JPH076472B2 - Engine ignition timing control method - Google Patents

Description

The present invention relates to an ignition control method for stabilizing an engine speed (hereinafter, idle speed) during idling.

[Conventional technology]

In general, the engine speed fluctuates regularly or irregularly when an electric load such as a lighting system or a wiper is applied during idling of the engine, or when the fuel supplied during idling fluctuates.

If the engine speed during idling of the engine is low, such engine speed fluctuation causes engine stall when the engine speed drops, so it is necessary to set the engine speed during idling high.
It was a problem in improving fuel efficiency.

In order to solve this problem, a method is known in which the target idle speed NF is set in advance and the ignition timing is controlled based on the deviation value between the actual idle speed NE and the target idle speed NF ( JP-A-58-176470).

This control method uses the characteristics that, when the engine is unloaded, the engine speed increases when the ignition timing is advanced with an equal throttle opening and an equal air-fuel ratio, and the engine speed decreases when the ignition timing is delayed. In that configuration, the actual idle speed is obtained, and the actual idle speed is compared with a preset target idle speed,
When the actual idle speed is higher than the target idle speed, the ignition timing advance amount at the time of engine idling is reduced, and when the actual idle speed is lower than the target idle speed, the ignition timing advance amount is increased. It is a thing. As a result, the ignition advance is controlled to correspond to the target idle speed, and the idle speed is controlled to the target speed.

However, according to this control method, as shown in FIG. 13 (b), according to the comparative deviation between the target idle speed NF and the actual idle speed NE as shown by the solid line in FIG. 13 (a), Since the idle speed is controlled by controlling the ignition timing, when the amount of air during idling is large, the actual idle speed becomes higher than the target idle speed, the ignition timing is delayed, and the fuel consumption becomes poor. . On the other hand, when the air amount during idling is small, the actual idle speed NE is equal to the target idle speed NF as shown in FIG. 13 (c).
As the ignition timing is further lowered, the ignition timing is advanced, and as a result, the idling is further controlled at the low idle speed, which originally lacks stability, to shift the idling to the unstable side. When the lead angle is excessively advanced, misfire is generated as in the MF shown in FIG. 13 (e), and the fluctuation of the rotational speed becomes large. Therefore, even if the ignition timing is controlled, the effect of stabilizing the idle speed may be almost lost.

On the other hand, recently, in order to stabilize the engine speed during idling, a detour to bypass the throttle valve can be explained, and an idle speed control (ISC) valve is attached to this detour to fully close the throttle valve. And when the vehicle is stopped or at a very low speed (for example, 0 to
By controlling the opening of the ISC valve when idling at 2 km / h), the amount of air flowing through the bypass is controlled to set the engine speed to the target speed (NF ≒ ▲ ▼ (for example, 670 to 730rp
(within the range of m).

When this ISC valve control and the above-mentioned conventional ignition timing control are used together, the deviation between the actual idle speed NE and the target idle speed NF becomes relatively small as shown in FIGS. 13 (c) and 13 (d). As mentioned earlier, the fuel consumption is extremely bad (however, the idle speed is extremely stable) or the idle speed is extremely unstable (the fuel consumption is poor) as mentioned above. Can be prevented.

[Problems to be solved by the invention]

As described above, when the ISC control and the conventional ignition timing control are used together, the fluctuation of the fuel consumption and the fluctuation of the idle speed can be suppressed, but they still become a problem within the tolerance.

Therefore, the present invention, when the engine is idling,
An object of the present invention is to provide an engine speed control method capable of always stabilizing the idle speed and preventing a significant deterioration in fuel consumption.

[Means for solving problems]

In order to solve the above problems, the present invention starts calculation of the average value of the actual engine speed when the actual engine speed during idling reaches a target engine speed range during idling of the engine. The average value up to the present is calculated, and the actual engine speed during idling reaches the target engine speed range during idling based on the deviation value obtained by comparing the average value with the actual engine speed. It is characterized in that the ignition timing is controlled only when the ignition is performed.

