the value change, the step 605 is executed to set an initial value of a variable KNE to be described later. Also in this embodiment, the operations in FIGS. 4 and 5 are separately performed, and the value of FB is set to 1 at the same time when the engine reaches the starting peak rotational speed. The flag X in steps 603 and 607 is set to 1 immediately after the value of FB changes from 0 to 1 in step 605.
This is a flag used to execute only once.

In step 605, the initial value of KNE is
It is set as KNE = NEP-NE _0. Where N
EP is the actual start-time peak rotation speed at the time of starting the engine this time, and is set by the operation of FIG. NE ₀ is a final target rotation speed (fast idle rotation speed) of the rotation speed control. As will be described later, in the present embodiment, the target rotational speed of the rotational speed control is set such that TNE is NE ₀ + KNE, and KN
The value of E decreases with time from the initial value.

Steps 613 and 615 are KNE reduction operations. In the present embodiment, it is determined whether or not the actual engine speed NE has approached the final target value NE ₀ , that is, NE is equal to NE +
Changing the rate of decrease KNE depending on whether it is [Delta] NE ₁ below. That is, in step 611, the rotational speed NE
Is determined to be equal to or less than NE ₀ + ΔNE ₁ , and N
If E> NE ₀ + ΔNE ₁ (when the actual rotation speed is not close to the final target value), the value of KNE is reduced by a relatively large constant value K ₁ every time the operation is executed (step 613).
This causes the value of KNE to decrease with time at a relatively high rate. In step 611, NE ≦ NE ₀ +
ΔNE ₁ (when the actual speed approaches the final target value)
Relatively the value of KNE every operation performed in small constant value K ₂
(K ₂ <K ₁ ) at a time (step 615). As a result, the value of KNE decreases with time at a relatively high speed from the start of the control until the value approaches the final target value, and changes so that the decreasing speed decreases when the value approaches the final target value. The value of [Delta] NE ₁ in this embodiment is set to, for example, a constant value of about 100 RPM.

Then, in step 617, the target rotational speed TNE in the rotational speed control is set as TNE = NE ₀ + KNE. When the value of KNE becomes negative due to the decrease, the value of TNE becomes the final target rotational speed NE _0.
(Steps 609 and 619). According to the operation of FIG. 6, in this embodiment, when the rotation speed control is started when the peak rotation speed at the time of starting is reached, the control target rotation speed TNE
Is set to the actual peak rotational speed NEP (step 60).
5,617), followed to the final target rotational real rotational speed to speed approaches decreases relatively large rate with time (step 611 and 613), the actual rotational speed has approached the final target rotational speed NE ₀ region Then, the speed decreases at a relatively small speed (step 615), and becomes equal to the final target rotational speed NE ₀ (steps 609 and 619).

Although the operation of FIG. 6 is executed at regular intervals by the ECU 10, if the operation of FIG. 6 is executed at a constant rotation angle of the engine crankshaft, the control target rotational speed is additionally provided. Is changed according to the engine speed, so that the control responsiveness can be further improved. In the present embodiment, by gradually changing the control target rotation speed from the actual peak rotation speed to the final target rotation speed as described above, even when the actual start-time peak rotation speed varies, the control target rotation speed is controlled. There is no large deviation between the rotational speed and the actual rotational speed, and the engine rotational speed can be made to converge to the final target rotational speed in a short time.
Further, in the present embodiment, when the actual engine speed approaches the final target speed, the change speed of the control target speed is set to a small value. The convergence time to numbers is further reduced. (4) Fourth Embodiment Next, a fourth embodiment of the present invention will be described.

In the above-described first to third embodiments, after the engine start operation is started, the rotation speed control is started when the rotation speed becomes near the starting peak rotation speed. For this reason, at the start of the rotation speed control, the actual rotation speed is higher than the target rotation speed (for example, the fast idle rotation speed), and when the rotation speed control is started, the intake air amount or the ignition timing decreases in the rotation speed. Will be corrected. However, in practice, when the engine is started, the rotational speed rapidly decreases after reaching the peak rotational speed. For this reason, if the rotation speed control is started when the rotation speed suddenly decreases after reaching the peak rotation speed, the rotation speed may be excessively reduced and the convergence to the target rotation speed may be delayed.

Therefore, in the present embodiment, the engine speed change speed after the start of the engine start operation is detected, and the speed control is started when the change speed becomes equal to or less than a predetermined value.
The engine speed converges to the target speed in a short time. FIG. 7 is a flowchart illustrating a start-time rotational speed control start operation according to the present embodiment. This operation is performed by the ECU
This is performed by a routine executed at regular intervals by the routine 10.

FIG. 7 shows steps 701 to 705 for judging whether or not the condition for starting the rotational speed control is satisfied. That is, in step 701, it is determined whether or not the engine is currently idling based on the opening degree of the throttle valve 16.
At 03, it is determined whether or not the rotation speed control has already been started based on the rotation speed control execution flag FB. In step 705, the current engine start operation (cranking) is performed.
It is determined whether a predetermined time (for example, about 2000 ms) has elapsed after the start. If it is not the idling operation in step 701 or if the rotation speed control has already been started in step 703 (FB = 1), it is not necessary to start the rotation speed control further, so that the operations after step 707 are executed. This operation ends immediately without doing so. Step 705
If the predetermined time has not elapsed after the start of the engine start operation, there is a possibility that the engine speed has not yet reached the start-time peak speed. In this case, in order to avoid detecting a decrease in the rotational speed change speed near the starting peak rotational speed, the operation is similarly terminated without executing the steps 707 and subsequent steps.

If all of the conditions in steps 701 to 703 are satisfied, the flow proceeds to step 707 where the current engine speed N
E, and the rotational speed change speed RNE from the rotational speed NE _i-1 at the time of the previous operation execution to the present time is RNE = | NE-N
It is calculated as E _i-1 |. Then, in step 711, the value of NE _i-1 is updated in preparation for the next RNE calculation operation, and the process proceeds to step 713.

In step 713, it is determined whether or not the rotational speed change speed calculated in step 711 has become equal to or less than a predetermined value RNE _0. If RNE ≦ RNE ₀ , the value of the rotational speed control execution flag FB is determined. Is set to 1.
Thus, in the present embodiment, the rotation speed control is started from the point in time when the speed of change of the rotation speed is reduced, and the rotation speed converges to the target rotation speed in a short time. (5) Fifth Embodiment Next, a fifth embodiment of the present invention will be described.

In the present embodiment, when the engine speed decreases after passing through the starting peak speed after the engine start operation is started, the speed control is started from the time when the target speed is crossed. . As described above, the engine speed rapidly decreases after the start peak speed. For this reason, if the rotation speed control is started from a state where the rotation speed is still higher than the target rotation speed after passing the peak rotation speed, the rotation speed control further decreases the rotation speed even though the engine rotation speed is decreasing. This causes the rotation speed to be excessively reduced.

