JPH06317207A - Idle speed control device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] The present invention relates to an idle speed control device that feedback-controls an intake air amount during idling to ensure a desired idle speed, and always provides appropriate responsiveness and control accuracy regardless of ignition timing. The purpose is to secure and. [Structure] The ignition timing set in the internal combustion engine is read (step 100). Engine speed N in a given engine
The average value NeSM of e is calculated, and the change amount ΔNe of NeSM is calculated.
Is calculated (steps 102 to 106). ｜ ΔNe ｜ ＞
When Ne changes so much that Ne is satisfied (step 108), the correction air amount IQA is calculated as a larger value as the retard amount is larger according to the detected ignition timing, and the intake air amount is controlled. K, which is the valve opening amount
IQA is added to QA to perform feedback control as a new KQA (steps 110 and 112).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device, and more particularly to an idle speed control device for an internal combustion engine which realizes a desired idle speed by feedback-controlling an intake air amount during idling.

[0002]

2. Description of the Related Art In order to reduce the fuel consumption of an internal combustion engine, it is desirable that the engine speed (hereinafter referred to as idle speed) during idling where running torque is not required be as low as possible. On the other hand, when the internal combustion engine is operating in the extremely low speed region, the internal combustion engine is apt to stall, and it is necessary to control the rotational speed with high accuracy in order to reduce the set rotational speed.

In order to meet such requirements, in recent years, idle speed control (ISC control) for controlling the intake air amount with high accuracy at the time of idling has been widely performed. This ISC control is applied to the intake pipe of the internal combustion engine.
A passage for bypassing the throttle valve is provided, and an idle speed control valve (ISCV) for controlling conduction of the passage is provided for highly accurate feedback control of the intake air amount during idling.

In other words, when the load on the internal combustion engine during idling increases due to the start of the air conditioner (A / C) or the like, the ISCV is opened wider to increase the intake air amount, and the load decreases. In some cases, IS
The opening of CV is reduced to reduce the intake air amount.

In this case, the IS is monitored while monitoring the engine speed.
If the CV is feedback-controlled, the internal combustion engine is supplied with the air amount necessary to maintain the desired idle speed with respect to the load that is actually acting on the internal combustion engine. As a result, the desired idling speed can be accurately maintained.

Incidentally, in controlling the internal combustion engine, it is sometimes convenient to control the ignition timing. Combustion in the combustion chamber of an internal combustion engine is greatly affected by the compression state of the air-fuel mixture during ignition, and the combustion pressure and exhaust gas temperature generated can be controlled appropriately by appropriately adjusting the timing. Because.

That is, when ignition is performed near the top dead center where the air-fuel mixture is most compressed, the ignited air-fuel mixture explosively burns to generate a high combustion pressure and the combustion is promptly performed. The temperature of the exhaust gas becomes relatively low because it ends. On the other hand, when the ignition timing is retarded, the combustion speed of the air-fuel mixture becomes slower, so the output characteristics deteriorate as the combustion pressure decreases, while the gas that is still burning is exhausted. The exhaust temperature becomes high.

Therefore, for example, if the ignition timing retard control is executed at the cold start in an internal combustion engine having a catalytic converter in the exhaust passage, which is known as an exhaust gas purification device, the catalytic converter can be warmed up early. It will be possible.
It should be noted that the catalytic converter has the property of exhibiting a good exhaust gas purification action when the temperature is raised to a predetermined activation temperature range, and the shorter the time required to complete the warm-up after starting the internal combustion engine, the better. It is possible to obtain various exhaust emission.

From this point of view, a device using a combination of the above-mentioned ISC control and ignition timing control has been conventionally known. For example, in the Toyota Technical Disclosure Publication (published by Toyota Motor Corporation) No. 4331, both are combined. An idle speed control device having such a function is disclosed.

In other words, this device has a stable idle rotation even when the ignition timing retardation control that makes the operating state more unstable is executed during cold start of the internal combustion engine, which tends to make the operating state unstable. The number of the catalyst converters is maintained at a high level, and high temperature exhaust gas is discharged while maintaining good maneuverability, so that the catalytic converter is warmed up early.

[0011]

By the way, the influence of the change in the amount of air supplied to the internal combustion engine on the output characteristic of the internal combustion engine is greatest when the ignition timing is set near the top dead center. Is known to become smaller as it is retarded. When the ignition timing is retarded as described above, the efficiency of converting combustion energy into output torque is inferior to that when ignition is performed near the top dead center, and the output torque generated per unit air amount decreases. Because it will be.

