JPS632029B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for suppressing knocking in an internal combustion engine.

It is desirable to set the ignition timing of an internal combustion engine in such a way as to maximize the efficiency for the engine's operating conditions.
It is desirable to set the ignition timing so that it approaches the best torque. However, most conventional ignition timing control devices are mechanical, and the ignition advance characteristics are not stable due to product variations or changes over time. It is set far behind the angular characteristics, and the actual efficiency of the engine is deteriorating.

On the other hand, in the case of an ignition timing control device that sets the standard ignition advance characteristic in advance to the advance side in order to approach the above-mentioned MBT and performs timely retard control in response to occurrence of knocking, the ignition timing may be controlled to the optimum ignition timing. Can be done.

However, even in this type of conventional device,
When the load characteristics are set to emphasize the power performance of the engine, or when the load on the engine increases rapidly, the amount of control for knocking during transient times that occurs may be insufficient, and the knocking noise may become louder. This causes a decrease in feeling and greatly affects its marketability.

This invention has been made by focusing on the above points, and is an ignition timing control device for suppressing knocking in an internal combustion engine, which improves controllability against transient knocking and improves feeling compared to conventional devices. The purpose is to provide the following.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows one embodiment of this invention.
2 is an acceleration sensor that is attached to the internal combustion engine and detects the vibration acceleration of the engine; 2 is a frequency filter that passes a signal component of a frequency that is sensitive to knocking among the output signals of the acceleration sensor 1;
Reference numeral 3 denotes an analog gate that suppresses noise that becomes an interference wave when detecting a knock in the output signal of the frequency filter 2, and 4 a gate timing that instructs the analog gate 3 to open or close in response to the generation time of the interference noise. a controller; 5 a noise level detector for detecting the level of mechanical noise of the internal combustion engine other than knocking; 6 comparing the output voltage of the analog gate 3 with the output voltage of the delay circuit 13 to generate a knock detection pulse; A comparator 7 integrates the output pulse of the comparator 6 and generates an integrated voltage according to the knocking intensity. A shifter 8 changes the phase of the reference ignition signal according to the output voltage of the integrator 7. A phaser, 9, a rotation signal generator, 10, which generates an ignition signal according to a preset ignition advance characteristic.
11 is a waveform shaping circuit that shapes the output of the rotational signal generator and at the same time controls the closing angle of energization of the ignition coil 12; 11 is a switching circuit that turns on and off the energization of the ignition coil 12 according to the output signal of the phase shifter 8; It is. Note that the delay circuit 13 provides a delay characteristic to the output of the noise level detector 5, and its response speed is set to be slow only when the output level becomes large.

FIG. 2 shows the frequency characteristics of the output signal of the acceleration sensor 1, where A shows the case where knocking does not occur and B shows the case where knocking occurs.

The output signal of the acceleration sensor 1 includes mechanical noise of the internal combustion engine other than the knock signal and various noise components on the signal transmission path, such as ignition noise. Comparing A and B in FIG. 2, it can be seen that the knock signal has unique frequency characteristics. Although this distribution differs depending on the engine or the mounting position of the acceleration sensor 1, there is a clear difference in the distribution depending on the presence or absence of knocking in each case. Therefore, by passing the frequency component of this knock signal, the noise of other frequency components can be suppressed, and the knock signal can be detected efficiently.

Figures 3 and 4 show the operating waveforms of each part in Figure 1, and the same symbols indicate the waveforms of the same parts.
The figure shows a mode in which knocking of the internal combustion engine does not occur, and FIG. 4 shows a mode in which knocking occurs in the engine.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

The rotation signal generated by the rotation signal generator 9 in accordance with the ignition timing characteristics set in advance by the rotation of the internal combustion engine is waveform-shaped by the waveform shaping circuit 10 into opening/closing pulses having a desired closing angle, and then phase-shifted. The switching circuit 11 is driven through the switch 8 to turn on and off the energization of the ignition coil 12, and the engine is ignited and operated by the ignition voltage of the ignition coil 12 generated when the energization current is cut off. Engine vibrations occurring during operation of the internal combustion engine are detected by the acceleration sensor 1.

