JPS63176664A - Knocking controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To detect knocking with high precision by installing a knocking judgement division changing means which changes the knocking judgement division according to the output of a peak position detecting means in the case when the presence of knocking is judged. CONSTITUTION:The knocking judgement division is changed by a knocking judgement division changing means according to the output of a peak position detecting means when a knocking judging means judges the existence of knocking. In other words, the knocking judgement division is selected or corrected according to the peak position of the knocking wave shape. Therefore, the judgement division is corrected to the optimum position and optimum division width. Therefore, all the knocking wave shapes can be detected under all the operation conditions. Further, the noiseproofness can be improved, and the knocking can be detected with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a knock control device for an internal combustion engine that controls knock control factors such as ignition timing to prevent knocking.

[Conventional technology]

Conventionally, the knocking judgment interval in this type of device has been set in advance to a predetermined crank angle as in Japanese Patent Application Laid-Open No. 58-30477, but due to differences between cylinders, machine differences, changes over time, etc. The accuracy of non-king detection may decrease. Furthermore, as described in Japanese Patent Application Laid-Open No. 58-57072, in a system that changes the ignition timing map by determining the octane number of gasoline, the ignition timing map is significantly different between the map for high octane number and the map for low octane number, so knocking occurs. The location of occurrence is also different, and the above-mentioned phenomenon becomes even more pronounced.

[Problem that the invention seeks to solve]

However, if we try to detect the non-king waveform under all driving conditions, the determination interval becomes quite wide, and the 6th
Since the average value of the non-king detection signal becomes abnormally small, including many parts with small outputs, such as part A in Figure (b), knocking may be incorrectly determined, and the 6th
There is a problem in that the probability of including a noise waveform component like the part B in FIG.

Therefore, the present invention aims to solve the above problems.

[Means for solving problems]

Therefore, as shown in FIG. 1, the present invention includes a non-knocking detection means for detecting knocking occurring in the combustion chamber of an internal combustion engine, and a knocking detection section for setting a knocking judgment section necessary for knocking judgment among the signals from the knocking detection means. determination interval setting means; peak position detection means for detecting the peak position of a signal within the knocking determination interval; averaging means for averaging the signal within the knocking determination interval; and multiplying the signal of the averaging means by a constant. a knocking determination level setting means for creating a knocking determination level by determining the knocking determination level; a comparing means for comparing the knocking determination level with a signal from the knocking detecting means; and determining the presence or absence of knocking based on the output from the comparing means. knocking determination means; knocking determination section changing means for changing the non-king determination section according to the output of the peak position detection means when it is determined that knocking is present as a result of the knocking determination; and an output of the knocking determination means; The present invention provides a knock control device for an internal combustion engine, which includes a control means for controlling knock control factors such as ignition timing accordingly.

[Effect]

Thereby, the knocking determination section is changed by the knocking determination section changing means in accordance with the output of the peak position detecting means when the knocking determination means determines that there is knocking.

〔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 the reference angular position and rotational angular position of the internal combustion engine, 2 is an operating state detection sensor that detects the intake negative pressure of the internal combustion engine, engine rotation speed, etc., and 3 is the internal combustion engine's operating state detection sensor. This is a knocking detector that detects mechanical vibrations caused by knocking. 4 is an engine control unit that calculates the basic ignition timing based on the signals from the position sensor 1 and the driving state detection sensor 2, and retards the basic ignition timing by a predetermined angle when knocking is determined based on the signal from the knocking detector 3. The unit (ECU) is composed of a microcomputer. Reference numeral 5 denotes an ignition device for supplying high voltage to spark plugs disposed in each cylinder of the internal combustion engine in response to an ignition signal from the ECU 4.

FIG. 5 is a flowchart showing the ignition timing map switching based on octane number determination by the microcomputer in the ECU 4, and FIG. 3 is a flowchart showing a method for correcting the knocking determination section by the microcomputer. Figure 4 (A).

(B) is a diagram showing the relative positional relationship between the knocking determination section and the non-king waveform when executing the ignition timing for low octane number (retarded side) and when executing the ignition timing for high octane number (advanced side). In Fig. 4, to(t) is the top dead center (TD) of each cylinder.
The crank angle or time from C) to the start point of the knocking determination section, tp is the crank angle or time from the start point of the non-king determination section to the peak point of the knocking waveform.

The ○ mark is the peak value of the winter peak of the knocking waveform, the * mark is the maximum value of the winter peak value of the knocking waveform, and the x mark is the peak value of the winter peak of the knocking waveform that is undetectable outside the knocking determination area. FIG. 3 is a flowchart showing an embodiment in which the knocking determination interval width is kept constant and the determination interval start timing is modified according to the peak position of the knocking waveform. FIG. 6 is a diagram explaining the problem that occurs when the knocking (judgment interval) is lengthened.
, is a diagram illustrating the maximum tp limit value.

