JP2528168B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition timing control device for an internal combustion engine, and in particular, an ignition timing suitable for a high octane fuel and an ignition timing suitable for a low octane fuel are preset. The present invention relates to an ignition timing control device.

2. Description of the Related Art Most of internal combustion engines for automobiles in recent years have an ignition timing set on the assumption that a low octane fuel (so-called regular fuel) is used. Therefore, even if a high-octane fuel (so-called high-octane fuel) is used in this type of internal combustion engine, the ignition timing cannot be advanced enough,
The advantages of high-octane fuel cannot be fully exerted in terms of thermal efficiency and output.

It is also possible to set the ignition timing on the assumption that high-octane fuel is always used, but if regular fuel is mistakenly used for this type of internal combustion engine, knocking may occur.

Therefore, conventionally, it is determined whether the fuel used is high-octane fuel or regular fuel based on the occurrence of knocking, and the ignition timing control is performed by switching between the high-octane basic ignition timing and the regular basic ignition timing according to the determination. There are things I tried to do.

For example, in Japanese Unexamined Patent Publication No. 60-104774, the basic ignition timing for high octave is selected in the initial state, and when the occurrence frequency of knocking is a certain value or more, it is determined to be regular fuel, and the regular fuel is used. There is described an ignition timing control device adapted to switch to a basic ignition timing for use.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional ignition timing control device, when the one basic ignition timing is switched to the other basic ignition timing, the final ignition timing abruptly changes. For example, when regular fuel is used to start operation at the high ignition basic ignition timing, at some point during operation, the high ignition basic ignition timing is suddenly retarded to the regular basic ignition timing. As a result, the engine output changes suddenly, which causes discontinuity in the operation of automobiles,
There is a risk of giving an occupant a discomfort.

Further, in the case where the basic ignition timing characteristic is switched depending on the knocking occurrence frequency as described above, it is very difficult to set the switching reference value, and an erroneous determination is likely to occur.

Means for Solving the Problems The present invention has been made to solve the above problems, and as shown in FIG. 1, a regular basic ignition for setting a regular basic ignition timing according to operating conditions. Timing setting means 1 and high-octane basic ignition timing setting means 2 for setting high-octane basic ignition timing according to operating conditions
And a selection means 3 for selecting either the regular basic ignition timing or the high-octane basic ignition timing as the basic ignition timing, and the final ignition timing is determined by adding the ignition timing correction amount to one of the selected basic ignition timings. Ignition timing correction means 4, knocking detection means 5 for detecting the occurrence of knocking of the internal combustion engine, the ignition timing correction amount is increased or decreased according to the presence or absence of knocking, and this is initialized at the time of regular / high-octane switching of the basic ignition timing. The correction amount calculating means 6 for converting the final ignition timing to the other basic ignition timing which is not selected at that time, and based on the comparison, the selection means 3 is switched to when the both match. And a switching means 7 for giving a command. still,
Reference numeral 8 denotes an ignition device that ignites according to the final ignition timing.

Operation For example, when the selection means 3 is in the high-octane selection state, the ignition timing is determined based on the high-occurrence basic ignition timing set on the relatively advanced side. That is, the final ignition timing is determined by adding the ignition timing correction amount to the high-octane basic ignition timing, and the ignition device 8 ignites accordingly.
Here, if regular fuel is used, knocking is likely to occur, so the ignition timing correction amount gradually decreases with the occurrence of knocking, and the final ignition timing gradually retards. And the final ignition timing after this correction is
If it matches the regular basic ignition timing at that time, it is determined that the fuel used is regular fuel, and the selection means 3 is switched to the regular side. Therefore, thereafter, the ignition timing is controlled by using the regular basic ignition timing which is set relatively late. Further, at this time, the ignition timing correction amount is initialized to zero. Therefore, the final ignition timing is continuous regardless of the switching of the basic ignition timing from high-octane to regular.