If knocking is not occurring in the internal combustion engine, engine vibration due to knocking will not occur, but due to other mechanical vibrations, the output signal of the acceleration sensor 1 may include mechanical noise and noise as shown in Figure 3a. Ignition noise occurs on the signal transmission path at ignition timing F. When this signal passes through the frequency filter 2, the mechanical noise component is considerably suppressed as shown in Figure 3b, but the ignition noise component is strong and is output at a high level even after passing through the frequency filter 2. Sometimes. If this continues, the ignition noise will be mistakenly recognized as a knock signal, so the analog gate 3 will shift the ignition timing from the ignition timing by the output of the gate timing controller 4 (FIG. 3c), which is triggered by the output of the phase shifter 8. Close that gate for a period of time to eliminate ignition noise. Therefore, only low-level mechanical noise remains in the output of the analog gate 3, as shown in FIG. 3(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. That is, this is because it has the characteristic of being able to respond to relatively gentle changes due to the peak value of normal mechanical noise. In this case, the noise level detector 5 generates a DC current as shown in FIG. 3(d), which is slightly higher than the peak value of the mechanical noise. This DC current is input to the comparator 6 via the delay circuit 13. Therefore, as shown in FIG. 3a, the output of the noise level detector 5 is larger than the average peak value of the output signal of the analog gate 3, so the output of the comparator 6 for comparing these is as shown in FIG. 3e. As in, nothing is output, and all noise signals are eventually removed. Therefore, the output voltage of the integrator 7 remains zero as shown in FIG. 3f, and the phase shift angle by the phase shifter 8 (the phase difference between the input and output g and h in FIG. 3) 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 the same phase as the reference ignition signal output from the waveform shaping circuit 10, and the ignition timing becomes the reference ignition timing F. .

Next, 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 Figure 4a, and the signal after passing through the frequency filter 2 and analog gate 3. In this case, the knock signal is largely superimposed on the mechanical noise, as shown in Fig. 4(d). Among the signals that have passed through the analog gate 3, the rise of the knock signal is steep, so the level of the output voltage of the noise level detector 5 is delayed in response to the knock signal, and the level of the output of the delay circuit 13 does not fluctuate much. . As a result, the inputs of the comparator 6 are A and B in FIG. 4d, respectively, so the output of the comparator 6 is
A pulse is generated as shown in Figure e. The integrator 7 integrates this pulse and generates an integrated voltage as shown in FIG. 4f. In accordance with this integrated voltage, the phase shifter 8 shifts the output signal of the waveform shaping circuit 10, that is, the reference ignition signal shown in FIG. It lags behind the phase of the reference ignition signal, and eventually drives the switching circuit 11 with the phase shown in FIG. 4h. As a result, the ignition timing is delayed and knocking can be suppressed.

The conditions shown in FIGS. 3 and 4 are repeated to finally obtain optimal ignition timing control.

By the way, if controllability during steady state is set to a control characteristic that emphasizes the power characteristics of the internal combustion engine, the amount of control will be insufficient for transient knocking when the load on the engine increases rapidly, and as a result, a large knocking noise will occur. The feeling may deteriorate. As is clear from the above explanation, this is due to the comparison standard of the comparator 6 detecting knocking, that is, the fourth
As the output of the noise level detector 5 rises quickly as shown in Fig. d (b), the knocking detection amount is insufficient.
This is because as a result, control becomes insufficient.

In order to avoid such a lack of knocking detection amount, in the embodiment of the present invention, the delay circuit 1
3, the output response of the noise level detector 5 is delayed and then inputted to the comparator 6, so that the comparison standard of the comparator 6 when the load on the internal combustion engine suddenly increases, i.e. Fourth
In Figure d, B gradually increases with a delay, and the detected amount of knocking increases accordingly. Further, the output of the delay circuit 13 becomes the same level as the output of the noise level detector 5, and continues to operate at a steady level, and the comparison reference of the input of the comparator 6 becomes the steady state value, and a predetermined controllability is achieved. return.

