JPH0411746B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an idle control device for an internal combustion engine for an automobile.

<Prior art> As a conventional idle control device for an internal combustion engine,
For example, there is one described in Japanese Patent Publication No. 58-57623. An idle control valve is installed in the auxiliary air passage that bypasses the throttle valve, and a control means using a microcomputer controls the opening of the idle control valve to set the engine's idle speed to a target according to the engine cooling water temperature, etc. Feedback control is applied to the idle speed.

<Problems to be Solved by the Invention> Incidentally, in such a conventional idle control device, the following feedback loops are repeated.

Idle rotation speed detection Comparison with target idle rotation speed (deviation calculation) Control output to the idle control valve according to the deviation Idle control valve operation Change in intake air amount Explosive force change (torque change) → Idle rotation speed change Here, ~ can be detected and calculated instantaneously, and the delay in operation is negligible for , but the process of , takes a considerable amount of time.

For this reason, the integration time of the feedback has to be delayed, and there is a problem in that it is not possible to absorb (feedback) even minute fluctuations in idle rotation.

Therefore, in Japanese Patent Application No. 58-229825, the present applicant focused on the fact that the torque can be changed in a responsive manner by advancing or retarding the ignition timing. We have proposed a system that performs feedback control of the idle rotation speed by correcting and controlling the idling speed.

However, in uniform ignition timing correction control for each cylinder according to the deviation from the target idle speed, there is a difference in explosive power between each cylinder due to differences in compression ratio, fuel distribution, intake efficiency, etc. It was not possible to reduce rotational fluctuations and engine vibrations caused by them.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an idle control device using ignition timing correction control that can reduce rotational fluctuations and engine vibrations during idle based on differences in explosive power between cylinders. .

<Means for Solving the Problems> In order to achieve the above object, the present invention, as shown in FIG. and an integral unit that increases or decreases the ignition timing correction value for each cylinder by a predetermined amount in the direction of making the idle rotation speed detected for each cylinder the same as the idle rotation speed of other cylinders. a control means C; and a correction value correction means D that calculates the average value of the ignition timing correction values of all the cylinders and corrects the ignition timing correction value of each cylinder by the same amount in the direction of setting the average value to 0. , an ignition timing correction means E for correcting the ignition timing control value set according to engine operating conditions by adding correction values for each cylinder and outputting the corrected value to the ignition device F.

<Function> In the above configuration, each cylinder has a correction value for correcting the ignition timing, and the actual idle rotation speed during the explosion stroke after ignition is detected for each cylinder,
The idle speed of each cylinder is adjusted in the direction of making it the same as the idle speed of other cylinders (for example, the idle speed of another cylinder detected immediately before, or the average value of the idle speed of all cylinders detected most recently). The ignition timing correction value is increased or decreased by a predetermined amount, the correction value is added to the ignition timing control value at the next ignition, and ignition is performed based on this. In this way, by correcting the ignition timing for each cylinder and making the explosive power of each cylinder the same, it is possible to significantly reduce rotational fluctuations during idling and reduce engine vibration.

In addition, the average value is calculated from the ignition timing correction values set by integral control for each cylinder,
The ignition timing correction value for each cylinder is corrected by the same amount so that the average value becomes 0, and the average value of the correction value group does not deviate from 0, so electrical loads, brakes, etc. Even if there are load fluctuations caused by the engine operating conditions, the correction value group as a whole can be prevented from largely shifting to the plus side or minus side, causing the ignition timing to no longer correspond to the engine operating conditions, and good control can always be performed. I can do it.

<Example> An embodiment of the present invention will be described below.

In FIG. 2, air is taken into the engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4, and an intake manifold 5. As shown in FIG.

An air flow meter 6 is provided in the intake duct 3 and outputs a voltage signal corresponding to the intake air flow rate. The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the flow rate of intake air. An idle switch 8 is attached to the throttle valve 7 to detect its fully closed position. Further, an auxiliary air passage 51 is provided to bypass the throttle valve 7, and an idle control valve 52 is interposed in this auxiliary air passage 51. The opening degree of this idle control valve 52 is controlled by a signal from the same or different unit as the control unit 30, which will be described later. The opening degree is controlled in order to feedback control the speed to the target idle speed. The intake manifold 5 is provided with a fuel injection valve 9 for each cylinder, which is opened by a drive pulse signal from the same or different control unit 30 (described later), and is pressurized by a fuel pump (not shown). Fuel controlled to a predetermined pressure by a regulator is injected and supplied to the engine 1.