[Action]

According to the above configuration, by starting the control by the ignition timing only when the actual engine speed reaches the stable region, the correction amount of the ignition timing becomes an appropriate value, and the stability of the idling speed is secured. You can

Further, since the error in the average value of the engine speed up to the present time is reduced, the control accuracy is improved and a great deterioration in fuel consumption can be prevented.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings. In the embodiments described below, an example in which the present invention is applied to an engine equipped with an ISC valve control device will be described.
It can also be applied to advance control of ignition timing based on the correlation between the target idle speed and the actual idle speed described above, which does not involve ISC control.

First, ISC valve control will be described first, and then advance angle control according to the present invention will be described.

-Engine- Fig. 2 shows an example of an internal combustion engine (engine) equipped with an ISC valve control device. This engine is equipped with an air flow meter 2 for detecting the amount of intake air on the downstream side of an air cleaner (not shown). The air flow meter 2 includes a compensation plate rotatably provided in the damping chamber, a medializing plate connected to the compensating plate, and a potentiometer 4 for detecting the opening of the medializing plate. There is. Therefore, the intake air amount is obtained as a voltage value from the intake air amount signal output from the potentiometer 4. An intake air temperature sensor 6 that detects the intake air temperature and outputs an intake air temperature signal is provided near the air flow meter 2.

A throttle valve 8 is arranged downstream of the air flow meter 2, and an idle switch 10 which is turned on when the throttle valve 8 is fully closed (idle position) is attached to the throttle valve 8, and a surge tank 12 is provided downstream of the throttle valve 8. Is provided. In addition, the surge tank 12 bypassing the throttle valve 8 and located on the upstream side of the throttle valve and on the downstream side of the throttle valve 12
A detour 14 is provided so as to communicate with and. An ISC valve 16A whose opening is controlled by a pulse motor 16 having a 4-pole stator is attached to the bypass 14.
The surge tank 12 communicates with the combustion chamber of the engine 20 via the intake manifold 18 and the intake port 22. A fuel injection valve 24 is attached to each cylinder so as to project into the intake manifold 18.

The combustion chamber of the engine 20 is connected via an exhaust port 26 and an exhaust manifold 28 to a catalytic converter (not shown) filled with a three-way catalyst. An O ₂ sensor 30 that detects the residual oxygen concentration in the exhaust gas and outputs an air-fuel ratio signal is attached to the exhaust manifold 28. An engine cooling water temperature sensor 34 is attached to the engine block 32 so as to penetrate the block 32 and project into the water jacket. This cooling water temperature sensor 34
Detects the engine cooling water temperature and outputs a water temperature signal.

A spark plug 38 is attached to each cylinder so as to penetrate the cylinder head 36 of the engine 20 and project into the combustion chamber. The ignition plug 38 is connected via a distributor 40 and an igniter 42 to an electronic control circuit 44 composed of a microcomputer or the like. Inside the distributor 40, a cylinder discriminating sensor 46 and a crank angle sensor 48, which are variously constituted by a signal rotor fixed to the distributor shaft and a pick-up fixed to the distributor housing, are mounted. In the case of a 6-cylinder engine, the cylinder discrimination sensor 46 is, for example,
Cylinder discrimination signal is output every 720 ° CA and crank angle sensor 4
For example, 8 outputs an engine speed signal every 30 ° CA.
Reference numeral 56 is a vehicle speed sensor that is composed of a magnet fixed to the speedometer cable, a lead switch, and a magnetic sensitive element, and outputs a vehicle speed signal according to the rotation of the speedometer cable.

-Electronic control circuit-Fig. 3 shows an electronic control circuit for controlling the above engine.
The structure of 44 is shown. The electronic control circuit 44 includes a central processing unit (CP
U) 60, read only memory (ROM) 62, random
Access memory (RAM) 64, backup memory (Bu-R)
AM) 66, an input / output port 68, an analog digital converter (ADC) 70, and a bus such as a data bus or a control bus connecting these components. The input / output port 68 has a vehicle speed signal, a cylinder discrimination signal, an engine speed signal, a throttle fully closed signal from the idle switch 10,
The air-fuel ratio signal is input. The input / output port 68 is IS
The ISC valve control signal for controlling the opening of the C valve, the fuel injection signal for opening and closing the fuel injection valve, and the ignition signal for turning the igniter on and off are output to the drive circuit, and the drive circuit responds to these signals. ISC valve, fuel injection valve,
Control each igniter. In addition, the intake air amount signal, intake air temperature signal, and water temperature signal are input to the ADC 70, and the ADC 70
These signals are sequentially converted into digital signals according to the instructions of the CPU. The ROM 62 stores in advance a target rotation speed determined according to the engine cooling water temperature, the intake air temperature, the load state, and the like, and a control program for controlling the pulse motor to control the ISC valve opening.

