AVERAGE AIR FLOW RATE DETECTING APPARATUS BY KARMAN'S VORTEX STREET TYPE AIR FLOW RATE SENSOR

摘要

PURPOSE:To detect the average of pulse cycles with high precision during large flow rate by calculating the average cycle or the average air flow rate at every detection of a pulse cycle more than a prescribed time after counting a prescribed number or the smaller number than that of pulse by Karman's vortex street. CONSTITUTION:The pulse output of a Karman's sensor 3 in which an output signal (a) becomes 1 at every generation of Karman's vortex is counted by microprocessor 9. Whether the prescribed cycle is exceeded or not is discriminated in case = the prescribed number Nmax, and the average pulse cycle is calculated in case = said cycle. The prescribed number Nmin in exceeded or not is discriminated in case = the number Nmax, the average air flow rate is obtained in case =Nmin, whether the prescribed cycle is exceeded or not is discriminated in case =Nmin. The average pulse cycle is calculated in case = said cycle, and the average air flow rate is calculated switchedly in case = said cycle. Further, in calculation of the average pulse cycle, a constant in prescribed limit is added to Nmax, the averaging processing is performed to prepare next processing.