JPH11182301A - Idling speed control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an idling speed control valve for an internal combustion engine which can speedily converge the engine speed to a target value irrespective of abrupt or slow application of external load. SOLUTION: A steering 51 is operated at the time of idling an engine 1, and a power steering 52 is driven. An air amount is corrected, and supplied to the engine 1 through an idling speed control valve 41. The air is gradually corrected with a preset value serving as an upper limit guard value, so that the engine speed is kept as a target value. The upper limit guard value is set large when a variation rate of the engine speed sensed at the first time after starting the power steering 52 is large. The upper limit guard value is set small when the variation rate of the engine speed is small.

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 for controlling an idle speed of an internal combustion engine, and more particularly to a device for controlling an idle speed when an external load is operated.

[0002]

2. Description of the Related Art Generally, when an external load such as a power steering is operated during idle speed control of an engine of an automobile or the like, the amount of air bypassing a throttle valve is corrected by controlling the drive of an idle speed control valve. Controlled.

FIG. 17 shows a control mode of the idle speed by the air amount correction when the external load operates.
This will be described based on the time chart shown in FIG. Note that FIG.
FIG. 17A shows the transition of the power steering operation determination flag XPS which is turned “ON” when the power steering operates, FIG. 17B shows the transition of the engine speed NE, and FIG.
FIG. 7C shows the transition of the power steering correction amount QPS as the correction air amount at the time of power steering operation.

As shown in FIG. 17, when the power steering is operated at time t1 and the power steering operation determination flag XPS is switched from "off" to "on", the load increase due to the operation of the power steering is offset. Thus, air amount correction for maintaining the engine speed NE at the target speed NTRG starts. At this time, the power steering correction amount QPS is immediately increased by a predetermined amount a. After time t1, the power steering correction amount QPS is gradually increased by a predetermined increase / decrease amount ΔQ in response to a decrease in rotation of the engine speed NE over time. By gradually increasing the power steering correction amount QPS, time t2
, The correction amount QPS is equal to a predetermined upper guard value QPSG.
Upon reaching D, the gradual increase of the correction amount QPS is stopped. The upper guard value QPSGD is a value set to supply a large amount of required air at a required timing.

[0005] From time t2 to time t3, the rotation speed of the engine speed NE decreases with time. However, the above power steering correction amount QP
Since S has reached the upper limit guard value QPSGD, the power steering correction amount QPS is equal to the guard value QPSG.
D is maintained.

[0006] After time t3, the power steering correction amount QPS is gradually reduced by the predetermined increase / decrease amount ΔQ in response to recovery from a drop in the engine speed NE.
Due to the gradual decrease of the power steering correction amount QPS, the correction amount QPS becomes a predetermined lower limit guard value QP at time t4.
When Sgd is reached, the gradual decrease of the correction amount QPS is stopped. The lower guard value QPSgd is a value set to maintain the power steering correction amount QPS at the time of power steering operation to a predetermined amount (QPSgd) or more and to prevent engine stall.

[0007] From time t4 to time t5, the engine speed NE recovers from a drop in rotation with the lapse of time. However, since the power steering correction amount QPS has reached the lower limit guard value QPSgd, the power steering correction amount QPS is maintained at the same guard value QPSgd.

Further, after the time t5, the power steering correction amount QP is increased by the predetermined increase / decrease amount ΔQ in response to the rotation decrease of the engine speed NE with time.
S is incremented. This power steering correction amount QPS
With the gradual increase of the engine speed NE, the rotation drop of the engine speed NE stops, and at time t6, the engine speed NE converges to the target engine speed NTRG in a state where the load increase due to the operation of the power steering is canceled.

[0009] Such a change in the power steering correction amount QPS (air amount correction) in response to a drop in the engine rotation speed NE due to the power steering operation cancels the load increase due to the power steering operation, and the engine rotation speed NE. Is maintained at the target rotation speed NTRG.

[0010]

In the above control, an upper limit guard value QPSGD for supplying a large amount of air required at a timing required for the power steering correction amount QPS is set. However, in the setting of the upper limit value for the power steering correction amount QPS, for example, when the power steering operates gently and the rotation drop of the engine speed NE decreases, for example, the engine speed NE is reduced. Target rotation speed N
It has been confirmed by the inventors that the convergence to TRG becomes unstable. The control mode of the idle speed when the power steering operates gently and the rotation drop is small will be described with reference to a time chart shown in FIG. In FIG. 18, FIG. 18A shows the transition of the power steering operation determination flag XPS,
FIG. 18B shows the transition of the engine speed NE, and FIG.
(C) shows the transition of the power steering correction amount QPS.

As shown in FIG. 18, when the power steering operation determination flag XPS is switched from "off" to "on" at time t1 ', first, at time t1', the power steering correction amount QPS is equal to the predetermined amount a. It is increased at a stretch.

After the time t1 ', the correction amount QPS is gradually increased by the predetermined increase / decrease amount ΔQ in response to a decrease in the engine speed NE with time. As described above, since the rotation drop of the engine speed NE is small here, the power steering correction amount QPS does not reach the upper limit guard value QPSGD, and the engine speed NE shifts from a decrease to an increase. Time t2 '
The above gradual increase is repeated until. Therefore, the power steering correction amount QPS is excessively corrected for a small rotation drop of the engine speed NE.

From time t2 'to time t3', the power steering correction amount QPS is gradually reduced by the predetermined increase / decrease .DELTA.Q in accordance with the recovery of the engine speed NE from falling down with the lapse of time. . However, as described above, the power steering correction amount QP at time t2 '
Since S is excessively corrected, the recovery from the drop in the engine rotational speed NE after the time t2 'is excessively corrected to reach the time t3'.

When the engine speed NE drops again after time t3 ', the power steering correction amount QPS is gradually increased by the increase / decrease amount ΔQ.
Then, at time t4 ', the power steering correction amount Q
PS is again overcorrected. As a result, the recovery from the rotation drop after the time t4 'is also corrected excessively again to reach the time t5'.

As described above, when the rotation drop of the engine speed NE is small, so-called control hunting is performed for the rotation drop of the engine speed NE and the recovery from the rotation drop by excessive correction of the power steering correction amount QPS. And the convergence of the engine speed NE to the target engine speed NTRG becomes unstable.

Conventionally, for example, Japanese Patent Application Laid-Open No. 4-365941
Engine speed NE
There is a device that corrects the upper limit guard value QPSGD according to the above, but it cannot cope with the above-mentioned steepness of the load operation.

The present invention has been made in view of the above circumstances, and an object thereof is to quickly converge an engine speed to a required target speed regardless of the speed of operation of an external load such as a power steering. An object of the present invention is to provide an idle speed control device for an internal combustion engine that can be operated.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above object, the invention according to claim 1 corrects the amount of air supplied to the internal combustion engine in response to the operation of an external load when the engine is idling to correct the engine speed. In the idle speed control device for the internal combustion engine, which controls the target rotation speed to a required target rotation speed, wherein a guard value for calculating and setting each upper limit guard value corresponding to the operation amount of the external load with respect to the correction amount of the supplied air amount. The point is to provide a value setting means.

According to this configuration, the upper limit guard value is set according to the operation amount of the external load. Therefore, it is possible to appropriately correct the amount of air for promptly converging the engine speed to the required target speed without depending on the speed of the operation of the external load.

According to a second aspect of the present invention, in the idle speed control device for an internal combustion engine according to the first aspect, the guard value setting means changes the amount of operation of the external load at a predetermined timing. The gist is obtained based on the amount, and the gist is that a larger upper limit guard value is calculated and set as the fluctuation amount of the engine speed is larger.

According to this configuration, when the fluctuation amount of the engine speed at the predetermined timing is large, that is, when the external load is suddenly operated, the engine is supplied to the engine up to the upper limit guard value which is set to a relatively large value. The amount of air generated can be corrected. Therefore, it is possible to quickly converge to the required target rotational speed.

When the variation of the engine speed at the predetermined timing is small, that is, when the external load operates slowly, the amount of air supplied to the engine is regulated to an upper limit guard value which is calculated and set smaller. Is done.
Therefore, it is possible to avoid excessively correcting the air amount and to quickly converge to the target rotation speed.

