FI58203B - ELECTRONIC STROCH SCREW FOER EN MOTORS TAENDSTIFT - Google Patents

Description

| Vff £ Vl [B] (11) ADVERTISEMENT, ULKA.SU COOAT

f @ SA LJ '} UTLÄGGNI NGSSKMFT 3 ° ^ υ C Patcntt' * y ", nne tty IC 12 1220 ^ Pa tent ci '.' dj? La t ^ ^ (S1) K» .ik.3 / int.a .3 P 02 P 3/08 FINLAND —FINLAND (21) P »t * mftak * im» -IWt * n »ökA> n | 1956/73 (22) H» k * ml * cloud * An * eknlr> ( * d «f 18.06.73 * f '* (23) ΑΙΙαιρβΜ — Glfclfh« t * dtg l8 Qg ^ (41) Tullut JulklMktl - Bltvlt affwtllg ^ 73 P »tanttl- j. Registry Board (44) Nthtfvik, lFMnon„ kuU | ultaliim

Patent and refereed employment in the public sector 29 03 50 (32) (33) (31) Pyr * «« y «TuoikAu * —b ^ ih priority 23

Italia-Italien (IT) fifthAU A / 72 (71) Safe Electronic Systems S.A., Mauren, Liechtenstein (Ll); c / o Alessandro Villa, Chiasso, C.so S. Gottardo 33, Switzerland-Switzerland (CH) (72) Enio Di Cesso, Milan, Mario Totti, Milan, Italy-Italy (lT) (7 * 0 Oy Heinänen Ab ( This invention relates to an electronic circuit for supplying electrical current to an engine spark plug.

Several types of electronic capacitive discharge current circuits are known which control the spark ignition system of an engine. One disadvantage of such circuits is due to their high input current, which is in the range of about 3-5 A during operation and which leads to overheating of some electrical components in the circuit. Such components are, for example, a transformer, transistors and a thyristor which form part of the same circuit. Such overheating, especially at higher engine speeds, results in a deterioration of the output power and may, for a long time, interrupt the operation of the ignition circuit.

More specifically, the electronic capacitive discharge circuit, 2 5 8 2 O 3, which supplies current to the spark plug of the engine, consists of a power unit which provides a high voltage (in the range of about 2 ^ 0-450 V) direct current. A thyristor and a capacitor are connected in parallel at the output of the power unit, while this capacitor is connected in series with the high-voltage coil to supply the same current to the spark plugs of the engine.

Throughout operation, there is a capacitor-coil unit And apparently also the output of the power plant repeatedly short-circuited for very short times. This results in a capacitor discharge on the one hand and an increase in the current flowing through the power unit on the other hand, which is due to its short circuit. Due to the structure of already known circuits, both the components of the power plant and the thyristor in question overheat due to this current increase. j i

In the circuit supplying the spark plug to the engine, I is first obtained

positive Voltage spike (used for ignition) j When voltage is discharged to the high voltage ignition coil. This positive j peak is immediately followed by a negative voltage spike, which has no use in ignition. Attempts have been made to recover this negative j Voltage in the capacitive discharge circuit by using a rectifier which forms part of the power plant; but in this way only a small fraction of this voltage has been recovered, i i 'i

An additional disadvantage of known circuits is that they cannot be used! in engines running at very high speeds. In fact, they can only be used in I motors operating at 6000-8000 rpm, because at higher speeds the same circuits are easily damaged beyond repair, as the power consumption increases as the speed increases.

The main object of the present invention is to provide an electronic capacitive discharge circuit which supplies the spark plug of an engine and has a very low power requirement (e.g. about 1.6-1.7 A at 6000 rpm) even at high engine speeds.

Another object is to provide a circuit as defined above in which, when a thyristor is short-circuited, the current flowing through the power unit decreases (instead of increasing or even remaining constant) compared to the current flowing through the same device; when this is directly connected to the battery and the motor is not running,! i.e. when the ignition key is in place in the instrument panel and in the ignition position) 58203 while the engine is not running. This means that the i.v.cnom of the power unit and the electrical components connected to it with the circuit is practically non-existent while the engine is running.

