JPS6248063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling ignition timing while detecting knocking in an internal combustion engine.

Conventionally, when designing internal combustion engines installed in automobiles, etc., various considerations have been made from the perspective of improving performance. The so-called MBT (Minimum advance for Best
A negative pressure advance mechanism and a centrifugal advance mechanism are used to obtain ignition timing characteristics close to those of Torque.

However, in the relatively low speed range of a normal spark-ignition internal combustion engine, the ignition timing limit at which knocking occurs (varies depending on the type of engine, fuel octane rating, etc.) is on the later side than MBT. Therefore, if the ignition timing is set to MBT, knocking will occur.

Therefore, in a relatively low speed range, the ignition timing should be set to M as much as possible without knocking.
In order to get closer to BT, it is best to set the ignition timing to the above-mentioned limit ignition timing, but in reality, due to the effects of changes in the engine over time and variations in the octane number of the fuel, etc. The reality is that the ignition timing has to be set later than the limit ignition timing, resulting in a decrease in fuel efficiency and output performance. The rate of decrease in fuel efficiency and output performance caused by delaying the ignition timing is particularly large in turbocharged engines and high compression ratio engines, which have recently attracted attention as a means of improving fuel efficiency and output performance. This has become a major problem.

Moreover, even if the ignition timing is set later than the above-mentioned limit ignition timing with a margin, knocking may occur depending on the driving conditions of the vehicle, the operating conditions of the engine, and the environmental conditions. The reality is that it is not possible to completely avoid knot kings.

Further, delaying the ignition timing to prevent knocking in such a case would result in a significant decrease in the fuel efficiency and output performance of the engine, which would be impractical.

Therefore, the ignition timing is usually controlled by a negative pressure advance mechanism or a centrifugal advance mechanism that has the same ignition timing characteristics as before or slightly advanced ignition timing characteristics, and only when knocking occurs, For example, a device that avoids knocking by retarding the ignition timing from the ignition timing of the
This was previously proposed in the specification of No. 4002155.

The ignition timing control device disclosed in this US patent specification performs sampling to determine the presence or absence of knocking at every regular cycle, and retards the ignition timing by a fixed retard amount each time it is determined that knocking exists during sampling. Each time it is determined that there is no knocking during sampling, the ignition timing is advanced by a fixed amount to the normal advance angle. but,
In this configuration, since the fixed amount of retard and advance angle control is performed only at the time of sampling, the start-up of the control is slow and responsiveness is poor. Furthermore, since the amount of retardation is constant regardless of the degree of knocking (occurrence frequency), it cannot be said that this amount of retardation necessarily corresponds to the required amount, and knocking will disappear only after a considerable number of samplings. This also causes the inconvenience of not being able to obtain a similar amount of retardation, and in this respect as well, poor responsiveness is unavoidable.

In view of the above, the present invention has developed a new ignition timing control device to replace this device. Specifically, each time a knocking judgment signal is input, the calculated value immediately changes to the retard direction by an amount equivalent to a predetermined crank angle. At the same time, while the knocking determination signal is not input, the calculated value is continuously returned in the advance direction at a rate slower than the change in the retard direction of the calculated value with respect to time. The object of the present invention is to provide an ignition timing control device which is provided with a calculation unit that performs calculations, generates a retard signal with a pulse width corresponding to the magnitude of the calculation value, and is configured to retard the ignition timing by the amount of this pulse width. .

Hereinafter, the present invention will be explained in detail based on illustrated embodiments,
Mention its effects.

FIG. 1 is a block diagram showing the ignition timing control device of the present invention together with a knocking detection device.
0, a smoothing section 200, a comparison section 300, and a knocking intensity detection section 400, and upon receiving the knocking judgment signal from this knocking detection device, a calculation section 500, a frequency/voltage conversion section 600, and a uniform advance angle control are performed. The ignition timing control device of the present invention comprising section 700 outputs a corrected ignition timing signal to ignition coil 3 via ignition coil drive section 2 . Note that 4 is an ignition command signal input section to which an ignition command signal of a normal advance angle is input from a breaker point of a distributor driven by the engine, for example.

