Replaceable element ultrasonic flowmeter transducer

Abstract

An electroacoustic ultrasonic transducer is described which is usable under high pressure and high temperature operating conditions, and is readily replaceable. A piezoelectric transducer element is disposed within a metallic housing and coupled to a metallic acoustic window which is exposed to the sensed acoustic medium, with very efficient acoustic coupling between the piezoelectric element, the acoustic window, and a damping block disposed behind the piezoelectric element.

We claim: 
     
       1. An acoustic transducer assembly comprising: an electrically conductive, generally tubular metal transducer housing;   an acoustically transmissive metal window sealingly disposed at one end of the transducer housing, with the .[.exterior and.]. interior .[.surfaces.]. .Iadd.surface .Iaddend.of the metal window being lapped optically flat for optimum acoustic coupling;   a thin disk, piezoelectric transducer element having opposed surfaces lapped optically flat and one such surface in optical contact with the interior surface of the metal window;   an insulating sleeve disposed within the generally tubular metal transducer housing;   a generally cylindrical acoustic wave damping block disposed within the insulating sleeve, which damping block is electrically conductive and has one end surface lapped optically flat and in optical contact with the transducer element disk, while the other end of the damping block has a convex cone shaped terminus;   an electrical contact member disposed within the insulating sleeve and having a concave conically shaped surface which mates with the damping block convex cone shaped terminus, which contact member is retained in physical and electrical contact with the damping block by a coil spring means disposed within the insulating sleeve;   an insulating plate provided at one end of the insulating sleeve contacting the coil spring and having an electrical lead-in extending therethrough connected to the contact member, whereby electrical connection is made to the interior surface of the transducer element serially via the electrical contact member and the conductive damping block, with the metal transducer housing serving as another electrical lead to the other side of the transducer element via the metal window;   a closure member closing the tubular transducer housing and connectable thereto about the insulating plate and contacting the insulating plate to thereby compress the coil spring to compress together the contact member, the damping block, and the transducer element to the metal window.   
     
     
       2. The acoustic transducer assembly specified in claim 1, wherein the generally cylindrical damping block comprises an enlarged diameter end portion which terminates with a convex cone shaped end so that the length of travel of internally reflected acoustic waves is extended.