-Control of ISC valve during idling-Next, a method of controlling the ISC valve during idling will be described. In addition, in order to simplify the description, description will be given below using optimum numerical values, but the present invention is not limited to these numerical values. In this example, when the feedback control condition for idling is satisfied, the engine rotation speed N is controlled to a value within 670 rpm to 730 rpm.

(A) Main routine for calculating the final target number of steps STP Fig. 4 shows the main routine for calculating the final target number of steps STP for controlling the number of steps of the pulse motor that drives the ISC valve and adjusts its opening. Indicates a routine. First, determine whether the engine cooling water temperature is 70 ° C or higher in <Step 100>, determine whether the vehicle speed V is less than 2 km / h in <Step 101>, and stop the vehicle, or in <Step 102>, fully close the throttle valve. It is determined whether or not the feed back control condition is satisfied by determining whether or not the feedback control condition is satisfied. If any one of the judgments in <step 100 to step 102> is negative (when the feed back condition is not satisfied), <> in FIG.
Count value C time incremented by 1 in the interrupt routine every 4 msec shown in steps 120 to 125>
Is set to 0 in <Step 103>, and the value of the learning step number STG is set to the target step number ST in <Step 104>, and then the advance amount control of the ignition timing described later in <Step 115> (Fig. 10). ) Start flag (hereinafter referred to as advance angle control fractal) Fs is reset to "0" and then <
In step 116>, similarly, the start flag (hereinafter, referred to as an average value calculation flag) F _{▲ ▼} of the routine for calculating the average value ▲ ▼ of the actual idle speed in the ignition timing advance amount control, which will be described later, is set to "0". Reset and then proceed to <Step 114>.

On the other hand, when all the determinations in <step 100 to step 102> are affirmative (when the feed back control condition is satisfied), the engine speed N is within 670 rpm to 730 rpm in <step 105> and <step 106>. It is determined whether the value is within the range. Engine speed N is 730r
If pm or more, count value Ctime in <Step 107>
Is 500 or more, that is, whether 2 seconds have elapsed, 2se
When c has elapsed, the target step number ST is decremented by 1 in <Step 108>, the count value C time is set to 0 in <Step 109>, and the process proceeds to <Step 114>.

When the engine speed N is 670 rpm or less, <step
110> It is determined whether or not 2 seconds have passed, and when 2 seconds have passed, the target number of steps ST is incremented by 1 in <Step 111>, <
At step 112>, the count value C time is set to 0, and the operation proceeds to <step 114>.

Further, when the engine speed N is within the range of 670 to 730 rpm, the engine speed N is controlled to the target speed, so that the advance angle control flag Fs is set to "1" in <Step 117>. After setting to "<Step 113>, the target step number ST at this time is set as the learning step number STG B
Store in u-RAM 66, then proceed to <Step 114>.

In step 114, the target step number ST is set as the final target step number STP.

(B) ISC valve opening control routine Next, referring to FIG.
A routine for controlling the opening degree of the C valve will be described. This routine is executed by interruption every 4 msec. As shown in FIG. 7, the stepping motor is provided with N _{1 to} N ₄ pole stators, and the rotor is reversed when the rotor is oriented in the N ₁ pole direction as a reference (1 step). One full clockwise rotation opens the ISC valve for 4 steps.

First, in <Step 130>, the final target number of steps STP
The current step number CPM of the step motor is subtracted from to obtain the difference CRUN. In step 131, it is determined whether the difference CRUN is not 0. If the difference CRUN is 0, the final target step number STP and the current step number CPM match, so the flag F _ISC is set in <step 153>. was reset, <step 154> output n ₁ values of ~n ₄ as all 0 stator n ₁ to n ₄ according to the value of the output n ₁ ~n ₄ in <step 155>
To control. As a result, all of the 4-pole stators are not excited and the rotor is not rotated.

