Transducer with a flexible piezoelectric layer as a sensor element

• US 4,737,676 A
• Filed: 12/17/1986
• Issued: 04/12/1988
• Est. Priority Date: 12/20/1985
• Status: Expired due to Term

• Current Assignee: A V L Gesellschaft Fur Verbrennungskraftmaschinen und Messtechnik mbH
• Original Assignee: AVL Gesellschaft Fur Verbrennungskraftmaschinen und Messtechnik mbH PROF Drdrhc HANS List, Hans List
• Inventors: Engel, Gunter, Harms, Klaus-Christoph, Krempl, Peter W., List, Helmut
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US06/942,783
• Time in Patent Office: 482 Days
• Field of Search: 310/322, 310/324, 310/334, 310/360, 310/346, 310/800, 310/338, 310/330-332, 73/702, 73/704, 73/715, 73/716, 73/717, 73/753, 73/754, 73/730, 73/756, 73/119 A, 73/DIG. 4
• US Class Current: 310/330
• CPC Class Codes: H10N 30/302 Sensors

Abstract

A transducer comprising a flexible piezoelectric layer as a sensor element for measuring mechanical quantities in hollow bodies, above all pressures in pipes, the opposite sides of this layer being bonded to electrically-conductive contact layers and being connectable via leads to a display and evaluation unit. In order to achieve a high temperature stability in such transducers and to make them suitable for use at temperatures exceeding 80° C., the piezoelectric layer is proposed to consist of wurtzite or sphalerite. One of the electrically-conductive contact layers can be of some heat-resistant, flexible supporting material, for instance flexible metal foil, such as Cu-Be foil, or a sheet of plastic, one or both of whose sides are metallized, and the other electrically-conductive contact layer can be a metal coating applied by evaporation.

Claims

1. A flexible transducer which can be attached to a hollow body to measure a mechanical condition thereof, said transducer comprising an elongated heat-resistant, flexible metal foil having a first surface and a second surface;

an elongated flexible piezoelectric substrate having a first surface and a second surface, the first surface of said flexible piezoelectric substrate contacting and covering the entire second surface of said heat- resistant, flexible metal foil, said flexible piezoelectric substrate being heat resistant up to at least 80°

C. and made of a material selected from the group consisting of wurtzite and sphalerite; and

an elongated coating of an electrically-conductive material on the second surface of said flexible, piezoelectric substrate;

said heat-resistant, flexible metal foil and said coating of an electrically-conducting material being connectable to electrical leads.

2. A flexible transducer according to claim 1, wherein said heat-resistant, flexible metal foil is composed of Cu-Be.

3. A flexible transducer according to claim 1, wherein said coating of electrically-conducting material is made of metal.

4. A flexible transducer which can be attached to a hollow body to measure a mechanical condition thereof, said transducer comprising an elongated heat-resistant, flexible sheet of plastic having opposite sides, at least one of said opposite sides being metallized;

an elongated flexible piezoelectric substrate having a first surface and a second surface, the first surface of said flexible piezoelectric substrate contacting and covering the entirety of one of the metallized surfaces of said heat-resistant, flexible sheet of plastic, said flexible piezoelectric substrate being heat resistant up to at least 80°

C. and made of a material selected from the group consisting of wurtzite and sphalerite; and

an elongated coating of an electrically-conductive material on the second surface of said flexible, piezoelectric substrate.

5. A flexible transducer according to claim 4, wherein said coating of electrically-conducting material is made of metal.

6. The combination of a pipe and a flexible transducer partially wrapped therearound to measure a mechanical condition of said pipe, said flexible transducer comprising an elongated heat-resistant, flexible metal foil having a first surface and a second surface;

an elongated flexible piezoelectric substrate having a first surface and a second surface, the first surface of said flexible piezoelectric substrate contacting and covering the entire second surface of said heat-resistant, flexible metal foil, said flexible piezoelectric substrate being heat resistant up to at least 80°

C. and made of a material selected from the group consisting of wurtzite and sphalerite; and

an elongated coating of an electrically-conductive material on the second surface of said flexible, piezoelectric substrate;

said heat-resistant, flexible metal foil and said coating of an electrically-conductive material being connectable to electrical leads.

7. The combination of a pipe and a flexible transducer partially wrapped therearound to measure a mechanical condition of said pipe, said flexible transducer comprising an elongated heat-resistant, flexible sheet of plastic having opposite sides, at least one of said opposite sides being metallized;

an elongated flexible piezoelectric substrate having a first surface and a second surface, the first surface of said flexible piezoelectric substrate contacting and covering the entirety of one of the metallized surfaces of said heat-resistant, flexible sheet of plastic, said flexible piezoelectric substrate being heat resistant up to at least 80°

C. and made of a material selected from the group consisting of wurtzite and sphalerite; and

an elongated coating of an electrically-conductive material on the second surface of said flexible, piezoelectric substrate.