JPH02252938A - Idle revolution speed controller for engine - Google Patents

Abstract

PURPOSE:To improve the idling stability by reducing the feedback quantity in the ignition timing feedback control by reducing the width of the insensitive band in the intake quantity feedback control during the ignition timing feedback control for an engine. CONSTITUTION:The ignition timing of an engine is adjusted by an ignitor A, and the intake quantity is adjusted by an idle control valve B. Ignition timing correction F and intake quantity correction G are carried out so that the engine revolution speed C becomes equal to an aimed value D on the basis of the difference E between the engine revolution speed C and the aimed value D of the idle revolution speed. When intake quantity correction G is carried out, the insensitive band setting H having a prescribed width is carried out for the aimed value D of the idle revolution speed. When ignition timing correction F is carried out, an insensitive band change instruction I for reducing the width of the insensitive band is outputted into the insensitive band setting H. In other words, the feedback quantity in the ignition timing feedback control is reduced. Thus, the stability in idling can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an engine idle speed control device,
In particular, it relates to a device in which the ignition timing and the intake air amount are feedback-controlled so that the target idle speed is achieved, and the dead zone of the intake air amount feedback control is narrowed while the ignition timing feedback control is being executed.

[Prior art]

BACKGROUND ART Conventionally, among idle speed control devices that control the engine speed so as to reach a target idle speed, devices that precisely feedback control the intake air amount via an ISO valve have been widely put into practical use.

This feedback control based on intake air volume lacks responsiveness because it takes a long time after the intake air volume is changed until it is reflected in the engine speed, and it is not sufficient to cope with cases where the engine speed fluctuates rapidly and frequently. The disadvantages are that there is no power, and that hunting is likely to occur due to low response.

Therefore, recently, ignition timing feedback control with excellent responsiveness has been combined in parallel with the intake air amount feedback control using the ISC valve, and the intake air amount and ignition timing are feedback-controlled based on the deviation between the actual rotation speed and the target idle rotation speed. An idle speed control device has been proposed.

For example, in Japanese Patent Application Laid-open No. 61-53544, the amount of air-fuel mixture to the engine is controlled so that the engine speed becomes the target idle speed, and the deviation between the engine speed and the target idle speed and the engine speed are further disclosed. A technique is described in which the ignition timing is controlled according to at least one of the amount of variation in the number.

In the engine speed control technology described in the above publication,
Based on the deviation between the actual rotation speed and the target rotation speed or the amount of variation in the engine rotation speed, intake air amount control and ignition timing control are individually executed in parallel.

In addition, in the feedback control of the intake air amount using ISO pulp, ±ΔN, (ΔN
A dead zone with a width of m = 20-30 rpm) is provided.

[Problem to be solved by the invention]

As mentioned above, in conventional idle speed control devices, feedback control of ignition timing, which has excellent responsiveness, and feedback control of intake air volume, which has low responsiveness, are performed independently and individually. When the engine speed N falls below the target idle speed N0 due to a load acting on it, such as when the engine is turned on, the deviation ΔN (ΔN=No
Ignition timing feedback control and intake air amount feedback control are performed based on N), but the ignition timing feedback control, which has excellent responsiveness, progresses rapidly and the engine speed increases due to the ignition timing being corrected to the advanced side. Deviation ΔN
decreases, and feedback control of the intake air amount is performed substantially in parallel with this. As a result, when ΔN#0 is reached, the ignition timing control and intake air amount control maintain their respective states, so the ignition timing advance angle correction amount is fixed to that value.

To provide a supplementary explanation with reference to FIG. 1O, during idling, the ignition timing in the ignition timing/torque characteristics is approximately at θ near the center of the linear region A of the characteristics. Although it is desirable to set the ignition timing so that the ignition timing can be freely corrected in the direction of increasing torque or decreasing torque according to load fluctuations, as mentioned above, the ignition timing is not advanced. If the ignition timing is corrected to θ and fixed at that value θ, the allowable range in which the ignition timing can be corrected to the side where the rotation speed increases (torque increases) becomes narrower, and ignition timing feedback control becomes effective when the load increases. The problem is that you can't do it.

This means that when ΔN<O, ignition timing control works and ΔN
eo, and the ignition timing is fixed at a retarded θ. In this case, the torque value is low, resulting in a disadvantage in terms of fuel efficiency.

On the other hand, when a large load acts and a large deviation ΔN occurs, the ignition timing is advanced to the best torque advance angle θ□7 by ignition timing feedback control with excellent responsiveness, and from then on the ignition timing is set at that value θ□ It is fixed at 7.