In addition, when the output of the noise level detector 5 decreases, the delay circuit 13 shortens the delay time by increasing the responsiveness to the decrease, thereby reducing the delay time when the load on the internal combustion engine increases rapidly. The response to a rise in the output of the noise level detector 5 is delayed.

FIG. 5 is a circuit diagram showing an example of the delay circuit 13,
20 and 21 are resistors, 22 is a diode, and 23 is a capacitor. Therefore, when the input level of the delay circuit 13 increases, the capacitor 23 is charged via the resistors 20 and 21 in FIG. 5, whereas when the input level decreases, the charge on the capacitor 23 is The diode 22 bypasses the resistor 21 and discharges only through the resistor 20. That is, in the delay circuit 13, when the input level increases, the resistors 20 and 21 and the capacitor 23
When the input level drops, the resistance due to the resistor 20 and the capacitor 23 becomes a problem. Therefore, when the engine load suddenly decelerates as mentioned above, it responds quickly to the output of the noise level detector 5, so even if sudden acceleration is performed immediately after, the comparison standard is the same level as when sudden acceleration from a steady state occurs. , so transient knocking can be detected accurately.

Also, by changing the responsiveness in this way,
The output of the delay circuit 13 will decrease for the same output of the noise level detector 5, but this can be corrected by increasing the gain of the noise level detector 5. Since the output of the circuit 13 can be kept unchanged, the knocking detection level remains unchanged.

As explained above, the present invention detects the vibration of an internal combustion engine using an acceleration sensor, and compares the level of the detected output with a comparison reference voltage set from the mechanical noise of the detected output to detect knocking, and detect the knocking intensity. In an ignition timing control device for an internal combustion engine that controls ignition timing in accordance with the engine, the engine It is possible to accurately and efficiently detect transient knocking not only when the load suddenly increases from a steady state, but also when the load suddenly increases immediately after sudden deceleration, and has the effect of preventing a decrease in feeling due to transient knocking noise. be. Furthermore, since this invention has a new technical configuration that allows the delay characteristic to be set without affecting controllability in steady state, the above-mentioned problem that is likely to occur especially when setting control characteristics with emphasis on power performance can be solved. It has a remarkable effect on suppressing transient knocking.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram showing an embodiment of the present invention, Fig. 2 is an output characteristic diagram of the acceleration sensor shown in Fig. 1, Figs. 3 and 4 are operation waveform diagrams of various parts in Fig. 1,
FIG. 5 is a circuit diagram showing an example of a delay circuit. 1... Acceleration sensor, 2... Frequency filter, 3...
Analog gate, 4...gate timing controller,
5... Noise detector, 6... Comparator, 7... Integrator, 8
... Phase shifter, 9... Rotation signal generation circuit, 10... Waveform shaping circuit, 11... Switching circuit, 12... Ignition coil, 13... Delay circuit, 20, 21... Resistor, 22
...Diode, 23...Capacitor.

Claims (1)

[Claims] 1 The output of the acceleration sensor that detects the vibration acceleration of the internal combustion engine, the noise level detection circuit that detects the mechanical noise level from the output of the acceleration sensor, and the noise level detection circuit is delayed, and the output of the noise level detection circuit is decreased. a delay circuit that reduces the delay time when the output of the noise level detection circuit increases and increases the delay time when the output of the noise level detection circuit increases;
a comparator that compares the output of the acceleration sensor and the output of the delay circuit and generates a knock detection signal when the output of the acceleration sensor is larger; a reference ignition timing signal generator that generates a reference ignition timing signal; and the comparator. Ignition timing control for an internal combustion engine, characterized by comprising a phase shifter that changes a reference ignition timing signal according to the output of the phase shifter, and a switching circuit that turns on and off energization of an ignition coil in synchronization with the output of the phase shifter. Device.