JPS6217369A - Ignition timing control method under idling of internal-combustion engine - Google Patents

Abstract

PURPOSE:To stabilize the idle rotation by correcting the ignition lead angle with the difference between target idle rotation and actual rotation multiplied by specific factor under specific condition of engine. CONSTITUTION:Under idle region where the engine cooling water temperature TW is higher than setting level TWIDIG, the ignition lead angle thetaIG is determined to be optimal for the detected operating condition. Then the difference between the target idle rotation and the actual idle rotation is obtained. Thereafter, it is multiplied by specific factor to obtain the final idle ignition lead angle thetaIG. The ignition timing is controlled on the basis of said corrected ignition lead angle thus to stabilize the idle rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for controlling ignition timing of an internal combustion engine during idling, and particularly to a method for controlling ignition timing during idling to accurately maintain engine speed at idle at a target idling speed. The present invention relates to a method for controlling ignition timing during idling of an internal combustion engine.

(Technical Background) When the operating state of the internal combustion engine is in the idle region, it is desirable that the internal combustion engine rotate stably at a target idle speed corresponding to the engine state. However, in reality, it may be difficult to maintain the target idle rotation speed constant due to load fluctuations.

(Prior art and problems) As a countermeasure to this problem, there is a technique that controls the engine speed at idle by controlling the advance/retard of the ignition timing, thereby maintaining the target idle engine speed. It is known from JP-A-52-153042 and the like. In the case of this technology, the actual rotation speed is detected, and when the actual rotation speed rises above the set target idle rotation speed, the ignition timing is retarded, and when the actual rotation speed falls below the target idle rotation speed, the ignition timing is retarded. When this happens, the ignition timing is advanced.

However, with this method of detecting the actual rotation speed and controlling the advance or retardation of the ignition timing using only the actual rotation speed as a parameter, the ignition timing is advanced or retarded regardless of the engine temperature. There is a possibility that inconvenience may occur at times. That is, when the engine is cold, the combustion state within the cylinder is often unstable, and in such cases, rotational fluctuations occur due to fluctuations in the combustion state. Therefore, even if the ignition timing is advanced or retarded in such a situation, it is difficult to accurately control the idle speed.

On the other hand, even when the engine temperature is above a predetermined value, stable rotation speed control is required by preventing rotation speed hunting caused by control delays.

(Object of the Invention) In view of the above-mentioned problems, the present invention provides an ignition system for an internal combustion engine during idling, which makes it possible to stabilize the rotation during idling and to accurately control the target idling speed. The purpose of this invention is to provide a timing control method.

(Structure of the Invention) In order to achieve the above object, the present invention provides an ignition timing control method for controlling the ignition timing of an air-fuel mixture based on an ignition advance value that is optimally determined according to operating parameters of an internal combustion engine. is in a predetermined idle region, detects whether the engine temperature is above a predetermined value, and when the engine is in the predetermined idle region and the engine temperature is above the predetermined value, The actual rotational speed of the engine is detected, the determined ignition advance value is retarded by a predetermined value, and the retarded point large advance value is further calculated as the difference between the target idle rotational speed and the detected actual rotational speed. is corrected by a value obtained by multiplying by a predetermined number, and the ignition timing is controlled based on this corrected ignition advance value.

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

FIG. 1 is a block diagram showing the overall configuration of an ignition timing control device to which the method of the present invention is applied, and the ignition timing control device controls, for example, the ignition timing of a four-cylinder internal combustion engine (not shown). Reference numeral 10 is a central processing unit (hereinafter referred to as rCPUJ), and various parameter sensors are connected to the input side of the CPU10 via an input circuit 11. More specifically, it is installed around the camshaft of the engine, for example, and is installed at a predetermined rank angle 1 before top dead center (TDC) on the compression stroke path of each cylinder. A To4 sensor 12 that generates a To4 signal pulse representing the reference crank angle position of each cylinder at 10° BTDC (for example, 10° BTDC) is connected to the CPU10 via a waveform shaping circuit 11a of the input circuit 11. The waveform shaping circuit 11a is T
The To4 signal pulse from the o4 sensor 12 is converted into a rectangular pulse (
The pulses are shaped into pulses s a 4 e s a J shown in FIG. 2 (,) and supplied to the CPU10. T24 sensor 13 is To
4 Sensors 12 are installed around the camshaft, and 24 sensors are installed at equal intervals (30" intervals in terms of crank angle) during one revolution of the camshaft, that is, two revolutions of the crankshaft (not shown).
Generates a pulse. T□ sensor 13 is waveform shaping circuit 11
connected to the CPU10 through the waveform shaping circuit 11b
The T24 signal pulses (pulses S3., S4° to 5451S2° in FIG. 2(b)) whose waveforms have been shaped are supplied to the cpUIO.