The vibration sensor 1 is attached to a spark ignition engine,
A piezoelectric element is used to convert pressure fluctuations in the combustion chamber into electrical signals, and this is converted into a knocking vibration frequency (e.g.
The resonance point is assumed to be near 6.5 to 8.5KHz).
As the vibration sensor 1, instead of this piezoelectric element, a resonance type sensor having a similar resonance point is used, or a sensor that intercepts the sound emitted from the engine and converts only the frequency component corresponding to knocking into an electric signal is used. or any other similar sensor can be used.

The electric signal of the knocking-equivalent frequency component obtained in this way still contains a low frequency component that becomes an interfering signal, and after this is removed by the sensor processing section 100, the signal from which the interfering signal has been removed is sent to the sensor. The processing unit 100 amplifies and rectifies the signal. Although this rectification will be described as half-wave rectification in the example described below, it goes without saying that full-wave rectification may also be used. It goes without saying that the vibration sensor 1 may convert all frequency components into electrical signals, and the signals may be passed through a bandpass filter to obtain electrical signals with frequency components corresponding to knocking.

The smoothing section 200 smoothes the rectified signal, and inputs the smoothed level together with the signal from the sensor processing section 100 to the comparison section 300, which compares the two. The knocking intensity detection section 400 integrates the comparison output signal obtained by the comparison section 300, and compares this integrated value with a reference level every predetermined crank angle width, for example, every ignition cycle. When the integral value exceeds the reference level, the knocking intensity detection section 400 determines knocking and outputs the signal.

When the knocking detection device outputs the knocking determination signal from the knocking intensity detecting section 400 as described above, this signal triggers the calculating section 500. Thus, this calculation section performs calculations to retard the ignition timing by a predetermined amount each time a trigger signal is input, and to generate a signal for advancing the ignition timing toward normal ignition timing using a predetermined function while no trigger signal is input.

On the other hand, in the frequency/voltage conversion section 600, the input section 4
The ignition command signal from the input unit 500 is converted into a voltage, and this, the above-mentioned signal from the calculation unit 500, and the ignition command signal from the input unit 4 are input to the uniform advance angle control unit 700. The control unit 700 delays the normal ignition timing according to each input signal, outputs the corrected ignition timing signal to the ignition coil drive unit 2, and then delays the ignition coil 3 by a predetermined angle from the normal one.
can be driven.

Next, details of each of the above parts will be explained.

FIG. 2 shows an example of the configuration of the sensor processing section 100,
A filter circuit consisting of resistors R101, R102, R103 and a capacitor C101 removes low frequency components that become noise signals from the electrical signal of knocking-equivalent frequency components from the vibration sensor 1. The electrical signal at the knocking-equivalent frequency (for example, 6.5 to 8.5 KHz) from which the interference signal has been removed is, for example, the one shown at 5 in Figure 6, which generates large signals that are considered to be knocking at times A and B. ing.

However, the signal from the vibration sensor 1 also includes a vibration component that steadily occurs as the engine burns, and the amplitude of this vibration component varies depending on the engine operating state (engine speed, load state, etc.). ), there is a problem in comparing the signal 5 with a certain reference level and determining that vibration components exceeding this level are due to knocking. This is because vibration components exceeding the reference level may be caused by engine operating conditions. In this sense, the reference level with which the signal 5 is compared needs to be varied depending on the operating state, and therefore for this purpose the signal 5 is adjusted as described below.
Detects knocking vibration components.

That is, the signal 5 that has passed through the filter circuit
is an operational amplifier OP101 having resistors R104, R105, R106 and resistors R108, R10.
9 and an operational amplifier OP102 having R110 connected through a diode D101 and a resistor R107, where it is amplified in a predetermined manner. At this time, operational amplifiers OP101 and OP10
Since a signal is input to the positive side of the terminal 2, an operating waveform obtained by half-wave rectification of the signal is outputted to the terminal 10, as shown with the same reference numerals as this terminal in FIG.

