Apparatus for determining the combustion quality of a fuel

Claim 1

IN A SINGLE-CYLINDER TEST ENGINE FOR CONDUCTING A TEST OF THE COMBUSTION QUALITY OF A MOTOR FUEL, THE ENGINE PERFORMING NO USEFUL WORK AND HAVING A REPETITIVE OPERATING CYCLE, THE IMPROVEMENT COMPRISING MEANS FOR GENERATING A COMBUSTION-PROCESS SIGNAL INDICATIVE OF THE COMBUSTION PROCESS OF THE FUEL IN THE ENGINE, THE SIGNAL CONTAINING A LOW-FREQUENCY COMPONENT AND, WHEN DETONATION OCCURS, A HIGH-FREQUENCY COMPONENT, SAID LOW-FREQUENCY COMPONENT HAVING A PEAK AMPLITUDE WHICH, WHEN DETONATION OCCURS, IS A FUNCTION OF THE INTENSITY OF THE DETONATION AND SAID HIGH-FREQUENCY COMPONENT OCCURRING AT A TIME WHICH IS A FUNCTION OF THE TIME OF OCCURRENCE OF THE DETONATION, MEANS FOR FILTERING THE COMBUSTION-PROCESS SIGNAL TO PRODUCE A LOW-PASS FILTERED SIGNAL CONTAINING SAID LOW-FREQUENCY COMPONENT AND A HIGH-PASS FILTERED SIGNAL CONTAINING SAID HIGH-FREQUENCY COMPONENT, AND GATING MEANS RESPONSIVE TO THE HIGH-PASS FILTERED SIGNAL FOR PERFORMING THE OPERATION OF GATING THE LOW-PASS FILTERED SIGNAL WHEN DETONATION OCCURS TO PASS AS AN OUT-