JPH062596A - Idle speed control device for engine - Google Patents

Abstract

PURPOSE:To improve convergency as good as possible to a target speed of an idle speed by including a primary advance correction limiting means, which limits primary advance correction in the next time for a predetermined period so that the leading preceding time primary advance correction is not influenced to the next time primary advance correction, in a primary advance correction coefficient arithmetic processing means. CONSTITUTION:In a load flag value setting means 51, a load flag value is set to 1, 0 by on-off of a power steering switch 34, to store the load flag value, set in the means 51, in a load flag memory means 52. In an inhibition time setting means 53, time for inhibiting primary advance correction is set by the stored load flag value, and in a primary advance correction coefficient arithmetic means 54, a primary advance correction coefficient is calculated based on the correction inhibiting time set in the means 53 and the stored load flag value. Thus by constituting a primary advance correction limiting means 55 for limiting primary advance correction in the next time for a predetermined period after executing the preceding time primary advance correction, correction is prevented from being excessively applied, to obtain a proper idle speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adjusts the amount of air supplied to the engine when the throttle valve is fully closed by an idle adjusting valve to feedback control the actual engine speed during the idle operation to a target idle speed. The present invention relates to an engine idle speed control device.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a general engine system. First, the structure and operation of this general engine system will be described.

In FIG. 8, an intake system 4 of an engine 2 is provided with an air cleaner 6, an air flow sensor 8, a throttle valve 10 and an injector 12 from the upstream side thereof, and the throttle valve 10 has its opening degree. There is provided a throttle position sensor 14 for detecting the above, and an idle switch 16 for detecting its fully closed state. In addition, a bypass passage 18 that connects the upstream side and the downstream side of the throttle valve 10 is provided in the throttle valve 10, and an idle adjustment valve 20 as a solenoid valve is provided in the bypass passage 18.

As is well known, the intake air temperature sensor 22,
There are various sensors such as the engine water temperature sensor 24, the engine rotation sensor 26, and the air-fuel ratio sensor 28 that detect the operating state and load state of the engine 2, and the state information of these is input to the control unit 30.

Although not shown, the engine 2
Drive auxiliary devices such as a compressor of an air conditioner and a power steering pump are connected to the output shaft of the engine. By the operation of these drive auxiliary devices, various external loads other than the traveling drive load are appropriately applied to the engine 2. Therefore, external load information is input to the control unit 30 from the air conditioner switch 32 and the power steering switch 34 in order to detect these various external loads.

The control unit 30 performs various engine controls such as the idle speed control by the idle adjusting valve 20 based on the status information from the various sensors and switches.

Next, a conventional example, for example, Japanese Patent Laid-Open No. 3-1996
The operation of the engine idle speed control device described in Japanese Patent No. 46 will be described with reference to the flowcharts of FIGS. 9 and 10. The idle speed control operation shown in this flowchart is executed when the idle switch 16 is turned on.

When the conventional idle speed control device is activated, first, at step S10, the flag xrst, which is an index for indicating that it is the first time, is lowered to xrst = 0, and at the next step S20, the engine speed is changed. The operating state information of the engine 2 and the operating states of the driving accessories are read from various sensors such as the sensor 26 and the air flow sensor 8 and various switches such as the air conditioner switch 32 and the power steering switch 34.

Next, in step S30, a target idle speed No. is set in accordance with the engine water temperature and the operating state of the external load, and in step S40 the engine 2 is operated in a steady operation at this target idle speed No. The required basic air charging efficiency Cebase is calculated. Step S50
Then, the feedback correction value Cefb corresponding to the deviation between the detected actual idle speed Ne of the engine 2 and the target idle speed No with respect to the basic air charging efficiency Cebase.
Is added to calculate the first target air charging efficiency Cetno. The feedback correction value Cefb is shown in FIG.
12 is read from the graph of the characteristic diagram of FIG. 12 at every predetermined time (for example, 160 msec) according to the flowchart of the interrupt routine shown in FIG.

Next, at step S60, the supply air amount is kept constant at the first target air mass flow rate Gno where the first target air charging efficiency Cetno is obtained, and in this state, the engine is detected for actual idle rotation. The charging efficiency when the steady operation is continued at several Ne is the second target air charging efficiency Cetne.
It is calculated as (i) = Gno / Ne.

