Acoustic transducer with damping means

• US 3,989,965 A
• Filed: 07/27/1973
• Issued: 11/02/1976
• Est. Priority Date: 07/27/1973
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Smith, Richard W., Adamson, Gerald E.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US05/383,202
• Time in Patent Office: 1,194 Days
• Field of Search: 310/8.2, 310/8.3, 310/9.1, 310/9.4, 310/9.2, 310/8.7, 310/9.7, 340/8 MM, 340/8 FT
• US Class Current: 310/334
• CPC Class Codes: B06B 1/0681 and a damping structure
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00

Abstract

An ultrasonic transducer specifically suited to high temperature sodium applications is described. A piezoelectric active element is joined to the transducer faceplate by coating the faceplate and juxtaposed active element face with wetting agents specifically compatible with the bonding procedure employed to achieve the joint. The opposite face of the active element is fitted with a backing member designed to assure continued electrical continuity during adverse operating conditions which can result in the fracturing of the active element. The fit is achieved employing a spring-loaded electrode operably arranged to electrically couple the internal transducer components, enclosed in a hermetically sealed housing, to accessory components normally employed in transducer applications.

Two alternative backing members are taught for assuring electrical continuity. The first employs a resilient, discrete multipoint contact electrode in electrical communication with the active element face. The second employs a resilient, elastomeric, electrically conductive, damped member in electrical communication with the active element face in a manner to effect ring-down of the transducer. Each embodiment provides continued electrical continuity within the transducer in the event the active element fractures, while the second provides the added benefit of damping.

Claims

1. An acoustic transducer having improved damping characteristics comprising:

an enclosed housing having a portion of one wall constructed of acoustically conductive material effectively forming an acoustic window;

a piezoelectric element having a first and second surface of corresponding opposite polarities positioned within said housing, the first of said surfaces, being in acoustic communication with the acoustic window;

a resilient, elastomeric, electrically conductive, acoustically damped backing member in electrical communication with said second surface of said piezoelectric element making electrical contact substantially over the entire continuous surface area thereof in a manner to promote electrical communication with the surface area of said second surface in the event of cracking and effect ring-down of the transducer, said backing member being formed from room temperature vulcanizing silicon rubber impregnated with tungsten, wherein the tungsten to room temperature vulcanizing rubber ratio is at least six to one by weight; and

means for electrically coupling said backing member to the exterior of said housing.