That is, when the ignition timing is set near the top dead center in the internal combustion engine, a slight change in the intake air amount appears as a large output torque change, that is, a change in the rotational speed, while the ignition timing is retarded. When controlled, the output torque does not change so much even with a slight change in the intake air amount, and as a result, the rotation speed does not change.

As described above, the rotational speed sensitivity to changes in the intake air amount is greatly affected by the set ignition timing. However, the ISC control in the above conventional device is
This characteristic was not paid attention to, and the opening of ISCV was feedback-controlled by always increasing or decreasing a fixed correction air amount regardless of the ignition timing.

Therefore, in the case where a sudden load change occurs in the state where the ignition timing is retarded, the step width of increasing the intake air amount by the feedback control is too small, and the response of the intake air amount control is increased. In some cases, the engine could not follow the change in the load, causing an engine stall in some cases.

The present invention has been made in view of the above points, and the correction air amount, which is the range of increase or decrease of the intake air amount in the feedback control, is made variable according to the set ignition timing, and the ignition timing is delayed. It is an object of the present invention to provide an idle speed control device capable of solving the above-mentioned problems by executing feedback control with a larger increase / decrease width as the angle is increased.

[0016]

FIG. 1 is a block diagram showing the principle of the present invention. As shown in the figure, in order to achieve the above object, in the present invention, when the internal combustion engine 1 is in an idling state, the operating state of the internal combustion engine with respect to the supplied basic air amount is detected and Intake air amount feedback control means for performing a feedback control of the intake air amount by calculating the new basic air amount by increasing or decreasing the correction air amount when calculating the basic air amount so that the state becomes a predetermined state. In the idle speed control device 3 including 2, the correction air amount control means 4 is provided for detecting the ignition timing of the internal combustion engine 1 and for setting the correction air amount to be larger as the detected ignition timing is retarded. An idle speed control device 3 characterized in that

[0017]

In the idle speed control device according to the present invention, the internal combustion engine 1 continues to operate by repeating explosions that occur at the ignition timing set at a predetermined timing. The intake air amount feedback control means 2 increases / decreases the correction air amount to the basic air amount to maintain a predetermined idle speed when the internal combustion engine 1 is in an idling state, and feedback control of the intake air amount is performed. To execute. At this time, the corrected air amount is set to be larger by the corrected air amount control means 4 as the ignition timing of the internal combustion engine 1 is retarded.

Therefore, when the internal combustion engine 1 is ignited in the vicinity of the top dead center, that is, when the rotational speed sensitivity to changes in the intake air amount is sensitive, the intake air amount is feedback-controlled with a small width, and When the ignition timing of the internal combustion engine 1 is retarded, that is, when the rotational speed sensitivity to changes in the intake air amount is insensitive, the intake air amount is feedback-controlled in a wide range.

[0019]

FIG. 2 is a system configuration diagram of an internal combustion engine equipped with an idle speed control device according to an embodiment of the present invention.
In this embodiment, a 4-cylinder 4-cycle spark ignition internal combustion engine 20 is used.
An example in which the present invention is applied is shown in the figure, and the figure shows a structural cross-sectional view of any one of the four cylinders. In this internal combustion engine 20, each system unit is controlled by an electronic control unit (hereinafter referred to as ECU) 21 described later.

In the figure, a piston 23 that vertically reciprocates in the figure is housed in a cylinder block 22 of an internal combustion engine 20, and a combustion chamber 24 communicates with an intake manifold 25 via an intake valve 26. , Exhaust valve 2
It is connected to the exhaust manifold 28 via 7. An ignition plug 29 is provided in the combustion chamber 24 so that the plug gap projects.

An upstream side of the intake manifold 25 is connected to an intake pipe 31 via a surge tank 30 for all four cylinders. The throttle valve 3 is provided in the intake pipe 31.
3 and an air flow meter 32 are provided respectively. The throttle valve 33 has a structure in which the opening is adjusted in conjunction with the accelerator pedal, and the opening is detected by a throttle position sensor 34 (incorporating an idle switch for detecting an idle state). It is said that. An intake air temperature sensor 35 that measures the intake air temperature is provided downstream of the air flow meter 32.