Next, in step S70, it is judged whether or not this time is the second time or later based on whether or not the flag xrst is 1. If xrst = 1, the process proceeds to step S80, and in this step, When the idle adjustment valve 20 is set to the opening for supplying the first target air mass flow rate Gno, the primary delayed air charging efficiency Cetned (i) that is sucked into the cylinder 2a under the actual idle speed Ne is calculated. . Cetned (i) is calculated by the following formula: Cetned (i) = KSKCCA × Cetned (i-1) + (1-KSKCCA) × Cetne (i), and this first-order lag air charging efficiency Cet
ned (i) is almost uniquely determined according to the engine specifications.

Further, the determination in step S70 is NO.
If it is the first time, the process proceeds to step S90, and the second target air charging efficiency Cetne calculated in step S60 is calculated as the previous value Cetne (i-1) of the second target air charging efficiency.
(I) is substituted as it is for convenience, and the current value Cetned (i) of the first-order lagging air charging efficiency is also set in step S60.
For convenience sake, the second target air charging efficiency Cetne (i) calculated in step 3 is directly substituted.

Next, in step S100, the first-order lagging air charging efficiency Cetned (i) is the second target air charging efficiency Cetne.
The insufficient filling efficiency dCetned = Max (Cetne−Cetned, 0) is calculated by considering only the case of shortage with respect to (i).

Next, at step S110, the insufficient air mass flow rate dGa = d corresponding to the above-mentioned insufficient filling efficiency dCetned.
Cetned × Ne / K is calculated, and the next step S120
Then, the primary advance coefficient adv for adding and correcting the insufficient air mass flow rate dGa is read based on the characteristic diagram of FIG. Then, in the next step S130, based on the first-order advance coefficient adv, the final target air-filling efficiency Cetned (i) is made equal to the second target air-filling efficiency Cetne (i). The efficiency Cecont is calculated by the following formula.

Cecont (i) = (Cetne (i) -adv × C
etne (i-1)) / (1-adv) In the next step S140, based on the final target air charging efficiency Cecont (i), the final target air mass flow rate Gtotal (i) = Cecont. (i) × Ne / K is calculated,
Further, in the next step S150, from the final target air mass flow rate Gtotal (i), the volume flow rate qisc of air actually passing through the idle adjusting valve 20 = Gtotal (i) / γ-qma.
in is required. Where qmain is the throttle valve 1
0 is the volumetric flow rate of air leaking.

Next, in step S160, a control duty ratio D based on the coil temperature correction coefficient cthw of the idle adjustment valve 20, the battery voltage correction coefficient cbat, and the volume flow rate qisc of air actually passing through the idle adjustment valve 20.
After (i) is read from the graphs of the respective characteristic diagrams of FIGS. 14, 15, and 16, respectively, in the next step S170,
The final control duty ratio D = cbat * cthw * D (i) is calculated by multiplying D (i) by cbat and cthw, and the opening degree of the idle adjusting valve 20 is controlled based on this D.

Then, in the next step S180, the current value Cetne (i) of the second target air charging efficiency Cetne is set as the previous value Cetne (i-1), and then the control flow is returned to step S20.

As described above, the final target air mass flow rate Gto
When the opening degree of the idle control valve 20 is controlled based on tal, the first-order lagging air charging efficiency actually sucked into the cylinder 2a follows the change of the second target air charging efficiency Cecont in the ideal state, and Cecont Therefore, when the actual idle speed Ne matches the target idle speed No, the primary delayed air charging efficiency that is actually sucked into the cylinder 2a can be changed. After that, the actual idle speed Ne can be brought as close as possible to the air charging efficiency required to continue to operate at the target idle speed No. Therefore, the actual idle speed Ne resulting from the insufficient air charging efficiency Phenomenon of underwater (undershoot)
Further, it is possible to prevent the occurrence of a hunting phenomenon accompanying this, and to improve the convergence of the actual idle speed Ne to the target idle speed No as much as possible.

[0019]

However, in the above idle speed control device, the idle speed is always controlled based on the deviation between the actual idle speed Ne and the target idle speed No. For example, depending on the timing of turning on and off the external load such as power steering, the first-order lead phase correction is superimposed and becomes excessive,
Therefore, there is a possibility that the actual idle speed Ne may overshoot.

