JPS60175770A - Knocking controller - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a misjudgment for knocking in time of low engine speed in particular, by setting a proper difference to a bias level of an output signal of a sensor to detect vibrations in an engine and a reference signal obtainable of amplifying and equalizing this sensor signal. CONSTITUTION:Output of a sensor 1 detecting pressure inside a cylinder of an engine or vibrations, namely, a sensor is inputted into a comparator 5 on one side via an amplifier 2 and the other side into an equalizing circuit 4 via further an amplifier 3. And, the signal rectified and equalized at the equalizing circuit 4 is compared with the sensor signal at the comparator 5 as a reference signal judging a state of knocking. An output pulse of this comparator 5 is counted at a knock judging part 6, and when it exceeds the specified speed, it is judged as knocking whereby an ignition timing control part 7 is controlled. And, at this time, each of bias levels Va and Vb to be impressed on these amplifiers 2, 3 and the equalizing circuit 4 is controlled so as to be adjusted to Va<Vb by a bias circuit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a knocking control device that detects knocking occurring in an internal combustion engine and controls ignition timing.

Structure of conventional example and its problems FIG. 1 shows a conventional knocking control device. The configuration of this conventional example will be explained below with reference to FIG. 1.

In FIG. 1, reference numeral 1 denotes a sensor (pressure sensor) that converts the engine non-king phenomenon (pressure in the cylinder, engine vibration, etc.) into an electrical signal.

vibration sensor, etc.), 2.3 is an amplifier, 4 is an averaging circuit that rectifies and integrates the output signal of amplifier 3, 5 is a comparator, and 6 is a knock that determines the presence or absence and degree of knocking based on the output of comparator 5. The determining section 7 is an ignition timing control section, and 8 is a pickup coil provided in the distributor. The pickup coil 8 outputs a signal corresponding to a specific crank angle of each cylinder of the engine. 9 is a waveform shaping circuit, 10 is an amplifier, and 11 is an ignition coil.

Next, the operation of the above conventional example will be explained. In FIG. 1, an amplifier 2 amplifies the signal of the sensor 1,
A selective amplifier may be used for noise removal. Also,
The comparator 5 compares the output signal of the sensor 1 with the reference signal of the averaging circuit 40 which amplifies and averages the signal of the sensor 1, and outputs a pulse signal if the sensor signal is larger than the averaged output (reference signal). Output. Figure 2 shows this state, where A1 in Figure 2(a) is the sensor signal and A2
is the averaged signal, and FIG. 2(b) is the output of the comparator 5.

The knock determination section 6 determines whether knocking has occurred based on the output of the comparator 5, and for example, if the number of pulses output from the comparator 5 is equal to or greater than a predetermined number, it is determined that knocking has occurred. The ignition timing control section 7 calculates the ignition timing output from the non-king determination output based on the signal of the pickup coil 8 that generates the ignition timing of the engine, and outputs a retard control signal.

The amplifier 10 amplifies the output of the ignition timing control section 7 and drives the ignition coil 11 to ignite the spark plug.

However, in the above conventional example, since the average output is low in the low rotation range where the sensor signal level is small, the noise level such as engine cam rattling noise may exceed the average output even if non-king has not occurred, resulting in an erroneous determination. . Third
The figure shows a waveform when the output signal of sensor 1 is small. In FIG. 3(a), A1 indicates the sensor output, and A2 indicates the reference signal output from the averaging circuit 4. In FIG. Figure 3 (a
) in section N of the sensor output (A1) has a large amplitude due to noise superimposed on the sensor output. If the sensor output is at a low level, the reference signal level will also drop.
When a slightly large noise is superimposed on the sensor output, as shown in FIG. 3(b), a pulse may be output from the comparator 5 even though no knocking has occurred, resulting in an erroneous determination. On the other hand, if the amplification degree of the amplifier 3 is increased in order to eliminate such erroneous determinations, the sensor output increases in the high rotation range, which has the disadvantage that the circuit becomes saturated and the averaged output cannot be obtained correctly.

Purpose of the Invention The present invention eliminates the drawbacks of the conventional example described above, and aims to prevent erroneous knocking determination in the low rotation range and to accurately determine knocking from low rotation to high rotation. .

DESCRIPTION OF THE INVENTION In order to achieve the above object, the present invention provides a difference between the bias levels of the sensor signal and the averaging circuit to give a direct current offset to the two signals.

DESCRIPTION OF EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 4, 1 is a sensor, 2 and 3 are amplifiers, 4 is an averaging circuit that rectifies and averages the signal from amplifier 3, 5 is a comparator, 6 is a knock determination section, 7 is an ignition timing control section, and 8 is an averaging circuit that rectifies and averages the signal of amplifier 3. pickup coil, 9 a waveform shaping circuit, 10 an amplifier, 1
1 is the ignition coil.

12 is a bias circuit.

Next, the operation of the above embodiment will be explained. Sensor 1 is a detector that detects the pressure or vibration in the cylinder of the engine, and if knocking occurs, it will detect 5 to 12 KH accordingly.
A knocking-specific signal having a characteristic frequency within the range of z is converted into an electrical signal.

