Patent GB-747060-A (GB)
Abstract: 747,060. Ignition systems. BENDIX AVIATION CORPORATION. March 29,  ' 1954 [April 17, 1953; April 17, 1953; Sept. 29, 1953], No. 9179/54. Class 7(4) In an ignition system fed from a source of energy including a storage condenser 22, Fig. 1, comprising a sparking circuit having a. hold-off gap 32 and an igniter gap 28 connected in series across the condenser, means is provided for rendering the gap 32 conductive to the charge on the condenser 22 when, this charge attains a given voltage below the normal spark-over voltage of the gap 32, the means comprising a control circuit connected to the condenser and including a triggering electrode 35 adjacent the hold-off gap, a second condenser 26 and means, such as a control gap .24 and a transformer 25. 36, for controlling a partial discharge of the storage condenser 22 at the given voltage into the second condenser 26 to create a discharge across the triggering gap to ionize the hold-off gap 32. IGNITION SYSTEMS The system is energized by a battery 10 and/or any other suitable source of energy which actuates a vibrator 18-21 in the primary winding 16 of a transformer, the secondary winding 17 of which is connected through one or more gaseous tube or selenium rectifiers 23 to the storage condenser 22 which may be shunted by a resistance 22<SP>1</SP>. A filter 14 may be inserted between the battery and winding 16. In parallel with the condenser 22 is a circuit comprising the sealed control-gap 24, the primary winding of the transformer 25, 36 and the condenser 26, preferably shunted by a resistance 27. A second parallel circuit is made up of the low-tension sparking plug 31 in series with the electrodes 33, 34 of the gap 32; the triggering electrode 35 is connected in series with the secondary winding of the transformer 25, 36 to the electrode 33. The transformer 16, 17, which may incorporate an air gap in its core, is designed to operate on the knee of the magnetization curve. The rectifiers may be dispensed with if the energy source is capable of charging the storage condenser by a single impulse or otherwise in such a manner that the condenser is not permitted to discharge back into the charging circuit. In a modification, the battery is replaced by a magneto 40, Fig. 2, the centre of the secondary winding .of which is earthed 44 whilst rectifiers 41, 42 are connected with the ends of the winding so that the condenser 22 is incrementally charged thereby; one set of rectifiers may be dispensed with. The energization of H.T, sparking plugs 51 is determined by a circuit breaker 48, 50 rather than the control gap; the circuit from the threeelectrode spark-gap 32 may be same as that of Fig. 1 but is preferably as shown and includes the plug 51, a transformer 53, 54 and a small condenser 52 shunted by a resistance 55. In another modification, the control gap 24, Fig. 3, is directly connected to the triggering electrode 35 which is joined by a surface-discharge spark-gap 36 to the spark-gap electrode 33. The surface-discharge gap 36 is preferably sealed in with the other electrodes of the sparkgap 32. In another modification, the embodiments of Figs. 2 and 3 are combined. In a modification of the Fig. 1 arrangement the control gap is connected directly in series with the condenser and the triggering electrode of the spark gap, the input and triggering electrodes of which latter are bridged by a resistance. In a final modification, the above arrangement of the resistance is combined with the Fig. 2 circuit. A distributer may be used with any of the foregoing embodiments. OPERATION The storage condenser 22, Fig. 1, is charged by a series of pulses until at a predetermined voltage the gap 24 breaks down and permits a partial discharge of the condenser 22 into condenser 26 to fully charge the latter, and through transformer 25, 36 to ionize the gap between electrodes 33. 34. The condenser 22 discharges the remainder and major portion of its energy through the gap 32 and the plug 31. Some of the charge in condenser 26 may at the same time discharge via the gap 32 and the plug 31; any residual charge on this condenser is dissipated in the resistance 27. When the gap 33, 34. Fig. 2, is ionized, the initial flow of energy into the condenser 52 through the primary winding of the transformer 53, 54 induces a high voltage in the secondary winding and thereby ionizes the sparking-plug gap so that the remainder of the charge on condenser 22 creates a high-energy discharge at the plug: the major portion of the charge on condenser 52 will discharge through the plug at the same time. Upon the initial discharge of the storage condenser 22, Fig. 3. the surface-discharge gap 36 becomes effective as the spark gap 24 is ruptured and the second condenser 26 is charged; the discharge across gap 36 ionizes the gap between electrodes 33, 34 so that the main discharge of the storage condenser takes place therethrough to energize the lowtension sparking-plug 31. In the Fig. 1 modification the resistance carries the initial discharge of the storage condenser into the second condenser but the major part of the discharge required to charge the latter takes place across the gap between the electrodes bridged by the resistance, thereby ionizing the main sparkgap to enable the system to function as previously described.