In this embodiment, when the engine speed crosses the target engine speed (fast idling engine speed) during the fall after reaching the peak engine speed, that is, from the time when the actual engine speed becomes equal to the target engine speed. By starting the rotation speed control, an excessive decrease in the rotation speed is prevented.
That is, in the present embodiment, at the start of the rotation speed control, the difference between the actual rotation speed and the target rotation speed is extremely small, so that the actual rotation speed is not drastically reduced. For this reason, the rotation speed at the start of control is prevented from being excessively reduced, and the rotation speed converges to the target rotation speed in a short time.

FIG. 8 is a flowchart for explaining the rotation speed control start operation according to this embodiment. This operation is performed by the ECU 1
This is performed by a routine executed at regular intervals of 0. FIG. 8, steps 801 and 803 correspond to FIG.
The determination as to whether or not the rotational speed control start condition is the same as in the case of 01 and 703 is shown. Step 805 shows a determination as to whether or not the current rotational speed has passed the starting peak rotational speed. FP
Is a peak detection flag set by an operation similar to that of FIG. Step 8
If FP ≠ 1 at 05, that is, if the rotational speed has not reached the peak rotational speed at the time of starting, the rotational speed control is started when the engine rotational speed matches the target rotational speed during the rotational speed increase. To prevent this, the operations after step 807 are not executed.

[0082] If it is after the current peak rotational speed passes at step 805, reads the rotational speed NE in step 807, determines whether the decreased rotational speed NE read in step 809 is less than the target rotational speed NE ₀ I do. And
If NE ≦ NE ₀ , the value of the rotation speed control execution flag FB is set to 1 in step 811 and the operation ends. Thus, when the engine speed drops to the target speed after passing through the peak speed at the time of starting, the speed control is started.

If it is determined in step 809 that the engine speed NE has not yet decreased to the target speed NE ₀ , the process proceeds to step 813, where a predetermined time (for example, about 3000 ms) has elapsed since the start of the engine start operation. If the predetermined time has elapsed, it is determined whether or not the engine speed has not decreased to the target speed in step 8.
The program proceeds to step 11 to start the rotation speed control. This is because if the decrease in the engine speed after the start-up peak has reached a relatively gentle level, it takes a relatively long time for the engine speed to decrease to the target speed, and thus the engine speed will decrease to the target speed. This is because the rotation speed control is started without waiting for the rotation speed to quickly converge the rotation speed to the target rotation speed. In this case, since the decrease speed of the engine speed is relatively slow, even if the engine speed control is started before the engine speed decreases to the target engine speed, no significant decrease in the engine speed occurs. (6) Sixth Embodiment Next, a sixth embodiment of the present invention will be described.

In this embodiment, when switching from the intake air amount rotation speed control to the ignition timing rotation speed control when the combustion of the engine deteriorates, the ignition timing rotation speed control is performed in a state where the ignition timing is advanced by a predetermined amount stepwise. I'm trying to get started. Normally, when the combustion deteriorates, the rotation speed decreases after reaching the peak rotation speed. Therefore, at the time when the switching from the intake air amount rotation speed control to the ignition timing rotation speed control is performed when the engine combustion deteriorates, the engine rotation speed is higher than the target rotation speed. It is lower. For this reason,
After switching to ignition timing speed control, it is necessary to increase the speed at an early stage.

Therefore, in the present invention, when switching to the ignition timing rotation speed control, the ignition timing rotation speed control is started with the ignition timing advanced by a predetermined amount as compared to before the switching. As a result, the engine speed increases simultaneously with the start of the ignition timing speed control, and reaches the target speed in a short time. The operation of switching the rotation speed control when the combustion of the engine deteriorates, the operation of controlling the rotation speed of the intake air, and the operation of controlling the rotation speed of the ignition timing when the combustion of the engine deteriorates will be specifically described below with reference to FIGS.

In this embodiment, it is determined whether the engine combustion has deteriorated by comparing the starting peak rotational speed NEP detected by the operation of FIG. 4 with a predetermined reference peak rotational speed NEP _0. I do. When engine combustion worsens,
The starting peak rotation speed NEP decreases according to the degree of combustion deterioration. For this reason, for example, an appropriate reference peak rotational speed NE
If P ₀ (constant value) is set in advance and the difference DNP (= NEP ₀ −NEP) between the reference peak rotation speed NEP ₀ and the actual start-time peak rotation speed NEP is calculated, the degree of combustion deterioration Is larger, the value of DNP is larger. Therefore, the degree of combustion deterioration can be represented using the value of DNP.

In this embodiment, at the start of the rotation speed control,
First, the intake air speed control is performed, the presence / absence of combustion deterioration is determined based on the value of the peak speed difference DNP, and switching from the intake air speed control to the ignition timing control is performed according to the degree of combustion deterioration. The time is set. FIG. 9 is a flowchart illustrating the starting rotation speed control operation of the present embodiment. This operation is performed as a routine executed by the ECU 10 at regular intervals.

When the operation is started in FIG. 9, it is determined in step 901 whether or not the engine is currently idling, and in step 903, it is determined whether or not the value of a rotation speed control execution flag FB is 1. If the engine is currently idling and the value of the rotation speed control execution flag FB is set to 1 (execution), the process proceeds to step 905, where the predetermined reference peak rotation speed NEP ₀ and the operation of FIG. The difference DNP from the start-time peak rotation speed NEP detected in step (1) is calculated. Then, in step 907, the upper limit value EQ _MAX of the feedback correction amount EQ of the intake air amount rotation speed control is set according to the value of DNP, and the operation ends.

On the other hand, if any one of the conditions in steps 901 and 903 is not satisfied, the routine proceeds to step 909, where the values of the intake air speed control execution flag CN and the ignition timing speed control execution flag IN are both set to 0. To end the operation. In the present embodiment, when the intake amount rotation speed control execution flag CN is set to 1, the intake amount rotation speed control described later is executed, and when the ignition timing rotation speed control execution flag IN is set to 1, the ignition timing rotation speed is set. Control is executed. The initial value of the intake air speed control execution flag CN is set to 1 (execution). Therefore, when the value of the flag FB is set to 1 during the idling operation (step 901,
903) First, the intake air amount control is started.

FIG. 10 is a flowchart for explaining the intake air speed control operation. In this operation, the target rotational speed NE
_{The value of} the intake air amount feedback correction amount EQ is set based on the difference DNE between ₀ and the actual engine speed NE. The value of the feedback correction amount EQ is the switching to the ignition timing engine speed control from the intake air quantity engine speed control to reach the upper limit EQ _MAX is performed.

