JPH01253547A - Engine idling speed controller - Google Patents

Abstract

PURPOSE:To improve the fuel consumption performance in idling an engine by advancing the ignition timing controlled by an ignition timing control means when the engine is cold and by limiting intake air flow compensation action by an intake air flow adjusting means. CONSTITUTION:Intake air flow is adjusted by an intake air flow adjusting means A in idling an engine, and also, ignition timing is controlled by an ignition timing control means B to feed-back control engine speed to specified desired engine speed in idling the engine. In addition, fuel to be supplied to the engine is compensated to increase by a fuel loading means C while the engine is cold. In such a device, an ignition timing correction means D is provided, and ignition timing is advanced at a specified angle by the ignition timing correction means D while the engine is cold. This limits intake air flow increase compensation action by the intake air flow adjusting means A.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine idle speed control device that controls the engine idle speed to converge to a predetermined idle speed.

(Prior art) Conventionally, in engine idle speed control, ignition timing and intake air amount are feedback-controlled according to the rotational deviation between the actual engine speed and a predetermined target idle speed, and the idle speed of the engine is controlled. A technique for converging the number of rotations to the target idle rotation speed is known, for example, as seen in Japanese Patent Laid-Open No. 121843/1983.

First, controlling the idle speed by controlling the ignition timing has the advantage of particularly excellent control responsiveness because a change in the ignition timing immediately appears as a fluctuation in engine output.

On the other hand, the control of the idle speed by controlling the amount of intake air is inferior to the control of the ignition timing in terms of control responsiveness, but it can sufficiently respond to large load fluctuations and provides stable speed control. can be done. Therefore, it is an indispensable basic system for controlling the engine speed as described above. Therefore, when external loads of the engine such as the air conditioner compressor, electrical loads (headlights, etc.), power steering oil pumps, etc. operate using this intake air amount control method, it is possible to respond to the operation of these external loads. In order to automatically improve the torque characteristics of the engine output torque, a technique for automatically increasing and correcting the amount of intake air, etc. according to the load amount is also generally employed as is well known.

In an engine idle speed control device that controls the amount of intake air and employs such a load correction system, the transient rotation drop (downshoot) when the external load is turned on and the speed up (overshoot) when the external load is turned off are detected. shoot)
In order to prevent this, a dead zone of a predetermined width is usually set.

That is, the control m of the intake air amount control means during the feedback control of the idle speed is normally based on the idle target speed No. and the engine speed at that time, as shown in FIGS. 6(a) to (c), for example. It is configured as an integral quantity that changes in the positive or negative direction depending on the size of the deviation ±ΔNe (±ΔNe=Ne−No) from the actual rotation speed Ne,
The control center is naturally set based on the idle target rotation speed No. at that time (during the relevant operation), but in general, for rotational fluctuations around the target rotation speed No., hanging is prevented by turning the external load on and off. From the viewpoint of
Orpm level).

The dead zone B of the conventional idle speed control device is always constant regardless of the engine load condition, and the rotation deviation amount ΔNe is within the dead zone set value width B (±50 r
pa+) in either the positive or load direction, the intake air amount is necessarily increased or decreased in accordance with the rotational deviation amount ΔNe. The corrected intake air amount is supplied to the engine through a bypass intake passage for controlling the intake air amount during idling, which is installed to bypass the throttle valve, for example.

Therefore, in the case of the conventional idle speed control device, while the engine speed Ne is fixed at the upper limit Ne+α or the lower limit Ne−α of the dead band width B,
There are cases where the engine rotational speed Ne is stabilized while the ignition timing is significantly retarded or advanced with respect to the original target advance value (control center value).

However, this causes inconveniences such as fluctuations in engine output, deterioration in fuel efficiency, and deterioration in exhaust emissions.

Therefore, when the ignition timing is controlled in conjunction with the control of the intake air m as a countermeasure, when the average value of the ignition timing of the predetermined number of times of control is in a retard state with respect to the target advance value, It is conceivable to gradually reduce the correction amount on the side of the intake air amount control means and perform tailing control so that the reference value of the ignition timing converges to the target advance value.

(Problems to be Solved by the Invention) However, if the above configuration is employed when the engine is cold in the same way as when the engine is warm, the following problem occurs.

In other words, when the engine is cold, unlike when it is warm, the target idle speed itself is high, and of course the amount of fuel is greatly increased from the standpoint of ensuring startability and promoting warm-up. If the engine is retarded in the same manner as when the engine is running, it will result in a significant deterioration in fuel efficiency.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems. ignition timing control means for controlling the ignition timing of the engine; and fuel increasing means for increasing the amount of fuel supplied to the engine when the engine is cold; The engine speed of the engine is feedback-controlled to a predetermined target idle speed by adjusting the amount of intake air supplied to the engine and controlling the ignition timing of the engine by the ignition timing control means, while increasing the amount of fuel. An engine idle speed control device configured to increase the amount of fuel when the engine is cold by means of an ignition timing correction means for correcting the ignition timing controlled by the ignition timing control means; , the ignition timing correction means advances the ignition timing controlled by the ignition timing control means by a predetermined angle, thereby limiting the intake air amount increase correction operation by the intake air amount adjustment means. .