According to a third aspect of the present invention, in the idle speed control apparatus for an internal combustion engine according to the second aspect, the guard value setting means previously holds two kinds of upper limit guard values having different magnitudes, and The gist of the invention is to select and set these two types of upper limit guard values in accordance with the fluctuation amount of the engine speed at the timing of (1).

According to this configuration, the calculation load of the upper limit guard value as the guard value setting means can be greatly reduced. According to a fourth aspect of the present invention, in the idle speed control device for an internal combustion engine according to the third aspect, a larger one of the two upper limit guard values is required at a required timing. The gist is that the upper limit guard value on the smaller side is set as a value capable of preventing overcorrection of the air amount.

According to this configuration, the upper limit guard value on the larger side is set as a value capable of supplying a required amount of air at a required timing. Therefore, even when the external load suddenly operates, a large amount of required air can be supplied, and a fuel corresponding to the large amount of air can be supplied. Thereby, it is possible to generate a sufficient torque capable of coping with the external load, while preventing the engine from being stalled due to the external load,
It is possible to quickly converge to the required target rotational speed.

Further, the upper limit guard value on the smaller side is set as a value capable of preventing overcorrection of the air amount. Therefore,
Even when the external load operates gently, it is possible to avoid excessive correction of the air amount and quickly converge to the target rotation speed.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment of an internal combustion engine idle speed control apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a system configuration diagram of a gasoline engine 1 as an internal combustion engine. The engine 1 includes a cylinder block 1a, and a plurality of (only one is shown in FIG. 1) cylinders 2 are provided in the cylinder block 1a. A piston 3 provided to be reciprocable in each cylinder 2 is connected to a crankshaft 10 which is an output shaft of the engine via a connecting rod 3a, and the connecting rod 3a causes the piston 3 to reciprocate to rotate the crankshaft 10. Is to be converted.

A cylinder head 1b is mounted on the upper end of the cylinder block 1a. In each cylinder 2, a combustion chamber 4 is formed between the upper end of the piston 3 and the cylinder head 1b. An ignition plug 11 provided for each combustion chamber 4 ignites the mixture introduced into the combustion chamber 4. Similarly, the intake port 5a and the exhaust port 6a provided corresponding to each combustion chamber 4 constitute a part of the intake passage 5 and the exhaust passage 6, respectively. An intake valve 7 and an exhaust valve 8 provided corresponding to each combustion chamber 4 have respective ports 5a,
6a are respectively opened and closed. The valves 7 and 8 are opened and closed by rotation of cams (not shown) provided on the intake-side camshafts 31 and the exhaust-side camshafts 32 with the rotation of the camshafts 31 and 32, respectively. Timing pulleys 33, 34 provided at the tips of the camshafts 31, 32, respectively, are connected to the crankshaft 10 via a timing belt 35 (crankshaft 1).
The connection mode with 0 is not shown).

That is, when the engine 1 is operating, the rotational force of the crankshaft 10 is transmitted to each camshaft 3 via the timing belt 35 and the timing pulleys 33 and 34.
1, 32. As the camshafts 31 and 32 rotate, the valves 7 and 8 operate. Each of the valves 7, 8 is opened and closed at a predetermined timing in synchronization with the rotation of the crankshaft 10, that is, in response to the reciprocation of each piston 3.

A water temperature sensor 15 for detecting the water temperature (cooling water temperature) THW of the cooling water of the engine 1 is attached to the cylinder block 1a. A surge tank 16 for suppressing intake air pulsation is provided in a part of the intake passage 5, and a diaphragm-type intake pressure sensor 17 for detecting the intake pressure PM is attached to the surge tank 16. On the upstream side of the surge tank 16, a throttle valve 1 that is opened and closed based on an operation of an accelerator pedal 21 is provided.
A throttle valve 18 is provided, and the amount of air taken into the intake passage 5 is adjusted by opening and closing the throttle valve 18. A throttle sensor 19 for detecting the throttle opening TA and an idle switch 20 that is turned on when the throttle valve 18 is fully closed are attached near the throttle valve 18.

An air cleaner 23 is provided upstream of the throttle valve 18 and has an air cleaner 2.
In the vicinity of 3, an intake air temperature sensor 24 for detecting the intake air temperature THA is attached.

Further, a crank angle sensor 27 is provided near the crankshaft 10, and the sensor 27 detects the rotation speed N of the engine 1 (crankshaft 10).
E and the rotation angle (crank angle) of the crankshaft 10 in the specific cylinder are detected.

A high voltage output from the igniter 13 is applied to the ignition plug 11. The ignition timing of the ignition plug 11 is determined by the high voltage output timing from the igniter 13. The engine 1 uses an ignition plug 11 to convert an air-fuel mixture composed of intake air from an intake passage 5 and fuel injected from an injector 9 into a combustion chamber 4.
After exploding in the inside to obtain the driving force, the exhaust gas is discharged to the exhaust passage 6 through the exhaust valve 8.

The intake passage 5 has a throttle valve 1
A bypass passage 42 is provided to bypass the valve 8 and communicate between the upstream side and the downstream side of the valve 18. A rotary solenoid type idle speed control valve (hereinafter, referred to as “ISCV”) 41 is provided in the middle of the bypass passage 42. The ISCV 41 is a well-known valve configured by a driving unit (not illustrated) including a solenoid coil and a permanent magnet, and a flow control unit (not illustrated) including a rotary rotary valve. The ISCV 41 is a proportional solenoid valve that displaces the valve in the rotation direction according to the magnitude of the current flowing through the solenoid coil, and adjusts the passage area of the air.

Also, a steering wheel 5 for steering the automobile
1 is provided with a power steering 52 for assisting the operating force of the steering 51 by hydraulic pressure. The power steering 52 is provided with a power steering oil pressure switch 53 that is turned on when the hydraulic pressure in the power steering 52 is equal to or higher than a predetermined value.

Next, the configuration of an electronic control unit (hereinafter, referred to as "ECU") 61 for integrally controlling such an engine system will be described with reference to the block diagram of FIG. FIG.
As shown in FIG. 1, the ECU 61 is formed of a digital computer, and a RAM (random access memory) 63, a ROM (read only memory) 64, and a C
It has a PU (Central Processing Unit) 65, an input port 66 and an output port 67.

The CPU 65 comprises an arithmetic processing circuit.
Various arithmetic processes are executed in accordance with a control program and initial data stored in the M64 in advance. RAM 63 is CP
The calculation result by U65 is temporarily stored.

The water temperature sensor 15, the intake pressure sensor 17,
Detection signals from the throttle sensor 19, the idle switch 20, the intake air temperature sensor 24, the crank angle sensor 27, the power steering oil pressure switch 53, etc.
6 is input. These sensors 15, 17, 19, 2
Operating states of the engine 1 are detected by 0, 24, 27, and 53.

On the other hand, the output port 67 is connected to each injector 9 and each igniter 13 via a corresponding drive circuit or the like.
And ISCV41 and the like. And ECU
Numeral 61 denotes each sensor 15, 17, 19, 20, 24, 2
The injector 9, the igniter 13, the ISCV 41, and the like are suitably controlled in accordance with the control program and the initial data stored in the ROM 64 based on the detection signals from the detectors 7 and 53.

Next, idle speed control (hereinafter referred to as "ISC control") executed by the ECU 61 is described.
Will be described with reference to FIGS.
FIG. 3 is a flowchart showing a processing routine for ISC control.
It is executed at an angle interruption every predetermined crank angle (180 ° CA in the present embodiment) on condition that 0 is on.

When the process proceeds to this routine, first in step 101, the ECU 61 determines whether the engine speed N
E, cooling water temperature THW, rotation fluctuation amount DLNE, power steering operation determination flag XPS, and upper limit guard value QPS
Read GD. Here, the rotation fluctuation amount DLNE is calculated by a deviation between the engine speed NE and the engine speed detected at a crank angle of 180 ° CA before. When the rotation fluctuation amount DLNE takes a positive value, the rotation speed decreases, and when the rotation fluctuation amount DLNE takes a negative value, the rotation speed increases. Further, the power steering operation determination flag XPS is provided by the power steering hydraulic switch 5.
3 is turned on when the power steering 52 is operating, that is, when the power steering 52 is operating. The upper limit guard value QPSGD is a value calculated by an upper limit guard value calculation routine described later. The ECU 61 that has read the values NE, THW, DLNE, XPS, and QPSGD moves to step 102.

