JPS61234274A - Ignition timing control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To reliably detect a fail state, by providing a means which actuates fail function when the period of a knocking signal component, selected by a discriminating means, differs from a given value. CONSTITUTION:An analogue gate 3 shuts off the noise, forming an impedance wave to detection of knock, of an output signal from a frequency filter 2. A comparator 6 generates a knock detecting pulse. A phase shifter 8 displaces the position of a reference ignition signal according to the output voltage of an integrator 7. A switching circuit 11 controls the feed to an ignition coil 12. A pulse width deciding device 32 decides from the measurement output of a pulse width counter 31 whether an output pulse from the comparator 6 has a given pulse width, and an output therefrom is inputted as a fail signal to the integrator 7. This enables reliable detection of a fail state in relation to the whole of a knock detecting part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for an internal combustion engine that controls knocking in the internal combustion engine.

It is desirable to set the ignition timing of an internal combustion engine to be the most efficient for the engine's operating conditions, and generally, the ignition timing should be set as much as possible without causing the engine to knock.1) M B T
(Minium advance for Be5t
It is desirable to set the ignition timing to be advanced so that it approaches the torque.

However, if the ignition timing is advanced too much, knocking will occur excessively, which is a problem that not only reduces operating efficiency but also leads to engine damage.

For this reason, an ignition timing control device that controls the ignition timing to the optimum ignition timing by setting the ignition advance characteristic in advance to the advance side in order to approach the reference ignition advance characteristic t-MBT, and performing timely retard control in response to the occurrence of knocking. Is required.

[Conventional technology]

The conventional ignition timing control device for an internal combustion engine shown in FIG. 3 will be described below.

In FIG. 3, 1 is an acceleration sensor that is attached to the engine and detects the vibration acceleration of the engine, 2 is a frequency filter that passes signal components of frequencies that are sensitive to knocking among the output signals of the acceleration sensor 1, and 3 is an analog gate that blocks noise that becomes an interference wave for knock detection in the output signal of the frequency filter 2.

The opening and closing of this analog gate 3 is controlled by a dirt timing controller 4 in accordance with the timing of generation of disturbance noise.

The output of the analog dirt 3 is introduced into a comparator 6 and a noise level detector 5, and the noise level detector 5 detects the level of mechanical vibration noise of the engine other than knocking and outputs it to the comparator 6. 0 The comparator 6 compares the output voltage of the analog dart 3 and the output voltage of the noise level detector 5, generates a knock detection pulse I4, and sends this knock detection pulse to the integrator 7.

An integrator 7 integrates the output power of the comparator 6 and generates an integrated voltage corresponding to the knocking intensity. The phase shifter 8 shifts the position of the reference ignition signal in accordance with the output voltage of the integrator 7.

On the other hand, the rotation signal generator 9 is designed to generate an ignition signal according to a preset ignition advance characteristic. The output of this rotational signal generator 9 is waveform-shaped by a waveform shaping circuit 10, and at the same time, the ignition coil 12 is shaped by this waveform shaping circuit 10.
The closing angle of energization is controlled.

Further, the switching circuit 11 is configured to intermittent power supply to the ignition coil 12 based on the output signal of the phase shifter 8.

FIG. 4 shows the frequency characteristics of the output signal of the acceleration sensor 1. In this Fig. 4, A is when there is no knocking, B is
is the case where knocking occurs.

The output signal of the acceleration sensor 1 includes a knock signal (a signal generated due to knocking), mechanical noise from other engines, and various noise components on the signal transmission path, such as ignition noise. Comparing Figure 4 OA and B, it can be seen that the knock signal has a unique frequency characteristic. Although this distribution varies depending on the engine or the mounting position of the acceleration sensor 1, In this case, there is a definite difference in the BA distribution depending on the presence or absence of knocking. Therefore, by passing the frequency component of this knock signal, noise of other frequency components can be suppressed, and the knock signal can be detected efficiently.

5 and 6 show the operating waveforms of each part in FIG. 3, and the same reference numerals indicate the waveforms of the same parts. FIG. 5 shows a mode in which engine knocking does not occur.

Figure 6 shows a situation where engine knocking occurs.