Each cylinder of the engine 1 is provided with an ignition plug 10, and a high voltage generated by an ignition coil 11 is sequentially applied to these via a distributor 12, thereby igniting a spark and creating a mixture. ignite and burn. Here, the generation timing of high voltage of the ignition coil 11 is controlled via a power transistor 13 attached thereto. Therefore, the ignition timing is controlled by controlling the on/off timing of the power transistor 13 using an ignition signal from a control unit 30, which will be described later.

A photoelectric crank angle sensor 14 is built into the distributor 12. The photoelectric crank angle sensor 14 is connected to the distributor shaft 15.
Signal disk plate 16 that rotates together with
and a detection section 17. The signal disc plate 16 is formed with 360 slits 18 for position signals (1° signal) and, in the case of a 4-cylinder engine, 4 slits 19 for reference signals (180° signal). One of the reference signal slits 19 is also used to identify the No. 1 cylinder. The detection unit 17 detects these slits 18 and 19 and generates a position signal (360 slits 18 per revolution of the distributor shaft 15).
720 position signals) and a reference signal including a No. 1 cylinder discrimination signal. Here, the engine rotation speed can be calculated by measuring the period of the reference signal. Therefore, the crank angle sensor 14 constitutes a part of the means for determining the ignition cylinder, and also constitutes a part of the means for detecting the engine speed (including the idle speed).

In addition, a neutral switch 22 that detects the neutral position of the transmission, a vehicle speed sensor 23 that outputs a pulse signal with a period corresponding to the vehicle speed, and the like are provided.

Signals from the air flow meter 6, idle switch 8, crank angle sensor 14, neutral switch 22 and vehicle speed sensor 23 are input to a control unit 30.

Control unit 30 is constructed as shown in FIG. 31 is a CPU, 32 is an idle decoder, 33 is a ROM, and 34 is a RAM.

Among the input signals to the CPU 31, the voltage signal from the air flow meter 6 is an analog signal, so the analog input interface 35 and
It is input via the D converter 36. Each on/off signal from the idle switch 8 and the neutral switch 22 is input via a digital input interface 37. Crank angle sensor 14
a position signal and a reference signal from
Pulse signals from the vehicle speed sensor 23 are input via waveform shaping circuits 38 and 39, respectively.

Here, the CPU 31 determines the optimum ignition timing (ignition advance angle ADV) by performing arithmetic processing based on various input signals and data on the ROM 33 and RAM 34 according to the program on the ROM 33,
At that timing, an ignition signal is sent via the driver 40 to the power transistor 13 for driving the ignition coil 11.

In detail, first, the ignition advance angle ADV, which is predetermined according to the engine speed N and the load, is determined.
Search from the map on ROM33. Note that the load is the basic fuel injection amount Tp (=
K・Q/N, K is a constant) is used. Next, the search value of the ignition advance angle ADV is corrected as necessary to determine the final ignition advance angle ADV. When the ignition advance angle ADV is determined, if the reference signal from the crank angle sensor 14 is output at, for example, 80 degrees before compression top dead center, set (80 - ADV) in the counter and input the reference signal. Thereafter, each time a position signal of 1° is input, the count value is subtracted by one, and when the count value reaches 0, an ignition signal is output to the power transistor 13 via the driver 40.

When controlling the ignition timing, the ignition timing is corrected to reduce rotational fluctuations and engine vibrations during idling.

Ignition timing control including idle control is performed according to the flowchart in FIG.

The flowchart shown in FIG. 4 will be explained.
Incidentally, this flow is executed in synchronization with the reference signal from the crank angle sensor 14 during the arithmetic processing period shown in FIG. Further, the following is a case of 4 cylinders, and No. 1 to No. 4 cylinders represent the ignition order.

In step 1 (S1 in the figure), the cycle of the reference signal from the crank angle sensor 14 is calculated to detect the engine rotational speed N, which is determined as its reciprocal.

In step 2, it is determined whether or not it is in an idle state. This idle determination is performed based on signals from the idle switch 8, which is turned on when the throttle valve 7 is in the fully closed position, the neutral switch 22, which is turned on when the transmission is in the neutral position, and the vehicle speed sensor 23, which detects the vehicle speed. Idle switch 8 is on and neutral switch 2
2 is on, and when the idle switch 8 is on and the vehicle speed detected by the vehicle speed sensor 23 is below a predetermined value, it is determined that the vehicle is in an idle state, and the process proceeds to step 3. If the state is not idle, the process advances to step 23.

In step 3, the previous ignition cylinder is determined.
This is performed based on the generation of the No. 1 cylinder discrimination reference signal and the number of subsequent reference signals generated in advance. Here, referring to FIG. 5, if the current time is the calculation processing period _T2 immediately after the reference signal REF2 following the reference signal REF1 for No. 1 cylinder discrimination, the previous ignition cylinder is the No. 1 cylinder. It is determined that This portion, together with the crank angle sensor 16, corresponds to means for determining the ignition cylinder.