FIG. 3 shows an example of the configuration of the smoothing section 200, in which the operating waveform from the terminal 10 is connected to the resistor R201 and the capacitor C2.
01, and the smoothed value is amplified to a predetermined level by an amplifier OP201 having resistors R202 and R203, and a smoothed level shown by the same symbol as this terminal in FIG. 6 is output from terminal 20. do.

FIG. 4 shows an example of the configuration of the comparing section 300, in which the operating waveforms and smoothing levels from the terminals 10 and 20 are compared with each other. For this purpose, an operational amplifier OP301 having a resistor R302 is provided, the smoothing level from the terminal 20 is inputted to its positive input terminal via the resistor R301, and the operating waveform from the terminal 10 is inputted to its negative input terminal. Thus, both these signals are compared by operational amplifier OP301,
A comparison output signal (pulse signal) indicated by the same reference numeral as this terminal in FIG. 6 is output from the terminal 30. This pulse signal is normally at a high level and goes to a low level while the signal from terminal 10 exceeds the smooth level signal from terminal 20 (this time reflects the magnitude of the signal from terminal 10). shall be. Note that if all the negative pulses of the pulse signal output from the terminal 30 are determined to be knocking, it will be an erroneous determination because the signal from the vibration sensor 1 contains various pseudo-knocking vibrations including ignition noise. Therefore, in the illustrated example, the integrated value of the negative polarity pulse is compared with a reference level every predetermined crank angle width, for example, every ignition cycle, using a circuit described below.

For this purpose, the knocking strength detection section 400 is installed as the fifth
The configuration shown in the figure is used. A pulse signal generated at terminal 30, for example a pulse signal shown with the same reference numeral as this terminal in FIG.
401, and if the switch S401 is open at this time, the negative polarity pulse of the above pulse signal is integrated, the integrated value is added, and a step-like signal is output from the terminal 41, which is shown with the same reference numeral as this terminal in FIG. The operating waveform is output. On the other hand, an ignition command signal is outputted from terminal 4, which is shown with the same reference numeral as this terminal in FIG. A differential pulse signal indicated by the same symbol, that is, a signal having a positive polarity pulse of a constant width is output at every rising instant of the ignition command signal 4. This signal closes switch S401 every time a positive pulse is issued, that is, every time an ignition command is issued, capacitor C401 is shorted and integrator OP401 is reset. Therefore, the signal outputted to terminal 41 returns to the specified low level at every ignition instant, as indicated by the same reference numerals as this terminal in FIG. It becomes a staircase waveform obtained by integrating. This staircase signal 4
1 is input to the negative input terminal of comparator OP402 and compared with the signal supplied from terminal 42 to the positive input terminal of comparator OP402. This signal is a constant voltage determined by voltage dividing resistors R401 and R402, and for example, as shown in FIG.
It is used for the reference signal indicated by the same symbol as 2. comparator
OP402 outputs a low-level signal from terminal 40 as shown with the same reference numeral as this terminal in FIG. 7 while signal 41 exceeds reference signal 42 (between instants T ₁ and T ₂ in FIG. 11). do.

Note that although the reference signal 42 is fixed in the above,
By making the resistor R401 or R402 variable according to the engine operating condition, the reference signal 42 can be changed to a value that matches the operating condition.

Thus, while the signal 40 is at a low level, the knocking detection device determines that the engine is knocking, and in making this determination, the knocking detection device uses the half-wave rectified signal 10 and the reference level 20 as described above. Pulse signal 3 obtained by comparing
0 is integrated for each ignition cycle, and knocking is detected when the value exceeds the reference level.
By simply comparing the half-wave rectified signal 10 and the reference level 20, the number and size of the portion of the half-wave rectified signal 10 that exceeds the reference level 20 can be measured at the same time, and although the configuration is simple, there is no malfunction due to noise. It is possible to perform a reliable knocking judgment.

Arithmetic unit 500 and frequency/voltage conversion unit 6 of the present invention
The ignition timing control device consisting of the ignition timing controller 700 and the equal advance angle controller 700 is operated by the knocking determination signal 40 obtained as described above, and the details thereof will be explained block by block in sequence below.

