JPH0258470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ignition timing control device for an internal combustion engine. It is well known that the octane number of gasoline has a strong correlation with knock resistance in internal combustion engines. In other words, the higher the octane number, the more difficult it is to knock. FIG. 1 shows the ignition timing-output shaft torque characteristics of an internal combustion engine using commercially available regular gasoline and premium gasoline (which has a higher octane number than regular gasoline). Point A is the knock limit point when regular gasoline is used, and point B is the knock limit point when premium gasoline is used. Knock occurs when the ignition timing is advanced beyond the knock limit point. According to FIG. 1, when premium gasoline is used, the ignition timing can be advanced to point B, so it is possible to improve the output shaft torque compared to when regular gasoline is used.

In an internal combustion engine with such characteristics, when regular gasoline and premium gasoline are mixed or used interchangeably, engine output can be improved by advancing the ignition timing according to the mixing ratio of regular gasoline and premium gasoline. It becomes possible to do so.

[Prior art]

By the way, in conventional ignition timing control devices, ignition timing characteristics are set only for a predetermined gasoline, for example regular gasoline.
When using premium gasoline mixed or converted, engine output cannot be expected to improve as is, and the ignition timing had to be reset to the advanced side by some method. In particular, when using mixed gasoline, there is a knock limit point between point A and point B in Figure 1 depending on the mixing ratio of regular gasoline and premium gasoline, and the possible advance limit changes, so the ignition timing must be reset. It was not easy.

[Summary of the invention]

Therefore, the present invention has been made in view of the above points, and uses a knock sensor to detect the occurrence of a knock, and based on the detected value, changes the ignition timing based on the mixture ratio of regular gasoline and premium gasoline in use. By determining the amount and setting the ignition timing to the advance or retard side accordingly, the standard ignition timing can be adjusted to the optimal position even when regular gasoline and premium gasoline are mixed, and the ignition timing can be further improved. By setting the amount of displacement of the timing to the retarded side at the time of initial operation, the purpose is to operate the engine from the safe side without inducing severe knocking at the beginning of the displacement operation.

[Embodiments of the invention]

FIG. 2 illustrates an embodiment of the invention. In FIG. 2, reference numeral 1 denotes a knock sensor that is attached to the engine and detects a knock in the engine. Reference numeral 2 designates a knock discriminating unit that determines whether or not a knock has occurred from the output signal of the knock sensor 1, and a band pass filter 2
1, a noise level detector 22, and a comparator 23. The input of the bandpass filter 21 is connected to the knock sensor 1, and the output is connected to the comparator 23.
and a first comparison input of the noise level detector 22 . The output of the noise level detector 22 is then connected to a second comparison input of the comparator 23. 3 is an ignition timing displacement determination unit, which includes a retard control voltage generator 31, a comparator 32, a comparator 33,
It is composed of an AND gate 34, an AND gate 35, and an integrator 36. Retard control voltage generator 3
The input of 1 is connected to the output of comparator 23. Comparators 32 and 33 convert the output voltage of the retard control voltage generator 31 to a predetermined voltage level V _{1 .}
and V ₂ , the comparison outputs of which are connected to one input of an AND gate 34 and an AND gate 35, respectively. The other inputs of the AND gate 34 and the AND gate 35 are both connected to the output of the operating region determiner 4. The integrator 36 has two inputs, a lead angle input and a retard angle input, and the output of the AND gate 34 is connected to the lead angle input, and the output of the AND gate 35 is connected to the retard input. Integrator 36
An initialization circuit for initializing the output voltage of the integrator 36 is also connected to the integrator 36 . The operating range determiner 4 inputs the output voltages of the pressure sensor 10 and the frequency-voltage (F/V) converter 11. The pressure sensor 10 detects the intake manifold pressure of the engine and outputs a voltage according to the operating load of the engine. The F/V converter 11 receives an ignition signal output from an ignition timing phase shifter 6, which will be described later, and converts the frequency of the ignition signal into a voltage value, thereby outputting a voltage corresponding to the engine speed. The ignition timing phase shifter 6 shifts the phase of the reference ignition timing signal output from the reference ignition timing signal generator 7 according to the output voltage of the retard control voltage generator 31 and the output voltage of the integrator 36. An ignition signal indicating the ignition timing is output to the ignition device 8. The ignition device 8 uses an ignition coil 9 to generate a high voltage necessary for igniting the engine.