Further, an absolute pressure (PBA) sensor 14 detects the internal pressure PBA in the intake pipe (both not shown) downstream of the throttle valve of the engine. The input circuit 11 includes an intake air temperature (TA) sensor 16 that detects the intake air temperature TA, and an engine water temperature (Tw) sensor 15 that is installed in the cylinder peripheral wall filled with cooling water of the engine body and that detects the cooling water temperature (Tw). CPU10 through the level correction circuit 11C and A/D converter lid.
It is connected to the. The A/D converter lid is connected to the above-mentioned absolute pressure sensor 14. which is corrected to a predetermined voltage level by a level correction circuit 11c. Each analog signal from the intake air temperature sensor 16 and the engine coolant temperature sensor 15 is converted into a digital signal and the digital signal is supplied to the CPU10.

On the other hand, on the output side of CPU10, there is a drive circuit 20 that supplies coil energizing power to the primary coil 22a of the ignition coil 22.
is connected. A secondary coil 22b of the ignition coil 22 is connected to spark plugs 25a to 25d of each cylinder via a power distributor 24. Incidentally, a ROM 27 for storing calculation programs and the like and a RAM 28 for temporarily storing calculation results and the like are connected to the CPU 10 via a bus 26.

Next, the operation of the ignition timing control device configured as described above will be explained with reference to FIG.

First, the CPU 10 sets the crank angle stage (from the reference crank angle position of each cylinder) based on the To4 signal from the To4 sensor 12 and the T24 signal from the T24 sensor 13.
Hereinafter, this will be simply referred to as the "stage position").

That is, for example, the To4 signal signal pulse S in FIG. 2(a)
The T24 signal pulses S4° and S2° (Fig. 2(b)) detected immediately after the occurrence of
Assuming that the TDC signal at the end of the compression stroke of the cylinder and the second cylinder is generated, the CPU10 has To, the signal pulse Sa,
The reference crank angle position (TDC position) of the fourth cylinder is detected by the T24 signal pulse S4° inputted immediately after the occurrence of
The 0th stage position (the period between the rising times of pulses S4° and S4□ in FIG. 2(b) is defined as the 0th stage position; the same applies hereinafter) before the pulse S2° generation position of ) is detected. Then, the T24 signal pulse S4□ which is input after that
, #1 stage position, #2 stage position by S42,
Detect...

When the CPU 10 detects a predetermined stage position (for example, the first stage position), it calculates the ignition advance value θig, the ignition coil energization time TON, etc. based on the output signals from the various parameter sensors described above.

The ignition advance value θig is calculated based on the following equation (1).

O1g = θL g MAI) + θC (1) Here, the ignition advance value θig is the crank angle from the reference crank angle position (for example, the crank angle position where the T24 signal pulse S2° in Fig. 2 (b) is generated). θigMA
R is the basic ignition advance angle, and its value is the engine speed Ne
and a parameter representing the engine load, for example, the intake pipe absolute pressure PBA. Specifically, R
N e -P [I A-〇ig] stored in OM27
A value corresponding to the detected absolute pressure value PBA and the detected engine speed value Ne is read out from the map as the oigMAP value.

The engine rotation speed Ne is calculated every time the T24 signal pulse is input, and this method is calculated as the reciprocal of the value Me obtained by counting the number of pulses of a predetermined clock in the pulse generation time interval of the T24 signal. Calculated. θ
Q1< is an advance/retard angle correction variable value determined by water temperature Tw, intake air temperature TA, etc.

Note that when the engine is in a predetermined idle state, the CPU 10 corrects the ignition advance value θig obtained as described above. Details of this will be described later.