FIG. 8 shows an example of the configuration of the calculation unit 500, which includes an amplifier OP501, a capacitor C501,
Resistors R501 to R503 and diode D501
The front stage is equipped with a monostable multivibrator consisting of: This monostable multivibrator is triggered when the knocking determination signal 40 changes from a high level to a low level, and outputs a waveform shown in FIG. 12 with the same symbol from a terminal 52. At the next stage of the monostable multivibrator, an integrator consisting of amplifiers OP502, C502 and R504 to R507 is provided,
This is connected to diodes D502 and D with different polarities.
It is connected to the terminal 52 via 503. Thus, the integrator can set the time constants for both integration directions independently, and the time constant for the down direction is determined by resistor R504 and capacitor C5.
02, and the time constant in the rising direction is the resistance R50.
5 and capacitor C502, respectively.
Note that diodes D504, D505 and resistor R
508 to R511 constitute a control circuit that limits the operating range of the integrator between the power supply voltage +V and 0. Therefore, when the integrator receives the signal from the terminal 52, it slowly rises while the signal is at a low level, saturates at the upper limit determined by resistors R510 and R511, and remains at a high level. It is possible to output a signal to the terminal 51 that rapidly decreases during the interval. This signal is shown with the same reference numeral as the corresponding terminal 51 in FIG.
If a high level of 2 occurs frequently, the signal 51 will step down and saturate at the lower limit determined by resistors R508 and R509.

Note that the high level time of the signal 52 is a fixed time determined by the monostable multivibrator mentioned above, and the amount that the integrator integrates in the downward direction at one time with this high level signal is constant, and this can be expressed as, for example,
It is best to set it to the equivalent of 0.5 degree retard. At this time, the integrator output 51 corresponds to the number of high level occurrences of the signal 52, so it can be used as an ignition timing correction value.

A polarity inversion amplifier circuit consisting of resistors R512 to R519 and an operational amplifier OP503 is provided at the next stage of the integrator. In addition to converting the polarity, adjust the level,
The terminal 50 outputs a signal shown in FIG. 12 with the same reference numeral as this terminal.

FIG. 9 shows an example of the configuration of the frequency/voltage converter 600. This block is a circuit part that converts the engine rotational speed into voltage. For example, the ignition command signal 4 is converted into a constant width pulse by a monostable multivibrator composed of a capacitor C601, resistors R601 to R604, a diode D601, and an operational amplifier OP601. This pulse signal is converted into a signal and sent to the next stage of resistors R605 to R615 and capacitor C6.
02 and operational amplifiers OP602 and OP603, it is converted into an analog voltage and output from the terminal 60. Thus, this analog voltage has a value corresponding to the engine speed.

FIG. 10 shows a configuration example of the equal advance angle control section 700. This block consists of transistors T701-T7
03, resistors R701 to R704 and capacitor C
701, which differentiates the ignition command signal 4, turns on the transistor T703 every time the ignition command signal 4 rises, and short-circuits the capacitor C702 to reset it. Since the transistor T703 is made non-conductive immediately after this reset, the capacitor C702 is charged by the analog voltage (engine speed) from the terminal 60 via the voltage/current conversion circuit 78 with a current proportional to the engine speed. Ru. Therefore, a voltage appears at terminal 71, which is indicated by the same reference numeral as this terminal in FIG. However, as mentioned above, since the charging current of capacitor C702 is proportional to the engine speed, when the engine speed is 2400 rpm,
Figures 13a and 13 show the times of 1200rpm and 1200rpm, respectively.
As is clear from the comparison in FIG. b, the voltage waveform 71 in terms of crank angle is constant regardless of the engine speed, and is a constant advance integral waveform.

