SU490944A1 - Ignition system for internal combustion engines - Google Patents

Description

one

The invention relates to devices used in electrical equipment for internal combustion engines.

Electronic thyristor ignition systems are known in which there is a stabilized onboard converter.

The disadvantage of such voltage converters is relatively low efficiency. Converter due to losses in the stabilization scheme and large size.

The purpose of the invention is to eliminate these disadvantages.

This goal is achieved by the fact that the stabilization unit of the converter is made as an additional winding of a transformer connected to a chain of a resistor and a tunnel diode, parallel to the latter is connected the input of the transistor, the output of which is connected to the primary winding of the converter.

To ensure the temperature stability of the voltage on the filling capacitor, the diameter of the additional winding wire is chosen from the ratio

A 1 / A

dn u in

where - the diameter of the wire additional winding; du is the diameter of the primary wire;

/ t is the peak current of the tunnel diode; / p is the current of the transformer's nerve winding.

In order to ensure adjustment in order to eliminate the scatter of the parameters of individual elements, it is necessary to take the diameter of the auxiliary winding wire somewhat larger.

Diagram of the proposed ignition system shown in the drawing.

The ignition system consists of a key transistor 1, a transformer of converter 2, which contains the primary (cumulative) winding 3 n additional winding 4, as well as winding 5 for charging circuit for capacitor 6 and turning on the thyristor 7, switching circuit 8 of key transistor 1 from chopper 9, diode 10, resistors 11 and 12 and capacitor 13, threshold circuit for switching off the key transistor 1 after reaching a predetermined energy in the primary winding 3. The stabilization unit is formed by an additional winding 4 connected to the tunnel nomu diode 14 through resistor 15, through which can be varied to garner the primary winding inductance energy. Co} 1 capacitor 6 through the thyristor 7 is connected to the ignition coil 16. The key transistor I is maintained in the open state by transistors 17 and 18. Parallel to the tunnel diode H

The input of the additional transistor 19 is connected, the output of which is connected in parallel to the primary winding 3 of the converter. Capacitors 20 and 21 improve the noise immunity of the converter.

The ignition system works as follows.

When the contacts are opened, the chopper 9 turns on the key transistor 1 due to the charging current of the capacitor 13. At the same time, the thyristor 7 is turned on from the secondary inductance and discharges the capacitor 6 to the ignition coil 6. The key transistor 1 is kept open by positive feedback zi from the primary winding 3 through transistors 17 and 18. The current in the primary winding 3 increases according to a linear law. According to the same law, the current in the winding 4 rises, since the voltage on the tunnel diode 14, if the current through it does not exceed the peak value, is low and the transistor 19 is closed. The ratio of the currents in the windings 3 and 4 is determined by the resistance of the windings and the resistor 15, since due to an equal number of turns of the windings e. D., driven in them, is the same and is compensated mutually on the tunnel diode 14. When the current in the winding 4 reaches the peak current of the tunnel diode 14, the voltage on it increases sharply, the transistor 19 opens, charges the capacitor 20, and the voltage at the emitter of the transistor 17 becomes larger than at its base, the transistor 17 is closed, the positive feedback circuit is broken, and the key transistor 1 is closed. The energy stored in the inductance coil of the secondary winding 1 charges the capacitor 6. In this case, one converter operation cycle ends.

The capacitor 20 increases the gain of the transistor 17 at the moment it is turned on, reduces the effect of ripples on the power supply circuit and creates a time delay, since after the transistor 19 is triggered, the capacitor 20 is quickly charged and maintains the transistor 17 for some time in the closed state.

Capacitor 21 increases noise immunity and is found experimentally due to the absence of the influence of impulse noise on the operation of the converter. In the process of switching on the converter from the chopper 9, the capacitor 21 has little effect, since the capacitor 21 is quickly charged through the capacitor 13 when the contacts of the chopper 9 are opened.

When the temperature of the inductor changes, the resistance of the windings 3 and 4 will change. If the windings are made of copper, then when the temperature changes from -40 ° C to - | -80 ° C, the resistance of the windings changes by more than ± 25% relatively normal. To ensure temperature stability, the current through the tunnel diode 14 must be determined by the active resistance of winding 4, which is made of the same material as the power winding. In this case, the active resistances of the windings will vary by the same relative value, and since the active resistance of the windings is inversely proportional to the square of the diameter of the wire, the diameter of the additional winding wire to obtain thermal stability should be determined from the above-mentioned cooTnoHie.

Subject invention

An ignition system for internal combustion engines containing a transistor voltage converter, the primary winding of the output transformer of which is connected to the collector circuit of the key transistor, and the secondary winding to the charging capacitor charge circuit and to the control thyristor

a stabilization unit, characterized in that, in order to increase the efficiency, the stabilization unit is made in the form of an additional winding of the specified transformer connected to the chain consisting of a resistor and

tunnel diode, and in parallel with the latter is connected the control circuit of the auxiliary transistor, the power circuit of which is connected to the primary winding of the output transformer. -L.i