Detonation analyzer for piston engine

Claim 1

Apparatus for analyzing the detonation vibrations within each cylinder of an internal combustion engine having a rotating crankshaft, pistons connected thereto and spark plugs energized by a magneto for cyclically igniting the air-fuel mixture within each of said cylinders, said apparatus comprising: a multiplicity of vibration sensors, one of said sensors being in contact with each cylinder of the engine being analyzed, each of said sensors providing an output signal that is an electronic replica of the vibrations going on within said cylinder; a switch for selectively sampling the output of one of said multiplicity of vibration sensors; first electronic circuitry means connected to the output of said switch means, said electronic circuitry means serving to amplify and filter the signal from the selected vibration sensor whereby the frequency band associated with the detonation phenomenon are amplified more than other frequencies; an oscilloscope having a visual display and including a signal input terminal and a synchronizing pulse input terminal, said signal input terminal being supplied by the output from said first electronic circuit means; and second electronic circuitry means for generating a wave train of synchronizing pulses for injection into the synchronizing pulse input terminal of said oscilloscope, said second electronic circuitry means including: a pulse generator connected to the output of said magneto and providing a conditioned output pulse each time said magneto ignites an engine cylinder, a stepping counter having as many outputs as there are cylinders in the engine, said counter receiving conditioned pulses from said pulse generator at the engine firing rate, a timing source producing a reset pulse in coincidence with the attainment of top-dead-center by the piston of number one cylinder of said engine, said reset pulse being used to return said stepping counter to its initial state, and a switch for selecting one of the outputs of said stepping counter, said selection being for the purpose of obtaining a synchronizing pulse input for said oscilloscope, said synchronizing pulses being coincident with the passing of ignition pulses to the cylinder spark plugs.