The voltage/current conversion circuit 73 has a configuration as shown in FIG. 11, and in this circuit, the voltage 60 proportional to the rotational speed is supplied to the positive input terminal of the differential amplifier OP750 via a resistor R752.
Now, for convenience of explanation, the value of voltage 60 is expressed as V ₆₀ ,
The output voltage of terminal 75 is V ₇₅ , and the differential amplifier OP750
Let the voltage at the positive input terminal be V ₊ , the voltage at the negative input terminal V _- , and the voltage at the output terminal V ₂ ,
Assuming that the resistance values of resistors R750 to R753 are the same, the voltage V ₊ is the difference between differential amplifier OP751 and resistor 7.
Since there is a feedback circuit including 53, V ₆₀ +V ₇₅ /2 and the voltage V _- becomes V ₂ /2. Also, the differential amplifier OP750 has an output V ₂ of V ₆₀ in the presence of the feedback circuit described above.
It operates so that +V ₇₅ . Therefore, resistor R75
The potential difference between both ends of the terminal 4 becomes V ₆₀ +V ₇₅ -V ₇₅ =V ₆₀ , and the current passing through this resistor, that is, the output current at the terminal 75 becomes V ₆₀ /R754, and the input voltage 6 is proportional to the vehicle speed.
Always proportional to 0. Therefore, the output current of the terminal 75 is controlled by the input voltage 60 and has a value that is always proportional to the vehicle speed, and the charging speed of the capacitor C702 charged with this current is determined by the vehicle speed, and the uniform advance angle integral waveform 71 is determined by the vehicle speed. can be obtained. The equiadvanced integral waveform from the terminal 71 is connected to the operational amplifier OP.
The signal 50 is input to the plus side input terminal of 701, and the signal 50 is input to the minus side input terminal thereof.
Operational amplifier OP701 receives both these signals 71, 50
As is clear from FIG. 12, a retard signal having a negative polarity pulse with a time width such that the signal 71 is lower than the level of the signal 50 is output from the terminal 72,
This retard signal is shown in FIG. 12 with the same reference numeral as the corresponding terminal 72. Note that if the equal advance angle integral waveform 71 is set to saturate at a crank angle of 30 degrees as shown in FIG. 13, the negative pulse width of the retard signal 72 will never exceed a crank angle of 30 degrees. This prevents the ignition timing from being retarded by more than 30 degrees even if there is a malfunction in the calculation, thereby preventing engine stalling.

Then, the retard signal 72 is input to the AND gate G701 together with the ignition command signal 4, and this AND gate is connected to the terminal 70 by the logical product of both input signals.
Therefore, a corrected ignition timing signal shown with the same reference numeral as this terminal in FIG. 12 is output. This corrected ignition timing signal drives the ignition coil 3 to the corrected ignition timing via the ignition coil drive unit 2 shown in FIG. 1, thereby suppressing the occurrence of knocking.

Thus, as described above, the ignition timing control device of the present invention calculates (integrates) so as to retard the engine by a predetermined amount equivalent to the crank angle each time the knocking determination signal 52 is input, and the ignition timing control device performs the calculation (integration) so that the ignition timing retards by an amount equivalent to a predetermined crank angle every time the knocking determination signal 52 is input. Calculation (integration) is performed so that the angle constantly returns to the advance direction at a slower rate of time than the calculation in the angle direction (see 50 in Figure 12).
The arithmetic unit 500 compares the uniform advance angle integral waveform 71 that is reset each time the ignition command signal 4 is input and rises to a predetermined level at a speed corresponding to the engine speed, and the arithmetic unit output 50 to calculate the output 50. Since the configuration includes a constant advance control section 700 that obtains a retard signal 72 with a pulse width corresponding to the level and delays the ignition timing by the pulse width, the retard signal 72 is immediately retarded when the knocking determination signal 52 is output. Furthermore, after this retard angle control, when the next knocking judgment signal is not output, the calculation in the advance direction is performed more slowly than the calculation in the retard direction as described above, so that the next knocking judgment Even if no signal is input, the ignition timing will not immediately return to its original state. Therefore, if knocking no longer occurs due to the above retard control, it will immediately return to the original ignition timing and knocking will occur again. It is possible to prevent so-called control hunting, in which the retard control is performed again in order to prevent this. Therefore, the device of the present invention not only can quickly and reliably suppress the occurrence of knocking by performing ignition timing control for preventing knocking in a responsive manner, but also can suppress the occurrence of knocking even when the knocking determination signal 52 is output at a low frequency, even in the case of mild knocking. Timing control can be performed stably without occurrence of hunting, and even the slight knocking can be reliably prevented.
In addition, since the amount of retardation for preventing knocking (pulse width of the signal 72) increases as the output frequency of the knocking judgment signal 52 (strength of knocking) increases, the amount of retardation that eliminates knocking can be reliably obtained without delay. This makes it possible to quickly and reliably prevent knocking.

