Flow meter device

摘要

In a flow meter device of the present invention, a time measuring section of the flow meter device includes a first counter which starts counting at a starting point of measurement of propagation time; and a second counter which starts counting at an end point of the measurement of the propagation time, and performs counting at a higher speed than the first counter. A propagation time TO is finally obtained by subtracting time Δt which is measured by the second counter and passes from the end point until the first counter counts up, from time T which is measured by the first counter and passes from a starting point until the first counter counts up after the end point. A flow calculating section calculates a flow with high accuracy using the propagation time TO. Thus, lower electric power consumption can be achieved, and accuracy of measurement of flow can be improved.

主权项

1. A flow meter device comprising:
first and second ultrasonic transmitters/receivers which are placed at an upstream side and a downstream side, respectively, in a measurement passage through which fluid flows; a transmission section that actuates the first ultrasonic transmitter/receiver to transmit a drive waveform; a reception section that detects the drive waveform propagated to the second ultrasonic transmitter/receiver, wherein the propagated drive waveform consists of a packet of waves having a plurality of zero-cross points; a time measuring section that comprises a first counter and a second counter counting at a higher speed than the first counter, wherein the first counter is activated to begin counting when the transmission section actuates the first ultrasonic transmitter/receiver, and the second counter is activated and deactivated to begin and end a counting operation repeatedly to perform multiple counting operations during a span of the wave packet such that in each of the counting operations the second counter is activated at a different one of at least some of the plurality of zero-cross points and deactivated at an end of a counting cycle of the first counter coming immediately subsequent to the corresponding one of the plurality of zero-cross points, and the time measuring section subtracts a time interval counted by the second counter during a respective at least some of the counting operations from a time interval counted by the first counter to an end of the corresponding one of the counting operations to obtain a plurality of propagation times for the propagated drive waveform; and a flow calculating section that calculates a flow rate of the fluid using an average of the plurality of propagation times obtained by the time measuring section.