SU550994A3 - Electronic ignition system for internal combustion engine - Google Patents

Description

(54) ELECTRONIC IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE

Known thyristor ignition systems with an accumulation of energy in a capacitor, which is charged from the secondary winding of the charging transformer when the current flowing through its primary winding is interrupted, while the storage capacitor is discharged to the primary winding of the ignition coil when the control pulse is synchronized with rotation of the motor shaft to the thyristor 1. In such ignition systems, the duration of the spark discharge is insufficient, which reduces the reliability of ignition of the fuel mixture.

In order to increase the reliability in the proposed ignition system, the charging transformer is provided with an additional secondary winding connected via a blocking diode to the primary winding of the ignition coil.

When creating each ignition spark, when the current flows in the sensing winding by transferring energy to the primary winding of the ignition transformer, the head part of the spark formed by discharging the storage capacitor is stretched to the tail of the spark. At the same time, the costs of obtaining longer ignition sparks with insignificant losses of efficiency are practically not increased.

The core of the charge transformer is made with a gap.

With the required choice of the size of the air gap of the core of the transformer, the inductances of the secondary winding of the transformer, the primary and secondary windings of the ignition transformer, as well as the interelectrode gap in the spark plugs, the duration of the spark tail can be easily stretched 4-5 times compared with the duration the head of the spark, so that the ignition sparks take a duration of more than 1.5 ms, which makes it possible to ignite the compressed gas in the cylinder in almost all cases.

With the ignition sparks inductances of the primary and secondary windings of the ignition transformer chosen to obtain increased durations, the gear ratio for the required height of the spark head may be too small. Therefore, it is advisable that the primary winding of the ignition transformer is made of two partial windings that are connected in series with the secondary winding and one of which is connected to a storage capacitor so that to obtain an intense spark head, the storage capacitor is discharged only through this partial winding, and the other the partial winding is wrapped around the secondary winding of the charging transformer.

FIG. 1 is given an electrical circuit of the described ignition system; in fig. 2 is an oscillogram of a long-term ignition spark obtained by this system.

The sensing winding 1 of the charging transformer 2 with the iron core 3 is connected at one end through the ignition switch 4 to the positive pole of the battery, and the other through the collector-emitter junction of the transistor 5 and the feedback transformer 7 is connected to ground. The negative pole of the battery also sits on the ground. Resistance 8 connects the emitter of transistor 5 to its base, which is connected to sensor 9 control pulses. The secondary winding 10 of the feedback transformer 7 is also connected between the emitter and the base of the transistor. As a means of limiting the collector current at the maximum value, control thyristor 11 is used, the anode of which is connected to the base of transistor 5, and the cathode sits on the ground. In parallel, the control thyristor 11 is connected to a voltage divider with resistances, to the connection point of which the control electrode of this thyristor is connected so that the control thyristor 11 is turned on while the collector current of transistor 5 has a value at which the base current of the transistor creates a voltage on the divider sufficient to turn on the thyristor.

The secondary winding 12 of the charge transformer 2 is connected at its one end to the sensing winding 1, and the other end through diode 13 to the storage capacitor 14, the second lining of which is connected to ground via the primary winding of the igniter 15. The secondary winding 16 of the coil of the Igana 15 hall through the distributor feeds the spark plugs of the internal combustion engine. To discharge the storage capacitor 14 through the primary winding of the ignition coil, there is a thyristor 17, the anode of which is connected to the capacitor and the cathode sits on the ground. The firing electrode of the thyristor 17 is connected through a resistance to ground and, moreover, is connected to a control pulse sensor 9, which is controlled by a breaker 18 so that when the breaker contact opens, it issues an appropriate control pulse.

To create the sparks extended in time, the charging transformer 2 has an additional secondary winding 19, which, together with the sensing winding 1, forms a transformer. One end of the additional secondary winding 19 is connected to the ground, and the other through the locking diode 20 to the primary winding of the ignition coil 15. Primary winding of the ignition coil Consists of two series-connected partial windings (windings with tapping), and the connection point of both windings is connected to the storage winding to the capacitor 14, and the free end of the partial winding, not connected to the mass, through the locking diode 20 is connected to the additional secondary winding 19 so that the capacitor 14 is discharged through only one

the partial winding, and both the partial windings together with the locking diode 20 and the additional secondary winding 19 of the charging transformer 2, create through the mass a closed current circuit. Both partial windings are bypassed with a diode 21 to damp reverse oscillations.

If after the closing of the ignition switch 4 when the contact of the chopper 18 is open, a control impulse comes from the sensor to the base of transistor 5, then the transistor starts to conduct, and the battery flows through the sensing winding 1 of the charging transformer 2, collector-emitter

the transition of the transistor 5 and the primary winding 6 of the transformer 7 feedback. Due to the flow of a small current in the primary winding 6 of the feedback transformer, a current is induced in its secondary winding 10,

with which the transistor quickly becomes fully conductive, so that the current through the sensing winding 1 of the charging transformer quickly increases. The increase in current is determined by the air gap in

the core of the charge transformer 2 and the inductances of the sensing winding 1, the additional secondary winding 19, and also the primary winding of the ignition coil 15. Some of the perceived winding 1 is electric

energy is expended to energize the air gap, and a part is consumed by an electrical circuit consisting of the secondary winding 19, the diode 20, the primary winding of the ignition coil and ground. If the current through the sensing winding 1 reaches a force at which the base current creates a voltage drop across the thyristor divider 11 so large that the thyristor 11 opens, then transistor 5 is quickly brought into the locked state. The flow of current through the sensing winding 1 is interrupted, and the energy accumulated in the charging transformer is converted into voltage l; 400 V on the winding 12. The indicated voltage charges through the diode 13 accumulative

capacitor. When the contact is opened, the chopper 18 is triggered by a pulse from the control pulse sensor 9, the thyristor 17 is ignited and the storage capacitor 14 is discharged through the conductive thyristor to

part of the primary winding of the ignition coil 15, and in the secondary winding 16 a high voltage is induced, which in the ignition sparks creates an intense head part I {see FIG. 2). At the same time, with the help of a control pulse, the transistor 5 becomes

conductive, therefore, the current through the sensing winding 1 is interrupted. An increase in the current in the sensing winding of the charging transformer induces a current in the secondary winding 19, which flows further through the entire primary winding of the ignition coil 15 and creates tail section II (see Fig. 2) in ignition sparks.

The proposed thyristor ignition system showed satisfactory results. So, for example, in an experimental capacitor device for ignition with short-term sparks when charging a storage capacitor up to 400 V, with inductance of the primary winding of the ignition coil 10 mH, transmission ratio of the ignition transformer 1: 50, spark gap in the spark plugs 1 mm and gas pressure 10 MPa the duration of the sparks was 300 μs. The same thyristor ignition system with an additional winding of a 19 charge transformer 2 provided a spark duration of 1050 μs.

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Claims (2)

1.Electronic ignition system for an internal combustion engine containing a charging transformer, the primary winding of which is connected via a transistor interrupter to the power source, and the secondary one via a rectifier with a storage capacitor, a thyristor, an ignition coil and elements of control of the maximum value of the thyristor control current, so that, in order to increase reliability, the charging transformer is provided with an additional secondary winding connected through a locking diode to the primary winding of the cat shki ignition. 2. A system according to claim 1, characterized in that the charging transformer core is made with a gap. The source of information taken into account in the examination: 1. US patent No. 3677255, cl. 123-148 E, 1972. (fl / S.l