In step 102, the ECU 61 calculates the basic control air amount Qi based on the one-dimensional map shown in FIG.
The result is stored in M63 and the process proceeds to step 103.

In step 103, the ECU 61 calculates a target rotation speed NTRG based on a predetermined one-dimensional map relating to the cooling water temperature THW. This target rotation speed NTR
G is a rotation speed set to a lower value as the cooling water temperature THW increases. And the target rotation speed NT
The ECU 61 having calculated the RG calculates the target rotation speed NTRG as R
The result is stored in the AM 63 and the process proceeds to step 104.

In step 104, the ECU 61 calculates the feedback correction amount QII. The feedback correction amount QII is a feedback value for correcting the air amount so that the engine speed NE becomes the calculated target speed NTRG, and is stored in the ROM 64 relating to the deviation between the engine speed NE and the target speed NTRG. It is determined by a stored predetermined map. The feedback correction amount QII is a value calculated when the cooling water temperature THW is 80 ° C. or higher. After calculating the feedback correction amount QII, the ECU 61 calculates the feedback correction amount QI.
I is stored in the RAM 63 and the process proceeds to step 105.

In step 105, the ECU 61 calculates the power steering correction amount QPS based on a routine (power steering correction amount calculation routine) described later. The same correction amount QPS is used for the operation of the power steering 52.
This is a correction amount of the air amount with respect to the load fluctuation due to the stop. As will be described later, in calculating the same correction amount QPS, an upper limit guard based on the upper limit guard value QPSGD read in step 101 is applied. The ECU 61 that has calculated the power steering correction amount QPS,
Move to step 106.

In step 106, the ECU 61 calculates a corrected air amount Q by adding the calculated basic control air amount Qi, feedback correction amount QII and power steering correction amount QPS. The ECU 61 that has calculated the corrected air amount Q stores the corrected air amount Q in the RAM 63 and proceeds to step 107.

In step 107, the ECU 61 sets the ISCV 41 corresponding to the calculated correction air amount Q
Is calculated, and the routine proceeds to step 108. In step 108, the ECU 61 sets the calculated ISCV
The opening is output, and the subsequent processing is temporarily terminated. This ISC
By the output of the V opening, the valve of the ISCV 41 is displaced in the rotation direction. As a result, the ISCV opening is controlled, and a required air amount (corrected air amount) Q is supplied.

Next, the power steering correction amount QP
A “power steering correction amount calculation routine” for calculating and determining S will be described with reference to FIGS. 5 and 6. When the process proceeds to this routine, first, step 1
At 11, the ECU 61 determines whether or not the power steering operation determination flag XPS is "ON". Here, the power steering operation determination flag XPS is set to “ON”.
If the ECU 61 determines that
Move to

In step 112, the ECU 61 determines whether or not the rotation fluctuation amount DLNE is "0" or more.
If it is determined that the rotation fluctuation amount DLNE is equal to or greater than “0”, the ECU 6 determines that the engine speed NE is decreasing while the power steering 52 is operating.
1 proceeds to step 113.

In step 113, the ECU 61 adds a predetermined increase / decrease amount ΔQ to the previous expected correction amount QPS (i-1) for the load increase due to the operation of the power steering 52, and adds the current expected correction amount QPS (i). Is calculated. Then, the ECU 61 calculates the calculated expected correction amount QPS.
(I) is stored in the RAM 63 and the process proceeds to step 114.

In step 114, the ECU 61 stores the calculated current estimated correction amount QPS (i) in the ROM
64 plus a predetermined amount a stored in advance (QPS
It is determined whether (i) + a) is equal to or larger than the upper limit guard value QPSGD read in step 101. Note that the predetermined amount a is a power steering correction amount QPS, that is, a correction amount for increasing the correction air amount Q at once when the operation of the power steering 52 is confirmed. Due to the increase by the predetermined amount a, the load increase when the power steering 52 is operated is reduced, and the drop of the engine speed NE is reduced. Here, the amount (QPS (i) + a) obtained by adding the predetermined amount a to the current estimated correction amount QPS (i) is the upper limit guard value QPSG.
If it is determined that it is smaller than D, the ECU 61 proceeds to step 116, sets the power steering correction amount QPS to the above amount (QPS (i) + a), and ends the subsequent processing once.

In step 114, the above-mentioned quantity (Q
When it is determined that PS (i) + a) is equal to or larger than the upper limit guard value QPSGD, the ECU 61 determines in step 115
Then, the power steering correction amount QPS is set to the upper limit guard value QPSGD, and the subsequent processing is temporarily ended.

When the engine speed NE decreases during the operation of the power steering 52 by the processing of steps 113 to 116, the power steering correction amount QPS is gradually increased within a range having the upper limit guard value QPSGD as the upper limit. Is made.

On the other hand, if it is determined in step 112 that the rotation fluctuation amount DLNE is less than "0", it is determined that the engine speed NE is increasing during operation of the power steering 52, and the ECU 61 proceeds to step 121. I do.

In step 121, the ECU 61 calculates the predetermined increase / decrease amount Δ from the previous expected correction amount QPS (i−1) for the load increase accompanying the operation of the power steering 52.
By subtracting Q, the current estimated correction amount QPS (i) is calculated. The ECU 61 then calculates the calculated expected correction amount Q
PS (i) is stored in the RAM 63, and the process proceeds to step 122.

In step 122, the ECU 61 calculates the amount (QPS (i) + a) obtained by adding the predetermined amount a to the calculated current estimated correction amount QPS (i), and stores the amount in the ROM.
It is determined whether or not the size is equal to or smaller than the lower limit guard value QPSgd stored in advance in the memory 64. The lower limit guard value QPSgd is obtained by subtracting the power steering correction amount QPS when the power steering 52 is operated from a predetermined amount (QPSgd).
This is a value set for maintaining the above and preventing the occurrence of engine stall. Here, the expected correction amount Q
An amount obtained by adding the predetermined amount a to PS (i) (QPS (i) +
If it is determined that a) is larger than the lower limit guard value QPSgd, the ECU 61 proceeds to step 124 and sets the power steering correction amount QPS to the value (QPS (i)
+ A) and the subsequent processing ends once.

In step 122, the quantity (Q
If it is determined that PS (i) + a) is equal to or smaller than the lower limit guard value QPSgd, the ECU 61 proceeds to step 123.
Then, the power steering correction amount QPS is set to the lower limit guard value QPSgd, and the subsequent processing is temporarily ended.

When the engine speed NE is increasing during the operation of the power steering 52 by the processing of steps 121 to 124, the power steering correction amount QPS is gradually reduced within a range where the lower limit guard value QPSgd is the lower limit. Is made.

On the other hand, if it is determined in step 111 that the power steering operation determination flag XPS is "OFF", the ECU 61 proceeds to step 131 in FIG.

In step 131, the ECU 61 subtracts the predetermined increase / decrease amount ΔQ from the previous expected correction amount QPS (i-1) to obtain the current estimated correction amount QPS (i).
Is calculated. Then, the ECU 61 stores the calculated estimated correction amount QPS (i) in the RAM 63, and
Move to 32.

In step 132, the ECU 61 determines that the calculated current estimated correction amount QPS (i) is "0".
It is determined whether the size is as follows. Here, if it is determined that the current estimated correction amount QPS (i) is larger than “0”, the ECU 61 proceeds to step 134, where the power steering correction amount QPS is set to the estimated correction amount QPS.
(I) is set and the subsequent processing is temporarily ended.

If it is determined in step 132 that the expected correction amount QPS (i) is equal to or smaller than "0", the ECU 61 proceeds to step 133 and sets the power steering correction amount QPS to "0". Thereafter, the processing is temporarily terminated.

