JPS60216067A - Ignition timing controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent knocking and the damage of engine thus to improve the engine performance as high as possible by the ignition timing characteristic for normal octane number fuel upon entering into high rotary speed condition piror to complete decision which of regular octane number fuel or high octane number fuel is employed. CONSTITUTION:In this case, it is set to employ high octane number fuel. An electronic control unit ECU20 will perform decision of regular fuel injection during 500 ignitions after engine start. Occurrence of large knocking during 100 ignitions after lagging the lead angle correction level thetaK to the lag angle side limit thetaKMIN is detected and if it will exceed over predetermined level ''10'', it is decided that regular fuel is injected. Upon entering into high rotary speed condition prior to complete decision of regular fuel injection, the basic ignition angle thetaBSF is obtained from relatively lagged ignition timing characteristic for regular fuel to obtain the final ignition lead angle theta=thetaBSE+thetaK where thetaK is the lead angle correction level.

Description

TECHNICAL FIELD The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to a device capable of performing ignition timing control suitable for fuels of class 2'a having different octane numbers.

Prior Art In engines where there is a risk of using ZWI fuels with different octane numbers, such as normal octane fuel (hereinafter referred to as reguiler fuel) and high octane fuel (hereinafter referred to as high-octane fuel), two types of fuel suitable for each fuel are used. One of the ignition timing characteristics is selected depending on the fuel used, and the ignition timing is controlled accordingly.

Determination as to whether the fuel currently being used is regular fuel or high-octane fuel is automatically performed according to the detection output of the Nozuku sensor. The problem with such a system that automatically determines the octane number is which ignition timing characteristic should be used for control until the determination is complete. If relatively retarded ignition timing control for the regulator fuel is performed until the determination is completed, if high-octane fuel is used, engine performance will be sacrificed until the determination is completed.

Furthermore, if relatively advanced ignition timing control for high-octane fuel is performed until the determination is completed, a large amount of knocking will occur if the engine is in a high rotational speed state when low-performance fuel is used. At high rotational speeds, engine vibrations other than knocking become large, making it difficult to control knocking, resulting in significantly large knocking.
In the worst case, the engine may be damaged.

OBJECTS OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems of the prior art, and its object is to avoid knocking and consequent engine damage when fuels with different octane ratings are used. Moreover, it is desirable to provide an ignition timing control device that can maintain engine performance as high as possible.

Structure of the Invention The structure of the present invention that achieves the above-mentioned object will be explained using FIG. ignition timing is calculated by selectively using the ignition timing characteristic for normal octane fuel or the ignition timing characteristic for high octane fuel according to the determination result; means d for detecting that the engine a is in a high rotational speed state; and means e for detecting that the engine a is in a high rotational speed state; The ignition timing calculating means d is characterized by comprising means f for forcing the ignition timing to be calculated using the ignition timing characteristics for normal octane fuel.

Example The present invention will be explained in detail by way of examples below.

FIG. 2 shows an example of the microbunpi device as an embodiment of the present invention.
The figure shows an internal combustion engine that performs ignition timing control. In the same figure, 10 is the cylinder block of the engine, and 12 is a part attached to the cylinder block 10. The knock sensor 12 is a well-known device that is composed of, for example, a piezoelectric element or an electromagnetic element, and converts mechanical vibrations into electrical amplitude fluctuations. Distripy&-
The motor 14 is provided with crank angle sensors 16 and 18. The crank angle sensor 16 detects 24 noculus for each revolution of the distributor shaft, so the crank angle sensor 16
Generates a nollus every 0°. The crank angle sensor 18 is for cylinder discrimination (720
Generates one elbow for each For example, this occurs at a position slightly before the compression top dead center of the first cylinder. Knock sensor 1
2, and the electric signals from the crank angle sensors 16 and 18 are sent to an electronic control unit (ECU) 20.

The ECU 20 also receives the intake air flow rate Q of the engine from an air flow sensor 24 installed in the intake passage 22 of the engine.
A voltage signal corresponding to the voltage is sent.

On the other hand, the ECU 20 outputs an ignition signal to the igniter 26, and the igniter 26 outputs an ignition signal to the ignition coil 28.
intermittent control of the primary current. The high voltage current generated by the ignition coil 28 ignites each cylinder via the distributor 14! As a result, an ignition spark is formed at the ignition timing according to the ignition signal.

