JPH0726603B2 - Knotting control device for internal combustion engine - Google Patents

Description

The present invention relates to a knocking control device for an internal combustion engine, which controls a knocking control factor such as ignition timing so that knocking does not occur.

[Conventional technology]

Conventionally, the knocking determination section in this type is disclosed in
Although the crank angle is set to a predetermined crank angle in advance as in Japanese Patent Laid-Open No. 58-30477, the knocking waveform may deviate from the determination section and the knocking detection accuracy may be deteriorated due to a difference between cylinders, a machine difference, and a change over time. In addition, JP-A-58-57072
As described in Japanese Patent Publication, in the case of determining the octane number of gasoline and switching the ignition timing map, since the ignition timing is greatly different between the high octane number map and the low octane number map, the knocking occurrence position is also different, and the above-mentioned phenomenon Becomes even more noticeable.

[Problems to be solved by the invention]

However, when trying to detect a knocking waveform in all driving conditions, the judgment section becomes considerably wide, and
Since the average value of the knocking detection signal becomes abnormally small by including many small output portions such as the portion A of FIG. 6B, the knocking is erroneously determined, or FIG. 6C. There is a problem in that the probability of including a knocking waveform component such as B part of No. 2 increases, the noise resistance deteriorates, and the knocking detection accuracy decreases.

Then, this invention aims at solving the said problem.

[Means for solving problems]

Therefore, according to the present invention, as shown in FIG. 1, a knocking detecting means for detecting knocking occurring in a combustion chamber of an internal combustion engine, and a knocking determining section for setting a knocking determination section necessary for knocking determination among signals from the knocking detecting means. Judgment section setting means, peak position detection means for detecting a peak position of a signal within the knocking judgment section, knocking judgment level setting means for creating a knocking judgment level based on the signal from the knocking detection means, and the knocking judgment Comparing means for comparing the level with a signal from the knocking detecting means in the knocking determining section; knocking determining means for determining the presence or absence of knocking on the basis of the output from the comparing means; When the peak position is detected, it is detected by the peak position detecting means. A knocking determination section changing means for changing the knocking determination section according to a comparison result of the phase relationship between the peak position and the knocking determination section, and controlling a knock control factor such as ignition timing according to the output of the knocking determination section. There is provided a knocking control device for an internal combustion engine, comprising:

[Action]

As a result, the knocking determination section changing unit changes the knocking determination section according to the comparison result of the phase relationship between the peak position detected by the peak position detecting section and the knocking determination section when the knocking determination section determines that knocking is present. To do.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings. In FIG. 2, 1 is a position sensor that detects a reference angular position and a rotational angular position of the internal combustion engine, 2 is an operating state detection sensor that detects an intake negative pressure of the internal combustion engine, engine speed, and the like, and 3 is an internal combustion engine. This is a knocking detector that detects mechanical vibration caused by knocking. An engine control 4 calculates the basic ignition timing based on the signals from the position sensor 1 and the operating state detection sensor 2 and delays the basic ignition timing by a predetermined angle when it is determined that knocking occurs in response to the signal from the knocking detector 3. A unit (ECU) that is composed of a microcomputer. Reference numeral 5 is an ignition device for supplying a high voltage to an ignition plug arranged in each cylinder of the internal combustion engine in response to an ignition signal from the ECU 4.

FIG. 5 is a flow chart showing the ignition timing map switching by the octane number discrimination in the microcomputer in the ECU 4, and FIG. 3 is a flow chart showing the method of correcting the knocking determination section in the microcomputer. FIGS. 4 (A) and 4 (B) show the relative positional relationship between the knocking determination section and the knocking waveform when the low octane number ignition timing (retard side) is executed and the high octane number ignition timing (advance side) is executed. It is a figure. In FIG. 4, to (i) is the crank angle or time from the top dead center (TDC) of each cylinder to the knocking determination section start point, and tp is the crank angle or time from the knocking determination section start point to the peak point of the knocking waveform. Is. ○ indicates the peak value of each peak of the knocking waveform, ● indicates the maximum peak value of each peak of the knocking waveform,
The mark X indicates the peak value of each peak of the undetectable knocking waveform outside the knocking determination section. FIG. 3 is a flowchart showing an embodiment in which the width of the knocking determination section is fixed and the start time of the determination section is corrected according to the peak position of the knocking waveform. FIG. 6 is a diagram illustrating a problem that occurs when the knocking determination section is lengthened. FIG. 7 is a diagram for explaining the minimum tp limit value a and the maximum tp limit value b.

In FIG. 5, step 21 initializes each control parameter, step 22 reads the operating parameters of the engine from each sensor 1 to 3, and step 23 determines the octane number. Here, the method for determining the octane number is not particularly limited. Even with the manual select switch, the delay amount based on the knocking determination result (for example, when the time when the retard amount is controlled at the predetermined value or more continues for the predetermined period, the low octane number is determined, May be determined to be a high octane number when the control time is less than or equal to a predetermined value for a predetermined period.

If it is determined that the octane number is low as a result of the octane number determination, the ignition timing map for low octane number is switched to the ignition timing map (retard side) in step 24. Side).