This will be described with reference to FIG. Figure 7
(A) shows a power steering flag XPST indicating operation or non-operation of power steering, and flag XPST = 1 indicates power steering operation.
XPST = 0 indicates no power steering operation. First, XPST
= 1, adv is set positive at time t1 (FIG. 7 (b)), and the final target air charging efficiency Cecont is calculated based on this (FIG. 7 (c)), and the target idle speed is calculated from No1. Change to No2, the actual idle speed Ne
Increases toward the target idle speed No2. However, at the next time t2, XPST = 0 and ad
v is set to a negative value, the final target air charging efficiency Cecont is calculated based on this, and the target idle speed is now N
It changes from o2 to No1 and the actual idle speed Ne decreases toward the target idle speed No1, but continues at time t.
At 3 and t4, when the actual idle speed Ne is lower than the target idle speed No1 and adv is set to be positive,
As shown by the hatched portion in FIG. 7 (c), the final target air charging efficiency Cec is influenced by the adv at the time t1 and is superimposed on the adv.
Overshoot occurs at ont, and as shown by the hatched portion in FIG. 7D, overshoot occurs at the actual idle speed Ne that far exceeds the target idle speed No2.

As described above, in the conventional idle speed control device, there is a possibility that the actual idle speed Ne may be overshot due to the influence of the previous adv.

The present invention has been made in order to solve the above problems, and its object is to superimpose the next primary advance correction while the influence of the previous primary advance correction coefficient remains. To provide an engine idle speed control device capable of suppressing the occurrence of overshoot or undershoot and improving the convergence of an actual idle speed to a target speed as much as possible without excessive correction. is there.

[0023]

To achieve the above object, the present invention provides an idle adjusting valve for adjusting the idle speed by adjusting the flow rate of air supplied to the engine when the throttle valve is fully closed, and an actual idle speed. And a control unit for controlling the opening degree of the idle adjustment valve so as to converge the detected rotation speed to a target idle rotation speed according to operating state data such as engine water temperature. A target idle speed setting means for setting an idle speed, and a basic charging efficiency required for operating the engine at the target idle speed in a steady state are calculated, depending on a deviation between the target idle speed and an actual idle speed. In addition to the basic filling efficiency,
Target air charging efficiency calculation means for obtaining the target air charging efficiency of the above, and a value obtained by multiplying the first target air charging efficiency by the target idle speed is divided by the actual idle speed. Second target air filling efficiency calculating means for obtaining the second target air filling efficiency, and primary delay air when the idle adjustment valve is set to the first target air mass flow rate for obtaining the first target air filling efficiency. Calculate the filling efficiency,
An insufficient air mass flow rate calculating means for calculating an insufficient air charge efficiency which is a difference between the second target air charge efficiency and the first-order lag air charge efficiency, and converting the insufficient air charge efficiency into an insufficient air mass flow rate; Primary advance correction coefficient calculation processing means for calculating a primary advance correction coefficient from the insufficient air mass flow rate; and the primary advance correction coefficient using the primary advance correction coefficient so that the primary delayed air filling efficiency matches the second target air filling efficiency. The second target air filling efficiency is corrected to calculate the final target air filling efficiency, and the final target air mass flow rate calculating means for converting the final target air filling efficiency into the final target air mass flow rate and the idle adjusting valve are passed. The air volume flow rate to be made is calculated from the final target air mass flow rate, the control duty ratio of the idle adjustment valve is obtained from the air volume flow rate, and this control duty ratio is supplemented. In the idle speed control device for the engine having the final control duty ratio calculating means for controlling the opening degree of the idle adjusting valve according to the final control duty ratio, In order to prevent the influence of the correction from reaching the next-order advance correction, the first-preceding correction limiting means for limiting the first-order advance correction for a predetermined period after the execution of the first-time advance correction is included.

Further, the primary advance correction limiting means is a load flag value setting means for setting a load flag value to "1" or "0" depending on the operation or non-operation of the driving accessories, and the set load flag. Load flag value storage means for storing a value, prohibition time setting means for setting a time for prohibiting correction by the first-order advance correction coefficient by the stored load flag value, the set correction prohibition time, and the stored correction prohibition time. The primary lead correction coefficient computing means for computing the primary lead correction coefficient based on the load flag value.

Further, the drive accessories may be power steering.

[0026]

In the engine idle speed control device according to the present invention, the subsequent first-order advance correction is restricted for a predetermined period after the preceding first-order advance correction is executed. While the influence of 1 remains, the primary correction coefficient of the next time does not overlap, the excessive correction can be prevented, and the convergence of the idle speed to the target speed can be improved as much as possible.