A bypass passage 36 that bypasses the throttle valve 33 and connects the upstream side and the downstream side of the throttle valve 33 is provided.
An idle speed control valve (ISCV) 37 whose valve opening degree is controlled by, for example, a stepping motor is attached in the middle of. A fuel injection valve 38 injects fuel into the air flow passing through the intake manifold 25 in accordance with an instruction from the ECU 21 described later.

Further, an oxygen concentration detection sensor (O ₂ sensor)
Reference numeral 39 is provided so as to partially penetrate the exhaust manifold 28 to detect the oxygen concentration in the exhaust gas before entering the catalyst device 40. The catalyst device 40 is a member for purifying unburned components (CO, HC, etc.) and oxides (NOx, etc.) in the exhaust gas, and a catalyst bed temperature sensor so as to protrude partially through the outer wall to detect the internal temperature. 43 is provided.

A water temperature sensor 42 is provided so as to penetrate the cylinder block 22 of the internal combustion engine 20 and partially project into the water jacket, and detects the water temperature of the internal combustion engine cooling water. An igniter 43 generates a high-voltage ignition signal in accordance with an ignition timing signal transmitted from the ECU 21 at a predetermined timing.

Reference numeral 44 designates a distributor, which is a cylinder discrimination sensor 45 for generating a reference position detection signal of the internal combustion engine crankshaft, and an internal combustion engine rotational speed signal, for example, 30.
The ignition signal supplied from the igniter 43 is appropriately distributed to the ignition plugs 29 of the respective cylinders according to the rotation angle of the crankshaft.

The ECU 21 is composed of hardware as shown in FIG. 3, and is a main part of the apparatus of the present embodiment which realizes the intake air amount feedback control means 2 and the correction air amount control means 4 described above. Hereinafter, referring to FIG. 3, the ECU 2
1 and various sensors and ECU 2 necessary for realizing the above-described idle speed control device 3
A detailed description will be given of transmission and reception of a signal to and from 1. Incidentally, in FIG. 3, the same components as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 3, an ECU 21 includes a central processing unit (CPU) 50, a read only memory (ROM) 51 storing a processing program, a random access memory (RAM) 52 used as a work area, an internal combustion engine. A backup RAM 53 that retains data even after the stop,
Input interface circuit 54, A / with multiplexer
It is composed of a D converter 55, an input / output interface circuit 56, and the like, which are connected to each other via a common bus 57.

The A / D converter 56 receives an intake air amount detection signal from the air flow meter 32, a detection signal from the throttle position sensor 34, an intake air temperature detection signal from the intake air temperature sensor 35, and an oxygen concentration detection signal from the O ₂ sensor 39. The catalyst bed temperature detection signal from the catalyst bed temperature sensor 41 and the water temperature detection signal from the water temperature sensor 42 are sequentially switched and fetched through the input interface circuit 54, converted into an analog / digital signal, and sequentially sent to the bus 57.

The input / output interface circuit 56 inputs a rotation speed signal from the rotation angle sensor 46 according to the internal combustion engine speed (NE) to the CPU 50 via the bus 57.

Further, the CPU 50 is the above-mentioned A / D converter 5
5 and the various data input from the input / output interface circuit 56 through the bus 57, various arithmetic processes are executed, and the obtained data is passed through the bus 57 and the input / output interface circuit 56 to the ISCV 37, the fuel injection valve 38,
It is appropriately selected and output to the igniter 43 to control the opening of the ISCV 37 to control the idle speed to the target speed,
The fuel injection time by the fuel injection valve 38, that is, the control injection amount per unit time is controlled, and the ignition timing is controlled by the igniter 43.

In this case, the control of the fuel injection time by the fuel injection valve 38 is calculated by a widely known fuel injection time calculation process. That is, the absolute amount of the intake air amount is calculated based on the detection signals of the air flow meter 32 and the intake air temperature sensor 35, and the injection time for realizing the stoichiometric air-fuel ratio for the air amount is calculated as the basic injection time.

The throttle position sensor 34
The water temperature sensor 42 allows the driver's request and the internal combustion engine 20
Of the combustion gas, and the actual air-fuel ratio of the combustion gas is detected by the O ₂ sensor 39 to satisfy the required acceleration characteristics, ensuring stable operation during warm-up.
In addition, the basic injection time is corrected in order to realize highly accurate air-fuel ratio control.