Next, the operation of the ignition timing control device for an internal combustion engine shown in FIG. 3 will be explained. The ignition signal generated by the rotation signal generator 9 in accordance with the ignition timing characteristics set in advance by the rotation of the engine is waveform-shaped by the waveform shaping circuit 10 into opening/closing pulses having a desired closing angle. Switching circuit 1 through 8
1, the power supply to the ignition coil 12 is intermittent, and the engine is ignited and operated by the ignition voltage of the ignition coil 12 generated when the energizing current is cut off. Engine vibrations occurring during operation of the engine are detected by an acceleration sensor 1.

If knocking is not occurring in the engine, engine vibration due to knocking will not occur, but due to other mechanical vibrations, the output signal of the acceleration sensor 1 will be affected by the output signal shown in Figure 5.
As shown in a), mechanical noise and ignition noise on the signal transmission path occur at the ignition timing F.

By passing this signal through the frequency filter 2, the mechanical noise component is considerably suppressed as shown in Fig. 5(b), but the ignition noise component is strong and remains at a large level even after passing through the frequency filter 2. may be output.

If this continues, the ignition noise will be mistaken for a knock signal, so the analog dart 3 will be triggered by the output of the phase shifter 8. Close that dart for a period of time and block out the ignition noise. Therefore, only low-level mechanical noise remains in the output of the analog gate 3, as shown in FIG. 5(d).

On the other hand, the noise level detector 5 responds to changes in the peak value of the output signal of the analog gate 3, and in this case, has the characteristic of being able to respond to relatively gentle changes due to the peak value of normal mechanical noise. A DC voltage slightly higher than the peak value of the noise is generated (the opening in FIG. 5(d)).

Therefore, as shown in FIG. 5(A), since the output of the noise level detector 5 is larger than the average peak value of the output signal of the analog gate 3, a comparator 6 is used to compare them.
Nothing is output as shown in FIG. 5(e), and all noise signals are eventually removed.

Therefore, the output voltage of the integrator 7 remains zero as shown in Fig. 5(f), and the phase shift angle by the phase shifter 8 (input/output Fig. 5)
The phase difference (as shown in Figure 5) also becomes zero.

Therefore, the opening/closing phase of the switching circuit 11 driven by this output, that is, the intermittent phase of energization of the ignition coil 12, is in phase with the reference ignition signal output from the waveform shaping circuit 101Z), and the ignition timing is the same as the reference ignition timing. Become.

In addition, when knocking occurs, the output of the acceleration sensor 1 includes a knocking signal around a certain time delay from the ignition timing, as shown in FIG. 6(a), and passes through the frequency filter 2 and analog dart 3. As shown in Fig. 6(d), the knock signal is largely superimposed on the mechanical noise.

Since the rise of the knock signal among the signals passing through the analog gate 3 is steep, the response of the output voltage level of the noise level detector 5 to the knock signal is delayed. As a result, the inputs of the comparator 60 become A and A of FIG. 6(d), respectively, and a pulse is generated at the output of the comparator 6 as shown in FIG. 6(e).

An integrator 7 integrates the pulse and generates an integrated voltage as shown in FIG. 6(f). Then, the phase shifter 8 shifts the phase of the output signal of the waveform shaping circuit 10 (Fig. 6) (reference ignition signal) to the delayed side in accordance with the output voltage of the integrator 7. The phase of the output of the device 8 lags behind the phase of the reference ignition signal of the waveform shaping circuit 10, and drives the switching circuit 11 with the phase shown in FIG.

As a result, the ignition timing is delayed and knocking is suppressed. Eventually, the conditions shown in FIGS. 5 and 6 are repeated to achieve optimal ignition timing control.

By the way, in the conventional example shown in FIG. 3 above, the acceleration sensor 1 or the acceleration sensor 1 and the frequency filter 2
If an abnormality occurs in the signal line installed between the There is a risk of introducing damage.

For this reason, a failsafe circuit 13 is provided.

This fail-safe circuit 13 will be explained using FIG. 7.

In FIG. 7, the acceleration sensor 1 is composed of a piezoelectric element 21 and a resistor 22.
They are connected in parallel, with one end connected to ground and the other end connected to the output terminal 23 of the acceleration sensor 1.

The output terminal 23 of the acceleration sensor 1 is connected to the knock detection circuit 101
0 input terminal 24 (which is also the input of frequency filter 2). The resistor 25 is connected between the power supply 26 and the input terminal 24, and the non-inverting input terminal of the voltage comparator 27 is connected to the input terminal 24, and the inverting input terminal is connected to the reference voltage Vr28. The output of voltage comparator 27 is the output of fail-safe circuit 13.