By the processing of steps 131 to 134, the stop of the power steering 52 causes
The power steering correction amount Q in a range where “0” is the lower limit
A gradual decrease in PS is made.

Next, the "upper guard value calculation routine" for calculating and determining the upper guard value QPSGD will be described with reference to FIG. This process is executed by a power steering control interrupt every time the power steering hydraulic switch 53 is switched from “off” to “on”. That is, the upper limit guard value QPSGD calculated in the same routine is maintained at the same value until the next time the power steering oil pressure switch 53 is turned on.

When the process proceeds to this routine, first, at step 151, the ECU 61 determines the rotation fluctuation amount D
Read LNE. The rotation fluctuation DLNE read at this time is the rotation fluctuation calculated first after the timing when the power steering oil pressure switch 53 is turned on. The ECU 61 that has read the rotation fluctuation amount DLNE proceeds to step 152.

In step 152, the ECU 61 determines whether or not the rotation fluctuation amount DLNE is, for example, 10 rpm or more. If it is determined that the rotation fluctuation amount DLNE is smaller than 10 rpm, the power steering 52
ECU 61 determines that the operation has been performed gently, and the ECU 61 proceeds to step 153. Then, in step 153, the upper limit guard value QPSGD is set to the smaller value, for example, 0.6 liters per second, and the subsequent processing is temporarily terminated. By the way, the smaller upper guard value (QPSG
D = 0.6 liters per second) is a value set to prevent overcorrection of the air amount.

If it is determined in step 152 that the rotation fluctuation amount DLNE is equal to or greater than 10 rpm, it is determined that the power steering 52 has been rapidly operated, and
61 shifts to step 154. And step 15
In 3, the upper limit guard value QPSGD is set to a larger value, for example, 1.2 liters per second, and the subsequent processing is temporarily terminated. Incidentally, the larger upper limit guard value (QPSGD = 1.2 liters per second) is a value set to supply a large amount of required air at a required timing.

The upper limit guard value QP calculated here
It is as described above that the SGD is read in step 101 (FIG. 3) and subjected to the ISC control. Next, an ISC control mode at the time of operating the power steering 52 according to the present embodiment, which is executed through each of the routines, will be described with reference to FIGS. FIGS. 8 and 9 show the case where the steering 51 is rapidly steered and the power steering 52 is rapidly operated, the rotation drop (the amount of rotation fluctuation DLNE) is large, and the steering 51 is slowly steered. The power steering 52 operates slowly, and the rotation drops (the rotation fluctuation amount DL).
6 is a time chart showing an ISC control mode when NE is small. In each of FIGS. 8 and 9, FIG.
Shows the transition of the power steering operation determination flag XPS, each figure (b) shows the transition of the engine speed NE, and each figure (c) shows the transition of the power steering correction amount QPS.

First, a case where the power steering 52 operates suddenly will be described with reference to FIG. In this case, when the power steering 52 is operated at time t11 and the power steering operation determination flag XPS is switched from “off” to “on”, an increase in load due to the operation of the power steering 52 is canceled out and the engine speed is reduced. Air amount correction for maintaining NE at the target rotation speed NTRG starts. At this time, the power steering correction amount Q
PS is immediately increased by the predetermined amount a. As described above, the increase in the power steering correction amount QPS by the predetermined amount a reduces the load increase when the power steering 52 is operated and reduces the drop in the engine speed NE as described above. It is.

After time t11, the power steering correction amount QPS is gradually increased by the predetermined increase / decrease amount ΔQ in response to the rotation drop of the engine speed NE over time (the rotation fluctuation amount DLNE is a positive value). Is done. Since the power steering 52 operates suddenly, the larger guard value (QPSG) is used for the same correction amount QPS.
D = 1.2 liters per second). By gradually increasing the power steering correction amount QPS, the time t12
When the correction amount QPS reaches the larger guard value, the gradual increase of the correction amount QPS is stopped.

After time t12, until time t13, the rotation speed of the engine speed NE corresponding to a lapse of time is continuously reduced. However, since the power steering correction amount QPS has reached the guard value QPSGD, the power steering correction amount QPS is the same as the guard value QPSG.
D is maintained.

After time t13, the power steering correction amount QPS is gradually reduced by the predetermined increase / decrease amount ΔQ in accordance with the recovery from the rotation drop of the engine speed NE (the rotation fluctuation amount DLNE is a negative value). . When the correction amount QPS reaches the lower limit guard value QPSgd at time t14 due to the gradual decrease of the power steering correction amount QPS,
The gradual decrease of the correction amount QPS is stopped.

From time t14 to time t15, recovery from a drop in the engine speed NE with a lapse of time continues. However, since the power steering correction amount QPS has reached the lower limit guard value QPSgd, the power steering correction amount QPS is maintained at the same guard value QPSgd.

Further, after the time t15, the rotation of the engine speed NE drops again with the lapse of time (the rotation fluctuation amount DL).
NE is a positive value), the power steering correction amount QPS is gradually increased by the predetermined increase / decrease amount ΔQ. With the gradual increase of the power steering correction amount QPS, the rotation drop of the engine speed NE stops, and at time t16, the engine speed NE becomes the target speed N while canceling the load increase due to the operation of the power steering 52.
Converge to TRG.

When the power steering 52 operates suddenly and the engine speed NE drops greatly, the power steering correction amount QPS is increased to the full guard value (QPSGD = 1.2 liters per second). Can be corrected. Therefore, by supplying sufficient air and supplying sufficient fuel corresponding to the air, sufficient torque capable of coping with the operation of the power steering 52 can be obtained. As described above, in the case where the rotation drop of the engine speed NE is large, a quick response is made while preventing the occurrence of engine stall.

Next, a case where the power steering 52 operates slowly will be described with reference to FIG. In this case, at time t21, the power steering 52
Is activated and the power steering operation determination flag XPS is switched from “off” to “on”, the air that maintains the engine speed NE at the target speed NTRG by canceling the load increase due to the operation of the power steering 52. The start of the amount correction is similar to the case where the power steering 52 suddenly operates. At this time, the power steering correction amount QPS is immediately increased by the predetermined amount a.

After time t21, the power steering correction amount QPS gradually increases by the predetermined increase / decrease amount ΔQ in response to the rotation drop of the engine speed NE (the rotation fluctuation amount DLNE is a positive value) over time. Is done. Since the power steering 52 operates slowly,
For the same correction amount QPS, the smaller guard value (QPS
GD = 0.6 liters per second). By gradually increasing the power steering correction amount QPS, time t2
When the correction amount QPS reaches the smaller guard value in 2, the gradual increase of the correction amount QPS is stopped.

After time t22, until time t23, it corresponds to a decrease in the engine speed NE with the lapse of time. However, since the power steering correction amount QPS has reached the guard value QPSGD, the power steering correction amount QPS is the same as the guard value QPSG.
D is maintained.

After time t23, the power steering correction amount QPS is gradually reduced by the predetermined increase / decrease amount ΔQ in accordance with the recovery from the rotation drop of the engine speed NE (the rotation fluctuation amount DLNE is a negative value). . When the correction amount QPS reaches the lower limit guard value QPSgd at time t24 due to the gradual decrease of the power steering correction amount QPS,
The gradual decrease of the correction amount QPS is stopped.

After time t24, until time t25, the recovery from the drop in the engine speed NE with the lapse of time continues. However, since the power steering correction amount QPS has reached the lower limit guard value QPSgd, the power steering correction amount QPS is maintained at the same guard value QPSgd.

Further, after the time t25, the rotation of the engine speed NE drops again with time (the rotation fluctuation amount DL).
NE is a positive value), the power steering correction amount QPS is gradually increased by the predetermined increase / decrease amount ΔQ. With the gradual increase of the power steering correction amount QPS, the rotation drop of the engine speed NE stops, and at time t26, the engine speed NE becomes the target speed N while canceling the load increase due to the operation of the power steering 52.
Converge to TRG.

