Patent ID: 6012338
Filing Date: 2000-01-11
Classification: G01F,G01P

Abstract:
An ultrasonic flow velocity measuring apparatus including two transducers arranged to form a certain angle to a flow velocity direction in a section intended to measure the flow velocity, in which two transducers transmit and receive an ultrasonic beam in turn to each other to enable an ultrasonic transmitting time to be measured and then to compute a flow velocity, wherein:two transducers are connected to a transducer switching portion,the transducer switching portion is connected to an outputting amplifier,the outputting amplifier is connected to a frequency modulation oscillator for generating a continuous wave of a predetermined modulation frequency,the frequency modulation oscillator is connected to a one shot multivibrator for oscillating a given frequency pulse to operate the frequency modulation oscillator, the one shot multivibrator is connected to a control square pulse generating portion to be operated at a given period,the control square pulse generating portion is connected to the transducer switching portion and an output switching portion for controlling a switching operation,the outputting amplifier amplifies an output signal from the frequency modulation oscillator, the transducer switching portion enables the output signal from the outputting amplifier to be inputted into any one of the transducers and then the output signal from the corresponding transducer to be inputted into a receiving amplifier,the outputting switching portion is connected to the receiving amplifier for switching the output signal from the receiving amplifier to apply to a frequency discriminator,the outputting switching portion is connected to an attenuator for damping an output voltage of the outputting amplifier,the outputting switching portion is connected to the frequency discriminator to detect a frequency modulation moment,the frequency discriminator is connected to a pulse shaping portion to share the output of the frequency discriminator into a square pulse,the pulse shaping portion is connected to a time interval measuring portion to measure a time difference between two pulses from the pulse shaping portion, andthe time interval measuring portion is connected to a flow velocity arithmetic-logic processing unit to compute the flow velocity.