(Function) In the problem-solving means of the present invention described in item 2, both the ignition timing control means and the intake air amount adjustment means are provided, and since the engine speed is controlled by their cooperation, the ignition timing is controlled. Ensuring high response through control means and intake air fi
[) It is possible to control the idle speed with high precision and stability while ensuring responsiveness to load fluctuations by the J adjusting means.

At the same time, the fuel increasing means and the ignition timing h
n thousand means are provided, and when the engine is cold, sufficient fuel is increased and stable starting performance is achieved.
The ignition timing correction means corrects the original ignition timing control value by the ignition timing control means in a predetermined advance direction, thereby improving engine output and making it possible to substantially reduce the amount of intake air. control.

As a result, the control amount on the intake air amount adjusting means side naturally becomes smaller, and the controlled fuel injection amount correspondingly decreases as well.

(Example) First, FIGS. 2 and 3 show an idle speed control device for an automobile gasoline engine in which the present invention is applied, and FIG. FIG. 3, which is a schematic diagram of the control system, is a flowchart showing the idle rotation speed control operation of the engine control unit in the control system.

First, the outline of the control system according to the embodiment of the present invention will be explained with reference to FIG. 2, and then the control of the main parts will be explained.

In FIG. 2, reference numeral l is the engine body, and intake air is taken in from the outside via an air cleaner 30.
Thereafter, the air is supplied to each cylinder via an air flow meter 2 and a throttle chamber 3.

Further, fuel is supplied from the fuel tank 12 to the engine side by the fuel pump 13 and injected by the fuel injector 5. And a special accelerator pedal for vehicle driving! The intake air into the cylinder during L/operation is controlled by a throttle valve 6 provided in the throttle chamber 3. The throttle valve is operated in conjunction with the accelerator pedal, and is maintained at a minimum opening degree during idle operation. and,
In the minimum (fully closed) opening state, the idle switch ID-
5W turns on.

The throttle chamber 3 is provided with a bypass intake passage 7 that bypasses the throttle valve 6, and the bypass intake passage 7 includes an intake air mR adjustment means for controlling the engine rotational speed during idling. A current-controlled solenoid valve (ISO valve) 8 is provided. Therefore,
In the idle operating state, the intake air that has passed through the air flow meter 2 is supplied to each cylinder via the bypass intake passage 7, and the amount of intake air supplied is adjusted by the solenoid valve 8. The opening/closing state of the solenoid valve 8 (valve opening degree) is controlled by a solenoid valve control signal supplied from an engine control unit (hereinafter abbreviated as ECU) 9 according to a duty ratio.

That is, in the case of the above-mentioned idle state, an ECU constituted by a microcomputer as described later is used to constitute an electronic intake air amount control means, and the solenoid valve 8, which is the above-mentioned intake air amount adjustment means, is adjusted to a predetermined value. If the actual rotation speed Ne obtained by the predetermined basic control amount set corresponding to the idle target rotation speed NO does not match the set idle target rotation speed No. A configuration is adopted in which the actual rotational speed Ne is converged to the set idle target rotational speed NO by correcting the predetermined basic control amount according to the deviation amount ΔNe and the load amount EL.

The final solenoid valve control m (final control amount) including the above correction amount is generally determined as follows.

Final control amount G = CB + ΣGL + GFB (1) However, GB2 basic control amount GL: load correction amount corresponding to various engine loads GFB: feedback correction amount based on rotational deviation Here, the above basic control mGn is generally It is set in correspondence with the engine rotation speed and the cooling water temperature value based on characteristic values specific to the engine at the time of no load and no deterioration. Further, the load correction 1iGL corresponding to the engine load (for example, air conditioner, power steering, etc.) is determined as a unique value corresponding to the respective load fflELL, and acts as an intake air amount increase value. Further, the feedback correction ff1GFB is a correction amount during closed-loop control that is determined depending on the driving state and the amount of deviation between the actual engine speed and the target engine speed.

That is, as is clear from the above general formula (which is a formula for calculating the duty ratio of the control signal that drives and controls the solenoid of the solenoid valve 8, which is the above-mentioned intake air amount adjusting means), the final control ff1G Centering around the basic control amount GB determined by the unique characteristic value and the cooling water temperature, a correction amount GL corresponding to the load amount and a feedback correction IGFB corresponding to the rotation speed deviation amount are added.