Furthermore, while the knocking judgment signal 52 is not input, the calculated value 50 is continuously returned to the retard direction without waiting for the ignition signal, so even at low engine speeds where the ignition gap becomes long, the knocking judgment signal 52 is not input. When the ignition timing is not input, the calculated value 50 can be quickly returned to the advance direction, and knocking is unlikely to occur in this low engine speed range. This eliminates the problem of poor engine fuel efficiency. In addition, since the calculated value 50 is returned to the advance direction while the knocking judgment signal 52 is not inputted, the ignition interval is continuously changed at a slower time rate than the change in the retard direction, regardless of the ignition signal. Even under a high engine rotational speed that decreases, when the knocking judgment signal 52 is not input, the calculated value 50 can be returned to the advance direction at the above-mentioned time rate, and the return of the calculated value can be made by adjusting the engine rotational speed. Comparisons can be made relatively slowly. Therefore, it is possible to eliminate the problem that knocking is likely to occur in the high engine speed range, and that even though it is desired to slowly return the ignition timing in the forward direction, the ignition timing is returned too quickly and the above-mentioned hunting occurs.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the ignition timing control device of the present invention together with a knocking detection device, Fig. 2 is a circuit diagram of the sensor processing section thereof, Fig. 3 is a circuit diagram of the smoothing section, and Fig. 4 is a circuit diagram of the comparison section. Circuit diagram, Fig. 5 is a circuit diagram of the knocking intensity detection section, Fig. 6 is an explanation diagram of operating waveforms of the smoothing section and comparison section, Fig. 7 is an explanation diagram of operating waveforms of the knocking intensity detection section, and Fig. 8 is an illustration of the operation section. 9 is a circuit diagram of the frequency/voltage conversion section, FIG. 10 is a circuit diagram of the constant advance angle control section, and FIG. 11 is a circuit diagram of the voltage/current conversion circuit used in the constant advance angle control section.
FIG. 12 is an explanatory diagram of the operation waveforms of the equal advance angle control section,
FIG. 3 is an explanatory diagram of a constant advance angle integral waveform. 1... Vibration sensor, 2... Ignition coil drive unit,
3...Ignition coil, 4...Ignition command signal input terminal, 10...Half wave rectification signal output terminal, 20...Smoothing level output terminal, 30...Comparison pulse signal output terminal, 40...Knocking judgment signal output terminal , 4
1... Integral waveform output terminal, 42... Comparison level output terminal, 43... Differential pulse signal output terminal, 50
...Polarity inversion amplified signal output terminal, 51...Integrator output terminal, 52...Monostable multivibrator output terminal, 60...Analog voltage output terminal, 70
... Corrected ignition timing signal output terminal, 71 ... Equal advance angle integral waveform output terminal, 72 ... Retard angle signal output terminal,
73...Voltage/current conversion circuit, 75...Current output terminal, 100...Sensor processing section, 200...Smoothing section, 300...Comparison section, 400...Knocking intensity detection section, 500...Calculation section, 600 . . . Frequency/voltage conversion section, 700 . . . Equal advance angle control section.

Claims (1)

[Claims] 1. In an internal combustion engine in which the ignition timing is retarded by a calculated value that is changed by a signal for determining knocking, the calculated value is immediately changed by an amount equivalent to a predetermined crank angle each time the knocking determination signal is input. The calculated value changes in the retard direction, and while the knocking judgment signal is not input, the calculated value moves in the advance direction at a slower rate than the change in the retard direction of the calculated value with respect to time. The calculated value is compared with a calculation unit that calculates the values to be returned continuously and a constant advance integral waveform that is reset each time an ignition command signal is input and then reaches a predetermined level at a speed corresponding to the engine speed. ignition of an internal combustion engine, characterized in that it is equipped with a constant advance angle control section that obtains a retard signal with a pulse width corresponding to the magnitude of the calculated value, and retards the ignition timing by the pulse width. Timing control device.