Transducer with a flexible sensor element for measurement of mechanical values

• US 4,413,202 A
• Filed: 04/11/1983
• Issued: 11/01/1983
• Est. Priority Date: 07/27/1977
• Status: Expired due to Fees

• Current Assignee: Hans List
• Original Assignee: Hans List
• Inventors: Claassen, Peter, Krempl, Peter, List, Helmut
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US06/482,279
• Time in Patent Office: 204 Days
• Field of Search: 310/330-332, 310/338, 310/339, 310/345, 310/800, 179/110 A, 73/774-778, 73/780, 73/781, 73/700, 73/702, 73/715-718, 73/723, 73/724, 73/729, 73/753, 73/754
• US Class Current: 310/338
• CPC Class Codes: F02M 65/003 Measuring variation of fuel pressure in high pressure line
• CPC Class Codes: G01L 9/0001 Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means G01L9/0026, G01L9/0033, G01L9/0082, G01L9/0089, G01L9/0091 take precedence
• CPC Class Codes: G01L 9/0005 using variations in capacitance G01L9/0072 takes precedence
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

A transducer with a flexible sensor element for measurement of mechanical values, at least one flexible piezoelectric sensor element being provided for piezoelectrical or capacitive measurement, the opposite surfaces of the sensor element being at least partially connected to electrically leading contact surfaces.

Claims

1. An apparatus for determining the pressure of a fluid, said apparatus comprising

means forming a hollow enclosure in which the fluid whose pressure is to be measured is contained, said means including a wall member which has an edge surface that is configured to provide a cylindrical orifice that communicates with the interior of said hollow enclosure, said edge surface of said wall member including a continuous step portion which extends into said cylindrical orifice and a threaded portion, said step portion being positioned closer to the interior of said hollow enclosure than said threaded portion,

a domed membrane which has a diameter that is greater than the diameter defined by the step portion of said wall member, said domed membrane being positioned in said cylindrical orifice such that the periphery thereof is positioned between said step portion and said threaded portion of said wall member and is oriented such that the center thereof is positioned further from the interior of said hollow enclosure than said periphery,

a transducer means which has opposite ends and is positioned against the domed membrane on the side thereof facing away from the interior of said hollow enclosure, said transducer means comprising at least one flexible piezoelectric film, at least one flexible piezoelectric film in said transducer means having opposite sides and an electrically conducting surface associated with at least a portion of at least one of the opposite sides thereof,

attachment means for stretching said transducer means across said domed membrane and thus across said orifice, said attachment means comprising an annular screw which has a threaded outer surface, said threaded outer surface of said annular screw being engaged with the threaded portion of said wall means such that the annular screw will cause the opposite ends of said transducer means to be clamped and the transducer means to be stretched over said domed membrane.

2. The apparatus as defined in claim 1, wherein a contact ring is positioned between said annular screw and the opposite ends of said transducer means.

3. The apparatus as defined in claim 2, wherein an electrically-conducting washer is positioned between the domed member across which the transducer means is stretched and the step portion of the wall member forming said orifice.

4. An apparatus for determining the pressure of a fluid, said apparatus comprising

means forming a hollow enclosure in which the fluid whose pressure is to be measured is contained, said means including a wall member which has an edge surface that is configured to provide an orifice that communicates with the interior of said hollow enclosure, said edge surface of said wall member including a continuous step portion which extends into said orifice and a threaded portion,

a domed membrane which has a diameter that is greater than the diameter defined by the step portion of said wall member, said domed membrane being positioned in said orifice such that the periphery thereof is positioned between said step portion and said threaded portion of said wall member,

a transducer means which has opposite ends and is positioned against the domed membrane, said transducer means comprising at least one flexible piezoelectric film, at least one flexible piezoelectric film in said transducer means having opposite sides and an electrically conducting surface associated with at least a portion of each of the opposite sides thereof,

attachment means for stretching said transducer means across said domed membrane and thus across said orifice, said attachment means comprising an annular screw which has a threaded outer surface, said threaded outer surface of said annular screw being engaged with the threaded portion of said wall means such that the annular screw will cause the opposite ends of said transducer means to be clamped and the transducer means to be stretched over said domed membrane.

5. The apparatus as defined in claim 4, wherein each flexible piezoelectric film consists of a monoaxial-oriented polymer.

6. The apparatus as defined in claim 4, wherein each flexible piezoelectric film consists of polyvinylidene-fluoride.

7. The apparatus as defined in claim 4, wherein a contact ring is positioned between said annular screw and said transducer means.

8. The apparatus as defined in claim 7, wherein an electrically-conducting washer is positioned between the domed member across which the transducer means is stretched and the step portion of the wall member forming said orifice.

9. The apparatus as defined in claim 4 wherein said orifice is circular.

10. The apparatus as defined in claim 4 wherein said step portion is positioned closer to the interior of said hollow enclosure that said threaded portion and wherein said domed membrane is positioned such that its center is located further from the interior of said hollow enclosure than said periphery.