Conversely, when high-octane fuel is used in the regular selection state, knocking is less likely to occur, so the ignition timing correction amount gradually increases and the final ignition timing advances. If the corrected final ignition timing coincides with the high ignition basic ignition timing at that time, it is determined that the fuel used is high octane fuel, and the selection means 3 is switched to the high octave side. Also in this case, the ignition timing correction amount is initialized at the time of switching and becomes 0, so that the final ignition timing is still continuous.

Second Embodiment FIG. 2 is a structural explanatory view showing a mechanical structure of an embodiment of an ignition timing control device according to the present invention.

In the figure, reference numeral 11 indicates an in-line four-cylinder engine as an example. In order to detect knocking occurrence of each cylinder individually, an in-cylinder pressure sensor is used as a knocking sensor for each cylinder.
13 are provided. The in-cylinder pressure sensor 13 is formed in a washer shape using, for example, a piezoelectric element, and is attached to the ignition plug 12 mounting portion of each cylinder. The output signal of the in-cylinder pressure sensor 13 is input to the knocking processing circuit 24 of the control unit 19, and the knocking signal is extracted here to be used for knocking detection.

Further, in the intake passage 14 of the internal combustion engine 11, an air flow meter 15 for detecting the engine intake air amount is arranged. The throttle valve 16 downstream of the air flow meter 15 is equipped with an idle switch 17 that issues an ON signal when the throttle valve 16 is in a substantially fully closed position, that is, an idle position. The detection signal of the air flow meter 15 and the detection signal of the idle switch 17 are the same as those of the control unit.
It has been entered in 19. The idle switch 17 is turned on.
At the time of idling, the idling control different from the normal ignition timing control is executed.

Reference numeral 18 denotes a crank angle sensor that detects the rotation of the crankshaft of the internal combustion engine 11.
18 is a pulse signal (PO
S signal) and a pulse signal (REF signal) for each crank angle of 180 ° for detecting the predetermined position before compression top dead center of each cylinder are output to the control unit 19.

The control unit 19 uses a digital microcomputer system and performs various arithmetic processes.
CPU20, R that stores control programs and fixed data
The main components are an OM 21, a RAM 22 for temporarily storing various data, an I / O port 23, and the like. The regular basic ignition timing and the high-octane basic ignition timing are provided in the ROM 21 in the form of a data map having the engine speed and the load (for example, the basic fuel injection amount Tp) as parameters.

Reference numeral 25 indicates an ignition device including an ignition coil, a power transistor, etc.
The cylinders are operated in accordance with the final ignition timing determined in step 1 to sequentially ignite each cylinder.

Next, the flowcharts of FIGS. 3 to 5 show a control program executed in the control unit 19, and the ignition timing control in the above embodiment will be described below with reference to this flowchart.

The flowchart of FIG. 3 shows a main program for ignition timing control, which is executed, for example, each time each cylinder is ignited.

First, in step 1, the high ignition basic ignition timing TADVH corresponding to the engine operating conditions at that time is set. The high-octane basic ignition timing TADVH is set on the basis of a high-octane basic ignition timing map in which the load and the rotational speed of the internal combustion engine are used as parameters. Further, in step 2, similarly, the regular basic ignition timing TADVR corresponding to the engine operating condition at that time is set. This regular basic ignition timing T
ADVR is also set based on the regular basic ignition timing map with the load and the engine speed of the internal combustion engine as parameters. Of course, the basic ignition timing for high-octane
TADVH is set ahead of regular basic ignition timing TADVR.

Then, in step 3, the state of the type determination flag FHIOC indicating the fuel type is determined. This type determination flag FHIOC
Is "1" when it is determined that the fuel used is high-octane fuel by the type determination program described later, and "0" when it is determined to be regular fuel. Therefore, if the type determination flag FHIOC is "1", the routine proceeds to step 4, where the high ignition basic ignition timing TADVH is selected as the basic ignition timing TADV. If it is "0", the routine proceeds to step 5, where the regular basic ignition timing TADVR is selected as the basic ignition timing TADV.

In step 6, the final ignition timing SETADV is determined by adding the ignition timing correction amount KNKCS for avoiding knocking to the basic ignition timing TADV thus selected. Then, in step 7, the final ignition timing SETADV is set in the register of the I / O port 23.

