摘要 |
<p>A system is disclosed for monitoring the quality of combustion in a cylinder of a spark ignition internal combustion engine having an ignition coil connected by a high tension lead to the spark plug of the cylinder. The system comprises an isolator (22) arranged in the high tension lead (24) in series with the gap (28) of the spark plug for allowing spark energy to be transmitted to the spark plug from the coil and isolating the spark plug from the coil after a spark has been generated. A circuit (34) monitors the decay of the voltage on the spark plug by leakage of charge through the burnt gases in the combustion chamber after each spark has been extinguished. The isolator (22) comprises a pair of spaced electrodes arranged in a sealed chamber between which electrodes an arc is struck when spark energy is transmitted through the isolator to the spark plug gap.</p> |