SU581431A1 - Electronic tachometer - Google Patents

Description

one

The invention relates to the technique of electrical measurements of non-electric quantities and can be used to measure the speed of rotation of two-stroke two-cylinder engines,

Known electronic tachometers connected to ignition systems and containing waiting multivibrators with a measuring needle device

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A known electronic tachometer is connected to the ignition system through a limiter, the response level of which is adjusted depending on the type and quality of the ignition system in order to eliminate the influence of slow-damping oscillations on the triggering of the waiting multivibrator 31,

The disadvantages of this tachometer are the need for adjustment and the impossibility of using it in two-cylinder engines to control the operation of each of the ignition systems.

The purpose of the invention is to ensure control of the serviceability of the ignition system of two-cylinder engines.

The goal is achieved by the fact that the trigger is inserted into the tachometer with separate inputs connected to

signal level limiters, and the trigger output is connected to the input of the waiting multivibrator via a differentiating circuit.

The drawing shows the structural scheme of the proposed tachometer.

A tachometer contains a signal level limiter 1 (for example, a voltage divider, a maximum amplitude limiter with a constant threshold, etc.), trigger 2 with separate start (W-trigger), differentiating circuit 3 (for example, differentiating circuits connected by its own inputs to the trigger outputs, and outputs through dividing diodes to the multivibrator input), standby multivibrator 4, measuring device 5 of direct current (for example, a voltmeter)

The trigger changes its state by the arrival of one of the first half waves of the corresponding polarity contained in the ignition voltage. The form of the ignition voltage at subsequent points in time, the presence of a bounce of the contacts of the chopper does not affect the state of the trigger, since the voltage will die out and the bounce will stop before the next ignition time. Polarity of the first pulse

Ignition voltage is also not affected by the readings, since in the future there is a half-wave of another polarity, with which the trigger is triggered if the polarity of the first pulse does not correspond to that required for the trigger. A change in the amplitude of the pulses does not affect the readings, since there is a limiter at the input.

In the event of a malfunction of the elements (though one of the ignition systems (capacitor breakdown, breaker failure, malfunction of the ignition transformer primary winding), the amplitude of the ignition pulses is significantly reduced or becomes equal to zero. In this case, the trigger can be stopped so that be used to control the ignition system according to zero readings of the device when the engine is running.

The trigger voltage after differentiation triggers a waiting multi-vibrator, the constant component of the pulses of which is directly proportional to the number of revolutions developed by the engine per unit time. The indicated component is measured using a switch instrument graduated in revolutions performed by the engine crankshaft per unit of time.

The proposed device can be used in conjunction with electronic locking systems.

Claims (2)

1. Salomatin V.I. Contactless gauges of linear and angular velocities, M., 1974, p.39, 41, 43. 2. T1 of the USA 3811089, cl. 324-170, 14.05.74. 3 Sinelnikov A. Two devices avtolyubitel, in Sat. To help the radio amateur, vol. 36, M., 1970. p. 2 31.