Next, the operation of each part will be explained. FIG. 3 shows the operation of each part of the knock discriminating section 2. The knock sensor 1 is a generally well-known vibration acceleration sensor,
It is attached to the cylinder block of an engine, converts the mechanical vibration of the engine into an electrical signal, and outputs a vibration wave signal as shown in FIG. 3a. The bandpass filter 21 passes only the frequency component peculiar to the knock from the output signal of the knock sensor 1, suppresses noise components other than the knock, and outputs a signal with a good S/N ratio as shown in A of Fig. 3b. . The noise level detector 22 can be composed of, for example, a half-wave rectifier circuit, an averaging circuit, an amplifier circuit, etc., and converts the output signal of the bandpass filter 2 (a in FIG. 3b) into a direct current by half-wave rectifying and averaging. It is converted to a voltage level and amplified at a predetermined amplification degree, and as shown in FIG. 3B, the level is higher than the noise component of the output signal of the bandpass filter 21 (FIG. 3B, A), but lower than the knock component. outputs a DC voltage of The comparator 23 compares the output signal of the bandpass filter 21 (a in FIG. 3b) with the output signal of the noise level detector 22 (b in FIG. 3b), and if no knock occurs (FIG. 3c). Since the output signal of the band pass filter 21 (a in Figure 3b) does not exceed the output signal of the noise level detector 22 (b in Figure 3b), nothing is output, and a knock occurs. (Figure 3, Part D)
Since the output signal of the band pass filter 21 (A in FIG. 3B) exceeds the output signal of the noise level detector 22 (B in FIG. 3B), a pulse train is output as shown in FIG. 3C. Therefore, the occurrence of a knock can be determined by the presence or absence of a pulse train (FIG. 3c) from the output of the comparator 23.

FIG. 4 shows the operation of the ignition timing displacement determination section 3. The retard control voltage generator 3 can be configured, for example, by an integrating circuit, and when the comparator 23 outputs a pulse train as shown in FIG. 4a, it integrates the pulse train and outputs it as shown in FIG. 4b. Increase voltage. Further, when the pulse train is not output from the comparator 23, the output voltage of the retard control voltage generator 31 gradually decreases at a predetermined speed. That is, the retard control voltage generator 31 generates in real time a retard control voltage that retards the ignition timing to the knock limit point. Then, the ignition timing phase shifter 6 inputs the retard control voltage and retards the ignition timing, thereby immediately suppressing the occurrence of knock.

On the other hand, the comparators 32 and 33 compare the retard control voltages output from the retard control voltage generator 31 at voltage levels _V1 and _V2 , respectively. V ₁
The relationship between V 2 and V ₂ is, for example, the maximum value of the retard control voltage V _MAX
and the minimum value V _MIN is set as V _MIN < V ₁ < V ₂ < V _MAX . Then, the comparator 32 detects that the retard control voltage is
If V is smaller than ₁ , a high level is output; if it is larger, a low level is output. The output operation of the comparator 32 is shown in FIG. 4c. Further, the comparator 33 outputs a high level if the retard control voltage is greater than _V2 ,
If it is small, a low level is output. The output operation of the comparator 33 is shown in FIG. 4d. When the high-level signal from the comparator 32 passes through the AND gate 34 and is input to the advance input of the integrator 36, the integrator 36 gradually lowers the output voltage as shown in FIG. Displace it to the corner side. When the high level signal from the comparator 33 passes through the AND gate 35 and is input to the retard input of the integrator 36, the output voltage is gradually increased and shifted to the retard side as shown in FIG. 4g. Further, when both the advance angle input and the retard angle input of the integrator 36 are at a low level, the output voltage of the integrator 36 is held. Further, the operating range determiner 4 receives engine operating load information from the pressure sensor 10,
Engine rotation information is obtained from the converter 11, and an operating range map based on load and rotation speed is formed. and,
The operating range in which the output voltage of the integrator 36 can be advanced or retarded is set in advance on the above map, and if the operating state of the engine is within the set operating range, the operating range is determined. The device 4 outputs a high level signal as shown in FIG. 4e, and outputs a low level signal in other operating regions. And gate 34 and gate 3
Reference numeral 5 controls the passage of the output signals of the comparators 32 and 33 to the integrator 36 based on the output signal of the operating range determiner 4. Therefore, in the ignition timing displacement determination section 3, the integrator 36 determines that the retard control voltage output from the retard control voltage generator 31 is smaller than _V1 and the engine is in the predetermined operating range, as shown in FIG. 4g. If the retard control voltage is greater than V ₂ and the engine is within a predetermined operating range, the output voltage is shifted to the retard side, and the retard control voltage is The output voltage is held when the angle control voltage is between V ₁ and V ₂ or when the engine is outside the predetermined operating range.