It is an object of the invention to provide a circuit in which the negative voltage peak in the high voltage coil can be almost completely used to recharge the discharged capacitor much more efficiently than has hitherto been possible in already known circuits and thus to obtain a very low power requirement.

It is an object of the invention to provide a circuit which can be used in "motors with electronic tachometers" and which is able to operate correctly even when the motor is running at a very high speed, e.g. 12,000 rpm or more.

Yet another object of the invention is to provide an ignition circuit which, even in tropical climates and unusually harsh and prolonged operating conditions, is not subjected to overheating and thus retains its operating characteristics almost unchanged.

toininfl, I

The electronic circuit according to the invention for driving the spark plugs of a motor comprises a supply booster connected to a capacitive discharge circuit having a thyristor and a capacitor and

i its child can be connected to the high voltage coil of its electrical circuit,; through which energy is supplied to the spark plugs. Said supply amplifier is connected to a direct current source comprising an assembly of two resistors and one capacitor to which the bases of transistors forming part of the same supply power are connected. In addition the circuit according to the invention comprises an inductor placed between the positive terminal of said direct current source and a circuit breaker supplying energy to the spark plug. The circuit according to the invention 1 is characterized in that a resistor is connected in series with said direct current source, in parallel with which at least one diode is connected, that the ratio of the primary winding of the transformer to the reactor winding is in the range of about 1.6: 1 to 2.7: 1 and that said resistor and at least one diode are arranged to assist the operation of said assembly of two resistors and one capacitor during periods of time where the thyristor of the capacitive discharge circuit is non-conductive to reduce the input energy during said periods of time and to prevent the circuit from overheating.

58203

It is preferable to use a diode to connect the assembly formed by the polarization capacitor of said resistor and the bases of the transistors and a wire connected to the positive terminal of the direct current source of the supply booster.

The invention is disclosed in the following description by means of its most preferred embodiment, using the accompanying drawing, which shows a wiring diagram for an electronic circuit. Both the explanation and the drawing are given by way of example without limitation.

The circuit shown in the drawing consists of a supply booster connected to a capacitive discharge circuit. Said supply booster is shown in the drawing below the dashed line and the two terminals 1 and 2 can be connected to a low voltage direct current source, e.g. a battery, as all cars are equipped with. In particular, terminal 1 is designed to be connected to the positive terminal of said battery.

The capacitive discharge circuit is shown above the broken line at the top of the drawing, and its input and output lines, indicated by reference numerals 3 and 4, respectively, can be connected to the high voltage coil terminals of the motor circuit to which the circuit is to be connected.

The supply amplifier consists of an amplifier transformer whose primary winding 5 is connected to transistors T1 and T2, respectively, and a reactance winding 6 to ignite an oscillation, which results in an alternating voltage being generated in the secondary winding 7. At this voltage, ] a bridge, a capacitor C3 is charged, which forms part of a capacitive discharge circuit. The polarization of the bases of the power amplifier transistors T1 and T2 is effected by resistors R1 and R2 and a capacitor C1 through the reactance winding 6 of the transformer.

A resistor R3 is connected in series with the supply line 1 of the power amplifier leading to the positive terminal of the direct current source formed by the battery, with which two diodes D5 and D6 are in turn connected in parallel.

The assembly of parts R3, D5 and D6 plays a very important role in assisting the assembly of parts R1, R2 and C1 when the thyristor (forming part of the circuit under consideration and the operation of which will be explained later) is non-conductive, thus reducing the power requirement of the supply booster n. 70-100 mA; thus, the high power demand of the feed booster blade is prevented on its part during their continuously repetitive cycles when it is short-circuited. In this way a considerable result is obtained, i.e. overheating of the circuit, in particular transistors T1 and T2, combustion of the transformer, etc., etc. is prevented.

The supply amplifier circuit also includes a capacitor C2 which acts as an interference filter at both the input and output ends and a diode D7 connected between the DC supply lines or between the whole.