At this time, even if ΔN≠0, if the deviation ΔN enters the dead zone of the intake air amount feedback control, the intake air amount feedback control will also be maintained in that state, so that ΔN≠O, that is, the engine speed will become the target idle speed. Even though this is not the case, there is a problem in that both the ignition timing feedback control and the intake air amount feedback control become fixed.

As explained above, various problems arise when the ignition timing feedback control and the intake air amount feedbank control each have a deviation ΔN.
This is a problem that inevitably arises when operations are carried out independently based on the following.

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine idle speed control device that can improve idle stability and fuel efficiency during idle operation by reducing the amount of feedback in ignition timing feedback control.

[Means for Solving the Problems] An engine idle speed control device according to the present invention includes an ignition timing adjusting means for adjusting ignition timing, an intake air amount adjusting means for adjusting an intake air amount, and an engine idle speed control device for controlling an engine's actual engine speed. and an ignition timing adjustment means that receives the output from the rotation speed detection means and adjusts the actual rotation speed to the target idle rotation speed based on the deviation between the actual rotation speed and the target idle rotation speed. In an engine idle speed control device comprising an ignition timing control means and an intake air amount control means that perform feedback control of the intake air amount adjusting means and the intake air amount adjusting means, the intake air amount feedback control by the intake air amount control means includes a predetermined value for the target idle speed. dead zone setting means for setting a width dead zone; and dead zone changing means for instructing the dead zone setting means to narrow the dead zone during execution of feedback control of ignition timing based on the output from the ignition timing control means. It is equipped with the following.

[Effect]

In the engine idle speed control device according to the present invention, the deviation ΔN (ΔN=N, - When N) occurs,
Based on the deviation ΔN, the ignition timing control means and the intake air amount control means respectively perform ignition timing feedback control and intake air amount feedback control so that ΔN=O.

First, intake air amount feedback control is executed when the deviation ΔN occurs, and when ΔN>0, the intake air amount is corrected to increase, and when ΔNeo, the intake air amount is corrected to decrease.During this period, the dead band setting means controls the intake air amount control means. In contrast, a dead zone of a predetermined width is set for the target idle speed,
Intake air amount feedback control continues as long as the actual rotational speed N does not fall within a dead zone of a predetermined width.

In this way, as the deviation ΔN decreases, the ignition timing control means starts ignition timing feedback control, and ΔN decreases.
When N>O, the ignition timing is corrected to the advance side, and when ΔN<0, the ignition timing is corrected to the retard side.

If, as in the prior art, the dead band of the intake air amount feedback control is maintained at a predetermined width, if the deviation ΔN enters the dead band, the intake air amount feedback control will stop, and from then on, only the ignition timing feedback control will be performed. ΔN#0
Since the control is executed until ΔN=0, the ignition timing will be fixed at a timing that is biased towards the advance side or the retard side.

However, in the present invention, when the ignition timing feedback control is started, the dead zone of the intake air amount feedback control is changed to a narrow dead zone by the dead zone changing means,
While the ignition timing feedback control is being executed, the dead zone is maintained in a narrow width, and the ignition timing feedback control and intake air amount feedback control are executed in parallel until the deviation ΔN enters the narrow range dead zone, and the deviation ΔN is kept in the narrow range. After entering the dead zone, ignition timing feedback control continues.

That is, hunting can be prevented by setting a wide dead zone while only the intake air amount feedback control with low responsiveness is being executed. Moreover, hunting does not occur even if the dead zone of intake air amount feedback control is set narrowly during execution of highly responsive ignition timing feedback control.

As mentioned above, since the dead zone is changed to be narrower and ignition timing feedback control and intake air amount feedback control are performed in parallel, the feedback amount of ignition timing feedback control is reduced by the amount shared by intake air amount feedback control, and ΔN#O At this point, it is possible to prevent the ignition timing from shifting significantly toward the advance or retard side, and it is possible to prevent fuel consumption from deteriorating during idling.

〔Effect of the invention〕

According to the engine idle speed control device according to the present invention, as explained in the above [Operation] section, the dead zone setting means and the dead zone changing means are provided, and the intake air amount feedback control is controlled while the ignition timing feedback control is being executed. By narrowing the dead zone, the amount of feedback for ignition timing feedback control can be reduced, improving idle stability against fluctuations in actual rotation speed due to changes in external load acting on the engine, and retarding the ignition timing. It is possible to prevent fuel consumption from deteriorating during idling due to excessive shift to the side.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

This embodiment is a case in which the present invention is applied to an idle speed control device for a vertical four-cylinder engine for an automobile. 5, intake valve 5a
, the exhaust boat 6, the exhaust valve 5a, the spark plug 7, the injector 8, the intake passage 9, the exhaust passage IO, etc. are the same as those of a general automobile engine, so a detailed explanation thereof will be omitted.

