Patent GB-608324-A (GB)
Abstract: 608,324. Igniting burners. NAPIER & SON, Ltd., D., and RAMSAY, F. R. F. Feb. 20, 1946, No. 5255. [Class 75(iii)] [Also in Groups XXVII and XXXV] Any ignition system, which can be used for igniting burners, comprises an ignition coil or magneto, an auxiliary spark-gap in the circuit of its secondary winding and means for coupling a spark-plug circuit to the secondary circuit so that the highfrequency current resulting from an auxiliary gap spark will ionise the sparkplug gap and the spark-plug circuit is coupled to the primary circuit so as to supply to the spark plug circuit a relatively low-tension discharge following up the high-frequency current to develop heat in the spark-plug gap. As shown, Fig. 1, an ignition coil A has its secondary A<2> shunted by a condenser G and connected through a spark-gap E to the primary F<1> of a high-frequency transformer F. The secondary F<2> of the highfrequency transformer is connected at one end to a spark plug H and at the other end to the primary A' of the coil A. When the gap of the spark plug is ionised by high-frequency current from the transformer F a relatively low-tension discharge takes place from the primary of the coil A through the spark plug. The primary circuit of the coil includes a battery B contact-breaker C and condenser D. An inductance J may be included in the primary circuit to increase the intensity of the discharge. Alternatively the primary of the coil A may be arranged as an autotransformer the contact-breaker being connected to the intermediate terminal of the autotransformer and the end being connected to the secondary of the high-frequency transformer. In this case a condenser may be connected between this end of the autotransformer and the battery side of the contact-breaker. In a modification, the high-frequency transformer is dispensed with, the spark-gap is connected directly to the terminal of the spark-plug and a condenser connected between this terminal and earth. In this case a high-frequency choke is connected between the spark-plug and primary of the coil. In another modification, Fig. 3, a trembler coil A\ A<2> having a split core A<5> is employed. The secondary A<2> is connected to a condenser G and spark-gap E and a high-frequency autotransformer L supplies the impulses to the spark-plug. A condenser D in parallel with the contactbreaker C is arranged in circuit with the autotransformer and a second condenser may be in parallel with the spark-plug. The autotransformer may be replaced by a simple high-frequency coil. In Fig. 5, the ignition coil is replaced by a magneto A', A<2>. The secondary F<2> of the highfrequency transformer F<1>, F<2> is provided with a switch Q so that it can either be connected to the magneto primary A', or to earth. In the latter case the system functions as a known high frequency ignition system. A distributer P connects the secondary to spark-plugs H. The employment of the switch Q enables the ignition system to operate with both highfrequency and low-tension discharges at the spark-plugs or as a normal highfrequency system. The well known types of high-frequency ignition system may be converted to work according to the invention by connecting a lead from the primary of the coil or magneto to the secondary of the high-frequency transformer. The high-frequency transformer may be of a series of flat spirals of copper strip placed coaxially to give a low resistance of about one fifth of an ohm. The spark-gap may be of a form in which one electrode is formed as a cup and the other is situated within it. The gap may be mounted coaxially with the high-frequency coil. The low-tension current may be supplied to the spark-plug by a battery.