×

Vortex flowmeter

  • US 5,736,649 A
  • Filed: 08/22/1996
  • Issued: 04/07/1998
  • Est. Priority Date: 08/23/1995
  • Status: Expired due to Term
First Claim
Patent Images

1. A vortex flowmeter comprising:

  • a vortex shedder provided in a flow path;

    an ultrasonic transmitter and an ultrasonic receiver disposed on both sides of said flow path in a portion downstream of said vortex shedder and spaced apart from said vortex shedder by a predetermined distance, said transmitter and receiver being offset from each other along a flow direction of said flow path and said transmitter emits ultrasonic waves as consecutive pulses of a regular interval;

    a memory means for storing first data representative of a relation between generation frequency of Karman vortices generated by said vortex shedder and a flow rate of fluid flowing in said flow path and second data representative of a relation between (a) a difference of an ultrasonic wave propagation time relative to the reference propagation time when the flow rate of fluid flowing in said flow path is substantially zero; and

    (b) the flow rate of the fluid flowing in said flow path;

    a first calculation means for determining the generation frequency of the Karman vortices on the basis of a detection signal obtained from said ultrasonic receiver and for determining the flow rate on the basis of the first data;

    a second calculation means for measuring the ultrasonic wave propagation time between said ultrasonic transmitter and said ultrasonic receiver, for determining a difference between the ultrasonic wave propagation time when the flow rate of the fluid is substantially zero and the measured ultrasonic wave propagation tie and for determining the flow rate of the fluid flowing in said flow path from the difference between the ultrasonic wave propagation times on the basis of the second data; and

    an output switching means for switching an output so that, when the flow rate of the fluid is greater than a predetermined value, the flow rate of the fluid determined by said first calculation means is outputted and, when the flow rate of the fluid is smaller than the predetermined value, the flow rate of the fluid determined by said second calculation means is outputted.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×