JP2707319B2 - Knock strength judgment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a knock intensity determination device that can be used for an ignition timing control device for an internal combustion engine.

<Prior Art> In a conventional ignition timing control apparatus for an internal combustion engine, an ignition timing (ignition advance angle) is set based on an engine speed and a load, which are parameters of an engine operating state, and ignition control is performed based on the ignition timing. Is detected based on the signal from the knock sensor, and when the knock is present, the knock is avoided by, for example, correcting the retard at a rate of 1 ° / ignition to avoid the knock. For example, by advancing the angle at a rate of 1 ° / sec, the angle is advanced to the knock limit to improve the output characteristics and the like (Japanese Patent Application Laid-Open No. Sho 62-122262).
No. 73).

<Problems to be Solved by the Invention> However, conventionally, only the presence / absence of knock has been detected, and the determination of the knock intensity has not been performed.

That is, since the retardation speed of the ignition timing at the time of knock generation is constant regardless of the magnitude of the knock, the convergence of the ignition timing is delayed when a strong knock occurs, and in the worst case such as when using poor gasoline, the engine It can lead to damage.

An object of the present invention is to provide a knock strength determination device capable of determining a knock strength in view of such a conventional problem.

<Means for Solving the Problems> For this reason, as shown in FIG. 1, the present invention provides a knock sensor that outputs a signal corresponding to engine vibration, and a knock sensor that responds to knock vibration based on a signal from the knock sensor. A signal processing circuit for obtaining a signal (hereinafter referred to as a "knock signal"); a knock signal vibration frequency detecting means for detecting the number of vibrations of the knock signal; and a first knock intensity evaluation value based on the detected frequency. First knock intensity evaluation value calculating means, knock signal peak value detecting means for detecting a peak value of a knock signal, and second knock intensity evaluation value for calculating a second knock intensity evaluation value based on the detected peak value Strength evaluation value calculation means; and knock strength calculation means for calculating a knock strength based on an average value of the first knock strength evaluation value and the second knock strength evaluation value. A determination device is configured.

<Operation> That is, the number of vibrations of the knock signal and the peak value of the knock signal are detected, and the first and second knock strength evaluation values are calculated based on these as elements related to the knock strength, The knock intensity is calculated based on these average values.

<Example> An example of the present invention will be described below.

Referring to FIG. 2, knock sensor 2 is attached to a cylinder block of engine 1 (six cylinders).

Knock sensor 2 has a piezoelectric element and outputs an electric signal corresponding to vibration of engine 1.

The signal from the knock sensor 2 is processed by the signal processing circuit 3 and converted into a knock signal.

The signal processing circuit 3 includes a band pass filter 3A and a gate circuit 3B. The band-pass filter 3A corresponds to, for example, 7 to 11 corresponding to knock vibration among signals from the knock sensor 2.
The KHz frequency component is passed, and the gate circuit 3B extracts only a signal in a knock angle section, for example, a crank angle section of 10 ° to 57 ° after TDC. As a result, a knock signal is obtained.

The knock signal obtained by the signal processing circuit 3 is converted into a digital signal by the A / D converter 4 and read into the microcomputer 5.

The microcomputer 5 includes a knock intensity determination unit 5A, a cylinder-specific ignition timing correction amount calculation unit 5B, and a cylinder-specific ignition control unit 5C, and finally, the ignition of the ignition plug 7 of each cylinder via the ignition output drive circuit 6. Control behavior.

The knock intensity determination unit 5A basically performs fuzzy inference, and determines the knock intensity to be determined as “no knock”, “small knock”, “medium knock”, “knock large” as shown in FIG. And the approximate state quantities of the knock signal vibration frequency n and the knock signal peak value Vp at these knock intensities are determined in advance, and this is used as an evaluation function (membership function) of the knock intensity.

In determining the knock intensity, first, a knock signal vibration frequency n and a knock signal peak value Vp are detected. Next, the degree of satisfaction of each evaluation function is calculated based on these detected values. Next, the knock intensity is quantified based on the degree of satisfaction of each of the plurality of evaluation functions.

The specific function of knock intensity determination section 5A is shown in the flowchart of FIG.

In step 1 (shown as S1 in the figure, the same applies hereinafter), the number of knock signal vibrations n is detected.

In step 2, the number of vibrations n is evaluated using a predetermined evaluation function of “0”, “small”, “medium”, and “many” with respect to the number of times of knock signal vibration n, and “0”, “low” ",
Assign to “medium” and “many”. In other words, “no knock”, “small knock”, “during knock”, and “large knock” are assigned.

For example, a knock signal the number of vibrations when n is shown n ₁ For example, the allocation value W ₀₁ = 0.0 for "knock Mu", assignment value W ₁₁ = 0.3 for "knock small", assignment value W ₂₁ = 0.7 "under knock" ,
The assignment value of “knock large” is W ₃₁ = 0.0. these
W ₀₁ , W ₁₁ , W ₂₁ , and W ₃₁ correspond to the first knock strength evaluation value.

In step 3, a knock signal peak value Vp is detected.
Here, the peak value Vp = Va−Vb is detected as the difference between the maximum peak value Va and the minimum peak value Vb.

In step 4, the peak value Vp is evaluated using a predetermined evaluation function of "$ 0", "small", "medium", and "large" with respect to the knock signal peak value Vp. "small",
Assign to “medium” and “large”. In other words, “no knock”, “small knock”, “during knock”, and “large knock” are assigned.

