ACTIVE NOISE CONTROL UNIT FOR AUTOMOBILE

PURPOSE: To easily generate sound energy which is large enough to absorb an air suction noise under noise reduction control which generates a sound wave interfering with the air suction noise in an air suction system. CONSTITUTION: A frequency component of suction pulsation is extracted based on the...

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Bibliographische Detailangaben
Hauptverfasser:	TOMIZAWA NAOMI, TOKI SHUICHI, GOKAN YOSHIAKI
Format:	Patent
Sprache:	eng
Schlagworte:	ACOUSTICS ACOUSTICS NOT OTHERWISE PROVIDED FOR BLASTING ENGINE PLANTS IN GENERAL GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL HEATING LIGHTING MACHINES OR ENGINES IN GENERAL MECHANICAL ENGINEERING METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL MUSICAL INSTRUMENTS PERFORMING OPERATIONS PHYSICS SOUND-PRODUCING DEVICES STEAM ENGINES TRANSPORTING VEHICLES IN GENERAL VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISEPROVIDED FOR WEAPONS
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Beschreibung
Zusammenfassung:	PURPOSE: To easily generate sound energy which is large enough to absorb an air suction noise under noise reduction control which generates a sound wave interfering with the air suction noise in an air suction system. CONSTITUTION: A frequency component of suction pulsation is extracted based on the output of an air flow meter (S1 and S2), and phase processing is performed for the frequency component (S3). Then a cycle (f) and an amplitude Pw that a sound wave outputted from a speaker is expected to have are calculated based on the extraction result (S4). The cycle (f) and amplitude Pw are converted into the cycle fp and duty ratio Duty of a pulse signal used for electric feeding control over a voice coil respectively (S5). Here, the pulse having the cycle fp and duty ratio Duty is generated through the clocking of a timer (S6) and the power supply to the voice coil is controlled with the pulse signal.