Patent ID: 8613226

Claim:
An ultrasonic flow meter comprising: a first ultrasonic sensor and a second ultrasonic sensor, each of the first ultrasonic sensor and the second ultrasonic sensor transmitting and receiving a plurality of ultrasonic waves of different frequencies, the first ultrasonic sensor disposed on a side of a flow channel in which fluid flows in a flow direction, the second ultrasonic sensor disposed on an opposite side of the flow channel from the first ultrasonic sensor, the second ultrasonic sensor disposed downstream of the first ultrasonic sensor in the flow direction; a volume-flow operation portion ordering the first ultrasonic sensor and the second ultrasonic sensor to transmit and receive one of the plurality of ultrasonic waves alternately, the volume-flow operation portion calculating a propagation time difference of the one of the plurality of ultrasonic waves between the first ultrasonic sensor and the second ultrasonic sensor and calculating a volume flow of the fluid based on the propagation time difference; a temperature operation portion analyzing signals output from the first ultrasonic sensor or the second ultrasonic sensor that receives the plurality of ultrasonic waves and calculating a temperature of the fluid corresponding to a humidity of the fluid based on an analyzing result; a pressure operation portion analyzing signals output from the first ultrasonic sensor or the second ultrasonic sensor that receives the plurality of ultrasonic waves and calculating a pressure of the fluid based on an analyzing result; and a correction operation portion correcting the volume flow calculated by the volume-flow operation portion with the temperature calculated by the temperature operation portion and the pressure calculated by the pressure operation portion, wherein each of the first ultrasonic sensor and the second ultrasonic sensor includes a plurality of transmitting elements, and each of the plurality of transmitting elements transmits an ultrasonic wave of a different frequency.