Further, when the primary advance correction is carried out due to the external load variation due to the activation of the driving auxiliary machinery, the operation / non-operation of the driving auxiliary machinery is set and stored as a flag value, and this flag value is stored. If the prohibition time of the primary advance correction is set from the above, and the primary advance correction coefficient is calculated based on the prohibition time and the stored flag value, the drive auxiliary machine is in the operating state (first operation). State) and then becomes a non-operating state, and then again becomes an operating state (second operating state). In that second operating state, the primary advance correction is not performed in accordance with the predetermined time. Idle speed control can be performed, and the influence of the primary advance correction coefficient value in the first operating state of the drive accessories on the subsequent second operating state can be eliminated. Prevents overshoot Rukoto can.

Further, when the drive accessories are power steering, the engine rotation is greatly increased even when the steering wheel is turned to the left or right within a short time when the vehicle is moving forward and backward in the idle rotation range. There is no.

[0029]

2 is a block diagram showing an embodiment of an engine idle speed control device according to the present invention.

In FIG. 2, the target idle speed setting means A1 of the control unit 30 is the engine water temperature sensor 2
The target idle speed No. is set by inputting the operating state data consisting of the water temperature data output from No. 4 and the operating / non-operating signal output from the driving accessories 36.

The first target air charging efficiency calculating means A2, which receives the target idle speed No and the actual idle speed Ne output from the engine speed sensor 26, operates the engine in the steady operation at the target idle speed No. The basic charging efficiency required for the calculation is calculated, and a correction value corresponding to the deviation between the target idle speed No and the actual idle speed Ne is added to the basic charging efficiency to obtain the first target air charging efficiency Cet.
Calculate no.

The second target air charging efficiency calculating means A3 is
The second target air filling efficiency Cetne is calculated by dividing the value obtained by multiplying the first target air filling efficiency Cetno calculated by the means A2 by the target idle rotation speed No by the actual idle rotation speed Ne.

The insufficient air mass flow rate calculating means A4 calculates the first-order lagging air charge efficiency Cetned when the idle adjustment valve 20 is set to the first target air mass flow rate Gno which gives the first target air charge efficiency Cetno. , The second target air filling efficiency Cetne and the first-order lagging air filling efficiency Cetned are calculated, and the insufficient air filling efficiency dCetned is converted into the insufficient air mass flow rate dGa.

The first-order advance correction coefficient calculation processing means A5 inputs a signal for turning on or off the power steering switch 34, which is a signal indicating the operation or non-operation of the power steering, and makes a first-order advance from the insufficient air mass flow rate dGa under a predetermined condition. Correction coefficient ad
Calculate v.

The final target air mass flow rate calculating means A6 uses the primary advance correction coefficient adv so that the primary delayed air filling efficiency Cetned matches the second target air filling efficiency Cetne. The final target air charging efficiency Cecont is calculated by correcting the charging efficiency Cetne, and this final target air charging efficiency Cecont is converted into the final target air mass flow rate Gtotal using the actual idle speed Ne.

The final control duty ratio calculating means A7 calculates the air volume flow rate qisc to be passed through the idle adjusting valve 20 from the final target air mass flow rate Gtotal, and the control duty ratio D of the idle adjusting valve 20 from the air volume flow rate qisc. (I) is obtained, and the control duty ratio D (i) is used to determine the coil temperature of the idle adjusting valve 20 and the battery-35.
The opening degree of the idle adjusting valve 20 is controlled by the final control duty ratio D corrected by the output voltage of.

The first-order advance correction coefficient calculation processing means A5 is shown in detail in FIG. Primary advance correction coefficient calculation processing means A5
In, the load flag value setting means 51 sets the load flag values to “1” and “0” by turning on and off the drive accessories such as the power steering switch 34, and the load flag storage means 52 is set by the means 51. The stored load flag value is stored. Further, the prohibition time setting means 53 sets the time for prohibiting the primary advance correction by the stored load flag value, and the primary advance correction coefficient calculation means 54 stores the correction inhibit time set by the means 53 and the above. The first-order advance correction coefficient is calculated based on the load flag value. That is, the load flag value setting means 51, the load flag storage means 52, the prohibition time setting means 53, and the primary advance correction coefficient calculation means 54 limit the next primary advance correction for a predetermined period after the execution of the previous primary advance correction. The primary advance correction limiting means 55 is configured.

Next, the operation of the embodiment of FIG. 2 and the operation of the primary advance correction coefficient calculation processing means A5 of FIG. 1 will be described with reference to FIGS.
This will be described with reference to the flowchart of FIG. 5 and the time chart of FIG.

3 and 4 are flow charts for explaining the operation of the embodiment shown in FIG.
9 is different from FIGS. 9 and 10 only in steps S1 and S120A, and therefore these steps will be described.

