GB580694A - Improvements in or relating to ignition systems for internal combustion engines - Google Patents

Abstract

580,694. Ignition systems. BENDIX AVIATION CORPORATION. May 5, 1944, No. 8585. Convention date, May 12, 1943. [Class 7 (iv)] In an ignition system for an internal combustion engine a magneto 5 provides sparks for normal running and a booster system is provided for starting, the booster comprising a trembler induction coil 31 supplied with current from a battery 33 and arranged so that the inductive surge following breaking of the coil circuit is applied to. the primary winding of a transformer, the secondary of whch is in series with one of the spark gaps. In the application to a 9-cylinder engine the coil 9 of the magneto is associated with the usual contact breaker 11 operated by a cam 12 driven from the engine. The contact breaker 11 is connected to the ring 14 of the distributor, the ring being connected through the rotary arm 18 to segments 16, each segment is connected through a lead 21 to the primary 22 of the spark coil and the secondary coils 24 are each connected to a spark plug 25. A switch 26 may be provided to. earth the magneto primary to stop the engine. Each primary circuit 21 is provided with a resistance to dissipate residual energy after sparking has occurred preferably a resistance of about 16 ohms may be included in each primary winding 22. The booster coil 30 is controlled by a starter operated switch 34 and has contacts 35 normally closed by a spring 38. A fuse 39 may protect the coil 31. If the timing of the booster sparks can be the same as the magneto the coil 31 may be directly connected to the distributor ring 14, the contact breaker 11 then serving to earth the coil output except when the points are open. Preferably separate retarding means are provided for the booster sparks by the inclusion of a second circuit breaker 40 controlled by the cam 12, or by another cam. A resistance 41 is provided to limit the flow through the magneto coil 9 and may have a value of about 3 ohms in conjunction with a coiling inductance of 5 milli-henries. In operation switch 34 is closed and the trembler coil 31 operated. During this operation contacts 11 are periodically opened and shortly afterwards the contacts 40 close at the required sparking time. This causes a surge from the coil 31 to flow through the distributor to spark coils 22 to cause sparking at the plugs. When the engine starts switch 34 may be opened automatically or otherwise. In a modification, Fig. 2, the main circuit breaker is employed for timing the booster impulses and a switch 44 is opened after starting to prevent the magneto from being earthed through the booster coil. In another modification the switch 44 is replaced by a solenoid operated relay swich.