Actually, this ignition timing control is executed for each cylinder, and ignition is performed at the optimum final ignition timing for each cylinder.

Here, the ignition timing correction amount KNKCS is sequentially given according to the knocking control program shown in FIG.
This knocking control program is executed, for example, immediately after ignition of each cylinder, reads the knocking signal obtained from the detection signal of each in-cylinder pressure sensor 13 in step 11, and determines whether knocking occurs in step 12. . Then, if knocking has occurred, the routine proceeds to step 13, where a constant amount D1 is subtracted from the previous ignition timing correction amount KNKCS to correct it to the retard side. If knocking has not occurred, the routine proceeds to step 14, where a fixed amount D2 is added to the previous ignition timing correction amount KNKCS to correct it to the advance side. That is, if knocking continues to occur, the ignition timing correction amount KN
KCS gradually decreases, and as a result, the final ignition timing SETADV is gradually retarded. Conversely, if the state where knocking does not occur continues, the ignition timing correction amount KNKCS gradually increases and the final ignition timing SETADV is gradually advanced.
Therefore, normally, the final ignition timing SETADV is feedback-controlled near the trace knock point (knocking occurrence limit) corresponding to the fuel used at that time.

Note that the above knocking detection and ignition timing correction amount
The calculation of KNKCS is actually performed individually for each cylinder.

Next, FIG. 5 shows a fuel type determination program. This is executed, for example, at every predetermined crank angle or every predetermined time. First, at step 21, control is performed according to whether or not the type determination flag FHIOC is "1", that is, the current basic ignition timing for high-octane. It is determined whether or not the control is performed according to the regular basic ignition timing. If the control is being executed as high-octane fuel, the routine proceeds to step 22, where the final ignition timing SETADV obtained by correcting the high-octane basic ignition timing TADVH is the regular basic ignition timing TADVR obtained at step 2. Compare. Here, if the final ignition timing SETADV is retarded to the regular basic ignition timing TADVR or less, it is determined that the fuel used is regular fuel, the routine proceeds to step 23, where the type determination flag FHIOC is set to "0". . Therefore, after this, the basic ignition timing TADV is used as the regular basic ignition timing.
TADVR will be selected (steps 3 and 5). Also, if the control is being executed as regular fuel in the determination of step 21, the process proceeds to step 24, and it is obtained by correcting the regular basic ignition timing TADVR. When the final ignition timing S
ETADV is the high ignition basic ignition timing T found in step 1.
Compare with ADVH. Here, if the final ignition timing SETADV is advanced and corrected to be higher than the basic ignition timing TADVH for high-octane, it is determined that the fuel used is high-octane fuel, the routine proceeds to step 25, and the type determination flag FHIOC is set to "1". . Thus, thereafter, the ignition timing is controlled based on the high ignition basic ignition timing TADVH.

When the basic ignition timing map is switched in step 23 or step 25, the routine proceeds to step 26, where the ignition timing correction amount KNKCS is initialized to "0". This prevents a sudden change in the final ignition timing SETADV.

When the knocking control is individually performed for each cylinder as described above, the final ignition timing SETADV is different for each cylinder.
A comparison with the basic ignition timings TADVR and TADVH may be made using the average value of the cylinders.

FIG. 6 shows an example in which the fuel used is switched from high-octane fuel to regular fuel during steady operation of the internal combustion engine 11.
And, it is a diagram schematically showing a change situation of the ignition timing when the fuel is again switched to the high-octane fuel.

In the example of this figure, the high ignition basic ignition timing is initially selected, and as a result of the knocking control described above, the final ignition timing is maintained near the trace knock point of the high octane fuel. When the fuel is switched to the regular fuel at the time point A in the figure, knocking is likely to occur, so the final ignition timing is gradually retarded by the knocking control. Eventually, since the final ignition timing coincides with the regular basic ignition timing, the basic ignition timing map is switched to the regular ignition timing map at that time (time B in the figure).

At this time, as described above, since the ignition timing correction amount KNKCS becomes 0, the final ignition timing before and after the switching becomes smooth and continuous, and no step difference is generated in the engine output or the like.