The ignition timing control by the igniter 43 is executed by a conventionally known method based on the detection signal of the catalyst bed temperature sensor 41 and the detection signal of the rotation angle sensor 46. That is, when the generation timing of the ignition timing signal is set on the basis of the pulse signal supplied from the rotation angle sensor 46, the ignition timing is retarded and set if the catalyst device 40 is at a low temperature, and the catalyst device 40 is set to the desired timing. If the temperature has risen to the temperature, it is set as a regular timing.

By the way, when the idle speed control is executed in the device for executing the ignition timing control as described above, as shown in FIG.
It should be noted that the zero speed sensitivity varies depending on the ignition timing. As shown in the figure, when the ignition timing is greatly retarded, the sensitivity is greatly reduced. Therefore, the engine speed Ne can be increased or decreased with a slight change in the intake air amount. Because you can't.

That is, when the ignition timing is advanced, a slight change in the air amount greatly affects Ne, so the intake air amount must be finely adjusted, and the ignition timing is retarded. In this case, the rotation speed cannot be controlled unless the intake air amount is changed to some extent.

Therefore, in the apparatus of this embodiment, the ISC
When executing the control to perform the idle speed control, the correction air amount, which is the increase / decrease range of the air amount in the feedback control, is made variable depending on the set ignition timing. The amount of air is controlled by feedback, and the feedback control of the amount of air is performed with a large width during retard control.

An example of ISC control executed by the apparatus of this embodiment will be described in detail below with reference to the flow chart shown in FIG.

The ISC control routine is a routine that is started when the throttle position sensor 34 detects that the throttle valve 33 is fully closed, that is, when the internal combustion engine 20 is in the idling state. I for realizing a desired idle speed
It is a routine for setting the opening degree of the SCV 37.

As shown in the figure, when this routine is started, the ignition timing is read in step 100. This routine is a process for executing the feedback control of the intake air amount with the corrected air amount according to the ignition timing. In the device of this embodiment, the ignition timing is set in the ECU 20 as described above, and here,
The calculation result will be read.

By the way, the idle speed control by the ISC control is a feedback control of the ISCV so that the engine speed Ne is maintained at a predetermined idle speed. Therefore, if Ne is detected and compared with a predetermined determination value, and the opening degree of the ISCV 37 is set again large or small according to the comparison result, the control is basically established.

However, as long as Ne fluctuates within a small range, there will be no problem in the operating characteristics of the internal combustion engine 20. In addition, N controlled near a predetermined idle speed
If the opening degree of the ISCV 37 is adjusted every time e crosses the level of the judgment value, the ISCV 37 operates extremely frequently, which is extremely disadvantageous in terms of durability and the like.

Therefore, in the present embodiment, the opening adjustment of the ISCV 37 is not executed unless Ne changes significantly to some extent. As a means for this, the change in the average value of Ne over a predetermined engine is compared to determine the rotation speed. We adopted a configuration that determines the presence or absence of fluctuations.

That is, in step 102, the engine speed Ne is calculated based on the output signal of the rotation angle sensor 46, then the process proceeds to step 104, and the average value NeSM of Ne in the past predetermined period is calculated. Then, in the following step 106, the change amount ΔNe between the previously calculated NeSM and the present NeSM is calculated.

According to this structure, ΔNe does not change significantly even if Ne is slightly changed, and ΔNe does not change.
By determining whether or not exceeds a predetermined determination value, it is possible to accurately detect a situation in which the opening of the ISCV 37 really needs to be adjusted.

Therefore, in step 108, | ΔNe
| Is compared with a predetermined judgment value ΔNe1, and | ΔNe |> Δ
If Ne1 is satisfied, it is assumed that the engine speed Ne has changed significantly this time, and the processing from step 110 is executed to reset the opening degree of the ISCV 37, and | ΔNe |> ΔNe1
If it is determined that is not established, the current process is terminated without performing any process.

By the way, in the present routine, the above step 1
If it is determined in step 08 that | ΔNe |> ΔNe1 holds, in step 110, IQA corresponding to the above-described corrected air amount is calculated. And step 11
2 to KQA which is the opening instruction amount of ISCV37,
The IQA is added to calculate a new KQA, and the processing of this time is ended.

That is, when | ΔNe |> ΔNe1 is satisfied, that is, when Ne largely fluctuates, the opening instruction amount KQA set at that time is | ΔNe | and ΔN.
The width of the corrected air amount IQA is reset so as to reduce the difference from e1. If | ΔNe |> ΔNe1 is still satisfied when the present routine is started next time, a new KQA is further set within the IQA range.