Next, the CPU10 activates the temporary coil 22 of the ignition coil 22.
Calculate the energization time TON of a. This energizing time TON
is set to an optimal value in order to prevent coil overheating and misfire at the spark plug, and is generally set at the engine speed Ne.
It is found as a function of

Next, the CPU 10 calculates the energization start timing Tcg and the energization stop timing Tig of the secondary coil 22a from the ignition advance value θig and the energization time TON obtained as described above. First, the crank angle position at which the primary coil 22a should start being energized from the 1st ignition advance value θig and the energization time T ON (see Fig. 2).
The position corresponding to time t1 in c) is calculated backwards from the reference crank angle position to determine which stage position the crank angle position at which energization should start is located. Then, T of the determined stage position (#2 stage position in the illustrated example)
24 signal pulse input point to (Figure 2 (C))
The time required for the rotation of the crankshaft to reach the crank angle position at which energization should start is determined from the above, and this time is determined as the energization start timing Tcg. Similarly, one ignition advance value θi
Crank angle position I at which energization of the coil 22a should be stopped from g! It is determined which stage position (position corresponding to time t1 in FIG. 2(c)) is located. Then, T24 of the determined stage position (#4 stage position in the illustrated example)
The time required for the rotation of the crankshaft to reach the crank angle position at which the energization should be stopped is determined from the time t2 when the signal pulse is input, and this time is defined as the energization stop timing Tig.

When the CPU10 detects the T24 signal pulse (S,, ) at the stage position where the coil 22a should start energizing (
The energization counter provided inside the CPU l0 waits for the energization start time T c g to elapse from the time t to ), and supplies the energization control signal to the drive circuit 20 when the energization start time Tag has elapsed (time ti). .

Then, when the T24 signal pulse (S, , ) at the stage position where the energization of the coil 22a should be stopped is detected (time tz), the energization stop counter provided inside the CPU10 determines the elapse of the energization stop time Tig. When the first energization stop time Tig has elapsed (time ta), the supply of the energization control signal to the drive circuit 2o is stopped.

While the energization control signal from the drive circuit 2011 CPU 10 is supplied, the primary coil 22 of the ignition coil 22
Supply coil energizing power to a. When the supply of coil energizing power from the drive circuit 20 is cut off, a high voltage is generated on the secondary coil 22b side of the ignition coil 22, and this high voltage is transmitted to the ignition plug (in the illustrated example) via the power distributor 24. Spark plug 25
c) and a spark discharge, ie ignition, occurs at the spark plug.

FIG. 3 is a flowchart showing a procedure executed in CPU10 to set the ignition advance value θig during engine idling according to the present invention.

In step 30, the engine cooling water temperature Tw as the engine temperature is set to a set temperature TWIDIG (for example, 40°C).
Determine whether or not the value is greater than or equal to the above. If the engine coolant temperature Tw is less than the set temperature Twto+a, the program is terminated without executing the following steps. This is the engine coolant temperature T even when the engine is idling.
When v is less than the set temperature TVIDIG, the combustion state within the cylinder is often unstable, and in such cases, rotational fluctuations occur due to fluctuations in the combustion state.6 Therefore, the ignition timing is controlled. Even if you try, it is difficult to control the idle rotation accurately.

On the other hand, if the answer is affirmative (Yes), the process proceeds to the next step 31, and it is determined whether the engine is in the idle region. In this case, it is determined whether or not the engine is in the idle region when the engine speed Ne is low (for example, 900 rpm).
(detected by the throttle valve opening (θ〒H) sensor 29) when the throttle valve opening θT14 is below the idle opening θIDL). It may be determined that the engine is in the idle region when the engine speed is low and the pressure PEA in the intake pipe is on the lower load side than a predetermined value.

If the answer is negative (No), the program ends.

Further, when the engine is in the idle region, the process proceeds to the first step 32, and a predetermined value ΔθIGIDL is subtracted from the ignition advance value θI9 calculated based on the above formula (1) so as to be optimal for the detected operating state. The difference value is set as a new ignition advance value θig.

Next, the process proceeds to step 33, where a value M corresponding to the reciprocal of the engine's target idle speed Ne! Ml to read IDIG! The IDIG value is MHI□ as shown in FIG. 4, which is stored in the RON 27. - Read from Twtoto table.

The table shows that the higher the T'WIDIG value, the more M! IDIG
The value is set to a large value, that is, the Ne value is set to a small value.

When the reading of the MImIDIG value is completed, the process proceeds to the next step 34, where the value ME corresponding to the reciprocal of the actual engine speed Ne is read.
Ml! read out in the previous step 33! IDIG value difference ΔM
Calculate E.

Next, the process proceeds to step 35, where a predetermined count φθ is added to the difference ΔM.
ME is multiplied, this value is subtracted from the ignition advance value θig obtained in step 32, and the subtracted value is again set as the ignition advance value θig.
shall be. This ignition advance value θig becomes the final idle ignition advance value θig.