In step S1, T = 0. The setting of T = 0 is the initial setting of the prohibition time T used in the flowchart of FIG. 5 showing the adv calculation process of step S120A in detail.

Next, step S120A will be described with reference to the flowchart of FIG. 5 and the time chart of FIG. 6 showing the details of the process. In the time chart of FIG. 6, the load flag X of the power steering as the driving auxiliary machinery
The PST is the same as in the case of FIG. First, it is determined whether the prohibition time T is zero (step S201). Since the initial value of the prohibition time T is set to zero in step S1, the process proceeds from step S201 to step S202. In step S202, it is determined whether the power steering switch is on. At the first determination time t1 shown in FIG. 6, the load flag XPST (i) (i = 1) = 1 (step S203), indicating that the power steering switch 34 is on and the power steering is operating.

Next, it is determined whether or not XPST (i) = 1 (step S204). Load flag XPST (i)
Is set to "1" at time t1, the process proceeds to step S205, and it is determined whether the prohibition time T = 0. Since T = 0 now, the primary advance correction coefficient adv
Is calculated and the process returns to step S120A.

Next, at time t2, the load flag XP
Since ST (i) (i = 2) is "0" (power steering is in a non-operating state) (step S207), step S20.
The process proceeds from step 4 to step S208, and the prohibition time T is set to the predetermined time K (step S209). After setting T = K, the primary advance correction coefficient adv is calculated and returns in step S206. Next, at time t3, since T ≠ 0, the prohibition time T = K−1 (step S2).
10) and XPST (i) (i = 3) = 1 again (step S203). Therefore, the process proceeds from step S204 to step S205, but since T ≠ 0, the primary advance correction coefficient adv becomes “0” (step S211).
To return. As can be seen from steps S205 and S211, adv = 0 is maintained while the power steering operation state continues and the inhibition time T> 0.

Next, at time t5 via time t4, the inhibition time T = 0, the first-order lag correction coefficient adv becomes positive, and the final target air charging efficiency Cecont begins to increase. As the final target air charging efficiency Cecont increases,
The actual idle speed Ne, which has been gradually increasing until then, rapidly increases and reaches the target idle speed No2 without overshoot.

As described above, the power steering shifts from the first operating state at the time t1 to the non-operating state at the time t2, and further the time t passes.
When the second operation state of No. 3 is entered, a prohibition time T of a predetermined time K is provided from the time of the non-operation state, and in the second operation state, there is no first-order delay correction for a time corresponding to the predetermined time K. Idle speed control is performed. This allows
It is possible to eliminate the influence of the first-order advance correction coefficient adv in the first operating state of the drive accessories on the subsequent second operating state, and prevent overshoot of the actual idle speed Ne. That is, specifically, when the vehicle is parked in the garage, even if the steering wheel is turned back and forth in a short time while moving forward and backward in the idle rotation range, the engine rotation does not greatly rise, and operability is improved. improves.

Although the power steering has been described in the above embodiment, the present invention can be similarly applied to other driving accessories such as a compressor for an air conditioner and has the same effect. Further, the present invention can also be applied to a large number of drive accessories, and in this case, the flowchart shown in FIG. 5 may be created for each drive accessory and these flow charts may be connected in series in time. In this series connection,
When the prohibition time is set in any of a large number of drive accessories, idle speed control without primary delay correction is performed.

[0047]

As described above in detail in the embodiments, in the engine idle speed control device according to the present invention, after the preceding preceding first-order advance correction is executed,
Since the next primary advance correction that follows is limited for a predetermined period, it is possible to prevent the next primary correction coefficient from overlapping while the influence of the previous primary correction coefficient remains, and prevent excessive correction. Thus, the convergence of the idle speed to the target speed can be improved as much as possible.

Further, when the primary advance correction is performed due to the external load fluctuation due to the activation of the driving auxiliary machinery, the operation / non-operation of the driving auxiliary machinery is set and stored as a flag value, and this flag value is stored. If the prohibition time of the primary advance correction is set from the above, and the primary advance correction coefficient is calculated based on the prohibition time and the stored flag value, the drive auxiliary machine is in the operating state (first operation). State) and then becomes a non-operating state, and then again becomes an operating state (second operating state). In that second operating state, the primary advance correction is not performed in accordance with the predetermined time. Idle speed control can be performed, and the influence of the primary advance correction coefficient value in the first operating state of the drive accessories on the subsequent second operating state can be eliminated. Prevents overshoot Rukoto can.