For example, when starting the engine, the initialization circuit 5 is activated as shown in FIG.
A high-level pulse is generated as shown in Fig. 4g, and while this pulse is being output, the output voltage of the integrator 36 is
Fix it at a predetermined level as shown in .

Then, when the pulse output disappears, the above-described operation for determining the reference ignition timing displacement amount from the fixed predetermined level, that is, the predetermined reference ignition timing displacement point, is performed. The initial setting level of the integrator 36 is set on the retard side in terms of the overall displacement amount. If the output voltage of the integrator 36 is not initialized and it happens to operate from the advance side, when regular gasoline with a low octane number is used, the initial reference ignition timing will be lower than the knock limit point when using regular gasoline. Since the angle is set far ahead, it can cause severe knocking, potentially damaging the engine. This severe knock occurrence is immediately suppressed by the retard voltage output from the retard control voltage generator 31 described above, but due to the retard angle responsiveness of the retard control voltage generator 31, the retard angle is controlled to the knock limit point. A severe knock occurs during the process.

However, when the output voltage of the integrator 36 is initially set to the retarded side, the initial reference ignition timing is not set to the advanced side by a value greater than the knock limit point, which induces the severe knock described above. Never.

Regarding the initialization circuit 5, a method of generating a pulse when starting the engine has been shown, but it is also possible to detect the opening/closing of the gas tank inlet lid during gasoline refueling, or to detect a change in the gasoline remaining gauge. By doing so, it may be possible to detect that gasoline has been newly injected and generate a pulse.
Further, in this case, a backup power source may be added so that the output voltage of the integrator 36 is stored and retained even when the engine is stopped.

〔Effect of the invention〕

As explained above, according to the present invention, when regular gasoline and premium gasoline are mixed and used, a knock sensor is used to detect the occurrence of a knock, and the reference ignition timing is advanced or retarded based on the detected value. By initially setting the displacement amount to the retarded side during the initial displacement operation, there is an effect that the reference ignition timing can be optimally adjusted without inducing severe knocking during the initial operation.

[Brief explanation of the drawing]

FIG. 1 is an output shaft torque characteristic diagram of the engine, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are explanatory diagrams of the operation of the embodiment of FIG.
In the figure, 1 is a knock sensor, 2 is a knock discriminator, 3 is an ignition timing displacement determining unit, 4 is an operating range determiner, and 5 is a knock sensor.
1 is an initialization circuit, 6 is an ignition timing phase shifter, 7 is a reference ignition timing signal generator, 8 is an ignition device, 9 is an ignition coil, 10 is a pressure sensor, and 11 is an F/V converter.

Claims (1)

[Claims] 1. A knock sensor that detects a knock in an internal combustion engine;
Knock determining means determines whether or not a knock has occurred based on the output of the knock sensor; displacement determining means determines the displacement amount of the reference ignition timing of the engine from the output of the knock determining means; An ignition timing control device for an internal combustion engine, comprising ignition timing shifting means for displacing ignition timing, and means for initializing the displacement amount of the displacement amount determining means to a predetermined value on the retard side.