IGNITION SYSTEM FUNCTION The function of the ignition system is to produce a spark in the engine cylinder towards the end of the compression stroke. In a four-stroke engine, a spark should occur in each cylinder after two revolutions of the crankshaft, whereas in a two-stroke engine a spark in each cylinder is required every revolution of the crankshaft. Thus, for instance, in a 6-cylinder 4 stroke engine running at 5000 r.p.m., the number of sparks required per minute will be 15000 and these have to be timed very accurately. REQUIREMENTS OF AN IGNITION SYSTEM 1. Spark at the plug electrodes must be regular and synchronously timed with respect to the cylinder-piston position at all speeds and loads on the engine. 2. The spark should be sufficiently strong so as to start ignition of the charge. Since lean air fuel mixtures are less conductive, they require higher ignition voltages. Thus on modem emission-controlled engines that use lean-mixtures, higher-voltage ignition system is requir...
A study material for Automobile Engineering, MAEE, MMV, Diesel mechanic and Mechanical students. (Both KGCE & NCVT)