After that, the final ignition timing is maintained near the trace knock point of the regular fuel, but when the fuel is switched to the high-octane fuel again at the time C in the figure, knocking does not occur, so the final ignition timing is gradually increased by the knocking control. Advance to. Since the final ignition timing eventually coincides with the high ignition basic ignition timing, the basic ignition timing map is switched to the high ignition again at that time (time D). Even during this switching, the ignition timing correction amount KNKCS becomes 0, so that the final ignition timing changes continuously.

By the way, in recent years, as a kind of ignition timing feedback control similar to the knocking control described above, based on the detection of the peak position of the combustion pressure, the ignition timing is controlled to the minimum advance position for obtaining the maximum torque, that is, the MBT point. So-called MBT
Although control is known, the present invention can also use this MBT control and knocking control in combination.
The MBT control itself is disclosed in JP-A-62-96779 and JP-A-58-96779.
Since it is known in Japanese Patent No. 82074, its detailed description is omitted, but if the ignition timing is set so that the crank angle position where the combustion pressure is maximum, that is, the peak position is near ATDC 15 °, the engine generated torque is It is based on the characteristic that it becomes maximum.For example, the combustion pressure is actually detected by the in-cylinder pressure sensor 13 described above, and its peak position is ATDC.
The ignition timing is feedback-controlled so that it comes to around 15 °.

When this MBT control is combined, the advance angle correction is performed by the MBT control when the knocking is not detected, but the advance angle speed at that time can be given larger than the advance angle speed by only the knocking control. Therefore,
As shown in FIG. 7, when the fuel used is switched from the regular fuel to the high-octane fuel, the advance angle correction is promptly performed, and the switching to the high-octane basic ignition timing can be performed with higher responsiveness.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the ignition timing control device for an internal combustion engine according to the present invention, the final ignition timing obtained by correcting either the regular basic ignition timing or the high-octane basic ignition timing is obtained. Compared with the other basic ignition timing, the regular basic ignition timing and the high-octane basic ignition timing are switched. Therefore, when the fuel type changes, this is reliably detected and the basic ignition timing characteristics are switched. It can be performed. Especially, without being restricted by operating conditions,
It is always possible to switch to the basic ignition timing characteristic suitable for the actual octane number of the fuel. Further, there is no step difference in the final ignition timing when the basic ignition timing characteristic is switched. Therefore, the basic ignition timing characteristic can be switched even while the internal combustion engine is operating, and the driveability is not deteriorated due to the change in output.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of an ignition timing control device according to the present invention, and FIG. 2 is an explanatory view showing the structure of an embodiment of the present invention. FIG. 3, FIG. 4, FIG. FIG. 6 is a flow chart showing a control program in the example, FIG. 6 is a characteristic diagram showing a change in ignition timing due to fuel switching, and FIG. 7 is a characteristic diagram showing a change in ignition timing when MBT control is combined. 1 ... Regular basic ignition timing setting means, 2 ... High-octane basic ignition timing setting means, 3 ... selecting means, 4 ...
Ignition timing correction means, 5 ... Knocking detection means, 6 ...
Correction amount calculation means, 7 ... Switching means, 8 ... Ignition device, 9
…… Comparison means

Claims (1)

(57) [Claims] 1. A basic basic ignition timing setting means for setting a regular basic ignition timing according to operating conditions, and a high-octane basic ignition timing setting means for setting a high-octane basic ignition timing according to operating conditions. Selection means for selecting either the regular basic ignition timing or the high-octane basic ignition timing as the ignition timing, and the ignition timing correction for determining the final ignition timing by adding the ignition timing correction amount to one of the selected basic ignition timings. Means, knocking detection means for detecting the occurrence of knocking of the internal combustion engine, and increasing or decreasing the ignition timing correction amount according to the presence or absence of knocking,
Based on this comparison, a correction amount calculation means for initializing the basic ignition timing at regular / high-octane switching, a comparison means for comparing the final ignition timing with the other basic ignition timing not selected at that time, An ignition timing control device for an internal combustion engine, comprising: switching means for giving a switching command to the selecting means when they match.