Patent ID: 9304022
Filing Date: 2016-04-05
CPC Classification: G01F

Claim Text:
1. A flow rate measuring device comprising: a first transducer and a second transducer disposed in a flow path through which fluid to be measured flows, and for transmitting/receiving an ultrasonic signal; a transmitter for driving the first transducer and the second transducer; a switching part for switching transmission/reception between the first transducer and the second transducer; an amplifier for amplifying a signal received by the first transducer and the second transducer; a reference comparator for comparing between an output from the amplifier and a reference voltage; a reference-voltage setting part for setting the reference voltage to be used for comparison in the reference comparator; a determining part for determining an arrival time of the ultrasonic signal based on an output of the reference comparator and the output of the amplifier; a timer for calculating a propagation time from the transmission to the reception of the ultrasonic signal based on the arrival time determined by the determining part; a controller for calculating at least one of a flow velocity and a flow rate of the fluid to be measured according to the propagation time calculated by the timer; and a reference-voltage changing part for changing the reference voltage to be set in the reference-voltage setting part, wherein the reference-voltage changing part changes the reference voltage according to an amplification degree employed in the amplifier.