That is, in step 1001, it is determined whether or not the value of the intake air speed control flag CN is 1 (executed). If CN = 1, steps 1003 and 100 are executed.
5, the value of DNE is calculated, and in step 1007, the integral value IDNE of the deviation DNE is calculated. In step 1009, the differential value DDNE of the deviation DNE is calculated as DDN
It is calculated as E = DNE-DNE _i-1 . DNE _i-1
Is the value of DNE at the time of the last execution of this operation. The value of DNE _i-1 is updated in step 1011 every time the operation is performed.

Then, at step 1013, the value of the feedback correction amount EQ of the intake air amount is equal to EQ = α ₁ × DNE.
+ Α ₂ × IDNE + α ₃ × DDNE.
That is, the value of the feedback correction amount EQ is set by proportional differential integration control based on the difference DNE between the target rotation speed and the actual rotation speed. After the value of the correction amount EQ is set as described above, it is determined in step 1015 whether or not the value of the correction amount EQ has reached the upper limit value EQ _MAX set in the operation of FIG. 9. In step 101
7 and the target value QT of the engine intake air amount becomes QT = Q
Calculated as _CAL + EQ. Q _CAL is a target intake air amount determined by the engine speed and the driver's accelerator pedal depression amount. In step 1019, the opening of the throttle valve 16 is controlled in accordance with the calculated engine intake air amount QT.

If the feedback correction amount EQ has reached the upper limit value EQ _MAX in step 1015,
Proceeding to step 1021, the intake air speed control execution flag C
The value of N is set to 0 (stop), and the value of the ignition timing speed control flag IN is set to 1 (execute). Accordingly, the intake air speed control is stopped from the next time (step 1001), and the ignition timing speed control described later is started. That is, switching from the intake air speed control to the ignition timing speed control is performed.

In this embodiment, the feedback correction amount EQ
Is switched to the ignition timing rotation speed control when reaches the upper limit value EQ _MAX for the following reason. That is,
When the ignition timing speed control is performed, the ignition timing is generally advanced, so that the exhaust gas temperature decreases and it takes time to increase the temperature of the exhaust purification catalyst. Therefore, when the switching to the ignition timing speed control is performed, the engine operation time in a state where the exhaust purification catalyst does not reach the activation temperature becomes longer,
As a whole, the exhaust properties at the start of the engine tend to deteriorate. In this embodiment, the rotation speed control is performed by the intake air amount rotation speed control as much as possible to prevent the deterioration of the exhaust properties, and the ignition timing is set only when it is determined that the rotation speed cannot be controlled by the intake air amount rotation speed due to deterioration of combustion. Switching to rotation speed control is performed. For example, when the engine speed deteriorates due to deterioration of engine combustion and the engine speed decreases below the target engine speed, the feedback correction amount EQ is set to be increased in the intake air speed control to increase the engine speed. The value of EQ is the integral term ID
By the action of NE, the engine speed NE continues to increase as long as the actual engine speed NE is lower than the target engine speed. For this reason, when the value of EQ reaches a certain large value, it can be determined that it is difficult to control the engine speed to the target speed by the intake air speed control. Therefore, in the present embodiment, when the EQ value reaches a certain upper limit value EQ _MAX , it is determined that the decrease in the rotational speed due to the deterioration of the combustion cannot be recovered by the intake air rotational speed control, and the ignition timing rotational speed control is performed. Is switched.

Further, as described above, in the present embodiment, the value of the upper limit value EQ _MAX is set according to the value of the peak rotation speed difference DNP (FIG. 9, step 90).
7). FIG. 11 is a diagram showing the E set in step 907 of FIG.
It is a figure showing the value of _QMAX . As shown in FIG.
The value of _MAX is set to a relatively large positive constant value EQ _MAX0 in the region where DNP is a negative value (when the engine startup peak rotation speed NEP is higher than the reference rotation speed NEP ₀ ). Also EQ
The value of _MAX is reduced as DNP is larger in the region of DNP is a positive value, 0 in the DNP is a predetermined value DNP ₁ or more
Is set to

As described above, the value of DNP indicates the degree of combustion deterioration. The larger the value of DNP, the worse the combustion. For this reason, in the present embodiment, as the degree of deterioration of combustion increases, the value of the upper limit value EQ _MAX is set to be small, so that the timing of switching from intake air speed control to ignition timing speed control is advanced. Also, DNP
Is larger than the predetermined value DNP ₁ , that is, if it is determined that the deterioration of combustion is considerably large, the upper limit EQ
_Since the value of _MAX is set to 0, switching from the intake air speed control to the ignition timing speed control is performed immediately after the start of the speed control.

Next, a description will be given of the ignition timing rotation speed control operation of the present embodiment. In the present embodiment, when the switching from the intake air speed to the ignition timing speed control is performed as described above, the target engine speed NE ₀ is the same as in the intake air speed control.
The feedback correction amount of the ignition timing is set by the proportional-integral-differential control based on the difference DNE between the ignition timing and the actual rotational speed NE. However, in this embodiment, ignition timing in addition to the ignition timing rotational speed control of the feedback correction amount is started is advanced by a predetermined amount K _3. When the rotation speed control is switched from the intake air rotation speed control to the ignition timing rotation speed control, when the deterioration of the combustion occurs, the engine rotation speed decreases in accordance with the deterioration of the combustion. Therefore, when the ignition timing rotation speed control is started, it is necessary to significantly advance the ignition timing to increase the engine rotation speed to the target rotation speed. In this case, there is a possibility that the increase in the rotational speed may be delayed if the control waits until the ignition timing feedback correction amount increases by the feedback control based on the rotational speed difference.
Therefore, in this embodiment, when the ignition timing engine speed control is started, and the ignition timing is uniformly compared to before the start irrespective of the engine speed to be advanced by a predetermined value K _3. Thus, the engine speed increases simultaneously with the start of the ignition timing speed control, and converges to the target speed in a short time.

FIG. 12 is a flowchart for explaining the ignition timing rotation speed control operation of this embodiment. This operation is E
This is performed as a routine executed by the CU 10 at regular intervals. In FIG. 12, when the operation starts, in step 1201, the ignition timing rotation speed control execution flag IN
Is determined whether or not the value of is set to 1. This operation is executed only when the value of the flag IN is set to 1. As a result, as soon as the value of the flag IN is set to 1 by the intake air speed control operation of FIG. 10, switching from the intake air speed control to the ignition timing speed control is performed.