Then, based on this determination, the process branches to steps 4 to 7, and N is substituted into the stored values N ₁ to N ₄ of the idle rotation speed corresponding to the ignition cylinder.

That is, as in the above example, when the current calculation processing period is _T2 , it is determined that the previous ignition cylinder is the No. 1 cylinder, and the process proceeds to step 5, where the engine rotation speed N detected in step 1 is determined. is stored as the idle rotation speed N ₁ during the explosion stroke of No. 1 cylinder. This is because N in this case is calculated from the period of REF1 and REF2, and corresponds to the actual idle rotation speed _N1 during the explosion stroke of the No. 1 cylinder.

In this manner, in steps 4 to 7, after the explosion stroke of one cylinder is almost completed, the actual idle speed during that stroke is detected. This portion, together with the crank angle sensor 14, corresponds to idle rotation speed detection means.

For example, if the actual idle speed N ₁ of No. 1 cylinder during the explosion stroke is detected in step 5, then in step 9, the idle speed N ₄ of No. 4 cylinder immediately preceding in the ignition order (in the previous flow) is detected. detected).

If N ₄ > N ₁ , that is, if N ₁ is lower than N ₄ , in step 14, the integral correction value IADV1 of the ignition advance angle for the No. 1 cylinder is increased by a predetermined amount (for example, 1°). . Conversely, if N ₄ <N ₁ , that is, if N ₁ has increased compared to N ₄ , in step 15, the integral correction value IADV1 of the ignition advance angle for the No. 1 cylinder is increased by a predetermined amount (for example, 1°). ) Make it smaller.
This part corresponds to integral control means including comparison means. The initial value of integral correction values IADV1 to IADV4 is 0.
It is.

Generally, the ignition timing at idle is not at the optimal ignition timing MBT (for example, 40 to 50 degrees before top dead center), but is on the retard side of MBT (for example, 30 degrees before top dead center), so it is necessary to advance the ignition timing. If the angle is corrected to the angular side, the torque increases, and if the angle is corrected to the retarded side, the torque decreases.

Therefore, for example, if the actual idle speed of the No. 1 cylinder is smaller than the idle speed of the No. 4 cylinder immediately preceding it in the ignition order, increase the integral correction value IADV1 and adjust the next ignition advance angle ADV. In other words, the ignition timing is advanced to increase torque, thereby reducing the difference in idle speed between each cylinder.

Here, the integral correction value IADV1 for each cylinder is
IADV4 corresponds to the difference in the variation in explosive force between cylinders, so IADV1 to IADV4 should have positive and negative values centered around 0, but when there are load fluctuations due to electrical load or brakes, etc. It is conceivable that the whole will deviate significantly in the positive or negative direction.

Therefore, in steps 20 to 22, corrections are made so that the center of the variation in the integral correction values IADV1 to IADV4 is always zero.

That is, in step 20, the current ignition cylinder is No.
It is determined whether it is the No. 1 cylinder or not, and only when it is the No. 1 cylinder, the next steps 21 and 22 are executed. This is because the correction is made every two revolutions of the engine.

In step 21, the average value of integral correction values for all cylinders LADV=(IADV1+IADV2+IADV3+
Calculate IADV4)/4. This is the integral correction value
It represents the amount of offset from 0 of the center of variation in IADV1 to IADV4.

Therefore, in the next step 22, the above-mentioned integral correction values IADV1 to IADV4 for each cylinder are calculated.
Subtract LADV and correct the integral correction value. As a result, the center (average value) of the variations in the integral correction values IADV1 to IADV4 becomes zero. This step 20
22 corresponds to the correction value modification means.

Next, in step 23, the ignition advance angle ADV is set by searching from the engine speed N and the basic fuel injection amount Tp as described above. Here, the calculation processing period is
In the case of T ₂ , N ₁ is used as N, but the average value (N ₁ +N ₂ +N ₃ +N ₄ )/4 may also be used.

Next, in step 24, the current ignition cylinder is determined. Here, if the current calculation processing period is _T2 as in the above example, it is determined that the current ignition cylinder is the No. 2 cylinder. Also, the current calculation processing period is
In the case of T ₁ ', it is determined that the current ignition cylinder is the No. 1 cylinder. This part also corresponds to the means for determining the ignition cylinder.

Then, based on this determination, steps 25 to 2 are performed.
Branches to 8, and the integral correction value corresponding to the ignition cylinder
Correct the ignition advance angle ADV with IADV1 to IADV4.