The engine is usually equipped with various other sensors that detect operating state parameters, and the ECU 20 controls the opening and closing of the fuel injection valve 32 to control the amount of pressurized fuel injected from a fuel system (not shown). Control is also performed, but since these are not directly related to the present invention, they will be omitted in the following explanation.

FIG. 3 shows an example of the configuration of the ECU 20 shown in FIG. The voltage signal from the air flow sensor 24 is
Analog multiplexer (MPX) 2 through 0m
0b, is selected in accordance with an instruction from the microcombi converter 20e, and is applied to the analog-to-digital converter 20e. Input data representing the intake airflow fiQ converted into a two-pass signal by the νΦ converter 20c is input into the microcomputer via the input/output port 20d.

The pulses from the crank angle sensor 16 at every 30° crank angle and the pulses at every 720° crank angle from the crank angle sensor 18 are waveform-shaped in the waveform shaping circuit 20e and then sent to the microcombination via the input/output port 20f. It is taken into the eta.

The output signal of the knock sensor 12 is transmitted through a buffer that performs impedance conversion and a knocking-specific frequency band (7 to 8
It is sent to the Φ converter 20h through an input circuit 20g consisting of a band filter with a pass band of Incorporated into a microcomputer.

On the other hand, the input/output port 20f from the microcontroller
Furthermore, an ignition signal is outputted to the igniter 26 via the drive circuit 201, and the above-mentioned ignition process is thereby performed.

The microcomputer includes the aforementioned input/output ports 20d and 20f, a central processing unit (CPU) 20J, a random access memory (RAM) 20k, a read-only memory (ROM) 20t, and a clock generation circuit and memory (not shown). It mainly consists of a control circuit and a 20 m path connecting these, If), and ROM2.
Ignition timing control processing, which will be described later, is executed in accordance with the control glodarum stored in advance at 0t.

Note that the engine of this embodiment is normally set to inject high-octane fuel, and performs ignition timing control to deal with the accidental injection of regular fuel.

The operation of the micro combi store will be explained below using a flowchart.

FIG. 4 shows part of the processing performed during the initial routine. When the engine ignition switch is turned on, the CPU 20J executes steps 100 and 101. In step 100, the determination completion flag FJCO, which is set when the determination operation for determining whether regular fuel has been injected or not, is completed is reset to "0".

At step 101, the count value C1*CJI used in the processing routines of FIGS. 5 and 6 is reset to 10''.

FIG. 5 shows a portion of the TDC interrupt routine that is executed for each ignition according to the compression top dead center of each cylinder for knock control. In step 200, knocking control is performed in an operating region, for example, in the middle.

Determine whether or not the vehicle is in the low speed driving range. In the case of the knocking control region, the count value C1 is increased by one in Stella f201. When not in the knocking control area,
Skip step 201 and proceed to the next Stella f202.

In step 202, it is determined whether the color/gravity value C1 is 500 or more. When CI≧500, that is, when the engine rotates for more than 500 ignitions in the knock control region after the ignition switch is turned on, Stella f
In step 203, this count value C1 is defined as 500, and in Stella f204, the judgment completion flag FJCOM is set to "1".
set. The process then proceeds to step 205. Also, 50
When it does not rotate to 0 ignition (C, (50(1))
Proceeds directly from ST.zo 202 to STELLA f205. Step F205 is a part for performing regular fuel injection determination processing, and this determination processing is performed by the processing routine shown in FIG. 6 or M7. As described above, according to the processing routine shown in FIG. 5, the regular fuel injection determination is performed for 500 ignitions after the engine is started.

Next, the regular fuel injection determination process shown in FIG. 6 will be explained. First, in Stezo 300, the CPU 20j is
Determine whether the flag 'MEN, which is set when the ignition timing advance correction value 0K based on knocking control is retarded to the minimum value 0□, which is the retard limit, is 11#. . If FMIN=0, the process advances to step yf301, where it is checked by a well-known method based on the signal from the knock sensor 12 whether or not it has been determined that a blowfish has occurred.

If knocking does not occur, the process proceeds to step f302, where the advance angle correction value 0 is increased by α. That is, processing is performed in the advance direction.