As described above, in this routine, the ISC is performed by the above steps 102 to 108 and 112.
Feedback control of the opening degree of V37 is executed, and the intake air amount feedback control means 2 described above is realized by these steps.

Further, in this routine, the above step 1
Reference numeral 10 is a main part of the apparatus of this embodiment, which is a step for realizing the above-described corrected air amount control means 4. That is, step 110 is a step of calculating IQA according to the ignition timing read in step 100, and is characterized by the processing content. The contents of the process executed in step 110 will be described below with reference to FIG.

FIG. 6 is a map stored in ROM 51 for use in step 110. The control amount IQAB shown on the vertical axis of this map is the corrected air amount I
It has a meaning as a correction coefficient of QA. That is, as shown in FIG. 4, the rotational speed sensitivity to changes in the intake air amount becomes less sensitive as the ignition timing is retarded.

In other words, in order to ensure good rotational speed sensitivity when the ignition timing is retarded, it is necessary to greatly change the intake air amount. Therefore, in this routine, the control amount IQAB is preset as shown in FIG. 6, and IQA is calculated by the following equation.
Is calculated.

IQA = IQAB × (−Ne / | ΔNe |) × (1-Kq × (−Ne / | ΔNe |)) (1) where (−Ne / | The term ΔNe |) indicates whether the change in the rotational speed Ne is an increase or a decrease,
This is a term for expressing as a positive / negative sign. Therefore, if the phenomenon when it is determined that | ΔNe |> ΔNe1 is satisfied in step 108 is due to the rise of Ne, the sign of IQA is negative, and the phenomenon is due to the fall of Ne. If so, the sign of IQA becomes positive.

As a result, in step 112, when Ne rises, the value of KQA is small, that is, the ISCV opening is set small in order to reduce the intake air amount, and when Ne falls, KQA is reduced. The value is large, that is, the ISCV opening is set large to increase the intake air amount.

The width in which KQA is changed in these cases, that is, the absolute value of IQA, is the control amount I shown in FIG.
Depending on the QAB, the larger the ignition timing is retarded, the larger the value will be.

In the above equation (1), Kq is a correction coefficient for obtaining an appropriate correction air amount depending on whether the engine speed Ne increases or decreases. That is, when the idle speed control is executed, the control responsiveness becomes a problem when the load of the internal combustion engine 20 suddenly increases, that is, when Ne decreases.

While the engine stalls when the engine speed Ne decreases due to poor response, the engine stalls.
This is because when Ne increases, even if the responsiveness is poor, Ne only temporarily increases. Further, when Ne rises, if the opening degree of the ISCV 37 is transiently reduced, the engine stall may occur due to the influence.

The term relating to the correction coefficient Kq in the above equation (1) is set in consideration of such a characteristic. Due to the presence of this term, IQA is large when Ne falls, and Ne
When rising, IQA is set to be relatively small.

As described above, according to this routine, the corrected air amount IQA is large when the engine is retarded and the IQA is advanced when the engine is advanced according to the ignition timing of the internal combustion engine 20. It will be set small.

As a result, I executed in one routine
The degree of influence of the opening degree adjustment of the SCV 37 on the engine speed Ne is always kept substantially constant regardless of the ignition timing retard / advance, and the intake air amount is fed back with appropriate responsiveness. Control will continue.

By the way, in the device for controlling the ignition timing in the idling state like the device of this embodiment, in order to early warm up the catalyst device 40, the ignition timing is greatly retarded and the required output torque is secured. To ISCV
When the load of the internal combustion engine 20 is further increased in a state where 37 is wide open, there is a case where the required air amount cannot be supplied even when the ISCV 37 is fully opened.

In this case, if no processing is taken, the internal combustion engine 20 will stall. Also, I
If the configuration that increases the air supply capacity of the SCV 37 is adopted, the problem of capacity is solved, but the feedback control in such an area is accompanied by the large opening and closing of the ISCV 37, and the control accuracy of the intake air amount is increased. , ISCV37 is not preferable from the viewpoint of durability.

On the other hand, as shown in FIG. 7, the sensitivity of the engine speed Ne to the variation amount of the ignition timing has a characteristic that it becomes more sensitive as the ignition timing is retarded. This is because when the ignition timing is greatly retarded, a slight variation in the retard amount greatly affects the combustibility.