The control amount of the intake air amount control means during the feedback control described above is, for example, as shown in FIG.
) to (c), it is configured as an integral quantity that changes in the positive or negative direction depending on the magnitude of the deviation ±ΔNe (±ΔNe=Ne−No) between the target rotation speed No and the actual rotation speed Ne. The center of control is naturally set based on the target rotation speed No. at that time (at the time of the relevant operation), but generally speaking, for rotational fluctuations around the target rotation speed No., the control center is set as shown in the figure from the viewpoint of preventing hunting, etc. A dead zone (non-operating area) B having a predetermined width is set as follows (normally B=about ±5 Orpm).

This dead zone B is always constant regardless of the engine load condition, and the rotational deviation mΔNe is the dead zone setting value B (±
5 Orpm), the intake air amount must be corrected to increase or decrease in accordance with the rotational deviation amount ΔNe. The increased/decreased intake air amount is then supplied to the engine through the bypass intake passage 7.

Further, reference numeral 10 indicates an exhaust pipe provided with, for example, a three-way catalytic converter 11.

On the other hand, sign! Reference numeral 4 denotes a spark plug provided in the cylinder head of the engine main body l, and the spark plug 14
A predetermined ignition voltage is applied to the EC via the distributor 17 and the igniter 18, and the application timing of this ignition voltage, that is, the ignition timing is determined by the above-mentioned EC.
It is controlled by the ignition timing control signal Igt supplied from U9 to the igniter 18. Also, code 1
Reference numeral 9 denotes a knock sensor provided in the cylinder block portion of the engine main body 1, which outputs a voltage output Vo corresponding to the intensity of occurrence of knocking in the engine, and inputs it to the ECU 9. Further, reference numeral 2o denotes a boost pressure sensor 20, which detects an engine boost pressure B corresponding to the engine load and inputs it to the ECU 9. Further, reference numeral 21 is a load detection means for detecting the application of an external load (air conditioner, power steering device, etc.) to the engine.
The N state is detected and the detection signal is input to the same ECU 9.

The ECU 9 is configured, for example, with a microcomputer (CI'U) serving as a calculation unit at its core, and includes a control circuit for intake air amount, ignition timing, etc., memory (ROM and RAM), an interface (Ilo) circuit, etc. . In addition to the above-mentioned detection signals, the interface circuit of the ECU 9 includes, for example, an engine start signal (ECU trigger) from a starter switch (not shown), and an engine rotation speed detection signal Ne1 from the engine rotation speed sensor 15.
The engine cooling water temperature detection signal TW detected by the water temperature thermistor 1G, the throttle opening detection signal TVO detected by the throttle opening sensor 4, the intake air amount detection signal Q detected by the air flow meter 2, etc. Various detection signals necessary for engine control are also input.

Next, control of the ignition timing and intake air amount during idling operation by the ECU 9 will be described in detail with reference to the flowchart of FIG. 3.

First, in step Sol, the cooling water temperature value Tw of the engine is read.

Next, proceeding to the second step S, the target advance angle value O6, which is the reference value for ignition timing control, is determined from the ignition timing table of the engine according to the location of the engine cooling water temperature value TW read in step S1. Look up.

Next, the process proceeds to step Ss, and the lookup value θ is determined. (T
V) is added to the previous ignition timing product 'n(flS), and the addition count flag n is incremented by one time (n+1)l for each addition operation.

Then, the process further proceeds to step S4, and the target ignition timing lookup I in step S is performed. 100(
The number of additions n of T v) is the predetermined set number of times 10
0) is reached.

Here, the set number of times n (n=I O) is equal to the control value n (1
0) This is the set number of times for determination to calculate the moving average value between periods.
In the case of S, it indicates that the number of additions n has reached the set number of times 10, in other words, that the addition of the ignition timing control value looked up from the ignition timing table has been completed for 10 times. In the case of , it indicates that the addition is still in progress.

Then, first of all, in the case of YES, the next step S5
Then, the average value S/10 of the ignition timing within the above-mentioned addition period (n cycles) is set to a predetermined target ignition advance angle that is predetermined according to the engine cooling water temperature value T1, as shown in FIG. 4, for example. Value (optimal value) θo(rv) = θ. (s) Determine whether or not the value is greater than or equal to (s).

On the other hand, in the case of No, the above steps S,
Return to and repeat the above operation (S, -) until n=10.
Continue S,).

On the other hand, if the determination in step S is YES, that is, the actual intake air amount to the engine is insufficient to maintain the target idle speed, and the ignition timing is corrected to the advanced side. This indicates that feedback control of the idle speed is being performed to increase the torque, so proceed to step S and calculate the final control amount of equation (1) above, which determines the intake air amount to the engine. After increasing the intake air amount by increasing G by Δg, the process proceeds to step S, and the integrated value (
(memory value) Reset the values of Sl and addition count flag n to 0.