In steps 1203 to 1207, FIG.
0, as well as from step 1003 1009, the difference between the actual rotational speed NE and the target revolving speed NE ₀ DNE, and DNE
Is calculated as the integral value IDNE and the derivative value DDNE. Further, in the present embodiment, the engine ignition timing AOP is the above-mentioned DNE,
Using IDNE and DDNE, AOP = EA _CAL + K ₃ + β ₁ × DNE + β ₂ × IDN
Set as E + β ₃ × DDNE-EACAT. Then, in step 1215, the ignition timing AOP set as described above is set in the ignition circuit 110, and this operation ends.

In the above equation, the ignition timing AOP is represented by the crank angle up to the top dead center of each cylinder, and the ignition timing advances as the value of AOP increases. EA _CAL is the basic ignition timing determined from the engine coolant temperature, β ₁ , β ₂ ,
β ₃ is a coefficient (feedback control constant) of a proportional term, an integral term, and a differential term, respectively. K ₃ is a positive predetermined value,
EACAT is a catalyst warm-up retard amount. Catalyst warm-up retard amount E
ACAT will be described later.

As described above, the feedback correction amount (β ₁ × DNE + β ₂ × I
DNE + β ₃ × DDNE) is set by proportional-integral-derivative control based on the difference DNE between the target rotational speed and the actual rotational speed. In the ignition timing control, the basic ignition timing EA _CAL
Advance amount K ₃ is different is that it is added uniformly to.

[0102] That is, when the ignition timing rotational angle control is started, the ignition timing compared to before the start will be advanced by K ₃ stepwise. As a result, the speed at which the rotational speed increases increases, and the engine rotational speed converges to the target rotational speed NE ₀ in a short time. It will be described step advance amount K ₃ at the start of the ignition timing. Step advance amount K ₃ may be set as a constant value, but in the present embodiment, so as to set the value of K ₃ according to the degree of deterioration of the combustion. In other words, the greater the degree of combustion deterioration, the greater the decrease in engine speed at the start of ignition timing speed control, and it is necessary to set the speed at which the speed increases. In the present embodiment, the degree of deterioration of combustion, i.e. as the value of the peak rotational speed difference DNP is set to a large value of the step advance amount K ₃ the larger, and accelerating the increase in the rotational speed.

FIG. 13 shows the step advance amount K of this embodiment.
FIG. ₃ is a diagram showing a relationship between ₃ and a peak rotational speed difference DNP. As shown in FIG. 13, step advance amount K ₃ is set to 0 in the DNP value is negative region, linearly increases between the value of the DNP are from 0 to a predetermined value DNP _2, DNP values Is DN
The P ₂ or more regions is set to be a constant value. Thus, the step advance amount K ₃ is to be set to a larger value the larger the deterioration of the combustion.

Next, the reference peak rotational speed NEP ₀ used for calculating DNP will be described. As for the value of NEP _0, the peak rotation speed at startup when combustion deterioration has not occurred is measured in advance by experiment, and this peak rotation speed at startup is stored in the ROM of the ECU 10 as the reference peak rotation speed NEP _0. May be. However, the peak rotation speed at the start may vary from engine to engine due to individual differences of the engines and changes in internal friction due to aging. Therefore, in the present embodiment, the peak rotation speed N at the start detected every time the engine is actually started.
The reference peak rotational speed NEP ₀ is set based on the EP.

That is, the ECU 10 stores the peak rotational speed NEP detected at the start of the engine in the RAM, and sets the value of the ignition timing rotational speed control execution flag IN to 1 at the time when the engine warm-up is completed and the normal operation is started. It is determined whether or not ignition control has been performed at the time of starting the engine this time. If the ignition timing speed control is not executed at the time of starting the engine this time, it can be determined that the deterioration of combustion has not occurred at the time of starting this time. Therefore, in this case, the starting peak rotation speed stored at the time of the current start is adopted as the value of the reference peak rotation speed NEP ₀ , and the backup R
Stored in AM and used for the next engine start operation. If the ignition timing speed control is executed at the time of the current engine start, the reference peak speed NEP ₀ up to the previous time is not updated and used for the next engine start operation. This makes it possible to accurately determine the deterioration of engine combustion even when the internal friction changes or the like for each engine or due to aging. (7) Seventh Embodiment Next, a seventh embodiment of the present invention will be described.

In the sixth embodiment, the intake air speed control and the ignition timing speed control are proportional integral differential control based on the difference DNE between the target speed NE ₀ and the actual speed NE. Proportional term α ₁ × DNE, β ₁ × DNE, integral term α
₂ × IDNE, β ₂ × IDNE and differential term α ₃ × DDN
The values of E, β ₃ × DDNE coefficients (feedback control constants) α ₁ , α ₂ , α ₃ , and β ₁ , β ₂ , β ₃ were fixed to constant values. In contrast, in the present embodiment, the value of the feedback control constant is set according to the rotational speed difference DNE and the rate of change DDNE.

For example, when the engine speed is significantly lower than the target speed and the difference DNE from the target speed is increasing, the feedback correction amount is required to greatly increase the speed. (Α ₁ × DNE + α ₂ × I
DNE + α ₃ × DDNE), (β ₁ × DNE + β ₂ × I
DNE + β ₃ × DDNE) must be greatly increased.

On the other hand, when the engine speed is approaching the target engine speed, the value of the engine speed difference DNE is relatively small, and the engine speed difference DNE
If the NE is decreasing, an overshoot may occur with respect to the target rotation speed unless the rising speed of the rotation speed is set to a small value. Therefore, the feedback correction amount needs to be set small. In this case, if the feedback control constant is fixed to a constant value, the feedback correction amount is not always set to the optimum value, and the convergence to the target rotation speed may be delayed.

In this embodiment, the value of the feedback control constant is set in accordance with the rotational speed difference DNE and its increasing / decreasing tendency (that is, the differential value of the DNE, DDNE), so that the feedback correction amount changes in accordance with the changing tendency of the rotational speed. Thus, the time required for the rotational speed to converge to the target rotational speed is further reduced by setting the optimal value. In the present embodiment, the integral term coefficients α ₂ and β ₂ among the feedback control constants are changed according to the actual rotational speed change tendency. Since the integral term is an integrated value of the rotational speed difference, the change of the integral term itself is relatively small even if the rotational speed difference changes. For this reason, the change tendency of the rotational speed is less likely to be reflected in the integral term than in the proportional term and the differential term. Therefore, when the feedback control constant is changed in accordance with the rotational speed change tendency, the integral term coefficient may be changed in accordance with the rotational speed change tendency to increase the degree of reflection of the rotational speed change tendency in the integral term. This is because it is most effective in shortening the convergence time of the rotation speed.
Naturally, a greater effect can be obtained by changing the proportional term and the differential term in accordance with the rotational speed change tendency.