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, there is no particular restriction on the method for determining the octane number. Even with a manual select switch,
Based on the retardation amount based on the knocking determination result (for example, when the retardation amount is controlled at a predetermined value or more for a predetermined period of time, it is determined that the octane number is low, and the retardation amount is controlled at a predetermined value or less. It may be determined that the octane number is high when the time continues for a predetermined period of time).

As a result of the octane number determination, it is determined that the octane number is low.7) If the ignition timing map is determined to be low octane number 7), the ignition timing map for low octane number is switched to (retarded side) in step 24, and if it is determined to be high octane number, the ignition timing map for high octane number is switched to the ignition timing map for high octane number in step 25. (advanced angle side).

In FIG. 3, the knocking determination section is started in step 1 (for example, the timer is set in the TCD to the time equivalent to the crank angle from TDC to the start point of the knocking determination section (
+), and when the timer overflows, knocking determination is started), and the following steps 2 to 6 are performed until a predetermined constant determination period ends in step 7.

First, in step 2, the peak value of the winter 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 the winter peak and the zero-cross conversion value of the peak value from the determination interval are detected. Since the zero-crossing cycle is a constant value, if you know what number of zero-crossing conversion values it is, you can find the time tp from the start of the knocking judgment section to the maximum position of the winter peak value of the knocking detection signal (see FIG. 4). The peak position detected here is to
(i) (i is the cylinder number). In step 4, each peak value of the winter mountain is rounded to create an average value of the knocking detection signal. In step 5, the average value of the knocking detection signal is multiplied by a constant to create a knocking determination level, and the average value at this time is the previous average value for that cylinder.

In step 6, the knocking determination level is compared with each peak value of the winter mountains, and those exceeding the determination level are stored in Kp as knock pulses. When it is determined in step 7 that the determination period has ended, in step 8 a 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 process proceeds to step 9, and a retard amount is calculated according to the knock pulse Kp. Although not specifically stated here, the type that determines the octane number based on the amount of retardation performs controls such as switching the ignition timing map and switching the control boost pressure according to the results. (in combination with Figure 5). If the knock pulse Kp is less than 1 in step 8, it is determined that there is no knock, and the process directly proceeds to step 14, ignition timing control. If tp is smaller than the minimum tp limit value a in step 10 (if the knocking occurrence position is earlier than the allowable value), in step 13 the knocking determination section start time to(i) is set to a
To advance by -tp, subtract a-tp from t o (i) and create a new t
o(+), and the process proceeds to step 14, ignition timing control. Also, if tp is 8 or more in step 10, proceed to step 11, compare it with the maximum tp limit value, and if tp is larger than b (if the knocking occurrence position is later than the allowable value)
In step 12, to delay to(i) by b-tp, the sum of to(i) and b-tp is newly set as to(i), and the process proceeds to step 14, ignition timing control. In addition, if tp is less than or equal to b in step 11, it is determined that the knocking judgment section is appropriate, and step 14 is performed.
Proceed to ignition timing control. Here, the minimum tp limit value a2 the maximum tp limit value are the knocking waveforms of each engine under all operating conditions, and the one with the longest portions a' and b' in FIG. a'.

It is preferable that b=b'.

In addition, in this embodiment, a method was shown in which the width of the knocking judgment section is kept constant and the start time of the judgment section is corrected according to the peak position of the knocking waveform. Alternatively, it is also possible to have a map of the start time of the determination section and the end time of the determination section, and to switch it according to the peak position of the knocking waveform.

Further, control for switching or modifying the knocking determination section according to the peak position of the knocking waveform may be performed only under specific operating conditions of the internal combustion engine.

〔Effect of the invention〕

As described above, in the present invention, by switching or modifying the knocking judgment section according to the peak position of the knocking waveform, the judgment section is corrected to the optimum position and optimum section width. This has the excellent effect of making it possible to detect knocking, improve noise resistance, and enable highly accurate knocking detection.

[Brief explanation of the drawing]

1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the device of the present invention, FIGS. 3 and 5 are flowcharts for explaining the operation of the device U shown in FIG. 2, and FIG. Figures (A), (B), and Figure 7 are waveform diagrams for explaining the operation of the device shown in Figure 2, and Figure 6 is a waveform diagram for explaining the 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] knocking detection means for detecting knocking occurring in a combustion chamber of an internal combustion engine; knocking determination section setting means for setting a knocking determination section necessary for knocking determination out of a signal from the knocking detection means; and within the knocking determination section. peak position detection means for detecting the peak position of the signal; averaging means for averaging the signals within the knocking determination section; and a knocking determination level for creating a knocking determination level by multiplying the signal of the averaging means by a constant. a setting means, a comparison means for comparing the knocking determination level with a signal from the knocking detection means, a knocking determination means for determining the presence or absence of knocking based on the output from the comparing means, a result of the knocking determination; knocking determination section changing means for changing the knocking determination section according to the output of the peak position detecting means when it is determined that there is knocking; and controlling knock control factors such as ignition timing according to the output of the knocking determining means. A knocking control device for an internal combustion engine, comprising a control means for controlling.