SU1679416A1 - Spark duration meter - Google Patents

Abstract

The invention relates to electrical measuring technology and can be used to measure the duration of electric discharge processes in spark plugs, electrical gaps and devices of similar purpose. The purpose of the invention — to improve the accuracy of measuring high-frequency signals — is achieved by introducing a two-threshold discriminator level 2, a peak detector 3 and an element 1/1 6. In addition, the meter contains a current sensor 1, a discriminator level 4, a one-shot 5, a block 7 of the account. 2 Il.

Description

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The invention relates to electrical measuring equipment, in particular, devices for measuring the duration of fast pulsed processes, and can be used to measure the duration of electric discharge processes in spark plugs, electrical discharges and devices of similar purpose.

The purpose of the invention is to improve the accuracy of measuring high-frequency signals.

FIG. 1 shows a block diagram of a spark duration meter; in fig. 2 - timing diagrams, explaining the principle of operation.

The spark duration meter contains a current sensor 1, a two-threshold discriminator 2 level, a peak detector 3, a discriminator 4 level, a single vibrator 5, element 6, a counting unit 7, the output of current sensor 1 connected to the input of a two-threshold discriminator level 2, the output of which is connected with the input of the peak detector 3, the output of the latter is connected to the input of the discriminator 4 level and to the input of the one-vibrator 5, the output of the discriminator 4-level is connected to the first input of the And 6 element, the second input of the element And 6 is connected to the output of the single-vibrator 5 and AND 6 is connected to the input of block 7 of the account.

The meter works as follows.

A current sensor 1, for example, a measuring current transformer, is connected in series with a spark gap (candle), in which spark discharges occur at a certain frequency. The shape of the current curve through the candle is shown in FIG. 2a. Before the start of the spark discharge, an insignificant current of the so-called preparatory stage of the discharge flows through the candle (section O-ti). Next, a spark stage of discharge develops (the t-i-ta area), the duration of which is measured by the device. The analog signal from current sensor 1 is fed to the input of a two-threshold discriminator level 2, in which this signal is compared with a positive and negative reference value (discrimination levels). If the magnitude of the input signal is greater than the positive discrimination level or less than the negative discrimination level, then a logical 1 signal is generated at the output of the two-threshold discriminator of Level 2 (FIG. 2 b).

Consequently, a two-level two-level discriminator performs a direct conversion of the measured

input signal to a digital signal. The levels of discrimination are selected on the basis of statistical data on the value of the transition current of the preparatory stage.

spark discharge in semiconductor spark plugs. Peak detector 3 delays for a certain time the slice of each pulse coming from the output of the two-threshold discriminator of level 2 to fill the gaps between them (Fig. 2c). Consequently, at the output of the peak detector 3, a single pulse is formed with a time slice cut off.

In the discriminator of 4 levels, the signal is compared with a predetermined reference value, above which a logic level 1 appears at its output. ). The pulse duration at the output of the discriminator level 4 (Fig. 2 g) is longer than

sparks on the value of At (time of decay of the signal at the output of the peak detector 3 from the logic level 1 to the value of the reference voltage of the discriminator 4 level). The one-shot 5 is triggered on the signal front,

coming from the output of the peak detector, and gives a single pulse of a logical O with duration At. In element 6, the signal of the one-vibrator 5 is subtracted from the signal coming from the output of the discriminator 4 level. At the output of element 6, an impulse is obtained whose duration is equal to the duration of the spark (Fig. 2e). The measurement of the generated pulse is carried out by a known method in block 7 of the counting.

Claims (1)

The invention The spark duration meter containing a current sensor, a level discriminator, one-shot, counting unit, characterized in that, in order to increase the accuracy of measuring high-frequency signals, a two-threshold level discriminator and the peak detector, element I, the output of the current sensor is connected to the input of the two-threshold level discriminator, the output of the peak detector is connected to the input of the level discriminator and to the input one-shot, the output of the discriminator level is connected to the first input of the element And, the second input of the element And is connected to the output of the one-shot, and the output of the element And is connected to the input of the counting unit. Levels of discrimination Urobsh discrimination ii i h 2