Further, when the power accessories are used as the drive accessories, the engine rotation is large even when the steering wheel is turned back and forth in a short time while moving forward and backward in the idle rotation range when the vehicle is parked. It does not blow up and improves operability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first-order lag correction coefficient calculation processing means constituting an embodiment of an engine idle speed control device according to the present invention.

FIG. 2 is a block diagram showing an embodiment of an engine idle speed control device according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the embodiment of FIG.

FIG. 4 is a flow chart for explaining the operation of the embodiment of FIG.

5 is a flow chart for explaining the operation of the primary delay correction coefficient calculation processing means in FIG. 1. FIG.

6 is a time chart for explaining the operation of the first-order lag correction coefficient calculation processing means in FIG.

FIG. 7 is a time chart for explaining the operation of the conventional idle speed control device.

FIG. 8 is a configuration diagram showing a general engine system.

FIG. 9 is a flowchart for explaining the operation of the conventional idle speed control device.

FIG. 10 is a flowchart for explaining the operation of a conventional idle speed control device.

FIG. 11 is a flowchart of feedback correction value calculation.

FIG. 12 is a graph showing a feedback correction value with respect to a deviation.

FIG. 13 is a graph showing a first-order advance correction coefficient with respect to an insufficient air mass flow rate.

FIG. 14 is a graph showing a correction coefficient of a coil temperature of an idle adjusting valve.

FIG. 15 is a graph showing a correction coefficient with respect to battery-voltage.

FIG. 16 is a graph showing a control duty ratio with respect to an air volume flow rate.

[Explanation of symbols]

 A4 Insufficient air mass flow rate calculation means A5 Primary advance correction coefficient calculation processing means A6 Final target air mass flow rate calculation means 34 Power steering switch 51 Load flag value setting means 52 Load flag value storage means 53 Prohibited time setting means 54 Primary advance correction coefficient calculation means

Claims (3)

[Claims] 1. An idle adjustment valve for adjusting an idle speed by adjusting a flow rate of air supplied to an engine when a throttle valve is fully closed, and an actual idle speed detected to detect the detected speed as an operating condition such as engine water temperature. A control unit for controlling the opening of the idle adjusting valve so as to converge the target idle speed according to the data; the control unit includes a target idle speed setting means for setting the target idle speed, and an engine To calculate a basic charging efficiency required for normal operation of the engine at the target idle speed, and add a correction value corresponding to a deviation between the target idle speed and the actual idle speed to the first target efficiency. First target air charging efficiency calculation means for obtaining air charging efficiency; and multiplying the first target air charging efficiency by the target idle speed. Second target air charging efficiency calculating means for obtaining a second target air charging efficiency by dividing the obtained value by the actual idle speed, and a first target air mass for obtaining the first target air charging efficiency. The primary lagging air filling efficiency is calculated when the idle adjustment valve is set to the flow rate, and the insufficient air filling efficiency that is the difference between the second target air filling efficiency and the primary lagging air filling efficiency is calculated. Insufficient air mass flow rate calculation means for converting the air filling efficiency into insufficient air mass flow rate, primary advance correction coefficient calculation processing means for calculating a primary advance correction coefficient from the insufficient air mass flow rate, and the primary delayed air charge efficiency is the first The second target air charging efficiency is corrected by using the first-order advance correction coefficient so as to match the target air charging efficiency of 2, and the final target air charging efficiency is calculated. A final target air mass flow rate calculation means for converting the rate to a final target air mass flow rate, and an air volume flow rate to be passed through the idle adjustment valve is calculated from the final target air mass flow rate, and the air volume flow rate of the idle adjustment valve is calculated. A control duty ratio is obtained, and a final control duty ratio calculation means for controlling the opening of the idle adjusting valve by the final control duty ratio obtained by correcting the control duty ratio, and an idle speed control device for an engine, comprising: The correction coefficient calculation processing means limits the primary advance correction for a predetermined period after execution of the previous primary advance correction so that the influence of the preceding primary advance correction does not reach the next primary advance correction. An engine idle speed control device comprising means. 2. The load flag value setting means for setting the load flag value to “1” or “0” depending on the operation or non-operation of the driving accessories, and the set load flag. Load flag value storage means for storing a value, prohibition time setting means for setting a time for prohibiting correction by the first-order advance correction coefficient by the stored load flag value, the set prohibition time and the stored An engine idling speed control device for an engine according to claim 1, further comprising: primary advance correction coefficient calculation means for calculating a primary advance correction coefficient based on a load flag value. 3. The engine idle speed control device according to claim 2, wherein the drive accessory is a power steering.