If the difference CRUN is not 0, it is possible to determine which stator the rotor is currently facing, with the remainder, which is obtained by dividing the current step number CPM by 4 of the stator poles in <Step 132>, as a. To do. When the remainder a is 0, that is, when the rotor faces the stator N ₄ , <step 133
> And <Step 134>, the remainder a is set to 4.

In <step 135> follows, the flag F _ISC is determined whether it is excisional, when the flag F _ISC is reset (when the rotor without the stator is excited is stopped), the At step 136, the output na corresponding to the stator in the direction that the rotor is currently facing is set to 1, and at step 137> the flag F _ISC is set and the process proceeds to step 155. As a result, the rotor is once stopped and stabilized in the direction it is currently facing, and when flag F _ISC is set (after the rotor is stabilized in the direction it is currently facing), <step 138>. Difference C
Determine if RUN is negative. If the difference CRUN is positive (ISC valve must be opened), <step 139>
In, the value obtained by adding 1 to the remainder a is set to b, and the stator next to the stator in the direction that the rotor is currently facing is obtained.
Since the stator has four poles, when the value of b exceeds 4, b is set in <step 140> and <step 141>.
The value of is 1. In step 142, it is determined whether or not the output nb of the stator corresponding to b is 1, and if nb = 0, nb = 1 is set in <step 143> and the process proceeds to step 155>. As a result, the rotor faces the direction between the stator corresponding to b and the stator corresponding to b-1, and is rotated by 1/2 step. On the other hand, when nb = 1, b-1 in <step 144>
The output na of the stator corresponding to (= a) is set to 0, the current step number CPM is incremented by 1 in <step 145>, and then the process proceeds to <step 155>. As a result, the rotor is rotated an additional 1/2 step.

The case of controlling the step motor in the opening direction of the ISC valve as described above will be described in more detail with reference to FIG. First, it is assumed that the rotor faces the direction of the stator N ₁ with all the 4-pole stators demagnetized. When the stator N ₁ is excited, the rotor does not rotate, but the stators N ₁ , N
_{When 2} is excited, the rotor faces the direction between stator N ₁ and stator N _2, and when demagnetizing stator N ₁ and exciting stator N ₂ , the rotor faces the direction of stator N _2. . Furthermore, when energizing the stator N ₃ while exciting the stator N _2, the orientation direction between the stator N ₂ and stator N ₃ to the rotor, and demagnetize the stator N ₂ stator
When N ₃ is excited, the rotor faces the stator N ₃ . This causes the rotor to rotate two steps in the direction that opens the ISC valve.

On the other hand, when the difference CRUN is negative (when the ISC valve must be closed), the remainder a to 1 in <Step 146>.
With the subtracted value as b, the stator next to the stator in the direction the rotor is currently facing is determined. And <step 14
In 7>, it is determined whether or not the value of b is 0 or less. If it is 0 or less, the value of b is set to 4 in <step 148>. <Step 1
At 49>, it is determined whether or not the output nb of the stator corresponding to b is 1, and if nb = 0, then at <Step 150>, nb = 1 is set and <
If nb = 1, the output na of the stator corresponding to b + 1 (= a) is set to 0 in <step 151>, and the current step number CPM is decreased by 1 in <step 152>. Then proceed to <Step 155>. This allows
The rotor is rotated to close the ISC valve.

Here, the step number STUP is set to 0 according to the routine of FIG.
It is decremented by 1 every 5 seconds, and the ISC valve is opened / closed by 1 step every 8 msec by the routine of FIG.
When the SC valve is opened by 6 steps, it is opened at a rate of 1 step every 8 msec, that is, 125 steps / sec, and when the ISC valve is closed, it is closed at a rate of 1 step every 0.5 seconds, that is, 2 steps / sec.

