| 摘要 |
PURPOSE:To enable a handy and safe measurement without requiring a special equipment mounted on the rotary or non-rotary parts by determining the speed of the engine from an explosive sound thereof. CONSTITUTION:A microphone 1 brought close to an exhaust tube or the like. Explosive sound signals collected and converted to voltage are amplified with an amplifier 4, undesired noises excluding explosive sounds are removed with a filter 5 and the signals are rectified with a rectifier 6 to obtain a pulse signal corresponding to the explosive sounds of the engine. The signals are inputted into an engine rotational speed computing circuit comprising a reference time pulse oscillator 7, a gate circuit 8, an arithmetic amplifying section 9 and a selection switch 10 for setting a value varied depending on the engine specifications and the results of the required computation are indicated on a digital display 11a and on an analog display 11b. |