First, the integral term in the present embodiment will be described. In the sixth embodiment, the integral term IDNE is calculated as the integrated value of the rotational speed difference DNE ΣDNE, and the constants α ₂ , β
Multiplied by _two . That is, in the case of the intake air amount rotation speed control in FIG. 10, the feedback correction amount EQ is
(1) EQ = α ₁ × DNE + α ₂ × IDNE (= ΣDN
E) It was calculated as + α ₃ × DDNE. On the other hand, in the present embodiment, the integral term IDNE is previously calculated by multiplying DNE by α ₂ at the time of integration, and is calculated as Σ (α ₂ × DNE).
(2) EQ = α ₁ × DNE + IDNE (= Σ (α ₂ × D
NE)) + α ₃ × DDNE. Equations (1) and (2) are identical when α ₂ is a constant value.

However, in this embodiment, the value of the integral term coefficient α ₂ is changed in accordance with the value of the rotational speed difference DNE and the rate of change DDNE. As a result, the tendency of the change in the rotation speed is more appropriately reflected in the integral term. That is, the value of α ₂ is set in accordance with the values of DNE and DDNE, but in the present embodiment, in practice, the optimum α ₂ (in the case of ignition timing rotation speed control, the optimum α ₂ according to each combination of DNE and DDNE) Is β ₂ )
Is set by an experiment or the like, and a value QIDNE (= α ₂ × DNE) obtained by multiplying DNE by α ₂ is set to DNE and DDNE.
ROM 104 of the ECU 10 in the form of a numerical map using
It is stored in. Then, using the values of DNE and DDNE calculated each time the operation of FIG. 10 is performed, QIDNE (= α ₂ × DNE) is obtained from this numerical map as the increase / decrease amount of the integral term.
Is read, and the value of the feedback correction amount EQ is calculated by using the above equation (2) to obtain EQ = α ₁ × DNE + IDNE (=
(ΣQIDNE) + α ₃ × DDNE.

FIG. 18 shows the variation QIDNE of the integral term.
FIG. 7 is a diagram illustrating setting of a value of (= α ₂ × DNE). FIG.
, The horizontal axis represents the rotational speed difference DNE (= NE ₀ −NE)
And the vertical axis indicates the side or the ratio DDNE. Also, in FIG. 18, the straight line N ₁ is a rotational speed difference DNE =
0 (the state in which the target rotational speed and the actual rotation speed are matched), the straight line N ₂ is DDNE = 0 represents (engine speed are stable state), respectively. Further, as will be described later, the straight line I is in a state where QIDNE = 0. In the present embodiment, the straight line I is provided as a straight line that passes through the points of DNE = 0 and DDNE = 0 and that has a slope of 45 degrees to the right.

Now, in FIG. 18, DNE <0 and DNE
Consider a case where DNE <0 (point A in FIG. 18). In this case, since it is _{DNE (= NE 0 -NE) <} 0, the engine speed NE is higher than the target rotational speed NE _0, moreover DDNE <rotational speed difference since it is 0 the large negative than the previous Value. That is, in this case, it means that the rotation speed is already higher than the target rotation speed, but the rotation speed is further increasing. For this reason, in this case, it is necessary to decrease the value of the integral term IDNE to decrease the value of the feedback correction amount EQ. Therefore,
In the present embodiment, in such a case, the integral term variation QID
As the value of NE (= α ₂ × DNE) becomes negative and the rotational speed difference DNE is a large negative value (the rotational speed is high), and the change rate DDNE is a negative large value (the rotational speed is larger). The value of α ₂ is set so that the QIDNE becomes a large negative value as the number increases rapidly.

On the other hand, when DNE> 0 and DDNE> 0 (point B in FIG. 18), the rotational speed is lower than the target rotational speed, and the rotational speed difference is increasing (ie, the rotational speed is decreasing). . Therefore, in this case, it is necessary to increase the value of the integral term IDNE quickly to increase the value of the feedback correction amount EQ. Thus, in this case, the integral term variation Q
The value of IDNE (= α ₂ × DNE) becomes positive, and the larger the rotational speed difference DNE is (the lower the rotational speed), and the larger the change rate DDNE is the positive positive value (the rotational speed). The value of α ₂ is set so that the QIDNE becomes a large positive value as the number decreases rapidly.

Next, consider the case of point C and point D in FIG. In this case, both DNE <0, DDNE>
0, which is a state where the rotation speed is higher than the target rotation speed but the difference in rotation speed is decreasing (the rotation speed is decreasing). In this case, it is necessary to change the sign of QIDNE according to the size of DNE and DDNE. For example, at point C in FIG.
Since the value of DNE is a relatively large negative value, the rotational speed is much higher than the target rotational speed. For this reason,
Although the number of revolutions tends to decrease, it is preferable that the rate of decrease of the number of revolutions is slightly increased so that the number of revolutions reaches the target number of revolutions quickly. Therefore, in this case, QIDN
The value of E is set to a relatively small negative value. On the other hand, since the value of DNE is a relatively small negative value at point D, the rotation speed is higher than the target rotation speed but relatively close to the target rotation speed. In addition, since DDNE> 0, the difference in the number of revolutions is decreasing (the number of revolutions is decreasing). For this reason, if the value of IDNE is still large, overshoot may occur, and the rotational speed may exceed the target rotational speed and decrease. Therefore, at point D, the value of QIDNE is set to a relatively small positive value, and the value of IDNE is gradually increased.

In the same manner as described above, points E and F (DNE
> 0, DDNE <0), the value of QIDNE is set to a relatively small negative value at point E and to a relatively small positive value at point F. At the point on the straight line I in FIG. 18, the rotational speed difference DNE and the change tendency DDNE of the difference are shown.
Since the effects of the above are offset each other, the value of the integral term IDNE is not increased or decreased and the previous value is held as it is. Therefore, QIDNE = 0 is set at a point on this line. For this reason, the straight line I is a boundary line between a region where QIDNE becomes positive and a region where QIDNE becomes negative. In the present embodiment, in order to stabilize the control, an area within a certain distance from the straight line I (an area indicated by oblique lines in FIG. 18) is provided, and in this area, the value of QIDNE is set to 0, and DNE and IDNE
The value of IDNE is prevented from increasing or decreasing even when the value of?

As described above, in the present embodiment, the QIDN
The value of E (= α ₂ × DNE) takes a positive value in the upper part of the hatched area in FIG. 18 and a negative value in the lower part thereof. It will be set to be. In this way, by setting the value of the feedback control constant (α ₂ , β ₂ ) in accordance with the rotational speed difference DNE and the rate of change DDNE thereof every time the operation is performed, the feedback correction amount can be adjusted according to the tendency of the rotational speed to change. Thus, the convergence time of the rotation speed to the target rotation speed is shortened. (8) Eighth Embodiment Next, an eighth embodiment of the present invention will be described.