A voltage is applied to the acceleration sensor 1 from a power source 26 via a resistor 25 . If the acceleration sensor 1 has a built-in resistor 22 and the resistors 22 and 25 each have the same resistance value R, the voltage ■+ at the input terminal 24 is 0.5 V during normal operation.
(V is the voltage of the power supply 26). For example, if the signal line connecting the output terminal 23 of the acceleration sensor 1 and the input terminal 24 of the knock detection circuit is disconnected, the voltage V+ of the input terminal 24 becomes V. Become.

The voltage comparator 27 compares the voltage V0 of the input terminal 24 (non-inverting input voltage) with the reference voltage Vr28 (inverting input voltage), so that the reference voltage Vr is set to 0.5 V<
If Vr < V, under normal conditions V+ = 0-5V <
V-=Vr! voltage comparator 2701fi power is low,
When the above signal line is disconnected, V+ = V > V - = V
r, the output of the stain pressure comparator 27 becomes high. That is,
When the signal line is abnormal, the exposure output of the voltage comparator 27 becomes high.

As shown above, the output of the fail-safe circuit 13 (output of the voltage comparator 27) is input to the integrator 7, and when the output of the 7-Ruse 7 circuit 3 becomes high, the integrator 7 is forced to The output is set to a predetermined value, and the ignition timing is set to a safe angular position where no knocking occurs in one engine or only slight knocking that does not damage the engine occurs by performing retard control at a constant angle.

[Problem that the invention seeks to solve]

In the conventional device shown in FIG. 3, in order to detect a failure state of the acceleration sensor or the wiring between the acceleration sensor and the frequency filter 2, as shown in FIG. Added resistor 25 to 101.

Of these, it is usually relatively easy to incorporate the resistor 25 into the knock detection circuit 101, but incorporating the resistor 22i into the acceleration sensor 1 not only takes up internal space, but may also affect its detection characteristics. Therefore, it is not necessarily an easy task.

On the other hand, the drive system of recent automobiles is FF, and electronic control is progressing, so the engine characteristics are narrow and the number of various sensors and actuators installed on the engine is extremely large, increasing acceleration. It is now more important than ever that the sensor 1 is small.

Furthermore, the conventional device has a problem in that an abnormality in the knock detection circuit consisting of the frequency filter 2 to the comparator 6 cannot be detected.

The frequency filter 2 shown in the conventional device of FIG.
.

(hereinafter referred to as BPF). The detection output of the acceleration sensor 1 is a signal having a broadband frequency component, but the above-mentioned BP
The signal is limited to a specific band component and outputted at F2, and subsequent circuits perform calculations based on this band-limited signal.

The present invention was made to solve these problems, and allows the use of an acceleration sensor that is easy to manufacture, and also reliably detects the failure state of the entire knock detection section from the acceleration sensor to the comparator. The object of the present invention is to obtain an ignition timing control device for an internal combustion engine that is capable of controlling the ignition timing of an internal combustion engine.

[Means for solving problems]

The ignition timing control device for an internal combustion engine according to the present invention extracts the knocking signal component from the output of the acceleration sensor by limiting the frequency band using a frequency filter, and if the period of the extracted signal differs from a predetermined value, the knocking signal component is extracted from the output of the acceleration sensor. means for activating the function.

[For production]

In this invention, the noise signal component is removed from the output of the acceleration sensor, the knocking signal component is extracted by limiting the frequency band, and when the pulse width of the extracted knocking signal component is different from a predetermined period, Activate the tool function.

〔Example〕

Embodiments of the ignition timing control device for an internal combustion engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment.

In FIG. 1, parts that are the same as those in FIG. 3 are given the same reference numerals, and their explanation will be omitted, and the explanation will mainly focus on the parts that are different from FIG. 3.

As is clear from comparing Figure 1 with Figure 3,
In the figure, parts 1 to 12 shown in FIG.
A loop width setting device 32 is provided.

That is, the pulse width kakunta 31Fi measures the time width of the output pulse of the comparator 6, and the pulse width determiner 32 calculates the output a4 of the comparator 6 from the measured output of the pulse width counter 31. It is determined whether the pulse has a predetermined pulse width or not, and its output is input to an integrator 7 as a fail signal.

Next, the operation of this invention will be explained. First, the time width of the output pulse of the comparator 6 will be explained.