In FIG. 3, the knocking determination section is started in step 1 (for example, in TCD, a timer is set to the crank angle equivalent time to (i) from TDC to the knocking determination section start point, and when the timer overflows, the knocking determination is performed. Start), and the control of the following steps 2 to 6 is performed until the predetermined determination section determined in step 7 ends. First, in step 2, the peak value of each peak of the knocking detection signal waveform is subjected to zero-cross AD conversion, and in step 3, the maximum value of the peak value of each peak and the number of zero-cross conversion values of the peak value from the determination section are detected. The zero-cross cycle is a constant value, so if you know how many times the zero-cross conversion value is,
The time tp (see FIG. 4) from the start timing of the knocking determination section to the maximum value position of the peak value of each peak of the knocking detection signal can be known. The peak position detected here is to
It is stored in (i) (i is the cylinder number). In step 4, each peak value of each mountain is smoothed to create an average value of knocking detection signals. In step 5, the average value of the knocking detection signals is multiplied by a constant to create a knocking determination level.
The average value at this time is the previous average value of the cylinder. In step 6, the knocking judgment level is compared with each peak value of each mountain, and the value exceeding the judgment level is set as a knock pulse Kp.
Remember. When it is determined in step 7 that the determination section has ended, in step 8, knock determination is performed based on the presence or absence of the knock pulse Kp. When the knock pulse Kp is 2 or more, the routine proceeds to step 9, where the retard amount is calculated according to the knock pulse Kp. Here, although not particularly described, in the case where the octane number is determined based on the retard angle amount, the octane number is determined and the ignition timing map is switched and the control boost pressure is controlled according to the result. Perform (combined with FIG. 5). Further, when the knock pulse Kp is 1 or less in step 8, it is judged that there is no knock and the routine proceeds to the ignition timing control of step 14 as it is. In step 10
When tp is smaller than the minimum tp limit value a (when the knocking occurrence position is earlier than the allowable value), in step 13, the knocking determination section start time to (i) is advanced from a (i) to a The value obtained by subtracting is newly set to (i), and the ignition timing control of step 14 is proceeded to. Also step
When tp is 10 or more at 10 and proceeds to step 11, and when compared with the maximum tp limit value b, when tp is larger than b (when the knocking occurrence position is later than the allowable value), at step 12 to (i)
Is delayed by b-tp, the addition of b-tp to to (i) is newly designated as to (i), and the ignition timing control of step 14 is proceeded to. If tp is equal to or less than b in step 11, it is determined that the knocking determination section is appropriate, and the process directly proceeds to ignition timing control in step 14. Here, for the minimum tp limit value a and the maximum tp limit value b, the knocking waveforms are investigated under all operating conditions in each engine, and the one with the longest part in FIG. It is preferable that = a 'and b = b'.

In the present embodiment, the method for correcting the determination section start time in accordance with the peak position of the knocking waveform while keeping the knocking determination section width constant is shown, but the determination section start time and the determination section width are provided as a map, Alternatively, the determination section start timing and the determination section end timing may be held as a map and switched according to the peak position of the knocking waveform. Further, the control for switching or correcting the knocking determination section according to the peak position of the knocking waveform may be performed only under the specific operating condition of the internal combustion engine.

〔The invention's effect〕

As described above, in the present invention, the peak position of the knocking waveform when knocking occurs by switching or modifying the knocking determination section according to the comparison result of the phase relationship between the peak position of the knocking waveform when knocking occurs and the knocking determination section. The knocking judgment section is corrected to the optimum position and the optimum section width according to the above, so that all knocking waveforms can be detected under all operating conditions, noise resistance is also improved, and highly accurate knocking detection becomes possible. There is an excellent effect.

[Brief description of drawings]

1 is a block diagram showing the claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the device of the present invention, and FIGS. 3 and 5 are flow charts for explaining the operation of the ECU shown in FIG.
7A and 7B and FIG. 7 are waveform charts for explaining the operation of the apparatus shown in FIG. 2, and FIG. 6 is a waveform chart for explaining problems that occur when the knocking determination section is lengthened. . 1 …… Position sensor, 2 …… Operating state detection sensor, 3 …… Knocking detector, 4 …… ECU, 5 …… Ignition device.

Claims (1)

[Claims] 1. Knocking detection means for detecting knocking occurring in a combustion chamber of an internal combustion engine, and knocking determination section setting means for setting a knocking determination section necessary for knocking determination among signals from the knocking detection means.
Peak position detection means for detecting a peak position of a signal within the knocking determination section, knocking determination level setting means for creating a knocking determination level based on the signal from the knocking detection means, the knocking determination level and the knocking determination section. Comparing means for comparing the signal from the knocking detecting means in the inside, knocking judging means for judging the presence or absence of knocking based on the output from the comparing means, and the result of the knocking judgment, when it is judged that there is knocking Of knocking determination section changing means for changing the knocking determination section according to the comparison result of the phase relationship between the peak position detected by the peak position detecting means and the knocking determination section, and according to the output of the knocking determination means. Internal combustion comprising control means for controlling knock control factors such as ignition timing Seki for knocking control device.