In this embodiment, the ignition timing rotation speed control is executed.
To adjust the ignition timing retard amount for warming up the catalyst during
From the ignition timing control and the ignition timing for warming up the catalyst
Prevents interference with the retard angle and sets the engine speed to the target speed in a short time
Let it converge. As described with reference to FIG.
During the control, the engine ignition timing AOP is determined from the engine coolant temperature.
Basic ignition timing EA_CAL(In the example of FIG. 12, EA_CAL+
K_Three) And the amount of feedback correction (β in the example of FIG. 12).₁×
DNE + β_Two× IDNE + β _Three× IDNE)
Set as the amount to which the warming-up machine retard angle (-EACAT) is added.
It is. The catalyst warm-up retard amount EACAT is determined by the exhaust
Raise the temperature to bring the exhaust purification catalyst to the activation temperature in a short time
Provided after the engine has started
After gradually increasing, then gradually decreasing and after starting operation
It changes so that it becomes 0 after a lapse of a predetermined time.

In practice, the catalyst warm-up retard amount EACAT is
EACAT = RF × EACAT _BASE .
Here, EACAT _BASE is a basic catalyst warm-up retard amount,
It is given in advance as a function of the engine cooling water temperature. Also, R
F is a reflection coefficient, which is given as a function of time from the start of the engine start operation. FIG. 14 is a diagram showing a time change after the start of the engine start operation of RF.

As shown in FIG. 14, the reflection coefficient RF is set to 0 in order to facilitate the engine start from the start of the engine start operation to a predetermined time t ₁ , and starts to increase several seconds after the start of the start operation. I do. Then, when RF = 1 is increased, the decrease is gradually started thereafter, and is set to decrease to 0. Therefore, the catalyst warm-up retard amount EACA
T also changes in the same manner as shown in FIG. 14 after the start of the engine start operation. However, since the ignition timing rotation speed control changes the engine ignition timing to match the rotation speed with the target rotation speed, if the catalyst warm-up delay amount EACAT increases or decreases during the ignition timing rotation speed control, the rotation speed increases. Adjustment of the ignition timing by numerical control and increase / decrease of EACAT interfere with each other, and it may not be possible to converge the engine speed to the target speed in a short time.

Therefore, in this embodiment, when the ignition timing rotation speed control is started, the catalyst warm-up retard amount EACAT
The (reflection coefficient RF) is rapidly attenuated to zero to prevent the ignition timing retard for warming up the catalyst from interfering with the ignition timing rotation speed control. FIG. 15 is a flowchart illustrating a catalyst warm-up retard amount control operation of the present embodiment. This operation is performed as a routine executed by the ECU 10 at regular intervals.

In this operation, when the ignition timing retard control is not executed, the value of EACAT is changed to EACA as usual.
Although T = RF × EACAT _BASE is set, when the ignition timing retard control is started, the setting of the catalyst warm-up retard amount EACAT by the above equation is stopped, and the retard amount EA is set.
The CAT is reduced by a fixed amount from the current value to 0. That is, in the present embodiment, when the ignition timing rotation speed control is not executed, the catalyst warm-up retard amount EACAT is set to the value shown in FIG.
However, when the ignition timing speed control is started at the point S in FIG. 14, for example, the catalyst warm-up retard amount EACAT decreases linearly as shown by the dotted line in FIG. , And is controlled to be 0 in a shorter time than when the ignition timing speed control is not executed.

That is, when the operation is started in FIG. 15, in step 1501, it is determined from the value of the ignition timing rotation speed control execution flag IN whether or not the ignition timing rotation speed control is currently being executed. And if IN ≠ 1,
That is, if the ignition timing rotation speed control is not currently being executed, the routine proceeds to step 1503, where the catalyst warm-up retard amount EA
Set CAT as EACAT = RF × EACAT _BASE . Thus, the catalyst warm-up retard amount EACAT changes as shown by the solid line (normal time) in FIG. 14 after the start of the engine start operation.

On the other hand, if it is determined in step 1501 that the ignition timing rotational speed control is currently being executed (if IN = 1), the flow advances to step 1505 to decrease the current catalyst warm-up retard amount by a fixed value ΔEA. And at step 150
7 and 1509 restrict the minimum value of EACAT to 0. As a result, the value of EACAT becomes a constant value ΔEA every time this operation is performed from the time when the ignition timing speed control is started.
(Fig. 14, dotted line) and normal (Fig. 14, solid line)
Decays faster and becomes 0 in a short time.

Therefore, it is possible to prevent interference between the ignition timing adjustment by the ignition timing speed control and the catalyst warm-up delay.
It is possible to converge the engine speed to the target speed in a short time. In the present embodiment, the reduction of the catalyst warm-up delay amount is started together with the start of the ignition timing rotation speed control.
For example, since the deterioration of combustion is relatively small, the ignition timing may not be advanced too much even if the ignition timing rotation speed control is started. In such a case, if the catalyst warm-up delay amount is attenuated early, the catalyst warm-up will be delayed, so that the exhaust properties may be deteriorated as a whole. For this reason, for example, instead of starting the reduction of the catalyst warm-up retard amount simultaneously with the start of the ignition timing rotation speed control, when the ignition timing is advanced to a certain degree or more by the ignition timing rotation speed control, that is, the deterioration of combustion becomes worse. The reduction of the catalyst warm-up delay amount may be started when it is determined that the degree is somewhat large.

In this case, step 1501 in FIG.
When the value of the ignition timing rotational speed control execution flag IN becomes 1, instead of performing the decreasing operation of step 1505 and subsequent steps, in step 1501 the feedback correction amount in the ignition timing rotational speed control (β in the example of FIG. 12) ₁ x DNE +
β ₂ × IDNE + β ₃ × DDNE) is determined to be greater than or equal to a predetermined value, that is, whether or not the ignition timing is being advanced by a predetermined value or more by the ignition timing rotation speed control. When the value becomes equal to or more than the predetermined value, the decreasing operation of step 1507 and lower may be performed. (9) Ninth Embodiment In the ninth embodiment, the operation of reducing the catalyst warm-up retard amount at the time of performing the ignition timing rotation speed control is performed as in the eighth embodiment. However, in the eighth embodiment, the operation is uniformly performed. Catalyst warm-up retard amount EACA
This embodiment is different from the first embodiment in that EACAT is reduced in accordance with the degree of deterioration of combustion.