As described above, when the power steering 52 operates slowly and the rotation drop of the engine speed NE is small, the upper limit of the power steering correction amount QPS is set to the smaller guard value (QPSGD = 0.6 liter per second). Is regulated. Therefore, excessive correction of the power steering correction amount QPS is avoided, and the engine speed NE quickly converges to the target speed NTRG.

As described in detail above, according to this embodiment, the following effects can be obtained. -If the engine speed NE is greatly reduced, the target engine speed NT is quickly reduced while preventing engine stall.
It can be converged to RG.

When the rotation drop of the engine speed NE is small, it is possible to avoid excessively correcting the power steering correction amount QPS, that is, the correction air amount Q,
It is possible to quickly converge to the target rotation speed NTRG.

The present embodiment is not limited to the above, but may be modified as follows. The upper limit guard value employed in the present embodiment, and the rotation fluctuation amount used for setting the upper limit guard value (DLNE = 10
rpm) and the timing for calculating the rotation fluctuation amount (18).
Numerical values such as 0 ° CA) are arbitrary. For example, the upper limit guard value may be a value that supplies a large amount of air required at a required timing and a value that prevents overcorrection of the air amount. In addition, the rotation fluctuation amount and the timing for calculating the rotation fluctuation amount may be any values as long as the operation of the power steering 52 can be determined to be slow or fast.

In this embodiment, the predetermined amount a and the increase / decrease amount ΔQ are constants. On the other hand, these predetermined amounts a
At least one of the increase and decrease ΔQ may be a variable according to the operating state of the engine 1. For example, when the rotational fluctuation amount DLNE is large (when the rotational speed drop of the engine rotational speed NE is large), by setting the predetermined amount a or the increase / decrease amount ΔQ large, it is possible to quickly respond to the rotational speed drop.

In the present embodiment, the power steering hydraulic switch 53 provided on the power steering 52 is used to detect the steering of the steering 51. On the other hand, a steering switch that is turned “ON” when the steering wheel 51 is steered may be used.

In the present embodiment, when the oil pressure in the power steering 52 is equal to or higher than a predetermined value, it is turned on.
The operation of the power steering 52 was detected by the power steering hydraulic switch 53. On the other hand, a pressure sensor may be provided in the power steering 52, and the operation of the power steering 52 may be detected based on the detection result of the pressure sensor. (Second Embodiment) Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 10 is a system configuration diagram of the gasoline engine 1 in the present embodiment. Here, the same parts as those of the present embodiment and the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, an air conditioner 37 and an air conditioner switch 38 for switching the operation and stop of the air conditioner 37 are provided in place of the power steering 52 and the power steering oil pressure switch 53 in the first embodiment. Different from form. The on / off operation of the air conditioner switch 38 connects / disconnects a compressor (not shown) of the air conditioner 37 and the crankshaft 40, thereby switching the operation / stop of the air conditioner 37. Also, this air conditioner switch 38
Detects the ON / OFF information of the air conditioner 37 together. The detection signal is input to an input port 66 (FIG. 2) of the ECU 61, and the other sensors 15, 17, 1
The detection of the operating state of the engine 1 together with 9, 20, 24, and 27 is the same as in the first embodiment.

Next, a processing operation related to the ISC control executed by the ECU 61 in the present embodiment will be described with reference to FIG.
This will be described with reference to FIGS. FIGS. 11 to 13 are flowcharts showing a processing routine for ISC control executed by the ECU 61 in the present embodiment.
This process is executed by an angle interruption every predetermined crank angle (180 ° CA in the present embodiment) on condition that the idle switch 20 is turned on.

When the processing shifts to this routine, first, in step 201, the ECU 61 sets the engine speed N
E, the cooling water temperature THW, the rotation fluctuation amount DLNE, the air conditioner operation determination flag XAC, and the upper limit guard value QACGD are read. Here, the rotation fluctuation amount DLNE is calculated in the same manner as in the first embodiment. The air conditioner operation determination flag XAC is set to “ON” when the air conditioner switch 38 is “ON”. The upper guard value QACGD is a value calculated by an upper guard value calculation routine described later. Each of the above values NE, T
EC that read HW, DLNE, XAC, QACGD
U61 proceeds to step 202.

In step 202, the ECU 61 calculates the basic control air amount Qi based on the one-dimensional map shown in FIG. 4 relating to the cooling water temperature THW, and stores the air amount Qi in the RAM 63, as in the first embodiment. Then, the process proceeds to step 203.

In step 203, the ECU 61 determines whether or not the air conditioner operation determination flag XAC is "ON". If it is determined that the air conditioner operation determination flag XAC is “ON”, the ECU 61 proceeds to step 2
Move to 04. In step 204, the ECU 61
Calculates a target rotation speed NTRG1 based on a predetermined one-dimensional map relating to the cooling water temperature THW. The target rotation speed NTRG1 is set higher when the air conditioner operation determination flag XAC is "OFF", that is, when the air conditioner 37 is stopped. The ECU 61 that has calculated the target rotation speed NTRG1 stores the target rotation speed NTRG1 in the RAM.
Then, the process goes to step 205.

In step 205, the ECU 61 calculates a feedback correction amount QII '. The feedback correction amount QII 'is a feedback value for correcting the air amount so that the engine speed NE becomes the calculated target speed NTRG1. The feedback correction amount QII' is stored in the ROM 64 relating to the deviation between the engine speed NE and the target speed NTRG1. Is obtained from a predetermined map stored in the. Then, the ECU 61 that has calculated the feedback correction amount QII '
The same correction amount QII 'is stored in the RAM 63 and the
Move to 6.

In step 206, the ECU 61 executes a routine to be described later (a routine for calculating a correction amount when the air conditioner is operating).
The air conditioner operating correction amount QAC1 is calculated based on The correction amount QAC1 is a correction amount of the air amount with respect to a load increase accompanying the operation of the air conditioner 37. As described later, in the calculation of the correction amount QAC1, an upper limit guard based on the upper limit guard value QACGD read in step 201 is applied. Air conditioner correction Q
The ECU 61 that has calculated AC1 proceeds to step 207.

In step 207, the ECU 61 calculates the corrected air amount Q by adding the calculated basic control air amount Qi, feedback correction amount QII 'and air conditioner operation correction amount QAC1. The ECU 61 that has calculated the corrected air amount Q stores the corrected air amount Q in the RAM 63 and proceeds to step 212.

In step 212, the ECU 61 sets the ISCV 41 corresponding to the calculated corrected air amount Q
Is calculated, and the routine proceeds to step 213. In step 213, the ECU 61 sets the calculated ISCV
The opening is output, and the subsequent processing is temporarily terminated.

On the other hand, if it is determined in step 203 that the air conditioner operation determination flag XAC is "OFF", the ECU 61 proceeds to step 208. In step 208, the ECU 61 determines the cooling water temperature THW.
Target rotation speed NTR based on a predetermined one-dimensional map
G2 is calculated. The target rotation speed NTRG2 is a rotation speed set to a lower value as the cooling water temperature THW increases. Further, the same rotation speed NTRG1 is set lower than when the air conditioner operation determination flag XAC is “ON”, that is, when the air conditioner 37 is operating. Then, the ECU 61 that has calculated the target rotation speed NTRG2 stores the target rotation speed NTRG2 in the RAM 63, and proceeds to step 20.
Move to 9.

In step 209, the ECU 61 calculates a feedback correction amount QII ". The feedback correction amount QII" is a feedback value for correcting the air amount so that the engine speed NE becomes the calculated target speed NTRG2. And a predetermined map stored in the ROM 64 regarding the difference between the engine speed NE and the target speed NTRG2. The ECU 61 that has calculated the feedback correction amount QII "
The correction amount QII "is stored in the RAM 63, and the process proceeds to step 21
Move to 0.

In step 210, the ECU 61 executes a routine to be described later (an air conditioner stoppage correction amount calculation routine).
Based on this, the air conditioner stoppage correction amount QAC2 is calculated. The ECU 61 that has calculated the air conditioner stoppage correction amount QAC2 is:
Move to step 211.

In step 211, the ECU 61 calculates the corrected air amount Q by adding the calculated basic control air amount Qi, feedback correction amount QII "and air conditioner stoppage correction amount QAC2. The ECU 61 stores the corrected air amount Q in the RAM 63 and proceeds to step 212.

