RU2111379C1 - Thyristor-plasma ignition system for internal combustion engine - Google Patents

Abstract

FIELD: mechanical engineering; internal combustion engines. SUBSTANCE: system has ignition coil with first terminal of secondary winding connected through distributor with first terminals of group of spark plugs whose second terminals are connected to common bus, twinned voltage converter first output source of which being connected by one pole to anode of thyristor switch and to series-connected reservoir capacitor and first terminals of ignition coil primary winding and second output source being connected by its second poles to common bus. System has also pulse shaper connected by input to breaker contact and by output, to control input of thyristor switch. To minimize equipment losses second pole of first output source, second terminal of ignition coil primary winding and second leadout of thyristor are connected to common bus, and second terminal of ignition coil secondary winding is connected to first pole of second output source of voltage converter. EFFECT: enhanced reliability of operation. 1 dwg

Description

 The invention relates to plasma ignition systems for internal combustion engines and can be used to ignite lean fuel mixtures.

 For effective ignition of the working mixture, it is desirable to use a pulse with a high rate of voltage (current) rise. At the same time, this pulse should have a sufficiently long duration for effective afterburning of the ignited mixture. These requirements are contradictory, since a wide pulse cannot have sharp edges, and a pulse with sharp edges cannot be wide. This is due to the inability to reduce the ratio of the inductance of the windings of the high voltage coil to the leakage inductance and to reduce the stray capacitance of the high voltage circuits below a certain level.

 It is also known that for effective ignition of the working mixture, it is advisable to ionize it before ignition [1]. Since the degree of ionization is determined by the magnitude of the ionizing voltage and the duration of the preionization process, and the magnitude of the ionizing voltage is limited, it is advisable to increase the ionization time while reducing the ionizing voltage.

 Known combined plasma ignition system, providing preionization of the working mixture in the spark gap by applying high voltage candles to the electrodes during the time preceding the appearance of the main ignition pulse [2].

 The disadvantage of this system is the lack of afterburning voltage on the spark plug electrodes after the main pulse, which negatively affects the completeness of combustion of the working mixture and the concentration of harmful components in the exhaust gases.

 Also known is a combined plasma ignition system that provides both preionization of the working mixture and its afterburning at the end of the main pulse [3].

 The disadvantage of this system is the complexity of the circuit, determined by the presence of two independent ignition systems (spark and plasma).

 The closest analogue (prototype) of the claimed device is a plasma ignition system [4]. It contains a control unit including a chopper, a pulse shaper and a voltage switch, a voltage converter, an accumulation unit, a spark generating thyristor switch, a recovery element, an ignition coil, a distributor, and a group of spark plugs. In the system [4], unlike other known analogues, the above-mentioned disadvantages are overcome.

However, the system [4] has the following fundamental disadvantages:
1) the presence of a high voltage (about 3000 V) at the midpoint of the windings of the ignition coil, on all circuits of the thyristor switch and on the output circuits of the pulse shaper, which is associated with the need for galvanic isolation between these circuits and the common bus and greatly complicates the circuit and design of the claimed device;
2) the bulky design of the ignition coil (in particular its magnetic circuit) due to the flow of a constant component through its primary winding;
3) the circuit and design are additionally complicated due to the presence of a recovery element and a voltage switch.

 All this is the reason for the large hardware costs when creating a plasma ignition system according to the patent [4].

 The aim of the present invention is to minimize hardware costs.

 The proposed thyristor-plasma ignition system for internal combustion engines contains an ignition coil, the first terminal of the secondary winding of which is connected through the distributor to the first terminals of the group of candles, the second terminals of which are connected to a common bus, a dual voltage converter, the first of the output sources of which is connected by one pole to the anode thyristor key and to the series-connected storage capacitor and the first terminal of the primary winding of the ignition coil, and the second output source to the second pole is connected to a common bus, and a pulse shaper connected by the input to the contact of the chopper, and the output to the control input of the thyristor key.

 This goal is achieved in that the second pole of the first output source, the second terminal of the primary winding of the ignition coil and the second terminal of the thyristor switch are connected to a common bus, and the second terminal of the secondary winding of the ignition coil is connected to the first pole of the second output voltage conversion source.

 A comparative analysis with the prototype shows that the claimed device is distinguished by a new inclusion of the main elements of the circuit (ignition coil, thyristor switch, dual voltage converter), as well as the absence of a recovery element and a voltage switch. Thus, the claimed device meets the criterion of "novelty." The newly introduced set of features is essential, since it allows to minimize the circuit and design of the thyristor-plasma ignition system due to the separation of the primary and secondary windings of the ignition coil; the use of one storage capacitor connected directly to the primary winding of the ignition coil; connecting a thyristor key with one pin to a common bus; the use of a pulse shaper with only one output (for controlling the thyristor) with the connection of its second output via a chopper to a common bus. In this case, the recovery element and the voltage switch turned out to be unnecessary, as well as the DC component was removed from the primary winding of the ignition coil. This allows us to conclude that the claimed device meets the criterion of "significant differences". The claimed technical solution meets the criterion of "inventive step", since it is for specialists explicitly not follows from the prior art. At the same time, the claimed technical solution is “industrially applicable”, since it is designed for the widest use in the automotive industry, shipbuilding and aircraft manufacturing, as well as in all types of vehicles where internal combustion engines are used.

