Low frequency, high sensitivity electromechanical transducer

• US 3,978,715 A
• Filed: 07/15/1974
• Issued: 09/07/1976
• Est. Priority Date: 07/15/1974
• Status: Expired due to Term

• Current Assignee: IRD Mechanalysis, Inc.
• Original Assignee: IRD Mechanalysis, Inc.
• Inventors: Farstad, Johan T.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US05/488,694
• Time in Patent Office: 785 Days
• Field of Search: 73/71.2, 73/71.4, 73/516 R, 73/517 R, 73/517 B
• US Class Current: 73/654
• CPC Class Codes: G01P 15/11 by inductive pick-up

Abstract

An electromechanical transducer employs an Eddy current type displacement sensing device mounted in confronting relation to a seismically supported, nonmagnetic metal beam which is presented within an enclosed chamber. Movement of the nonmagnetic metal beam is damped. Movement of the nonmagnetic metal beam relative to the Eddy current type displacement sensing device occurs when the device is moving cyclically at low frequencies up to about 200 Hertz. Because of the damping of the movement of the metal beam, its instantaneous displacement is proportional to the instantaneous acceleration applied to the transducer. The output electrical signal from the Eddy current displacement sensing device can be integrated to provide an output signal directly proportional to the instantaneous velocity of the transducer. The signal can be twice integrated to provide an output signal corresponding to the instantaneous displacement of the transducer.

Claims

1. A self-contained acceleration measuring device confined within an enclosed housing;

a barrier wall dividing the said housing into a first chamber and a second chamber;

a nonmagnetic metal beam pivotally mounted at one end on a torsion pivot in the said first chamber and having an unsupported free end;

said first chamber being filled with fluid as a damping means for resisting movement of the said beam;

an Eddy current type displacement sensing device mounted in said barrier wall with its sensing tip in the said first chamber and having electrical conductors extending into said second chamber;

the said free end of the said beam being disposed in confronting relation with the said Eddy current displacement sensing tip in such manner that the instantaneous displacement between the said beam and the said sensing tip corresponds to the instantaneous acceleration applied to the said housing;

means within said second chamber for generating an electrical signal directly responsive to the said instantaneous displacement between the said beam and the said sensing tip; and

means for converting the said electrical signal directly to an indication of the instantaneous acceleration of the said housing.