If knocking has occurred, proceed to step 303;
The minimum value θIC at which the advance angle correction value θ is the limit on the retard side.
Determine whether the value is greater than or equal to MIN. If θ≧θ□, the program jumps to step f306, decreases the advance angle correction value θK by β, and performs retard processing. If θK<θKMIN, the process proceeds to step 306 after steps 304 and 305, and retard processing is performed. In step 304, the above-mentioned flag F
MINt- is set to "l", and in step 305, an initial value "100" is set to the count value C1 used in later processing.

In this way, even if the advance angle correction value θ is decreased and the ignition timing is controlled in the retarded direction due to the occurrence of knocking, knocking still occurs, and when Ojc is reduced to its retard limit, the advance The angle correction value θ is no longer adjusted;
The processing in steps 307 to 314 exclusively determines whether or not regular fuel has been injected.

In step 307, the count value Ct is decreased by 11'', and in the next step 308, this count value CS is
``Determine whether it is greater than or equal to 0#0#.

C! If ≧0, the process advances to step 309 and it is determined whether or not a large number or king has occurred. This determination is performed in accordance with the output of the knock sensor 12 using a well-known method. Each time a large knock occurs, the process advances to step 310 and the counter value Cs is incremented by one. The initial value of C fable is @1
Therefore, Stella 13090 discrimination is performed 100 times (100 ignitions) after 'x<'xiirs, and the number of times that large knocking occurs during that time becomes the count value C3.When 100 ignitions pass, C3 is determined. Since the count value is 0, the process proceeds to step 311, where it is determined whether the count value C3 exceeds "10".
It is determined that regular fuel has been injected and step 3
12, and sets the flag FIL indicating that to "1#." Next, in step 313, the flag FMl is set to "1#".
) If @0#, reset count value C3 to 10”
Reset to . If C3≦lO, step 312
Skip over and proceed to step 313. As described above, according to the processing in steps 307 to 314, the advance angle correction value θ is set to 10 after the advance angle correction value θ is retarded at the retard side limit 0 IN t.
The number of times C1 that one large knock occurs between zero ignitions is detected, and it is determined that regular fuel is being injected when this is equal to or greater than a predetermined value ""10#10#.

Next, the reguiler fuel injection determination process shown in FIG. 7 will be explained. The processing routine of FIG. 7 is the processing routine of FIG. 6 with steps 400 and 401 added. That is, if it is determined in step 301 that knocking has occurred, the process proceeds to step 400, and when the engine rotational speed N is 400°
It is determined whether or not the rotation speed is less than N (4000 rpm, that is, when it is in the medium and low rotation speed region,
I am trying to process this. In the case of N2200 Orpm, the process advances to step 302. Also, step 308
Even when it is determined that C snow ≧ 0, it proceeds to step 401 to determine whether N (4000 rpm), and proceeds to step vf309 only when it is in the medium and low rotation speed region.Steps 400 and 401 are added in this way. As a result, the leg error fuel injection judgment operation is performed only in the medium and low rotation speed range where knocking control is best.If this judgment operation is performed in the high rotation speed range, knocking due to valve knocking etc. This noise could lead to an erroneous determination that regular fuel is being injected even though high-octane fuel is being injected.

FIG. 8 shows processing that may be performed in place of steps 309 and 310 of the processing routines of FIGS. 6 and 7. Ste, f500 is Ste.

In exactly the same way as step 309, it is determined whether or not large knocking is occurring. [large], if a king occurs, it is determined in step 501 whether or not knocking occurs continuously.
Determine by Stella f50 if there is continuous knocking
In step 2, the count value is increased by 12", and if there is no continuous knocking, the count value is increased by @1" in step 503. In this manner, by changing the amount of increase in the count value Cm depending on the presence or absence of continuous knocking, it is possible to perform a highly accurate Ray-2 fuel injection determination process.

FIG. 9 is a processing routine for calculating ignition timing. C
The PU 20J executes the process shown in FIG. 9 during the main routine. First of all, in f600, RAM20
From a predetermined position in , the rotational speed N and φ calculated in advance from N and the intake air flow rate Q and stored in the RAM 20 k are taken.

In the next step 601, the above-mentioned determination completion flag FJCO is
It is determined whether the leg error fuel injection determination operation has been completed by checking whether M is set to "l".

If the determination operation has been completed (FJCOM"' 1), the process advances to step 602, and it is determined whether regular fuel is being injected by checking whether the flag FR is set to @l#.

If FR=1, it is regular fuel injection, so the process proceeds to step 603, and the basic ignition advance angle 'ms+m is calculated using the ignition timing characteristics for regular fuel.