 The drawing shows a structural diagram of the inventive device. The first terminal of the secondary winding of the ignition coil 1 through the distributor 2 is connected to the first terminals of group 3 of candles, in which the second terminals are connected to a common bus. The input of the dual voltage converter 4 is connected to a ± 14 V DC source. The first pole of the first output 5 of the converter is connected to the anode of the thyristor switch 6 and a series-connected storage capacitor 7 and the first terminal of the primary winding of the ignition coil, in which the second terminal is connected to a common bus. The second pole of the first output of the converter and the other terminal (cathode) of the thyristor switch are connected to a common bus. The control input of the thyristor switch is connected to the output of the pulse shaper 8, in which the input is connected to the contact of the chopper 9. The second terminal of the secondary winding of the coil is connected to the first pole of the second output 10 of the converter, in which the second pole is connected to a common bus.

 The practical implementation of the claimed device is as follows. As elements 1, 2, 3, and 9, typical ignition coils, a distributor, a group of spark plugs, and a chopper are used that are available in any internal combustion engine (for example, in an automobile). As element 6, in particular, the thyristor T106-10 was used, and as element 7, a capacitor of the type K73-17-0.47 μF was used.

 As block 4 can be used, for example, the voltage Converter shown in Fig. 1 p. 11 of the book [5], in which an additional winding with a multiplication circuit is introduced on the transformer T1 (to obtain 3500 V). And as an element 4, a pulse shaper in the same fig. 1 book [5], including resistors R5, R6 and capacitors C2 and C.

 The claimed thyristor-plasma ignition system for internal combustion engines works as follows. In the initial state, when the ignition is turned on, one of the four contacts of the distributor 2 (take, for example, a four-stroke engine) is closed in the same way as the contact of the chopper 9, from the output 10 of the converter 4 to one of the spark plugs of group 3 through the secondary winding of the coil 1 and the distributor 2 receives a high-voltage voltage, insufficient for the breakdown of the spark gap, but quite sufficient for ionization of this gap and its environs. At the same time, the capacitor 7 is charged through the primary winding of the coil 1. At the moment of opening the contacts of the chopper 9 through the former 8, the thyristor 6 opens and the capacitor 7 is discharged to the primary winding of the ignition coil 1. At the same time, a voltage sufficient to breakdown the spark gap of the spark plug develops. Since the spark gap has been ionized up to this point, the breakdown voltage is much lower than in a typical ignition system. After the end of the pulse on the primary winding of coil 1 (the duration of this pulse is limited by the discharge time of the capacitor 7) in the spark gap, in contrast to the usual case, the voltage of the additional output 10 of converter 4 remains, insufficient for the breakdown of the spark gap, but quite sufficient to maintain the working flame mixtures. At the moment of opening the contact in the distributor 2, the voltage at the contacts of the spark plug disappears and the charge of the capacitor 7 begins, since the thyristor 6 is closed by the reverse half-wave of the main ignition pulse of the coil, as in conventional thyristor ignition systems. After the distributor 2 closes the next contact, the corresponding candle is connected to the high-voltage voltage at the output 10 of the converter 4 through the secondary winding of the coil 1 and the process is repeated.

 The technical and economic efficiency of the claimed device consists in minimizing the hardware costs of a thyristor-plasma ignition system by means of a fundamentally new approach to constructing a circuit in which galvanic isolation between its main elements and a common bus is not required, there is no constant component in the primary winding of the ignition coil, and restoration is not required voltage element and key.

Sources of information
1. Matskerle J. Modern economical car (trans. From Czech.). - M.: Mechanical Engineering, 1987, p. 199.

 2. Description of the invention to patent SU N 1838665. N.V. Chistikhin. Combined electronic ignition system. B.I. N 32, 1993.

 3. Description of the invention to patent RU N 2019727. O.I. Isakov. Combined plasma ignition system for internal combustion engines. B. I. N 17, 1994.

 4. Description of the invention to patent RU N 2000465. V.D. Gerasichkin, V.D. Domnin, V.M. Puzeev. Plasma ignition system for internal combustion engines. BI N 33 - 36, 1993.

 5. Sinelnikov A.Kh. Electronic devices for cars. - M .: Energoatomizdat, 1986, p. 11.

Claims (1)

 Thyristor-plasma ignition system for internal combustion engines, containing an ignition coil, the first terminal of the secondary winding of which is connected through the distributor to the first terminals of the group of candles, the second terminals of which are connected to a common bus, a dual voltage converter, the first of the output sources of which is connected by one pole to the anode thyristor switch and to the series-connected storage capacitor and the first terminal of the primary winding of the ignition coil, and the second output source is the second is connected to the common bus line, and a pulse shaper connected by an input to the contact of the chopper, and by an output to the control input of the thyristor key, characterized in that the second pole of the first output source, the second terminal of the primary winding of the ignition coil and the second output of the thyristor key are connected to the common bus and the second terminal of the secondary winding of the ignition coil is connected to the first pole of the second output source of the voltage converter.