As mentioned above, the frequency components of the output of the acceleration sensor 1 are band-limited by the BPF 2. Therefore, one input of the comparator 6 (A in FIG. 5(d) and A in FIG. 6(d)) is a band component centered on the center frequency f0 of the BPF 2.

Comparator 6 connects the output of BPF2 and noise level detector 5.
Compare the output of Fig. 6 (a)) and the output of BPF2 (
When a) in FIG. 6(d) becomes larger than the output of the noise level detector 5 (portion in FIG. 6(d)), a knock signal is output.

Therefore, the pulse width Pw of the knock signal output from the comparator 6 (FIG. 2(b)) is approximately Pw = 'A·fo.

This is shown in FIG. 2(a) shows the input to the comparator 60, the curve a in FIG. 2(&) is the output of the BPF 2, and the broken line is the output of the noise level detector 5. These a,
b is compared by a comparator 6, and a knock signal is output.

As mentioned above, curve a is a signal with the center frequency f0 of BPF2 as the main component of gold, and comparing this with the level of the dashed line A,
Since a knock signal (pulse width Pw) appears at the output of the comparator 6 corresponding to the period a)b, the pulse width Pw of the knock signal is at most 0.fo.

The pulse width counter 31 measures the pulse width of the knock signal output from the comparator 6. The pulse width determiner 32 determines from the measurement data of the pulse width counter 31 whether the pulse width of the knock signal output from the comparator 6 is in a normal state of less than a predetermined value or in an abnormal state of more than a predetermined value.

In other words, if Pw≦de・fo, it is normal, and Pw >'A・
If it is fo, it is determined to be abnormal. When an abnormal condition is detected, a 7-hour signal is output to the integrator 7, and the ignition timing is set to a predetermined angular position at 7 hours.

In the above example, the p4 pulse width of the output of the comparator 6 is measured, but it is also possible to measure the period of the output of the BPF 2 or the output of the analog gate 3. It is possible to make the entire system more appropriate by measuring the pulse width (operation of the pulse width counter 31) or determining the pulse width (operation of the pulse width determiner 32) in accordance with a specific operating region. This is not intended to limit the invention.

〔Effect of the invention〕

As described above, the present invention is an ignition system that detects a knock signal generated in an engine, retards the ignition timing according to the detected amount, and performs knock suppression. This limited signal is processed to detect a knock signal, and when the period of the frequency component differs from the predetermined period, the 7-step function is activated. This has the excellent effect of being able to reliably detect the fail state of the entire knock detection section of the comparator 1 from the acceleration sensor, which can be easily constructed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the ignition timing control device for an internal combustion engine according to the present invention, FIG. 2 is a waveform diagram for explaining the operation of the ignition timing control device for the internal combustion engine, and FIG.
The figure is a block diagram of a conventional ignition timing control device for an internal combustion engine.
FIG. 4 is an output characteristic diagram of an acceleration sensor in a conventional ignition control device for an internal combustion engine, and FIGS. 5 and 6 are waveform diagrams of various parts for explaining the operation of the conventional ignition timing control device for an internal combustion engine, respectively. FIG. 7 is a circuit diagram showing a detailed configuration of a fail-safe circuit in a conventional ignition timing control device for an internal combustion engine. 1... Acceleration sensor, 2... Frequency filter, 3...
... Analog gate, 4... Gate timing controller, 5... Noise level detector, 6... Comparator, 7.
... Integrator, 8... Phase shifter, 9... Rotation signal generator, 10... Waveform shaping circuit, 11... Switching circuit, 12... Ignition coil, 13... Fail safe Circuit, 31.../pulse width counter, 32... pulse width judger. In addition, the same symbols in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] an acceleration sensor that detects vibration acceleration of an internal combustion engine; a discrimination means that removes noise signal components from the output of the acceleration sensor and limits the frequency band of knocking signal components corresponding to knocking occurring in the engine using a frequency filter; A reference ignition timing signal generating means for generating a reference ignition timing signal, a phase shifting means for changing the phase of the reference ignition timing signal in accordance with the output of the discriminating means, and a power supply to the ignition coil in response to the output of the phase shifting means. Ignition timing control for an internal combustion engine, characterized in that it comprises an intermittent switch means, a means for determining the cycle of the knocking signal component selected by the discrimination means and operating a fail function when the cycle differs from a predetermined value. Device.