As shown in FIG. 1, the cylinder block 1 is provided with a water temperature sensor 12 that detects the temperature of cooling water in its water jacket la, and a hot wire that detects the amount of intake air is provided at the upstream portion of the intake passage 9. type air flow meter 14
is interposed, and a throttle valve 15 is provided in the middle of the intake passage 9.
The throttle valve 15 is provided with a throttle opening sensor 16 that detects the opening of the throttle valve 15, and an eye and dollar switch that is turned ON when the throttle valve 15 is fully closed. Signals from the opening sensor 16 and the idle switch are input to the control unit 11. A bypass passage 17 that bypasses the throttle valve 15 is provided, and this bypass passage 17 has an idle speed control (
An idle control valve 18 controlled by a linear solenoid for ISC) is provided, and the opening degree of the idle control valve 18 is controlled by the control unit 11, so that the amount of intake air supplied from the bypass passage 17 is precisely controlled. Ru.

Ignition device 1 for igniting the four spark plugs 7 of the engine E in a predetermined order and at controlled timing
9 and a distributor 20 are provided, and the ignition device 1
Reference numeral 9 includes an ignition control circuit and an ignition coil, and generates a high voltage in response to signals TGTS and IGW that command ignition timing and energization time from the control unit 11, and the high voltage is transmitted to the four spark plugs 7 by a distributor 20. Power is distributed to

The distributor 20 includes a disk fixed to a rotating shaft that rotates in synchronization with the crankshaft and an electromagnetic pickup, and a crank angle signal C8 is generated every 180" rotation of the crankshaft.
A crank angle sensor is provided that outputs this to the control unit 11.

Further, the control unit 11 receives signals from a neutral position switch 22 provided in the transmission, and drive switches 23 for the air conditioner, power steering, electrical loads, etc. that act as external loads for the engine E.
Signals from 24 etc. are also output.

As shown in FIG. 2, the control unit 11 receives detection signals from various sensors 12, 14, 16 and signals from various switches 21 to 24, etc., and performs A/D conversion as necessary. Manual port 25 for waveform shaping
and a bus 26 including a data bus, an address bus, etc.
CPU27 (central processing unit) and ROM28 (read/
only memory) and RAM29 (random access
It is equipped with a microcomputer consisting of a memory), an output boat 30, a drive circuit 31 for the injector 8, a drive circuit 32 for the idle control valve 18, a drive circuit 33 for the ignition device 19, etc. In the ROM 28, a control program for idle speed control, which will be described later, various memory maps necessary for this control, and other control programs and memory maps necessary for controlling the engine E are input and stored in advance.

Here, as shown in the functional block diagram of FIG. 3, the idle speed control device of the present application controls the engine speed so that the engine speed N0 becomes the target idle speed N0 when the engine E is in the idle operating state. The ignition timing and intake air amount are feedback-controlled based on the deviation between the rotational speed N and the target idle rotational speed N0, and the dead zone of the intake air amount feedback control is narrowed while this ignition timing feedback control is being executed. It is something.

The idle rotation speed control routine executed by the control unit 11 will be explained based on the flowcharts shown in FIGS. 4 to 6.

This idle rotation speed control is executed by interrupt processing every time the crank angle signal C3 is input, that is, every time the crankshaft rotates 180 degrees. In addition, 5i (i=1.2.3...
) indicates each step.

When this control is started each time the crank signal C8 is input while the engine E is running, the water temperature sensor 12 detects the cooling water'/!
A T h w is read (Sl), and then the water temperature T6 is determined from the memory map shown in FIG. 7 stored in the ROM 28.
1 is used to calculate the target idle rotation speed N0 (S2
). Next, the crank angle signal C3 is read and the engine speed N8 is calculated (S3), and then the rotation speed deviation ΔN (
However, ΔN=N.