In step 212, the ECU 61 sets the ISCV 41 corresponding to the calculated corrected air amount Q
Is calculated, and the routine proceeds to step 213. In step 213, the ECU 61 sets the calculated ISCV
The opening is output, and the subsequent processing is temporarily terminated.

The output of the ISCV opening thus calculated displaces the valve of the ISCV 41 in the rotation direction. As a result, the ISCV opening is controlled, and a required air amount (corrected air amount) Q is supplied.

Next, the air conditioner operating correction amount QAC1
Will be described with reference to FIG. FIG. 12 is a flow chart showing an "air conditioner operation correction amount calculation routine" for calculating and determining the air conditioner operation correction amount QAC1.

When the processing shifts to this routine, first, in step 221, the ECU 61 determines the rotation fluctuation amount D
It is determined whether LNE is "0" or more. Here, when it is determined that the rotation fluctuation amount DLNE is equal to or greater than “0”, the ECU 61 determines that the engine speed NE has decreased during the operation of the air conditioner 37, and the ECU 61 proceeds to step 222.

In step 222, the ECU 61 adds a predetermined increase / decrease amount ΔQ ′ to the previous expected correction amount QAC1 (i−1) for the load increase accompanying the operation of the air conditioner 37,
The current expected correction amount QAC1 (i) is calculated. The ECU 61 then calculates the calculated expected correction amount QAC1
(I) is stored in the RAM 63, and the process proceeds to step 223.

In step 223, the ECU 61 sets the estimated correction amount QAC1 (i)
An amount obtained by adding a predetermined amount A stored in advance in M64 (QAC
It is determined whether 1 (i) + A) is equal to or greater than the upper limit guard value QACGD read in step 201. When the operation of the air conditioner 37 is confirmed, the predetermined amount A is used for the air conditioner operating correction amount QA at once.
C1 is a correction amount for increasing the correction air amount Q. By the increase of the predetermined amount A, the load increase when operating the air conditioner 37 is reduced, and the engine speed NE is increased.
Of rotation is reduced. Here, the expected correction amount Q
AC1 (i) plus the predetermined amount A (QAC (i)
+ A) is determined to be smaller than the upper limit guard value QACGD, the ECU 61 proceeds to step 225,
The correction amount QAC1 at the time of operating the air conditioner is set to
(I) + A) and the subsequent processing is temporarily terminated.

Also, in step 223, the quantity (Q
If AC1 (i) + A) is determined to be greater than or equal to the upper guard value QACGD, the ECU 61 proceeds to step 22.
Then, the process proceeds to step S4, where the air conditioner operating correction amount QAC1 is set to the upper limit guard value QACGD, and the subsequent processing is temporarily terminated.

If the engine speed NE decreases during the operation of the air conditioner 37 by the processing of steps 222 to 225, the upper limit guard value QAC
Air conditioner operating correction amount QAC1 within the range of GD as upper limit
Is gradually increased.

On the other hand, if it is determined in step 221 that the rotation fluctuation amount DLNE is less than “0”, it is determined that the engine speed NE is increasing during operation of the air conditioner 37, and the ECU 61 proceeds to step 226. .

In step 226, the ECU 61 subtracts the predetermined increase / decrease ΔQ 'from the previous expected correction amount QAC1 (i-1) for the load increase accompanying the operation of the air conditioner 37, and obtains the current expected correction amount QAC1 (i ) Is calculated.
Then, the ECU 61 calculates the calculated expected correction amount QAC.
1 (i) is stored in the RAM 63, and the process proceeds to step 227.

In step 227, the ECU 61 calculates the amount (QAC1 (i) + A) obtained by adding the predetermined amount A to the calculated current expected correction amount QAC1 (i),
It is determined whether or not the size is equal to or smaller than the lower limit guard value QACgd stored in the OM 64 in advance. Note that the lower limit guard value QACgd is a value that is set in order to maintain the air conditioner operating correction amount QAC1 when the air conditioner 37 is operating at a predetermined amount (QACgd) or more and prevent engine stall from occurring. Here, the current estimated correction amount QAC1
The quantity (QAC1 (i) +
If it is determined that A) is larger than the lower limit guard value QACgd, the ECU 61 proceeds to step 229 and sets the air conditioner operation correction amount QAC1 to the amount (QAC1 (i)).
+ A) and the subsequent processing ends once.

In step 227, the quantity (Q
If it is determined that AC1 (i) + A) is equal to or smaller than the lower limit guard value QACgd, the ECU 61 proceeds to step 22.
Then, the process proceeds to step S8, where the air conditioner operation correction amount QAC1 is set to the lower limit guard value QACgd, and the subsequent processing is temporarily terminated.

If the engine speed NE is increasing during the operation of the air conditioner 37 by the processing of steps 226 to 229, the lower limit guard value QAC
Air conditioner operating correction amount QAC1 within the range of gd as the lower limit
Is gradually reduced.

Next, the air conditioner stoppage correction amount QAC2
Will be described with reference to FIG. FIG. 13 is a flowchart showing an "air conditioner stoppage correction amount calculation routine" for calculating and determining the air conditioner stoppage correction amount QAC2.

When the process proceeds to this routine, first, in step 231, the ECU 61 subtracts the predetermined increase / decrease amount ΔQ ′ from the previous estimated correction amount QAC2 (i−1), and the current estimated correction amount QAC2 (i). Is calculated.
Then, the ECU 61 calculates the calculated expected correction amount QAC.
2 (i) is stored in the RAM 63, and the process proceeds to step 232.

At step 232, the ECU 61 determines whether or not the calculated current estimated correction amount QAC2 (i) is smaller than "0". Here, if it is determined that the current estimated correction amount QAC2 (i) is larger than “0”, the ECU 61 proceeds to step 234, and sets the air conditioner stoppage correction amount QAC2 to the expected correction amount QAC2 (i). Then, the subsequent processing is temporarily ended.

If it is determined in step 232 that the expected correction amount QAC2 (i) is equal to or smaller than "0", the ECU 61 proceeds to step 233 and sets the air conditioner stoppage correction amount QAC2 to "0". Then, the subsequent processing is temporarily ended.

With the processing of steps 231 to 234, the air conditioner stoppage correction amount QAC2 is gradually reduced within the range of "0" as the lower limit as the air conditioner 37 stops.

Next, the "upper guard value calculation routine" for calculating and determining the upper guard value QACGD will be described with reference to FIG. This process is executed by an air conditioner control interrupt every time the air conditioner switch 38 is switched from "off" to "on". That is, the upper limit guard value QAC calculated in the routine
GD is maintained at the same value until the next time the air conditioner switch 38 is turned on.

When the processing shifts to this routine, first, in step 251, the ECU 61 determines that the rotational fluctuation amount D
Read LNE. It should be noted that the rotation fluctuation amount DLNE read at this time indicates that the air conditioner switch 38 is "ON".
It is the amount of rotation fluctuation calculated first after the set timing. ECU 61 reading the rotation fluctuation amount DLNE
Moves to step 252.

In step 252, the ECU 61 determines whether or not the rotation fluctuation amount DLNE is equal to or greater than B (rpm). Here, when it is determined that the rotation fluctuation amount DLNE is smaller than B, it is determined that the load increase has been gradual due to the operation of the air conditioner 37, and the ECU 61 determines in step 2
Go to 53. It should be noted that such a gradual increase in the load may be caused by, for example, the operation of the air conditioner 37 when the air conditioner 37 operates.
7 occurs when the difference between the target temperature and the actual vehicle interior temperature is small.

In step 253, the upper limit guard value QACGD is set to the smaller value QACGDL (liter per second), and the subsequent processing is temporarily terminated. Incidentally, the smaller upper limit guard value QACGDL is a value set to prevent overcorrection of the air amount.

If it is determined in step 252 that the rotation fluctuation amount DLNE is equal to or greater than B, it is determined that the load increase accompanying the operation of the air conditioner 37 has been sharply performed, and the ECU determines
61 moves to step 254. Such a sudden increase in load occurs, for example, when the difference between the target temperature of the air conditioner 37 and the actual vehicle interior temperature during operation of the air conditioner 37 is large.

