SU937759A1 - Contact-free device for controlling i.c. engine electronic ignition system - Google Patents

Description

The purpose of the invention is to increase the reliability of starting the internal combustion engine by increasing the steepness of the control pulse front.

The goal is achieved by the fact that in a contactless device for controlling an electronic ignition system of an internal combustion engine containing a generator of high-frequency oscillations on a transistor and a magnetically controlled block with a switching element, the magnetic circuit of the magnetically controlled block is made on a ferrite of the W-shaped form and is equipped with an extreme at least three windings: mi, one on each rod of the-shaped magnetic circuit, with the windings on the extreme rods included counter, the windings of the magnetically controlled block, Magnetic cores located at the extreme rods are included in the emitter and base circuits of the transistor, and the emitter windings are shunted by a diode.

The duration of the pulse of the block - generator depends mainly on the time constant of the transformer and the capacitance of the capacitor included in the base circuit of the transistor.

In order to obtain the required pulse length of a dmittern, the negative feedback winding has a significantly smaller number of turns than the base winding of a positive feedback, and has a very small effect on the time constant of the transformer.

FIG. 1 is a schematic diagram of the device; Fig. 2 shows the principal construction of a transformer on a W-shaped core with windings and switching plates.

The device contains a generator transistor 1, a magnetically controlled variable-coupling unit 2, formed by windings 3-6 on the magnetic core 7 and a switching element 8 located on the sensor rotor, combined with the engine camshaft. Winding 3 is included in the collector circuit of the transistor, the positive feedback winding is included in the base circuit of the transistor, negative feedback winding 5 is connected to the emitter circuit of the transistor, the load winding 6 is needed to obtain

the output pulse power sufficient to start the thyristor, the capacitor 9 of which, together with the inductance of the transformer, determines the required output pulse duration, the resistor 10 providing the generator operation mode, the diode 11 with a short time for setting the direct voltage, connected in parallel with the emitter winding, ensures the reliability of a periodic excitation of the generator and obtaining a high steepness of the rise of the front, diode 12 connected in parallel to the collector

winding magnetically controlled unit 2, designed to eliminate the negative surge of the output pulse and eliminate the occurrence of high-frequency oscillations, the output stage 13 switches the ignition coil.

In the initial state, the generator is in a static (unexcited) position due to the fact that the magnetic fluxes of the windings A and 5 are directed oppositely. When the engine shaft rotates, the generator is periodically excited. The switching element 8 alternately closes with a permissible gap the magnetic circuit between the rods with windings 3 and C of the magnetic core 7, as a result of which positive feedback is provided. An avalanche-like process of increasing the collector current arises, the diode 11 is unlocked and shunt the winding 5, which contributes to the weakening of the negative feedback and a sharp increase in the leading edge of the generated pulse. On the output winding 6 a rectangular pulse of positive polarity with steep edges is formed. After that, the generator returns to its initial state until the next approach of the switching element 8. Duration # 1 of the pulse generated by the generator does not depend on the transit time of the switching element 8 over the magnetic core 7 and is determined by the circuit parameters (mainly the transformer time constant and capacitor capacitance).

The pulse duration is chosen twice as long as the thyristor is turned on.

In the next approach, the switching element 8 to the rods with the windings 3 and the process repeats and the generator again produces a pulse to control the thyristor ignition system.

The proposed non-contact device provides a powerful output with a steep front directly from the generator sensor for controlling, for example, thyristor ignition without an additional driver,

Claims (1)

1. USSR author's certificate No. 5EVE7, cl. F 02 P 7/10, 1968, (prototype (. 5 V Y "g. F 7 6 V 1