The amplifier 2 is an amplifier for amplifying the sensor signal, and if the sensor 1 is a non-resonant type sensor, a selective amplifier with bandpass characteristics is used as the amplifier 2. One of the sensor signal outputs from the amplifier 2 is input to the comparator 5, and the other is amplified by the amplifier 3, rectified and averaged by the averaging circuit 4, and provides a reference signal for determining knocking.

The comparator 5 compares the sensor signal output with a reference signal, and outputs a pulse signal when the sensor signal output is thick.

The knock determination unit 6 counts the pulse signals output from the comparator 5, and determines that knocking occurs if the pulse signal exceeds a predetermined number of times.
A non-king determination signal is output to the ignition timing control section 7. The ignition timing control section 7 calculates a retard control amount from the knocking determination signal and the pickup signal, and outputs an ignition timing signal. The pickup coil 8 is a converter that detects basic ignition timing, which is generally determined according to negative pressure and centrifugal force.

FIG. 5 shows a part of the electrical circuit of the above embodiment. As shown in FIG. 5, the amplifier 2 is an operational amplifier 21. resistance 2
2.23.24. It is composed of a capacitor 25.

The amplifier 3 is an operational amplifier 31. Resistance 32.33.34.
It is composed of a capacitor 35. In addition, the averaging circuit 4
is an operational amplifier 41° diode 42. Resistance 43. A rectifier circuit consisting of a capacitor 44 and a resistor 45. capacitor 4
It is composed of an integrating circuit consisting of 6. Also, bias circuits J2//i operational amplifiers 121, 122 . Resistance 123.
It is composed of 124°, 125.126. Above amplifier 2
The output of the operational amplifier 122 of the bias circuit 12 is applied as a bias to the amplifier 3 and the averaging circuit 4, and the output of the operational amplifier 121 of the bias circuit 12 is applied as a bias to the amplifier 3 and the averaging circuit 4. Bias level of the above amplifier 2 (
Va) and amplifier 3. The bias level (V6) of the averaging circuit 4 is calculated by the following equations.

However, R, , R,2, R,, R, are respective resistances]
23. ] 24.125.126 resistance value, ■cc
is the power supply voltage.

As is clear from equation (1), the bias level ■α of the amplifier 2 is always biased lower than the bias level ■h of the amplifier 3. Furthermore, by applying a bias level V, 6 to the bias of the averaging circuit 4, even if the level of the sensor signal is low, the reference signal that is the output of the averaging circuit 4 is smaller than the sensor signal output, as shown in FIG. Both are larger by the bias level difference (Va-Va). Therefore,
Even when the sensor signal is small, if a bias level difference is appropriately provided, it is possible to avoid erroneously determining knocking due to noise generated in engine pressure or vibration. FIG. 6 shows its operation. In FIG. 6, A is a sensor output signal and A2 is a reference signal. As shown in FIG. 6, by having a difference in bias level, erroneous determination of knocking can be prevented.

In the embodiments shown in FIGS. 4 and 5, the bias setting is performed at the input stage of the amplifiers 2 and 3, but the bias setting may be performed at the output side of the amplifiers 2 and 3 as shown in FIG.

Further, in the embodiments shown in FIGS. 4 and 5, the bias level difference is constant, but FIG. 8 shows an embodiment in which this bias level difference is changed depending on the engine speed. In this embodiment, the rotational speed is detected by the rotational speed calculation circuit 13 based on the signal from the pickup coil 8, and the bias setting is changed by the bias circuit 12 based on the signal. In this way, the bias setting can be finely controlled depending on the rotational speed, making it possible to accurately determine knocking.

Furthermore, in the embodiments shown in FIGS. 4 and 5, the amplifier 3. Although a difference is given to the bias level between the averaging circuit 4 and the amplifier 2, a difference may be given to the bias level between the averaging circuit 4 and the amplifier 2.

Effects of the Invention As described above, the present invention provides an appropriate difference in the bias level of the sensor signal and the reference signal obtained by amplifying and averaging the sensor signal, thereby preventing erroneous determination of knocking due to noise, especially at low rotation speeds. This has the advantage of preventing the occurrence of knocking and making it possible to accurately determine knocking.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional knocking control device, Figure 2 is a block diagram of a conventional knocking control device.
FIG. 3 is an explanatory diagram of the operation of the same device, and FIG. 4 is a block diagram of another embodiment of the knocking control invention in one embodiment of the present invention. 1...Sensor, 2...Amplifier, 3...Amplifier, 4...
...Averaging circuit, 5.Comparator, 6.Knock determination section, 7.Ignition timing control section, 8.Pickup,
9... Waveform shaping circuit, 10... Amplifier, 11...
Ignition coil, 12...bias circuit.

Claims (2)

[Claims] (1) A sensor that detects the pressure in the engine cylinder or the engine vibration, an amplifier that amplifies the output of this sensor, an averaging means that amplifies and averages the output of this amplifier, and an output of the amplifier and the above A comparator that compares the output of the averaging means, a determining section that determines knocking based on the comparison result of this comparator, and a control section that controls ignition timing based on the determination result of this determining section, A non-king control device characterized in that the bias level of the means is greater than the bias level of the amplifier. (2) The knocking control device according to claim 1, wherein the bias level difference between the amplifier and the averaging means is changed in accordance with the engine speed.