On the other hand, if the determination in step S11 is No, the actual intake air amount is too large, so the ignition timing is controlled to the retard side to reduce the torque, thereby reducing the target idle speed No. This shows that maintenance is being carried out.

Therefore, in this case, if the intake air amount is left at the same control amount, the fuel efficiency will eventually deteriorate considerably.

Therefore, in this case, the process proceeds to step S, where the control f of the above equation (1) determines the intake air amount to the engine.
The value of f1G is corrected to be smaller by a predetermined value Δg to reduce the amount of intake air supplied to the engine, and the amount of supplied fuel is also reduced accordingly. As a result, fuel efficiency is improved compared to the conventional case.

Then, when the operation in step S8 is completed, the integrated value S1 addition count determination flag n in step S is reset in the same manner as in step S7, and the process returns to step S1.

(Effects of the Invention) As approved above, the present invention provides an engine intake air m
The intake air amount adjusting means adjusts the amount of intake air, the ignition timing control means controls the ignition timing of the engine, and the fuel increasing means controls the amount of fuel supplied to the engine when the engine is cold. Feedback control of the engine rotational speed of the engine to a predetermined idle target rotational speed by adjusting the amount of intake air supplied to the engine by the air amount adjustment means and controlling the ignition timing of the engine by the ignition timing control means. On the other hand, in an engine idle speed control device configured to increase the amount of fuel by the fuel increase means when the engine is cold, an ignition timing correction means is provided for correcting the ignition timing controlled by the ignition timing control means, When the engine is cold, the ignition timing correction means advances the ignition timing controlled by the ignition timing control means by a predetermined angle, thereby limiting the intake air amount increase correction operation by the intake air amount adjustment means. It is characterized by the following.

That is, in the configuration of the present invention, both the ignition timing control means and the intake air amount adjustment means are provided, and the engine speed is controlled by their cooperation, so that the ignition timing control means has high responsiveness. It is possible to control the idle rotation speed with high precision and stability while ensuring both the stability of the intake air m and the responsiveness to load fluctuations by means of adjusting the intake air m.

And at the same time, more fuel! 4 means and ignition timing correction means are provided, and when the engine is cold, sufficient fuel is increased and stable starting performance is achieved.
The ignition timing correction means corrects the original ignition timing control value by the ignition timing control means in a predetermined advance direction, thereby improving engine output and making it possible to substantially reduce the amount of intake air. control.

As a result, the control amount on the intake air amount adjusting means side naturally becomes smaller, and the controlled fuel injection amount correspondingly decreases as well.

Therefore, according to the configuration of the present invention, even during cold periods when the amount of fuel supplied is large, the characteristics of the idle frequency control system based on ignition timing control are effectively utilized to effectively compensate for the drawbacks of the intake air amount control method. This makes it possible to both improve fuel efficiency during idling and prevent fluctuations in the amount of intake air.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a system chart showing the overall configuration of an engine idle speed control device according to an embodiment of the present invention, and FIG. A flowchart showing timing and intake air amount control operations, FIG. 4 is a target ignition advance value map used in the control operation of FIG. 3, FIG. 5 is an ignition timing correction amount map, and FIG. 7A to 7C are time charts showing dead zone setting characteristics of an idle rotation speed control system based on intake air amount control. ! ... Engine body 2 ... Air flow meter 5 ... Fuel injector 7 ... Bypass intake passage 8 ... Solenoid valve 9 ... φ ... Engine control unit 14 ...
- Spark plug 15...Engine speed sensor 17...Distributor 18...Igniter 20...Boost pressure sensor 21...Load detection means

Claims (1)

[Claims] 1. Intake air amount adjusting means for adjusting the intake air amount of the engine, ignition timing control means for controlling the ignition timing of the engine, and fuel increasing means for increasing the amount of fuel supplied to the engine when the engine is cold. During idling operation, the intake air amount adjusting means adjusts the amount of intake air supplied to the engine, and the ignition timing controlling means controls the ignition timing of the engine, thereby controlling the engine rotational speed of the engine to a predetermined predetermined value. In an engine idle speed control device, the ignition timing controlled by the ignition timing control means is corrected in an engine idle speed control device which performs feedback control to the idle target speed and increases fuel when the engine is cold using the fuel increase means. An ignition timing correction means is provided, and when the engine is cold, the ignition timing correction means advances the ignition timing controlled by the ignition timing control means by a predetermined angle, thereby adjusting the intake air amount by the intake air amount adjustment means. An engine idle speed control device characterized by limiting an increase correction operation.