-N,) is calculated (S4). Next, by determining whether the engine speed N is below a predetermined value (for example, 800 rpm), the neutral position switch 22 is ON, and the idle switch is ON, the operating state of the engine E is determined to be idle. (S5)
, if Yes, it is determined whether ΔNl<KNI (S6
) Thereafter, a flag F8 indicating execution of intake air amount feedback control is set (S7). On the other hand, if it is not in the idle state or if 1ΔN<KNI is not established even in the idle state, the process moves to S8, and in S8 the flag Fl
Flag F indicating execution of &J and ignition timing feed hack control. Both are given cents, and the process moves from S8 to 312, which will be described later.

The above KN indicates a predetermined range of the deviation ΔN in which intake air amount feed bank control is executed, as shown in FIG. 9, and KNE, which will be described later, indicates a predetermined range in which ignition timing feedback control is executed. , KNI > KNE.

Therefore, in S6, it is determined whether the deviation ΔN is within the range for executing intake air amount feedback control.

The process moves from S7 to 89, and it is determined whether 1ΔNl<KNE, that is, whether the deviation ΔN is within the range for executing ignition timing feedback control (S9), and if No, the flag FE is reset (SIO) or Yes
When , FE is set (Sll).

Next, the intake air amount feedbank control in S12, the ignition timing feedbank control in 813, and the fuel injection control in 314 are executed in order, and the process returns to the main routine.

FIG. 5 shows the intake air amount feedback control routine at S12. First, it is determined whether flag F is set (S20), and NO.

In other words, when the intake air amount feedback control is not required to be executed, the duty value Dt of the drive pulse supplied to the linear solenoid of the idle control valve 18 is D.
t=CI (however, C8 is a predetermined constant) is set (52
1), then proceed to S29.

On the other hand, when flag F is set, it is determined whether flag FE is set (S22).
1. When No, that is, when the ignition timing feedbank control is not in a state where it should be executed, the dead band NR of the intake air amount feedback control is a predetermined wide dead band N shown in FIG.
R, (S23), and then the process moves to S25.

When the flag FE is set, that is, when the ignition timing feed hack control is executed, the dead zone NR is set to a dead zone NRZ, which is narrower than NR1 and has a width of about half (
S24), and then a determination is made regarding the value of the deviation ΔN (S24).
25), when ΔN>NR (that is, when Ne is significantly smaller than N), the duty value Dt is set to the value obtained by adding a predetermined integral constant I to the previous duty value in S26, and when 1ΔN≦NR When the deviation ΔN is within the dead band NR, the intake air amount feed hack control is not executed, so the duty value is set to the previous duty value in 327, and ΔN<-NR (that is, when N is No.
), the duty value Dt is set in S28 to a value obtained by subtracting a predetermined integral constant ■ from the previous duty value, and then idle control is performed using the duty value Dt set as above as a control variable. The near solenoid of the valve 18 is driven (S29), and then the process moves to S13.

As a modification of the routine shown in FIG.
Load correction intake air amount Q read from the memory map of B and corresponding to external loads such as air conditioners.

is calculated, and the feed pack intake air amount Qfb corresponding to the deviation ΔN is calculated using the formula Qtb=Kt
A duty value Dt corresponding to +Qtb may be set.

FIG. 6 shows the routine of ignition timing feedback control. When this control is started, the crank angle signal C8 is read and used to calculate the engine speed N0 (S40), and the airflow The intake air amount signal is read from the meter 14 and is used to calculate the average intake air amount Q for one stroke (S41), and the filling efficiency C is calculated.
8 is calculated using the formula C=K −Q, /N (S42)
.

However, K is a predetermined constant.

Next, from the memory map shown in FIG. 8 stored in the ROM 28, the basic ignition timing θ5 is determined to be the engine rotation speed N. and the filling efficiency C8 (S43).

Next, it is determined whether the flag F is set (
S44), when No, that is, when ignition timing feedback control is not executed, ignition timing θ8g is θ, 9=θ1
(S45), and when Yes, that is, when executing the ignition timing feedback control, the ignition timing θi
9 is calculated using the formula of θ, 9 - θ, +K・ΔN (where K1 is a predetermined constant) (S46), and then a command signal (I GTS) of the ignition timing of 0.9 set as above is generated. is output to the ignition device 19 (S47), and then the process moves to S14. In addition, a signal (IG
W) is determined by executing another ignition control program routine and is output to the ignition device 19.

Note that the fuel injection control in S14 is not directly related to the present application, so a description thereof will be omitted.

Here, the operation of the idle speed control device described above will be explained with reference to FIG. 9.