The presence of said diode D7 in the circuit is not essential for efficient operation of the circuit; however, it has been found that when diode D7 is in the circuit, better efficiency of transistors T1 and T2 is achieved, especially at high temperatures. Especially when the temperature in the circuit rises too high, e.g. when the temperature exceeds 80 ° C, the operating characteristics of the same circuit - which would otherwise suffer - remain unchanged due to diode D7. Indeed, as the temperature rises, the resistance of the diode D7 decreases, resulting in an increase in the polarization voltage at the bases of transistors T1 and T2 with an increase in temperature when transistors T1 and T2 are made non-conductive by a thyristor (explained in more detail below). Thus, the current flowing through transistors T1 and T2 is reduced, whereby the harmful j

overheating is prevented. In any case, it is good to point out that I

the presence of diode D7 is only necessary in exceptional cases, e.g. when the circuit is operated at very high ambient temperatures, high discharge frequencies and high input powers.

The capacitive discharge circuit shown at the top of the drawing is configured to discharge energy from the supply booster and stored in the capacitor C3 through the output lines 3 and 4 to the high voltage side of the engine ignition system to which the electric circuit is connected. which is operated by its control electrode, to which an inverse or negative fundamental voltage (bias) of half the magnitude of the voltage supplied by the supply booster is applied.

Such a fundamental voltage for the thyristor control electrode is obtained by means of two resistors R4 and R5 and a capacitor C4.

The control pulse for the thyristor is obtained by the inductive action of the coil L, this coil being connected between the positive terminal of the supply voltage and ground G via a platinum tip or a switch belonging to a movable ignition distributor forming part of the motor power supply to which the electrical circuit is connected.

The positive pulse thus generated on the other side of the above-mentioned platinum tip or switch 8, which is generated due to the coil L at the moment when the tips are pulled apart, i.e. when disconnected, flows through the resistor R6, diode D8 and capacitor C5. to the control electrode, rendering the thyristor non-conductive, resulting in the discharge of capacitor C3.

The electrical gating of the thyristor occurs immediately at the end of the pulse transmitted by the coil L; such immediate action is effectively aided by the inverse fundamental voltage at the thyristor control electrode.

The circuit also includes a resistor R7 and a capacitor Co for electrically filtering and separating the low voltage used as the basic voltage for the thyristor and for supplying the coil L.

The same circuit also comprises a capacitor C7 and a resistor R8, which are already connected in series and are intended to attenuate overvoltage spikes in the high-voltage coil belonging to the motor power supply circuit when the capacitor C3 is discharged, thus preventing damage to the thyristor; at the same time promoting recharging of capacitor C3 via the bridge formed by diodes D1, D2, D3 and D4.

Finally, it should be mentioned that the capacitive discharge circuit also includes a resistor R9, as shown in the drawing.

5 8 2 0 3 7

By closing the circuit through which energy is supplied to the supply power supply, to an energy source which may be a low voltage source, such as a 12 V car battery, through terminals 1 and 2, said voltage is applied to the power supply transformer, base circuit components R1, R2 and C1 and transistors T1. and T2 through the primary winding of said transformer. The voltage traverses the assembly formed by the parts D5, D6 and R3, causing the supply amplifier to oscillate and produce the voltage required to charge the capacitor C3 at the output of the diode bridge D1, D2, D3 and D4.

As soon as the platinum tips 8 operate, i.e. when they are opened and closed, a pulse is sent to the thyristor, which thus becomes non-conductive and thus causes the capacitor C3 to discharge into the "high voltage side" of the motor supply circuit.

In particular, it should be noted that when the supply voltage is 12V at terminals 1 and 2 and germanium transistors T1 and T2 are used, the value of resistor R3 should be in the range of about 3-8 / 1 and preferably about 5-6A. Here it is good to note that it is possible to disconnect said resistor with three or more diodes, rather than with only two diodes D5 and D6, as in the drawing.

Again, based on the above assumption, the ratio of the speeds of the primary winding 5 and the reactive winding 6 of the transformer is in the range of about 1.6 / 1 to 2.7 / 1 and most preferably in the range of about 2/1 to 2.1 / 1. The value of resistor R2 with a fishing rod is about 22-56A. and most preferably about 33 Π. , while the value of resistor R1 is about 600-1200, most preferably about 8200. The value of capacitor C2 is in the range of about 1-8 pF and most preferably about 3-5.

