Low reflected energy transmission structure transducer head

• US 3,876,890 A
• Filed: 04/24/1974
• Issued: 04/08/1975
• Est. Priority Date: 04/24/1974
• Status: Expired due to Term

• Current Assignee: Alvin E. Brown, William E Van Over
• Original Assignee: Alvin E. Brown, William E Van Over
• Inventors: Brown, Alvin E., Van Over, William E.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US05/463,529
• Time in Patent Office: 349 Days
• Field of Search: 310/8.2,8.3,8.7,9.1,9.4 340/8,10 259/1R,DIG.17,DIG.44 73/194A,67.5R,67.6,67.7,DIG.4 181/.5,142
• US Class Current: 310/334
• CPC Class Codes: B06B 1/0666 used as a diaphragm
• CPC Class Codes: G10K 11/004 Mounting transducers, e.g. provided with mechanical moving or orienting device mountings specially adapted to a particular sound-producing device, see the preceding groups G10K1/00 - G10K9/00, e.g. G10K1/26, G10K1/28, G10K9/22; arrangements of sonic watch equipment on submarines B63G8/39; buoys B63B22/00

Abstract

Reflected ultrasonic wave energy within a transducer head produced by a crystal transducer mounted therein is trapped within the head by the geometric configuration of the head until the reflected wave is substantially dissipated. The geometric configuration includes a diaphragm upon which the transducer is mounted and a frusto-conical surface extending outwardly from one face of the diaphragm and intersected by a surface of revolution for forming a solid of revolution therebetween. The angle of conicity is selected to align the frusto-conical surface with the principle acoustic dispersion or shear angle in the transducer head material. The head may be mounted in a flow conduit with the frusto-conical surface in communication with the fluid and the transducer mounted on the opposite side of the diaphragm, or it may be mounted with the frusto-conical surface exterior to the conduit, and the transducer mounted on the diaphragm surface adjacent thereto. The surface of revolution may take any one of the number of forms as long as it has a geometric shape, such as to reflect within the head substantially all energy waves which emanate outwardly from the edge of the mounted transducer.

Claims

1. In a head for mounting a transducer for energy exchange with a fluid, a diaphragm for mounting the transducer having first and second faces, frusto-conical diverging walls extending from said first face away from said second face at an angle supplementary to the acoustic dispersion angle of the head material, an outer surface intersecting said frusto-conical walls and forming a solid of revolution therewith extending to the plane of said second face, said solid of revolution reflecting substantially all energy waves which emanate outwardly from the edge of the transducer at angles with the mounting surface more acute than the principle shear angle in a direction which is on the side of a normal to the point of wave incidence which is towards said first face, whereby reflected wave energy is retained within the head until substantially dissipated.

2. In a head as in claim 1 wherein the transducer is a piezo-electric crystal having a diameter substantially equivalent to the diameter described by the intersection of an imaginary extension of said frusto-conical diverging walls and said second face, and wherein said second face has a diameter equivalent to the sum of the diameter of the transducer and four times the thickness of said diaphragm.

3. In a head as in claim 2 wherein the transducer is centrally mounted on said second face, together with cylindrical side walls depending from said outer surface having an inner diameter defined by the diameter of said second face, whereby when the head is sealed in the wall of a fluid conduit with said first face in communication with the fluid, the transducer may receive energy from and impart energy to the fluid.

4. In a head as in claim 2 wherein the head material is steel and the acoustic dispersion angle is approximately 45.degree..

5. In a head as in claim 2 wherein the transducer is mounted on said first face and the head is sealably mounted in a wall of a fluid conduit with said second face in communication with the fluid, together with a cover mounted on the exterior of the fluid conduit for providing protection for the head and the transducer.

6. In a head as in claim 1 wherein said outer surface is a frustum of a cone.

7. In a head as in claim 1 wherein said outer surface describes an upper and a lower frustum of a cone, and wherein the base of said upper frustum has the same diameter as the upper surface of said lower frustum.

8. In a head as in claim 1 wherein said outer surface is a paraboloid of revolution.

9. In a head as in claim 1 wherein said outer surface has a constant radius of curvature in cross section, said radius extending normal to the locus of points describing an intersection of an extension of said frusto-conical diverging walls and said second face.

10. A head fabricated of a material having a principal shear angle substantially coinciding with an acoustic dispersion angle for mounting a transducer for transmitting ultrasonic energy through a fluid medium and for receiving ultrasonic energy transmitted through a fluid medium comprising a solid of revolution bounded by a first planar diaphragm surface, a second planar diaphragm surface parallel to said first surface, an internal frusto-conical surface intersecting said first diaphragm surface and diverging therefrom extending away from said second diaphragm surface, and an external surface intersecting said frusto-conical surface and extending to the plane of said second diaphragm surface, whereby when said transducer is mounted on said diaphragm the geometry of said solid of revolution reflects substantially all energy waves emanating outwardly from the edge of the transducer in such a direction as to retain them within said solid of revolution until substantially dissipated.

11. A head for mounting a transducer as in claim 10 wherein the transducer has a predetermined diameter and a predetermined thickness between said first and second planar diaphragm surfaces, and wherein said internal frusto-conical surface forms an angle with the axis of the cone which provides substantial alignment with the principle shear angle in the head material, and wherein an extension of said internal frusto-conical surface which intersects said second planar diaphragm surface describes a circle thereon equivalent to the diameter of the transducer, thereby defining the diameter of said first planar diaphragm surface.

12. A head for mounting a transducer as in claim 11 wherein said external surface has a constant radius of curvature in cross section, said radius extending from the mounted edge of the transducer.

13. A head for mounting a transducer as in claim 12 wherein said head material is steel having a principal shear angle which is approximately 45.degree., and wherein the diameter of said second planar diaphragm surface is equivalent to the sum of the diameter of the transducer and four times said predetermined diaphragm thickness.

14. A head for mounting a transducer as in claim 10 together with depending cylindrical walls having an outside surface meeting said external surface and having a thickness sufficient to withstand pressures in the fluid when the head is sealably inserted in the wall of a fluid conduit with said first planar diaphragm surface in communication with the fluid and the transducer mounted centrally on said second planar diaphragm surface.

15. A head for mounting a transducer as in claim 10 wherein the head is sealably mounted in the wall of a conduit containing the fluid having said second planar diaphragm surface in communication with the fluid and wherein the transducer is centrally mounted on said first planar diaphragm surface, together with a housing surrounding the head for protecting the transducer.

16. A head for mounting a transducer as in claim 10 wherein said solid of revolution intercepts substantially all ultrasonic energy waves approaching along an incoming path at said internal frusto-conical and said external surfaces, so that they are reflected outwardly in reverse direction on the incoming path and are prevented from impinging on said first and second planar diaphragm surfaces.