Patent GB-624879-A (GB)
Abstract: 624,879. Ignition systems. SMITS, W. B. Oct. 8, 1946, No. 30065. Convention date, Nov. 1, 1945. [Class 7 (iv)] In a low tension electrical ignition system for use with internal combustion engines comprising a generator for the generation of electrical impulses, e.g., a magneto or an induction coil fed through an interrupter from a battery, a condenser which is periodically charged by the generator and a spark gap, e.g., a low tension spark plug through which the condenser can be discharged directly, there is provided an electromagnetic switch or electro-magnetic throw-over switch that is actuated by, or in constant predetermined time relation with each electrical impulse, which switch after the condenser has been charged by the impulse, connects the condenser directly to the spark gap, the condenser being prevented from discharging back through the generator by an air gap. A battery 1 supplies a circuit consisting of the primary winding 2 of an autotransformer type induction coil, the coil 3 of an' electro-magnetic switch and cam operated 'circuit breaker contacts 5. When the circuit breaker contacts 5 are made the upper electro-magnetic switch contacts 7 are closed, or depending upon the position of the adjusting screw 8, spaced apart a small distance by virtue of the attraction between the armature 6, and the core of the coil 3 ; under which conditions the armature return spring 10 is extended. When the circuit breaker contacts 5 are opened, a high tension impulse is generated in the secondary 9 of the induction coil, which charges the main condenser 11, either directly through the electro-magnetic switch upper contacts 7, or the air gap formed by these contacts. At the same time as circuit breaker contacts 5 open, so the circuit through the electro-magnetic switch coil 3 is broken, causing the spring 10 to return the armature 6 to the de-energised position, thereby opening the upper contacts 7 and closing the lower electro-magnetic switch contacts 12. Simultaneously with the above, the rotary contact of a distributer 13 is arranged to touch one of the fixed contacts; and as a result, the main condenser 11 discharges across the electrodes of a sparking plug. The foregoing connections may be modified by shunting the electro-magnetic switch coil 3 across the induction coil primary winding 2 or by placing it in series with the induction coil secondary winding 9 or by utilising an induction coil with electrically separate primary and secondary windings. In another modification the main condenser 11 is made to discharge across a low tension sparking plug only, whilst the remaining plugs, which are of the usual high tension type, are supplied in the normal manner from the induction coil secondary winding 9 via the distributer, which latter is of the " jump spark " type. In a further modification; the induction coil primary winding is used at the same time to operate the electro-magnetic switch, thereby enabling the separate coil to be dispensed with. The Specification as open to inspection under Sect. 91, comprises also a further modification in which the armature 6 of the electro-magnetic switch may be operated mechanically by a member driven synchronously with the circuit breaker cam or magneto, which latter may replace the battery 1 and induction coil 2, 9. This subjectmatter does not appear in the Specification as accepted.