In this way, the ISC valve control controls the opening degree of the ISC valve provided in the bypass circuit that bypasses the throttle valve and communicates the upstream side of the slotter valve and the downstream side of the slotter valve when idling. The feedback control is performed so that the target rotation speed becomes the target rotation speed. When the vehicle speed is equal to or higher than a predetermined value, that is, in the high vehicle speed range where the engine is easily stopped when the clutch is cut off, the feedback control is stopped and the predetermined opening ISC valve is opened from the opening during the feedback control to flow to the bypass. The amount of air is increased to prevent engine stop. When the vehicle speed becomes a predetermined value smaller than the predetermined value or less, that is, in a low vehicle speed range where the engine speed does not decrease much even if the clutch is cut, the required opening is left and the opening is more than half the predetermined opening. By reducing the engine speed when the clutch is closed by closing the ISC valve, fuel efficiency is improved and engine braking effect is improved. Then, when the vehicle stops, the constant opening ISC valve is closed to start the feed back control.

—Ignition Timing Control During Idling— First, an outline of ignition timing control during idling according to the present invention will be described. This control method, as shown in FIG. 1, has a target engine speed NE set to the target engine speed NE (for example, 6
70 to 730 rpm, 670 to 7 for simple comparison control
Ignition timing control, which will be described later, is started at a time point (hereinafter referred to as a start time point) Ts when approaching to 700 rpm which is the middle of 30 rpm. The control up to the start point Ts is performed by the ISC valve control, and the control is stopped when the target rotation speed is reached. When the starting point Ts is reached, the actual idle speed NE at that time is set to an initial target value (hereinafter referred to as an initial value) ▲ ▼ _1, and
While comparing the initial value ( ₁₎ and the actual idle speed NE, the ignition timing control is started so that the deviation becomes zero. On the other hand, as soon as the starting point Ts is reached, the actual idle speed
The calculation of the average value ▲ ▼ n up to the current control point of the NE is started, and thereafter the average value ▲ ▼ n at each time point becomes the target value, and this average value ▲ ▼ n and the actual idle speed NE Ignition timing control is performed so that the comparative deviation of is zero. For controlling the ignition timing by comparison, for example, as shown in FIG. 8, a control range of ± 100 rpm of the target sea number is provided, and this ± 100 r
Deviations exceeding pm are ± 10 with respect to the standard advance angle θ _BSE
As shown in Fig. 9, the first method to keep the CA constant (crank angle) is constant, and as shown in Fig. 9, the control width of ± 100 rpm is allowed to have a margin of 20 rpm, and when it exceeds ± 120 rpm, the ignition timing control is stopped. The second method is conceivable. Hereinafter, the first method and the second method will be described separately.

A. First method (see FIGS. 8 and 10) (a) Initial set and various calculations In FIG. 10, first, so-called initial set is performed at the initial stage of control <step 200>. Next, the fuel flow rate Q and the engine speed NE are taken in, and Q / NE is calculated <step 201>. Next, the step number STP of the step motor that determines the opening degree of the ISC valve is calculated <step 202>. This step number STP calculation is the fourth
The "(A) main routine for calculating the final target step number" shown in the figure is used. Next, the fuel injection time T
Is calculated <step 203>. This fuel injection time T
Is for example However, k is calculated by the correction coefficient.

(B) Ignition Timing Calculation Routine (204) After performing the above <Steps 200 to 203>, the ignition timing calculation routine 204 is executed. The ignition timing calculation routine 204 is as follows. First, at <Step 205>, it is determined whether or not the idle switch is “OFF”. If the idle switch is OFF, the process flow in the normal operation state proceeds to <Step 206>, where the idle switch ≠ O.
If FF, processing flow for idle operation <step 20
Go to 7>.

In normal operation (idle switch = OFF), the reference angle θ _{BSE is calculated} from the data of Q / NE and NE in <Step 206>.
To calculate. This calculation formula is stored in advance in the map of the RAM 64. Next, in <208>, the advance angle θ _ISC during ISC control is set to 0 °. The <step 209> seek execution spark advance theta _IG, the following run spark advance theta _IG in accordance with the return connexion retarding amount Q and the engine rotational speed NE <step 202>
To control.

On the other hand, in the idle operation state (idle switch ≠ OFF), in <Step 207>, the average ignition timing advance angle θ _BTDC during idling is set to the reference ignition timing advance angle θ _BSE . The average ignition timing advance angle θ _BTDC is determined depending on the type and capacity of the engine, is a value that can be known empirically and experimentally, and is stored in the map of the RAM64. here,
For example, 15 ° _BTDC .

