Patent ID: 7082841

Claim:
An ultrasonic wave flowmeter, comprising: a transmitter for transmitting an ultrasonic wave signal; a receiver for receiving the ultrasonic wave signal which has been transmitted from the transmitter and has been propagated through a fluid; a reception detecting section for receiving an output of the receiver and detecting the ultrasonic wave signal; a delay section for receiving an output of the reception detecting section and outputting it to the transmitter so that the ultrasonic wave signal is transmitted again; a counter for counting the number of detections by the reception detecting section; a timer for repeatedly measuring a time period from the time when the transmission of the ultrasonic wave signal by the transmitter is started to the time when the counter reaches a predetermined value; a calculation section for calculating a flow rate of the fluid, based on an output of the timer; and a delay control section for controlling the delay section to change the delay time of the delay section each time the measurement by the timer is made.