As described above, when the degree of combustion deterioration is large, the ignition timing advance amount in the ignition timing rotation speed control becomes large. For this reason, if the catalyst warm-up retardation amount becomes a large value when the degree of combustion deterioration is large, there is a possibility that accurate rotation speed control by ignition timing rotation speed control cannot be performed. Therefore, in this embodiment, the above-described reference peak rotation speed NEP ₀ of the peak rotation speed NEP at the time of starting the engine is used.
(DNP = NE ₀ −NEP) as a parameter of the degree of combustion deterioration, and when the combustion deterioration is large (DN
When P is large), the decrease in the catalyst warm-up delay amount is large,
When the combustion deterioration is small (when DNP is small), the catalyst warm-up retard amount is adjusted so that the decrease in the catalyst warm-up retard amount is small.

FIG. 16 is a flowchart for explaining the operation of controlling the catalyst warm-up retard amount in this embodiment. This operation is E
This is performed as a routine executed by the CU 10 at regular intervals. When the operation is started in FIG. 16, in step 1601, first, the catalyst warm-up retard amount EACAT
Is calculated as EACAT = RF × EACAT _BASE . Then, in step 1603, it is determined based on the value of the ignition timing rotation speed control execution flag IN whether or not the ignition timing rotation speed control is currently being executed. When the ignition timing speed control is not currently executed (when IN ≠ 1)
Then, this operation ends immediately. In this case, the catalyst warm-up retard amount becomes the normal value set in step 1601. On the other hand, when the ignition timing rotation speed control is currently being executed (I
In the case of N = 1), then in step 1605, based on the difference DNP between the reference peak rotational speed NEP ₀ to predetermined of the detected startup peak rotational speed NEP at the time of engine startup, the catalyst warm-up retard A quantity reduction factor K ₄ (K ₄ ≦ 1) is determined. Then, in step 1607, step 16
The value obtained by multiplying the coefficient K ₄ to the value of EACAT when calculated usually at 01 to end the operation is set as a catalyst warm-up delay amount EACAT.

[0129] Figure 17 is a graph showing the setting of a coefficient K _4. As shown in FIG. 17, the value of K ₄ is set to K ₄ = 1 is the value of the peak rotational speed difference DNP is negative region, DNP
Is set to a smaller value as the value of DNP increases (that is, as the degree of combustion deterioration increases) in a positive region.
As a result, in step 1607 in FIG. 16, the catalyst warm-up retard amount is set to a smaller value as the degree of combustion deterioration increases, so that the ignition timing speed control and the ignition timing retard for the catalyst warm-up interfere with each other. Is prevented.

In this embodiment, as shown in FIG. 17, the value of the coefficient K ₄ is continuously changed in accordance with the value of the peak rotation speed difference DNP. it is also possible to simplify the on to the control to set the value of K ₄ in two stages depending on whether or not. In the example of it are set the coefficient K ₄ in accordance with the peak rotational speed difference DNP in the present embodiment, the feedback correction amount after starting the ignition timing engine speed operating (Fig. _{12, β 1 × DNE + β} 2 × I
(DNE + β ₃ × DDNE) represents the advance amount by the ignition timing rotation speed operation. Therefore, depending on the value of the feedback correction amount, it is also possible to set the value of K ₄ using the same relationship as Figure 17.

[0131]

According to the inventions described in the claims, there is a common effect that the engine speed can be smoothly and smoothly converged to the target speed in the engine speed control at the time of starting the engine. .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an embodiment when the present invention is applied to an internal combustion engine for a vehicle.

FIG. 2 is a diagram illustrating a change over time of a rotation speed at the time of engine start.

FIG. 3 is a flowchart illustrating an example of a rotation speed control start operation when the engine is started.

FIG. 4 is a flowchart illustrating a peak rotation speed detection operation at the time of engine start.

FIG. 5 is a flowchart illustrating a rotation speed control start operation when the engine is started.

FIG. 6 is a flowchart illustrating an example of a target rotation speed setting operation in the rotation speed control.

FIG. 7 is a flowchart illustrating another example of a rotation speed control start operation when the engine is started.

FIG. 8 is a flowchart illustrating another example of a rotation speed control start operation when the engine is started.

FIG. 9 is a flowchart illustrating a switching operation between intake air speed control and ignition timing speed control.

FIG. 10 is a flowchart illustrating an example of an intake air amount rotation speed control operation.

FIG. 11 is a diagram illustrating setting of parameters in the operation of FIG. 10;

FIG. 12 is a flowchart illustrating an example of an ignition timing rotation speed control operation.

FIG. 13 is a diagram illustrating setting of parameters in the operation of FIG. 13;

FIG. 14 is a diagram showing a time change of a catalyst warm-up retard amount.

FIG. 15 is a flowchart illustrating an example of a catalyst warm-up retard amount control operation.

FIG. 16 is a flowchart illustrating another embodiment of a catalyst warm-up retard amount control operation.

FIG. 17 is a diagram showing parameter settings in the operation of FIG. 16;

FIG. 18 is a diagram showing an example of setting parameters in the operation of FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine main body 5, 6 ... Crank angle sensor 10 ... Electronic control unit (ECU) 16 ... Electronic control throttle valve 110 ... Ignition circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 43/00 301 F02D 43/00 301B 301K 45/00 322 45/00 322F F02P 5/15 F02P 5/15 B (72) Inventor Akihiro Katayama 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hidemi Onaka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G022 CA01 CA03 DA01 EA07 GA05 GA08 3G065 EA01 EA03 FA11 FA13 GA10 GA41 KA33 3G084 BA05 BA17 CA01 CA03 DA04 EA11 EB16 EC03 FA07 FA10 FA19 FA33 FA34 3G091 AA02 AA17 AB03 BA04 CB05 DC02 DC03 EA01 NA03 NA03 NA01 NA03 NA03 FA03 FA03 NA08 ND02 ND12 ND25 NE08 NE11 NE12 NE19 PA01A PA01Z PA11Z PE01A PE02Z PE09A

Claims (14)