Next, in <Step 211>, it is confirmed whether or not the advance angle control flag Fs is set to "1". If Fs = 0, the process shifts to the normal operation flow described above, and if Fs = 1, For example, this means that the actual engine speed NE has reached the target value range, which corresponds to the starting point Ts in FIG.
Then, the routine proceeds to 2> to execute the average idle speed NE calculation routine 212 of the actual idle speed NE. Details of this {circle around (n)} calculation routine 212 will be described later with reference to FIGS. 11 and 12. ▲
▼ When the processing of the n calculation routine 212 is completed, the advance angle θ _ISC is calculated by the ISC control advance angle θ _ISC calculation routine 213 in <step 213>, and the calculated value is used for the calculation of <step 209>. . In the same manner, the process is repeated by returning to <step 201>.

(C) ▲ ▼ n Calculation Routine (214) Here, the ▼▼ n calculation routine 214 will be described. Referring to FIG. 11, it is judged in <step 300> whether the average value calculation flag F _{▲ ▼} is set to "1". If F _{▲ ▼} = 0, <step 301>
If F _{▲ ▼} = 1 then go to the average value calculation flow <
Go to step 302>.

When F _{▲ ▼} = 0, it is determined in <step 301> whether the actual idle speed NE is 730 rpm or less. NE> 730r
Since pm means that the engine is not in the idling state, the ISC advance angle θ _{ISC is set} to 0 ° in <Step 303>, and the ▲ ▼ n calculation routine 214 ends. In the case of NE ≦ 730 rpm, it means that the rotation speed has approached the target rotation speed by the feedback control, and the actual idle rotation speed NE at this time is initially set as the actual idle rotation speed average value ▲ ▼ ₁ in <Step 304>. To do. This initial value ( ₁₎ is the target value at this point. Next, in step 305, the average value calculation flag F _{▲ ▼ is set} to "1", and the ISC control advance angle θ _ISC calculation routine 213
Proceed to <Step 306>.

(D) ISC control advance θ _ISC calculation routine (213) In <Step 306>, the deviation between the initial value ▲ ▼ ₁ and the current actual idle speed NE is 100 rpm based on the initial value set in <Step 304>. It is determined whether or not the above. When the low side deviation (▲ ▼ _1- NE) ≧ 100 rpm,
The current actual idle speed NE is 10 than the initial value ▲ ▼ ₁
Since it is 0 rpm or more lower, the ISC advance angle θ _ISC is advanced by 10 ° in <Step 307> to increase the rotational speed. Low deviation (▲ ▼ _1- NE) <100 rpm <step
At 308>, it is determined whether or not the high-side deviation (NE- ▲ ▼ ₁ ) ≧ 100 rpm, that is, the deviation between the current actual idle speed NE and the initial value ▲ ▼ ₁ exceeds 100 rpm. When the speed is 100 rpm or more, the ISC advance angle θ _ISC is delayed by 10 ° by <Step 309> to reduce the rotation speed. High side deviation (NE- ▲
▼ ₁ ) When <100 rpm, interpolation calculation is performed in <step 310>, the calculated value is set as the ISC advance angle θ _ISC , and the routine 204 is ended.

On the other hand, in <Step 300>, the average value calculation flag F
_If it is determined that _{▲ ▼} = 1, then <
In step 302>, it is determined whether the count value Ctime is larger than "25". If C time ≥25, proceed to <step 311>. If C time <25, jump to <steps 311 and 312> and proceed to <step 306>. In addition,
C time = 25 means that the count value C time is incremented by 1 every 4 msec, so 100 msec
This means that this processing flow is executed every time. If C time ≥25, the count value C time is reset to 0 at the next <Step 311>, and the counter restarts counting operation again. Next, <Step 312
>, The average value ▲ ▼ n of the actual idle speed is obtained. A weighted average is used to calculate the average value ▲ ▼ n. This average value ▲ ▼ n is used in <Step 306>,
Instead of the previously set initial value {circle around ( ₁₎ }, the advance control is performed by the θ _ISC calculation routine 213 with this average value {circle around (n)} as a target value.