In step 254, the upper limit guard value QACGD is set to the larger value, QACGDH (liter per second), and the subsequent processing is temporarily terminated. Incidentally, the larger upper limit guard value is a value set to supply a large amount of required air at a required timing.

The calculated upper limit guard value QA
As described above, the CGD is read in step 201 (FIG. 11) and subjected to the ISC control.
Next, an ISC control mode at the time of operating the air conditioner 37 in the present embodiment, which is executed through each of these routines, will be described with reference to FIGS. Note that FIG.
16 and FIG. 16, respectively, the load suddenly increases due to the operation of the air conditioner 37, and the rotation drops (rotation fluctuation amount DLNE).
FIG. 9 is a time chart showing an ISC control mode when is large and when the load increase accompanying the operation of the air conditioner 37 is gradual and the rotation drop (rotation fluctuation amount DLNE) is small. 15 and 16, each diagram (a) shows the transition of the air conditioner operation determination flag XAC, each diagram (b) shows the transition of the engine speed NE, and each diagram (c) shows the transition of the air conditioner operation correction amount QAC1. Are respectively shown.

First, a case where the load increases rapidly due to the operation of the air conditioner 37 will be described with reference to FIG. As described above, such a sudden increase in load occurs when the difference between the target temperature of the air conditioner 37 and the actual temperature inside the vehicle when the air conditioner 37 is operating is large.

First, at time t31, the air conditioner 37
Is activated, and the air conditioner operation determination flag XAC is switched from “off” to “on”. The air conditioner 3
7, the engine speed N
The air amount correction for idling up to the target rotation speed NTRG1 in which E is set higher than the initial target rotation speed NTRG2 starts. At this time, the air conditioner operating correction amount QAC1 is immediately increased by the predetermined amount A. The predetermined amount A
As described above, only the increase in the air conditioner operating correction amount QAC1 reduces the load increase when the air conditioner 37 is operated, and reduces the decrease in the engine speed NE.

After time t31, the air conditioner operating correction amount QAC1 is increased by the predetermined increase / decrease amount ΔQ ′ in response to the rotation drop of the engine speed NE (the rotation fluctuation amount DLNE is a positive value) over time. Is gradually increased. In addition, since the increase in load accompanying the operation of the air conditioner 37 occurs rapidly, a larger guard value (QACGD = QACGDH) is set for the correction amount QAC1. Due to the gradual increase of the air conditioner operating correction amount QAC1, the time t3
When the correction amount QAC1 reaches the larger guard value QACGDH in 2, the gradual increase of the correction amount QAC1 is stopped.

From time t32 to time t33, the engine speed NE decreases with time. However, the correction amount QA at the time of operating the air conditioner is
Since C1 has reached the guard value QACGDH, the air conditioner operating correction amount QAC1 is equal to the guard value QACGD.
H is maintained.

After time t33, the air conditioner operating correction amount QAC1 is gradually reduced by the predetermined increase / decrease amount ΔQ ′ in response to the recovery from the rotation drop of the engine speed NE (the rotation fluctuation amount DLNE is a negative value). Is done. Due to the gradual decrease of the air conditioner operating correction amount QAC1, when the correction amount QAC1 reaches the lower limit guard value QACgd at time t34,
The gradual decrease of the correction amount QAC1 is stopped.

After time t34, until time t35, it corresponds to recovery from a decrease in the engine speed NE with a lapse of time. However, since the air conditioner operating correction amount QAC1 has reached the lower limit guard value QACgd, the air conditioner operating correction amount QAC1 is maintained at the same guard value QACgd.

Further, after the time t35, the rotation of the engine speed NE drops again with the lapse of time (the rotation fluctuation amount DL).
NE is a positive value), the air conditioner operating correction amount QAC1 is gradually increased by the predetermined increase / decrease amount ΔQ ′. With the gradual increase of the air conditioner operating correction amount QAC1, the rotation drop of the engine speed NE stops, and at time t36, the engine speed NE becomes the target speed NTRG1 in a state where the load increase due to the operation of the air conditioner 37 is offset. Converge.

As described above, when the load increase accompanying the operation of the air conditioner 37 is sharply generated and the rotation of the engine speed NE is greatly reduced, the air conditioner operating correction amount QAC1 is corrected to the larger guard value QACGDH as much as possible. it can. Therefore, by supplying sufficient air and supplying sufficient fuel corresponding to the air, sufficient torque that can cope with the operation of the air conditioner 37 can be obtained. From the above,
When the rotation drop of the engine speed NE is large,
A quick response is taken while preventing engine stalls.

Next, a case where the load fluctuation accompanying the operation of the air conditioner 37 occurs gradually will be described with reference to FIG. As described above, such a gradual increase in the load occurs when, for example, the difference between the target temperature of the air conditioner 37 and the actual temperature inside the vehicle during operation of the air conditioner 37 is small.

First, at time t41, the air conditioner 37
Is activated, and the air conditioner operation determination flag XAC is switched from “off” to “on”. The air conditioner 3
7, the engine speed N
The start of the air amount correction for idling up to the target rotation speed NTRG1 in which E is set higher than the initial target rotation speed NTRG2 is the same as when the load on the air conditioner 37 suddenly increases. At this time, the air conditioner operating correction amount QAC1 is immediately increased by the predetermined amount A.

After the time t41, the air conditioner operating correction amount QAC1 is increased by the predetermined increase / decrease amount ΔQ ′ in response to the rotation drop of the engine speed NE over time (the rotation fluctuation amount DLNE is a positive value). Is gradually increased. Since the load increase accompanying the operation of the air conditioner 37 is gradual, a smaller guard value QACGDL is set for the correction amount QAC1. When the correction amount QAC1 at the time of operating the air conditioner gradually increases and reaches the smaller guard value QACGDL at time t42, the increase of the correction amount QAC1 is stopped.

[0140] From time t42 to time t43, the rotation speed of the engine rotational speed NE continuously decreases with time. However, the correction amount QA at the time of operating the air conditioner is
Since C1 has reached the guard value QACGDL, the air conditioner operating correction amount QAC1 is equal to the guard value QACGD.
L is maintained.

After time t43, the air conditioner operating correction amount QAC1 is gradually decreased by the predetermined increase / decrease amount ΔQ ′ in response to the recovery from the rotation drop of the engine speed NE (the rotation fluctuation amount DLNE is a negative value). Is done. Due to the gradual decrease of the air conditioner operating correction amount QAC1, when the correction amount QAC1 reaches the lower limit guard value QACgd at time t44,
The gradual decrease of the correction amount QAC1 is stopped.

[0142] From time t44 to time t45, the engine speed NE corresponds to a recovery from a drop in the engine speed NE over time. However, since the air conditioner operating correction amount QAC1 has reached the lower limit guard value QACgd, the air conditioner operating correction amount QAC1 is maintained at the same guard value QACgd.

Further, after the time t45, the rotation of the engine speed NE drops again with the lapse of time (the rotation fluctuation amount DL).
NE is a positive value), the air conditioner operating correction amount QAC1 is gradually increased by the predetermined increase / decrease amount ΔQ ′. With the gradual increase of the air conditioner operating correction amount QAC1, the rotation drop of the engine speed NE stops, and at time t46, the engine speed NE reaches the target speed NTRG1 in a state where the load increase due to the operation of the air conditioner 37 is offset. Converge.

As described above, when the load increase accompanying the operation of the air conditioner 37 is gradual, and the rotation drop of the engine speed NE is small, the correction of the upper limit of the air conditioner operation correction amount QAC1 is restricted to the smaller guard value QACGDL. Is done.
Accordingly, excessive correction of the air conditioner operating correction amount QAC is avoided, and the engine speed NE quickly converges to the target speed NTRG1.

As described in detail above, according to the present embodiment, the following effects can be obtained. -When the rotation speed of the engine speed NE is largely reduced, it is possible to quickly converge to the target engine speed NTRG1 that has been idled up while preventing the occurrence of engine stall.