[Claims] 1. A control device for an internal combustion engine for performing a speed control for feedback-controlling an engine speed to a predetermined target speed at the time of engine start, wherein an engine intake air amount from the start of the engine start operation is integrated. A control of the internal combustion engine, comprising: an accumulating means; and starting the rotation speed control when the integrated value of the intake air amount calculated by the accumulating means reaches a value equal to the intake passage volume from the throttle valve to each cylinder inlet. apparatus. 2. A control device for an internal combustion engine for performing a speed control for feedback-controlling an engine speed to a predetermined target speed at the time of engine start, wherein the engine speed is set to a peak speed at the time of start after the engine start operation is started. A control device for an internal combustion engine, comprising: means for detecting that the engine speed has reached the number, and starting the engine speed control when the arrival at the peak engine speed is detected. And a target rotation speed setting means for gradually changing the target rotation speed from the peak rotation speed to a predetermined reference rotation speed with the passage of time from the start of the rotation speed control. The control device for an internal combustion engine according to claim 2. 4. When the deviation of the actual engine speed from the reference speed becomes smaller than a predetermined value after the start of the speed control, the target speed setting means sets the deviation in advance. 4. The control device for an internal combustion engine according to claim 3, wherein the target rotational speed is changed such that a time rate of change of the target rotational speed becomes smaller than a case where the target rotational speed is larger than a predetermined value. 5. 5. A control device for an internal combustion engine for performing a speed control for feedback-controlling an engine speed to a predetermined target speed when the engine is started, comprising: means for calculating a change speed of the engine speed. A control device for an internal combustion engine, which starts the rotational speed control when the calculated engine rotational speed change speed becomes equal to or less than a predetermined value after the start operation is started. 6. A control device for an internal combustion engine that performs a speed control to feedback-control an engine speed to a predetermined target speed at the time of engine start, wherein the engine speed is equal to the target speed after an engine start operation is started. A control device for an internal combustion engine, which starts the rotation speed control when they become equal. 7. When the engine is started, the engine speed is controlled to a predetermined target speed by an intake air speed control for feedback-controlling the engine intake air amount according to the engine speed, and the engine combustion at the time of engine start is performed. Judgment of the deterioration is performed, and when the combustion is deteriorated, the intake amount rotation speed control is switched to the ignition timing rotation speed control for controlling the engine rotation speed to the target rotation speed by feedback-controlling the engine ignition timing according to the engine rotation speed. A control device for an internal combustion engine that controls the rotation speed at the time of engine start to a target rotation speed, wherein the ignition timing is advanced by a predetermined advance amount compared to before the start at the time of starting the ignition timing rotation speed control. A control device for an internal combustion engine, wherein the control of the ignition timing speed is started from the start. 8. The engine according to claim 1, further comprising means for detecting a peak rotation speed at the start after the start of the engine start operation, wherein the advance amount is determined according to a difference between a predetermined reference peak rotation speed and the peak rotation speed at the start. The control device for an internal combustion engine according to claim 7, further comprising a setting unit. 9. A learning means for learning the reference peak rotational speed based on a starting peak rotational speed in a case where ignition timing rotational speed control has not been performed at the time of starting the engine up to the previous time. A control device for an internal combustion engine according to claim 8. 10. When starting the engine, the engine speed is controlled to a predetermined target speed by intake air speed control for feedback-controlling the engine intake air amount in accordance with the engine speed, and the engine combustion during engine start is controlled. Judge whether there is any deterioration,
When the combustion deteriorates, the intake air speed control is switched from the intake air speed control to the ignition timing speed control for controlling the engine speed to a target speed by feedback-controlling the engine ignition timing according to the engine speed, and the engine speed at engine start is switched. A control device for an internal combustion engine that controls the target rotation speed and the actual rotation speed of the engine by controlling a feedback control constant in at least one of the intake air rotation speed control and the ignition timing rotation speed control. The control device for an internal combustion engine, further comprising: setting means for setting based on a difference between the difference and a time change rate of the difference. 11. A rotation speed control for setting a feedback control constant by at least the setting means, among the intake air speed control and the ignition timing rotation speed control, is a deviation of an actual rotation speed from the target rotation speed. 11. The control device for an internal combustion engine according to claim 10, wherein the control is a proportional-integral-differential control based on a proportional amount proportional to, an integral amount that is a time integral value of the deviation, and a differential amount that is a time differential value of the deviation. . 12. When the engine is started, the engine speed is controlled to a predetermined target speed by intake air speed control for feedback-controlling the engine intake air amount according to the engine speed, and the engine combustion at the time of engine start is performed. Judge whether there is any deterioration,
When the combustion deteriorates, the intake air speed control is switched from the intake air speed control to the ignition timing speed control for controlling the engine speed to a target speed by feedback-controlling the engine ignition timing according to the engine speed, and the engine speed at engine start is switched. The internal combustion engine controller further controls the ignition timing at a predetermined catalyst warm-up time after the catalyst temperature rise in order to promote the temperature rise of the exhaust purification catalyst disposed in the engine exhaust passage at the time of engine start. A catalyst warm-up means for delaying the catalyst warm-up delay amount and changing the catalyst warm-up retard amount so that the catalyst warm-up retard amount becomes zero after a predetermined time has elapsed from the start of the engine start operation; The engine means changes the catalyst warm-up retard amount such that the catalyst warm-up retard amount becomes zero in a shorter time when the ignition timing speed control is performed than when the ignition timing speed control is not performed. Let , Internal combustion engine control device. 13. When the engine is started, the engine speed is controlled to a predetermined target speed by intake air speed control for feedback-controlling the engine intake air amount according to the engine speed, and the engine combustion at the time of engine start is performed. Judge whether there is any deterioration,
When the combustion deteriorates, the intake air speed control is switched from the intake air speed control to the ignition timing speed control for controlling the engine speed to a target speed by feedback-controlling the engine ignition timing according to the engine speed, and the engine speed at engine start is switched. The internal combustion engine controller further controls the ignition timing at a predetermined catalyst warm-up time after the catalyst temperature rise in order to promote the temperature rise of the exhaust purification catalyst disposed in the engine exhaust passage at the time of engine start. A catalyst warm-up means for delaying the ignition timing by the retard amount; and a means for detecting a start-time peak rotational speed after the start of the engine start operation. An internal combustion engine that sets the catalyst warm-up retard amount to be smaller by an amount corresponding to a difference between a predetermined reference peak rotation speed and the start-time peak rotation speed as compared with a case where rotation speed control is not performed; Control device. 14. When the engine is started, the engine speed is controlled to a predetermined target speed by intake air speed control for performing feedback control of the engine intake air amount according to the engine speed, and the engine combustion at the time of engine start is started. Judge whether there is any deterioration,
When the combustion deteriorates, the intake air speed control is switched from the intake air speed control to the ignition timing speed control for controlling the engine speed to a target speed by feedback-controlling the engine ignition timing according to the engine speed, and the engine speed at engine start is switched. The internal combustion engine controller further controls the ignition timing at a predetermined catalyst warm-up time after the catalyst temperature rise in order to promote the temperature rise of the exhaust purification catalyst disposed in the engine exhaust passage at the time of engine start. Catalyst warm-up means for retarding the catalyst by a retard amount, wherein the catalyst warm-up means performs the catalyst warm-up delay when the ignition timing rotation speed control is performed, compared to when the ignition timing rotation speed control is not performed. A control device for an internal combustion engine, wherein an angle amount is set to be small according to a feedback correction amount of ignition timing in ignition timing rotation speed control.