The required good efficiency of the electrical ignition circuit can be achieved, even in the most difficult operating conditions and high ambient temperatures, only when the components of the electrical circuit shown have the above values and based on the assumption that the supply is 12 V and in particular that the components are D5, D6. and R3.

The inductance of the coil L, the existence of which is essential only when the motor to which the circuit according to the invention is connected is equipped with an electronic tachometer, but which is in any case useful by providing a high negative polarity thyristor lie, should be 58203 ο in the range of about 70-280 mH and most preferably about 180 mil. This coil winding should most preferably be of the bee or lattice type.

The value of resistor R8 should be in the range of about 200-800 / 7 and most preferably about 470/1 while the value of capacitor C7 should be in the range of 8000-30000 pF and most preferably about 22000 pF.

Finally, special mention is made of the feature that the thyristor receives a relatively large negative fundamental voltage due to the resistors R4 and R5 in the circuit. The thyristor is thus given a fundamental voltage equal to half the voltage applied to the feeder, which was assumed to be 12 V.

If, on the other hand, 12 V DC is applied to terminals 1 and 2 and when the transistors are of the silicon type, the value of resistor R3 should be in the range of about 0.05-8 fl and preferably n, 0.1-6 / 7 while resistor R1 should be in the range of n. 200-120011. , preferably 300-800 / 7 and a resistor R2 of about 10-56 0, preferably 15-33 / 7 · The inductance of the coil L should again be in the range of about 20-280 mH and preferably in the range of n.

70-180 mH.

Numerous and exhaustive experiments to which the circuit has been subjected have shown that all the points made in the preamble to this explanation have been fully achieved.

Claims (5)

9 PAT Η \ ΐ I REQUIREMENTS 58203 An electronic circuit for operating motor spark plugs, comprising a supply booster connected to a capacitive discharge circuit having a thyristor and a capacitor, which in turn can be connected to a high voltage coil of the electrical circuit through which energy is supplied to the spark plug, and a supply current comprising an assembly of two resistors (R1, R2) and one capacitor (C1) to which the bases of the transistors (T1.T2) forming part of the same supply amplifier are connected, and which electronic circuit further comprises an inductor (L) located on the positive side of said direct current source; between a terminal and a circuit breaker supplying energy to the spark plug, characterized in that a resistor (R3) is connected in series with said DC source, in parallel with which at least one diode (D5, D6) is connected, so that the primary winding and reactor winding hde is in the range of about 1.6: 1 to 2.7: 1 and that said resistor (R3) and at least one diode (D5, D6) are arranged to assist said assembly of two resistors C R1, R 21 and one capacitor (C1) operation during periods of time when the thyristor of the capacitive discharge circuit is non-conductive to reduce the input energy during said periods of time and to prevent the circuit from overheating. Electronic circuit according to claim 1, characterized in that a diode is connected between the positive terminal of said direct current source and two assemblies (R1, R2) and a capacitor (C1) to which the bases of the transistors (T1, T2) are connected. (D7), which increases the efficiency of said transistors, especially at higher temperatures. The electronic circuit of claim 1, wherein the voltage of the DC source is 12 V and wherein the transistors of the feeder are of the silicon type, characterized in that the value of the resistor (R1) is about 200-2000Π, the value of the resistor (R2) is about 10-56 / Ί, the value of the resistor (R3) is about 0.05-8 / 1 and the capacitance of the capacitor (C1) is about 1-8 piF. The electronic circuit according to claim 1, wherein the voltage of the direct current source is 12 V and wherein the transistors of the feeder are of the germanium type, characterized in that the value of the resistor (R1) is about 300-800/1, the value of the resistor (R2) is about 15 -33/2, the value of the resistor (R3) is about 0.1-6 / 2 and the capacitance of the capacitor (C1) is about 3-5 μF. 10 58203 Electronic circuit according to Claims 1, 3 and 4, characterized in that a coil (L) with an inductance in the range of approximately 70-1Θ0 mH is arranged between the positive terminal of the direct current source and the ignition switch. 11 58203 FATlMTnRAV