Ignition advance corrector. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Automobile. Ignition

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Currently, many motorists are showing increased interest in electronic ignition timing devices (ECU) or octane correctors (OC), which allow 5 ... to fuels of various qualities. Existing circuit solutions have some disadvantages:

- the delay is made for a fixed period of time, which, at different revolutions of the motor shaft, corresponds to different SPDs [1, 2];

- when constructing delay circuits without a fixed SPD, their complexity increases significantly [3, 4, 5].

In view of the foregoing, we have developed a simple and effective OC, in which, at any engine shaft speed, the UOS remains constant. The block diagram of OK is shown in fig. 1. The basis of his work is the fact that the delay of the UOS is proportional to the period of rotation of the shaft. A sequence of pulses, in which, within certain limits, it is necessary to delay the positive front, is formed by a chopper and fed to the input of the circuit.

(click to enlarge)

In this case, the duration of the pause is used as a reference value, which is fixed using the reference frequency generator G1 and the reversible counter CT, which, at a low level at the input (±1), works to increase the count (accumulation of information), and if there is a high level at the same input - to decrease (reading the accumulated information). In the first case, the generator G1 works, and in the second, the generator G2 (and G1 is blocked). G2 frequency can be changed. If the G1 and G2 frequencies are equal, the SPD delay is 90°, therefore, to ensure a delay of up to 30°, it is necessary that the G2 frequency be three or more times higher than the G1 frequency. At the end of the count, when the counter has given all the accumulated information, a signal is generated at its output P, ​​which sets a high level at the output of the RS flip-flop, blocks the operation of the counter and is a delayed output signal. The circuit returns to its original state when a low level arrives at its input, which resets the RS flip-flop, and the cycle repeats.

Schematic diagram of OK and diagrams of its operation are shown in Fig. 2 and Fig. 3, respectively. At the input of the circuit, a low-frequency filter is installed on the elements R3, C3, which, together with cells DD1.1, DD1.4, containing Schmitt triggers at the input, eliminates the influence of the breaker contact bounce on the operation of the circuit. The G1 generator is assembled on DD1.3, DD1.2, R7, C2 and, to prevent overflow of the counters DD2, DD3 at low engine speeds, is set to a frequency of 1 kHz. The generator G2 is assembled on DD1.1, DD1.2, R4, R5, C1 and with the help of a variable resistor R4 can change its frequency from 3 kHz to 90 kHz, which provides adjustment of the UOZ from 30 ° C to 1 °, respectively. Counters DD2, DD3 are connected in cascade, which increased their total capacity to 256 bits.

Fig.2 (click to enlarge)

The counters first accumulate information about the duration of the closed state of the breaker contacts, and after they open, they read it. When the counters are completely reset, a short-term negative pulse appears at pin 7 of DD3, which, through DD4.3, switches the RS flip-flop assembled on DD4.2, DD4.4. At the inverse output of the trigger, a blocking signal of the counter DD2 is generated and, through DD4.1, R6, VT, an output delayed signal.

Details:

The K561TL1 microcircuit can be replaced with the K561 LA7, but in this case, after the low-pass filter, it is necessary to install a Schmitt trigger assembled according to any known scheme. Zener diode VD1 - any for a voltage of 5 ... 9 V. The KT972 transistor can be replaced with a pair of KT3102, KT815 (KT817). Capacitors C1, C2 must be selected of the same type or with the same TKE as close to zero as possible. The same applies to resistors R5, R7. In parallel with each microcircuit, it is desirable to install a ceramic capacitor with a capacity of 0,1 μF along the power buses, and in parallel with VD1, a tantalum electrolytic capacitor.

Setting

To configure the generators, you must install the frequency meter probe to pin 4 of the DD1 chip. After that, a low logic level should be applied to the input of the circuit and the resistor R7 should be selected so that the generator frequency is 1 kHz. After that, set the slider of the resistor R4 to the lower position according to the diagram, apply a high logic level to the input and select the resistor R5 so that the frequency counter reads 90 kHz, which corresponds to a delay of 1 °.

In the upper position of the R4 slider, the oscillator frequency should be about 3 kHz, which corresponds to an SPD delay of 300. If desired, this value can be changed up or down by changing the value of R4. After that, it remains to calibrate the scale of the resistor R4, which is installed on the control panel. It is desirable to shield the wires to it.

Literature

1. Kovalsky A., Frolov A. Prefix octane-corrector. Radio. - 1989.-№6.-C.31.
2. Sidorchuk V. Electronic octane corrector. Radio. -1989. - No. 6.-C.31
3. Bespalov V. OZ angle corrector. Radio. - 1988. - No. 5. - S. 17.
4. Arkhipov Yu. Digital ignition timing controller. Radio Yearbook.-M., 1991.-C129.
5. Romanchuk A. Octane corrector on CMOS chips. Radio amateur. -1994.-No.5.-C.25.

Authors: V. Petik, V. Chemeris, Energodar; Publication: N. Bolshakov, rf.atnn.ru

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