Therefore, in such a situation, although it is contrary to the purpose of early warm-up of the catalyst device 40, if the ignition timing is controlled regardless of the intake air amount, the control accuracy of the intake air amount will be good. Can be maintained at the standard, I
There is no problem in durability of the SCV 37, and the internal combustion engine 20 can be maintained in a suitable state as a whole.

FIG. 8 shows the internal combustion engine 2 from such a viewpoint.
The flowchart of an example of the routine which performs the idle speed control of 0 using both intake air amount control and ignition timing control is shown. Hereinafter, a second example of the routine process executed by the ECU 21 will be described with reference to FIG.

Here, steps 100 to 112 in the routine processing shown in FIG. 8 are steps corresponding to the corresponding steps in the routine processing shown in FIG. 5 described above.

That is, when the processing shown in FIG. 8 is started,
In steps 100 to 108, the ignition timing is read, the engine speed Ne is calculated, and the average value NeSM of Ne and the amount of change ΔNe thereof in a predetermined period are calculated based on the calculation result, and | ΔNe |> Ne1 is determined. I do.

If | ΔNe |> Ne1 is not established, the opening adjustment of the ISCV 37 is deemed unnecessary, and the process is terminated. If | ΔNe |> Ne1 is established, the engine speed that has changed significantly The processing from step 120 onward is executed to control the number Ne to an appropriate value.

Step 120 is prepared in case the feedback control of the ignition timing needs to be executed in a case where the idle speed cannot be controlled to an appropriate value only by adjusting the opening degree of the ISCV 37. The following is the step of calculating the correction air amount ISA related to the ignition timing by the formula.

ISA = ISAB × (−Ne / | ΔNe |) × (1-Ks × (−Ne / | ΔNe |)) (2) Here, in the formula (2), ISAB is the above. This is a correction coefficient that is obtained by referring to the preset map as shown in FIG. 9 with the ignition timing read in step 100, with the control amount corresponding to ISAB in the equation (1). Here, as shown in FIG. 7, the sensitivity characteristic of the rotational speed with respect to the variation of the ignition timing becomes more sensitive as the retard angle is increased.
In the map shown in FIG. 9, the control amount ISAB is set to be large on the advance side and small on the retard side in order to correspond to such a characteristic.

In equation (2), (-Ne / | ΔNe |)
The term of is a term for expressing whether the change of the rotation speed Ne is an increase or a decrease as a positive / negative sign, and in the equation (2), Ks is the same as Kq in the equation (1). , A correction coefficient for obtaining an appropriate correction air amount depending on whether the engine speed Ne increases or decreases.

After the ISA is calculated in this way, in step 110, the corrected air amount IQA relating to the feedback control of the intake air amount is calculated according to the above equation (1). Then, when the calculation of these corrected air amounts ISA and IQA in consideration of the ignition timing is completed, in step 122, | ΔNe | <ΔNe2 is determined.

Here, ΔNe2 is a judgment value for formally distinguishing whether the change in Ne occurring in the internal combustion engine 20 is large or small. When | ΔNe | is small, the feedback control of the intake air amount can often be used, and when | ΔNe | is large, there is a situation in which the feedback control of the intake air amount cannot be used. The purpose is to make that determination.

Therefore, in step 122, | ΔNe
When it is determined that | <ΔNe2 is satisfied, that is, the engine speed Ne has changed only slightly, the catalyst device 4
In order to leave 0 degrees of freedom for early warm-up, etc., in principle, feedback control of the intake air amount will be used.
If it is determined that | ΔNe | <ΔNe2 is not established, the routine proceeds to step 124, where the set ignition timing S
A is on the delay side from the predetermined determination timing RSA (SA <RSA)
Is determined.

This is because the Ne control should not be performed by the intake air amount as described above when the Ne change generated in the internal combustion engine 20 is large and the ignition timing is set large on the retard side. Therefore, when it is determined in step 124 that SA <RSA is established, the routine proceeds to step 126, where the ignition timing feedback control using the previously calculated corrected air amount ISA is executed, and the processing is ended.

On the other hand, when it is determined in step 124 that the ignition timing is controlled on the advance side of RSA, in principle, the intake air amount of the intake air amount is set in the same manner as when | ΔNe | <ΔNe2 holds. The process proceeds to step 128 to deal with the feedback control. Here, step 128
Is a step of determining whether or not the current KQA corresponding to the opening of the ISCV 37 has an appropriate margin with respect to the upper limit value KQA _MAX .

