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Ultrasonic bubble detector

  • US 3,974,681 A
  • Filed: 10/23/1973
  • Issued: 08/17/1976
  • Est. Priority Date: 10/23/1973
  • Status: Expired due to Term
First Claim
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1. An ultrasonic through-transmission bubble detector for use with a hollow, flexible tube for feeding liquid and comprising:

  • a first sound coupling element arranged on one side of the tube and having one end defining a concave lensing surface contacting the tube;

    transducer means coupled to the other end of said first sound element;

    means applying a signal to said transducer means for causing said transducer means to establish a collimated ultrasonic signal in the first sound element;

    a second sound coupling element arranged on the opposite side of the tube to the first sound element to unidirectionally receive the ultrasonic signal transmitted through the tube and the liquid disposed in the internal space defined by the tube;

    said second sound coupling element having one end defining a concave lensing surface contacting the tube;

    said first and second element lensing surfaces extending about a major circumference of the tube but defining a gap between the facing element ends;

    the total gap circumference being less than the lensing surface circumference;

    said first and second sound coupling elements both being constructed of a material having a greater acoustic velocity than that of the liquid or tube to provide a first refractive index between the first sound coupling element and tube greater than unity at the lensing surface of the first element, and a second reciprocal refractive index between the tube and second sound coupling element at the lensing surface of the second element;

    said lensing surfaces and said material in combination providing a lensing effect, respectively, whereby the beam pattern of the ultrasonic signal is converged inside the tube and collimating the ultrasonic signal with the minimum width of the beam pattern inside the tube being less than the inner diameter of the tube;

    and means coupled from the second sound element for receiving the collimated ultrasonic signal including means for establishing an alarm condition.

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