For example, when the knock signal peak value Vp is, for example, Vp ₁ shown in the figure, the assigned value W ₀₂ = 0.0 for “no knock”, the assigned value W ₁₂ = 0.7 for “no knock”, and the assigned value W ₂₂ = 0.3 for “knocking” ,
The assignment value of "knock large" is W ₃₂ = 0.0. these
W ₀₂ , W ₁₂ , W ₂₂ , and W ₃₂ correspond to the second knock strength evaluation values.

In step 5, the average of the values assigned to each evaluation function is calculated, and the satisfaction levels W ₀ , W ₁ , W ₂ , and W ₃ of each evaluation function are calculated (see the following equation).

W ₀ = (W ₀₁ + W ₀₂ ) /2=0.0 W ₁ = (W ₁₁ + W ₁₂ ) /2=0.5 W ₂ = (W ₂₁ + W ₂₂ ) /2=0.5 W ₃ = (W ₃₁ + W ₃₂ ) / 2 = 0.0 In step 6, the satisfaction levels W ₀ , W ₁ , W ₂ , W ₃
The knock strength X is quantified as follows. Here, the weights a, b, and a of each of these are set so that the numerical values become larger in the order of “no knock”, “small knock”, “medium knock”, and “large knock”.
c and d are determined in advance (for example, a = 0.0, b = 0.3, c = 0.6, d
= 1.0), and the knock intensity X is calculated from the following equation.

Determination of _{X = aW 0 + bW 1 +} cW 2 + dW 3 = 0.45 or more than the knock intensity becomes possible.

Step 1 corresponds to knock signal vibration frequency detecting means, step 2 corresponds to first knock intensity evaluation value calculating means, step 3 corresponds to knock signal peak value detecting means, Step 4 corresponds to the second knock intensity evaluation value calculating means, and steps 5 and 6 correspond to the knock intensity calculating means.

Next, a cylinder-by-cylinder ignition timing correction amount calculation unit 5B and a cylinder-by-cylinder ignition control unit based on the determination of knock intensity by knock intensity determination unit 5A
Explain the function of 5C.

The cylinder-by-cylinder ignition timing correction amount calculation unit 5B increases or decreases the ignition timing correction amount from the knock intensity for each cylinder.

The specific function of the cylinder-by-cylinder ignition timing correction amount calculation unit 5B is described in the fifth section.
This is shown in the flowchart of the figure.

In step 11, it is determined whether or not knock intensity X is 0,
0 for (no knock), the routine proceeds to step 12, ignition cylinder is to determine What was cylinder, for example, # 1 cylinder predetermined ignition timing correction amount C ₁ for # 1 cylinder in step 13 in the case of Is increased.

Next, in step 14, the retard amount Δ
Referring to the map that defines R, the amount of retardation Δ
Search for R.

Next, in step 15, the ignition cylinder to determine which was What cylinder, for example, in the case of # 1 cylinder ignition timing for # 1 cylinder correction amount C ₁ retrieved retard amount ΔR reduce in step 16.

The cylinder-by-cylinder ignition control unit 5C performs ignition timing control by cylinder.

The specific function of the cylinder-specific ignition control unit 5C is shown in the flowchart of FIG.

In step 21, a map in which the ignition timing (ignition advance angle) ADV is determined according to the engine speed N and the load (for example, the basic fuel injection amount in the electronic control fuel injection device) Tp is referred to.
Search the ignition timing ADV from p.

In step 22, to determine the next ignition cylinder is what cylinder, for example, in the case of # 1 cylinder by adding the ignition timing correction amount C ₁ for # 1 cylinder to the ignition timing ADV in the step 23 ,
Correct the ignition timing ADV. Then, in step 24, an ignition signal is output to the # 1 cylinder at this ignition timing ADV to cause ignition.

<Effects of the Invention> As described above, according to the present invention, the average value of the first knock strength evaluation value based on the number of vibrations of the knock signal and the second knock strength evaluation value based on the peak value of the knock signal is calculated. Since the knock intensity is calculated based on this, it is possible to accurately determine not only the presence or absence of knock but also the knock intensity. Therefore, when used in the ignition timing control device, the convergence of knock control is improved, and the stability of the engine is increased. Further, according to the present invention, the number of vibrations and the peak value of the knock signal are directly detected, and the knock intensity is determined by numerical processing. Therefore, adaptation corresponding to various engines is easy. Can be finely adapted, and the determination accuracy can be further improved.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of a knock intensity determination device according to the present invention, FIG. 2 is a schematic configuration diagram of an ignition timing control device showing one embodiment of the present invention, and FIG. FIG. 4 is a flowchart of knock intensity determination, FIG. 5 is a flowchart of cylinder-by-cylinder ignition timing correction amount calculation, and FIG. 6 is a flowchart of cylinder-by-cylinder ignition control. DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Knock sensor, 3 ... Signal processing circuit, 4 ...
A / D converter, 5: microcomputer, 7: spark plug

Claims (1)

(57) [Claims] 1. A knock sensor for outputting a signal corresponding to engine vibration, and a signal processing circuit for obtaining a signal corresponding to knock vibration from a signal from the knock sensor, based on a signal corresponding to the knock vibration A knock intensity determination device that determines a knock intensity by detecting a knock frequency of a signal corresponding to the knock vibration, and a first knock intensity evaluation value based on the detected frequency. First knock strength evaluation value calculating means for calculating; knock signal peak value detecting means for detecting a peak value of a signal corresponding to the knock vibration; and a second knock strength evaluation value based on the detected peak value. A second knocking strength evaluation value calculating means for calculating; and a knocking strength is calculated based on an average value of the first knocking strength evaluation value and the second knocking strength evaluation value. Knock intensity determining device formed by providing a knock intensity calculating means.