That is, if the current calculation processing period is T ₂ ,
Since the ignition cylinder this time is the No. 2 cylinder, the process proceeds to step 26, and the ignition advance angle ADV set in step 23 is set to the already determined integral correction value IADV2 for the No. 2 cylinder. Add
Correct the ignition advance angle ADV. If the current calculation processing period is T ₁ ', the current ignition cylinder is the No. 1 cylinder, so the process proceeds to step 25, where the calculation processing period T is applied to the ignition advance angle ADV set in step 23. No. ₁ that has already been determined and stored in memory.
The ignition advance angle ADV is corrected by adding the integral correction value IADV1 for one cylinder. This part corresponds to the ignition timing correction means.

Thereafter, in step 29, the ignition advance angle ADV is set in the aforementioned counter, and ignition is performed at that ignition advance angle.

In this embodiment, the idle speed detected for a certain cylinder is compared with the idle speed detected for the immediately preceding cylinder in the ignition order, and control is performed to eliminate the difference. The detected idle rotation speed may be compared with the latest average value of the idle rotation speeds of all cylinders, and the control may be performed so as to approach the average value. In this case, N ₀
=(N ₁ +N ₂ +N ₃ +N ₄ )/4, then the comparison of N ₃ :N ₄ in step 8 in Figure 4 is N ₀ :N ₄ and the comparison of N ₄ :N ₁ in step 9 is N ₀ :N ₁ , step 10 N ₁ :N ₂ comparison to N ₀ :N ₂ , step 1
The comparison of N ₂ :N ₃ in 1 may be changed to N ₀ :N ₃ .

Further, the correction of the integral correction value in steps 21 and 22 may be performed not every two revolutions of the engine but every one revolution of the engine.

Idle control using such ignition timing correction control effectively works from the explosion caused by the ignition, so not only does responsiveness and control speed significantly improve, but the ignition timing can also be corrected for each cylinder.
Since the explosive power of each cylinder is made the same, it is possible to deal with variations in characteristics between cylinders, reducing fluctuations in idle speed between cylinders and reducing engine vibration, further improving idle stability. be able to.

Further, the idle control based on the ignition timing correction control for each cylinder according to the present invention may be used in combination with the idle speed feedback control (ISC) based on the conventional auxiliary air amount control.

<Effects of the Invention> As explained above, according to the present invention, each cylinder has its own ignition timing correction value, and the ignition timing is controlled in a direction that equalizes the explosive power of each cylinder during idling. The effect is that rotational fluctuations and engine vibrations can be reduced, and idle stability can be greatly improved.

In particular, the average value of the ignition timing correction values for all cylinders is calculated, and the ignition timing correction values for each cylinder are corrected by the same amount in order to make the average value 0. There is no risk that the correction value group will deviate as a whole, and good control can always be performed.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention.
Fig. 2 is a system diagram showing an embodiment of the present invention, Fig. 3 is a hardware configuration diagram of a control unit, Fig. 4 is a flow chart showing control contents, and Fig. 5 is a time chart showing control timing. . 1...engine, 10...ignition plug, 11...ignition coil,
12...distributor, 13...power transistor, 16...crank angle sensor, 30...control unit.

Claims (1)

[Scope of Claims] 1. In an internal combustion engine in which a control value for ignition timing by an ignition device is set and output to the ignition device according to engine operating conditions, an ignition cylinder determining means;
Idle rotation speed detection means detects the actual idle rotation speed during the explosion stroke for each cylinder, and an integral control means for increasing or decreasing the ignition timing correction value by a predetermined amount; and an integral control means for calculating the average value of the ignition timing correction values of all the cylinders, and adjusting the ignition timing correction value for each cylinder in the direction of zeroing the average value. An idle for an internal combustion engine, comprising a correction value correction means for correcting the same amount, and an ignition timing correction means for correcting the ignition timing control value by adding respective correction values for each cylinder and outputting the corrected value to an ignition device. Control device. 2. The integral control means includes a comparison means for comparing the idle speed detected for each cylinder with the idle speed of another cylinder detected immediately before, and adjusts the ignition timing for each cylinder according to the comparison result. An idle control device for an internal combustion engine according to claim 1, wherein the correction value is increased or decreased by a predetermined amount. 3. The integral control means includes a comparison means for comparing the idle rotation speed detected for each cylinder with the latest detected average value of the idle rotation speed of all cylinders,
The idle control device for an internal combustion engine according to claim 1, wherein the ignition timing correction value for each cylinder is increased or decreased by a predetermined amount in accordance with the comparison result. 4. The idle control device for an internal combustion engine according to any one of claims 1 to 3, wherein the correction value modification means performs the modification every predetermined rotation of the engine.