As shown in FIG. 5, when the ΔME value is a positive value, the advance angle is corrected to the advance side, and when it is a negative value, the angle is retarded to the retard side.

Based on the ignition advance value θig obtained in this way, C:P
Ulo calculates the energization start timing Tag and energization stop timing Tig of the primary coil 22a during idle.

Note that the predetermined value ΔθIGIDL differs depending on the engine, and is a numerical value determined experimentally from the fluctuation state of the rotation of the applied engine during idling. Similarly to the predetermined value ΔθifD, the predetermined count φOMε is also experimentally determined from the fluctuation state of the rotation during idling of the applied engine to a value that does not cause hunting in the rotation speed due to control delay.

Generally, it is about 0.08 to 0.12 per rotation.

(Effects of the Invention) In summary, the method for controlling the ignition timing during idling of an internal combustion engine according to the present invention controls the ignition timing of the air-fuel mixture based on the ignition advance value that is optimally determined according to the operating parameters of the internal combustion engine. In the ignition timing control method, it is determined whether the engine is in a predetermined idle region, and whether the engine temperature is equal to or higher than a predetermined value. is above the predetermined value, the actual engine speed is detected, the determined ignition advance value is retarded by a predetermined value, and this retarded ignition advance value is further set as the target idle speed. The present invention is characterized in that the difference from the detected actual rotational speed is corrected by a value obtained by multiplying by a predetermined coefficient, and the ignition timing is controlled based on the corrected ignition advance value.

Therefore, even if the engine is in the idle region, ignition timing control during idle is performed only when the engine temperature is above a predetermined value or when the engine condition is relatively stable, making it possible to control the idle speed stably. Therefore, when executing the ignition timing control during idling, a correction value is calculated by multiplying the deviation ΔMB by a predetermined coefficient determined experimentally, taking into account the fluctuation of the idling rotation. This has the advantage that it is possible to make corrections that suit the fluctuations in the idle rotation, thereby further stabilizing the idle rotation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an ignition timing control device for an internal combustion engine to which the present invention is applied, and FIG.
FIG. 3 is a timing chart showing the generation time changes of the TO4 signal, T, 4 signal from the T24 sensor, and the ignition coil energization control signal, and FIG. The flow chart shown in FIG. 4 shows the value M corresponding to the reciprocal of the target rotation speed.
! E I D I G-Engine coolant temperature TWIDIG
FIG. 5 is a graph showing the relationship between the ignition advance setting value θig at idle and the actual engine speed No. FIG. 10...Central processing unit (CPU), 12...T
o. Sensor, 13...T2. Sensor, 14... Intake pipe absolute pressure (PBA) sensor, 15... Engine coolant temperature (Tw) sensor, 20... Drive circuit, 22... Ignition coil, 25a to 25d... Spark plug , 29... Throttle valve opening (θTl() sensor.

Claims (1)

[Claims] 1. In an ignition timing control method that controls the ignition timing of an air-fuel mixture based on an ignition advance value that is optimally determined according to operating parameters of an internal combustion engine, the method includes determining whether the engine is in a predetermined idle region or not. detect whether the engine temperature is above a predetermined value, and when the engine is in the predetermined idle region and the engine temperature is above the predetermined value, detect the actual rotation speed of the engine. Then, the determined ignition advance value is retarded by a predetermined value, and this retarded ignition advance value is further corrected by a value obtained by multiplying the difference between the target idle rotation speed and the detected actual rotation speed by a predetermined coefficient. and controlling the ignition timing based on the corrected ignition advance value. 2. A patent characterized in that the engine is determined to be in the predetermined idle region when the engine speed is below a predetermined value and the opening degree of a throttle valve disposed in the intake system of the engine is below a predetermined opening degree. A method for controlling ignition timing during idling of an internal combustion engine according to claim 1. 3. The engine is determined to be in the predetermined idle region when the engine speed is below a predetermined value and the pressure in the intake pipe is on the lower load side than the predetermined value. A method for controlling ignition timing during idle of an internal combustion engine. 4. The ignition timing control method during idling of an internal combustion engine according to claim 1, characterized in that the engine cooling water temperature is set to the engine temperature. 5. The ignition timing control method during idling of an internal combustion engine according to claim 1, wherein the target idle rotation speed is set according to engine cooling water temperature.