B. Second Method (See FIGS. 9 and 12) The difference between the second method and the first method is that, as shown in FIG. 12, an ISC control advance angle θ _ISC calculation routine 213 <Step 314> is inserted between <Step 306> and <Step 307>, and <Step 313> is inserted between <Step 306> and <Step 308>, and <Step 315>. > Is added. Since other steps are the same as those in the first method, the same reference numerals are given and the description thereof will be omitted.

At <Step 306>, low side deviation (▲ ▼ n (or ▲
▼ ₁ ) -NE) ≧ 100 rpm <Step 314>
To the lower side deviation (▲ ▼ n (▲ ▼ ₁ )-
NE) ≦ 120 rpm is judged. Low side deviation (▲ ▼ n
If −NE) is less than 120 rpm, the advance angle is uniformly advanced by + 10 ° and set to θ _ISC . As a result, the idle speed N
E rises. If the low-side deviation (▲ ▼ n-NE) is greater than 120 rpm, it will exceed the control range during idling. Therefore, at <Step 315>, the ISC control advance angle θ _{ISC is set} to 0 ° and this control flow is executed. (That is, the ignition timing control is stopped).

Low side deviation (▲ ▼ n-NE) <100 at <Step 306>
In the case of rpm, proceed to <Step 313>, and set the high side deviation (NE-
It is determined whether or not n) is greater than 120 rpm.
If the high side deviation (NE- ▲ ▼ n) is larger than 120npm, it means that the control range during idling is exceeded.
Control proceeds to step 315> and control is stopped. On the other hand, if the high-side deviation (NE- ▲ ▼ n) is smaller than 120 rpm and larger than 100 rpm (100 <NE- ▲ ▼ n> 120), _θISC is uniformly delayed by -10 ° in <Step 309>. And the control ends. If the high side deviation (NE- ▲ ▼ n) is smaller than 100 rpm in <Step 315>, interpolation calculation is performed in <Step 310>, and the calculated value is θ.
Set to _ISC and end control.

As described above, according to the present invention, the average value ▲ ▼ n of the actual engine speed NE is controlled as the target value as shown by the broken line in FIG. The reference advance angle θ _BSE does not greatly deviate, and I
Fig. 13 (c) also shows when the SC valve controller is used together.
As shown in (d), it is possible to perform control with less variation. After all, as shown in FIGS. 13 (e) and 13 (f), a large fluctuation can be suppressed as in the conventional case.

〔The invention's effect〕

As described above, according to the present invention, it is possible to constantly stabilize the idling speed and prevent a significant deterioration in fuel consumption when the engine is idling.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the concept of ignition timing control according to the present invention, FIG. 2 is a diagram showing a schematic configuration of an engine equipped with an ISC valve control device, and FIG. 3 is a block diagram showing an electronic control circuit. The figure shows the flow chart of the step number calculation routine for the step motor of the ISC valve, Fig. 5 shows the flow chart of the interrupt routine, Fig. 6 shows the flow control routine of the ISC valve opening control routine, and Fig. 7 shows the step motor control. FIG. 8 is an explanatory view showing a first method in an embodiment of the present invention, and FIG. 9 is a flow chart showing the same.
10 is a flow chart showing a schematic flow of an embodiment of the present invention, FIG. 11 is a flow chart showing an ignition timing calculation routine in the first method, and FIG. 12 is a second method. FIG. 13 is a waveform chart showing the ignition timing calculation routine of FIG. ▲ ▼ ₁ …… Initial value ▲ ▼ n …… Average value 204 …… Ignition timing calculation routine 212 …… ▲ ▼ n calculation routine 213 …… θ _ISC calculation routine

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Suematsu 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) Reference JP-A-58-131362 (JP, A)

Claims (1)

[Claims] 1. When the actual engine speed during idling reaches a target engine speed range during idling of the engine, calculation of the average value of the actual engine speed is started and the average value up to the present is calculated. Obtained, based on the deviation value obtained by comparing the average value and the actual engine speed, the ignition timing only when the actual engine speed during idling reaches the target engine speed range during idling An ignition timing control method for an engine, characterized by controlling the engine.