That is, the currently set KQA is
Limit value KQA_MAXSmaller than the value obtained by subtracting the predetermined value a from
For example, the feedback control of the intake air amount controls the Ne.
I knew I could update the KQA further to implement
Refuse. Also, KQA <KQA _MAX-If a is not satisfied
Thus, the ISCV37 will no longer have the engine speed Ne at the desired speed.
It is judged that there is not enough room to maintain the number of turns.

If it is determined that the control of the intake air amount can be taken, the routine proceeds to step 112, where the idle speed control by the intake air amount is executed using the corrected air amount IQA calculated by the above equation (1). To set a new KQA. If it is determined that the control of the intake air amount cannot be dealt with, the process proceeds to step 126 and a new KSA is set so as to execute the idle speed control based on the ignition timing, and the present process is ended.

As described above, according to this routine, by appropriately using feedback control based on the intake air amount and feedback control based on the ignition timing, the idle speed can be appropriately adjusted without unreasonably large adjustment of the opening of the ISCV 37. Number control can be realized. Therefore, in the idle speed control device that executes this routine, the speed accuracy during idling and the ISC
It is possible to secure the durability of V37 and the early warm-up of the catalyst device 40 at a high level.

[0079]

As described above, according to the present invention, when the internal combustion engine is in the idling state, the correction air is reduced as the sensitivity of the engine speed to the variation of the intake air amount decreases with the retardation of the ignition timing. The amount is set large. Therefore, despite such a decrease in sensitivity, it is possible to ensure appropriate responsiveness in feedback control even during ignition retard control.

Further, when the ignition timing is controlled to the advance side, the correction air amount of the intake air amount is set small,
Despite the situation in which the engine speed fluctuates greatly even with a slight change in the air amount, it is possible to maintain appropriate accuracy in controlling the speed.

As described above, when the idle speed control device according to the present invention is used together with the ignition timing control, the idle speed control device is always unaffected by the ignition timing and has an appropriate response and accuracy. It has the feature that control can be executed.

[Brief description of drawings]

FIG. 1 is a principle diagram of an idle speed control device according to the present invention.

FIG. 2 is a system configuration diagram of an internal combustion engine including an idle speed control device that is an embodiment of the present invention.

FIG. 3 is a block configuration diagram showing a hardware configuration around an electronic control unit of the apparatus of this embodiment.

FIG. 4 is a graph showing the relationship between the ignition timing of the internal combustion engine and the engine speed sensitivity with respect to changes in the intake air amount.

FIG. 5 is a flowchart of an example of ISC control executed by the apparatus of this embodiment.

FIG. 6 is an example of a map referred to by the apparatus of this embodiment in the ISC control.

FIG. 7 is a graph showing the relationship between the ignition timing of the internal combustion engine and the engine speed sensitivity to variations in the ignition timing.

FIG. 8 is a flowchart of another example of ISC control executed by the device of this embodiment.

FIG. 9 is an example of a map referred to by the apparatus of this embodiment in the ISC control.

[Explanation of symbols]

1, 20 Internal combustion engine 2 Intake air amount feedback control unit 3 Idle speed control device 4 Corrected air amount control unit 21 Electronic control unit (ECU) 29 Spark plug 32 Air flow meter 33 Throttle valve 34 Throttle position sensor 35 Intake temperature sensor 37 Idle Speed control valve (ISC
V) 38 Fuel injection valve 39 O ₂ sensor 41 Catalyst bed temperature sensor 42 Water temperature sensor 43 Igniter 44 Distributor 45 Cylinder discrimination signal 46 Rotation angle sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location F02D 45/00 312 C 7536-3G 362 J 7536-3G F02P 5/15 E

Claims (1)

[Claims] 1. When the internal combustion engine is in an idling state, the operating state of the internal combustion engine with respect to the supplied basic air amount is detected, and the basic air amount is calculated so that the operating state becomes a predetermined state. In the idle speed control device that executes a feedback control of the intake air amount by calculating the new basic air amount by increasing or decreasing the correction air amount when performing the ignition timing of the internal combustion engine, the detected ignition timing And a correction air amount control means for controlling the correction air amount to increase as the angle is retarded.