ENGINE AUTOMATIC QUALITY CONTROL SYSTEM THROUGH NOISE ANALYSIS AND DIAGNOSTIC

An automatic production test system for quality control and diagnostics of automotive gasoline engine is presented. The equipment, based on a DIGITAL microprocessor PDP 11/23, analyzes and processes vibration signals as induced by running engines during a defined test bench cycle. The vibration signals are coming from only one accelerometer placed on the engine crankcase wall. With this equipment, abnormal vibrations are detected and mechanical defects like valve rattle, connecting rod knock and crank rumble, related to various engine components, identified. The hardware signal treatment and reject philosophy employed in the microprocessor software have been developed on the basis of correlations with the observed defect's characteristics during inspection and repair operations. The system is operating in the workshop quality inspection room and the quantitative obtained information is in good agreement with the engine behaviour.