When the running state is switched to the idling state, the engine speed N0 gradually decreases. And K8 is N0
When entering the range of ±KNI, intake air amount feedback control is substantially started, and the intake air amount supplied from the idle control valve 18 is corrected to the decreasing side. 1ΔN1≧KNE
During this period, ignition timing feedback control is not executed, and only intake air amount feedback control with low responsiveness is executed, so the dead band NR is wide to prevent hunting.
is set to

ΔN further decreases to 1ΔNl<KN! Then, the ignition timing feedbank control is also substantially started, and the ignition timing is largely corrected to the retard side in accordance with ΔN. Since this ignition timing feedback control has high responsiveness, hunting is less likely to occur after the ignition timing feedback control starts. Therefore, while the ignition timing feedback control is being executed, the dead zone NR of the intake air amount feedback control is changed to a narrow dead zone NR2.

Therefore, intake air amount feedback control continues to be performed.
wE is continued until 1ΔN l =NR.

In this way, the dead band NR is changed to be narrower and the intake air amount feedbank control is continued, so the burden of the ignition timing feedback control is reduced accordingly, and the feedback amount of the ignition timing feedback control is reduced in accordance with the intake air amount increase correction. . When ΔN enters the range of the dead band NR2, the feed bank control of the intake air amount is substantially stopped, and only the ignition timing feed bank control reaches ΔN=O, or the ignition timing feedback control enters an extremely narrow dead band. will continue until

In the case of the conventional device, the dead band NR of the intake air amount feedback control was always set to a predetermined wide range, so the feedback control remained in a fixed state with a large deviation ΔN as shown by the two-dot chain line, and the ignition timing also increased. It was not uncommon for the engine to become fixed in a retarded (or advanced) state.

According to the device of this embodiment, while the above-mentioned ignition timing feedback control is being executed, the high responsiveness of the ignition timing feedback control can be effectively utilized by simple control of changing the dead zone NR to the narrow dead zone NRz. Mainly due to intake air amount feedback control, the engine rotation speed N becomes the target idle rotation speed N. Feedback control is performed so that the amount of feedback for ignition timing control is reduced, improving idling stability and preventing deterioration of fuel efficiency during idling.

In the above embodiment, the ignition timing feedback control is substantially started when the deviation ΔN becomes 1ΔNl<KN, but instead of this, the intake air amount feedback control is substantially started. The ignition timing feedback control may be substantially started after a predetermined period of time has elapsed from You may start it.

Note that the bypass passage 17 and the idle control valve 18 are omitted,
The present invention can be similarly applied to a system in which the throttle valve 15 is precisely controlled by a linear solenoid actuator at least in the idle state, and the intake air amount is feedback-controlled via the throttle valve 15.

[Brief explanation of drawings]

Among the drawings, FIGS. 1 to 9 show embodiments of the present invention. FIG. 1 is an overall configuration diagram of an automobile engine and its idle speed control device, and FIG. 2 is an illustration of the idle speed control device. The overall configuration of the control system, Figure 3 is a functional block diagram of idle speed control, Figure 4 is a flowchart of the ignition timing control routine, Figure 5 is a flowchart of the intake air amount feedback control routine, and Figure 6 is the ignition timing control routine. A flowchart of the timing feedback control routine; FIG. 7 is a diagram showing the relationship between cooling water temperature and target idle speed; FIG.
The figure is a diagram showing a map of basic ignition timing with charging efficiency and engine speed as parameters. FIG. 10 is a diagram showing the relationship between ignition timing and torque according to the prior art. E...Engine, 11...Control unit,
14...Air flow meter, 18...Idle control valve, 19...Ignition device, 2o...Distributor. Patent applicant: Mazda Motor Corporation Figure 3 Figure 5 Figure 6 Figure 10 U MII?

Claims (1)

[Claims] (1) An ignition timing adjustment means for adjusting the ignition timing, an intake air amount adjustment means for adjusting the intake air amount, a rotation speed detection means for detecting the actual rotation speed of the engine, and an output from the rotation speed detection means. Ignition timing control means and intake air amount control means that perform feedback control of the ignition timing adjustment means and the intake air amount adjustment means, respectively, so that the actual rotation speed becomes the target idle rotation speed based on the deviation between the actual rotation speed and the target idle rotation speed. An engine idle speed control device comprising: dead band setting means for setting a dead zone of a predetermined width with respect to a target idle speed for intake air amount feedback control by the intake air amount control means; and an output from the ignition timing control means. Based on this, an engine idle speed control device comprising dead zone changing means for instructing dead zone setting means to narrow the dead zone during execution of feedback control of ignition timing.