Further, if FR=0, since no reguiler fuel has been injected, the process proceeds to step 604, and the basic ignition advance angle θmgm is calculated using the ignition timing characteristics for high-octane fuel. That is, R
Inside the OM20, there is a function table suitable for high-octane fuel of θmsx for N,i as shown in FIG. is stored in advance.

In Stella f603, θ□ is calculated using the regular fuel function table shown in Figure 1 Ob, and in step 604, using the high octane fuel function table shown in Figure 10a. Of course, in that case interpolation methods are used. θ□ for high-octane fuel in Figure 10a than for regular fuel in Figure 10b.

It is well known that energization is set so that the angle is on the advance side.

Now, in step 601, if it is determined that the regular fuel injection determination operation has not been completed (FJCOM=0
), that is, from the start of the engine.

If the engine does not rotate until 500 ignitions in the King control area, proceed to Step 05. In Step 05, it is determined whether the rotation speed N at that time exceeds 500 rpm. Stella f if N≦500Orpm
Proceeding to 604, 0□8 is determined by the function table for high-octane fuel. However, N > 5000 rp
If the rotation speed is as high as m, the speed is 0.
Proceed to step 3 and use the function table for regular fuel to determine θ
, will be charged.

In this way, if the engine reaches a high rotational speed before the regieler fuel injection determination operation is completed, the basic ignition advance angle θII□ is set using the relatively retarded ignition timing characteristic for regieler fuel.

In the next step, f606, the advance angle correction value θ obtained in the processing routine of FIG. 6 or 7 is fetched from the RAM 20k, and in step 607, the advance angle correction value θ is read. The final ignition advance angle θ can be determined from θ=θ, 88+03. The ignition advance angle 0 determined in this way is set to R in step 608.
AM 20 k at a predetermined location. This ignition advance angle θ is read by an interrupt processing routine executed at a predetermined crank angle position, and the ignition advance angle θ is read out by an interrupt processing routine executed at a predetermined crank angle position.
It is given according to the Since this method of setting the ignition signal is well known, its explanation will be omitted in this specification.

In addition, in the embodiment described above, the engine is set to be compatible with high-octane fuel, and the determination is made when the engine uses regieler fuel, but which fuel is compatible is not set in advance. The present invention can also be applied to an engine in which the ignition timing characteristics adapted to the injected fuel are used after determining the fuel to be injected.

Effects of the Invention As explained in detail above, according to the present invention, if the rotational speed reaches a high speed state before it is determined whether normal octane fuel or shotgun fuel is being used, normal octane fuel is used. Since the ignition timing characteristics of the engine are used, it is possible to prevent knocking and engine damage that would occur if fuels with different octane numbers were used.

Furthermore, engine performance can be improved as much as possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a schematic diagram of an embodiment of the present invention, Fig. 3 is a block diagram showing the structure of the ECU shown in Fig. 2, and Figs. FIG. 10a is a flowchart of a portion of the control program. FIG. 10b is a diagram showing a basic ignition advance angle function table. DESCRIPTION OF SYMBOLS 10... Cylinder knock, 12... Knock sensor, 14... r2 trivitor, 16.18... Crank angle sensor, 20... ECU, 24... Air flow sensor, 26...Igniter, 28...Ignition coil, 30...Spark plug. Patent applicant Toyota Motor Corporation Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Sou Matsushita Akira Yamaguchi Patent attorney Masaya Nishiyama Figure 1 Figure 4 Figure 5 Figure 8 Figure 9 Figure 10a. . . Job diagram

Claims (1)

[Scope of Claims] 1. Means for detecting the occurrence of knocking in an engine; means for determining whether normal octane fuel or high octane fuel is being used according to the output of the knocking detection means; means for calculating the ignition timing by selectively using the ignition timing characteristic for normal off-temperature fuel or the ignition timing characteristic for high octane fuel according to the result; means for detecting that the engine is in a high rotational speed state; means for controlling the ignition timing calculation means to calculate the ignition timing using the ignition timing characteristic for normal octane fuel when it is detected that the engine has reached a high rotational speed before the determination by the means is completed; An ignition timing control device for an internal combustion engine, comprising: 2. Claim 1, wherein the determination means includes means for detecting that the engine is in a medium-low rotation speed state, and performs the determination operation only when the engine is in a medium-low rotation speed state. The ignition timing control device described in .