When the rotation drop of the engine speed NE is small, the target rotation speed at which the idle speed is quickly increased by avoiding excessive correction of the air conditioner correction amount QAC1, that is, the correction air amount Q, It can be converged to NTRG1.

The present embodiment is not limited to the above, but may be modified as follows. In the present embodiment, the predetermined amount A and the increase / decrease amount ΔQ ′
Is a constant. On the other hand, at least one of the predetermined amount A and the increase / decrease amount ΔQ ′ may be a variable according to the operating state of the engine 1. For example, the rotational fluctuation amount DLNE
Is large (when the rotational speed drop of the engine speed NE is large), the predetermined amount A or the increase / decrease amount ΔQ ′ is set to be large, so that a rapid response to the rotational speed drop can be taken.

In the present embodiment, it is assumed that the air conditioner 37 operates as a load increase, and the load increase due to the operation of the air conditioner 37 is canceled to make the engine speed NE higher than the initial target speed NTRG2. IS that idles up to a higher target rotational speed NTRG1
C control was performed. On the other hand, for example, when the same ISC control with idle-up is performed when the power steering 52 is operated, the same ISC control is performed when the load increases due to the operation of the power steering 52.
C control may be performed.

Other elements that can be changed in common to the above embodiments include the following. In each of the above embodiments, the case where the power steering 52 operates or the case where the air conditioner 3
7 has been described in the case where the ISC 7 operates. On the other hand, for example, when an automobile equipped with the engine 1 is equipped with an automatic transmission, the same ISC control is applied to the case where the load increases when the shift position of the transmission is switched from the neutral position to the drive position. May be executed. Further, when the external loads including the power steering 52 and the air conditioner 37 are simultaneously operated, the ISC control may be executed based on a combination of the corresponding routines.

In the above embodiments, two upper limit guard values are provided. On the other hand, three or more upper limit guard values may be provided. Further, the rotation fluctuation amount D
A map of the upper limit guard value for LNE may be provided, and the upper limit guard value may be calculated according to the operating state of the engine 1.

In the above embodiments, the operation amount of the external load is determined based on the rotation fluctuation amount DLNE. On the other hand, the operation amount of the external load may be directly determined based on, for example, electric power output from the alternator of the engine 1 to the load. Then, an upper limit guard value is set according to the output value from the alternator to the external load.

In the above embodiments, the rotary solenoid type ISCV 41 is employed, but a duty VSV (vacuum switching valve) type or a step motor type ISCV may be employed.

In each of the above embodiments, the ISC control of the gasoline engine has been described, but this may be a diesel engine. In this case, the engine speed is adjusted based on the fuel injection amount supplied to the engine.

Next, technical ideas other than the claims that can be understood from the above embodiments are described below together with their effects. In the idle speed control device for an internal combustion engine according to any one of claims 1 to 4, the guard value setting means also sets a lower limit guard value for preventing stall occurrence of the engine. An idle speed control device for an internal combustion engine. According to this configuration, the guard value setting means also sets a lower limit guard value for preventing the engine from stalling. Therefore, occurrence of engine stall in the correction of the air amount can be prevented.

The external load is a power steering;
The idle speed control device for an internal combustion engine according to any one of claims 1 to 4, which is at least one of an air conditioner and an automatic transmission. According to this configuration, idle speed control suitable particularly for operation of an external load in which the amount of operation tends to be gradual is realized.

An idle speed control device for an internal combustion engine that corrects a fuel injection amount supplied to the internal engine according to the operation of an external load when the internal combustion engine is idling to control the engine speed to a required target speed. An idle speed control device for an internal combustion engine, comprising: a guard value setting means for calculating and setting each upper limit guard value corresponding to the operation amount of the external load with respect to the correction amount of the supplied fuel injection amount. . According to this configuration, the upper limit guard value is set according to the operation amount of the external load. Therefore, it is possible to appropriately correct the fuel injection amount for promptly converging the engine speed to the required target speed without depending on the speed of the operation of the external load.

[0157]

According to the first aspect of the present invention, a suitable air amount correction for promptly converging the engine speed to the required target speed regardless of the speed of the operation of the external load. Can be.

According to the second aspect of the present invention, when the fluctuation amount of the engine speed at a predetermined timing is large, that is, when the external load is suddenly operated, the engine speed is quickly converged to the required target speed. Can be.

When the variation of the engine speed at the predetermined timing is small, that is, when the external load operates slowly, the air amount is prevented from being excessively corrected, and the air amount is quickly corrected. It can be converged to the rotation speed.

According to the third aspect of the present invention, the calculation load of the upper limit guard value can be greatly reduced as the guard value setting means. According to the fourth aspect of the present invention, even when the external load is suddenly operated, the stall of the engine caused by the external load is prevented, and the engine speed is quickly converged to the required target rotational speed. Can be.

Further, even when the external load operates slowly, it is possible to avoid excessive correction of the air amount and to quickly converge to the target rotational speed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of an engine system to which a first embodiment of an idle speed control device according to the present invention is applied;

FIG. 2 is a block diagram showing an electrical configuration of the embodiment.

FIG. 3 is a flowchart showing an ISC control routine according to the embodiment;

FIG. 4 is a map showing a relationship between a cooling water temperature and a basic control air amount.

FIG. 5 is a flowchart showing a power steering correction amount calculation routine according to the embodiment;

FIG. 6 is a flowchart showing a power steering correction amount calculation routine according to the embodiment;

FIG. 7 is a flowchart showing an upper limit guard value calculation routine according to the embodiment;

FIG. 8 shows a state I during power steering operation of the embodiment.
4 is a time chart showing an SC control mode.

FIG. 9 shows a state I during power steering operation of the embodiment.
4 is a time chart showing an SC control mode.

FIG. 10 shows a second example of the idle speed control device according to the present invention.
1 is a schematic diagram showing an outline of an engine system to which an embodiment of the present invention is applied.

FIG. 11 is a flowchart showing an ISC control routine of the embodiment.

FIG. 12 is a flowchart showing a routine for calculating a correction amount when the air conditioner is operating according to the embodiment;

FIG. 13 is a flowchart showing an air conditioner stoppage correction amount calculation routine according to the embodiment;

FIG. 14 is a flowchart showing an upper-limit guard value calculation routine according to the embodiment;

FIG. 15 is a time chart showing an ISC control mode during operation of the air conditioner according to the embodiment.

FIG. 16 is a time chart showing an ISC control mode during operation of the air conditioner of the embodiment.

FIG. 17 shows a state I during power steering operation of a conventional device.
4 is a time chart showing an SC control mode.

FIG. 18 shows a state I during power steering operation of a conventional device.
4 is a time chart showing an SC control mode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 20 ... Idle switch, 27 ... Crank angle sensor, 37 ... Air conditioner, 38 ... Air conditioner switch, 41 ... ISCV, 51 ... Steering, 52 ... Power steering, 53 ... Power steering hydraulic switch, 61 ... ECU.

Claims (4)

[Claims] An idle speed control device for an internal combustion engine that corrects an amount of air supplied to the internal engine in response to an operation of an external load during idling of the internal combustion engine to control the engine speed to a required target speed. An idle speed control device for an internal combustion engine, comprising: a guard value setting means for calculating and setting each upper limit guard value corresponding to the operation amount of the external load with respect to the correction amount of the supplied air amount. 2. The system according to claim 1, wherein the guard value setting means obtains an operation amount of the external load based on a fluctuation amount of the engine speed at a predetermined timing. The idle speed control device for an internal combustion engine according to claim 1, wherein the value is calculated and set. 3. The guard value setting means has two kinds of upper limit guard values having different sizes in advance, and stores the upper limit guard values in accordance with a fluctuation amount of the engine speed at the predetermined timing.
3. The idle speed control device for an internal combustion engine according to claim 2, wherein one of upper limit guard values is selectively set. 4. The upper limit guard value on the larger side of the two types of upper limit guard values is set as a value capable of supplying a large amount of required air at a required timing, and the upper limit guard value on the smaller side is the above upper limit guard value. The idle speed control device for an internal combustion engine according to claim 3, wherein the value is set as a value capable of preventing overcorrection of the air amount.